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[Bug rtl-optimization/82692] [8 Regression] Ordered comparisons used for unordered built-ins
- From: "ubizjak at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 24 Oct 2017 19:32:07 +0000
- Subject: [Bug rtl-optimization/82692] [8 Regression] Ordered comparisons used for unordered built-ins
- Auto-submitted: auto-generated
- References: <bug-82692-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82692
--- Comment #9 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Segher Boessenkool from comment #8)
> Maybe you can handle this in can_change_dest_mode? That will catch
> the similar cases, too.
No, because we only have to prevent CCmode changes that apply to FP operands.
can_change_dest_mode only looks at mode changes, but CCFPmode and CCFPUmode are
x86 specific.
I have looked at other SELECT_CC_MODE changes, and they deal with propagation
of compares into arithmetic operations. This is the only place that can change
CCmode of FP compares.