[PATCH] D149640: [clang][dataflow] Change PruneTriviallyFalseEdges for building CFG

[Kinuko Yasuda via Phabricator via cfe-commits]

kinu updated this revision to Diff 519029.
kinu added a comment.

Updated the stale comment.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D149640/new/

https://reviews.llvm.org/D149640

Files:
  clang/lib/Analysis/FlowSensitive/ControlFlowContext.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
@@ -2643,7 +2643,7 @@
     void target(int *Foo) {
       do {
         int Bar = *Foo;
-      } while (true);
+      } while (false);
       (void)0;
       /*[[p]]*/
     }
@@ -2674,6 +2674,24 @@
       });
 }
 
+TEST(TransferTest, UnreachableAfterWhileTrue) {
+  std::string Code = R"(
+    void target() {
+      while (true) {}
+      (void)0;
+      /*[[p]]*/
+    }
+  )";
+  runDataflow(
+      Code,
+      [](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
+         ASTContext &ASTCtx) {
+        // The node after the while-true is pruned because it is trivially
+        // known to be unreachable.
+        ASSERT_TRUE(Results.empty());
+      });
+}
+
 TEST(TransferTest, AggregateInitialization) {
   std::string BracesCode = R"(
     struct A {
Index: clang/lib/Analysis/FlowSensitive/ControlFlowContext.cpp
===================================================================
--- clang/lib/Analysis/FlowSensitive/ControlFlowContext.cpp
+++ clang/lib/Analysis/FlowSensitive/ControlFlowContext.cpp
@@ -70,7 +70,7 @@
 llvm::Expected<ControlFlowContext>
 ControlFlowContext::build(const Decl *D, Stmt &S, ASTContext &C) {
   CFG::BuildOptions Options;
-  Options.PruneTriviallyFalseEdges = false;
+  Options.PruneTriviallyFalseEdges = true;
   Options.AddImplicitDtors = true;
   Options.AddTemporaryDtors = true;
   Options.AddInitializers = true;


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