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BBVectorize: Fix an invalid reference bug

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This fixes PR15289. This bug was introduced (recently) in r175215; collecting
all std::vector references for candidate pairs to delete at once is invalid
because subsequent lookups in the owning DenseMap could invalidate the
references.

bugpoint was able to reduce a useful test case. Unfortunately, because whether
or not this asserts depends on memory layout, this test case will sometimes
appear to produce valid output. Nevertheless, running under valgrind will
reveal the error.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175397 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel
2013-02-17 15:59:26 +00:00
parent a79cbb1232
commit f79f136cc6
2 changed files with 105 additions and 4 deletions
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11
lib/Transforms/Vectorize/BBVectorize.cpp
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@@ -2164,10 +2164,7 @@ namespace {
*S->second << "\n");
// Remove all candidate pairs that have values in the chosen dag.
std::vector<Value *> &KK = CandidatePairs[S->first],
&LL = CandidatePairs2[S->second],
&MM = CandidatePairs[S->second],
&NN = CandidatePairs2[S->first];
std::vector<Value *> &KK = CandidatePairs[S->first];
for (std::vector<Value *>::iterator K = KK.begin(), KE = KK.end();
K != KE; ++K) {
if (*K == S->second)
@@ -2175,6 +2172,8 @@ namespace {
CandidatePairsSet.erase(ValuePair(S->first, *K));
}
std::vector<Value *> &LL = CandidatePairs2[S->second];
for (std::vector<Value *>::iterator L = LL.begin(), LE = LL.end();
L != LE; ++L) {
if (*L == S->first)
@@ -2182,11 +2181,15 @@ namespace {
CandidatePairsSet.erase(ValuePair(*L, S->second));
}
std::vector<Value *> &MM = CandidatePairs[S->second];
for (std::vector<Value *>::iterator M = MM.begin(), ME = MM.end();
M != ME; ++M) {
assert(*M != S->first && "Flipped pair in candidate list?");
CandidatePairsSet.erase(ValuePair(S->second, *M));
}
std::vector<Value *> &NN = CandidatePairs2[S->first];
for (std::vector<Value *>::iterator N = NN.begin(), NE = NN.end();
N != NE; ++N) {
assert(*N != S->second && "Flipped pair in candidate list?");