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JJoseph Huber[libc] Rework match any use in hot allocate bitfield loop

a7649007创建于 2025年7月28日历史提交

文件	最后提交记录	最后更新时间
CMakeLists.txt	[libc] Efficiently implement aligned_alloc for AMDGPU (#146585) Summary: This patch uses the actual allocator interface to implement aligned_alloc. We do this by simply rounding up the amount allocated. Because of how index calculation works, any offset within an allocated pointer will still map to the same chunk, so we can just adjust internally and it will free all the same.	1 年前
aligned_alloc.cpp	[libc] Fix internal alignment in allcoator (#146738) Summary: The allocator interface is supposed to have 16 byte alignment (to keep it consistent with the CPU allocator. We could probably drop this to 8 if desires.) But this was not enforced because the number of bytes used for the bitfield sometimes resulted in alignment of 8 instead of 16. Explicitly align the number of bytes to be a multiple of 16 even if unused.	1 年前
malloc.cpp	[libc] Fix internal alignment in allcoator (#146738) Summary: The allocator interface is supposed to have 16 byte alignment (to keep it consistent with the CPU allocator. We could probably drop this to 8 if desires.) But this was not enforced because the number of bytes used for the bitfield sometimes resulted in alignment of 8 instead of 16. Explicitly align the number of bytes to be a multiple of 16 even if unused.	1 年前
malloc_stress.cpp	[libc] Rework match any use in hot allocate bitfield loop Summary: We previously used match_all as the shortcut to figure out which threads were destined for which slots. This lowers to a for-loop, which even if it often only executes once still causes some slowdown especially when divergent. Instead we use a single ballot call and then calculate it. Here the ballot tells us which lanes are the first in a block, either the starting index or the barrier for a new 32-bit int. We then use some bit magic to figure out for each lane ID its closest leader. For the length we simply use the length calculated by the leader of the remaining bits to be written. This removes the match any and the shuffle, which improves the minimum number of cycles this takes by about 5%.	1 年前
realloc.cpp	[libc] Efficiently implement 'realloc' for AMDGPU devices (#145960) Summary: Now that we have malloc we can implement realloc efficiently. This uses the known chunk sizes to avoid unnecessary allocations. We just return nullptr for NVPTX. I'd remove the list for the entrypoint but then the libc++ code would stop working. When someone writes the NVPTX support this will be trivial.	1 年前