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Re: [PR87874] avoid const-wide-int subreg in LRA

From: Vladimir Makarov <vmakarov at redhat dot com>
To: Alexandre Oliva <aoliva at redhat dot com>
Cc: gcc-patches at gcc dot gnu dot org
Date: Tue, 6 Nov 2018 14:45:59 -0500
Subject: Re: [PR87874] avoid const-wide-int subreg in LRA
References: <ork1lq4kcb.fsf@lxoliva.fsfla.org>

On 11/06/2018 04:38 AM, Alexandre Oliva wrote:

Just like CONST_INT, CONST_WIDE_INT is VOIDmode, so LRA might be
tempted to build a SUBREG to "convert" it to the wanted mode.  That's
no use.  Test for CONST_SCALAR_INT_P instead of CONST_INT_P so that we
skip the subreg creation for both.

Regstrapped on x86_64- and i686-linux-gnu.  Ok to install?

Yes.  Thank you, Alex.

for  gcc/ChangeLog

	PR rtl-optimization/87874
	* lra.c (lra_substitute_pseudo): Do not create a subreg for
	const wide ints.

for  gcc/testsuite/ChangeLog

	PR rtl-optimization/87874
	* gcc.dg/pr87874.c: New.

References:
- [PR87874] avoid const-wide-int subreg in LRA
  - From: Alexandre Oliva

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