Bug 989499 - Part 1: Add a way to get the stack top. r=BenWa

tools/profiler/core/StackTop.cpp

@@ -0,0 +1,48 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifdef XP_MACOSX
+#include <mach/task.h>
+#include <mach/thread_act.h>
+#include <pthread.h>
+#elif XP_WIN
+#include <windows.h>
+#endif
+
+#include "StackTop.h"
+
+void *GetStackTop(void *guess) {
+#if defined(XP_MACOSX)
+  pthread_t thread = pthread_self();
+  return pthread_get_stackaddr_np(thread);
+#elif defined(XP_WIN)
+#if defined(_MSC_VER) && defined(_M_IX86)
+  // offset 0x18 from the FS segment register gives a pointer to
+  // the thread information block for the current thread
+  NT_TIB* pTib;
+  __asm {
+    MOV EAX, FS:[18h]
+      MOV pTib, EAX
+  }
+  return static_cast<void*>(pTib->StackBase);
+#elif defined(__GNUC__) && defined(i386)
+  // offset 0x18 from the FS segment register gives a pointer to
+  // the thread information block for the current thread
+  NT_TIB* pTib;
+  asm ( "movl %%fs:0x18, %0\n"
+       : "=r" (pTib)
+      );
+  return static_cast<void*>(pTib->StackBase);
+#elif defined(_M_X64) || defined(__x86_64)
+  PNT_TIB64 pTib = reinterpret_cast<PNT_TIB64>(NtCurrentTeb());
+  return static_cast<void*>(pTib->StackBase);
+#else
+#error Need a way to get the stack bounds on this platform (Windows)
+#endif
+#else
+  return guess;
+#endif
+}

tools/profiler/core/StackTop.h

@@ -0,0 +1,10 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZ_STACK_TOP_H
+#define MOZ_STACK_TOP_H
+void *GetStackTop(void *guess);
+#endif

tools/profiler/core/platform.cpp

@@ -950,7 +950,7 @@ void mozilla_sampler_unlock()
 #endif
 }
 
-bool mozilla_sampler_register_thread(const char* aName, void* stackTop)
+bool mozilla_sampler_register_thread(const char* aName, void* aGuessStackTop)
 {
   if (sInitCount == 0) {
     return false;
@@ -969,6 +969,7 @@ bool mozilla_sampler_register_thread(const char* aName, void* stackTop)
   PseudoStack* stack = PseudoStack::create();
   tlsPseudoStack.set(stack);
   bool isMainThread = is_main_thread_name(aName);
+  void* stackTop = GetStackTop(aGuessStackTop);
   return Sampler::RegisterCurrentThread(aName, stack, isMainThread, stackTop);
 }
 

tools/profiler/core/platform.h

@@ -57,6 +57,7 @@
 #include "PlatformMacros.h"
 #include "v8-support.h"
 #include <vector>
+#include "StackTop.h"
 
 // We need a definition of gettid(), but glibc doesn't provide a
 // wrapper for it.

tools/profiler/moz.build

@@ -32,6 +32,7 @@ if CONFIG['MOZ_ENABLE_PROFILER_SPS']:
         'core/ProfileJSONWriter.cpp',
         'core/ProfilerBacktrace.cpp',
         'core/ProfilerMarkers.cpp',
+        'core/StackTop.cpp',
         'core/SyncProfile.cpp',
         'core/ThreadInfo.cpp',
         'core/ThreadProfile.cpp',

tools/profiler/public/GeckoProfiler.h

@@ -215,7 +215,7 @@ static inline void profiler_lock() {}
 // Re-enable the profiler and notify 'profiler-unlocked'.
 static inline void profiler_unlock() {}
 
-static inline void profiler_register_thread(const char* name, void* stackTop) {}
+static inline void profiler_register_thread(const char* name, void* guessStackTop) {}
 static inline void profiler_unregister_thread() {}
 
 // These functions tell the profiler that a thread went to sleep so that we can avoid

tools/profiler/public/GeckoProfilerImpl.h

@@ -204,9 +204,9 @@ void profiler_unlock()
 }
 
 static inline
-void profiler_register_thread(const char* name, void* stackTop)
+void profiler_register_thread(const char* name, void* guessStackTop)
 {
-  mozilla_sampler_register_thread(name, stackTop);
+  mozilla_sampler_register_thread(name, guessStackTop);
 }
 
 static inline