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[Bug middle-end/68542] [6 Regression] 10% 481.wrf performance regression
- 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: Wed, 25 Nov 2015 14:39:00 +0000
- Subject: [Bug middle-end/68542] [6 Regression] 10% 481.wrf performance regression
- Auto-submitted: auto-generated
- References: <bug-68542-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68542
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Ok, so previously we if-converted but with versioning and thus the if-converted
loop was not vectorized and thrown away?
So yes, for such cases we'd ideally have vector control-flow
if (!all-zero)
{
...
}
but best by not if-converting this in the first place. Note that the
above also applies to "regular" vectorization of if-converted code,
not only to 'masks' as with Yuris patch. I wonder if we can extend
that to re-introduce control flow. A vector == 0 check should be
fairly cheap and the transform keyed on how much code we can execute
conditionally.