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Re: PATCH: PR target/39942: Nonoptimal code - leaveq; xchg %ax,%ax; retq
- From: Jakub Jelinek <jakub at redhat dot com>
- To: "H.J. Lu" <hongjiu dot lu at intel dot com>
- Cc: gcc-patches at gcc dot gnu dot org, ubizjak at gmail dot com
- Date: Fri, 15 May 2009 16:34:45 +0200
- Subject: Re: PATCH: PR target/39942: Nonoptimal code - leaveq; xchg %ax,%ax; retq
- References: <20090515140821.GA28751@lucon.org>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Fri, May 15, 2009 at 07:08:21AM -0700, H.J. Lu wrote:
> ix86_avoid_jump_misspredicts use "align" pattern to pad to a 16byte
> boundary. "align" pattern uses ASM_OUTPUT_MAX_SKIP_ALIGN. For Linux,
> it
See my http://gcc.gnu.org/ml/gcc-patches/2009-05/msg00702.html
patch, I think ASM_OUTPUT_MAX_SKIP_ALIGN should be fixed anyway
to not do the extra .p2align 3 if MAX_SKIP is less than 7.
ASM_OUTPUT_MAX_SKIP_PAD doesn't hurt, though I think it only rarely
will make a difference. Anyway, I think it makes no sense to require
it duplicated in all the headers, just define the new macro
in linux.h and x86-64.h and in i386.md just use ASM_OUTPUT_MAX_SKIP_PAD
if it exists, otherwise fall back to ASM_OUTPUT_MAX_SKIP_ALIGN.
Jakub