Fix an iterator invalidation bug.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130166 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 1810ded..3f69ce8 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -3788,19 +3788,20 @@
if (!Pair.second)
return Pair.first->second;
- BackedgeTakenInfo BECount = ComputeBackedgeTakenCount(L);
- if (BECount.Exact != getCouldNotCompute()) {
- assert(isLoopInvariant(BECount.Exact, L) &&
- isLoopInvariant(BECount.Max, L) &&
+ BackedgeTakenInfo Result = getCouldNotCompute();
+ BackedgeTakenInfo Computed = ComputeBackedgeTakenCount(L);
+ if (Computed.Exact != getCouldNotCompute()) {
+ assert(isLoopInvariant(Computed.Exact, L) &&
+ isLoopInvariant(Computed.Max, L) &&
"Computed backedge-taken count isn't loop invariant for loop!");
++NumTripCountsComputed;
// Update the value in the map.
- Pair.first->second = BECount;
+ Result = Computed;
} else {
- if (BECount.Max != getCouldNotCompute())
+ if (Computed.Max != getCouldNotCompute())
// Update the value in the map.
- Pair.first->second = BECount;
+ Result = Computed;
if (isa<PHINode>(L->getHeader()->begin()))
// Only count loops that have phi nodes as not being computable.
++NumTripCountsNotComputed;
@@ -3811,7 +3812,7 @@
// conservative estimates made without the benefit of trip count
// information. This is similar to the code in forgetLoop, except that
// it handles SCEVUnknown PHI nodes specially.
- if (BECount.hasAnyInfo()) {
+ if (Computed.hasAnyInfo()) {
SmallVector<Instruction *, 16> Worklist;
PushLoopPHIs(L, Worklist);
@@ -3842,7 +3843,13 @@
PushDefUseChildren(I, Worklist);
}
}
- return Pair.first->second;
+
+ // Re-lookup the insert position, since the call to
+ // ComputeBackedgeTakenCount above could result in a
+ // recusive call to getBackedgeTakenInfo (on a different
+ // loop), which would invalidate the iterator computed
+ // earlier.
+ return BackedgeTakenCounts.find(L)->second = Result;
}
/// forgetLoop - This method should be called by the client when it has