llvmorg-github-actions[bot] wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Piotr Kubaj (pkubaj)
<details>
<summary>Changes</summary>
The big-endian vbpermq permute constant in the ppc_wrappers
_mm_movemask_ps lists the four sign-bit indices as 0x00 0x20 0x40 0x60,
which lands element 0 in the most significant of the four result bits.
x86 semantics (and the little-endian branch) put element 0 in bit 0.
Reverse the index order so big-endian returns the same mask as x86.
Verified on FreeBSD/powerpc64 (POWER9, -mcpu=power8): for the inputs
{-1,2,-3,4} and {1,2,3,-4} the header returned 10 and 1 instead of 5
and 8; embree's BVH traversal, which selects child nodes from this
mask, crashed with a wild pointer. _mm_movemask_pd and
_mm_movemask_epi8 already produce x86-compatible results on both
endians.
Assisted-by: Claude Fable 5.1
---
Full diff: https://github.com/llvm/llvm-project/pull/224328.diff
1 Files Affected:
- (modified) clang/lib/Headers/ppc_wrappers/xmmintrin.h (+1-1)
``````````diff
diff --git a/clang/lib/Headers/ppc_wrappers/xmmintrin.h
b/clang/lib/Headers/ppc_wrappers/xmmintrin.h
index 9dd21b65c2f70..96a309be25b29 100644
--- a/clang/lib/Headers/ppc_wrappers/xmmintrin.h
+++ b/clang/lib/Headers/ppc_wrappers/xmmintrin.h
@@ -1318,7 +1318,7 @@ extern __inline int
#ifdef __LITTLE_ENDIAN__
0x00204060, 0x80808080, 0x80808080, 0x80808080
#else
- 0x80808080, 0x80808080, 0x80808080, 0x00204060
+ 0x80808080, 0x80808080, 0x80808080, 0x60402000
#endif
};
``````````
</details>
https://github.com/llvm/llvm-project/pull/224328
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