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Re: [PATCH] Reset or update VR during phiopt value_replacement (PR tree-optimization/65053)

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: Fri, 13 Feb 2015 15:51:43 -0700
Subject: Re: [PATCH] Reset or update VR during phiopt value_replacement (PR tree-optimization/65053)
Authentication-results: sourceware.org; auth=none
References: <20150213195201 dot GP1746 at tucnak dot redhat dot com>

On 02/13/15 12:52, Jakub Jelinek wrote:

Hi!

When moving assignment out of a conditional block before the condition, we
need to either reset or update SSA_NAME_RANGE_INFO, otherwise it might be
wrong, because when computed earlier, it could take into account that in
the conditional block the condition is or is not true.

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

2015-02-13  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/65053
	* tree-ssa-phiopt.c (value_replacement): When moving assign before
	cond, either reset VR on lhs or set it to phi result VR.

	* gcc.c-torture/execute/pr65053-1.c: New test.
	* gcc.c-torture/execute/pr65053-2.c: New test.

OK.

I wouldn't be terribly surprised if we have a variety of these kind ofbugs lurking. Basically everything which moves statements like thispotentially needs updating.


jeff

References:
- [PATCH] Reset or update VR during phiopt value_replacement (PR tree-optimization/65053)
  - From: Jakub Jelinek

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