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Re: Overflow problem in loop
- To: Andreas Schwab <schwab at issan dot informatik dot uni-dortmund dot de>
- Subject: Re: Overflow problem in loop
- From: Jeffrey A Law <law at upchuck dot cygnus dot com>
- Date: Sun, 04 Apr 1999 00:33:35 -0700
- cc: egcs-patches at egcs dot cygnus dot com
- Reply-To: law at cygnus dot com
In message <vyzd82b6qzg.fsf@issan.cs.uni-dortmund.de>you write:
> gcc.c-torture/execute/loop-2b.c triggers an overflow bug in loop. It
> tries to replace (INT_MAX-1) by (INT_MAX-1) * 4 + reg, which is obviously
> invalid.
>
>
> 1999-03-14 Andreas Schwab <schwab@issan.cs.uni-dortmund.de>
>
> * loop.c (maybe_eliminate_biv_1): Disable the remaining biv
> elimination inside comparison.
That (and some of the other) loop tests were written to test highly obscure
bugs in the loop optimizer -- often after looking at the loop.c sources.
I'd prefer not to disable strength-reduction to fix purely artificial
tests. If there's real code that is failing because of this bug, but
if there isn't I'd prefer not to.
jeff