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Re: PR64454: (x % y) % y

From: Jeff Law <law at redhat dot com>
To: Marc Glisse <marc dot glisse at inria dot fr>, gcc-patches at gcc dot gnu dot org
Date: Thu, 14 May 2015 11:44:18 -0600
Subject: Re: PR64454: (x % y) % y
Authentication-results: sourceware.org; auth=none
References: <alpine dot DEB dot 2 dot 02 dot 1505141801110 dot 4707 at stedding dot saclay dot inria dot fr>

On 05/14/2015 10:33 AM, Marc Glisse wrote:

Hello,

after this patch I think I'll close the PR. This was regtested on
ppc64le-redhat-linux.

Apparently I wrote this patch in a file that already had a trivial hunk:
-1-A -> ~A is rejected for complex while -A-1 isn't, there is no reason
for this difference (maybe there was before integer_all_onesp /
integer_minus_onep was introduced), I hope you don't mind.

I am wondering if we want some helper (like :c for commutative
operations) to avoid duplicating patterns for x<y and y>x. We could
also, when a comparison x<=y doesn't simplify, see if !!(x<=y)
simplifies better, but that's becoming a bit complicated.

2015-05-15  Marc Glisse  <marc.glisse@inria.fr>

     PR tree-optimization/64454
gcc/
     * match.pd ((X % Y) % Y, (X % Y) < Y): New patterns.
     (-1 - A -> ~A): Remove unnecessary condition.
gcc/testsuite/
     * gcc.dg/modmod.c: New testcase.

OK.
jeff

References:
- PR64454: (x % y) % y
  - From: Marc Glisse

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