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[Bug middle-end/79665] gcc's signed (x*x)/200 is slower than clang's
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 23 Feb 2017 09:41:24 +0000
- Subject: [Bug middle-end/79665] gcc's signed (x*x)/200 is slower than clang's
- Auto-submitted: auto-generated
- References: <bug-79665-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79665
--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
You can put a breakpoint at the new expr.c code and see what both the unsigned
and signed sequences are and see what seq_cost gcc computed. If the costs
don't match the hw, then it can of course choose a worse sequence.