Implement an indirect-goto optimization for goto *&&lbl and respect this

in the scope checker.  With that done, turn an indirect goto into a
protected scope into a hard error;  otherwise IR generation has to start
worrying about declarations not dominating their scopes, as exemplified
in PR8473.

If this really affects anyone, I can probably adjust this to only hard-error
on possible indirect gotos into VLA scopes rather than arbitrary scopes.
But we'll see how people cope with the aggressive change on the marginal
feature.

llvm-svn: 117539

1 files changed, 6 insertions, 2 deletions

diff --git a/clang/lib/AST/Stmt.cpp b/clang/lib/AST/Stmt.cpp
index 4f46b350408..09d889e9234 100644
--- a/clang/lib/AST/Stmt.cpp
+++ b/clang/lib/AST/Stmt.cpp
@@ -669,8 +669,12 @@ Stmt::child_iterator GotoStmt::child_begin() { return child_iterator(); }
 Stmt::child_iterator GotoStmt::child_end() { return child_iterator(); }
 
 // IndirectGotoStmt
-Expr* IndirectGotoStmt::getTarget() { return cast<Expr>(Target); }
-const Expr* IndirectGotoStmt::getTarget() const { return cast<Expr>(Target); }
+LabelStmt *IndirectGotoStmt::getConstantTarget() {
+  if (AddrLabelExpr *E =
+        dyn_cast<AddrLabelExpr>(getTarget()->IgnoreParenImpCasts()))
+    return E->getLabel();
+  return 0;
+}
 
 Stmt::child_iterator IndirectGotoStmt::child_begin() { return &Target; }
 Stmt::child_iterator IndirectGotoStmt::child_end() { return &Target+1; }