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Re: [RFA] Restore combine.c split point for multiply-accumulate instructions
- From: Jeff Law <law at redhat dot com>
- To: Segher Boessenkool <segher at kernel dot crashing dot org>
- Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 21 May 2015 07:51:41 -0600
- Subject: Re: [RFA] Restore combine.c split point for multiply-accumulate instructions
- Authentication-results: sourceware.org; auth=none
- References: <555D6F64 dot 3040300 at redhat dot com> <20150521134026 dot GA10871 at gate dot crashing dot org>
On 05/21/2015 07:40 AM, Segher Boessenkool wrote:
On Wed, May 20, 2015 at 11:38:44PM -0600, Jeff Law wrote:
I've also verified this is one of the changes ultimately necessary to
resolve the code generation regressions caused by Venkat's combine.c
change on the PA across my 300+ testfiles for a PA cross compiler.
How much does it help, do you know?
It resolves the remaining missed opportunities to create shadd insns
across those 300+ files.
There's one more combine.c patch on the way to canonicalize in one more
place -- which fixes a missed CSE due to a MULT in one context and
ASHIFT in another.
Then it's strictly cleanup on the PA port to kill the old MULT patterns.
It might be better to also check if it is shifting by a CONST_INT.
I doubt it matters much, but it is closer to the original.
Sure, that's not a problem at all. Will do after the usual testing.
jeff