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Re: [patch] for PRs 27639 and 26719
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- Cc: Richard Guenther <rguenther at suse dot de>, gcc-patches at gcc dot gnu dot org, sebastian dot pop at cri dot ensmp dot fr
- Date: Thu, 6 Jul 2006 16:43:31 +0200
- Subject: Re: [patch] for PRs 27639 and 26719
- References: <20060520192624.GA28713@atrey.karlin.mff.cuni.cz> <200607061602.42940.ebotcazou@adacore.com> <20060706141920.GA1710@atrey.karlin.mff.cuni.cz>
> You cannot handle the types differently in scev_probably_wraps_p and in
> convert_affine_scev.
Could you elaborate? Why is it not OK to be more conservative in both
functions for subtypes? In particular, I don't understand why returning true
from scev_probably_wraps_p more often would be problematic.
/* Return false only when the induction variable BASE + STEP * I is
known to not overflow: i.e. when the number of iterations is small
enough with respect to the step and initial condition in order to
keep the evolution confined in TYPEs bounds. Return true when the
iv is known to overflow or when the property is not computable.
--
Eric Botcazou