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Split FreeWithHooksOrPerThread into per-thread and hooked free slow paths. #998

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Split FreeWithHooksOrPerThread into per-thread and hooked free slow paths. #998

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38 changes: 25 additions & 13 deletions tcmalloc/tcmalloc.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -572,16 +572,12 @@ inline SizeAndSampled GetSizeAndSampled(const void* ptr) {

inline size_t GetSize(const void* ptr) { return GetSizeAndSampled(ptr).size; }

// This slow path also handles delete hooks and non-per-cpu mode.
ABSL_ATTRIBUTE_NOINLINE static void FreeWithHooksOrPerThread(
void* ptr, std::optional<size_t> size, size_t size_class) {
MallocHook::InvokeDeleteHook({ptr, size,
tc_globals.sizemap().class_to_size(size_class),
HookMemoryMutable::kMutable});
if (ABSL_PREDICT_TRUE(UsePerCpuCache(tc_globals))) {
tc_globals.cpu_cache().DeallocateSlow(ptr, size_class);
} else if (ThreadCache* cache = ThreadCache::GetCacheIfPresent();
ABSL_PREDICT_TRUE(cache)) {
// This slow path handles non-per-cpu mode. It is kept out-of-line so that the
// per-CPU slow path does not carry the ThreadCache::Deallocate body.
ABSL_ATTRIBUTE_NOINLINE static void FreeSmallPerThread(void* ptr,
size_t size_class) {
if (ThreadCache* cache = ThreadCache::GetCacheIfPresent();
ABSL_PREDICT_TRUE(cache)) {
cache->Deallocate(ptr, size_class);
} else {
// This thread doesn't have thread-cache yet or already. Delete directly
Expand All @@ -591,6 +587,20 @@ ABSL_ATTRIBUTE_NOINLINE static void FreeWithHooksOrPerThread(
}
}

// This slow path also handles delete hooks.
ABSL_ATTRIBUTE_NOINLINE static void FreeSmallHooked(void* ptr,
std::optional<size_t> size,
size_t size_class) {
MallocHook::InvokeDeleteHook({ptr, size,
tc_globals.sizemap().class_to_size(size_class),
HookMemoryMutable::kMutable});
if (ABSL_PREDICT_TRUE(UsePerCpuCache(tc_globals))) {
tc_globals.cpu_cache().DeallocateSlow(ptr, size_class);
} else {
FreeSmallPerThread(ptr, size_class);
}
}

// In free fast-path we handle a number of conditions (delete hooks,
// full cpu cache, uncached per-cpu slab pointer, etc) by delegating work to
// slower function that handles all of these cases. This is done so that free
Expand All @@ -599,9 +609,11 @@ ABSL_ATTRIBUTE_NOINLINE static void FreeWithHooksOrPerThread(
ABSL_ATTRIBUTE_NOINLINE static void FreeSmallSlow(void* ptr,
std::optional<size_t> size,
size_t size_class) {
if (ABSL_PREDICT_FALSE(Static::HaveHooks()) ||
ABSL_PREDICT_FALSE(!UsePerCpuCache(tc_globals))) {
return FreeWithHooksOrPerThread(ptr, size, size_class);
if (ABSL_PREDICT_FALSE(Static::HaveHooks())) {
return FreeSmallHooked(ptr, size, size_class);
}
if (ABSL_PREDICT_FALSE(!UsePerCpuCache(tc_globals))) {
return FreeSmallPerThread(ptr, size_class);
}
TCMALLOC_ALWAYS_INLINE_CALL tc_globals.cpu_cache().DeallocateSlowNoHooks(
ptr, size_class);
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