From 59a53fa3f8ea73bae52ea36d0038f76e9f10729c Mon Sep 17 00:00:00 2001
From: Fariborz Jahanian <fjahanian@apple.com>
Date: Wed, 16 Sep 2009 18:09:18 +0000
Subject: [PATCH] Do not generate write-barrier in indirect assignment to a
 weak object.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@82061 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/AST/Expr.cpp                     | 6 ++++--
 test/CodeGenObjC/objc2-weak-assign.m | 4 ++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 0ac896c783..4f2d47ec2f 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -1117,8 +1117,10 @@ bool Expr::isOBJCGCCandidate(ASTContext &Ctx) const {
       if (VD->hasGlobalStorage())
         return true;
       QualType T = VD->getType();
-      // dereferencing to a pointer is always a gc'able candidate
-      return T->isPointerType();
+      // dereferencing to a  pointer is always a gc'able candidate,
+      // unless it is __weak.
+      return T->isPointerType() && 
+             (Ctx.getObjCGCAttrKind(T) != QualType::Weak);
     }
     return false;
   }
diff --git a/test/CodeGenObjC/objc2-weak-assign.m b/test/CodeGenObjC/objc2-weak-assign.m
index a3740b207e..635ca38df4 100644
--- a/test/CodeGenObjC/objc2-weak-assign.m
+++ b/test/CodeGenObjC/objc2-weak-assign.m
@@ -9,6 +9,10 @@ __weak id* a1[20];
 id* __weak a2[30];
 id** __weak a3[40];
 
+void foo (__weak id *param) {
+ *param = 0;
+}
+
 int main()
 {
 	*x = 0;
-- 
2.40.0