CFG: Delay creating Dtors for CompoundStmts which end in ReturnStmt

Summary:
VisitReturnStmt would create a new block with including Dtors, so the Dtors created
in VisitCompoundStmts would be in an unreachable block.

Example:

struct S {
  ~S();
};

void f()
{
  S s;
  return;
}

void g()
{
  S s;
}

Before this patch, f has one additional unreachable block containing just the
destructor of S. With this patch, both f and g have the same blocks.

Reviewers: krememek

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D13973

llvm-svn: 253107

1 files changed, 9 insertions, 1 deletions

diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index 6cb63f2b175..fba9a41f232 100644
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -1942,7 +1942,15 @@ CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C,
 
 
 CFGBlock *CFGBuilder::VisitCompoundStmt(CompoundStmt *C) {
-  addLocalScopeAndDtors(C);
+  LocalScope::const_iterator scopeBeginPos = ScopePos;
+  if (BuildOpts.AddImplicitDtors) {
+    addLocalScopeForStmt(C);
+  }
+  if (!C->body_empty() && !isa<ReturnStmt>(*C->body_rbegin())) {
+    // If the body ends with a ReturnStmt, the dtors will be added in VisitReturnStmt
+    addAutomaticObjDtors(ScopePos, scopeBeginPos, C);
+  }
+
   CFGBlock *LastBlock = Block;
 
   for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend();