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Re: [PATCH][AArch64] Handle -|x| case using a single csneg
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Kyrill Tkachov <kyrylo dot tkachov at arm dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, Marcus Shawcroft <Marcus dot Shawcroft at arm dot com>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>, James Greenhalgh <James dot Greenhalgh at arm dot com>
- Date: Tue, 14 Jul 2015 07:55:42 -0500
- Subject: Re: [PATCH][AArch64] Handle -|x| case using a single csneg
- Authentication-results: sourceware.org; auth=none
- References: <55A38963 dot 6080408 at arm dot com> <20150714003800 dot GA17453 at gate dot crashing dot org> <55A4C5BE dot 4070602 at arm dot com>
On Tue, Jul 14, 2015 at 09:18:06AM +0100, Kyrill Tkachov wrote:
> >Before combine, you have two insns, a negation and an abs, so that is
> >not so very strange :-)
Oh, hrm, my aarch64 cross was three months old, and this now changed.
Or I messed up. Sorry for the noise.
It does look like the if_then_else stuff in combine (and simplify-rtx)
could use some improvement, probably more than just fixing this one
case. Or look at the first huge case in combine_simplify_rtx, that
looks eerily similar.
Segher