Experiment for updating the tcmalloc chromium branch to r144 (gperftools 2.0).

third_party/tcmalloc/chromium/src/stacktrace_x86_64-inl.h

-// Copyright (c) 2005, Google Inc.
-// All rights reserved.
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// ---
-// Author: Arun Sharma
-//
-// Produce stack trace using libgcc
-
-extern "C" {
-#include <stdlib.h> // for NULL
-#include <unwind.h> // ABI defined unwinder
-#include <string.h> // for memset
-}
-#include "google/stacktrace.h"
-
-typedef struct {
-  void **result;
-  int max_depth;
-  int skip_count;
-  int count;
-} trace_arg_t;
-
-
-// Workaround for the malloc() in _Unwind_Backtrace() issue.
-static _Unwind_Reason_Code nop_backtrace(struct _Unwind_Context *uc, void *opq) {
-  return _URC_NO_REASON;
-}
-
-
-// This code is not considered ready to run until
-// static initializers run so that we are guaranteed
-// that any malloc-related initialization is done.
-static bool ready_to_run = false;
-class StackTraceInit {
- public:
-   StackTraceInit() {
-     // Extra call to force initialization
-     _Unwind_Backtrace(nop_backtrace, NULL);
-     ready_to_run = true;
-   }
-};
-
-static StackTraceInit module_initializer;  // Force initialization
-
-static _Unwind_Reason_Code GetOneFrame(struct _Unwind_Context *uc, void *opq) {
-  trace_arg_t *targ = (trace_arg_t *) opq;
-
-  if (targ->skip_count > 0) {
-    targ->skip_count--;
-  } else {
-    targ->result[targ->count++] = (void *) _Unwind_GetIP(uc);
-  }
-
-  if (targ->count == targ->max_depth)
-    return _URC_END_OF_STACK;
-
-  return _URC_NO_REASON;
-}
-
-// If you change this function, also change GetStackFrames below.
-int GetStackTrace(void** result, int max_depth, int skip_count) {
-  if (!ready_to_run)
-    return 0;
-
-  trace_arg_t targ;
-
-  skip_count += 1;         // Do not include the "GetStackTrace" frame
-
-  targ.result = result;
-  targ.max_depth = max_depth;
-  targ.skip_count = skip_count;
-  targ.count = 0;
-
-  _Unwind_Backtrace(GetOneFrame, &targ);
-
-  return targ.count;
-}
-
-// If you change this function, also change GetStackTrace above:
-//
-// This GetStackFrames routine shares a lot of code with GetStackTrace
-// above. This code could have been refactored into a common routine,
-// and then both GetStackTrace/GetStackFrames could call that routine.
-// There are two problems with that:
-//
-// (1) The performance of the refactored-code suffers substantially - the
-//     refactored needs to be able to record the stack trace when called
-//     from GetStackTrace, and both the stack trace and stack frame sizes,
-//     when called from GetStackFrames - this introduces enough new
-//     conditionals that GetStackTrace performance can degrade by as much
-//     as 50%.
-//
-// (2) Whether the refactored routine gets inlined into GetStackTrace and
-//     GetStackFrames depends on the compiler, and we can't guarantee the
-//     behavior either-way, even with "__attribute__ ((always_inline))"
-//     or "__attribute__ ((noinline))". But we need this guarantee or the
-//     frame counts may be off by one.
-//
-// Both (1) and (2) can be addressed without this code duplication, by
-// clever use of template functions, and by defining GetStackTrace and
-// GetStackFrames as macros that expand to these template functions.
-// However, this approach comes with its own set of problems - namely,
-// macros and  preprocessor trouble - for example,  if GetStackTrace
-// and/or GetStackFrames is ever defined as a member functions in some
-// class, we are in trouble.
-int GetStackFrames(void** pcs, int* sizes, int max_depth, int skip_count) {
-  if (!ready_to_run)
-    return 0;
-
-  trace_arg_t targ;
-
-  skip_count += 1;         // Do not include the "GetStackFrames" frame
-
-  targ.result = pcs;
-  targ.max_depth = max_depth;
-  targ.skip_count = skip_count;
-  targ.count = 0;
-
-  _Unwind_Backtrace(GetOneFrame, &targ);
-
-  // No implementation for finding out the stack frame sizes yet.
-  memset(sizes, 0, sizeof(*sizes) * targ.count);
-
-  return targ.count;
-}