[PATCH] D117754: [clang][dataflow] Intersect ExprToLoc when joining environments

[Stanislav Gatev via Phabricator via cfe-commits]

sgatev created this revision.
sgatev added reviewers: ymandel, xazax.hun, gribozavr2.
Herald added subscribers: steakhal, rnkovacs.
sgatev requested review of this revision.
Herald added a project: clang.

This is part of the implementation of the dataflow analysis framework.
See "[RFC] A dataflow analysis framework for Clang AST" on cfe-dev.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D117754

Files:
  clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp
  clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
  clang/unittests/Analysis/FlowSensitive/TransferTest.cpp


Index: clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
===================================================================
--- clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
+++ clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
@@ -1828,4 +1828,41 @@
       });
 }
 
+TEST_F(TransferTest, VarDeclInDoWhile) {
+  std::string Code = R"(
+    void target(int *Foo) {
+      do {
+        int Bar = *Foo;
+      } while (true);
+      (void)0;
+      /*[[p]]*/
+    }
+  )";
+  runDataflow(Code,
+              [](llvm::ArrayRef<
+                     std::pair<std::string, DataflowAnalysisState<NoopLattice>>>
+                     Results,
+                 ASTContext &ASTCtx) {
+                ASSERT_THAT(Results, ElementsAre(Pair("p", _)));
+                const Environment &Env = Results[0].second.Env;
+
+                const ValueDecl *FooDecl = findValueDecl(ASTCtx, "Foo");
+                ASSERT_THAT(FooDecl, NotNull());
+
+                const ValueDecl *BarDecl = findValueDecl(ASTCtx, "Bar");
+                ASSERT_THAT(BarDecl, NotNull());
+
+                const auto *FooVal =
+                    cast<PointerValue>(Env.getValue(*FooDecl, SkipPast::None));
+                const auto *FooPointeeVal =
+                    cast<IntegerValue>(Env.getValue(FooVal->getPointeeLoc()));
+
+                const auto *BarVal = dyn_cast_or_null<IntegerValue>(
+                    Env.getValue(*BarDecl, SkipPast::None));
+                ASSERT_THAT(BarVal, NotNull());
+
+                EXPECT_EQ(BarVal, FooPointeeVal);
+              });
+}
+
 } // namespace
Index: clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
===================================================================
--- clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
+++ clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include <memory>
+#include <set>
 #include <utility>
 #include <vector>
 
@@ -43,7 +44,9 @@
     std::vector<llvm::Optional<TypeErasedDataflowAnalysisState>> &BlockStates,
     const CFGBlock &Block, const Environment &InitEnv,
     TypeErasedDataflowAnalysis &Analysis) {
-  llvm::DenseSet<const CFGBlock *> Preds;
+  // Ensure the order of predecessor blocks is deterministic to avoid flakiness
+  // in tests.
+  std::set<const CFGBlock *> Preds;
   Preds.insert(Block.pred_begin(), Block.pred_end());
   if (Block.getTerminator().isTemporaryDtorsBranch()) {
     // This handles a special case where the code that produced the CFG includes
Index: clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp
===================================================================
--- clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp
+++ clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp
@@ -83,6 +83,11 @@
   if (DeclToLocSizeBefore != DeclToLoc.size())
     Effect = LatticeJoinEffect::Changed;
 
+  const unsigned ExprToLocSizeBefore = ExprToLoc.size();
+  ExprToLoc = intersectDenseMaps(ExprToLoc, Other.ExprToLoc);
+  if (ExprToLocSizeBefore != ExprToLoc.size())
+    Effect = LatticeJoinEffect::Changed;
+
   // FIXME: Add support for joining distinct values that are assigned to the
   // same storage locations in `LocToVal` and `Other.LocToVal`.
   const unsigned LocToValSizeBefore = LocToVal.size();


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