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Re: [PATCH] Fix optimization regression in constant folder
- From: Ian Lance Taylor <iant at google dot com>
- To: Eric Botcazou <ebotcazou at adacore dot com>
- Cc: "Richard Guenther" <richard dot guenther at gmail dot com>, gcc-patches at gcc dot gnu dot org
- Date: 30 Sep 2007 17:09:46 -0700
- Subject: Re: [PATCH] Fix optimization regression in constant folder
- References: <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com>
Eric Botcazou <firstname.lastname@example.org> writes:
> > That doesn't make sense: a type either wraps on overflow or is
> > undefined on overflow.
> Well, I've given the rationale and I stand by it. We already have the
> property that, if flag_strict_overflow is not set, signed types are neither
> TYPE_OVERFLOW_WRAPS nor TYPE_OVERFLOW_UNDEFINED.
Right. A type can be neither. But you were asking for sizetypes to
be both, and that does not make sense.
> > Richard's patch for PR 30364 should test TYPE_OVERFLOW_UNDEFINED, not
> > TYPE_OVERFLOW_WRAPS.
> Makes sense, but that won't change anything as far as Ada is concerned.
Then I don't understand what change you want to make.
I want to move toward eliminating TYPE_IS_SIZETYPE checks from the
middle-end, and capture them entirely in TYPE_OVERFLOW_UNDEFINED: a
sizetype is an unsigned type with undefined overflow.
What prevents us from doing that?