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[Bug middle-end/63311] [4.9/5 Regression] -O1 optimization introduces valgrind warning
- From: "Joost.VandeVondele at mat dot ethz.ch" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 24 Nov 2014 13:54:43 +0000
- Subject: [Bug middle-end/63311] [4.9/5 Regression] -O1 optimization introduces valgrind warning
- Auto-submitted: auto-generated
- References: <bug-63311-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63311
--- Comment #8 from Joost VandeVondele <Joost.VandeVondele at mat dot ethz.ch> ---
(In reply to Richard Biener from comment #7)
> Confirmed that it is ifcombine. Not sure if I'd call it wrong-code though.
>
> Note that there are no default-defs involved thus ifcombine doesn't see
> must-uninits and disabling its transform when maybe-uninits are seen
> is IMHO bogus.
>
> Not sure what to do about this one. There is no way to preserve evaluation
> order (no andif / orif on gimple).
just wondering if the 'target splitting the condition back' means if has a
choice which of the two to evaluate first. Be means of heuristic, if one of the
two conditions contains a 'maybe-uninit' and the other not, it is presumably
best to evaluate the 'maybe-uninit' one at the second stage ?
>From a usability point of view, I had to touch a couple of spots in our code to
make valgrind testing possible again, so while I wouldn't call this wrong-code,
it certainly is some user-visible behavior.