[libc-commits] [PATCH] D115347: [libc] Use intrinsics for x86-64 fma and optimize PolyEval for x86-64 with degree 3 & 5 polynomials.

Tue Ly via Phabricator via libc-commits libc-commits at lists.llvm.org
Thu Dec 9 14:50:59 PST 2021

lntue marked an inline comment as done.
lntue added inline comments.

Comment at: libc/test/src/math/expm1f_test.cpp:111
-    ASSERT_MPFR_MATCH(mpfr::Operation::Expm1, x, __llvm_libc::expm1f(x), 1.5);
+    ASSERT_MPFR_MATCH(mpfr::Operation::Expm1, x, __llvm_libc::expm1f(x), 2.2);
sivachandra wrote:
> lntue wrote:
> > sivachandra wrote:
> > > If there is a possibility of trading off between performance and accuracy, we should provide build time switches for users to pick one or the other based on their needs. By default we want to "err" on the side of providing more accurate implementations over providing faster but less accurate implementations.
> > We're going to have a correctly rounded version for expm1f soon so I'm not worried about this regression yet.
> Do we know why the accuracy dropped? If yes, can we add the reason to the commit description?
Added a possible reason to the patch's summary.

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