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Re: [RTL] Canonicalize commutative operations more

From: Jeff Law <law at redhat dot com>
To: Eric Botcazou <ebotcazou at adacore dot com>
Cc: Marc Glisse <marc dot glisse at inria dot fr>, gcc-patches at gcc dot gnu dot org
Date: Tue, 02 Apr 2013 09:29:43 -0600
Subject: Re: [RTL] Canonicalize commutative operations more
References: <alpine dot DEB dot 2 dot 02 dot 1303191715280 dot 4515 at stedding dot saclay dot inria dot fr> <1420303 dot Yr0JhII12W at polaris> <alpine dot DEB dot 2 dot 02 dot 1304021202300 dot 21244 at stedding dot saclay dot inria dot fr> <5990842 dot GuiiquCisS at polaris>

On 04/02/2013 04:54 AM, Eric Botcazou wrote:

I wonder if those issues might in most cases be bugs in the back-ends
(optimizations missed depending on the order), that the canonicalization
would make more noticable (and thus easier to fix).


There are certainly such issues in the back-ends (and even ??? comments about
it) so sensible canonicalization is desirable.

Right. The choice between canonicalization and code bloat to supportmultiple RTL forms computing the same value is a never-ending problem.Where it's clearly made sense we have canonicalized, where it doesn't,we haven't. There's a huge no-mans land in the middle.


Jeff

References:
- Re: [RTL] Canonicalize commutative operations more
  - From: Eric Botcazou
- Re: [RTL] Canonicalize commutative operations more
  - From: Marc Glisse
- Re: [RTL] Canonicalize commutative operations more
  - From: Eric Botcazou

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