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-rw-r--r--lib/Transforms/Vectorize/LoopVectorize.cpp13
1 files changed, 11 insertions, 2 deletions
diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index 5e758713ed..f9f6b18940 100644
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4191,13 +4191,22 @@ 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;