Bug 1382076 - Use FramePointerStackWalk() in DMD on Win32. r=erahm.

The patch also uses a better value for skipFrames on Win64.

--HG--
extra : rebase_source : ef3d6d68fbea45e7fd571db2ba78904d97f5e21e

memory/replace/dmd/DMD.cpp

@@ -754,8 +754,40 @@ StackTrace::Get(Thread* aT)
   {
     AutoUnlockState unlock;
     // In each of the following cases, skipFrames is chosen so that the
-    // first frame in each stack trace is a replace_* function.
-#ifdef XP_MACOSX
+    // first frame in each stack trace is a replace_* function (or as close as
+    // possible, given the vagaries of inlining on different platforms).
+#if defined(XP_WIN) && defined(_M_IX86)
+    // This avoids MozStackWalk(), which causes unusably slow startup on Win32
+    // when it is called during static initialization (see bug 1241684).
+    //
+    // This code is cribbed from the Gecko Profiler, which also uses
+    // FramePointerStackWalk() on Win32: Registers::SyncPopulate() for the
+    // frame pointer, and GetStackTop() for the stack end.
+    CONTEXT context;
+    RtlCaptureContext(&context);
+    void* fp = reinterpret_cast<void*>(context.Ebp);
+
+    // Offset 0x18 from the FS segment register gives a pointer to the thread
+    // information block for the current thread.
+#if defined(_MSC_VER)
+    NT_TIB* pTib;
+    __asm {
+      MOV EAX, FS:[18h]
+      MOV pTib, EAX
+    }
+#elif defined(__GNUC__)
+    NT_TIB* pTib;
+    asm ( "movl %%fs:0x18, %0\n"
+         : "=r" (pTib)
+        );
+#else
+#   error "unknown compiler"
+#endif
+    void* stackEnd = static_cast<void*>(pTib->StackBase);
+    bool ok = FramePointerStackWalk(StackWalkCallback, /* skipFrames = */ 0,
+                                    MaxFrames, &tmp,
+                                    reinterpret_cast<void**>(fp), stackEnd);
+#elif defined(XP_MACOSX)
     // This avoids MozStackWalk(), which has become unusably slow on Mac due to
     // changes in libunwind.
     //
@@ -774,8 +806,13 @@ StackTrace::Get(Thread* aT)
                                     MaxFrames, &tmp,
                                     reinterpret_cast<void**>(fp), stackEnd);
 #else
-    bool ok = MozStackWalk(StackWalkCallback, /* skipFrames = */ 2,
-                           MaxFrames, &tmp, 0, nullptr);
+#if defined(XP_WIN) && defined(_M_X64)
+    int skipFrames = 1;
+#else
+    int skipFrames = 2;
+#endif
+    bool ok = MozStackWalk(StackWalkCallback, skipFrames, MaxFrames, &tmp, 0,
+                           nullptr);
 #endif
     if (!ok) {
       tmp.mLength = 0; // re-zero in case the stack walk function changed it