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-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/address_is_readable.cc139
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/address_is_readable.h32
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/demangle.cc1945
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/demangle.h71
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/demangle_test.cc197
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/elf_mem_image.cc382
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/elf_mem_image.h134
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/examine_stack.cc187
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/examine_stack.h42
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/stack_consumption.cc185
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/stack_consumption.h50
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/stack_consumption_test.cc50
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc199
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/stacktrace_arm-inl.inc134
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/stacktrace_config.h89
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/stacktrace_generic-inl.inc108
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/stacktrace_powerpc-inl.inc248
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/stacktrace_unimplemented-inl.inc24
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/stacktrace_win32-inl.inc93
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/stacktrace_x86-inl.inc346
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/symbolize.h147
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/vdso_support.cc173
-rw-r--r--third_party/abseil_cpp/absl/debugging/internal/vdso_support.h158
23 files changed, 0 insertions, 5133 deletions
diff --git a/third_party/abseil_cpp/absl/debugging/internal/address_is_readable.cc b/third_party/abseil_cpp/absl/debugging/internal/address_is_readable.cc
deleted file mode 100644
index 329c285f3b58..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/address_is_readable.cc
+++ /dev/null
@@ -1,139 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// base::AddressIsReadable() probes an address to see whether it is readable,
-// without faulting.
-
-#include "absl/debugging/internal/address_is_readable.h"
-
-#if !defined(__linux__) || defined(__ANDROID__)
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-// On platforms other than Linux, just return true.
-bool AddressIsReadable(const void* /* addr */) { return true; }
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#else
-
-#include <fcntl.h>
-#include <sys/syscall.h>
-#include <unistd.h>
-
-#include <atomic>
-#include <cerrno>
-#include <cstdint>
-
-#include "absl/base/internal/errno_saver.h"
-#include "absl/base/internal/raw_logging.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-// Pack a pid and two file descriptors into a 64-bit word,
-// using 16, 24, and 24 bits for each respectively.
-static uint64_t Pack(uint64_t pid, uint64_t read_fd, uint64_t write_fd) {
-  ABSL_RAW_CHECK((read_fd >> 24) == 0 && (write_fd >> 24) == 0,
-                 "fd out of range");
-  return (pid << 48) | ((read_fd & 0xffffff) << 24) | (write_fd & 0xffffff);
-}
-
-// Unpack x into a pid and two file descriptors, where x was created with
-// Pack().
-static void Unpack(uint64_t x, int *pid, int *read_fd, int *write_fd) {
-  *pid = x >> 48;
-  *read_fd = (x >> 24) & 0xffffff;
-  *write_fd = x & 0xffffff;
-}
-
-// Return whether the byte at *addr is readable, without faulting.
-// Save and restores errno.   Returns true on systems where
-// unimplemented.
-// This is a namespace-scoped variable for correct zero-initialization.
-static std::atomic<uint64_t> pid_and_fds;  // initially 0, an invalid pid.
-
-bool AddressIsReadable(const void *addr) {
-  absl::base_internal::ErrnoSaver errno_saver;
-  // We test whether a byte is readable by using write().  Normally, this would
-  // be done via a cached file descriptor to /dev/null, but linux fails to
-  // check whether the byte is readable when the destination is /dev/null, so
-  // we use a cached pipe.  We store the pid of the process that created the
-  // pipe to handle the case where a process forks, and the child closes all
-  // the file descriptors and then calls this routine.  This is not perfect:
-  // the child could use the routine, then close all file descriptors and then
-  // use this routine again.  But the likely use of this routine is when
-  // crashing, to test the validity of pages when dumping the stack.  Beware
-  // that we may leak file descriptors, but we're unlikely to leak many.
-  int bytes_written;
-  int current_pid = getpid() & 0xffff;   // we use only the low order 16 bits
-  do {  // until we do not get EBADF trying to use file descriptors
-    int pid;
-    int read_fd;
-    int write_fd;
-    uint64_t local_pid_and_fds = pid_and_fds.load(std::memory_order_acquire);
-    Unpack(local_pid_and_fds, &pid, &read_fd, &write_fd);
-    while (current_pid != pid) {
-      int p[2];
-      // new pipe
-      if (pipe(p) != 0) {
-        ABSL_RAW_LOG(FATAL, "Failed to create pipe, errno=%d", errno);
-      }
-      fcntl(p[0], F_SETFD, FD_CLOEXEC);
-      fcntl(p[1], F_SETFD, FD_CLOEXEC);
-      uint64_t new_pid_and_fds = Pack(current_pid, p[0], p[1]);
-      if (pid_and_fds.compare_exchange_strong(
-              local_pid_and_fds, new_pid_and_fds, std::memory_order_release,
-              std::memory_order_relaxed)) {
-        local_pid_and_fds = new_pid_and_fds;  // fds exposed to other threads
-      } else {  // fds not exposed to other threads; we can close them.
-        close(p[0]);
-        close(p[1]);
-        local_pid_and_fds = pid_and_fds.load(std::memory_order_acquire);
-      }
-      Unpack(local_pid_and_fds, &pid, &read_fd, &write_fd);
-    }
-    errno = 0;
-    // Use syscall(SYS_write, ...) instead of write() to prevent ASAN
-    // and other checkers from complaining about accesses to arbitrary
-    // memory.
-    do {
-      bytes_written = syscall(SYS_write, write_fd, addr, 1);
-    } while (bytes_written == -1 && errno == EINTR);
-    if (bytes_written == 1) {   // remove the byte from the pipe
-      char c;
-      while (read(read_fd, &c, 1) == -1 && errno == EINTR) {
-      }
-    }
-    if (errno == EBADF) {  // Descriptors invalid.
-      // If pid_and_fds contains the problematic file descriptors we just used,
-      // this call will forget them, and the loop will try again.
-      pid_and_fds.compare_exchange_strong(local_pid_and_fds, 0,
-                                          std::memory_order_release,
-                                          std::memory_order_relaxed);
-    }
-  } while (errno == EBADF);
-  return bytes_written == 1;
-}
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif
diff --git a/third_party/abseil_cpp/absl/debugging/internal/address_is_readable.h b/third_party/abseil_cpp/absl/debugging/internal/address_is_readable.h
deleted file mode 100644
index 4bbaf4d69bd8..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/address_is_readable.h
+++ /dev/null
@@ -1,32 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#ifndef ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_
-#define ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_
-
-#include "absl/base/config.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-// Return whether the byte at *addr is readable, without faulting.
-// Save and restores errno.
-bool AddressIsReadable(const void *addr);
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/demangle.cc b/third_party/abseil_cpp/absl/debugging/internal/demangle.cc
deleted file mode 100644
index 46cdb67b1fbf..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/demangle.cc
+++ /dev/null
@@ -1,1945 +0,0 @@
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// For reference check out:
-// https://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangling
-//
-// Note that we only have partial C++11 support yet.
-
-#include "absl/debugging/internal/demangle.h"
-
-#include <cstdint>
-#include <cstdio>
-#include <limits>
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-typedef struct {
-  const char *abbrev;
-  const char *real_name;
-  // Number of arguments in <expression> context, or 0 if disallowed.
-  int arity;
-} AbbrevPair;
-
-// List of operators from Itanium C++ ABI.
-static const AbbrevPair kOperatorList[] = {
-    // New has special syntax (not currently supported).
-    {"nw", "new", 0},
-    {"na", "new[]", 0},
-
-    // Works except that the 'gs' prefix is not supported.
-    {"dl", "delete", 1},
-    {"da", "delete[]", 1},
-
-    {"ps", "+", 1},  // "positive"
-    {"ng", "-", 1},  // "negative"
-    {"ad", "&", 1},  // "address-of"
-    {"de", "*", 1},  // "dereference"
-    {"co", "~", 1},
-
-    {"pl", "+", 2},
-    {"mi", "-", 2},
-    {"ml", "*", 2},
-    {"dv", "/", 2},
-    {"rm", "%", 2},
-    {"an", "&", 2},
-    {"or", "|", 2},
-    {"eo", "^", 2},
-    {"aS", "=", 2},
-    {"pL", "+=", 2},
-    {"mI", "-=", 2},
-    {"mL", "*=", 2},
-    {"dV", "/=", 2},
-    {"rM", "%=", 2},
-    {"aN", "&=", 2},
-    {"oR", "|=", 2},
-    {"eO", "^=", 2},
-    {"ls", "<<", 2},
-    {"rs", ">>", 2},
-    {"lS", "<<=", 2},
-    {"rS", ">>=", 2},
-    {"eq", "==", 2},
-    {"ne", "!=", 2},
-    {"lt", "<", 2},
-    {"gt", ">", 2},
-    {"le", "<=", 2},
-    {"ge", ">=", 2},
-    {"nt", "!", 1},
-    {"aa", "&&", 2},
-    {"oo", "||", 2},
-    {"pp", "++", 1},
-    {"mm", "--", 1},
-    {"cm", ",", 2},
-    {"pm", "->*", 2},
-    {"pt", "->", 0},  // Special syntax
-    {"cl", "()", 0},  // Special syntax
-    {"ix", "[]", 2},
-    {"qu", "?", 3},
-    {"st", "sizeof", 0},  // Special syntax
-    {"sz", "sizeof", 1},  // Not a real operator name, but used in expressions.
-    {nullptr, nullptr, 0},
-};
-
-// List of builtin types from Itanium C++ ABI.
-//
-// Invariant: only one- or two-character type abbreviations here.
-static const AbbrevPair kBuiltinTypeList[] = {
-    {"v", "void", 0},
-    {"w", "wchar_t", 0},
-    {"b", "bool", 0},
-    {"c", "char", 0},
-    {"a", "signed char", 0},
-    {"h", "unsigned char", 0},
-    {"s", "short", 0},
-    {"t", "unsigned short", 0},
-    {"i", "int", 0},
-    {"j", "unsigned int", 0},
-    {"l", "long", 0},
-    {"m", "unsigned long", 0},
-    {"x", "long long", 0},
-    {"y", "unsigned long long", 0},
-    {"n", "__int128", 0},
-    {"o", "unsigned __int128", 0},
-    {"f", "float", 0},
-    {"d", "double", 0},
-    {"e", "long double", 0},
-    {"g", "__float128", 0},
-    {"z", "ellipsis", 0},
-
-    {"De", "decimal128", 0},      // IEEE 754r decimal floating point (128 bits)
-    {"Dd", "decimal64", 0},       // IEEE 754r decimal floating point (64 bits)
-    {"Dc", "decltype(auto)", 0},
-    {"Da", "auto", 0},
-    {"Dn", "std::nullptr_t", 0},  // i.e., decltype(nullptr)
-    {"Df", "decimal32", 0},       // IEEE 754r decimal floating point (32 bits)
-    {"Di", "char32_t", 0},
-    {"Du", "char8_t", 0},
-    {"Ds", "char16_t", 0},
-    {"Dh", "float16", 0},         // IEEE 754r half-precision float (16 bits)
-    {nullptr, nullptr, 0},
-};
-
-// List of substitutions Itanium C++ ABI.
-static const AbbrevPair kSubstitutionList[] = {
-    {"St", "", 0},
-    {"Sa", "allocator", 0},
-    {"Sb", "basic_string", 0},
-    // std::basic_string<char, std::char_traits<char>,std::allocator<char> >
-    {"Ss", "string", 0},
-    // std::basic_istream<char, std::char_traits<char> >
-    {"Si", "istream", 0},
-    // std::basic_ostream<char, std::char_traits<char> >
-    {"So", "ostream", 0},
-    // std::basic_iostream<char, std::char_traits<char> >
-    {"Sd", "iostream", 0},
-    {nullptr, nullptr, 0},
-};
-
-// State needed for demangling.  This struct is copied in almost every stack
-// frame, so every byte counts.
-typedef struct {
-  int mangled_idx;                   // Cursor of mangled name.
-  int out_cur_idx;                   // Cursor of output string.
-  int prev_name_idx;                 // For constructors/destructors.
-  signed int prev_name_length : 16;  // For constructors/destructors.
-  signed int nest_level : 15;        // For nested names.
-  unsigned int append : 1;           // Append flag.
-  // Note: for some reason MSVC can't pack "bool append : 1" into the same int
-  // with the above two fields, so we use an int instead.  Amusingly it can pack
-  // "signed bool" as expected, but relying on that to continue to be a legal
-  // type seems ill-advised (as it's illegal in at least clang).
-} ParseState;
-
-static_assert(sizeof(ParseState) == 4 * sizeof(int),
-              "unexpected size of ParseState");
-
-// One-off state for demangling that's not subject to backtracking -- either
-// constant data, data that's intentionally immune to backtracking (steps), or
-// data that would never be changed by backtracking anyway (recursion_depth).
-//
-// Only one copy of this exists for each call to Demangle, so the size of this
-// struct is nearly inconsequential.
-typedef struct {
-  const char *mangled_begin;  // Beginning of input string.
-  char *out;                  // Beginning of output string.
-  int out_end_idx;            // One past last allowed output character.
-  int recursion_depth;        // For stack exhaustion prevention.
-  int steps;               // Cap how much work we'll do, regardless of depth.
-  ParseState parse_state;  // Backtrackable state copied for most frames.
-} State;
-
-namespace {
-// Prevent deep recursion / stack exhaustion.
-// Also prevent unbounded handling of complex inputs.
-class ComplexityGuard {
- public:
-  explicit ComplexityGuard(State *state) : state_(state) {
-    ++state->recursion_depth;
-    ++state->steps;
-  }
-  ~ComplexityGuard() { --state_->recursion_depth; }
-
-  // 256 levels of recursion seems like a reasonable upper limit on depth.
-  // 128 is not enough to demagle synthetic tests from demangle_unittest.txt:
-  // "_ZaaZZZZ..." and "_ZaaZcvZcvZ..."
-  static constexpr int kRecursionDepthLimit = 256;
-
-  // We're trying to pick a charitable upper-limit on how many parse steps are
-  // necessary to handle something that a human could actually make use of.
-  // This is mostly in place as a bound on how much work we'll do if we are
-  // asked to demangle an mangled name from an untrusted source, so it should be
-  // much larger than the largest expected symbol, but much smaller than the
-  // amount of work we can do in, e.g., a second.
-  //
-  // Some real-world symbols from an arbitrary binary started failing between
-  // 2^12 and 2^13, so we multiply the latter by an extra factor of 16 to set
-  // the limit.
-  //
-  // Spending one second on 2^17 parse steps would require each step to take
-  // 7.6us, or ~30000 clock cycles, so it's safe to say this can be done in
-  // under a second.
-  static constexpr int kParseStepsLimit = 1 << 17;
-
-  bool IsTooComplex() const {
-    return state_->recursion_depth > kRecursionDepthLimit ||
-           state_->steps > kParseStepsLimit;
-  }
-
- private:
-  State *state_;
-};
-}  // namespace
-
-// We don't use strlen() in libc since it's not guaranteed to be async
-// signal safe.
-static size_t StrLen(const char *str) {
-  size_t len = 0;
-  while (*str != '\0') {
-    ++str;
-    ++len;
-  }
-  return len;
-}
-
-// Returns true if "str" has at least "n" characters remaining.
-static bool AtLeastNumCharsRemaining(const char *str, int n) {
-  for (int i = 0; i < n; ++i) {
-    if (str[i] == '\0') {
-      return false;
-    }
-  }
-  return true;
-}
-
-// Returns true if "str" has "prefix" as a prefix.
-static bool StrPrefix(const char *str, const char *prefix) {
-  size_t i = 0;
-  while (str[i] != '\0' && prefix[i] != '\0' && str[i] == prefix[i]) {
-    ++i;
-  }
-  return prefix[i] == '\0';  // Consumed everything in "prefix".
-}
-
-static void InitState(State *state, const char *mangled, char *out,
-                      int out_size) {
-  state->mangled_begin = mangled;
-  state->out = out;
-  state->out_end_idx = out_size;
-  state->recursion_depth = 0;
-  state->steps = 0;
-
-  state->parse_state.mangled_idx = 0;
-  state->parse_state.out_cur_idx = 0;
-  state->parse_state.prev_name_idx = 0;
-  state->parse_state.prev_name_length = -1;
-  state->parse_state.nest_level = -1;
-  state->parse_state.append = true;
-}
-
-static inline const char *RemainingInput(State *state) {
-  return &state->mangled_begin[state->parse_state.mangled_idx];
-}
-
-// Returns true and advances "mangled_idx" if we find "one_char_token"
-// at "mangled_idx" position.  It is assumed that "one_char_token" does
-// not contain '\0'.
-static bool ParseOneCharToken(State *state, const char one_char_token) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (RemainingInput(state)[0] == one_char_token) {
-    ++state->parse_state.mangled_idx;
-    return true;
-  }
-  return false;
-}
-
-// Returns true and advances "mangled_cur" if we find "two_char_token"
-// at "mangled_cur" position.  It is assumed that "two_char_token" does
-// not contain '\0'.
-static bool ParseTwoCharToken(State *state, const char *two_char_token) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (RemainingInput(state)[0] == two_char_token[0] &&
-      RemainingInput(state)[1] == two_char_token[1]) {
-    state->parse_state.mangled_idx += 2;
-    return true;
-  }
-  return false;
-}
-
-// Returns true and advances "mangled_cur" if we find any character in
-// "char_class" at "mangled_cur" position.
-static bool ParseCharClass(State *state, const char *char_class) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (RemainingInput(state)[0] == '\0') {
-    return false;
-  }
-  const char *p = char_class;
-  for (; *p != '\0'; ++p) {
-    if (RemainingInput(state)[0] == *p) {
-      ++state->parse_state.mangled_idx;
-      return true;
-    }
-  }
-  return false;
-}
-
-static bool ParseDigit(State *state, int *digit) {
-  char c = RemainingInput(state)[0];
-  if (ParseCharClass(state, "0123456789")) {
-    if (digit != nullptr) {
-      *digit = c - '0';
-    }
-    return true;
-  }
-  return false;
-}
-
-// This function is used for handling an optional non-terminal.
-static bool Optional(bool /*status*/) { return true; }
-
-// This function is used for handling <non-terminal>+ syntax.
-typedef bool (*ParseFunc)(State *);
-static bool OneOrMore(ParseFunc parse_func, State *state) {
-  if (parse_func(state)) {
-    while (parse_func(state)) {
-    }
-    return true;
-  }
-  return false;
-}
-
-// This function is used for handling <non-terminal>* syntax. The function
-// always returns true and must be followed by a termination token or a
-// terminating sequence not handled by parse_func (e.g.
-// ParseOneCharToken(state, 'E')).
-static bool ZeroOrMore(ParseFunc parse_func, State *state) {
-  while (parse_func(state)) {
-  }
-  return true;
-}
-
-// Append "str" at "out_cur_idx".  If there is an overflow, out_cur_idx is
-// set to out_end_idx+1.  The output string is ensured to
-// always terminate with '\0' as long as there is no overflow.
-static void Append(State *state, const char *const str, const int length) {
-  for (int i = 0; i < length; ++i) {
-    if (state->parse_state.out_cur_idx + 1 <
-        state->out_end_idx) {  // +1 for '\0'
-      state->out[state->parse_state.out_cur_idx++] = str[i];
-    } else {
-      // signal overflow
-      state->parse_state.out_cur_idx = state->out_end_idx + 1;
-      break;
-    }
-  }
-  if (state->parse_state.out_cur_idx < state->out_end_idx) {
-    state->out[state->parse_state.out_cur_idx] =
-        '\0';  // Terminate it with '\0'
-  }
-}
-
-// We don't use equivalents in libc to avoid locale issues.
-static bool IsLower(char c) { return c >= 'a' && c <= 'z'; }
-
-static bool IsAlpha(char c) {
-  return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
-}
-
-static bool IsDigit(char c) { return c >= '0' && c <= '9'; }
-
-// Returns true if "str" is a function clone suffix.  These suffixes are used
-// by GCC 4.5.x and later versions (and our locally-modified version of GCC
-// 4.4.x) to indicate functions which have been cloned during optimization.
-// We treat any sequence (.<alpha>+.<digit>+)+ as a function clone suffix.
-static bool IsFunctionCloneSuffix(const char *str) {
-  size_t i = 0;
-  while (str[i] != '\0') {
-    // Consume a single .<alpha>+.<digit>+ sequence.
-    if (str[i] != '.' || !IsAlpha(str[i + 1])) {
-      return false;
-    }
-    i += 2;
-    while (IsAlpha(str[i])) {
-      ++i;
-    }
-    if (str[i] != '.' || !IsDigit(str[i + 1])) {
-      return false;
-    }
-    i += 2;
-    while (IsDigit(str[i])) {
-      ++i;
-    }
-  }
-  return true;  // Consumed everything in "str".
-}
-
-static bool EndsWith(State *state, const char chr) {
-  return state->parse_state.out_cur_idx > 0 &&
-         state->parse_state.out_cur_idx < state->out_end_idx &&
-         chr == state->out[state->parse_state.out_cur_idx - 1];
-}
-
-// Append "str" with some tweaks, iff "append" state is true.
-static void MaybeAppendWithLength(State *state, const char *const str,
-                                  const int length) {
-  if (state->parse_state.append && length > 0) {
-    // Append a space if the output buffer ends with '<' and "str"
-    // starts with '<' to avoid <<<.
-    if (str[0] == '<' && EndsWith(state, '<')) {
-      Append(state, " ", 1);
-    }
-    // Remember the last identifier name for ctors/dtors,
-    // but only if we haven't yet overflown the buffer.
-    if (state->parse_state.out_cur_idx < state->out_end_idx &&
-        (IsAlpha(str[0]) || str[0] == '_')) {
-      state->parse_state.prev_name_idx = state->parse_state.out_cur_idx;
-      state->parse_state.prev_name_length = length;
-    }
-    Append(state, str, length);
-  }
-}
-
-// Appends a positive decimal number to the output if appending is enabled.
-static bool MaybeAppendDecimal(State *state, unsigned int val) {
-  // Max {32-64}-bit unsigned int is 20 digits.
-  constexpr size_t kMaxLength = 20;
-  char buf[kMaxLength];
-
-  // We can't use itoa or sprintf as neither is specified to be
-  // async-signal-safe.
-  if (state->parse_state.append) {
-    // We can't have a one-before-the-beginning pointer, so instead start with
-    // one-past-the-end and manipulate one character before the pointer.
-    char *p = &buf[kMaxLength];
-    do {  // val=0 is the only input that should write a leading zero digit.
