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[Bug tree-optimization/69297] [6 Regression] Performance regression after r230020
- From: "ysrumyan at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 18 Jan 2016 10:48:56 +0000
- Subject: [Bug tree-optimization/69297] [6 Regression] Performance regression after r230020
- Auto-submitted: auto-generated
- References: <bug-69297-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69297
--- Comment #4 from Yuri Rumyantsev <ysrumyan at gmail dot com> ---
Yes, this loop was added for avoiding dce phase.
Thanks.
Yuri.
2016-01-18 13:33 GMT+03:00 rguenth at gcc dot gnu.org
<gcc-bugzilla@gcc.gnu.org>:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69297
>
> --- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
> With a fix:
>
> t.c:76:10: note: Cost model analysis:
> Vector inside of basic block cost: 376
> Vector prologue cost: 0
> Vector epilogue cost: 0
> Scalar cost of basic block: 96
> t.c:76:10: note: not vectorized: vectorization is not profitable.
>
> Note the reduction loop is still vectorized:
>
> t.c:74:5: note: Cost model analysis:
> Vector inside of loop cost: 3
> Vector prologue cost: 1
> Vector epilogue cost: 7
> Scalar iteration cost: 3
> Scalar outside cost: 0
> Vector outside cost: 8
> prologue iterations: 0
> epilogue iterations: 0
> Calculated minimum iters for profitability: 4
>
> but likely this isn't profitable either?
>
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