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[RewriteStatepointsForGC] Fix iterator invalidation bug

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Inserting into a DenseMap you're iterating over is not well defined.  This is unfortunate since this is well defined on a std::map.

"cleanup per llvm code style standards" bug #2





git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230827 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Philip Reames 2015-02-28 00:47:50 +00:00
parent 63ac784d31
commit dfa22d308f
1 changed files with 11 additions and 2 deletions
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13
lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
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@ -684,12 +684,19 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &cache,
states[def] = PhiState();
// Recursively fill in all phis & selects reachable from the initial one
// for which we don't already know a definite base value for
// PERF: Yes, this is as horribly inefficient as it looks.
// TODO: This should be rewritten with a worklist
bool done = false;
while (!done) {
done = true;
// Since we're adding elements to 'states' as we run, we can't keep
// iterators into the set.
SmallVector<Value*, 16> Keys;
Keys.reserve(states.size());
for (auto Pair : states) {
Value *v = Pair.first;
Value *V = Pair.first;
Keys.push_back(V);
}
for (Value *v : Keys) {
assert(!isKnownBaseResult(v) && "why did it get added?");
if (PHINode *phi = dyn_cast<PHINode>(v)) {
assert(phi->getNumIncomingValues() > 0 &&
@ -734,6 +741,7 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &cache,
while (progress) {
oldSize = states.size();
progress = false;
// We're only changing keys in this loop, thus safe to keep iterators
for (auto Pair : states) {
MeetPhiStates calculateMeet(states);
Value *v = Pair.first;
@ -768,6 +776,7 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &cache,
}
// Insert Phis for all conflicts
// Only changing keys in 'states', thus safe to keep iterators
for (auto Pair : states) {
Instruction *v = cast<Instruction>(Pair.first);
PhiState state = Pair.second;