-      *--p = (val % 10) + '0';
-      val /= 10;
-    } while (p > buf && val != 0);
-
-    // 'p' landed on the last character we set.  How convenient.
-    Append(state, p, kMaxLength - (p - buf));
-  }
-
-  return true;
-}
-
-// A convenient wrapper around MaybeAppendWithLength().
-// Returns true so that it can be placed in "if" conditions.
-static bool MaybeAppend(State *state, const char *const str) {
-  if (state->parse_state.append) {
-    int length = StrLen(str);
-    MaybeAppendWithLength(state, str, length);
-  }
-  return true;
-}
-
-// This function is used for handling nested names.
-static bool EnterNestedName(State *state) {
-  state->parse_state.nest_level = 0;
-  return true;
-}
-
-// This function is used for handling nested names.
-static bool LeaveNestedName(State *state, int16_t prev_value) {
-  state->parse_state.nest_level = prev_value;
-  return true;
-}
-
-// Disable the append mode not to print function parameters, etc.
-static bool DisableAppend(State *state) {
-  state->parse_state.append = false;
-  return true;
-}
-
-// Restore the append mode to the previous state.
-static bool RestoreAppend(State *state, bool prev_value) {
-  state->parse_state.append = prev_value;
-  return true;
-}
-
-// Increase the nest level for nested names.
-static void MaybeIncreaseNestLevel(State *state) {
-  if (state->parse_state.nest_level > -1) {
-    ++state->parse_state.nest_level;
-  }
-}
-
-// Appends :: for nested names if necessary.
-static void MaybeAppendSeparator(State *state) {
-  if (state->parse_state.nest_level >= 1) {
-    MaybeAppend(state, "::");
-  }
-}
-
-// Cancel the last separator if necessary.
-static void MaybeCancelLastSeparator(State *state) {
-  if (state->parse_state.nest_level >= 1 && state->parse_state.append &&
-      state->parse_state.out_cur_idx >= 2) {
-    state->parse_state.out_cur_idx -= 2;
-    state->out[state->parse_state.out_cur_idx] = '\0';
-  }
-}
-
-// Returns true if the identifier of the given length pointed to by
-// "mangled_cur" is anonymous namespace.
-static bool IdentifierIsAnonymousNamespace(State *state, int length) {
-  // Returns true if "anon_prefix" is a proper prefix of "mangled_cur".
-  static const char anon_prefix[] = "_GLOBAL__N_";
-  return (length > static_cast<int>(sizeof(anon_prefix) - 1) &&
-          StrPrefix(RemainingInput(state), anon_prefix));
-}
-
-// Forward declarations of our parsing functions.
-static bool ParseMangledName(State *state);
-static bool ParseEncoding(State *state);
-static bool ParseName(State *state);
-static bool ParseUnscopedName(State *state);
-static bool ParseNestedName(State *state);
-static bool ParsePrefix(State *state);
-static bool ParseUnqualifiedName(State *state);
-static bool ParseSourceName(State *state);
-static bool ParseLocalSourceName(State *state);
-static bool ParseUnnamedTypeName(State *state);
-static bool ParseNumber(State *state, int *number_out);
-static bool ParseFloatNumber(State *state);
-static bool ParseSeqId(State *state);
-static bool ParseIdentifier(State *state, int length);
-static bool ParseOperatorName(State *state, int *arity);
-static bool ParseSpecialName(State *state);
-static bool ParseCallOffset(State *state);
-static bool ParseNVOffset(State *state);
-static bool ParseVOffset(State *state);
-static bool ParseCtorDtorName(State *state);
-static bool ParseDecltype(State *state);
-static bool ParseType(State *state);
-static bool ParseCVQualifiers(State *state);
-static bool ParseBuiltinType(State *state);
-static bool ParseFunctionType(State *state);
-static bool ParseBareFunctionType(State *state);
-static bool ParseClassEnumType(State *state);
-static bool ParseArrayType(State *state);
-static bool ParsePointerToMemberType(State *state);
-static bool ParseTemplateParam(State *state);
-static bool ParseTemplateTemplateParam(State *state);
-static bool ParseTemplateArgs(State *state);
-static bool ParseTemplateArg(State *state);
-static bool ParseBaseUnresolvedName(State *state);
-static bool ParseUnresolvedName(State *state);
-static bool ParseExpression(State *state);
-static bool ParseExprPrimary(State *state);
-static bool ParseExprCastValue(State *state);
-static bool ParseLocalName(State *state);
-static bool ParseLocalNameSuffix(State *state);
-static bool ParseDiscriminator(State *state);
-static bool ParseSubstitution(State *state, bool accept_std);
-
-// Implementation note: the following code is a straightforward
-// translation of the Itanium C++ ABI defined in BNF with a couple of
-// exceptions.
-//
-// - Support GNU extensions not defined in the Itanium C++ ABI
-// - <prefix> and <template-prefix> are combined to avoid infinite loop
-// - Reorder patterns to shorten the code
-// - Reorder patterns to give greedier functions precedence
-//   We'll mark "Less greedy than" for these cases in the code
-//
-// Each parsing function changes the parse state and returns true on
-// success, or returns false and doesn't change the parse state (note:
-// the parse-steps counter increases regardless of success or failure).
-// To ensure that the parse state isn't changed in the latter case, we
-// save the original state before we call multiple parsing functions
-// consecutively with &&, and restore it if unsuccessful.  See
-// ParseEncoding() as an example of this convention.  We follow the
-// convention throughout the code.
-//
-// Originally we tried to do demangling without following the full ABI
-// syntax but it turned out we needed to follow the full syntax to
-// parse complicated cases like nested template arguments.  Note that
-// implementing a full-fledged demangler isn't trivial (libiberty's
-// cp-demangle.c has +4300 lines).
-//
-// Note that (foo) in <(foo) ...> is a modifier to be ignored.
-//
-// Reference:
-// - Itanium C++ ABI
-//   <https://mentorembedded.github.io/cxx-abi/abi.html#mangling>
-
-// <mangled-name> ::= _Z <encoding>
-static bool ParseMangledName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  return ParseTwoCharToken(state, "_Z") && ParseEncoding(state);
-}
-
-// <encoding> ::= <(function) name> <bare-function-type>
-//            ::= <(data) name>
-//            ::= <special-name>
-static bool ParseEncoding(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  // Implementing the first two productions together as <name>
-  // [<bare-function-type>] avoids exponential blowup of backtracking.
-  //
-  // Since Optional(...) can't fail, there's no need to copy the state for
-  // backtracking.
-  if (ParseName(state) && Optional(ParseBareFunctionType(state))) {
-    return true;
-  }
-
-  if (ParseSpecialName(state)) {
-    return true;
-  }
-  return false;
-}
-
-// <name> ::= <nested-name>
-//        ::= <unscoped-template-name> <template-args>
-//        ::= <unscoped-name>
-//        ::= <local-name>
-static bool ParseName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseNestedName(state) || ParseLocalName(state)) {
-    return true;
-  }
-
-  // We reorganize the productions to avoid re-parsing unscoped names.
-  // - Inline <unscoped-template-name> productions:
-  //   <name> ::= <substitution> <template-args>
-  //          ::= <unscoped-name> <template-args>
-  //          ::= <unscoped-name>
-  // - Merge the two productions that start with unscoped-name:
-  //   <name> ::= <unscoped-name> [<template-args>]
-
-  ParseState copy = state->parse_state;
-  // "std<...>" isn't a valid name.
-  if (ParseSubstitution(state, /*accept_std=*/false) &&
-      ParseTemplateArgs(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Note there's no need to restore state after this since only the first
-  // subparser can fail.
-  return ParseUnscopedName(state) && Optional(ParseTemplateArgs(state));
-}
-
-// <unscoped-name> ::= <unqualified-name>
-//                 ::= St <unqualified-name>
-static bool ParseUnscopedName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseUnqualifiedName(state)) {
-    return true;
-  }
-
-  ParseState copy = state->parse_state;
-  if (ParseTwoCharToken(state, "St") && MaybeAppend(state, "std::") &&
-      ParseUnqualifiedName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <ref-qualifer> ::= R // lvalue method reference qualifier
-//                ::= O // rvalue method reference qualifier
-static inline bool ParseRefQualifier(State *state) {
-  return ParseCharClass(state, "OR");
-}
-
-// <nested-name> ::= N [<CV-qualifiers>] [<ref-qualifier>] <prefix>
-//                   <unqualified-name> E
-//               ::= N [<CV-qualifiers>] [<ref-qualifier>] <template-prefix>
-//                   <template-args> E
-static bool ParseNestedName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'N') && EnterNestedName(state) &&
-      Optional(ParseCVQualifiers(state)) &&
-      Optional(ParseRefQualifier(state)) && ParsePrefix(state) &&
-      LeaveNestedName(state, copy.nest_level) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// This part is tricky.  If we literally translate them to code, we'll
-// end up infinite loop.  Hence we merge them to avoid the case.
-//
-// <prefix> ::= <prefix> <unqualified-name>
-//          ::= <template-prefix> <template-args>
-//          ::= <template-param>
-//          ::= <substitution>
-//          ::= # empty
-// <template-prefix> ::= <prefix> <(template) unqualified-name>
-//                   ::= <template-param>
-//                   ::= <substitution>
-static bool ParsePrefix(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  bool has_something = false;
-  while (true) {
-    MaybeAppendSeparator(state);
-    if (ParseTemplateParam(state) ||
-        ParseSubstitution(state, /*accept_std=*/true) ||
-        ParseUnscopedName(state) ||
-        (ParseOneCharToken(state, 'M') && ParseUnnamedTypeName(state))) {
-      has_something = true;
-      MaybeIncreaseNestLevel(state);
-      continue;
-    }
-    MaybeCancelLastSeparator(state);
-    if (has_something && ParseTemplateArgs(state)) {
-      return ParsePrefix(state);
-    } else {
-      break;
-    }
-  }
-  return true;
-}
-
-// <unqualified-name> ::= <operator-name>
-//                    ::= <ctor-dtor-name>
-//                    ::= <source-name>
-//                    ::= <local-source-name> // GCC extension; see below.
-//                    ::= <unnamed-type-name>
-static bool ParseUnqualifiedName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  return (ParseOperatorName(state, nullptr) || ParseCtorDtorName(state) ||
-          ParseSourceName(state) || ParseLocalSourceName(state) ||
-          ParseUnnamedTypeName(state));
-}
-
-// <source-name> ::= <positive length number> <identifier>
-static bool ParseSourceName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  int length = -1;
-  if (ParseNumber(state, &length) && ParseIdentifier(state, length)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <local-source-name> ::= L <source-name> [<discriminator>]
-//
-// References:
-//   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31775
-//   https://gcc.gnu.org/viewcvs?view=rev&revision=124467
-static bool ParseLocalSourceName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'L') && ParseSourceName(state) &&
-      Optional(ParseDiscriminator(state))) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <unnamed-type-name> ::= Ut [<(nonnegative) number>] _
-//                     ::= <closure-type-name>
-// <closure-type-name> ::= Ul <lambda-sig> E [<(nonnegative) number>] _
-// <lambda-sig>        ::= <(parameter) type>+
-static bool ParseUnnamedTypeName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  // Type's 1-based index n is encoded as { "", n == 1; itoa(n-2), otherwise }.
-  // Optionally parse the encoded value into 'which' and add 2 to get the index.
-  int which = -1;
-
-  // Unnamed type local to function or class.
-  if (ParseTwoCharToken(state, "Ut") && Optional(ParseNumber(state, &which)) &&
-      which <= std::numeric_limits<int>::max() - 2 &&  // Don't overflow.
-      ParseOneCharToken(state, '_')) {
-    MaybeAppend(state, "{unnamed type#");
-    MaybeAppendDecimal(state, 2 + which);
-    MaybeAppend(state, "}");
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Closure type.
-  which = -1;
-  if (ParseTwoCharToken(state, "Ul") && DisableAppend(state) &&
-      OneOrMore(ParseType, state) && RestoreAppend(state, copy.append) &&
-      ParseOneCharToken(state, 'E') && Optional(ParseNumber(state, &which)) &&
-      which <= std::numeric_limits<int>::max() - 2 &&  // Don't overflow.
-      ParseOneCharToken(state, '_')) {
-    MaybeAppend(state, "{lambda()#");
-    MaybeAppendDecimal(state, 2 + which);
-    MaybeAppend(state, "}");
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <number> ::= [n] <non-negative decimal integer>
-// If "number_out" is non-null, then *number_out is set to the value of the
-// parsed number on success.
-static bool ParseNumber(State *state, int *number_out) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  bool negative = false;
-  if (ParseOneCharToken(state, 'n')) {
-    negative = true;
-  }
-  const char *p = RemainingInput(state);
-  uint64_t number = 0;
-  for (; *p != '\0'; ++p) {
-    if (IsDigit(*p)) {
-      number = number * 10 + (*p - '0');
-    } else {
-      break;
-    }
-  }
-  // Apply the sign with uint64_t arithmetic so overflows aren't UB.  Gives
-  // "incorrect" results for out-of-range inputs, but negative values only
-  // appear for literals, which aren't printed.
-  if (negative) {
-    number = ~number + 1;
-  }
-  if (p != RemainingInput(state)) {  // Conversion succeeded.
-    state->parse_state.mangled_idx += p - RemainingInput(state);
-    if (number_out != nullptr) {
-      // Note: possibly truncate "number".
-      *number_out = number;
-    }
-    return true;
-  }
-  return false;
-}
-
-// Floating-point literals are encoded using a fixed-length lowercase
-// hexadecimal string.
-static bool ParseFloatNumber(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  const char *p = RemainingInput(state);
-  for (; *p != '\0'; ++p) {
-    if (!IsDigit(*p) && !(*p >= 'a' && *p <= 'f')) {
-      break;
-    }
-  }
-  if (p != RemainingInput(state)) {  // Conversion succeeded.
-    state->parse_state.mangled_idx += p - RemainingInput(state);
-    return true;
-  }
-  return false;
-}
-
-// The <seq-id> is a sequence number in base 36,
-// using digits and upper case letters
-static bool ParseSeqId(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  const char *p = RemainingInput(state);
-  for (; *p != '\0'; ++p) {
-    if (!IsDigit(*p) && !(*p >= 'A' && *p <= 'Z')) {
-      break;
-    }
-  }
-  if (p != RemainingInput(state)) {  // Conversion succeeded.
-    state->parse_state.mangled_idx += p - RemainingInput(state);
-    return true;
-  }
-  return false;
-}
-
-// <identifier> ::= <unqualified source code identifier> (of given length)
-static bool ParseIdentifier(State *state, int length) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (length < 0 || !AtLeastNumCharsRemaining(RemainingInput(state), length)) {
-    return false;
-  }
-  if (IdentifierIsAnonymousNamespace(state, length)) {
-    MaybeAppend(state, "(anonymous namespace)");
-  } else {
-    MaybeAppendWithLength(state, RemainingInput(state), length);
-  }
-  state->parse_state.mangled_idx += length;
-  return true;
-}
-
-// <operator-name> ::= nw, and other two letters cases
-//                 ::= cv <type>  # (cast)
-//                 ::= v  <digit> <source-name> # vendor extended operator
-static bool ParseOperatorName(State *state, int *arity) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (!AtLeastNumCharsRemaining(RemainingInput(state), 2)) {
-    return false;
-  }
-  // First check with "cv" (cast) case.
-  ParseState copy = state->parse_state;
-  if (ParseTwoCharToken(state, "cv") && MaybeAppend(state, "operator ") &&
-      EnterNestedName(state) && ParseType(state) &&
-      LeaveNestedName(state, copy.nest_level)) {
-    if (arity != nullptr) {
-      *arity = 1;
-    }
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Then vendor extended operators.
-  if (ParseOneCharToken(state, 'v') && ParseDigit(state, arity) &&
-      ParseSourceName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Other operator names should start with a lower alphabet followed
-  // by a lower/upper alphabet.
-  if (!(IsLower(RemainingInput(state)[0]) &&
-        IsAlpha(RemainingInput(state)[1]))) {
-    return false;
-  }
-  // We may want to perform a binary search if we really need speed.
-  const AbbrevPair *p;
-  for (p = kOperatorList; p->abbrev != nullptr; ++p) {
-    if (RemainingInput(state)[0] == p->abbrev[0] &&
-        RemainingInput(state)[1] == p->abbrev[1]) {
-      if (arity != nullptr) {
-        *arity = p->arity;
-      }
-      MaybeAppend(state, "operator");
-      if (IsLower(*p->real_name)) {  // new, delete, etc.
-        MaybeAppend(state, " ");
-      }
-      MaybeAppend(state, p->real_name);
-      state->parse_state.mangled_idx += 2;
-      return true;
-    }
-  }
-  return false;
-}
-
-// <special-name> ::= TV <type>
-//                ::= TT <type>
-//                ::= TI <type>
-//                ::= TS <type>
-//                ::= TH <type>  # thread-local
-//                ::= Tc <call-offset> <call-offset> <(base) encoding>
-//                ::= GV <(object) name>
-//                ::= T <call-offset> <(base) encoding>
-// G++ extensions:
-//                ::= TC <type> <(offset) number> _ <(base) type>
-//                ::= TF <type>
-//                ::= TJ <type>
-//                ::= GR <name>
-//                ::= GA <encoding>
-//                ::= Th <call-offset> <(base) encoding>
-//                ::= Tv <call-offset> <(base) encoding>
-//
-// Note: we don't care much about them since they don't appear in
-// stack traces.  The are special data.
-static bool ParseSpecialName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "VTISH") &&
-      ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "Tc") && ParseCallOffset(state) &&
-      ParseCallOffset(state) && ParseEncoding(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "GV") && ParseName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'T') && ParseCallOffset(state) &&
-      ParseEncoding(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // G++ extensions
-  if (ParseTwoCharToken(state, "TC") && ParseType(state) &&
-      ParseNumber(state, nullptr) && ParseOneCharToken(state, '_') &&
-      DisableAppend(state) && ParseType(state)) {
-    RestoreAppend(state, copy.append);
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "FJ") &&
-      ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "GR") && ParseName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "GA") && ParseEncoding(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "hv") &&
-      ParseCallOffset(state) && ParseEncoding(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <call-offset> ::= h <nv-offset> _
-//               ::= v <v-offset> _
-static bool ParseCallOffset(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'h') && ParseNVOffset(state) &&
-      ParseOneCharToken(state, '_')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'v') && ParseVOffset(state) &&
-      ParseOneCharToken(state, '_')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <nv-offset> ::= <(offset) number>
-static bool ParseNVOffset(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  return ParseNumber(state, nullptr);
-}
-
-// <v-offset>  ::= <(offset) number> _ <(virtual offset) number>
-static bool ParseVOffset(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseNumber(state, nullptr) && ParseOneCharToken(state, '_') &&
-      ParseNumber(state, nullptr)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <ctor-dtor-name> ::= C1 | C2 | C3 | CI1 <base-class-type> | CI2
-// <base-class-type>
-//                  ::= D0 | D1 | D2
-// # GCC extensions: "unified" constructor/destructor.  See
-// #
-// https://github.com/gcc-mirror/gcc/blob/7ad17b583c3643bd4557f29b8391ca7ef08391f5/gcc/cp/mangle.c#L1847
-//                  ::= C4 | D4
-static bool ParseCtorDtorName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'C')) {
-    if (ParseCharClass(state, "1234")) {
-      const char *const prev_name =
-          state->out + state->parse_state.prev_name_idx;
-      MaybeAppendWithLength(state, prev_name,
-                            state->parse_state.prev_name_length);
-      return true;
-    } else if (ParseOneCharToken(state, 'I') && ParseCharClass(state, "12") &&
-               ParseClassEnumType(state)) {
-      return true;
-    }
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'D') && ParseCharClass(state, "0124")) {
-    const char *const prev_name = state->out + state->parse_state.prev_name_idx;
-    MaybeAppend(state, "~");
-    MaybeAppendWithLength(state, prev_name,
-                          state->parse_state.prev_name_length);
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <decltype> ::= Dt <expression> E  # decltype of an id-expression or class
-//                                   # member access (C++0x)
-//            ::= DT <expression> E  # decltype of an expression (C++0x)
-static bool ParseDecltype(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'D') && ParseCharClass(state, "tT") &&
-      ParseExpression(state) && ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <type> ::= <CV-qualifiers> <type>
-//        ::= P <type>   # pointer-to
-//        ::= R <type>   # reference-to
-//        ::= O <type>   # rvalue reference-to (C++0x)
-//        ::= C <type>   # complex pair (C 2000)
-//        ::= G <type>   # imaginary (C 2000)
-//        ::= U <source-name> <type>  # vendor extended type qualifier
-//        ::= <builtin-type>
-//        ::= <function-type>
-//        ::= <class-enum-type>  # note: just an alias for <name>
-//        ::= <array-type>
-//        ::= <pointer-to-member-type>
-//        ::= <template-template-param> <template-args>
-//        ::= <template-param>
-//        ::= <decltype>
-//        ::= <substitution>
-//        ::= Dp <type>          # pack expansion of (C++0x)
-//        ::= Dv <num-elems> _   # GNU vector extension
-//
-static bool ParseType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-
-  // We should check CV-qualifers, and PRGC things first.
-  //
-  // CV-qualifiers overlap with some operator names, but an operator name is not
-  // valid as a type.  To avoid an ambiguity that can lead to exponential time
-  // complexity, refuse to backtrack the CV-qualifiers.
-  //
-  // _Z4aoeuIrMvvE
-  //  => _Z 4aoeuI        rM  v     v   E
-  //         aoeu<operator%=, void, void>
-  //  => _Z 4aoeuI r Mv v              E
-  //         aoeu<void void::* restrict>
-  //
-  // By consuming the CV-qualifiers first, the former parse is disabled.
-  if (ParseCVQualifiers(state)) {
-    const bool result = ParseType(state);
-    if (!result) state->parse_state = copy;
-    return result;
-  }
-  state->parse_state = copy;
-
-  // Similarly, these tag characters can overlap with other <name>s resulting in
-  // two different parse prefixes that land on <template-args> in the same
-  // place, such as "C3r1xI...".  So, disable the "ctor-name = C3" parse by
-  // refusing to backtrack the tag characters.
