[CodeGen][ObjC] Do not call objc_storeStrong when initializing a

constexpr variable.

When compiling a constexpr NSString initialized with an objective-c
string literal, CodeGen emits objc_storeStrong on an uninitialized
alloca, which causes a crash.

This patch folds the code in EmitScalarInit into EmitStoreThroughLValue
and fixes the crash by calling objc_retain on the string instead of
using objc_storeStrong.

rdar://problem/28562009

Differential Revision: https://reviews.llvm.org/D25547

llvm-svn: 284516

1 files changed, 18 insertions, 0 deletions

diff --git a/clang/test/CodeGenObjCXX/arc-constexpr.mm b/clang/test/CodeGenObjCXX/arc-constexpr.mm
new file mode 100644
index 00000000000..786e2cb8f2c
--- /dev/null
+++ b/clang/test/CodeGenObjCXX/arc-constexpr.mm
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -fobjc-arc -o - -std=c++11 %s | FileCheck %s
+
+// CHECK: %[[TYPE:[a-z0-9]+]] = type opaque
+// CHECK: @[[CFSTRING:[a-z0-9_]+]] = private global %struct.__NSConstantString_tag
+
+// CHECK: define void @_Z5test1v
+// CHECK:   %[[ALLOCA:[A-Z]+]] = alloca %[[TYPE]]*
+// CHECK:   %[[V0:[0-9]+]] = call i8* @objc_retain(i8* bitcast (%struct.__NSConstantString_tag* @[[CFSTRING]]
+// CHECK:   %[[V1:[0-9]+]] = bitcast i8* %[[V0]] to %[[TYPE]]*
+// CHECK:   store %[[TYPE]]* %[[V1]], %[[TYPE]]** %[[ALLOCA]]
+// CHECK:   %[[V2:[0-9]+]] = bitcast %[[TYPE]]** %[[ALLOCA]]
+// CHECK:   call void @objc_storeStrong(i8** %[[V2]], i8* null)
+
+@class NSString;
+
+void test1() {
+  constexpr NSString *S = @"abc";
+}