[clang] 8e1d2f2 - [clang][dataflow] Don't crash when BlockToState is called from unreachable path (#65732)
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Fri Sep 8 07:24:11 PDT 2023
Author: Kinuko Yasuda
Date: 2023-09-08T10:24:08-04:00
New Revision: 8e1d2f2f12243d284b729174fc0720052ea5518c
URL: https://github.com/llvm/llvm-project/commit/8e1d2f2f12243d284b729174fc0720052ea5518c
DIFF: https://github.com/llvm/llvm-project/commit/8e1d2f2f12243d284b729174fc0720052ea5518c.diff
LOG: [clang][dataflow] Don't crash when BlockToState is called from unreachable path (#65732)
When we call `getEnvironment`, `BlockToState[BlockId]` for the block can
return null even if CFCtx.isBlockReachable(B) returns true if it is
called from a particular block that is marked unreachable to the block.
Added:
Modified:
clang/lib/Analysis/FlowSensitive/Transfer.cpp
clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
Removed:
################################################################################
diff --git a/clang/lib/Analysis/FlowSensitive/Transfer.cpp b/clang/lib/Analysis/FlowSensitive/Transfer.cpp
index 67d8be392ae6053..b46c947c691b9b9 100644
--- a/clang/lib/Analysis/FlowSensitive/Transfer.cpp
+++ b/clang/lib/Analysis/FlowSensitive/Transfer.cpp
@@ -43,7 +43,20 @@ const Environment *StmtToEnvMap::getEnvironment(const Stmt &S) const {
if (!CFCtx.isBlockReachable(*BlockIt->getSecond()))
return nullptr;
const auto &State = BlockToState[BlockIt->getSecond()->getBlockID()];
- assert(State);
+ if (!(State)) {
+ LLVM_DEBUG({
+ // State can be null when this block is unreachable from the block that
+ // called this method.
+ bool hasUnreachableEdgeFromPred = false;
+ for (auto B : BlockIt->getSecond()->preds())
+ if (!B) {
+ hasUnreachableEdgeFromPred = true;
+ break;
+ }
+ assert(hasUnreachableEdgeFromPred);
+ });
+ return nullptr;
+ }
return &State->Env;
}
diff --git a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
index 177970ac52a67eb..ec07555d7f33b3b 100644
--- a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
@@ -5853,4 +5853,24 @@ TEST(TransferTest, AnonymousStructWithReferenceField) {
});
}
+TEST(TransferTest, EvaluateBlockWithUnreachablePreds) {
+ // This is a crash repro.
+ // `false` block may not have been processed when we try to evalute the `||`
+ // after visiting `true`, because it is not necessary (and therefore the edge
+ // is marked unreachable). Trying to get the analysis state via
+ // `getEnvironment` for the subexpression still should not crash.
+ std::string Code = R"(
+ int cast(int i) {
+ if ((i < 0 && true) || false) {
+ return 0;
+ }
+ return 0;
+ }
+ )";
+ runDataflow(
+ Code,
+ [](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
+ ASTContext &ASTCtx) {});
+}
+
} // namespace
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