This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug rtl-optimization/50088] movzbl is generated instead of movl
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 15 Aug 2011 15:26:19 +0000
- Subject: [Bug rtl-optimization/50088] movzbl is generated instead of movl
- Auto-submitted: auto-generated
- References: <bug-50088-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50088
--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-08-15 15:26:19 UTC ---
(In reply to comment #3)
> It is done on purpose:
>
> /* X86_TUNE_MOVX: Enable to zero extend integer registers to avoid
> partial dependencies. */
> m_PPRO | m_P4_NOCONA | m_CORE2I7 | m_ATOM | m_GEODE | m_AMD_MULTIPLE |
> m_GENERIC,
>
> You can remove m_ATOM to see its performance impact with -mtune=atom
> on Atom.
Well, yes, I think the proposal was to spill/load the full SImode instead
which would avoid both the partial dependency and the mismatched load/store
size. No?