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Re: PR 23046. Folding predicates involving TYPE_MAX_VALUE/TYPE_MIN_VA

From: Robert Dewar <dewar at adacore dot com>
To: Mike Stump <mrs at apple dot com>
Cc: Laurent GUERBY <laurent at guerby dot net>, Kai Henningsen <kaih at khms dot westfalen dot de>, gcc at gcc dot gnu dot org
Date: Sat, 13 Aug 2005 07:24:33 -0400
Subject: Re: PR 23046. Folding predicates involving TYPE_MAX_VALUE/TYPE_MIN_VA
References: <10508121750.AA15217@vlsi1.ultra.nyu.edu> <9bhwbzTXw-B@khms.westfalen.de> <1123886705.7742.5.camel@pc.site> <EED4BFCC-50A7-4D9B-B884-FBFC558DFEFE@apple.com>

Mike Stump wrote:

On Aug 12, 2005, at 3:45 PM, Laurent GUERBY wrote:

Isn't it possible to attach some information on a comparison
statement that tells code generation never to never
optimize away this particular comparison even if it
seems to be able to prove it is always true or false?

Cough, hack, ick.


i really think the better hack is one that says
do not propagate type range info through a
conversion, or perhaps says "drop any information you think
you have deduced about the range of this expression, if
either

a) that info comes from type range analysis

or

b) u do not know where it came from

References:
- Re: PR 23046. Folding predicates involving TYPE_MAX_VALUE/TYPE_MIN_VALUE (Ada RFC)
  - From: Richard Kenner
- Re: PR 23046. Folding predicates involving TYPE_MAX_VALUE/TYPE_MIN_VA
  - From: Kai Henningsen
- Re: PR 23046. Folding predicates involvingTYPE_MAX_VALUE/TYPE_MIN_VA
  - From: Laurent GUERBY
- Re: PR 23046. Folding predicates involving TYPE_MAX_VALUE/TYPE_MIN_VA
  - From: Mike Stump

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