-  if (ParseCharClass(state, "OPRCG")) {
-    const bool result = ParseType(state);
-    if (!result) state->parse_state = copy;
-    return result;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "Dp") && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'U') && ParseSourceName(state) &&
-      ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseBuiltinType(state) || ParseFunctionType(state) ||
-      ParseClassEnumType(state) || ParseArrayType(state) ||
-      ParsePointerToMemberType(state) || ParseDecltype(state) ||
-      // "std" on its own isn't a type.
-      ParseSubstitution(state, /*accept_std=*/false)) {
-    return true;
-  }
-
-  if (ParseTemplateTemplateParam(state) && ParseTemplateArgs(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Less greedy than <template-template-param> <template-args>.
-  if (ParseTemplateParam(state)) {
-    return true;
-  }
-
-  if (ParseTwoCharToken(state, "Dv") && ParseNumber(state, nullptr) &&
-      ParseOneCharToken(state, '_')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <CV-qualifiers> ::= [r] [V] [K]
-// We don't allow empty <CV-qualifiers> to avoid infinite loop in
-// ParseType().
-static bool ParseCVQualifiers(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  int num_cv_qualifiers = 0;
-  num_cv_qualifiers += ParseOneCharToken(state, 'r');
-  num_cv_qualifiers += ParseOneCharToken(state, 'V');
-  num_cv_qualifiers += ParseOneCharToken(state, 'K');
-  return num_cv_qualifiers > 0;
-}
-
-// <builtin-type> ::= v, etc.  # single-character builtin types
-//                ::= u <source-name>
-//                ::= Dd, etc.  # two-character builtin types
-//
-// Not supported:
-//                ::= DF <number> _ # _FloatN (N bits)
-//
-static bool ParseBuiltinType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  const AbbrevPair *p;
-  for (p = kBuiltinTypeList; p->abbrev != nullptr; ++p) {
-    // Guaranteed only 1- or 2-character strings in kBuiltinTypeList.
-    if (p->abbrev[1] == '\0') {
-      if (ParseOneCharToken(state, p->abbrev[0])) {
-        MaybeAppend(state, p->real_name);
-        return true;
-      }
-    } else if (p->abbrev[2] == '\0' && ParseTwoCharToken(state, p->abbrev)) {
-      MaybeAppend(state, p->real_name);
-      return true;
-    }
-  }
-
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'u') && ParseSourceName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-//  <exception-spec> ::= Do                # non-throwing
-//                                           exception-specification (e.g.,
-//                                           noexcept, throw())
-//                   ::= DO <expression> E # computed (instantiation-dependent)
-//                                           noexcept
-//                   ::= Dw <type>+ E      # dynamic exception specification
-//                                           with instantiation-dependent types
-static bool ParseExceptionSpec(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-
-  if (ParseTwoCharToken(state, "Do")) return true;
-
-  ParseState copy = state->parse_state;
-  if (ParseTwoCharToken(state, "DO") && ParseExpression(state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-  if (ParseTwoCharToken(state, "Dw") && OneOrMore(ParseType, state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <function-type> ::= [exception-spec] F [Y] <bare-function-type> [O] E
-static bool ParseFunctionType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (Optional(ParseExceptionSpec(state)) && ParseOneCharToken(state, 'F') &&
-      Optional(ParseOneCharToken(state, 'Y')) && ParseBareFunctionType(state) &&
-      Optional(ParseOneCharToken(state, 'O')) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <bare-function-type> ::= <(signature) type>+
-static bool ParseBareFunctionType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  DisableAppend(state);
-  if (OneOrMore(ParseType, state)) {
-    RestoreAppend(state, copy.append);
-    MaybeAppend(state, "()");
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <class-enum-type> ::= <name>
-static bool ParseClassEnumType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  return ParseName(state);
-}
-
-// <array-type> ::= A <(positive dimension) number> _ <(element) type>
-//              ::= A [<(dimension) expression>] _ <(element) type>
-static bool ParseArrayType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'A') && ParseNumber(state, nullptr) &&
-      ParseOneCharToken(state, '_') && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'A') && Optional(ParseExpression(state)) &&
-      ParseOneCharToken(state, '_') && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <pointer-to-member-type> ::= M <(class) type> <(member) type>
-static bool ParsePointerToMemberType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'M') && ParseType(state) && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <template-param> ::= T_
-//                  ::= T <parameter-2 non-negative number> _
-static bool ParseTemplateParam(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseTwoCharToken(state, "T_")) {
-    MaybeAppend(state, "?");  // We don't support template substitutions.
-    return true;
-  }
-
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'T') && ParseNumber(state, nullptr) &&
-      ParseOneCharToken(state, '_')) {
-    MaybeAppend(state, "?");  // We don't support template substitutions.
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <template-template-param> ::= <template-param>
-//                           ::= <substitution>
-static bool ParseTemplateTemplateParam(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  return (ParseTemplateParam(state) ||
-          // "std" on its own isn't a template.
-          ParseSubstitution(state, /*accept_std=*/false));
-}
-
-// <template-args> ::= I <template-arg>+ E
-static bool ParseTemplateArgs(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  DisableAppend(state);
-  if (ParseOneCharToken(state, 'I') && OneOrMore(ParseTemplateArg, state) &&
-      ParseOneCharToken(state, 'E')) {
-    RestoreAppend(state, copy.append);
-    MaybeAppend(state, "<>");
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <template-arg>  ::= <type>
-//                 ::= <expr-primary>
-//                 ::= J <template-arg>* E        # argument pack
-//                 ::= X <expression> E
-static bool ParseTemplateArg(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'J') && ZeroOrMore(ParseTemplateArg, state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // There can be significant overlap between the following leading to
-  // exponential backtracking:
-  //
-  //   <expr-primary> ::= L <type> <expr-cast-value> E
-  //                 e.g. L 2xxIvE 1                 E
-  //   <type>         ==> <local-source-name> <template-args>
-  //                 e.g. L 2xx               IvE
-  //
-  // This means parsing an entire <type> twice, and <type> can contain
-  // <template-arg>, so this can generate exponential backtracking.  There is
-  // only overlap when the remaining input starts with "L <source-name>", so
-  // parse all cases that can start this way jointly to share the common prefix.
-  //
-  // We have:
-  //
-  //   <template-arg> ::= <type>
-  //                  ::= <expr-primary>
-  //
-  // First, drop all the productions of <type> that must start with something
-  // other than 'L'.  All that's left is <class-enum-type>; inline it.
-  //
-  //   <type> ::= <nested-name> # starts with 'N'
-  //          ::= <unscoped-name>
-  //          ::= <unscoped-template-name> <template-args>
-  //          ::= <local-name> # starts with 'Z'
-  //
-  // Drop and inline again:
-  //
-  //   <type> ::= <unscoped-name>
-  //          ::= <unscoped-name> <template-args>
-  //          ::= <substitution> <template-args> # starts with 'S'
-  //
-  // Merge the first two, inline <unscoped-name>, drop last:
-  //
-  //   <type> ::= <unqualified-name> [<template-args>]
-  //          ::= St <unqualified-name> [<template-args>] # starts with 'S'
-  //
-  // Drop and inline:
-  //
-  //   <type> ::= <operator-name> [<template-args>] # starts with lowercase
-  //          ::= <ctor-dtor-name> [<template-args>] # starts with 'C' or 'D'
-  //          ::= <source-name> [<template-args>] # starts with digit
-  //          ::= <local-source-name> [<template-args>]
-  //          ::= <unnamed-type-name> [<template-args>] # starts with 'U'
-  //
-  // One more time:
-  //
-  //   <type> ::= L <source-name> [<template-args>]
-  //
-  // Likewise with <expr-primary>:
-  //
-  //   <expr-primary> ::= L <type> <expr-cast-value> E
-  //                  ::= LZ <encoding> E # cannot overlap; drop
-  //                  ::= L <mangled_name> E # cannot overlap; drop
-  //
-  // By similar reasoning as shown above, the only <type>s starting with
-  // <source-name> are "<source-name> [<template-args>]".  Inline this.
-  //
-  //   <expr-primary> ::= L <source-name> [<template-args>] <expr-cast-value> E
-  //
-  // Now inline both of these into <template-arg>:
-  //
-  //   <template-arg> ::= L <source-name> [<template-args>]
-  //                  ::= L <source-name> [<template-args>] <expr-cast-value> E
-  //
-  // Merge them and we're done:
-  //   <template-arg>
-  //     ::= L <source-name> [<template-args>] [<expr-cast-value> E]
-  if (ParseLocalSourceName(state) && Optional(ParseTemplateArgs(state))) {
-    copy = state->parse_state;
-    if (ParseExprCastValue(state) && ParseOneCharToken(state, 'E')) {
-      return true;
-    }
-    state->parse_state = copy;
-    return true;
-  }
-
-  // Now that the overlapping cases can't reach this code, we can safely call
-  // both of these.
-  if (ParseType(state) || ParseExprPrimary(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'X') && ParseExpression(state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <unresolved-type> ::= <template-param> [<template-args>]
-//                   ::= <decltype>
-//                   ::= <substitution>
-static inline bool ParseUnresolvedType(State *state) {
-  // No ComplexityGuard because we don't copy the state in this stack frame.
-  return (ParseTemplateParam(state) && Optional(ParseTemplateArgs(state))) ||
-         ParseDecltype(state) || ParseSubstitution(state, /*accept_std=*/false);
-}
-
-// <simple-id> ::= <source-name> [<template-args>]
-static inline bool ParseSimpleId(State *state) {
-  // No ComplexityGuard because we don't copy the state in this stack frame.
-
-  // Note: <simple-id> cannot be followed by a parameter pack; see comment in
-  // ParseUnresolvedType.
-  return ParseSourceName(state) && Optional(ParseTemplateArgs(state));
-}
-
-// <base-unresolved-name> ::= <source-name> [<template-args>]
-//                        ::= on <operator-name> [<template-args>]
-//                        ::= dn <destructor-name>
-static bool ParseBaseUnresolvedName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-
-  if (ParseSimpleId(state)) {
-    return true;
-  }
-
-  ParseState copy = state->parse_state;
-  if (ParseTwoCharToken(state, "on") && ParseOperatorName(state, nullptr) &&
-      Optional(ParseTemplateArgs(state))) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "dn") &&
-      (ParseUnresolvedType(state) || ParseSimpleId(state))) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <unresolved-name> ::= [gs] <base-unresolved-name>
-//                   ::= sr <unresolved-type> <base-unresolved-name>
-//                   ::= srN <unresolved-type> <unresolved-qualifier-level>+ E
-//                         <base-unresolved-name>
-//                   ::= [gs] sr <unresolved-qualifier-level>+ E
-//                         <base-unresolved-name>
-static bool ParseUnresolvedName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-
-  ParseState copy = state->parse_state;
-  if (Optional(ParseTwoCharToken(state, "gs")) &&
-      ParseBaseUnresolvedName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "sr") && ParseUnresolvedType(state) &&
-      ParseBaseUnresolvedName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "sr") && ParseOneCharToken(state, 'N') &&
-      ParseUnresolvedType(state) &&
-      OneOrMore(/* <unresolved-qualifier-level> ::= */ ParseSimpleId, state) &&
-      ParseOneCharToken(state, 'E') && ParseBaseUnresolvedName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (Optional(ParseTwoCharToken(state, "gs")) &&
-      ParseTwoCharToken(state, "sr") &&
-      OneOrMore(/* <unresolved-qualifier-level> ::= */ ParseSimpleId, state) &&
-      ParseOneCharToken(state, 'E') && ParseBaseUnresolvedName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <expression> ::= <1-ary operator-name> <expression>
-//              ::= <2-ary operator-name> <expression> <expression>
-//              ::= <3-ary operator-name> <expression> <expression> <expression>
-//              ::= cl <expression>+ E
-//              ::= cv <type> <expression>      # type (expression)
-//              ::= cv <type> _ <expression>* E # type (expr-list)
-//              ::= st <type>
-//              ::= <template-param>
-//              ::= <function-param>
-//              ::= <expr-primary>
-//              ::= dt <expression> <unresolved-name> # expr.name
-//              ::= pt <expression> <unresolved-name> # expr->name
-//              ::= sp <expression>         # argument pack expansion
-//              ::= sr <type> <unqualified-name> <template-args>
-//              ::= sr <type> <unqualified-name>
-// <function-param> ::= fp <(top-level) CV-qualifiers> _
-//                  ::= fp <(top-level) CV-qualifiers> <number> _
-//                  ::= fL <number> p <(top-level) CV-qualifiers> _
-//                  ::= fL <number> p <(top-level) CV-qualifiers> <number> _
-static bool ParseExpression(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseTemplateParam(state) || ParseExprPrimary(state)) {
-    return true;
-  }
-
-  // Object/function call expression.
-  ParseState copy = state->parse_state;
-  if (ParseTwoCharToken(state, "cl") && OneOrMore(ParseExpression, state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Function-param expression (level 0).
-  if (ParseTwoCharToken(state, "fp") && Optional(ParseCVQualifiers(state)) &&
-      Optional(ParseNumber(state, nullptr)) && ParseOneCharToken(state, '_')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Function-param expression (level 1+).
-  if (ParseTwoCharToken(state, "fL") && Optional(ParseNumber(state, nullptr)) &&
-      ParseOneCharToken(state, 'p') && Optional(ParseCVQualifiers(state)) &&
-      Optional(ParseNumber(state, nullptr)) && ParseOneCharToken(state, '_')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Parse the conversion expressions jointly to avoid re-parsing the <type> in
-  // their common prefix.  Parsed as:
-  // <expression> ::= cv <type> <conversion-args>
-  // <conversion-args> ::= _ <expression>* E
-  //                   ::= <expression>
-  //
-  // Also don't try ParseOperatorName after seeing "cv", since ParseOperatorName
-  // also needs to accept "cv <type>" in other contexts.
-  if (ParseTwoCharToken(state, "cv")) {
-    if (ParseType(state)) {
-      ParseState copy2 = state->parse_state;
-      if (ParseOneCharToken(state, '_') && ZeroOrMore(ParseExpression, state) &&
-          ParseOneCharToken(state, 'E')) {
-        return true;
-      }
-      state->parse_state = copy2;
-      if (ParseExpression(state)) {
-        return true;
-      }
-    }
-  } else {
-    // Parse unary, binary, and ternary operator expressions jointly, taking
-    // care not to re-parse subexpressions repeatedly. Parse like:
-    //   <expression> ::= <operator-name> <expression>
-    //                    [<one-to-two-expressions>]
-    //   <one-to-two-expressions> ::= <expression> [<expression>]
-    int arity = -1;
-    if (ParseOperatorName(state, &arity) &&
-        arity > 0 &&  // 0 arity => disabled.
-        (arity < 3 || ParseExpression(state)) &&
-        (arity < 2 || ParseExpression(state)) &&
-        (arity < 1 || ParseExpression(state))) {
-      return true;
-    }
-  }
-  state->parse_state = copy;
-
-  // sizeof type
-  if (ParseTwoCharToken(state, "st") && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Object and pointer member access expressions.
-  if ((ParseTwoCharToken(state, "dt") || ParseTwoCharToken(state, "pt")) &&
-      ParseExpression(state) && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Pointer-to-member access expressions.  This parses the same as a binary
-  // operator, but it's implemented separately because "ds" shouldn't be
-  // accepted in other contexts that parse an operator name.
-  if (ParseTwoCharToken(state, "ds") && ParseExpression(state) &&
-      ParseExpression(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Parameter pack expansion
-  if (ParseTwoCharToken(state, "sp") && ParseExpression(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return ParseUnresolvedName(state);
-}
-
-// <expr-primary> ::= L <type> <(value) number> E
-//                ::= L <type> <(value) float> E
-//                ::= L <mangled-name> E
-//                // A bug in g++'s C++ ABI version 2 (-fabi-version=2).
-//                ::= LZ <encoding> E
-//
-// Warning, subtle: the "bug" LZ production above is ambiguous with the first
-// production where <type> starts with <local-name>, which can lead to
-// exponential backtracking in two scenarios:
-//
-// - When whatever follows the E in the <local-name> in the first production is
-//   not a name, we backtrack the whole <encoding> and re-parse the whole thing.
-//
-// - When whatever follows the <local-name> in the first production is not a
-//   number and this <expr-primary> may be followed by a name, we backtrack the
-//   <name> and re-parse it.
-//
-// Moreover this ambiguity isn't always resolved -- for example, the following
-// has two different parses:
-//
-//   _ZaaILZ4aoeuE1x1EvE
-//   => operator&&<aoeu, x, E, void>
-//   => operator&&<(aoeu::x)(1), void>
-//
-// To resolve this, we just do what GCC's demangler does, and refuse to parse
-// casts to <local-name> types.
-static bool ParseExprPrimary(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-
-  // The "LZ" special case: if we see LZ, we commit to accept "LZ <encoding> E"
-  // or fail, no backtracking.
-  if (ParseTwoCharToken(state, "LZ")) {
-    if (ParseEncoding(state) && ParseOneCharToken(state, 'E')) {
-      return true;
-    }
-
-    state->parse_state = copy;
-    return false;
-  }
-
-  // The merged cast production.
-  if (ParseOneCharToken(state, 'L') && ParseType(state) &&
-      ParseExprCastValue(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'L') && ParseMangledName(state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <number> or <float>, followed by 'E', as described above ParseExprPrimary.
-static bool ParseExprCastValue(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  // We have to be able to backtrack after accepting a number because we could
-  // have e.g. "7fffE", which will accept "7" as a number but then fail to find
-  // the 'E'.
-  ParseState copy = state->parse_state;
-  if (ParseNumber(state, nullptr) && ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseFloatNumber(state) && ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <local-name> ::= Z <(function) encoding> E <(entity) name> [<discriminator>]
-//              ::= Z <(function) encoding> E s [<discriminator>]
-//
-// Parsing a common prefix of these two productions together avoids an
-// exponential blowup of backtracking.  Parse like:
-//   <local-name> := Z <encoding> E <local-name-suffix>
-//   <local-name-suffix> ::= s [<discriminator>]
-//                       ::= <name> [<discriminator>]
-
-static bool ParseLocalNameSuffix(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-
-  if (MaybeAppend(state, "::") && ParseName(state) &&
-      Optional(ParseDiscriminator(state))) {
-    return true;
-  }
-
-  // Since we're not going to overwrite the above "::" by re-parsing the
-  // <encoding> (whose trailing '\0' byte was in the byte now holding the
-  // first ':'), we have to rollback the "::" if the <name> parse failed.
-  if (state->parse_state.append) {
-    state->out[state->parse_state.out_cur_idx - 2] = '\0';
-  }
-
-  return ParseOneCharToken(state, 's') && Optional(ParseDiscriminator(state));
-}
-
-static bool ParseLocalName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'Z') && ParseEncoding(state) &&
-      ParseOneCharToken(state, 'E') && ParseLocalNameSuffix(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <discriminator> := _ <(non-negative) number>
-static bool ParseDiscriminator(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, '_') && ParseNumber(state, nullptr)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <substitution> ::= S_
-//                ::= S <seq-id> _
-//                ::= St, etc.
-//
-// "St" is special in that it's not valid as a standalone name, and it *is*
-// allowed to precede a name without being wrapped in "N...E".  This means that
-// if we accept it on its own, we can accept "St1a" and try to parse
-// template-args, then fail and backtrack, accept "St" on its own, then "1a" as
-// an unqualified name and re-parse the same template-args.  To block this
-// exponential backtracking, we disable it with 'accept_std=false' in
-// problematic contexts.
-static bool ParseSubstitution(State *state, bool accept_std) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseTwoCharToken(state, "S_")) {
-    MaybeAppend(state, "?");  // We don't support substitutions.
-    return true;
-  }
-
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'S') && ParseSeqId(state) &&
-      ParseOneCharToken(state, '_')) {
-    MaybeAppend(state, "?");  // We don't support substitutions.
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Expand abbreviations like "St" => "std".
-  if (ParseOneCharToken(state, 'S')) {
-    const AbbrevPair *p;
-    for (p = kSubstitutionList; p->abbrev != nullptr; ++p) {
-      if (RemainingInput(state)[0] == p->abbrev[1] &&
-          (accept_std || p->abbrev[1] != 't')) {
-        MaybeAppend(state, "std");
-        if (p->real_name[0] != '\0') {
-          MaybeAppend(state, "::");
-          MaybeAppend(state, p->real_name);
-        }
-        ++state->parse_state.mangled_idx;
-        return true;
-      }
-    }
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// Parse <mangled-name>, optionally followed by either a function-clone suffix
-// or version suffix.  Returns true only if all of "mangled_cur" was consumed.
-static bool ParseTopLevelMangledName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseMangledName(state)) {
-    if (RemainingInput(state)[0] != '\0') {
-      // Drop trailing function clone suffix, if any.
-      if (IsFunctionCloneSuffix(RemainingInput(state))) {
-        return true;
-      }
-      // Append trailing version suffix if any.
-      // ex. _Z3foo@@GLIBCXX_3.4
-      if (RemainingInput(state)[0] == '@') {
-        MaybeAppend(state, RemainingInput(state));
-        return true;
-      }
-      return false;  // Unconsumed suffix.
-    }
-    return true;
-  }
-  return false;
-}
-
-static bool Overflowed(const State *state) {
-  return state->parse_state.out_cur_idx >= state->out_end_idx;
-}
-
-// The demangler entry point.
-bool Demangle(const char *mangled, char *out, int out_size) {
-  State state;
-  InitState(&state, mangled, out, out_size);
-  return ParseTopLevelMangledName(&state) && !Overflowed(&state) &&
-         state.parse_state.out_cur_idx > 0;
-}
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
diff --git a/third_party/abseil_cpp/absl/debugging/internal/demangle.h b/third_party/abseil_cpp/absl/debugging/internal/demangle.h
deleted file mode 100644
index c314d9bc237c..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/demangle.h
+++ /dev/null
@@ -1,71 +0,0 @@
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// An async-signal-safe and thread-safe demangler for Itanium C++ ABI
-// (aka G++ V3 ABI).
-//
-// The demangler is implemented to be used in async signal handlers to
-// symbolize stack traces.  We cannot use libstdc++'s
-// abi::__cxa_demangle() in such signal handlers since it's not async
-// signal safe (it uses malloc() internally).
-//
-// Note that this demangler doesn't support full demangling.  More
-// specifically, it doesn't print types of function parameters and
-// types of template arguments.  It just skips them.  However, it's
-// still very useful to extract basic information such as class,
-// function, constructor, destructor, and operator names.
