This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug rtl-optimization/82692] [8 Regression] Ordered comparisons used for unordered built-ins
- From: "segher at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 25 Oct 2017 22:22:23 +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 #17 from Segher Boessenkool <segher at gcc dot gnu.org> ---
So we have a compare:CCFPU, the resulting flags is used in a GE
only, and ix86_cc_mode thinks the best mode to use for that is CCFP.
Which is fine, except compare:CCFPU is a different instruction, and GE
for the resulting insn means a different thing?!
How is this supposed to work? How can generic code know this?
Everything worked fine, except the compare insn did not do the side
effect of setting a status flag. Perhaps an unspec (or even an
unspec_volatile) should have been used for the compare?