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[Bug c++/54130] Recognize builtins with bool return type
- 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: Wed, 01 Aug 2012 09:49:12 +0000
- Subject: [Bug c++/54130] Recognize builtins with bool return type
- Auto-submitted: auto-generated
- References: <bug-54130-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54130
--- Comment #12 from Marc Glisse <glisse at gcc dot gnu.org> 2012-08-01 09:49:12 UTC ---
(In reply to comment #10)
> (In reply to comment #9)
> > I realize that several (not all) of the things discussed here assume that
> > functions returning bool and int are binary compatible, which is likely true on
> > most platforms but there might be exceptions.
>
> It's not true on x86_64 - return values are not extended to word_mode thus
> you may have garbage in the upper parts of %eax for bool.
Ok thanks, that seems to put the nail in the coffin for these techniques. I
guess I should close this bug, and file the only part that remains (the missed
optimization at the end of Comment 8) separately.