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Re: does the instruction combiner regards (foo & 0xff) as a special case?

From: James E Wilson <wilson at specifix dot com>
To: ibanez at sunplus dot com
Cc: gcc at gcc dot gnu dot org
Date: Tue, 02 Aug 2005 10:45:28 -0700
Subject: Re: does the instruction combiner regards (foo & 0xff) as a special case?
References: <OFFC9AF895.C064E255-ON48257050.002E9628-48257050.002E965A@sunplus.com>

ibanez@sunplus.com wrote:

I guess the combiner generates something like
a trucation pattern when special constant are detected.
The combiner also takse a similiar action in pattern

See the section of the documentation that talks about instruction canonicalization. http://gcc.gnu.org/onlinedocs/gccint/Insn-Canonicalizations.html See in particular the last bullet.

Also, as Joern mentioned, you should try stepping through try_combine to see what is really happening. -- Jim Wilson, GNU Tools Support, http://www.specifix.com

References:
- Re: does the instruction combiner regards (foo & 0xff) as a special case?
  - From: ibanez

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