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Require chained analyses in BasicAA and AAResults to be transitive

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This patch fixes a bug that could result in miscompiles (at least
in an OOT target). The problem could be seen by adding checks that
the DominatorTree used in BasicAliasAnalysis and ValueTracking was
valid (e.g. by adding DT->verify() call before every DT dereference
and then running all tests in test/CodeGen).

Problem was that the LegacyPassManager calculated "last user"
incorrectly for passes such as the DominatorTree when not telling
the pass manager that there was a transitive dependency between
the different analyses. And then it could happen that an incorrect
dominator tree was used when doing alias analysis (which was a pretty
serious bug as the alias analysis result could be invalid).

Fixes: https://bugs.llvm.org/show_bug.cgi?id=48709

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D94138
This commit is contained in:
Bjorn Pettersson 2021-01-02 00:05:53 +01:00
parent 8fb012df95
commit 0798093f86
4 changed files with 5 additions and 7 deletions
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4
lib/Analysis/AliasAnalysis.cpp
View File

@ -883,8 +883,8 @@ bool AAResultsWrapperPass::runOnFunction(Function &F) {
void AAResultsWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<BasicAAWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
AU.addRequiredTransitive<BasicAAWrapperPass>();
AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
// We also need to mark all the alias analysis passes we will potentially
// probe in runOnFunction as used here to ensure the legacy pass manager

6
lib/Analysis/BasicAliasAnalysis.cpp
View File

@ -1899,9 +1899,9 @@ bool BasicAAWrapperPass::runOnFunction(Function &F) {
void BasicAAWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<AssumptionCacheTracker>();
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
AU.addRequiredTransitive<AssumptionCacheTracker>();
AU.addRequiredTransitive<DominatorTreeWrapperPass>();
AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
AU.addUsedIfAvailable<PhiValuesWrapperPass>();
}

1
lib/Target/Hexagon/HexagonLoopIdiomRecognition.cpp
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@ -165,7 +165,6 @@ public:
AU.addRequiredID(LoopSimplifyID);
AU.addRequiredID(LCSSAID);
AU.addRequired<AAResultsWrapperPass>();
AU.addPreserved<AAResultsWrapperPass>();
AU.addRequired<ScalarEvolutionWrapperPass>();
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();

1
lib/Transforms/Scalar/GVNHoist.cpp
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@ -547,7 +547,6 @@ public:
AU.addPreserved<DominatorTreeWrapperPass>();
AU.addPreserved<MemorySSAWrapperPass>();
AU.addPreserved<GlobalsAAWrapperPass>();
AU.addPreserved<AAResultsWrapperPass>();
}
};