[PATCH] D128848: Fix assertion when analyzing a for-loop with no condition expression

[Eric Li via Phabricator via cfe-commits]

li.zhe.hua created this revision.
li.zhe.hua added a reviewer: ymandel.
Herald added a project: All.
li.zhe.hua requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

For loops are allowed to have an empty conditional expression; we
should not assert that it must have one.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D128848

Files:
  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
@@ -10,7 +10,6 @@
 #include "TestingSupport.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Decl.h"
-#include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Analysis/FlowSensitive/DataflowEnvironment.h"
 #include "clang/Analysis/FlowSensitive/StorageLocation.h"
@@ -3827,4 +3826,42 @@
       });
 }
 
+TEST_F(TransferTest, ForStmtEmptyBranchExtendsFlowCondition) {
+  std::string Code = R"cc(
+    void target(bool Foo) {
+      for (;;) {
+        if (!Foo) {
+          break;
+        }
+        (void)0;
+        // [[loop_body]]
+      }
+      (void)0;
+      // [[after_loop]]
+    }
+  )cc";
+  runDataflow(
+      Code, [](llvm::ArrayRef<
+                   std::pair<std::string, DataflowAnalysisState<NoopLattice>>>
+                   Results,
+               ASTContext &ASTCtx) {
+        ASSERT_THAT(Results,
+                    ElementsAre(Pair("after_loop", _), Pair("loop_body", _)));
+        const Environment &LoopBodyEnv = Results[1].second.Env;
+        const Environment &AfterLoopEnv = Results[0].second.Env;
+
+        const ValueDecl *FooDecl = findValueDecl(ASTCtx, "Foo");
+        ASSERT_THAT(FooDecl, NotNull());
+
+        BoolValue &LoopBodyFooVal =
+            *cast<BoolValue>(LoopBodyEnv.getValue(*FooDecl, SkipPast::None));
+        EXPECT_TRUE(LoopBodyEnv.flowConditionImplies(LoopBodyFooVal));
+
+        BoolValue &AfterLoopFooVal =
+            *cast<BoolValue>(AfterLoopEnv.getValue(*FooDecl, SkipPast::None));
+        EXPECT_TRUE(AfterLoopEnv.flowConditionImplies(
+            AfterLoopEnv.makeNot(AfterLoopFooVal)));
+      });
+}
+
 } // namespace
Index: clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
===================================================================
--- clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
+++ clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
@@ -97,7 +97,8 @@
 
   void VisitForStmt(const ForStmt *S) {
     auto *Cond = S->getCond();
-    assert(Cond != nullptr);
+    if (Cond == nullptr)
+      return;
     extendFlowCondition(*Cond);
   }
 



Index: clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
===================================================================
--- clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
+++ clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
@@ -10,7 +10,6 @@
 #include "TestingSupport.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Decl.h"
-#include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Analysis/FlowSensitive/DataflowEnvironment.h"
 #include "clang/Analysis/FlowSensitive/StorageLocation.h"
@@ -3827,4 +3826,42 @@
       });
 }
 
+TEST_F(TransferTest, ForStmtEmptyBranchExtendsFlowCondition) {
+  std::string Code = R"cc(
+    void target(bool Foo) {
+      for (;;) {
+        if (!Foo) {
+          break;
+        }
+        (void)0;
+        // [[loop_body]]
+      }
+      (void)0;
+      // [[after_loop]]
+    }
+  )cc";
+  runDataflow(
+      Code, [](llvm::ArrayRef<
+                   std::pair<std::string, DataflowAnalysisState<NoopLattice>>>
+                   Results,
+               ASTContext &ASTCtx) {
+        ASSERT_THAT(Results,
+                    ElementsAre(Pair("after_loop", _), Pair("loop_body", _)));
+        const Environment &LoopBodyEnv = Results[1].second.Env;
+        const Environment &AfterLoopEnv = Results[0].second.Env;
+
+        const ValueDecl *FooDecl = findValueDecl(ASTCtx, "Foo");
+        ASSERT_THAT(FooDecl, NotNull());
+
+        BoolValue &LoopBodyFooVal =
+            *cast<BoolValue>(LoopBodyEnv.getValue(*FooDecl, SkipPast::None));
+        EXPECT_TRUE(LoopBodyEnv.flowConditionImplies(LoopBodyFooVal));
+
+        BoolValue &AfterLoopFooVal =
+            *cast<BoolValue>(AfterLoopEnv.getValue(*FooDecl, SkipPast::None));
+        EXPECT_TRUE(AfterLoopEnv.flowConditionImplies(
+            AfterLoopEnv.makeNot(AfterLoopFooVal)));
+      });
+}
+
 } // namespace
Index: clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
===================================================================
--- clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
+++ clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
@@ -97,7 +97,8 @@
 
   void VisitForStmt(const ForStmt *S) {
     auto *Cond = S->getCond();
-    assert(Cond != nullptr);
+    if (Cond == nullptr)
+      return;
     extendFlowCondition(*Cond);
   }
 

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