1 files changed, 31 insertions, 3 deletions
diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index ba5eceda24b5..87c2f6f9f08f 100644
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -542,6 +542,7 @@ private:
   // Visitors to walk an AST and construct the CFG.
   CFGBlock *VisitInitListExpr(InitListExpr *ILE, AddStmtChoice asc);
   CFGBlock *VisitAddrLabelExpr(AddrLabelExpr *A, AddStmtChoice asc);
+  CFGBlock *VisitAttributedStmt(AttributedStmt *A, AddStmtChoice asc);
   CFGBlock *VisitBinaryOperator(BinaryOperator *B, AddStmtChoice asc);
   CFGBlock *VisitBreakStmt(BreakStmt *B);
   CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc);
@@ -2149,6 +2150,9 @@ CFGBlock *CFGBuilder::Visit(Stmt * S, AddStmtChoice asc,
     case Stmt::InitListExprClass:
       return VisitInitListExpr(cast<InitListExpr>(S), asc);
 
+    case Stmt::AttributedStmtClass:
+      return VisitAttributedStmt(cast<AttributedStmt>(S), asc);
+
     case Stmt::AddrLabelExprClass:
       return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc);
 
@@ -2398,8 +2402,32 @@ CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A,
   return Block;
 }
 
-CFGBlock *CFGBuilder::VisitUnaryOperator(UnaryOperator *U,
-           AddStmtChoice asc) {
+static bool isFallthroughStatement(const AttributedStmt *A) {
+  bool isFallthrough = hasSpecificAttr<FallThroughAttr>(A->getAttrs());
+  assert((!isFallthrough || isa<NullStmt>(A->getSubStmt())) &&
+         "expected fallthrough not to have children");
+  return isFallthrough;
+}
+
+CFGBlock *CFGBuilder::VisitAttributedStmt(AttributedStmt *A,
+                                          AddStmtChoice asc) {
+  // AttributedStmts for [[likely]] can have arbitrary statements as children,
+  // and the current visitation order here would add the AttributedStmts
+  // for [[likely]] after the child nodes, which is undesirable: For example,
+  // if the child contains an unconditional return, the [[likely]] would be
+  // considered unreachable.
+  // So only add the AttributedStmt for FallThrough, which has CFG effects and
+  // also no children, and omit the others. None of the other current StmtAttrs
+  // have semantic meaning for the CFG.
+  if (isFallthroughStatement(A) && asc.alwaysAdd(*this, A)) {
+    autoCreateBlock();
+    appendStmt(Block, A);
+  }
+
+  return VisitChildren(A);
+}
+
+CFGBlock *CFGBuilder::VisitUnaryOperator(UnaryOperator *U, AddStmtChoice asc) {
   if (asc.alwaysAdd(*this, U)) {
     autoCreateBlock();
     appendStmt(Block, U);
@@ -3333,7 +3361,7 @@ CFGBlock *CFGBuilder::VisitGCCAsmStmt(GCCAsmStmt *G, AddStmtChoice asc) {
   // Save "Succ" in BackpatchBlocks. In the backpatch processing, "Succ" is
   // used to avoid adding "Succ" again.
   BackpatchBlocks.push_back(JumpSource(Succ, ScopePos));
-  return Block;
+  return VisitChildren(G);
 }
 
 CFGBlock *CFGBuilder::VisitForStmt(ForStmt *F) {