MAINT: Refactor partial load workaround for Clang#24461
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charris merged 1 commit intonumpy:mainfrom Sep 5, 2023
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Clang exhibits aggressive optimization behavior when the `-ftrapping-math` flag is not fully supported, starting from -O1 optimization level. When partially loading a vector register for operations that require filling up the remaining lanes with specific values (e.g., divide operations needing non-zero integers to prevent FP exception divide-by-zero), Clang's optimizer recognizes that the full register is unnecessary for the store operation. Consequently, it optimizes out the fill step involving non-zero integers for the remaining elements. As a solution, we apply the `volatile` keyword to the returned register, followed by a symmetric operand operation like `or`, to inform the compiler about the necessity of the full vector. This refactor involves transferring this workaround from the source files to the universal intrinsic headers, also to guarantee that it is applied by all kernels. Furthermore, the workaround is disabled when the `-ftrapping-math` flag is fully supported by the Clang compiler. This patch also enables `-ftrapping-math` flag for clang-cl and suppress floating point exceptions warnings.
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Clang exhibits aggressive optimization behavior when the
-ftrapping-mathflag is not fully supported,starting from -O1 optimization level. When partially loading a vector register for operations that
require filling up the remaining lanes with specific values (e.g., divide operations needing non-zero
integers to prevent FP exception divide-by-zero), Clang's optimizer recognizes that the full register
is unnecessary for the store operation. Consequently, it optimizes out the fill step involving
non-zero integers for the remaining elements.
As a solution, we apply the
volatilekeyword to the returned vector, followed by a symmetricoperand operation like
or, to inform the compiler about the necessity of the full vector.This refactor involves transferring this workaround from the source files to the universal intrinsic headers,
also to guarantee that it is applied by all kernels. Furthermore, the workaround is disabled when the
-ftrapping-mathflag is fully supported by the Clang compiler.This patch also enables
-ftrapping-mathflag for clang-cl which is required to enabled SIMD optimization on operations such log/exp/sin/cos and suppress floating point exceptions warnings.