-//
-// See the implementation note in demangle.cc if you are interested.
-//
-// Example:
-//
-// | Mangled Name  | The Demangler | abi::__cxa_demangle()
-// |---------------|---------------|-----------------------
-// | _Z1fv         | f()           | f()
-// | _Z1fi         | f()           | f(int)
-// | _Z3foo3bar    | foo()         | foo(bar)
-// | _Z1fIiEvi     | f<>()         | void f<int>(int)
-// | _ZN1N1fE      | N::f          | N::f
-// | _ZN3Foo3BarEv | Foo::Bar()    | Foo::Bar()
-// | _Zrm1XS_"     | operator%()   | operator%(X, X)
-// | _ZN3FooC1Ev   | Foo::Foo()    | Foo::Foo()
-// | _Z1fSs        | f()           | f(std::basic_string<char,
-// |               |               |   std::char_traits<char>,
-// |               |               |   std::allocator<char> >)
-//
-// See the unit test for more examples.
-//
-// Note: we might want to write demanglers for ABIs other than Itanium
-// C++ ABI in the future.
-//
-
-#ifndef ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_
-#define ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_
-
-#include "absl/base/config.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-// Demangle `mangled`.  On success, return true and write the
-// demangled symbol name to `out`.  Otherwise, return false.
-// `out` is modified even if demangling is unsuccessful.
-bool Demangle(const char *mangled, char *out, int out_size);
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/demangle_test.cc b/third_party/abseil_cpp/absl/debugging/internal/demangle_test.cc
deleted file mode 100644
index 0bed7359d8b4..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/demangle_test.cc
+++ /dev/null
@@ -1,197 +0,0 @@
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#include "absl/debugging/internal/demangle.h"
-
-#include <cstdlib>
-#include <string>
-
-#include "gtest/gtest.h"
-#include "absl/base/config.h"
-#include "absl/base/internal/raw_logging.h"
-#include "absl/debugging/internal/stack_consumption.h"
-#include "absl/memory/memory.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-namespace {
-
-// A wrapper function for Demangle() to make the unit test simple.
-static const char *DemangleIt(const char * const mangled) {
-  static char demangled[4096];
-  if (Demangle(mangled, demangled, sizeof(demangled))) {
-    return demangled;
-  } else {
-    return mangled;
-  }
-}
-
-// Test corner cases of bounary conditions.
-TEST(Demangle, CornerCases) {
-  char tmp[10];
-  EXPECT_TRUE(Demangle("_Z6foobarv", tmp, sizeof(tmp)));
-  // sizeof("foobar()") == 9
-  EXPECT_STREQ("foobar()", tmp);
-  EXPECT_TRUE(Demangle("_Z6foobarv", tmp, 9));
-  EXPECT_STREQ("foobar()", tmp);
-  EXPECT_FALSE(Demangle("_Z6foobarv", tmp, 8));  // Not enough.
-  EXPECT_FALSE(Demangle("_Z6foobarv", tmp, 1));
-  EXPECT_FALSE(Demangle("_Z6foobarv", tmp, 0));
-  EXPECT_FALSE(Demangle("_Z6foobarv", nullptr, 0));  // Should not cause SEGV.
-  EXPECT_FALSE(Demangle("_Z1000000", tmp, 9));
-}
-
-// Test handling of functions suffixed with .clone.N, which is used
-// by GCC 4.5.x (and our locally-modified version of GCC 4.4.x), and
-// .constprop.N and .isra.N, which are used by GCC 4.6.x.  These
-// suffixes are used to indicate functions which have been cloned
-// during optimization.  We ignore these suffixes.
-TEST(Demangle, Clones) {
-  char tmp[20];
-  EXPECT_TRUE(Demangle("_ZL3Foov", tmp, sizeof(tmp)));
-  EXPECT_STREQ("Foo()", tmp);
-  EXPECT_TRUE(Demangle("_ZL3Foov.clone.3", tmp, sizeof(tmp)));
-  EXPECT_STREQ("Foo()", tmp);
-  EXPECT_TRUE(Demangle("_ZL3Foov.constprop.80", tmp, sizeof(tmp)));
-  EXPECT_STREQ("Foo()", tmp);
-  EXPECT_TRUE(Demangle("_ZL3Foov.isra.18", tmp, sizeof(tmp)));
-  EXPECT_STREQ("Foo()", tmp);
-  EXPECT_TRUE(Demangle("_ZL3Foov.isra.2.constprop.18", tmp, sizeof(tmp)));
-  EXPECT_STREQ("Foo()", tmp);
-  // Invalid (truncated), should not demangle.
-  EXPECT_FALSE(Demangle("_ZL3Foov.clo", tmp, sizeof(tmp)));
-  // Invalid (.clone. not followed by number), should not demangle.
-  EXPECT_FALSE(Demangle("_ZL3Foov.clone.", tmp, sizeof(tmp)));
-  // Invalid (.clone. followed by non-number), should not demangle.
-  EXPECT_FALSE(Demangle("_ZL3Foov.clone.foo", tmp, sizeof(tmp)));
-  // Invalid (.constprop. not followed by number), should not demangle.
-  EXPECT_FALSE(Demangle("_ZL3Foov.isra.2.constprop.", tmp, sizeof(tmp)));
-}
-
-// Tests that verify that Demangle footprint is within some limit.
-// They are not to be run under sanitizers as the sanitizers increase
-// stack consumption by about 4x.
-#if defined(ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION) && \
-    !defined(ABSL_HAVE_ADDRESS_SANITIZER) &&                   \
-    !defined(ABSL_HAVE_MEMORY_SANITIZER) &&                    \
-    !defined(ABSL_HAVE_THREAD_SANITIZER)
-
-static const char *g_mangled;
-static char g_demangle_buffer[4096];
-static char *g_demangle_result;
-
-static void DemangleSignalHandler(int signo) {
-  if (Demangle(g_mangled, g_demangle_buffer, sizeof(g_demangle_buffer))) {
-    g_demangle_result = g_demangle_buffer;
-  } else {
-    g_demangle_result = nullptr;
-  }
-}
-
-// Call Demangle and figure out the stack footprint of this call.
-static const char *DemangleStackConsumption(const char *mangled,
-                                            int *stack_consumed) {
-  g_mangled = mangled;
-  *stack_consumed = GetSignalHandlerStackConsumption(DemangleSignalHandler);
-  ABSL_RAW_LOG(INFO, "Stack consumption of Demangle: %d", *stack_consumed);
-  return g_demangle_result;
-}
-
-// Demangle stack consumption should be within 8kB for simple mangled names
-// with some level of nesting. With alternate signal stack we have 64K,
-// but some signal handlers run on thread stack, and could have arbitrarily
-// little space left (so we don't want to make this number too large).
-const int kStackConsumptionUpperLimit = 8192;
-
-// Returns a mangled name nested to the given depth.
-static std::string NestedMangledName(int depth) {
-  std::string mangled_name = "_Z1a";
-  if (depth > 0) {
-    mangled_name += "IXL";
-    mangled_name += NestedMangledName(depth - 1);
-    mangled_name += "EEE";
-  }
-  return mangled_name;
-}
-
-TEST(Demangle, DemangleStackConsumption) {
-  // Measure stack consumption of Demangle for nested mangled names of varying
-  // depth.  Since Demangle is implemented as a recursive descent parser,
-  // stack consumption will grow as the nesting depth increases.  By measuring
-  // the stack consumption for increasing depths, we can see the growing
-  // impact of any stack-saving changes made to the code for Demangle.
-  int stack_consumed = 0;
-
-  const char *demangled =
-      DemangleStackConsumption("_Z6foobarv", &stack_consumed);
-  EXPECT_STREQ("foobar()", demangled);
-  EXPECT_GT(stack_consumed, 0);
-  EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit);
-
-  const std::string nested_mangled_name0 = NestedMangledName(0);
-  demangled = DemangleStackConsumption(nested_mangled_name0.c_str(),
-                                       &stack_consumed);
-  EXPECT_STREQ("a", demangled);
-  EXPECT_GT(stack_consumed, 0);
-  EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit);
-
-  const std::string nested_mangled_name1 = NestedMangledName(1);
-  demangled = DemangleStackConsumption(nested_mangled_name1.c_str(),
-                                       &stack_consumed);
-  EXPECT_STREQ("a<>", demangled);
-  EXPECT_GT(stack_consumed, 0);
-  EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit);
-
-  const std::string nested_mangled_name2 = NestedMangledName(2);
-  demangled = DemangleStackConsumption(nested_mangled_name2.c_str(),
-                                       &stack_consumed);
-  EXPECT_STREQ("a<>", demangled);
-  EXPECT_GT(stack_consumed, 0);
-  EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit);
-
-  const std::string nested_mangled_name3 = NestedMangledName(3);
-  demangled = DemangleStackConsumption(nested_mangled_name3.c_str(),
-                                       &stack_consumed);
-  EXPECT_STREQ("a<>", demangled);
-  EXPECT_GT(stack_consumed, 0);
-  EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit);
-}
-
-#endif  // Stack consumption tests
-
-static void TestOnInput(const char* input) {
-  static const int kOutSize = 1048576;
-  auto out = absl::make_unique<char[]>(kOutSize);
-  Demangle(input, out.get(), kOutSize);
-}
-
-TEST(DemangleRegression, NegativeLength) {
-  TestOnInput("_ZZn4");
-}
-
-TEST(DemangleRegression, DeeplyNestedArrayType) {
-  const int depth = 100000;
-  std::string data = "_ZStI";
-  data.reserve(data.size() + 3 * depth + 1);
-  for (int i = 0; i < depth; i++) {
-    data += "A1_";
-  }
-  TestOnInput(data.c_str());
-}
-
-}  // namespace
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
diff --git a/third_party/abseil_cpp/absl/debugging/internal/elf_mem_image.cc b/third_party/abseil_cpp/absl/debugging/internal/elf_mem_image.cc
deleted file mode 100644
index 24cc01302dc5..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/elf_mem_image.cc
+++ /dev/null
@@ -1,382 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Allow dynamic symbol lookup in an in-memory Elf image.
-//
-
-#include "absl/debugging/internal/elf_mem_image.h"
-
-#ifdef ABSL_HAVE_ELF_MEM_IMAGE  // defined in elf_mem_image.h
-
-#include <string.h>
-#include <cassert>
-#include <cstddef>
-#include "absl/base/internal/raw_logging.h"
-
-// From binutils/include/elf/common.h (this doesn't appear to be documented
-// anywhere else).
-//
-//   /* This flag appears in a Versym structure.  It means that the symbol
-//      is hidden, and is only visible with an explicit version number.
-//      This is a GNU extension.  */
-//   #define VERSYM_HIDDEN           0x8000
-//
-//   /* This is the mask for the rest of the Versym information.  */
-//   #define VERSYM_VERSION          0x7fff
-
-#define VERSYM_VERSION 0x7fff
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-namespace {
-
-#if __WORDSIZE == 32
-const int kElfClass = ELFCLASS32;
-int ElfBind(const ElfW(Sym) *symbol) { return ELF32_ST_BIND(symbol->st_info); }
-int ElfType(const ElfW(Sym) *symbol) { return ELF32_ST_TYPE(symbol->st_info); }
-#elif __WORDSIZE == 64
-const int kElfClass = ELFCLASS64;
-int ElfBind(const ElfW(Sym) *symbol) { return ELF64_ST_BIND(symbol->st_info); }
-int ElfType(const ElfW(Sym) *symbol) { return ELF64_ST_TYPE(symbol->st_info); }
-#else
-const int kElfClass = -1;
-int ElfBind(const ElfW(Sym) *) {
-  ABSL_RAW_LOG(FATAL, "Unexpected word size");
-  return 0;
-}
-int ElfType(const ElfW(Sym) *) {
-  ABSL_RAW_LOG(FATAL, "Unexpected word size");
-  return 0;
-}
-#endif
-
-// Extract an element from one of the ELF tables, cast it to desired type.
-// This is just a simple arithmetic and a glorified cast.
-// Callers are responsible for bounds checking.
-template <typename T>
-const T *GetTableElement(const ElfW(Ehdr) * ehdr, ElfW(Off) table_offset,
-                         ElfW(Word) element_size, size_t index) {
-  return reinterpret_cast<const T*>(reinterpret_cast<const char *>(ehdr)
-                                    + table_offset
-                                    + index * element_size);
-}
-
-}  // namespace
-
-// The value of this variable doesn't matter; it's used only for its
-// unique address.
-const int ElfMemImage::kInvalidBaseSentinel = 0;
-
-ElfMemImage::ElfMemImage(const void *base) {
-  ABSL_RAW_CHECK(base != kInvalidBase, "bad pointer");
-  Init(base);
-}
-
-int ElfMemImage::GetNumSymbols() const {
-  if (!hash_) {
-    return 0;
-  }
-  // See http://www.caldera.com/developers/gabi/latest/ch5.dynamic.html#hash
-  return hash_[1];
-}
-
-const ElfW(Sym) *ElfMemImage::GetDynsym(int index) const {
-  ABSL_RAW_CHECK(index < GetNumSymbols(), "index out of range");
-  return dynsym_ + index;
-}
-
-const ElfW(Versym) *ElfMemImage::GetVersym(int index) const {
-  ABSL_RAW_CHECK(index < GetNumSymbols(), "index out of range");
-  return versym_ + index;
-}
-
-const ElfW(Phdr) *ElfMemImage::GetPhdr(int index) const {
-  ABSL_RAW_CHECK(index < ehdr_->e_phnum, "index out of range");
-  return GetTableElement<ElfW(Phdr)>(ehdr_,
-                                     ehdr_->e_phoff,
-                                     ehdr_->e_phentsize,
-                                     index);
-}
-
-const char *ElfMemImage::GetDynstr(ElfW(Word) offset) const {
-  ABSL_RAW_CHECK(offset < strsize_, "offset out of range");
-  return dynstr_ + offset;
-}
-
-const void *ElfMemImage::GetSymAddr(const ElfW(Sym) *sym) const {
-  if (sym->st_shndx == SHN_UNDEF || sym->st_shndx >= SHN_LORESERVE) {
-    // Symbol corresponds to "special" (e.g. SHN_ABS) section.
-    return reinterpret_cast<const void *>(sym->st_value);
-  }
-  ABSL_RAW_CHECK(link_base_ < sym->st_value, "symbol out of range");
-  return GetTableElement<char>(ehdr_, 0, 1, sym->st_value - link_base_);
-}
-
-const ElfW(Verdef) *ElfMemImage::GetVerdef(int index) const {
-  ABSL_RAW_CHECK(0 <= index && static_cast<size_t>(index) <= verdefnum_,
-                 "index out of range");
-  const ElfW(Verdef) *version_definition = verdef_;
-  while (version_definition->vd_ndx < index && version_definition->vd_next) {
-    const char *const version_definition_as_char =
-        reinterpret_cast<const char *>(version_definition);
-    version_definition =
-        reinterpret_cast<const ElfW(Verdef) *>(version_definition_as_char +
-                                               version_definition->vd_next);
-  }
-  return version_definition->vd_ndx == index ? version_definition : nullptr;
-}
-
-const ElfW(Verdaux) *ElfMemImage::GetVerdefAux(
-    const ElfW(Verdef) *verdef) const {
-  return reinterpret_cast<const ElfW(Verdaux) *>(verdef+1);
-}
-
-const char *ElfMemImage::GetVerstr(ElfW(Word) offset) const {
-  ABSL_RAW_CHECK(offset < strsize_, "offset out of range");
-  return dynstr_ + offset;
-}
-
-void ElfMemImage::Init(const void *base) {
-  ehdr_      = nullptr;
-  dynsym_    = nullptr;
-  dynstr_    = nullptr;
-  versym_    = nullptr;
-  verdef_    = nullptr;
-  hash_      = nullptr;
-  strsize_   = 0;
-  verdefnum_ = 0;
-  link_base_ = ~0L;  // Sentinel: PT_LOAD .p_vaddr can't possibly be this.
-  if (!base) {
-    return;
-  }
-  const char *const base_as_char = reinterpret_cast<const char *>(base);
-  if (base_as_char[EI_MAG0] != ELFMAG0 || base_as_char[EI_MAG1] != ELFMAG1 ||
-      base_as_char[EI_MAG2] != ELFMAG2 || base_as_char[EI_MAG3] != ELFMAG3) {
-    assert(false);
-    return;
-  }
-  int elf_class = base_as_char[EI_CLASS];
-  if (elf_class != kElfClass) {
-    assert(false);
-    return;
-  }
-  switch (base_as_char[EI_DATA]) {
-    case ELFDATA2LSB: {
-      if (__LITTLE_ENDIAN != __BYTE_ORDER) {
-        assert(false);
-        return;
-      }
-      break;
-    }
-    case ELFDATA2MSB: {
-      if (__BIG_ENDIAN != __BYTE_ORDER) {
-        assert(false);
-        return;
-      }
-      break;
-    }
-    default: {
-      assert(false);
-      return;
-    }
-  }
-
-  ehdr_ = reinterpret_cast<const ElfW(Ehdr) *>(base);
-  const ElfW(Phdr) *dynamic_program_header = nullptr;
-  for (int i = 0; i < ehdr_->e_phnum; ++i) {
-    const ElfW(Phdr) *const program_header = GetPhdr(i);
-    switch (program_header->p_type) {
-      case PT_LOAD:
-        if (!~link_base_) {
-          link_base_ = program_header->p_vaddr;
-        }
-        break;
-      case PT_DYNAMIC:
-        dynamic_program_header = program_header;
-        break;
-    }
-  }
-  if (!~link_base_ || !dynamic_program_header) {
-    assert(false);
-    // Mark this image as not present. Can not recur infinitely.
-    Init(nullptr);
-    return;
-  }
-  ptrdiff_t relocation =
-      base_as_char - reinterpret_cast<const char *>(link_base_);
-  ElfW(Dyn) *dynamic_entry =
-      reinterpret_cast<ElfW(Dyn) *>(dynamic_program_header->p_vaddr +
-                                    relocation);
-  for (; dynamic_entry->d_tag != DT_NULL; ++dynamic_entry) {
-    const ElfW(Xword) value = dynamic_entry->d_un.d_val + relocation;
-    switch (dynamic_entry->d_tag) {
-      case DT_HASH:
-        hash_ = reinterpret_cast<ElfW(Word) *>(value);
-        break;
-      case DT_SYMTAB:
-        dynsym_ = reinterpret_cast<ElfW(Sym) *>(value);
-        break;
-      case DT_STRTAB:
-        dynstr_ = reinterpret_cast<const char *>(value);
-        break;
-      case DT_VERSYM:
-        versym_ = reinterpret_cast<ElfW(Versym) *>(value);
-        break;
-      case DT_VERDEF:
-        verdef_ = reinterpret_cast<ElfW(Verdef) *>(value);
-        break;
-      case DT_VERDEFNUM:
-        verdefnum_ = dynamic_entry->d_un.d_val;
-        break;
-      case DT_STRSZ:
-        strsize_ = dynamic_entry->d_un.d_val;
-        break;
-      default:
-        // Unrecognized entries explicitly ignored.
-        break;
-    }
-  }
-  if (!hash_ || !dynsym_ || !dynstr_ || !versym_ ||
-      !verdef_ || !verdefnum_ || !strsize_) {
-    assert(false);  // invalid VDSO
-    // Mark this image as not present. Can not recur infinitely.
-    Init(nullptr);
-    return;
-  }
-}
-
-bool ElfMemImage::LookupSymbol(const char *name,
-                               const char *version,
-                               int type,
-                               SymbolInfo *info_out) const {
-  for (const SymbolInfo& info : *this) {
-    if (strcmp(info.name, name) == 0 && strcmp(info.version, version) == 0 &&
-        ElfType(info.symbol) == type) {
-      if (info_out) {
-        *info_out = info;
-      }
-      return true;
-    }
-  }
-  return false;
-}
-
-bool ElfMemImage::LookupSymbolByAddress(const void *address,
-                                        SymbolInfo *info_out) const {
-  for (const SymbolInfo& info : *this) {
-    const char *const symbol_start =
-        reinterpret_cast<const char *>(info.address);
-    const char *const symbol_end = symbol_start + info.symbol->st_size;
-    if (symbol_start <= address && address < symbol_end) {
-      if (info_out) {
-        // Client wants to know details for that symbol (the usual case).
-        if (ElfBind(info.symbol) == STB_GLOBAL) {
-          // Strong symbol; just return it.
-          *info_out = info;
-          return true;
-        } else {
-          // Weak or local. Record it, but keep looking for a strong one.
-          *info_out = info;
-        }
-      } else {
-        // Client only cares if there is an overlapping symbol.
-        return true;
-      }
-    }
-  }
-  return false;
-}
-
-ElfMemImage::SymbolIterator::SymbolIterator(const void *const image, int index)
-    : index_(index), image_(image) {
-}
-
-const ElfMemImage::SymbolInfo *ElfMemImage::SymbolIterator::operator->() const {
-  return &info_;
-}
-
-const ElfMemImage::SymbolInfo& ElfMemImage::SymbolIterator::operator*() const {
-  return info_;
-}
-
-bool ElfMemImage::SymbolIterator::operator==(const SymbolIterator &rhs) const {
-  return this->image_ == rhs.image_ && this->index_ == rhs.index_;
-}
-
-bool ElfMemImage::SymbolIterator::operator!=(const SymbolIterator &rhs) const {
-  return !(*this == rhs);
-}
-
-ElfMemImage::SymbolIterator &ElfMemImage::SymbolIterator::operator++() {
-  this->Update(1);
-  return *this;
-}
-
-ElfMemImage::SymbolIterator ElfMemImage::begin() const {
-  SymbolIterator it(this, 0);
-  it.Update(0);
-  return it;
-}
-
-ElfMemImage::SymbolIterator ElfMemImage::end() const {
-  return SymbolIterator(this, GetNumSymbols());
-}
-
-void ElfMemImage::SymbolIterator::Update(int increment) {
-  const ElfMemImage *image = reinterpret_cast<const ElfMemImage *>(image_);
-  ABSL_RAW_CHECK(image->IsPresent() || increment == 0, "");
-  if (!image->IsPresent()) {
-    return;
-  }
-  index_ += increment;
-  if (index_ >= image->GetNumSymbols()) {
-    index_ = image->GetNumSymbols();
-    return;
-  }
-  const ElfW(Sym)    *symbol = image->GetDynsym(index_);
-  const ElfW(Versym) *version_symbol = image->GetVersym(index_);
-  ABSL_RAW_CHECK(symbol && version_symbol, "");
-  const char *const symbol_name = image->GetDynstr(symbol->st_name);
-  const ElfW(Versym) version_index = version_symbol[0] & VERSYM_VERSION;
-  const ElfW(Verdef) *version_definition = nullptr;
-  const char *version_name = "";
-  if (symbol->st_shndx == SHN_UNDEF) {
-    // Undefined symbols reference DT_VERNEED, not DT_VERDEF, and
-    // version_index could well be greater than verdefnum_, so calling
-    // GetVerdef(version_index) may trigger assertion.
