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Re: [PATCH 3/6] combine: handle I2 a parallel of two SETs

From: Jeff Law <law at redhat dot com>
To: Segher Boessenkool <segher at kernel dot crashing dot org>, gcc-patches at gcc dot gnu dot org
Date: Mon, 01 Dec 2014 10:43:50 -0700
Subject: Re: [PATCH 3/6] combine: handle I2 a parallel of two SETs
Authentication-results: sourceware.org; auth=none
References: <cover dot 1417135737 dot git dot segher at kernel dot crashing dot org> <9c173bc0a5f174717ca93b7263231f63631c65a7 dot 1417135737 dot git dot segher at kernel dot crashing dot org>

On 11/27/14 18:44, Segher Boessenkool wrote:

If I2 is a PARALLEL of two SETs, split it into two instructions, I1
and I2.  If there already was an I1, rename it to I0.  If there
already was an I0, don't do anything.

This surprisingly simple patch is enough to let combine handle such
PARALLELs properly.

v2: Add some functions to make the checking for a suitable PARALLEL
more readable (and more general).


2014-11-27  Segher Boessenkool  <segher@kernel.crashing.org>

gcc/
	* combine.c (is_parallel_of_n_reg_sets): New function.
	(can_split_parallel_of_n_reg_sets): New function.
	(try_combine): If I2 is a PARALLEL of two SETs, split it into
	two insns if possible.

OK. Please follow-up with a testcase showing the result of this work.PPC specific is fine, of course. Your call whether or not to test thedump file or assembly output.



jeff

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