[llvm] Simplify hot-path size computations in BumpPtrAllocator. (PR #101467)
via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 1 03:02:42 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-support
Author: Owen Anderson (resistor)
<details>
<summary>Changes</summary>
~0.1% instruction count improvements
https://llvm-compile-time-tracker.com/compare.php?from=07d2709a17860a202d91781769a88837e4fb5f2a&to=d5cc47831ecd9f0a2b164b16da67f74b94e9aafc&stat=instructions:u
---
Full diff: https://github.com/llvm/llvm-project/pull/101467.diff
1 Files Affected:
- (modified) llvm/include/llvm/Support/Allocator.h (+10-8)
``````````diff
diff --git a/llvm/include/llvm/Support/Allocator.h b/llvm/include/llvm/Support/Allocator.h
index e05f0ec0e8704..568f0d34032fa 100644
--- a/llvm/include/llvm/Support/Allocator.h
+++ b/llvm/include/llvm/Support/Allocator.h
@@ -149,8 +149,7 @@ class BumpPtrAllocatorImpl
// Keep track of how many bytes we've allocated.
BytesAllocated += Size;
- size_t Adjustment = offsetToAlignedAddr(CurPtr, Alignment);
- assert(Adjustment + Size >= Size && "Adjustment + Size must not overflow");
+ uintptr_t AlignedPtr = alignAddr(CurPtr, Alignment);
size_t SizeToAllocate = Size;
#if LLVM_ADDRESS_SANITIZER_BUILD
@@ -158,19 +157,22 @@ class BumpPtrAllocatorImpl
SizeToAllocate += RedZoneSize;
#endif
+ uintptr_t AllocEndPtr = AlignedPtr + SizeToAllocate;
+ assert(AllocEndPtr >= uintptr_t(CurPtr) &&
+ "Alignment + Size must not overflow");
+
// Check if we have enough space.
- if (LLVM_LIKELY(Adjustment + SizeToAllocate <= size_t(End - CurPtr)
+ if (LLVM_LIKELY(AllocEndPtr <= uintptr_t(End)
// We can't return nullptr even for a zero-sized allocation!
&& CurPtr != nullptr)) {
- char *AlignedPtr = CurPtr + Adjustment;
- CurPtr = AlignedPtr + SizeToAllocate;
+ CurPtr = reinterpret_cast<char *>(AllocEndPtr);
// Update the allocation point of this memory block in MemorySanitizer.
// Without this, MemorySanitizer messages for values originated from here
// will point to the allocation of the entire slab.
- __msan_allocated_memory(AlignedPtr, Size);
+ __msan_allocated_memory(reinterpret_cast<char *>(AlignedPtr), Size);
// Similarly, tell ASan about this space.
- __asan_unpoison_memory_region(AlignedPtr, Size);
- return AlignedPtr;
+ __asan_unpoison_memory_region(reinterpret_cast<char *>(AlignedPtr), Size);
+ return reinterpret_cast<char *>(AlignedPtr);
}
return AllocateSlow(Size, SizeToAllocate, Alignment);
``````````
</details>
https://github.com/llvm/llvm-project/pull/101467
More information about the llvm-commits
mailing list