-  } else {
-    version_definition = image->GetVerdef(version_index);
-  }
-  if (version_definition) {
-    // I am expecting 1 or 2 auxiliary entries: 1 for the version itself,
-    // optional 2nd if the version has a parent.
-    ABSL_RAW_CHECK(
-        version_definition->vd_cnt == 1 || version_definition->vd_cnt == 2,
-        "wrong number of entries");
-    const ElfW(Verdaux) *version_aux = image->GetVerdefAux(version_definition);
-    version_name = image->GetVerstr(version_aux->vda_name);
-  }
-  info_.name    = symbol_name;
-  info_.version = version_name;
-  info_.address = image->GetSymAddr(symbol);
-  info_.symbol  = symbol;
-}
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_HAVE_ELF_MEM_IMAGE
diff --git a/third_party/abseil_cpp/absl/debugging/internal/elf_mem_image.h b/third_party/abseil_cpp/absl/debugging/internal/elf_mem_image.h
deleted file mode 100644
index 46bfade3503e..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/elf_mem_image.h
+++ /dev/null
@@ -1,134 +0,0 @@
-/*
- * Copyright 2017 The Abseil Authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-// Allow dynamic symbol lookup for in-memory Elf images.
-
-#ifndef ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_
-#define ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_
-
-// Including this will define the __GLIBC__ macro if glibc is being
-// used.
-#include <climits>
-
-#include "absl/base/config.h"
-
-// Maybe one day we can rewrite this file not to require the elf
-// symbol extensions in glibc, but for right now we need them.
-#ifdef ABSL_HAVE_ELF_MEM_IMAGE
-#error ABSL_HAVE_ELF_MEM_IMAGE cannot be directly set
-#endif
-
-#if defined(__ELF__) && defined(__GLIBC__) && !defined(__native_client__) && \
-    !defined(__asmjs__) && !defined(__wasm__)
-#define ABSL_HAVE_ELF_MEM_IMAGE 1
-#endif
-
-#ifdef ABSL_HAVE_ELF_MEM_IMAGE
-
-#include <link.h>  // for ElfW
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-// An in-memory ELF image (may not exist on disk).
-class ElfMemImage {
- private:
-  // Sentinel: there could never be an elf image at &kInvalidBaseSentinel.
-  static const int kInvalidBaseSentinel;
-
- public:
-  // Sentinel: there could never be an elf image at this address.
-  static constexpr const void *const kInvalidBase =
-    static_cast<const void*>(&kInvalidBaseSentinel);
-
-  // Information about a single vdso symbol.
-  // All pointers are into .dynsym, .dynstr, or .text of the VDSO.
-  // Do not free() them or modify through them.
-  struct SymbolInfo {
-    const char      *name;      // E.g. "__vdso_getcpu"
-    const char      *version;   // E.g. "LINUX_2.6", could be ""
-                                // for unversioned symbol.
-    const void      *address;   // Relocated symbol address.
-    const ElfW(Sym) *symbol;    // Symbol in the dynamic symbol table.
-  };
-
-  // Supports iteration over all dynamic symbols.
-  class SymbolIterator {
-   public:
-    friend class ElfMemImage;
-    const SymbolInfo *operator->() const;
-    const SymbolInfo &operator*() const;
-    SymbolIterator& operator++();
-    bool operator!=(const SymbolIterator &rhs) const;
-    bool operator==(const SymbolIterator &rhs) const;
-   private:
-    SymbolIterator(const void *const image, int index);
-    void Update(int incr);
-    SymbolInfo info_;
-    int index_;
-    const void *const image_;
-  };
-
-
-  explicit ElfMemImage(const void *base);
-  void                 Init(const void *base);
-  bool                 IsPresent() const { return ehdr_ != nullptr; }
-  const ElfW(Phdr)*    GetPhdr(int index) const;
-  const ElfW(Sym)*     GetDynsym(int index) const;
-  const ElfW(Versym)*  GetVersym(int index) const;
-  const ElfW(Verdef)*  GetVerdef(int index) const;
-  const ElfW(Verdaux)* GetVerdefAux(const ElfW(Verdef) *verdef) const;
-  const char*          GetDynstr(ElfW(Word) offset) const;
-  const void*          GetSymAddr(const ElfW(Sym) *sym) const;
-  const char*          GetVerstr(ElfW(Word) offset) const;
-  int                  GetNumSymbols() const;
-
-  SymbolIterator begin() const;
-  SymbolIterator end() const;
-
-  // Look up versioned dynamic symbol in the image.
-  // Returns false if image is not present, or doesn't contain given
-  // symbol/version/type combination.
-  // If info_out is non-null, additional details are filled in.
-  bool LookupSymbol(const char *name, const char *version,
-                    int symbol_type, SymbolInfo *info_out) const;
-
-  // Find info about symbol (if any) which overlaps given address.
-  // Returns true if symbol was found; false if image isn't present
-  // or doesn't have a symbol overlapping given address.
-  // If info_out is non-null, additional details are filled in.
-  bool LookupSymbolByAddress(const void *address, SymbolInfo *info_out) const;
-
- private:
-  const ElfW(Ehdr) *ehdr_;
-  const ElfW(Sym) *dynsym_;
-  const ElfW(Versym) *versym_;
-  const ElfW(Verdef) *verdef_;
-  const ElfW(Word) *hash_;
-  const char *dynstr_;
-  size_t strsize_;
-  size_t verdefnum_;
-  ElfW(Addr) link_base_;     // Link-time base (p_vaddr of first PT_LOAD).
-};
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_HAVE_ELF_MEM_IMAGE
-
-#endif  // ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/examine_stack.cc b/third_party/abseil_cpp/absl/debugging/internal/examine_stack.cc
deleted file mode 100644
index 6e5ff1fbd836..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/examine_stack.cc
+++ /dev/null
@@ -1,187 +0,0 @@
-//
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-
-#include "absl/debugging/internal/examine_stack.h"
-
-#ifndef _WIN32
-#include <unistd.h>
-#endif
-
-#ifdef __APPLE__
-#include <sys/ucontext.h>
-#endif
-
-#include <csignal>
-#include <cstdio>
-
-#include "absl/base/attributes.h"
-#include "absl/base/internal/raw_logging.h"
-#include "absl/base/macros.h"
-#include "absl/debugging/stacktrace.h"
-#include "absl/debugging/symbolize.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-// Returns the program counter from signal context, nullptr if
-// unknown. vuc is a ucontext_t*. We use void* to avoid the use of
-// ucontext_t on non-POSIX systems.
-void* GetProgramCounter(void* vuc) {
-#ifdef __linux__
-  if (vuc != nullptr) {
-    ucontext_t* context = reinterpret_cast<ucontext_t*>(vuc);
-#if defined(__aarch64__)
-    return reinterpret_cast<void*>(context->uc_mcontext.pc);
-#elif defined(__arm__)
-    return reinterpret_cast<void*>(context->uc_mcontext.arm_pc);
-#elif defined(__i386__)
-    if (14 < ABSL_ARRAYSIZE(context->uc_mcontext.gregs))
-      return reinterpret_cast<void*>(context->uc_mcontext.gregs[14]);
-#elif defined(__mips__)
-    return reinterpret_cast<void*>(context->uc_mcontext.pc);
-#elif defined(__powerpc64__)
-    return reinterpret_cast<void*>(context->uc_mcontext.gp_regs[32]);
-#elif defined(__powerpc__)
-    return reinterpret_cast<void*>(context->uc_mcontext.regs->nip);
-#elif defined(__riscv)
-    return reinterpret_cast<void*>(context->uc_mcontext.__gregs[REG_PC]);
-#elif defined(__s390__) && !defined(__s390x__)
-    return reinterpret_cast<void*>(context->uc_mcontext.psw.addr & 0x7fffffff);
-#elif defined(__s390__) && defined(__s390x__)
-    return reinterpret_cast<void*>(context->uc_mcontext.psw.addr);
-#elif defined(__x86_64__)
-    if (16 < ABSL_ARRAYSIZE(context->uc_mcontext.gregs))
-      return reinterpret_cast<void*>(context->uc_mcontext.gregs[16]);
-#else
-#error "Undefined Architecture."
-#endif
-  }
-#elif defined(__APPLE__)
-  if (vuc != nullptr) {
-    ucontext_t* signal_ucontext = reinterpret_cast<ucontext_t*>(vuc);
-#if defined(__aarch64__)
-    return reinterpret_cast<void*>(
-        __darwin_arm_thread_state64_get_pc(signal_ucontext->uc_mcontext->__ss));
-#elif defined(__arm__)
-#if __DARWIN_UNIX03
-    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__pc);
-#else
-    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.pc);
-#endif
-#elif defined(__i386__)
-#if __DARWIN_UNIX03
-    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__eip);
-#else
-    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.eip);
-#endif
-#elif defined(__x86_64__)
-#if __DARWIN_UNIX03
-    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__rip);
-#else
-    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.rip);
-#endif
-#endif
-  }
-#elif defined(__akaros__)
-  auto* ctx = reinterpret_cast<struct user_context*>(vuc);
-  return reinterpret_cast<void*>(get_user_ctx_pc(ctx));
-#endif
-  static_cast<void>(vuc);
-  return nullptr;
-}
-
-// The %p field width for printf() functions is two characters per byte,
-// and two extra for the leading "0x".
-static constexpr int kPrintfPointerFieldWidth = 2 + 2 * sizeof(void*);
-
-// Print a program counter, its stack frame size, and its symbol name.
-// Note that there is a separate symbolize_pc argument. Return addresses may be
-// at the end of the function, and this allows the caller to back up from pc if
-// appropriate.
-static void DumpPCAndFrameSizeAndSymbol(void (*writerfn)(const char*, void*),
-                                        void* writerfn_arg, void* pc,
-                                        void* symbolize_pc, int framesize,
-                                        const char* const prefix) {
-  char tmp[1024];
-  const char* symbol = "(unknown)";
-  if (absl::Symbolize(symbolize_pc, tmp, sizeof(tmp))) {
-    symbol = tmp;
-  }
-  char buf[1024];
-  if (framesize <= 0) {
-    snprintf(buf, sizeof(buf), "%s@ %*p  (unknown)  %s\n", prefix,
-             kPrintfPointerFieldWidth, pc, symbol);
-  } else {
-    snprintf(buf, sizeof(buf), "%s@ %*p  %9d  %s\n", prefix,
-             kPrintfPointerFieldWidth, pc, framesize, symbol);
-  }
-  writerfn(buf, writerfn_arg);
-}
-
-// Print a program counter and the corresponding stack frame size.
-static void DumpPCAndFrameSize(void (*writerfn)(const char*, void*),
-                               void* writerfn_arg, void* pc, int framesize,
-                               const char* const prefix) {
-  char buf[100];
-  if (framesize <= 0) {
-    snprintf(buf, sizeof(buf), "%s@ %*p  (unknown)\n", prefix,
-             kPrintfPointerFieldWidth, pc);
-  } else {
-    snprintf(buf, sizeof(buf), "%s@ %*p  %9d\n", prefix,
-             kPrintfPointerFieldWidth, pc, framesize);
-  }
-  writerfn(buf, writerfn_arg);
-}
-
-void DumpPCAndFrameSizesAndStackTrace(
-    void* pc, void* const stack[], int frame_sizes[], int depth,
-    int min_dropped_frames, bool symbolize_stacktrace,
-    void (*writerfn)(const char*, void*), void* writerfn_arg) {
-  if (pc != nullptr) {
-    // We don't know the stack frame size for PC, use 0.
-    if (symbolize_stacktrace) {
-      DumpPCAndFrameSizeAndSymbol(writerfn, writerfn_arg, pc, pc, 0, "PC: ");
-    } else {
-      DumpPCAndFrameSize(writerfn, writerfn_arg, pc, 0, "PC: ");
-    }
-  }
-  for (int i = 0; i < depth; i++) {
-    if (symbolize_stacktrace) {
-      // Pass the previous address of pc as the symbol address because pc is a
-      // return address, and an overrun may occur when the function ends with a
-      // call to a function annotated noreturn (e.g. CHECK). Note that we don't
-      // do this for pc above, as the adjustment is only correct for return
-      // addresses.
-      DumpPCAndFrameSizeAndSymbol(writerfn, writerfn_arg, stack[i],
-                                  reinterpret_cast<char*>(stack[i]) - 1,
-                                  frame_sizes[i], "    ");
-    } else {
-      DumpPCAndFrameSize(writerfn, writerfn_arg, stack[i], frame_sizes[i],
-                         "    ");
-    }
-  }
-  if (min_dropped_frames > 0) {
-    char buf[100];
-    snprintf(buf, sizeof(buf), "    @ ... and at least %d more frames\n",
-             min_dropped_frames);
-    writerfn(buf, writerfn_arg);
-  }
-}
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
diff --git a/third_party/abseil_cpp/absl/debugging/internal/examine_stack.h b/third_party/abseil_cpp/absl/debugging/internal/examine_stack.h
deleted file mode 100644
index 393369131f1e..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/examine_stack.h
+++ /dev/null
@@ -1,42 +0,0 @@
-//
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-
-#ifndef ABSL_DEBUGGING_INTERNAL_EXAMINE_STACK_H_
-#define ABSL_DEBUGGING_INTERNAL_EXAMINE_STACK_H_
-
-#include "absl/base/config.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-// Returns the program counter from signal context, or nullptr if
-// unknown. `vuc` is a ucontext_t*. We use void* to avoid the use of
-// ucontext_t on non-POSIX systems.
-void* GetProgramCounter(void* vuc);
-
-// Uses `writerfn` to dump the program counter, stack trace, and stack
-// frame sizes.
-void DumpPCAndFrameSizesAndStackTrace(
-    void* pc, void* const stack[], int frame_sizes[], int depth,
-    int min_dropped_frames, bool symbolize_stacktrace,
-    void (*writerfn)(const char*, void*), void* writerfn_arg);
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_DEBUGGING_INTERNAL_EXAMINE_STACK_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/stack_consumption.cc b/third_party/abseil_cpp/absl/debugging/internal/stack_consumption.cc
deleted file mode 100644
index e3dd51c355ad..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/stack_consumption.cc
+++ /dev/null
@@ -1,185 +0,0 @@
-//
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#include "absl/debugging/internal/stack_consumption.h"
-
-#ifdef ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION
-
-#include <signal.h>
-#include <sys/mman.h>
-#include <unistd.h>
-
-#include <string.h>
-
-#include "absl/base/attributes.h"
-#include "absl/base/internal/raw_logging.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-namespace {
-
-// This code requires that we know the direction in which the stack
-// grows. It is commonly believed that this can be detected by putting
-// a variable on the stack and then passing its address to a function
-// that compares the address of this variable to the address of a
-// variable on the function's own stack. However, this is unspecified
-// behavior in C++: If two pointers p and q of the same type point to
-// different objects that are not members of the same object or
-// elements of the same array or to different functions, or if only
-// one of them is null, the results of p<q, p>q, p<=q, and p>=q are
-// unspecified. Therefore, instead we hardcode the direction of the
-// stack on platforms we know about.
-#if defined(__i386__) || defined(__x86_64__) || defined(__ppc__) || \
-    defined(__aarch64__)
-constexpr bool kStackGrowsDown = true;
-#else
-#error Need to define kStackGrowsDown
-#endif
-
-// To measure the stack footprint of some code, we create a signal handler
-// (for SIGUSR2 say) that exercises this code on an alternate stack. This
-// alternate stack is initialized to some known pattern (0x55, 0x55, 0x55,
-// ...). We then self-send this signal, and after the signal handler returns,
-// look at the alternate stack buffer to see what portion has been touched.
-//
-// This trick gives us the the stack footprint of the signal handler.  But the
-// signal handler, even before the code for it is exercised, consumes some
-// stack already. We however only want the stack usage of the code inside the
-// signal handler. To measure this accurately, we install two signal handlers:
-// one that does nothing and just returns, and the user-provided signal
-// handler. The difference between the stack consumption of these two signals
-// handlers should give us the stack foorprint of interest.
-
-void EmptySignalHandler(int) {}
-
-// This is arbitrary value, and could be increase further, at the cost of
-// memset()ting it all to known sentinel value.
-constexpr int kAlternateStackSize = 64 << 10;  // 64KiB
-
-constexpr int kSafetyMargin = 32;
-constexpr char kAlternateStackFillValue = 0x55;
-
-// These helper functions look at the alternate stack buffer, and figure
-// out what portion of this buffer has been touched - this is the stack
-// consumption of the signal handler running on this alternate stack.
-// This function will return -1 if the alternate stack buffer has not been
-// touched. It will abort the program if the buffer has overflowed or is about
-// to overflow.
-int GetStackConsumption(const void* const altstack) {
-  const char* begin;
-  int increment;
-  if (kStackGrowsDown) {
-    begin = reinterpret_cast<const char*>(altstack);
-    increment = 1;
-  } else {
-    begin = reinterpret_cast<const char*>(altstack) + kAlternateStackSize - 1;
-    increment = -1;
-  }
-
-  for (int usage_count = kAlternateStackSize; usage_count > 0; --usage_count) {
-    if (*begin != kAlternateStackFillValue) {
-      ABSL_RAW_CHECK(usage_count <= kAlternateStackSize - kSafetyMargin,
-                     "Buffer has overflowed or is about to overflow");
-      return usage_count;
-    }
-    begin += increment;
-  }
-
-  ABSL_RAW_LOG(FATAL, "Unreachable code");
-  return -1;
-}
-
-}  // namespace
-
-int GetSignalHandlerStackConsumption(void (*signal_handler)(int)) {
-  // The alt-signal-stack cannot be heap allocated because there is a
-  // bug in glibc-2.2 where some signal handler setup code looks at the
-  // current stack pointer to figure out what thread is currently running.
-  // Therefore, the alternate stack must be allocated from the main stack
-  // itself.
-  void* altstack = mmap(nullptr, kAlternateStackSize, PROT_READ | PROT_WRITE,
-                        MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-  ABSL_RAW_CHECK(altstack != MAP_FAILED, "mmap() failed");
-
-  // Set up the alt-signal-stack (and save the older one).
-  stack_t sigstk;
-  memset(&sigstk, 0, sizeof(sigstk));
-  sigstk.ss_sp = altstack;
-  sigstk.ss_size = kAlternateStackSize;
-  sigstk.ss_flags = 0;
-  stack_t old_sigstk;
-  memset(&old_sigstk, 0, sizeof(old_sigstk));
-  ABSL_RAW_CHECK(sigaltstack(&sigstk, &old_sigstk) == 0,
-                 "sigaltstack() failed");
-
-  // Set up SIGUSR1 and SIGUSR2 signal handlers (and save the older ones).
-  struct sigaction sa;
-  memset(&sa, 0, sizeof(sa));
-  struct sigaction old_sa1, old_sa2;
-  sigemptyset(&sa.sa_mask);
-  sa.sa_flags = SA_ONSTACK;
-
-  // SIGUSR1 maps to EmptySignalHandler.
-  sa.sa_handler = EmptySignalHandler;
-  ABSL_RAW_CHECK(sigaction(SIGUSR1, &sa, &old_sa1) == 0, "sigaction() failed");
-
-  // SIGUSR2 maps to signal_handler.
-  sa.sa_handler = signal_handler;
-  ABSL_RAW_CHECK(sigaction(SIGUSR2, &sa, &old_sa2) == 0, "sigaction() failed");
-
-  // Send SIGUSR1 signal and measure the stack consumption of the empty
-  // signal handler.
-  // The first signal might use more stack space. Run once and ignore the
-  // results to get that out of the way.
-  ABSL_RAW_CHECK(kill(getpid(), SIGUSR1) == 0, "kill() failed");
-
-  memset(altstack, kAlternateStackFillValue, kAlternateStackSize);
-  ABSL_RAW_CHECK(kill(getpid(), SIGUSR1) == 0, "kill() failed");
-  int base_stack_consumption = GetStackConsumption(altstack);
-
-  // Send SIGUSR2 signal and measure the stack consumption of signal_handler.
-  ABSL_RAW_CHECK(kill(getpid(), SIGUSR2) == 0, "kill() failed");
-  int signal_handler_stack_consumption = GetStackConsumption(altstack);
-
-  // Now restore the old alt-signal-stack and signal handlers.
-  if (old_sigstk.ss_sp == nullptr && old_sigstk.ss_size == 0 &&
-      (old_sigstk.ss_flags & SS_DISABLE)) {
-    // https://git.musl-libc.org/cgit/musl/commit/src/signal/sigaltstack.c?id=7829f42a2c8944555439380498ab8b924d0f2070
-    // The original stack has ss_size==0 and ss_flags==SS_DISABLE, but some
-    // versions of musl have a bug that rejects ss_size==0. Work around this by
-    // setting ss_size to MINSIGSTKSZ, which should be ignored by the kernel
-    // when SS_DISABLE is set.
-    old_sigstk.ss_size = MINSIGSTKSZ;
-  }
-  ABSL_RAW_CHECK(sigaltstack(&old_sigstk, nullptr) == 0,
-                 "sigaltstack() failed");
-  ABSL_RAW_CHECK(sigaction(SIGUSR1, &old_sa1, nullptr) == 0,
-                 "sigaction() failed");
-  ABSL_RAW_CHECK(sigaction(SIGUSR2, &old_sa2, nullptr) == 0,
-                 "sigaction() failed");
-
-  ABSL_RAW_CHECK(munmap(altstack, kAlternateStackSize) == 0, "munmap() failed");
-  if (signal_handler_stack_consumption != -1 && base_stack_consumption != -1) {
-    return signal_handler_stack_consumption - base_stack_consumption;
-  }
-  return -1;
-}
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION
diff --git a/third_party/abseil_cpp/absl/debugging/internal/stack_consumption.h b/third_party/abseil_cpp/absl/debugging/internal/stack_consumption.h
deleted file mode 100644
index 2b5e7151667c..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/stack_consumption.h
+++ /dev/null
@@ -1,50 +0,0 @@
-//
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Helper function for measuring stack consumption of signal handlers.
