summaryrefslogtreecommitdiff
path: root/lib
diff options
context:
space:
mode:
authorBenjamin Kramer <benny.kra@googlemail.com>2013-04-18 14:29:13 +0000
committerBenjamin Kramer <benny.kra@googlemail.com>2013-04-18 14:29:13 +0000
commit403fc143709bfe5cf014929d633c0b1c28f6e0c9 (patch)
tree8fa9d264a4d1c4486de6f69c6203ffea870b4e04 /lib
parentd050e96133fac8565e3bb1eabe9a587dd5a6ac4d (diff)
LoopVectorize: Use a set to avoid longer cycles in the reduction chain too.
Fixes PR15748. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179757 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r--lib/Transforms/Vectorize/LoopVectorize.cpp14
1 files changed, 6 insertions, 8 deletions
diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index 238fc8bfb70..f40964f813d 100644
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -2733,7 +2733,10 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
// used as reduction variables (such as ADD). We may have a single
// out-of-block user. The cycle must end with the original PHI.
Instruction *Iter = Phi;
- while (true) {
+
+ // Avoid cycles in the chain.
+ SmallPtrSet<Instruction *, 8> VisitedInsts;
+ while (VisitedInsts.insert(Iter)) {
// If the instruction has no users then this is a broken
// chain and can't be a reduction variable.
if (Iter->use_empty())
@@ -2747,9 +2750,6 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
// Is this a bin op ?
FoundBinOp |= !isa<PHINode>(Iter);
- // Remember the current instruction.
- Instruction *OldIter = Iter;
-
// For each of the *users* of iter.
for (Value::use_iterator it = Iter->use_begin(), e = Iter->use_end();
it != e; ++it) {
@@ -2795,10 +2795,6 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
Iter = U;
}
- // If all uses were skipped this can't be a reduction variable.
- if (Iter == OldIter)
- return false;
-
// We found a reduction var if we have reached the original
// phi node and we only have a single instruction with out-of-loop
// users.
@@ -2814,6 +2810,8 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
return FoundBinOp && ExitInstruction;
}
}
+
+ return false;
}
bool