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[Bug rtl-optimization/75964] insn combiner removes comparison after ABS
- From: "ebotcazou 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 Feb 2017 11:09:20 +0000
- Subject: [Bug rtl-optimization/75964] insn combiner removes comparison after ABS
- Auto-submitted: auto-generated
- References: <bug-75964-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=75964
Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |ebotcazou at gcc dot gnu.org
--- Comment #1 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> After pass .combine, the 2nd comparison is missing, presumably because
> combiner invokes signed overflow on ABS which does not apply because all
> computations are performed as unsigned.
Then you should have a warning with -Wstrict-overflow; this possibly comes from
simplify-rtx.c:simplify_const_relational_operation in this case.