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[Bug c/56083] Vectorizer uses xor/movlps/movhps rather than movups
- From: "glisse at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 23 Jan 2013 16:17:02 +0000
- Subject: [Bug c/56083] Vectorizer uses xor/movlps/movhps rather than movups
- Auto-submitted: auto-generated
- References: <bug-56083-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56083
Marc Glisse <glisse at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |glisse at gcc dot gnu.org
--- Comment #2 from Marc Glisse <glisse at gcc dot gnu.org> 2013-01-23 16:17:02 UTC ---
(In reply to comment #1)
> This is tuning decision,
Uros, I completely agree, but note that the PR also mentions this line:
xorps %xmm0, %xmm0
which appears rather useless since the low and high parts are overwritten on
the next 2 lines. Is this done on purpose to kill dependencies or something? Or
is it a missed optimization? (simplify-rtx (or another place) is indeed missing
a few things in that area)