-
-#ifndef ABSL_DEBUGGING_INTERNAL_STACK_CONSUMPTION_H_
-#define ABSL_DEBUGGING_INTERNAL_STACK_CONSUMPTION_H_
-
-#include "absl/base/config.h"
-
-// The code in this module is not portable.
-// Use this feature test macro to detect its availability.
-#ifdef ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION
-#error ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION cannot be set directly
-#elif !defined(__APPLE__) && !defined(_WIN32) &&                     \
-    (defined(__i386__) || defined(__x86_64__) || defined(__ppc__) || \
-     defined(__aarch64__))
-#define ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION 1
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-// Returns the stack consumption in bytes for the code exercised by
-// signal_handler.  To measure stack consumption, signal_handler is registered
-// as a signal handler, so the code that it exercises must be async-signal
-// safe.  The argument of signal_handler is an implementation detail of signal
-// handlers and should ignored by the code for signal_handler.  Use global
-// variables to pass information between your test code and signal_handler.
-int GetSignalHandlerStackConsumption(void (*signal_handler)(int));
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION
-
-#endif  // ABSL_DEBUGGING_INTERNAL_STACK_CONSUMPTION_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/stack_consumption_test.cc b/third_party/abseil_cpp/absl/debugging/internal/stack_consumption_test.cc
deleted file mode 100644
index 80445bf43aab..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/stack_consumption_test.cc
+++ /dev/null
@@ -1,50 +0,0 @@
-//
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#include "absl/debugging/internal/stack_consumption.h"
-
-#ifdef ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION
-
-#include <string.h>
-
-#include "gtest/gtest.h"
-#include "absl/base/internal/raw_logging.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-namespace {
-
-static void SimpleSignalHandler(int signo) {
-  char buf[100];
-  memset(buf, 'a', sizeof(buf));
-
-  // Never true, but prevents compiler from optimizing buf out.
-  if (signo == 0) {
-    ABSL_RAW_LOG(INFO, "%p", static_cast<void*>(buf));
-  }
-}
-
-TEST(SignalHandlerStackConsumptionTest, MeasuresStackConsumption) {
-  // Our handler should consume reasonable number of bytes.
-  EXPECT_GE(GetSignalHandlerStackConsumption(SimpleSignalHandler), 100);
-}
-
-}  // namespace
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION
diff --git a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc b/third_party/abseil_cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc
deleted file mode 100644
index f4859d7c210a..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc
+++ /dev/null
@@ -1,199 +0,0 @@
-#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_AARCH64_INL_H_
-#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_AARCH64_INL_H_
-
-// Generate stack tracer for aarch64
-
-#if defined(__linux__)
-#include <sys/mman.h>
-#include <ucontext.h>
-#include <unistd.h>
-#endif
-
-#include <atomic>
-#include <cassert>
-#include <cstdint>
-#include <iostream>
-
-#include "absl/base/attributes.h"
-#include "absl/debugging/internal/address_is_readable.h"
-#include "absl/debugging/internal/vdso_support.h"  // a no-op on non-elf or non-glibc systems
-#include "absl/debugging/stacktrace.h"
-
-static const uintptr_t kUnknownFrameSize = 0;
-
-#if defined(__linux__)
-// Returns the address of the VDSO __kernel_rt_sigreturn function, if present.
-static const unsigned char* GetKernelRtSigreturnAddress() {
-  constexpr uintptr_t kImpossibleAddress = 1;
-  ABSL_CONST_INIT static std::atomic<uintptr_t> memoized{kImpossibleAddress};
-  uintptr_t address = memoized.load(std::memory_order_relaxed);
-  if (address != kImpossibleAddress) {
-    return reinterpret_cast<const unsigned char*>(address);
-  }
-
-  address = reinterpret_cast<uintptr_t>(nullptr);
-
-#ifdef ABSL_HAVE_VDSO_SUPPORT
-  absl::debugging_internal::VDSOSupport vdso;
-  if (vdso.IsPresent()) {
-    absl::debugging_internal::VDSOSupport::SymbolInfo symbol_info;
-    auto lookup = [&](int type) {
-      return vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_2.6.39", type,
-                               &symbol_info);
-    };
-    if ((!lookup(STT_FUNC) && !lookup(STT_NOTYPE)) ||
-        symbol_info.address == nullptr) {
-      // Unexpected: VDSO is present, yet the expected symbol is missing
-      // or null.
-      assert(false && "VDSO is present, but doesn't have expected symbol");
-    } else {
-      if (reinterpret_cast<uintptr_t>(symbol_info.address) !=
-          kImpossibleAddress) {
-        address = reinterpret_cast<uintptr_t>(symbol_info.address);
-      } else {
-        assert(false && "VDSO returned invalid address");
-      }
-    }
-  }
-#endif
-
-  memoized.store(address, std::memory_order_relaxed);
-  return reinterpret_cast<const unsigned char*>(address);
-}
-#endif  // __linux__
-
-// Compute the size of a stack frame in [low..high).  We assume that
-// low < high.  Return size of kUnknownFrameSize.
-template<typename T>
-static inline uintptr_t ComputeStackFrameSize(const T* low,
-                                              const T* high) {
-  const char* low_char_ptr = reinterpret_cast<const char *>(low);
-  const char* high_char_ptr = reinterpret_cast<const char *>(high);
-  return low < high ? high_char_ptr - low_char_ptr : kUnknownFrameSize;
-}
-
-// Given a pointer to a stack frame, locate and return the calling
-// stackframe, or return null if no stackframe can be found. Perform sanity
-// checks (the strictness of which is controlled by the boolean parameter
-// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
-template<bool STRICT_UNWINDING, bool WITH_CONTEXT>
-ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS  // May read random elements from stack.
-ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY   // May read random elements from stack.
-static void **NextStackFrame(void **old_frame_pointer, const void *uc) {
-  void **new_frame_pointer = reinterpret_cast<void**>(*old_frame_pointer);
-  bool check_frame_size = true;
-
-#if defined(__linux__)
-  if (WITH_CONTEXT && uc != nullptr) {
-    // Check to see if next frame's return address is __kernel_rt_sigreturn.
-    if (old_frame_pointer[1] == GetKernelRtSigreturnAddress()) {
-      const ucontext_t *ucv = static_cast<const ucontext_t *>(uc);
-      // old_frame_pointer[0] is not suitable for unwinding, look at
-      // ucontext to discover frame pointer before signal.
-      void **const pre_signal_frame_pointer =
-          reinterpret_cast<void **>(ucv->uc_mcontext.regs[29]);
-
-      // Check that alleged frame pointer is actually readable. This is to
-      // prevent "double fault" in case we hit the first fault due to e.g.
-      // stack corruption.
-      if (!absl::debugging_internal::AddressIsReadable(
-              pre_signal_frame_pointer))
-        return nullptr;
-
-      // Alleged frame pointer is readable, use it for further unwinding.
-      new_frame_pointer = pre_signal_frame_pointer;
-
-      // Skip frame size check if we return from a signal. We may be using a
-      // an alternate stack for signals.
-      check_frame_size = false;
-    }
-  }
-#endif
-
-  // aarch64 ABI requires stack pointer to be 16-byte-aligned.
-  if ((reinterpret_cast<uintptr_t>(new_frame_pointer) & 15) != 0)
-    return nullptr;
-
-  // Check frame size.  In strict mode, we assume frames to be under
-  // 100,000 bytes.  In non-strict mode, we relax the limit to 1MB.
-  if (check_frame_size) {
-    const uintptr_t max_size = STRICT_UNWINDING ? 100000 : 1000000;
-    const uintptr_t frame_size =
-        ComputeStackFrameSize(old_frame_pointer, new_frame_pointer);
-    if (frame_size == kUnknownFrameSize || frame_size > max_size)
-      return nullptr;
-  }
-
-  return new_frame_pointer;
-}
-
-template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
-ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS  // May read random elements from stack.
-ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY   // May read random elements from stack.
-static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
-                      const void *ucp, int *min_dropped_frames) {
-#ifdef __GNUC__
-  void **frame_pointer = reinterpret_cast<void**>(__builtin_frame_address(0));
-#else
-# error reading stack point not yet supported on this platform.
-#endif
-
-  skip_count++;    // Skip the frame for this function.
-  int n = 0;
-
-  // The frame pointer points to low address of a frame.  The first 64-bit
-  // word of a frame points to the next frame up the call chain, which normally
-  // is just after the high address of the current frame.  The second word of
-  // a frame contains return adress of to the caller.   To find a pc value
-  // associated with the current frame, we need to go down a level in the call
-  // chain.  So we remember return the address of the last frame seen.  This
-  // does not work for the first stack frame, which belongs to UnwindImp() but
-  // we skip the frame for UnwindImp() anyway.
-  void* prev_return_address = nullptr;
-
-  while (frame_pointer && n < max_depth) {
-    // The absl::GetStackFrames routine is called when we are in some
-    // informational context (the failure signal handler for example).
-    // Use the non-strict unwinding rules to produce a stack trace
-    // that is as complete as possible (even if it contains a few bogus
-    // entries in some rare cases).
-    void **next_frame_pointer =
-        NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
-
-    if (skip_count > 0) {
-      skip_count--;
-    } else {
-      result[n] = prev_return_address;
-      if (IS_STACK_FRAMES) {
-        sizes[n] = ComputeStackFrameSize(frame_pointer, next_frame_pointer);
-      }
-      n++;
-    }
-    prev_return_address = frame_pointer[1];
-    frame_pointer = next_frame_pointer;
-  }
-  if (min_dropped_frames != nullptr) {
-    // Implementation detail: we clamp the max of frames we are willing to
-    // count, so as not to spend too much time in the loop below.
-    const int kMaxUnwind = 200;
-    int j = 0;
-    for (; frame_pointer != nullptr && j < kMaxUnwind; j++) {
-      frame_pointer =
-          NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
-    }
-    *min_dropped_frames = j;
-  }
-  return n;
-}
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-bool StackTraceWorksForTest() {
-  return true;
-}
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_AARCH64_INL_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_arm-inl.inc b/third_party/abseil_cpp/absl/debugging/internal/stacktrace_arm-inl.inc
deleted file mode 100644
index 2a1bf2e88694..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_arm-inl.inc
+++ /dev/null
@@ -1,134 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-// This is inspired by Craig Silverstein's PowerPC stacktrace code.
-
-#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_ARM_INL_H_
-#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_ARM_INL_H_
-
-#include <cstdint>
-
-#include "absl/debugging/stacktrace.h"
-
-// WARNING:
-// This only works if all your code is in either ARM or THUMB mode.  With
-// interworking, the frame pointer of the caller can either be in r11 (ARM
-// mode) or r7 (THUMB mode).  A callee only saves the frame pointer of its
-// mode in a fixed location on its stack frame.  If the caller is a different
-// mode, there is no easy way to find the frame pointer.  It can either be
-// still in the designated register or saved on stack along with other callee
-// saved registers.
-
-// Given a pointer to a stack frame, locate and return the calling
-// stackframe, or return nullptr if no stackframe can be found. Perform sanity
-// checks (the strictness of which is controlled by the boolean parameter
-// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
-template<bool STRICT_UNWINDING>
-static void **NextStackFrame(void **old_sp) {
-  void **new_sp = (void**) old_sp[-1];
-
-  // Check that the transition from frame pointer old_sp to frame
-  // pointer new_sp isn't clearly bogus
-  if (STRICT_UNWINDING) {
-    // With the stack growing downwards, older stack frame must be
-    // at a greater address that the current one.
-    if (new_sp <= old_sp) return nullptr;
-    // Assume stack frames larger than 100,000 bytes are bogus.
-    if ((uintptr_t)new_sp - (uintptr_t)old_sp > 100000) return nullptr;
-  } else {
-    // In the non-strict mode, allow discontiguous stack frames.
-    // (alternate-signal-stacks for example).
-    if (new_sp == old_sp) return nullptr;
-    // And allow frames upto about 1MB.
-    if ((new_sp > old_sp)
-        && ((uintptr_t)new_sp - (uintptr_t)old_sp > 1000000)) return nullptr;
-  }
-  if ((uintptr_t)new_sp & (sizeof(void *) - 1)) return nullptr;
-  return new_sp;
-}
-
-// This ensures that absl::GetStackTrace sets up the Link Register properly.
-#ifdef __GNUC__
-void StacktraceArmDummyFunction() __attribute__((noinline));
-void StacktraceArmDummyFunction() { __asm__ volatile(""); }
-#else
-# error StacktraceArmDummyFunction() needs to be ported to this platform.
-#endif
-
-template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
-static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
-                      const void * /* ucp */, int *min_dropped_frames) {
-#ifdef __GNUC__
-  void **sp = reinterpret_cast<void**>(__builtin_frame_address(0));
-#else
-# error reading stack point not yet supported on this platform.
-#endif
-
-  // On ARM, the return address is stored in the link register (r14).
-  // This is not saved on the stack frame of a leaf function.  To
-  // simplify code that reads return addresses, we call a dummy
-  // function so that the return address of this function is also
-  // stored in the stack frame.  This works at least for gcc.
-  StacktraceArmDummyFunction();
-
-  int n = 0;
-  while (sp && n < max_depth) {
-    // The absl::GetStackFrames routine is called when we are in some
-    // informational context (the failure signal handler for example).
-    // Use the non-strict unwinding rules to produce a stack trace
-    // that is as complete as possible (even if it contains a few bogus
-    // entries in some rare cases).
-    void **next_sp = NextStackFrame<!IS_STACK_FRAMES>(sp);
-
-    if (skip_count > 0) {
-      skip_count--;
-    } else {
-      result[n] = *sp;
-
-      if (IS_STACK_FRAMES) {
-        if (next_sp > sp) {
-          sizes[n] = (uintptr_t)next_sp - (uintptr_t)sp;
-        } else {
-          // A frame-size of 0 is used to indicate unknown frame size.
-          sizes[n] = 0;
-        }
-      }
-      n++;
-    }
-    sp = next_sp;
-  }
-  if (min_dropped_frames != nullptr) {
-    // Implementation detail: we clamp the max of frames we are willing to
-    // count, so as not to spend too much time in the loop below.
-    const int kMaxUnwind = 200;
-    int j = 0;
-    for (; sp != nullptr && j < kMaxUnwind; j++) {
-      sp = NextStackFrame<!IS_STACK_FRAMES>(sp);
-    }
-    *min_dropped_frames = j;
-  }
-  return n;
-}
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-bool StackTraceWorksForTest() {
-  return false;
-}
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_ARM_INL_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_config.h b/third_party/abseil_cpp/absl/debugging/internal/stacktrace_config.h
deleted file mode 100644
index 90af852818e7..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_config.h
+++ /dev/null
@@ -1,89 +0,0 @@
-/*
- * Copyright 2017 The Abseil Authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
-
- * Defines ABSL_STACKTRACE_INL_HEADER to the *-inl.h containing
- * actual unwinder implementation.
- * This header is "private" to stacktrace.cc.
- * DO NOT include it into any other files.
-*/
-#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_CONFIG_H_
-#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_CONFIG_H_
-
-#if defined(ABSL_STACKTRACE_INL_HEADER)
-#error ABSL_STACKTRACE_INL_HEADER cannot be directly set
-
-#elif defined(_WIN32)
-#define ABSL_STACKTRACE_INL_HEADER \
-    "absl/debugging/internal/stacktrace_win32-inl.inc"
-
-#elif defined(__APPLE__)
-// Thread local support required for UnwindImpl.
-// Notes:
-// * Xcode's clang did not support `thread_local` until version 8, and
-//   even then not for all iOS < 9.0.
-// * Xcode 9.3 started disallowing `thread_local` for 32-bit iOS simulator
-//   targeting iOS 9.x.
-// * Xcode 10 moves the deployment target check for iOS < 9.0 to link time
-//   making __has_feature unreliable there.
-//
-// Otherwise, `__has_feature` is only supported by Clang so it has be inside
-// `defined(__APPLE__)` check.
-#if __has_feature(cxx_thread_local) && \
-    !(TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_9_0)
-#define ABSL_STACKTRACE_INL_HEADER \
-  "absl/debugging/internal/stacktrace_generic-inl.inc"
-#endif
-
-#elif defined(__linux__) && !defined(__ANDROID__)
-
-#if defined(NO_FRAME_POINTER) && \
-    (defined(__i386__) || defined(__x86_64__) || defined(__aarch64__))
-// Note: The libunwind-based implementation is not available to open-source
-// users.
-#define ABSL_STACKTRACE_INL_HEADER \
-  "absl/debugging/internal/stacktrace_libunwind-inl.inc"
-#define STACKTRACE_USES_LIBUNWIND 1
-#elif defined(NO_FRAME_POINTER) && defined(__has_include)
-#if __has_include(<execinfo.h>)
-// Note: When using glibc this may require -funwind-tables to function properly.
-#define ABSL_STACKTRACE_INL_HEADER \
-  "absl/debugging/internal/stacktrace_generic-inl.inc"
-#endif
-#elif defined(__i386__) || defined(__x86_64__)
-#define ABSL_STACKTRACE_INL_HEADER \
-  "absl/debugging/internal/stacktrace_x86-inl.inc"
-#elif defined(__ppc__) || defined(__PPC__)
-#define ABSL_STACKTRACE_INL_HEADER \
-  "absl/debugging/internal/stacktrace_powerpc-inl.inc"
-#elif defined(__aarch64__)
-#define ABSL_STACKTRACE_INL_HEADER \
-  "absl/debugging/internal/stacktrace_aarch64-inl.inc"
-#elif defined(__has_include)
-#if __has_include(<execinfo.h>)
-// Note: When using glibc this may require -funwind-tables to function properly.
-#define ABSL_STACKTRACE_INL_HEADER \
-  "absl/debugging/internal/stacktrace_generic-inl.inc"
-#endif
-#endif
-
-#endif
-
-// Fallback to the empty implementation.
-#if !defined(ABSL_STACKTRACE_INL_HEADER)
-#define ABSL_STACKTRACE_INL_HEADER \
-  "absl/debugging/internal/stacktrace_unimplemented-inl.inc"
-#endif
-
-#endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_CONFIG_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_generic-inl.inc b/third_party/abseil_cpp/absl/debugging/internal/stacktrace_generic-inl.inc
deleted file mode 100644
index b2792a1f3ada..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_generic-inl.inc
+++ /dev/null
@@ -1,108 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-// Portable implementation - just use glibc
-//
-// Note:  The glibc implementation may cause a call to malloc.
-// This can cause a deadlock in HeapProfiler.
-
-#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_GENERIC_INL_H_
-#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_GENERIC_INL_H_
-
-#include <execinfo.h>
-#include <atomic>
-#include <cstring>
-
-#include "absl/debugging/stacktrace.h"
-#include "absl/base/attributes.h"
-
-// Sometimes, we can try to get a stack trace from within a stack
-// trace, because we don't block signals inside this code (which would be too
-// expensive: the two extra system calls per stack trace do matter here).
-// That can cause a self-deadlock.
-// Protect against such reentrant call by failing to get a stack trace.
-//
-// We use __thread here because the code here is extremely low level -- it is
-// called while collecting stack traces from within malloc and mmap, and thus
-// can not call anything which might call malloc or mmap itself.
-static __thread int recursive = 0;
-
-// The stack trace function might be invoked very early in the program's
-// execution (e.g. from the very first malloc if using tcmalloc). Also, the
-// glibc implementation itself will trigger malloc the first time it is called.
-// As such, we suppress usage of backtrace during this early stage of execution.
-static std::atomic<bool> disable_stacktraces(true);  // Disabled until healthy.
-// Waiting until static initializers run seems to be late enough.
-// This file is included into stacktrace.cc so this will only run once.
-ABSL_ATTRIBUTE_UNUSED static int stacktraces_enabler = []() {
-  void* unused_stack[1];
-  // Force the first backtrace to happen early to get the one-time shared lib
-  // loading (allocation) out of the way. After the first call it is much safer
-  // to use backtrace from a signal handler if we crash somewhere later.
-  backtrace(unused_stack, 1);
-  disable_stacktraces.store(false, std::memory_order_relaxed);
-  return 0;
-}();
-
-template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
-static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
-                      const void *ucp, int *min_dropped_frames) {
-  if (recursive || disable_stacktraces.load(std::memory_order_relaxed)) {
-    return 0;
-  }
-  ++recursive;
-
-  static_cast<void>(ucp);  // Unused.
-  static const int kStackLength = 64;
-  void * stack[kStackLength];
-  int size;
-
-  size = backtrace(stack, kStackLength);
-  skip_count++;  // we want to skip the current frame as well
-  int result_count = size - skip_count;
-  if (result_count < 0)
-    result_count = 0;
-  if (result_count > max_depth)
-    result_count = max_depth;
-  for (int i = 0; i < result_count; i++)
-    result[i] = stack[i + skip_count];
-
-  if (IS_STACK_FRAMES) {
-    // No implementation for finding out the stack frame sizes yet.
-    memset(sizes, 0, sizeof(*sizes) * result_count);
-  }
-  if (min_dropped_frames != nullptr) {
-    if (size - skip_count - max_depth > 0) {
-      *min_dropped_frames = size - skip_count - max_depth;
-    } else {
-      *min_dropped_frames = 0;
-    }
-  }
-
-  --recursive;
-
-  return result_count;
-}
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-bool StackTraceWorksForTest() {
-  return true;
-}
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_GENERIC_INL_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_powerpc-inl.inc b/third_party/abseil_cpp/absl/debugging/internal/stacktrace_powerpc-inl.inc
deleted file mode 100644
index 2e7c2f404f20..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_powerpc-inl.inc
+++ /dev/null
@@ -1,248 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-// Produce stack trace.  I'm guessing (hoping!) the code is much like
-// for x86.  For apple machines, at least, it seems to be; see
-//    https://developer.apple.com/documentation/mac/runtimehtml/RTArch-59.html
-//    https://www.linux-foundation.org/spec/ELF/ppc64/PPC-elf64abi-1.9.html#STACK
-// Linux has similar code: http://patchwork.ozlabs.org/linuxppc/patch?id=8882
-
-#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_POWERPC_INL_H_
-#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_POWERPC_INL_H_
-
-#if defined(__linux__)
-#include <asm/ptrace.h>   // for PT_NIP.
