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, 185 deletions

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