Fixed alignment issues of ProfilerEventsProcessor.

src/allocation.cc

Index: src/allocation.cc
diff --git a/src/allocation.cc b/src/allocation.cc
index 69edf6906cf2d03601af6bf90a98ae798c836316..a2b2b9a972a255cc9b859b21d318438aa56003b0 100644
--- a/src/allocation.cc
+++ b/src/allocation.cc
@@ -32,6 +32,16 @@
 #include "platform.h"
 #include "utils.h"
 
+#if V8_CC_MSVC

[Benedikt Meurer, 2014/01/09 10:42:52]

What about Cygwin? Does Cygwin have posix_memalign? What about mingw?

[Sven Panne, 2014/01/09 12:04:19]

Cygwin seems to have posix_memalign, and hopefully MinGW exposes the
_aligned_malloc stuff (slightly contradicting articles found on the net). I'll
change the test here to V8_OS_WIN, because IIRC a normal Cygwin build (without
-mno-cygwin) does not #define _WIN32. But let the bots decide. :-P

We really, really need to pull in Chrome's base library...

+#include <malloc.h>  // NOLINT
+#define V8_HAS__ALIGNED_MALLOC 1

[Benedikt Meurer, 2014/01/09 10:42:52]

Shouldn't these V8_HAS_* macros live in v8config.h?

[Sven Panne, 2014/01/09 12:04:19]

I don't have a strong opinion about that, up to now there are no library-related
#defines there AFACIT. Will move them to that header...

+#endif
+
+#if V8_OS_POSIX
+#include <stdlib.h>  // NOLINT

[Benedikt Meurer, 2014/01/09 10:42:52]

stdlib.h is already included above.

[Sven Panne, 2014/01/09 12:04:19]

Done.

+#define V8_HAS_POSIX_MEMALIGN 1
+#endif
+
 namespace v8 {
 namespace internal {
 
@@ -100,4 +110,48 @@ char* StrNDup(const char* str, int n) {
   return result;
 }
 
+
+#if !V8_HAS__ALIGNED_MALLOC && !V8_HAS_POSIX_MEMALIGN

[Benedikt Meurer, 2014/01/09 10:42:52]

This looks weird. Can't we inline these trivial functions below?

[Sven Panne, 2014/01/09 12:04:19]

I explicitly outlined them, and I actually think it makes things more readable
and follows the DRY principle. Otherwise it is a total casting & bit fiddling
mess. Well it already is, but... ;-) I would prefer to leave the helpers.

+static void* AlignPointer(void* ptr, size_t alignment) {
+  uintptr_t mask = uintptr_t(alignment) - 1;
+  uintptr_t aligned = (reinterpret_cast<uintptr_t>(ptr) + mask) & ~mask;
+  return reinterpret_cast<void*>(aligned);
+}
+
+
+// We store a pointer to the real start of the buffer just in front of the
+// aligned buffer our clients see.
+void*& BufferStart(void* ptr) {
+  return reinterpret_cast<void**>(ptr)[-1];
+}
+#endif
+
+
+void* AlignedMalloc(size_t size, size_t alignment) {
+  ASSERT(IsPowerOf2(alignment) && alignment >= V8_ALIGNOF(void*));  // NOLINT
+  void* ptr;
+#if V8_HAS__ALIGNED_MALLOC
+  ptr = _aligned_malloc(size, alignment);
+#elif V8_HAS_POSIX_MEMALIGN
+  if (posix_memalign(&ptr, alignment, size)) ptr = NULL;
+#else
+  void* buffer = malloc(size + sizeof(void*) + alignment - 1);  // NOLINT
+  ptr = AlignPointer(reinterpret_cast<void**>(buffer) + 1, alignment);
+  if (ptr != NULL) BufferStart(ptr) = buffer;
+#endif
+  if (ptr == NULL) FatalProcessOutOfMemory("AlignedMalloc");
+  return ptr;
+}
+
+
+void AlignedFree(void *ptr) {
+#if V8_HAS__ALIGNED_MALLOC
+  _aligned_free(ptr);
+#elif V8_HAS_POSIX_MEMALIGN
+  free(ptr);
+#else
+  if (ptr != NULL) free(BufferStart(ptr));
+#endif
+}
+
 } }  // namespace v8::internal