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[Bug tree-optimization/47538] [4.6 Regression] GNU Scientific Library miscompiled by gcc 4.6
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 31 Jan 2011 10:44:42 +0000
- Subject: [Bug tree-optimization/47538] [4.6 Regression] GNU Scientific Library miscompiled by gcc 4.6
- Auto-submitted: auto-generated
- References: <bug-47538-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47538
--- Comment #11 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-31 10:44:08 UTC ---
(In reply to comment #9)
> > Why do we need something so ill-designed as sizetype? Just for Ada?
>
> Yes, they are useful for Ada, but the _original_ design; the POINTER_PLUS_EXPR
> mistake is orthogonal to it and shouldn't be an excuse to eliminate them.
I agree with that POINTER_PLUS_EXPR shouldn't have used sizetype.
But - the problem with sizetype is not that they exist (and have that
special overflow behavior), but - that sizetypes are considered
always sign-extended despite TYPE_UNSIGNED saying "yes!". That's a
very very very bad design mistake. I tried to "fix" that mistake
at least two times IIRC but failed.
At the end -> no-undefined-overflow branch (no more sizetype).