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[Bug tree-optimization/79934] Vectorization of descending-index loops can produce unnecessary permutes
- 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: Tue, 07 Mar 2017 08:23:36 +0000
- Subject: [Bug tree-optimization/79934] Vectorization of descending-index loops can produce unnecessary permutes
- Auto-submitted: auto-generated
- References: <bug-79934-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79934
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2017-03-07
Blocks| |53947
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Generally a known weakness of the vectorizer and difficult to fix inside it.
Still a fix in the vectorizer itself is wanted as cost modeling should better
know about such optimization opportunities.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations