[PATCH] D124807: [clang][dataflow] Avoid assert for invalid cast to BoolValue

[Eric Li via Phabricator via cfe-commits]

li.zhe.hua updated this revision to Diff 426711.
li.zhe.hua added a comment.

Update test to treat the PointerToBool conversion as an opaque boolean 
expression, and test it as such.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D124807/new/

https://reviews.llvm.org/D124807

Files:
  clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
  clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp


Index: clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
===================================================================
--- clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
+++ clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp
@@ -1152,4 +1152,39 @@
       });
 }
 
+// FIXME: Remove this test once it provides no additional test coverage.
+TEST_F(FlowConditionTest, DoesNotAssertForImplicitCastToBool) {
+  std::string Code = R"(
+    void target(int *Ptr) {
+      bool Foo = false;
+      if (Ptr) {
+        Foo = true;
+        /*[[p1]]*/
+      }
+
+      (void)0;
+      /*[[p2]]*/
+    }
+  )";
+  runDataflow(
+      Code, [](llvm::ArrayRef<
+                   std::pair<std::string, DataflowAnalysisState<NoopLattice>>>
+                   Results,
+               ASTContext &ASTCtx) {
+        ASSERT_THAT(Results, ElementsAre(Pair("p2", _), Pair("p1", _)));
+        const ValueDecl *FooDecl = findValueDecl(ASTCtx, "Foo");
+        ASSERT_THAT(FooDecl, NotNull());
+
+        const Environment &Env1 = Results[1].second.Env;
+        auto &FooVal1 =
+            *cast<BoolValue>(Env1.getValue(*FooDecl, SkipPast::Reference));
+        EXPECT_TRUE(Env1.flowConditionImplies(FooVal1));
+
+        const Environment &Env2 = Results[0].second.Env;
+        auto &FooVal2 =
+            *cast<BoolValue>(Env2.getValue(*FooDecl, SkipPast::Reference));
+        EXPECT_FALSE(Env2.flowConditionImplies(FooVal2));
+      });
+}
+
 } // namespace
Index: clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
===================================================================
--- clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
+++ clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
@@ -17,6 +17,7 @@
 #include <vector>
 
 #include "clang/AST/DeclCXX.h"
+#include "clang/AST/IgnoreExpr.h"
 #include "clang/AST/OperationKinds.h"
 #include "clang/AST/StmtVisitor.h"
 #include "clang/Analysis/Analyses/PostOrderCFGView.h"
@@ -68,6 +69,28 @@
   return BlockPos - Pred.succ_begin();
 }
 
+/// Skips past any parentheses and implicit casts for `E`, except if they would
+/// perform a type conversion to bool.
+///
+/// FIXME: Its hard to tell if this is a principled solution or workaround to an
+/// issue. Re-evaluate the necessity for this function after we model pointers
+/// and integers in the framework.
+static const Expr *ignoreParenImpCastsExceptToBool(const Expr *E) {
+  const Expr *LastE = nullptr;
+  while (E != LastE) {
+    LastE = E;
+    E = IgnoreParensSingleStep(const_cast<Expr *>(E));
+
+    bool WasBool = E->getType()->isBooleanType();
+    auto *Unwrapped = IgnoreImplicitCastsExtraSingleStep(const_cast<Expr *>(E));
+    if (WasBool && !Unwrapped->getType()->isBooleanType())
+      return E;
+
+    E = Unwrapped;
+  }
+  return E;
+}
+
 /// Extends the flow condition of an environment based on a terminator
 /// statement.
 class TerminatorVisitor : public ConstStmtVisitor<TerminatorVisitor> {
@@ -77,26 +100,26 @@
       : StmtToEnv(StmtToEnv), Env(Env), BlockSuccIdx(BlockSuccIdx) {}
 
   void VisitIfStmt(const IfStmt *S) {
-    auto *Cond = S->getCond()->IgnoreParenImpCasts();
+    auto *Cond = ignoreParenImpCastsExceptToBool(S->getCond());
     assert(Cond != nullptr);
     extendFlowCondition(*Cond);
   }
 
   void VisitWhileStmt(const WhileStmt *S) {
-    auto *Cond = S->getCond()->IgnoreParenImpCasts();
+    auto *Cond = ignoreParenImpCastsExceptToBool(S->getCond());
     assert(Cond != nullptr);
     extendFlowCondition(*Cond);
   }
 
   void VisitBinaryOperator(const BinaryOperator *S) {
     assert(S->getOpcode() == BO_LAnd || S->getOpcode() == BO_LOr);
-    auto *LHS = S->getLHS()->IgnoreParenImpCasts();
+    auto *LHS = ignoreParenImpCastsExceptToBool(S->getLHS());
     assert(LHS != nullptr);
     extendFlowCondition(*LHS);
   }
 
   void VisitConditionalOperator(const ConditionalOperator *S) {
-    auto *Cond = S->getCond()->IgnoreParenImpCasts();
+    auto *Cond = ignoreParenImpCastsExceptToBool(S->getCond());
     assert(Cond != nullptr);
     extendFlowCondition(*Cond);
   }

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