-#include <ucontext.h>     // for ucontext_t
-#endif
-
-#include <unistd.h>
-#include <cassert>
-#include <cstdint>
-#include <cstdio>
-
-#include "absl/base/attributes.h"
-#include "absl/base/optimization.h"
-#include "absl/base/port.h"
-#include "absl/debugging/stacktrace.h"
-#include "absl/debugging/internal/address_is_readable.h"
-#include "absl/debugging/internal/vdso_support.h"  // a no-op on non-elf or non-glibc systems
-
-// Given a stack pointer, return the saved link register value.
-// Note that this is the link register for a callee.
-static inline void *StacktracePowerPCGetLR(void **sp) {
-  // PowerPC has 3 main ABIs, which say where in the stack the
-  // Link Register is.  For DARWIN and AIX (used by apple and
-  // linux ppc64), it's in sp[2].  For SYSV (used by linux ppc),
-  // it's in sp[1].
-#if defined(_CALL_AIX) || defined(_CALL_DARWIN)
-  return *(sp+2);
-#elif defined(_CALL_SYSV)
-  return *(sp+1);
-#elif defined(__APPLE__) || defined(__FreeBSD__) || \
-    (defined(__linux__) && defined(__PPC64__))
-  // This check is in case the compiler doesn't define _CALL_AIX/etc.
-  return *(sp+2);
-#elif defined(__linux)
-  // This check is in case the compiler doesn't define _CALL_SYSV.
-  return *(sp+1);
-#else
-#error Need to specify the PPC ABI for your archiecture.
-#endif
-}
-
-// Given a pointer to a stack frame, locate and return the calling
-// stackframe, or return null if no stackframe can be found. Perform sanity
-// checks (the strictness of which is controlled by the boolean parameter
-// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
-template<bool STRICT_UNWINDING, bool IS_WITH_CONTEXT>
-ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS  // May read random elements from stack.
-ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY   // May read random elements from stack.
-static void **NextStackFrame(void **old_sp, const void *uc) {
-  void **new_sp = (void **) *old_sp;
-  enum { kStackAlignment = 16 };
-
-  // Check that the transition from frame pointer old_sp to frame
-  // pointer new_sp isn't clearly bogus
-  if (STRICT_UNWINDING) {
-    // With the stack growing downwards, older stack frame must be
-    // at a greater address that the current one.
-    if (new_sp <= old_sp) return nullptr;
-    // Assume stack frames larger than 100,000 bytes are bogus.
-    if ((uintptr_t)new_sp - (uintptr_t)old_sp > 100000) return nullptr;
-  } else {
-    // In the non-strict mode, allow discontiguous stack frames.
-    // (alternate-signal-stacks for example).
-    if (new_sp == old_sp) return nullptr;
-    // And allow frames upto about 1MB.
-    if ((new_sp > old_sp)
-        && ((uintptr_t)new_sp - (uintptr_t)old_sp > 1000000)) return nullptr;
-  }
-  if ((uintptr_t)new_sp % kStackAlignment != 0) return nullptr;
-
-#if defined(__linux__)
-  enum StackTraceKernelSymbolStatus {
-      kNotInitialized = 0, kAddressValid, kAddressInvalid };
-
-  if (IS_WITH_CONTEXT && uc != nullptr) {
-    static StackTraceKernelSymbolStatus kernel_symbol_status =
-        kNotInitialized;  // Sentinel: not computed yet.
-    // Initialize with sentinel value: __kernel_rt_sigtramp_rt64 can not
-    // possibly be there.
-    static const unsigned char *kernel_sigtramp_rt64_address = nullptr;
-    if (kernel_symbol_status == kNotInitialized) {
-      absl::debugging_internal::VDSOSupport vdso;
-      if (vdso.IsPresent()) {
-        absl::debugging_internal::VDSOSupport::SymbolInfo
-            sigtramp_rt64_symbol_info;
-        if (!vdso.LookupSymbol(
-                "__kernel_sigtramp_rt64", "LINUX_2.6.15",
-                absl::debugging_internal::VDSOSupport::kVDSOSymbolType,
-                &sigtramp_rt64_symbol_info) ||
-            sigtramp_rt64_symbol_info.address == nullptr) {
-          // Unexpected: VDSO is present, yet the expected symbol is missing
-          // or null.
-          assert(false && "VDSO is present, but doesn't have expected symbol");
-          kernel_symbol_status = kAddressInvalid;
-        } else {
-          kernel_sigtramp_rt64_address =
-              reinterpret_cast<const unsigned char *>(
-                  sigtramp_rt64_symbol_info.address);
-          kernel_symbol_status = kAddressValid;
-        }
-      } else {
-        kernel_symbol_status = kAddressInvalid;
-      }
-    }
-
-    if (new_sp != nullptr &&
-        kernel_symbol_status == kAddressValid &&
-        StacktracePowerPCGetLR(new_sp) == kernel_sigtramp_rt64_address) {
-      const ucontext_t* signal_context =
-          reinterpret_cast<const ucontext_t*>(uc);
-      void **const sp_before_signal =
-          reinterpret_cast<void**>(signal_context->uc_mcontext.gp_regs[PT_R1]);
-      // Check that alleged sp before signal is nonnull and is reasonably
-      // aligned.
-      if (sp_before_signal != nullptr &&
-          ((uintptr_t)sp_before_signal % kStackAlignment) == 0) {
-        // Check that alleged stack pointer is actually readable. This is to
-        // prevent a "double fault" in case we hit the first fault due to e.g.
-        // a stack corruption.
-        if (absl::debugging_internal::AddressIsReadable(sp_before_signal)) {
-          // Alleged stack pointer is readable, use it for further unwinding.
-          new_sp = sp_before_signal;
-        }
-      }
-    }
-  }
-#endif
-
-  return new_sp;
-}
-
-// This ensures that absl::GetStackTrace sets up the Link Register properly.
-ABSL_ATTRIBUTE_NOINLINE static void AbslStacktracePowerPCDummyFunction() {
-  ABSL_BLOCK_TAIL_CALL_OPTIMIZATION();
-}
-
-template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
-ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS  // May read random elements from stack.
-ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY   // May read random elements from stack.
-static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
-                      const void *ucp, int *min_dropped_frames) {
-  void **sp;
-  // Apple macOS uses an old version of gnu as -- both Darwin 7.9.0 (Panther)
-  // and Darwin 8.8.1 (Tiger) use as 1.38.  This means we have to use a
-  // different asm syntax.  I don't know quite the best way to discriminate
-  // systems using the old as from the new one; I've gone with __APPLE__.
-#ifdef __APPLE__
-  __asm__ volatile ("mr %0,r1" : "=r" (sp));
-#else
-  __asm__ volatile ("mr %0,1" : "=r" (sp));
-#endif
-
-  // On PowerPC, the "Link Register" or "Link Record" (LR), is a stack
-  // entry that holds the return address of the subroutine call (what
-  // instruction we run after our function finishes).  This is the
-  // same as the stack-pointer of our parent routine, which is what we
-  // want here.  While the compiler will always(?) set up LR for
-  // subroutine calls, it may not for leaf functions (such as this one).
-  // This routine forces the compiler (at least gcc) to push it anyway.
-  AbslStacktracePowerPCDummyFunction();
-
-  // The LR save area is used by the callee, so the top entry is bogus.
-  skip_count++;
-
-  int n = 0;
-
-  // Unlike ABIs of X86 and ARM, PowerPC ABIs say that return address (in
-  // the link register) of a function call is stored in the caller's stack
-  // frame instead of the callee's.  When we look for the return address
-  // associated with a stack frame, we need to make sure that there is a
-  // caller frame before it.  So we call NextStackFrame before entering the
-  // loop below and check next_sp instead of sp for loop termination.
-  // The outermost frame is set up by runtimes and it does not have a
-  // caller frame, so it is skipped.
-
-  // The absl::GetStackFrames routine is called when we are in some
-  // informational context (the failure signal handler for example).
-  // Use the non-strict unwinding rules to produce a stack trace
-  // that is as complete as possible (even if it contains a few
-  // bogus entries in some rare cases).
-  void **next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(sp, ucp);
-
-  while (next_sp && n < max_depth) {
-    if (skip_count > 0) {
-      skip_count--;
-    } else {
-      result[n] = StacktracePowerPCGetLR(sp);
-      if (IS_STACK_FRAMES) {
-        if (next_sp > sp) {
-          sizes[n] = (uintptr_t)next_sp - (uintptr_t)sp;
-        } else {
-          // A frame-size of 0 is used to indicate unknown frame size.
-          sizes[n] = 0;
-        }
-      }
-      n++;
-    }
-
-    sp = next_sp;
-    next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(sp, ucp);
-  }
-
-  if (min_dropped_frames != nullptr) {
-    // Implementation detail: we clamp the max of frames we are willing to
-    // count, so as not to spend too much time in the loop below.
-    const int kMaxUnwind = 1000;
-    int j = 0;
-    for (; next_sp != nullptr && j < kMaxUnwind; j++) {
-      next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(next_sp, ucp);
-    }
-    *min_dropped_frames = j;
-  }
-  return n;
-}
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-bool StackTraceWorksForTest() {
-  return true;
-}
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_POWERPC_INL_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_unimplemented-inl.inc b/third_party/abseil_cpp/absl/debugging/internal/stacktrace_unimplemented-inl.inc
deleted file mode 100644
index 5b8fb191b65a..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_unimplemented-inl.inc
+++ /dev/null
@@ -1,24 +0,0 @@
-#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_
-#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_
-
-template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
-static int UnwindImpl(void** /* result */, int* /* sizes */,
-                      int /* max_depth */, int /* skip_count */,
-                      const void* /* ucp */, int *min_dropped_frames) {
-  if (min_dropped_frames != nullptr) {
-    *min_dropped_frames = 0;
-  }
-  return 0;
-}
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-bool StackTraceWorksForTest() {
-  return false;
-}
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_win32-inl.inc b/third_party/abseil_cpp/absl/debugging/internal/stacktrace_win32-inl.inc
deleted file mode 100644
index 1c666c8b561f..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_win32-inl.inc
+++ /dev/null
@@ -1,93 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-// Produces a stack trace for Windows.  Normally, one could use
-// stacktrace_x86-inl.h or stacktrace_x86_64-inl.h -- and indeed, that
-// should work for binaries compiled using MSVC in "debug" mode.
-// However, in "release" mode, Windows uses frame-pointer
-// optimization, which makes getting a stack trace very difficult.
-//
-// There are several approaches one can take.  One is to use Windows
-// intrinsics like StackWalk64.  These can work, but have restrictions
-// on how successful they can be.  Another attempt is to write a
-// version of stacktrace_x86-inl.h that has heuristic support for
-// dealing with FPO, similar to what WinDbg does (see
-// http://www.nynaeve.net/?p=97).  There are (non-working) examples of
-// these approaches, complete with TODOs, in stacktrace_win32-inl.h#1
-//
-// The solution we've ended up doing is to call the undocumented
-// windows function RtlCaptureStackBackTrace, which probably doesn't
-// work with FPO but at least is fast, and doesn't require a symbol
-// server.
-//
-// This code is inspired by a patch from David Vitek:
-//   https://code.google.com/p/google-perftools/issues/detail?id=83
-
-#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_
-#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_
-
-#include <windows.h>    // for GetProcAddress and GetModuleHandle
-#include <cassert>
-
-typedef USHORT NTAPI RtlCaptureStackBackTrace_Function(
-    IN ULONG frames_to_skip,
-    IN ULONG frames_to_capture,
-    OUT PVOID *backtrace,
-    OUT PULONG backtrace_hash);
-
-// It is not possible to load RtlCaptureStackBackTrace at static init time in
-// UWP. CaptureStackBackTrace is the public version of RtlCaptureStackBackTrace
-#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP) && \
-    !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
-static RtlCaptureStackBackTrace_Function* const RtlCaptureStackBackTrace_fn =
-    &::CaptureStackBackTrace;
-#else
-// Load the function we need at static init time, where we don't have
-// to worry about someone else holding the loader's lock.
-static RtlCaptureStackBackTrace_Function* const RtlCaptureStackBackTrace_fn =
-    (RtlCaptureStackBackTrace_Function*)GetProcAddress(
-        GetModuleHandleA("ntdll.dll"), "RtlCaptureStackBackTrace");
-#endif  // WINAPI_PARTITION_APP && !WINAPI_PARTITION_DESKTOP
-
-template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
-static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
-                      const void*, int* min_dropped_frames) {
-  int n = 0;
-  if (!RtlCaptureStackBackTrace_fn) {
-    // can't find a stacktrace with no function to call
-  } else {
-    n = (int)RtlCaptureStackBackTrace_fn(skip_count + 2, max_depth, result, 0);
-  }
-  if (IS_STACK_FRAMES) {
-    // No implementation for finding out the stack frame sizes yet.
-    memset(sizes, 0, sizeof(*sizes) * n);
-  }
-  if (min_dropped_frames != nullptr) {
-    // Not implemented.
-    *min_dropped_frames = 0;
-  }
-  return n;
-}
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-bool StackTraceWorksForTest() {
-  return false;
-}
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_x86-inl.inc b/third_party/abseil_cpp/absl/debugging/internal/stacktrace_x86-inl.inc
deleted file mode 100644
index bc320ff75bc5..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/stacktrace_x86-inl.inc
+++ /dev/null
@@ -1,346 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-// Produce stack trace
-
-#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_X86_INL_INC_
-#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_X86_INL_INC_
-
-#if defined(__linux__) && (defined(__i386__) || defined(__x86_64__))
-#include <ucontext.h>  // for ucontext_t
-#endif
-
-#if !defined(_WIN32)
-#include <unistd.h>
-#endif
-
-#include <cassert>
-#include <cstdint>
-
-#include "absl/base/macros.h"
-#include "absl/base/port.h"
-#include "absl/debugging/internal/address_is_readable.h"
-#include "absl/debugging/internal/vdso_support.h"  // a no-op on non-elf or non-glibc systems
-#include "absl/debugging/stacktrace.h"
-
-#include "absl/base/internal/raw_logging.h"
-
-using absl::debugging_internal::AddressIsReadable;
-
-#if defined(__linux__) && defined(__i386__)
-// Count "push %reg" instructions in VDSO __kernel_vsyscall(),
-// preceeding "syscall" or "sysenter".
-// If __kernel_vsyscall uses frame pointer, answer 0.
-//
-// kMaxBytes tells how many instruction bytes of __kernel_vsyscall
-// to analyze before giving up. Up to kMaxBytes+1 bytes of
-// instructions could be accessed.
-//
-// Here are known __kernel_vsyscall instruction sequences:
-//
-// SYSENTER (linux-2.6.26/arch/x86/vdso/vdso32/sysenter.S).
-// Used on Intel.
-//  0xffffe400 <__kernel_vsyscall+0>:       push   %ecx
-//  0xffffe401 <__kernel_vsyscall+1>:       push   %edx
-//  0xffffe402 <__kernel_vsyscall+2>:       push   %ebp
-//  0xffffe403 <__kernel_vsyscall+3>:       mov    %esp,%ebp
-//  0xffffe405 <__kernel_vsyscall+5>:       sysenter
-//
-// SYSCALL (see linux-2.6.26/arch/x86/vdso/vdso32/syscall.S).
-// Used on AMD.
-//  0xffffe400 <__kernel_vsyscall+0>:       push   %ebp
-//  0xffffe401 <__kernel_vsyscall+1>:       mov    %ecx,%ebp
-//  0xffffe403 <__kernel_vsyscall+3>:       syscall
-//
-
-// The sequence below isn't actually expected in Google fleet,
-// here only for completeness. Remove this comment from OSS release.
-
-// i386 (see linux-2.6.26/arch/x86/vdso/vdso32/int80.S)
-//  0xffffe400 <__kernel_vsyscall+0>:       int $0x80
-//  0xffffe401 <__kernel_vsyscall+1>:       ret
-//
-static const int kMaxBytes = 10;
-
-// We use assert()s instead of DCHECK()s -- this is too low level
-// for DCHECK().
-
-static int CountPushInstructions(const unsigned char *const addr) {
-  int result = 0;
-  for (int i = 0; i < kMaxBytes; ++i) {
-    if (addr[i] == 0x89) {
-      // "mov reg,reg"
-      if (addr[i + 1] == 0xE5) {
-        // Found "mov %esp,%ebp".
-        return 0;
-      }
-      ++i;  // Skip register encoding byte.
-    } else if (addr[i] == 0x0F &&
-               (addr[i + 1] == 0x34 || addr[i + 1] == 0x05)) {
-      // Found "sysenter" or "syscall".
-      return result;
-    } else if ((addr[i] & 0xF0) == 0x50) {
-      // Found "push %reg".
-      ++result;
-    } else if (addr[i] == 0xCD && addr[i + 1] == 0x80) {
-      // Found "int $0x80"
-      assert(result == 0);
-      return 0;
-    } else {
-      // Unexpected instruction.
-      assert(false && "unexpected instruction in __kernel_vsyscall");
-      return 0;
-    }
-  }
-  // Unexpected: didn't find SYSENTER or SYSCALL in
-  // [__kernel_vsyscall, __kernel_vsyscall + kMaxBytes) interval.
-  assert(false && "did not find SYSENTER or SYSCALL in __kernel_vsyscall");
-  return 0;
-}
-#endif
-
-// Assume stack frames larger than 100,000 bytes are bogus.
-static const int kMaxFrameBytes = 100000;
-
-// Returns the stack frame pointer from signal context, 0 if unknown.
-// vuc is a ucontext_t *.  We use void* to avoid the use
-// of ucontext_t on non-POSIX systems.
-static uintptr_t GetFP(const void *vuc) {
-#if !defined(__linux__)
-  static_cast<void>(vuc);  // Avoid an unused argument compiler warning.
-#else
-  if (vuc != nullptr) {
-    auto *uc = reinterpret_cast<const ucontext_t *>(vuc);
-#if defined(__i386__)
-    const auto bp = uc->uc_mcontext.gregs[REG_EBP];
-    const auto sp = uc->uc_mcontext.gregs[REG_ESP];
-#elif defined(__x86_64__)
-    const auto bp = uc->uc_mcontext.gregs[REG_RBP];
-    const auto sp = uc->uc_mcontext.gregs[REG_RSP];
-#else
-    const uintptr_t bp = 0;
-    const uintptr_t sp = 0;
-#endif
-    // Sanity-check that the base pointer is valid.  It should be as long as
-    // SHRINK_WRAP_FRAME_POINTER is not set, but it's possible that some code in
-    // the process is compiled with --copt=-fomit-frame-pointer or
-    // --copt=-momit-leaf-frame-pointer.
-    //
-    // TODO(bcmills): -momit-leaf-frame-pointer is currently the default
-    // behavior when building with clang.  Talk to the C++ toolchain team about
-    // fixing that.
-    if (bp >= sp && bp - sp <= kMaxFrameBytes) return bp;
-
-    // If bp isn't a plausible frame pointer, return the stack pointer instead.
-    // If we're lucky, it points to the start of a stack frame; otherwise, we'll
-    // get one frame of garbage in the stack trace and fail the sanity check on
-    // the next iteration.
-    return sp;
-  }
-#endif
-  return 0;
-}
-
-// Given a pointer to a stack frame, locate and return the calling
-// stackframe, or return null if no stackframe can be found. Perform sanity
-// checks (the strictness of which is controlled by the boolean parameter
-// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
-template <bool STRICT_UNWINDING, bool WITH_CONTEXT>
-ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS  // May read random elements from stack.
-ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY   // May read random elements from stack.
-static void **NextStackFrame(void **old_fp, const void *uc) {
-  void **new_fp = (void **)*old_fp;
-
-#if defined(__linux__) && defined(__i386__)
-  if (WITH_CONTEXT && uc != nullptr) {
-    // How many "push %reg" instructions are there at __kernel_vsyscall?
-    // This is constant for a given kernel and processor, so compute
-    // it only once.
-    static int num_push_instructions = -1;  // Sentinel: not computed yet.
-    // Initialize with sentinel value: __kernel_rt_sigreturn can not possibly
-    // be there.
-    static const unsigned char *kernel_rt_sigreturn_address = nullptr;
-    static const unsigned char *kernel_vsyscall_address = nullptr;
-    if (num_push_instructions == -1) {
-#ifdef ABSL_HAVE_VDSO_SUPPORT
-      absl::debugging_internal::VDSOSupport vdso;
-      if (vdso.IsPresent()) {
-        absl::debugging_internal::VDSOSupport::SymbolInfo
-            rt_sigreturn_symbol_info;
-        absl::debugging_internal::VDSOSupport::SymbolInfo vsyscall_symbol_info;
-        if (!vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_2.5", STT_FUNC,
-                               &rt_sigreturn_symbol_info) ||
-            !vdso.LookupSymbol("__kernel_vsyscall", "LINUX_2.5", STT_FUNC,
-                               &vsyscall_symbol_info) ||
-            rt_sigreturn_symbol_info.address == nullptr ||
-            vsyscall_symbol_info.address == nullptr) {
-          // Unexpected: 32-bit VDSO is present, yet one of the expected
-          // symbols is missing or null.
-          assert(false && "VDSO is present, but doesn't have expected symbols");
-          num_push_instructions = 0;
-        } else {
-          kernel_rt_sigreturn_address =
-              reinterpret_cast<const unsigned char *>(
-                  rt_sigreturn_symbol_info.address);
-          kernel_vsyscall_address =
-              reinterpret_cast<const unsigned char *>(
-                  vsyscall_symbol_info.address);
-          num_push_instructions =
-              CountPushInstructions(kernel_vsyscall_address);
-        }
-      } else {
-        num_push_instructions = 0;
-      }
-#else  // ABSL_HAVE_VDSO_SUPPORT
-      num_push_instructions = 0;
-#endif  // ABSL_HAVE_VDSO_SUPPORT
-    }
-    if (num_push_instructions != 0 && kernel_rt_sigreturn_address != nullptr &&
-        old_fp[1] == kernel_rt_sigreturn_address) {
-      const ucontext_t *ucv = static_cast<const ucontext_t *>(uc);
-      // This kernel does not use frame pointer in its VDSO code,
-      // and so %ebp is not suitable for unwinding.
