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[Bug c/79973] atanh() constant-folds differently than it would evaluate at runtime
- From: "glisse at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 09 Mar 2017 09:23:04 +0000
- Subject: [Bug c/79973] atanh() constant-folds differently than it would evaluate at runtime
- Auto-submitted: auto-generated
- References: <bug-79973-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79973
--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
gcc computes the exact, correctly-rounded value, while at runtime you are using
code from some library (probably glibc) that trades off some precision for
speed. What would you like to happen? That gcc stops constant folding atanh?
You can do that with -fno-builtin-atanh. Or that glibc computes the correctly
rounded value? There are libraries out there that do that, but they are usually
quite a bit slower...