[libc-commits] [PATCH] D124495: [libc] Implement double precision FMA for targets without FMA instructions.
Tue Ly via Phabricator via libc-commits
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Wed Apr 27 19:24:46 PDT 2022
lntue added inline comments.
Comment at: libc/test/src/math/fma_no_fma_test.cpp:10
> You should be able to include `generic/FMA.h` directly and avoid this?
The main point was to test that `__llvm_libc::fma` implementation works correctly without `LIBC_TARGET_HAS_FMA`. Unfortunately `src.math.fma` is an object target built with just 1 config (FMA flag on our machine) so I choose to inlining its implementation here, which is simply calling `__llvm_libc::fputil::fma`, regardless of FMA flags. If we include `generic/FMA.h` directly, we wouldn't know/test directly if the `fma` implementation in `generic/FMA.h` is called or `__llvm_libc::fputil::fma` works correctly without FMA flag, unless we run it on non-FMA machines.
I guess we could instrument the build system to do these, but I'm not sure if it could be cleaner, especially when the behaviors of such functions with or without FMA diverge.
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