-      void **const reg_ebp =
-          reinterpret_cast<void **>(ucv->uc_mcontext.gregs[REG_EBP]);
-      const unsigned char *const reg_eip =
-          reinterpret_cast<unsigned char *>(ucv->uc_mcontext.gregs[REG_EIP]);
-      if (new_fp == reg_ebp && kernel_vsyscall_address <= reg_eip &&
-          reg_eip - kernel_vsyscall_address < kMaxBytes) {
-        // We "stepped up" to __kernel_vsyscall, but %ebp is not usable.
-        // Restore from 'ucv' instead.
-        void **const reg_esp =
-            reinterpret_cast<void **>(ucv->uc_mcontext.gregs[REG_ESP]);
-        // Check that alleged %esp is not null and is reasonably aligned.
-        if (reg_esp &&
-            ((uintptr_t)reg_esp & (sizeof(reg_esp) - 1)) == 0) {
-          // Check that alleged %esp is actually readable. This is to prevent
-          // "double fault" in case we hit the first fault due to e.g. stack
-          // corruption.
-          void *const reg_esp2 = reg_esp[num_push_instructions - 1];
-          if (AddressIsReadable(reg_esp2)) {
-            // Alleged %esp is readable, use it for further unwinding.
-            new_fp = reinterpret_cast<void **>(reg_esp2);
-          }
-        }
-      }
-    }
-  }
-#endif
-
-  const uintptr_t old_fp_u = reinterpret_cast<uintptr_t>(old_fp);
-  const uintptr_t new_fp_u = reinterpret_cast<uintptr_t>(new_fp);
-
-  // Check that the transition from frame pointer old_fp to frame
-  // pointer new_fp isn't clearly bogus.  Skip the checks if new_fp
-  // matches the signal context, so that we don't skip out early when
-  // using an alternate signal stack.
-  //
-  // TODO(bcmills): The GetFP call should be completely unnecessary when
-  // SHRINK_WRAP_FRAME_POINTER is set (because we should be back in the thread's
-  // stack by this point), but it is empirically still needed (e.g. when the
-  // stack includes a call to abort).  unw_get_reg returns UNW_EBADREG for some
-  // frames.  Figure out why GetValidFrameAddr and/or libunwind isn't doing what
-  // it's supposed to.
-  if (STRICT_UNWINDING &&
-      (!WITH_CONTEXT || uc == nullptr || new_fp_u != GetFP(uc))) {
-    // With the stack growing downwards, older stack frame must be
-    // at a greater address that the current one.
-    if (new_fp_u <= old_fp_u) return nullptr;
-    if (new_fp_u - old_fp_u > kMaxFrameBytes) return nullptr;
-  } else {
-    if (new_fp == nullptr) return nullptr;  // skip AddressIsReadable() below
-    // In the non-strict mode, allow discontiguous stack frames.
-    // (alternate-signal-stacks for example).
-    if (new_fp == old_fp) return nullptr;
-  }
-
-  if (new_fp_u & (sizeof(void *) - 1)) return nullptr;
-#ifdef __i386__
-  // On 32-bit machines, the stack pointer can be very close to
-  // 0xffffffff, so we explicitly check for a pointer into the
-  // last two pages in the address space
-  if (new_fp_u >= 0xffffe000) return nullptr;
-#endif
-#if !defined(_WIN32)
-  if (!STRICT_UNWINDING) {
-    // Lax sanity checks cause a crash in 32-bit tcmalloc/crash_reason_test
-    // on AMD-based machines with VDSO-enabled kernels.
-    // Make an extra sanity check to insure new_fp is readable.
-    // Note: NextStackFrame<false>() is only called while the program
-    //       is already on its last leg, so it's ok to be slow here.
-
-    if (!AddressIsReadable(new_fp)) {
-      return nullptr;
-    }
-  }
-#endif
-  return new_fp;
-}
-
-template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
-ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS  // May read random elements from stack.
-ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY   // May read random elements from stack.
-ABSL_ATTRIBUTE_NOINLINE
-static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
-                      const void *ucp, int *min_dropped_frames) {
-  int n = 0;
-  void **fp = reinterpret_cast<void **>(__builtin_frame_address(0));
-
-  while (fp && n < max_depth) {
-    if (*(fp + 1) == reinterpret_cast<void *>(0)) {
-      // In 64-bit code, we often see a frame that
-      // points to itself and has a return address of 0.
-      break;
-    }
-    void **next_fp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(fp, ucp);
-    if (skip_count > 0) {
-      skip_count--;
-    } else {
-      result[n] = *(fp + 1);
-      if (IS_STACK_FRAMES) {
-        if (next_fp > fp) {
-          sizes[n] = (uintptr_t)next_fp - (uintptr_t)fp;
-        } else {
-          // A frame-size of 0 is used to indicate unknown frame size.
-          sizes[n] = 0;
-        }
-      }
-      n++;
-    }
-    fp = next_fp;
-  }
-  if (min_dropped_frames != nullptr) {
-    // Implementation detail: we clamp the max of frames we are willing to
-    // count, so as not to spend too much time in the loop below.
-    const int kMaxUnwind = 1000;
-    int j = 0;
-    for (; fp != nullptr && j < kMaxUnwind; j++) {
-      fp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(fp, ucp);
-    }
-    *min_dropped_frames = j;
-  }
-  return n;
-}
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-bool StackTraceWorksForTest() {
-  return true;
-}
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_X86_INL_INC_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/symbolize.h b/third_party/abseil_cpp/absl/debugging/internal/symbolize.h
deleted file mode 100644
index 4f26130fbb71..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/symbolize.h
+++ /dev/null
@@ -1,147 +0,0 @@
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// This file contains internal parts of the Abseil symbolizer.
-// Do not depend on the anything in this file, it may change at anytime.
-
-#ifndef ABSL_DEBUGGING_INTERNAL_SYMBOLIZE_H_
-#define ABSL_DEBUGGING_INTERNAL_SYMBOLIZE_H_
-
-#ifdef __cplusplus
-
-#include <cstddef>
-#include <cstdint>
-
-#include "absl/base/config.h"
-#include "absl/strings/string_view.h"
-
-#ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
-#error ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE cannot be directly set
-#elif defined(__ELF__) && defined(__GLIBC__) && !defined(__native_client__) && \
-    !defined(__asmjs__) && !defined(__wasm__)
-#define ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE 1
-
-#include <elf.h>
-#include <link.h>  // For ElfW() macro.
-#include <functional>
-#include <string>
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-// Iterates over all sections, invoking callback on each with the section name
-// and the section header.
-//
-// Returns true on success; otherwise returns false in case of errors.
-//
-// This is not async-signal-safe.
-bool ForEachSection(int fd,
-                    const std::function<bool(absl::string_view name,
-                                             const ElfW(Shdr) &)>& callback);
-
-// Gets the section header for the given name, if it exists. Returns true on
-// success. Otherwise, returns false.
-bool GetSectionHeaderByName(int fd, const char *name, size_t name_len,
-                            ElfW(Shdr) *out);
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
-
-#ifdef ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE
-#error ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE cannot be directly set
-#elif defined(__APPLE__)
-#define ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE 1
-#endif
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-struct SymbolDecoratorArgs {
-  // The program counter we are getting symbolic name for.
-  const void *pc;
-  // 0 for main executable, load address for shared libraries.
-  ptrdiff_t relocation;
-  // Read-only file descriptor for ELF image covering "pc",
-  // or -1 if no such ELF image exists in /proc/self/maps.
-  int fd;
-  // Output buffer, size.
-  // Note: the buffer may not be empty -- default symbolizer may have already
-  // produced some output, and earlier decorators may have adorned it in
-  // some way. You are free to replace or augment the contents (within the
-  // symbol_buf_size limit).
-  char *const symbol_buf;
-  size_t symbol_buf_size;
-  // Temporary scratch space, size.
-  // Use that space in preference to allocating your own stack buffer to
-  // conserve stack.
-  char *const tmp_buf;
-  size_t tmp_buf_size;
-  // User-provided argument
-  void* arg;
-};
-using SymbolDecorator = void (*)(const SymbolDecoratorArgs *);
-
-// Installs a function-pointer as a decorator. Returns a value less than zero
-// if the system cannot install the decorator. Otherwise, returns a unique
-// identifier corresponding to the decorator. This identifier can be used to
-// uninstall the decorator - See RemoveSymbolDecorator() below.
-int InstallSymbolDecorator(SymbolDecorator decorator, void* arg);
-
-// Removes a previously installed function-pointer decorator. Parameter "ticket"
-// is the return-value from calling InstallSymbolDecorator().
-bool RemoveSymbolDecorator(int ticket);
-
-// Remove all installed decorators.  Returns true if successful, false if
-// symbolization is currently in progress.
-bool RemoveAllSymbolDecorators(void);
-
-// Registers an address range to a file mapping.
-//
-// Preconditions:
-//   start <= end
-//   filename != nullptr
-//
-// Returns true if the file was successfully registered.
-bool RegisterFileMappingHint(const void* start, const void* end,
-                             uint64_t offset, const char* filename);
-
-// Looks up the file mapping registered by RegisterFileMappingHint for an
-// address range. If there is one, the file name is stored in *filename and
-// *start and *end are modified to reflect the registered mapping. Returns
-// whether any hint was found.
-bool GetFileMappingHint(const void** start, const void** end, uint64_t* offset,
-                        const char** filename);
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // __cplusplus
-
-#include <stdbool.h>
-
-#ifdef __cplusplus
-extern "C"
-#endif  // __cplusplus
-
-    bool
-    AbslInternalGetFileMappingHint(const void** start, const void** end,
-                                   uint64_t* offset, const char** filename);
-
-#endif  // ABSL_DEBUGGING_INTERNAL_SYMBOLIZE_H_
diff --git a/third_party/abseil_cpp/absl/debugging/internal/vdso_support.cc b/third_party/abseil_cpp/absl/debugging/internal/vdso_support.cc
deleted file mode 100644
index 6be16d907275..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/vdso_support.cc
+++ /dev/null
@@ -1,173 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Allow dynamic symbol lookup in the kernel VDSO page.
-//
-// VDSOSupport -- a class representing kernel VDSO (if present).
-
-#include "absl/debugging/internal/vdso_support.h"
-
-#ifdef ABSL_HAVE_VDSO_SUPPORT     // defined in vdso_support.h
-
-#include <errno.h>
-#include <fcntl.h>
-#include <sys/syscall.h>
-#include <unistd.h>
-
-#if __GLIBC_PREREQ(2, 16)  // GLIBC-2.16 implements getauxval.
-#include <sys/auxv.h>
-#endif
-
-#include "absl/base/dynamic_annotations.h"
-#include "absl/base/internal/raw_logging.h"
-#include "absl/base/port.h"
-
-#ifndef AT_SYSINFO_EHDR
-#define AT_SYSINFO_EHDR 33  // for crosstoolv10
-#endif
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-ABSL_CONST_INIT
-std::atomic<const void *> VDSOSupport::vdso_base_(
-    debugging_internal::ElfMemImage::kInvalidBase);
-
-std::atomic<VDSOSupport::GetCpuFn> VDSOSupport::getcpu_fn_(&InitAndGetCPU);
-VDSOSupport::VDSOSupport()
-    // If vdso_base_ is still set to kInvalidBase, we got here
-    // before VDSOSupport::Init has been called. Call it now.
-    : image_(vdso_base_.load(std::memory_order_relaxed) ==
-                     debugging_internal::ElfMemImage::kInvalidBase
-                 ? Init()
-                 : vdso_base_.load(std::memory_order_relaxed)) {}
-
-// NOTE: we can't use GoogleOnceInit() below, because we can be
-// called by tcmalloc, and none of the *once* stuff may be functional yet.
-//
-// In addition, we hope that the VDSOSupportHelper constructor
-// causes this code to run before there are any threads, and before
-// InitGoogle() has executed any chroot or setuid calls.
-//
-// Finally, even if there is a race here, it is harmless, because
-// the operation should be idempotent.
-const void *VDSOSupport::Init() {
-  const auto kInvalidBase = debugging_internal::ElfMemImage::kInvalidBase;
-#if __GLIBC_PREREQ(2, 16)
-  if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) {
-    errno = 0;
-    const void *const sysinfo_ehdr =
-        reinterpret_cast<const void *>(getauxval(AT_SYSINFO_EHDR));
-    if (errno == 0) {
-      vdso_base_.store(sysinfo_ehdr, std::memory_order_relaxed);
-    }
-  }
-#endif  // __GLIBC_PREREQ(2, 16)
-  if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) {
-    int fd = open("/proc/self/auxv", O_RDONLY);
-    if (fd == -1) {
-      // Kernel too old to have a VDSO.
-      vdso_base_.store(nullptr, std::memory_order_relaxed);
-      getcpu_fn_.store(&GetCPUViaSyscall, std::memory_order_relaxed);
-      return nullptr;
-    }
-    ElfW(auxv_t) aux;
-    while (read(fd, &aux, sizeof(aux)) == sizeof(aux)) {
-      if (aux.a_type == AT_SYSINFO_EHDR) {
-        vdso_base_.store(reinterpret_cast<void *>(aux.a_un.a_val),
-                         std::memory_order_relaxed);
-        break;
-      }
-    }
-    close(fd);
-    if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) {
-      // Didn't find AT_SYSINFO_EHDR in auxv[].
-      vdso_base_.store(nullptr, std::memory_order_relaxed);
-    }
-  }
-  GetCpuFn fn = &GetCPUViaSyscall;  // default if VDSO not present.
-  if (vdso_base_.load(std::memory_order_relaxed)) {
-    VDSOSupport vdso;
-    SymbolInfo info;
-    if (vdso.LookupSymbol("__vdso_getcpu", "LINUX_2.6", STT_FUNC, &info)) {
-      fn = reinterpret_cast<GetCpuFn>(const_cast<void *>(info.address));
-    }
-  }
-  // Subtle: this code runs outside of any locks; prevent compiler
-  // from assigning to getcpu_fn_ more than once.
-  getcpu_fn_.store(fn, std::memory_order_relaxed);
-  return vdso_base_.load(std::memory_order_relaxed);
-}
-
-const void *VDSOSupport::SetBase(const void *base) {
-  ABSL_RAW_CHECK(base != debugging_internal::ElfMemImage::kInvalidBase,
-                 "internal error");
-  const void *old_base = vdso_base_.load(std::memory_order_relaxed);
-  vdso_base_.store(base, std::memory_order_relaxed);
-  image_.Init(base);
-  // Also reset getcpu_fn_, so GetCPU could be tested with simulated VDSO.
-  getcpu_fn_.store(&InitAndGetCPU, std::memory_order_relaxed);
-  return old_base;
-}
-
-bool VDSOSupport::LookupSymbol(const char *name,
-                               const char *version,
-                               int type,
-                               SymbolInfo *info) const {
-  return image_.LookupSymbol(name, version, type, info);
-}
-
-bool VDSOSupport::LookupSymbolByAddress(const void *address,
-                                        SymbolInfo *info_out) const {
-  return image_.LookupSymbolByAddress(address, info_out);
-}
-
-// NOLINT on 'long' because this routine mimics kernel api.
-long VDSOSupport::GetCPUViaSyscall(unsigned *cpu,  // NOLINT(runtime/int)
-                                   void *, void *) {
-#ifdef SYS_getcpu
-  return syscall(SYS_getcpu, cpu, nullptr, nullptr);
-#else
-  // x86_64 never implemented sys_getcpu(), except as a VDSO call.
-  static_cast<void>(cpu);  // Avoid an unused argument compiler warning.
-  errno = ENOSYS;
-  return -1;
-#endif
-}
-
-// Use fast __vdso_getcpu if available.
-long VDSOSupport::InitAndGetCPU(unsigned *cpu,  // NOLINT(runtime/int)
-                                void *x, void *y) {
-  Init();
-  GetCpuFn fn = getcpu_fn_.load(std::memory_order_relaxed);
-  ABSL_RAW_CHECK(fn != &InitAndGetCPU, "Init() did not set getcpu_fn_");
-  return (*fn)(cpu, x, y);
-}
-
-// This function must be very fast, and may be called from very
-// low level (e.g. tcmalloc). Hence I avoid things like
-// GoogleOnceInit() and ::operator new.
-ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY
-int GetCPU() {
-  unsigned cpu;
-  int ret_code = (*VDSOSupport::getcpu_fn_)(&cpu, nullptr, nullptr);
-  return ret_code == 0 ? cpu : ret_code;
-}
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_HAVE_VDSO_SUPPORT
diff --git a/third_party/abseil_cpp/absl/debugging/internal/vdso_support.h b/third_party/abseil_cpp/absl/debugging/internal/vdso_support.h
deleted file mode 100644
index 6562c6c2350a..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/vdso_support.h
+++ /dev/null
@@ -1,158 +0,0 @@
-//
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-
-// Allow dynamic symbol lookup in the kernel VDSO page.
-//
-// VDSO stands for "Virtual Dynamic Shared Object" -- a page of
-// executable code, which looks like a shared library, but doesn't
-// necessarily exist anywhere on disk, and which gets mmap()ed into
-// every process by kernels which support VDSO, such as 2.6.x for 32-bit
-// executables, and 2.6.24 and above for 64-bit executables.
-//
-// More details could be found here:
-// http://www.trilithium.com/johan/2005/08/linux-gate/
-//
-// VDSOSupport -- a class representing kernel VDSO (if present).
-//
-// Example usage:
-//  VDSOSupport vdso;
-//  VDSOSupport::SymbolInfo info;
-//  typedef (*FN)(unsigned *, void *, void *);
-//  FN fn = nullptr;
-//  if (vdso.LookupSymbol("__vdso_getcpu", "LINUX_2.6", STT_FUNC, &info)) {
-//     fn = reinterpret_cast<FN>(info.address);
-//  }
-
-#ifndef ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_
-#define ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_
-
-#include <atomic>
-
-#include "absl/base/attributes.h"
-#include "absl/debugging/internal/elf_mem_image.h"
-
-#ifdef ABSL_HAVE_ELF_MEM_IMAGE
-
-#ifdef ABSL_HAVE_VDSO_SUPPORT
-#error ABSL_HAVE_VDSO_SUPPORT cannot be directly set
-#else
-#define ABSL_HAVE_VDSO_SUPPORT 1
-#endif
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-// NOTE: this class may be used from within tcmalloc, and can not
-// use any memory allocation routines.
-class VDSOSupport {
- public:
-  VDSOSupport();
-
-  typedef ElfMemImage::SymbolInfo SymbolInfo;
-  typedef ElfMemImage::SymbolIterator SymbolIterator;
-
-  // On PowerPC64 VDSO symbols can either be of type STT_FUNC or STT_NOTYPE
-  // depending on how the kernel is built.  The kernel is normally built with
-  // STT_NOTYPE type VDSO symbols.  Let's make things simpler first by using a
-  // compile-time constant.
-#ifdef __powerpc64__
-  enum { kVDSOSymbolType = STT_NOTYPE };
-#else
-  enum { kVDSOSymbolType = STT_FUNC };
-#endif
-
-  // Answers whether we have a vdso at all.
-  bool IsPresent() const { return image_.IsPresent(); }
-
-  // Allow to iterate over all VDSO symbols.
-  SymbolIterator begin() const { return image_.begin(); }
-  SymbolIterator end() const { return image_.end(); }
-
-  // Look up versioned dynamic symbol in the kernel VDSO.
-  // Returns false if VDSO is not present, or doesn't contain given
-  // symbol/version/type combination.
-  // If info_out != nullptr, additional details are filled in.
-  bool LookupSymbol(const char *name, const char *version,
-                    int symbol_type, SymbolInfo *info_out) const;
-
-  // Find info about symbol (if any) which overlaps given address.
-  // Returns true if symbol was found; false if VDSO isn't present
-  // or doesn't have a symbol overlapping given address.
-  // If info_out != nullptr, additional details are filled in.
-  bool LookupSymbolByAddress(const void *address, SymbolInfo *info_out) const;
-
-  // Used only for testing. Replace real VDSO base with a mock.
-  // Returns previous value of vdso_base_. After you are done testing,
-  // you are expected to call SetBase() with previous value, in order to
-  // reset state to the way it was.
-  const void *SetBase(const void *s);
-
-  // Computes vdso_base_ and returns it. Should be called as early as
-  // possible; before any thread creation, chroot or setuid.
-  static const void *Init();
-
- private:
-  // image_ represents VDSO ELF image in memory.
-  // image_.ehdr_ == nullptr implies there is no VDSO.
-  ElfMemImage image_;
-
-  // Cached value of auxv AT_SYSINFO_EHDR, computed once.
-  // This is a tri-state:
-  //   kInvalidBase   => value hasn't been determined yet.
-  //              0   => there is no VDSO.
-  //           else   => vma of VDSO Elf{32,64}_Ehdr.
-  //
-  // When testing with mock VDSO, low bit is set.
-  // The low bit is always available because vdso_base_ is
-  // page-aligned.
-  static std::atomic<const void *> vdso_base_;
-
-  // NOLINT on 'long' because these routines mimic kernel api.
-  // The 'cache' parameter may be used by some versions of the kernel,
-  // and should be nullptr or point to a static buffer containing at
-  // least two 'long's.
-  static long InitAndGetCPU(unsigned *cpu, void *cache,     // NOLINT 'long'.
-                            void *unused);
-  static long GetCPUViaSyscall(unsigned *cpu, void *cache,  // NOLINT 'long'.
-                               void *unused);
-  typedef long (*GetCpuFn)(unsigned *cpu, void *cache,      // NOLINT 'long'.
-                           void *unused);
-
-  // This function pointer may point to InitAndGetCPU,
-  // GetCPUViaSyscall, or __vdso_getcpu at different stages of initialization.
-  ABSL_CONST_INIT static std::atomic<GetCpuFn> getcpu_fn_;
-
-  friend int GetCPU(void);  // Needs access to getcpu_fn_.
-
-  VDSOSupport(const VDSOSupport&) = delete;
-  VDSOSupport& operator=(const VDSOSupport&) = delete;
-};
-
-// Same as sched_getcpu() on later glibc versions.
-// Return current CPU, using (fast) __vdso_getcpu@LINUX_2.6 if present,
-// otherwise use syscall(SYS_getcpu,...).
-// May return -1 with errno == ENOSYS if the kernel doesn't
-// support SYS_getcpu.
-int GetCPU();
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-#endif  // ABSL_HAVE_ELF_MEM_IMAGE
-
-#endif  // ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_