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Re: [RFA][PATCH][pr target/60648] Fix non-canonical RTL from x86 backend -- P1 regression
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Jeff Law <law at redhat dot com>
- Cc: Richard Henderson <rth at redhat dot com>, Uros Bizjak <ubizjak at gmail dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 26 Mar 2014 20:40:05 +0100
- Subject: Re: [RFA][PATCH][pr target/60648] Fix non-canonical RTL from x86 backend -- P1 regression
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- References: <53330838 dot 7010402 at redhat dot com> <20140326181259 dot GK1817 at tucnak dot redhat dot com> <533319C7 dot 5060201 at redhat dot com> <20140326182808 dot GM1817 at tucnak dot redhat dot com> <53332B5C dot 9030409 at redhat dot com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Wed, Mar 26, 2014 at 01:32:44PM -0600, Jeff Law wrote:
> On 03/26/14 12:28, Jakub Jelinek wrote:
> >(mult:SI (const_int 0) (const_int 4)) is IMHO far from being canonical.
> >And, I'd say it is likely other target legitimization hooks would also try
> >to simplify it similarly.
> >simplify_gen_binary is used in several other places during expansion,
> >so I don't see why it couldn't be desirable here.
> No particular reason. I'll try that since we disagree about the
> validity of the RTL and we can both agree that using
> simplify_gen_binary is reasonable.
Other possibility if you want to change it in the i386.c legitimize_address
hook would be IMHO using force_reg instead of force_operand, it should be
the same thing in most cases, except for these corner cases, and there would
be no need to canonizalize anything afterwards.
But, if the i?86 maintainers feel otherwise on this and think your patch is
ok, I don't feel that strongly about this.
Jakub