Re: optimization/6822: GCC 3.1.1 - Internal compiler error in extract_insn, at recog.c:2132

[Glen Nakamura <glen@imodulo.com>]

The following reply was made to PR optimization/6822; it has been noted by GNATS.

From: Glen Nakamura <glen@imodulo.com>
To: gcc-gnats@gcc.gnu.org, gcc-bugs@gcc.gnu.org
Cc:  
Subject: Re: optimization/6822: GCC 3.1.1 - Internal compiler error in extract_insn, at recog.c:2132
Date: Tue, 28 May 2002 03:54:54 -1000

 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6822
 
 I believe the following patch is the cause of this PR:
 
 2002-05-15  Eric Botcazou  <ebotcazou@multimania.com>
 
 	* fold-const.c (fold) [LT_EXPR]: Move the transformation of a
 	comparison against the highest or lowest integer value before
 	the 'X >= CST to X > (CST - 1)' and 'X < CST to X <= (CST - 1)'
 	transformation and that of an unsigned comparison against 0
 	right after.
 
 Previously, unsigned X < 128 would be converted to unsigned X <= 127 and
 then optimized to signed X >= 0.  After changing the order of the
 transformations, the compiler only reduces the expression to X <= 127 ???
 The result is the reported ICE.  This could very well be a latent bug
 in other parts of the compiler, but it seems the change results in missed
 opportunities to simplify expressions.  I'll post an alternative patch
 in my next message...
 
 - Glen Nakamura