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Re: [PATCH] Fix simplify_shift_const_1 once more (PR rtl-optimization/70429)
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 29 Mar 2016 12:36:52 -0500
- Subject: Re: [PATCH] Fix simplify_shift_const_1 once more (PR rtl-optimization/70429)
- Authentication-results: sourceware.org; auth=none
- References: <20160329172129 dot GO3017 at tucnak dot redhat dot com>
On Tue, Mar 29, 2016 at 07:21:29PM +0200, Jakub Jelinek wrote:
> This is a case similar to the LSHIFTRT I've fixed recently.
> But, unlike LSHIFTRT, which can be handled by masking at the outer level,
> ASHIFTRT would need outer sign extension, so most of the time 2 outer
> operations in addition to the kept two inner shifts, which is IMHO very
> unlikely to ever be successfully combined on any target nor actually
> beneficial. So this patch just avoids that optimization for ASHIFTRT
> if there are different modes.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Okay with spello fixed ("queuing"). Thanks,
Segher