mozglue/build/cygprofile.cpp

   1 // Copyright (c) 2017 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4 //
   5 // Copied from Chromium's /src/tools/cygprofile_win/cygprofile.cc.
   6
   7 #include <stdio.h>
   8 #include <atomic>
   9 #include <string>
  10 #include <unordered_set>
  11
  12 #include <windows.h>  // Needs to be included before the others.
  13
  14 #include <dbghelp.h>
  15 #include <process.h>
  16
  17 #include "mozilla/Sprintf.h"
  18 #include "mozilla/Types.h"
  19
  20 namespace {
  21
  22 // The main purpose of the order file is to optimize startup time,
  23 // so capturing the first N function calls is enough.
  24 static constexpr int kSamplesCapacity = 25 * 1024 * 1024;
  25
  26 void* samples[kSamplesCapacity];
  27 std::atomic_int num_samples;
  28 std::atomic_int done;
  29
  30 // Symbolize the samples and write them to disk.
  31 void dump(void*) {
  32   HMODULE dbghelp = LoadLibraryA("dbghelp.dll");
  33   auto sym_from_addr = reinterpret_cast<decltype(::SymFromAddr)*>(
  34       ::GetProcAddress(dbghelp, "SymFromAddr"));
  35   auto sym_initialize = reinterpret_cast<decltype(::SymInitialize)*>(
  36       ::GetProcAddress(dbghelp, "SymInitialize"));
  37   auto sym_set_options = reinterpret_cast<decltype(::SymSetOptions)*>(
  38       ::GetProcAddress(dbghelp, "SymSetOptions"));
  39
  40   // Path to the dump file. %s will be substituted by objdir path.
  41   static const char kDumpFile[] = "%s/cygprofile.txt";
  42
  43   char filename[MAX_PATH];
  44   const char* objdir = ::getenv("MOZ_OBJDIR");
  45
  46   if (!objdir) {
  47     fprintf(stderr, "ERROR: cannot determine objdir\n");
  48     return;
  49   }
  50
  51   SprintfLiteral(filename, kDumpFile, objdir);
  52
  53   FILE* f = fopen(filename, "w");
  54   if (!f) {
  55     fprintf(stderr, "ERROR: Cannot open %s\n", filename);
  56     return;
  57   }
  58
  59   sym_initialize(::GetCurrentProcess(), NULL, TRUE);
  60   sym_set_options(SYMOPT_DEFERRED_LOADS | SYMOPT_PUBLICS_ONLY);
  61   char sym_buf[sizeof(SYMBOL_INFO) + MAX_SYM_NAME * sizeof(TCHAR)];
  62
  63   std::unordered_set<void*> seen;
  64   std::unordered_set<std::string> seen_names;
  65
  66   for (void* sample : samples) {
  67     // Only print the first call of a function.
  68     if (seen.count(sample)) continue;
  69     seen.insert(sample);
  70
  71     SYMBOL_INFO* symbol = reinterpret_cast<SYMBOL_INFO*>(sym_buf);
  72     symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
  73     symbol->MaxNameLen = MAX_SYM_NAME;
  74     DWORD64 offset = 0;
  75
  76     if (sym_from_addr(::GetCurrentProcess(), reinterpret_cast<DWORD64>(sample),
  77                       &offset, symbol)) {
  78       const char* name = symbol->Name;
  79       if (name[0] == '_') name++;
  80       if (seen_names.count(name)) continue;
  81       seen_names.insert(name);
  82
  83       fprintf(f, "%s\n", name);
  84     }
  85   }
  86
  87   fclose(f);
  88 }
  89
  90 }  // namespace
  91
  92 extern "C" {
  93
  94 MOZ_EXPORT void __cyg_profile_func_enter(void* this_fn,
  95                                          void* call_site_unused) {
  96   if (done) return;
  97
  98   // Get our index for the samples array atomically.
  99   int n = num_samples++;
 100
 101   if (n < kSamplesCapacity) {
 102     samples[n] = this_fn;
 103
 104     if (n + 1 == kSamplesCapacity) {
 105       // This is the final sample; start dumping the samples to a file (on a
 106       // separate thread so as not to disturb the main program).
 107       done = 1;
 108       _beginthread(dump, 0, nullptr);
 109     }
 110   }
 111 }
 112
 113 MOZ_EXPORT void __cyg_profile_func_exit(void* this_fn, void* call_site) {}
 114
 115 }  // extern "C"