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[Bug tree-optimization/33711] Missed optimization: reduction by subtraction (vectorizer)
- From: "eres at il dot ibm dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 9 Oct 2007 13:49:59 -0000
- Subject: [Bug tree-optimization/33711] Missed optimization: reduction by subtraction (vectorizer)
- References: <bug-33711-13229@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #1 from eres at il dot ibm dot com 2007-10-09 13:49 -------
The loop in the above example does not get vectorized because of the
subtraction in reduction; which is currently not supported.
Taken from the vectorizer dump:
test.c:19: note: worklist: examine stmt: udiff_7 = udiff_20 - D.2210_6
test.c:19: note: vect_is_simple_use: operand udiff_20
test.c:19: note: def_stmt: udiff_20 = PHI <udiff_7(4), 1.5e+3(2)>
test.c:19: note: Unsupported pattern.
test.c:19: note: not vectorized: unsupported use in stmt.
test.c:19: note: unexpected pattern.
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33711