[libc] Use __builtin_elementwise_fma instead of __builtin_fma #126288
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__builtin_elementwise_fma doesn't consider errno and is thus more suitable for libc fma implementation. Fixes llvm#126025
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@llvm/pr-subscribers-libc Author: Petr Hosek (petrhosek) Changes__builtin_elementwise_fma doesn't consider errno and is thus more suitable for libc fma implementation. Fixes #126025 Full diff: https://github.com/llvm/llvm-project/pull/126288.diff 2 Files Affected:
diff --git a/libc/src/__support/FPUtil/FMA.h b/libc/src/__support/FPUtil/FMA.h
index 807d685239732e5..7b505d22c06b6ac 100644
--- a/libc/src/__support/FPUtil/FMA.h
+++ b/libc/src/__support/FPUtil/FMA.h
@@ -25,11 +25,11 @@ LIBC_INLINE OutType fma(InType x, InType y, InType z) {
#ifdef LIBC_TARGET_CPU_HAS_FMA
template <> LIBC_INLINE float fma(float x, float y, float z) {
- return __builtin_fmaf(x, y, z);
+ return __builtin_elementwise_fma(x, y, z);
}
template <> LIBC_INLINE double fma(double x, double y, double z) {
- return __builtin_fma(x, y, z);
+ return __builtin_elementwise_fma(x, y, z);
}
#endif // LIBC_TARGET_CPU_HAS_FMA
diff --git a/libc/src/__support/FPUtil/multiply_add.h b/libc/src/__support/FPUtil/multiply_add.h
index a86067c401873ba..763799f1f29d72b 100644
--- a/libc/src/__support/FPUtil/multiply_add.h
+++ b/libc/src/__support/FPUtil/multiply_add.h
@@ -47,11 +47,11 @@ namespace LIBC_NAMESPACE_DECL {
namespace fputil {
LIBC_INLINE float multiply_add(float x, float y, float z) {
- return __builtin_fmaf(x, y, z);
+ return __builtin_elementwise_fma(x, y, z);
}
LIBC_INLINE double multiply_add(double x, double y, double z) {
- return __builtin_fma(x, y, z);
+ return __builtin_elementwise_fma(x, y, z);
}
} // namespace fputil
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These are borrowed from OpenCL I believe and aren't available in gcc, so you'd need a has_builtin guard. https://godbolt.org/z/s63hK9Y4T.
They're supposed to support LLVM's vector type AFAIK. |
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✅ With the latest revision this PR passed the C/C++ code formatter. |
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I wonder if we should use the inline assembly version in the case where |
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I'm fine with that; at least for 32b ARM (wasn't that the only arch that was problematic?). |
…26288) __builtin_elementwise_fma doesn't consider errno and is thus more suitable for libc fma implementation.
…26288) __builtin_elementwise_fma doesn't consider errno and is thus more suitable for libc fma implementation.
__builtin_elementwise_fma doesn't consider errno and is thus more suitable for libc fma implementation.