chore(3p/abseil_cpp): unvendor abseil_cpp r/3786

we weren't actually using these sources anymore, okay?

Change-Id: If701571d9716de308d3512e1eb22c35db0877a66
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5248
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Autosubmit: tazjin <tazjin@tvl.su>

1 files changed, 0 insertions, 346 deletions

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_