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Re: -funsafe-loop-optimizations

From: Daniel Berlin <dberlin at dberlin dot org>
To: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
Cc: gcc at gcc dot gnu dot org, dje at gcc dot gnu dot org
Date: Fri, 31 Dec 2004 16:50:12 -0500 (EST)
Subject: Re: -funsafe-loop-optimizations
References: <20041231211409.GA22814@atrey.karlin.mff.cuni.cz>

On Fri, 31 Dec 2004, Zdenek Dvorak wrote:

Hello,

several times some people sounded opinion that in addition to improving
analyses in loop optimizer, we might also add a flag that would enable
the compiler to assume that the compiled code does not contain loops
behaving in "weird" way (loops whose control induction variables
overflows, infinite loops with nontrivial exit conditions).

Almost all compilers i know of turn this on by default at -O2 or higher. So if we do tihs, i believe we should do that same. (xlc has nostrict_induction to turn this off, for example, and issues one warning per compilation if it discovers a loop where it could matter. We could simply do the same.)

Follow-Ups:
- Re: -funsafe-loop-optimizations
  - From: Richard Henderson

References:
- -funsafe-loop-optimizations
  - From: Zdenek Dvorak

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