MarkdownLog/UE5/内存/Malloc

FMalloc

FMallocAnsi

使用 FMallocAnsi 分配内存时，根据平台不同，调用不同平台的内存申请函数 _aligned_malloc、memalign、malloc

void* FMallocAnsi::TryMalloc(SIZE_T Size, uint32 Alignment)
{
#if !UE_BUILD_SHIPPING
	uint64 LocalMaxSingleAlloc = MaxSingleAlloc.Load(EMemoryOrder::Relaxed);
	if (LocalMaxSingleAlloc != 0 && Size > LocalMaxSingleAlloc)
	{
		return nullptr;
	}
#endif

	Alignment = FMath::Max(Size >= 16 ? (uint32)16 : (uint32)8, Alignment);

	void* Result = AnsiMalloc(Size, Alignment);

	return Result;
}

void* AnsiMalloc(SIZE_T Size, uint32 Alignment)
{
#if PLATFORM_USES__ALIGNED_MALLOC
	void* Result = _aligned_malloc( Size, Alignment );
#elif PLATFORM_USE_ANSI_POSIX_MALLOC
	void* Result;
	if (UNLIKELY(posix_memalign(&Result, Alignment, Size) != 0))
	{
		Result = nullptr;
	}
#elif PLATFORM_USE_ANSI_MEMALIGN
	void* Result = memalign(Alignment, Size);
#else
	void* Ptr = malloc(Size + Alignment + sizeof(void*) + sizeof(SIZE_T));
	void* Result = nullptr;
	if (Ptr)
	{
		Result = Align((uint8*)Ptr + sizeof(void*) + sizeof(SIZE_T), Alignment);
		 *((void**)((uint8*)Result - sizeof(void*))) = Ptr;
		*((SIZE_T*)((uint8*)Result - sizeof(void*) - sizeof(SIZE_T))) = Size;
	}
#endif

	return Result;
}

释放内存也是，根据平台不同调用不同的释放函数 _aligned_free、free

void AnsiFree(void* Ptr)
{
#if PLATFORM_USES__ALIGNED_MALLOC
	_aligned_free(Ptr);
#elif PLATFORM_USE_ANSI_POSIX_MALLOC || PLATFORM_USE_ANSI_MEMALIGN
	free(Ptr);
#else
	if (Ptr)
	{
		free(*((void**)((uint8*)Ptr - sizeof(void*))));
	}
#endif
}

FMallocBinned