On Thu, Apr 26, 2012 at 5:28 PM, Jakub Jelinek <ja...@redhat.com> wrote:
>> > We have a splitter for reg1 = reg2 & 0xffffffff, but only if regnums >> > are different. But movl %edi, %edi is a cheaper variant of >> > andq $0xffffffff, %rdi even with the same register and doesn't clobber >> > flags, so this patch attempts to expand it as a zero extension early. >> > >> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? >> > >> > 2012-04-25 Jakub Jelinek <ja...@redhat.com> >> > >> > PR target/53110 >> > * config/i386/i386.md (and<mode>3): For andq $0xffffffff, reg >> > instead expand it as zero extension. >> >> Perhaps we can go all the way and also convert ANDs with $0xff and >> $0xffff to relevant zero_extend patterns, like in the referred >> splitter. > > I wasn't sure about 0xffff, on which CPUs it would be a win and on which it > would not. 0xffffffff is a win always. My recent changes to zero_extend expanders should handle this automatically, and will undo generation of zero_extend pattern. Please see zero_extend<mode>si2_and expander, and how it handles TARGET_ZERO_EXTEND_WITH_AND targets. Uros.
