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Re: [PATCH] Fix rtl sharing issue in RTL loop unroller (PR rtl-optimization/80500)

From: Jeff Law <law at redhat dot com>
To: Jakub Jelinek <jakub at redhat dot com>, Richard Biener <rguenther at suse dot de>
Cc: gcc-patches at gcc dot gnu dot org
Date: Mon, 24 Apr 2017 15:28:13 -0600
Subject: Re: [PATCH] Fix rtl sharing issue in RTL loop unroller (PR rtl-optimization/80500)
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References: <20170424211328.GQ1809@tucnak>

On 04/24/2017 03:13 PM, Jakub Jelinek wrote:

Hi!

The following testcase ICEs, because ve->reg is a SUBREG and thus should not
be shared, but we initialize sum to ve->reg, then add to it some REGs (which
can be shared always), and finally assign the addition etc. result into
ve->reg.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2017-04-24  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/80500
	* loop-unroll.c (combine_var_copies_in_loop_exit): Call copy_rtx on
	sum's initial value.

	* gcc.dg/pr80500.c: New test.

OK with some kind of comment indicating why we need to do the copy.

Jeff

References:
- [PATCH] Fix rtl sharing issue in RTL loop unroller (PR rtl-optimization/80500)
  - From: Jakub Jelinek

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