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Re: [PATCH] i386: Do not modify existing RTL (PR66412)

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: Wed, 24 Jun 2015 21:42:24 -0600
Subject: Re: [PATCH] i386: Do not modify existing RTL (PR66412)
Authentication-results: sourceware.org; auth=none
References: <1435188550-12345-1-git-send-email-segher at kernel dot crashing dot org> <558B782C dot 90105 at redhat dot com>

On 06/24/2015 09:40 PM, Jeff Law wrote:

On 06/24/2015 05:29 PM, Segher Boessenkool wrote:

A few define_split's in the i386 backend modify RTL in place.  This does
not work.  This patch fixes all cases that do PUT_MODE on existing RTL.

Bootstrapped and tested; no regressions.  Is this okay for trunk?

Hrm, this wants the testcase in that PR added I suppose.  Will send
it separately.


Segher


2015-06-24  Segher Boessenkool  <segher@kernel.crashing.org>

    * config/i386/i386.md (various splitters): Use copy_rtx before
    doing PUT_MODE on operands.

Are the copies really needed?  If we're slamming a mode into an
ix86_comparison_operator, we should be safe since those can't be shared.
  Copying is just wasteful.

It might be worth verifying that something else hasn't created sharedRTL in violation of the RTL sharing assumptions.


Jeff

References:
- [PATCH] i386: Do not modify existing RTL (PR66412)
  - From: Segher Boessenkool
- Re: [PATCH] i386: Do not modify existing RTL (PR66412)
  - From: Jeff Law

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