objc-gc: Fix a corner case where clang fails to generate GC

write barrier with captured pointer to object. // rdar://10150823

llvm-svn: 140399

clang/lib/AST/Expr.cpp

@@ -1728,8 +1728,15 @@ bool Expr::isOBJCGCCandidate(ASTContext &Ctx) const {
                                                       ->isOBJCGCCandidate(Ctx);
   case CStyleCastExprClass:
     return cast<CStyleCastExpr>(E)->getSubExpr()->isOBJCGCCandidate(Ctx);
+  case BlockDeclRefExprClass:
   case DeclRefExprClass: {
-    const Decl *D = cast<DeclRefExpr>(E)->getDecl();
+    
+    const Decl *D;
+    if (const BlockDeclRefExpr *BDRE = dyn_cast<BlockDeclRefExpr>(E))
+        D = BDRE->getDecl();
+    else 
+        D = cast<DeclRefExpr>(E)->getDecl();
+        
     if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
       if (VD->hasGlobalStorage())
         return true;

clang/test/CodeGenObjC/objc2-strong-cast-block-import.m

@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fobjc-gc-only -fblocks  -fobjc-nonfragile-abi -emit-llvm -o - %s | FileCheck %s
+// rdar://10150823
+
+@interface Test {
+@package
+    Test ** __strong objects;
+}
+@end
+
+id newObject();
+void runWithBlock(void(^)(int i));
+
+@implementation Test
+
+- (void)testWithObjectInBlock {
+    Test **children = objects;
+    runWithBlock(^(int i){
+        children[i] = newObject();
+    });
+}
+
+@end
+// CHECK: call i8* @objc_assign_strongCast
+// CHECK: call i8* @objc_assign_strongCast
+