This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]
Other format:	[Raw text]

Re: More type narrowing in match.pd

From: Jeff Law <law at redhat dot com>
To: Richard Biener <richard dot guenther at gmail dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
Date: Fri, 01 May 2015 12:57:45 -0600
Subject: Re: More type narrowing in match.pd
Authentication-results: sourceware.org; auth=none
References: <5541A704 dot 3070502 at redhat dot com> <CAFiYyc2u-zSP_DErk73ZEUXOgLfeT3NGa+fiA6uu5JxWFZjurg at mail dot gmail dot com> <alpine dot DEB dot 2 dot 11 dot 1504301247330 dot 9338 at stedding dot saclay dot inria dot fr> <CAFiYyc3q1Lw4t3sL82y9HJuPnrd5j9fkAnex0Ycqj5LhtCU36A at mail dot gmail dot com>

On 04/30/2015 05:07 AM, Richard Biener wrote:

On Thu, Apr 30, 2015 at 12:53 PM, Marc Glisse <marc.glisse@inria.fr> wrote:

On Thu, 30 Apr 2015, Richard Biener wrote:

I have in my local dev tree (so completely untested...)

@@ -1040,31 +1052,22 @@ (define_operator_list CBRT BUILT_IN_CBRT
    operation and convert the result to the desired type.  */
(for op (plus minus)
   (simplify
-    (convert (op (convert@2 @0) (convert@3 @1)))
+    (convert (op:c@4 (convert@2 @0) (convert?@3 @1)))



I believe the :c here requires extra code further down, so we don't turn a-b
into b-a.


Indeed.  I've added :c only for minus as 5 - x can't be canonicalized to
move the constant to 2nd position which is always possible for plus.

Might be cleaner to add a separate pattern for that case.

FWIW, this is the patch that's attached to 65084 (not 47477 as Iinitially reported). It's supposed to address one or more of theexample loops in that testcase.


I'd like to tackle it as a follow-up.
jeff

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]