This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug target/57819] Suboptimal shift patterns
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 04 Jul 2013 15:00:51 +0000
- Subject: [Bug target/57819] Suboptimal shift patterns
- Auto-submitted: auto-generated
- References: <bug-57819-4 at http dot gcc dot gnu dot org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57819
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 30457
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30457&action=edit
gcc49-pr57819-2.patch
Alternative that touches only i386 backend.
In theory I think the simplify-rtx.c and combine.c changes are good and
desirable, perhaps even with what I've tried first - that
(zero_extend:SI (subreg:QI (and:DI (reg:DI) (const_int 63)) 0))
would be folded into
(subreg:SI (and:DI (reg:DI) (const_int 63)) 0)
But perhaps many backends will be surprised by that change and will need tweaks
here and there. So any preferences here? I can bootstrap/regtest both
patches...