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author | Arnold Schwaighofer <aschwaighofer@apple.com> | 2014-01-19 03:18:31 +0000 |
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committer | Arnold Schwaighofer <aschwaighofer@apple.com> | 2014-01-19 03:18:31 +0000 |
commit | 2becaaf3a15a8815f93e65f768038427051ee004 (patch) | |
tree | 41045d50bc61e13cc302f4647f9bf6604c236f23 /lib/Transforms/Vectorize | |
parent | e608d695de5c8b8de80041d9b654f42b1d7fb893 (diff) | |
download | llvm-2becaaf3a15a8815f93e65f768038427051ee004.tar.gz llvm-2becaaf3a15a8815f93e65f768038427051ee004.tar.bz2 llvm-2becaaf3a15a8815f93e65f768038427051ee004.tar.xz |
LoopVectorizer: A reduction that has multiple uses of the reduction value is not
a reduction.
Really. Under certain circumstances (the use list of an instruction has to be
set up right - hence the extra pass in the test case) we would not recognize
when a value in a potential reduction cycle was used multiple times by the
reduction cycle.
Fixes PR18526.
radar://15851149
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199570 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/Vectorize')
-rw-r--r-- | lib/Transforms/Vectorize/LoopVectorize.cpp | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp index c05288bd07..695ee03ea7 100644 --- a/lib/Transforms/Vectorize/LoopVectorize.cpp +++ b/lib/Transforms/Vectorize/LoopVectorize.cpp @@ -4535,13 +4535,22 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi, continue; } - // Process instructions only once (termination). + // Process instructions only once (termination). Each reduction cycle + // value must only be used once, except by phi nodes and min/max + // reductions which are represented as a cmp followed by a select. + ReductionInstDesc IgnoredVal(false, 0); if (VisitedInsts.insert(Usr)) { if (isa<PHINode>(Usr)) PHIs.push_back(Usr); else NonPHIs.push_back(Usr); - } + } else if (!isa<PHINode>(Usr) && + ((!isa<FCmpInst>(Usr) && + !isa<ICmpInst>(Usr) && + !isa<SelectInst>(Usr)) || + !isMinMaxSelectCmpPattern(Usr, IgnoredVal).IsReduction)) + return false; + // Remember that we completed the cycle. if (Usr == Phi) FoundStartPHI = true; |