[ObjC][ARC] Don't enter the cleanup scope if the initializer expression isn't an ExprWithCleanups

[ahatanak]

Summary

This patch fixes a bug where a temporary ObjC pointer is released before the end of the full expression.

This fixes PR50043.

rdar://77030453

[rjmccall]

Okay, LGTM.

clang/lib/CodeGen/CGDecl.cpp

if (!lifetime) {
     return;
   }
 
   if (const CXXDefaultInitExpr *DIE = dyn_cast<CXXDefaultInitExpr>(init))
     init = DIE->getExpr();
 
   // If we're emitting a value with lifetime, we have to do the
   // initialization *before* we leave the cleanup scopes.
-  if (const ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(init))
-    init = EWC->getSubExpr();
+  if (auto *EWC = dyn_cast<ExprWithCleanups>(init)) {
     CodeGenFunction::RunCleanupsScope Scope(*this);
+    return EmitScalarInit(EWC->getSubExpr(), D, lvalue, capturedByInit);
+  }
 
   // We have to maintain the illusion that the variable is
   // zero-initialized.  If the variable might be accessed in its
   // initializer, zero-initialize before running the initializer, then
   // actually perform the initialization with an assign.
   bool accessedByInit = false;
   if (lifetime != Qualifiers::OCL_ExplicitNone)
     accessedByInit = (capturedByInit || isAccessedBy(D, init));

clang/test/CodeGenObjCXX/arc-blocks.mm

void foo1() {
   // destructor.
   TrivialInternal t5;
   ^{ (void)t0; (void)t1; (void)t2; (void)t3; (void)t4; (void)t5; };
 }
 }
 
 // Test that calls to @llvm.objc.retainBlock aren't emitted in some cases.
 
-namespace test_block_retain {
-  typedef void (^BlockTy)();
-
-  void foo1(id);
 
+namespace test_block_retain {
+
 // CHECK-LABEL: define{{.*}} void @_ZN17test_block_retain14initializationEP11objc_object(
 // CHECK-NOT: @llvm.objc.retainBlock(
   void initialization(id a) {
     BlockTy b0 = ^{ foo1(a); };
     BlockTy b1 = (^{ foo1(a); });
     b0();
     b1();
   }

 // CHECK: %[[V8:.*]] = bitcast void ()* %[[V7]] to i8*
 // CHECK: store i8* %[[V8]], i8** %[[B1]], align 8
   void assignmentObjCPtr(id a) {
     BlockTy b0 = ^{ foo1(a); };
     id b1;
     b1 = b0;
     ((BlockTy)b1)();
   }
   }
+
+  // Check that the block capture is released after the full expression.
+
+  // CHECK-LABEL: define void @_ZN13test_rval_ref4testEP11objc_object(
+  // CHECK: %[[BLOCK:.*]] = alloca <{ i8*, i32, i32, i8*, %[[STRUCT_BLOCK_DESCRIPTOR]]*, i8* }>, align 8
+  // CHECK: %[[BLOCK_CAPTURED:.*]] = getelementptr inbounds <{ i8*, i32, i32, i8*, %[[STRUCT_BLOCK_DESCRIPTOR]]*, i8* }>, <{ i8*, i32, i32, i8*, %[[STRUCT_BLOCK_DESCRIPTOR]]*, i8* }>* %[[BLOCK]], i32 0, i32 5
+  // CHECK: %[[V1:.*]] = call i8* @llvm.objc.retain(
+  // CHECK: store i8* %[[V1]], i8** %[[BLOCK_CAPTURED]], align 8
+  // CHECK: invoke void @_ZN13test_rval_ref17callTemplateBlockEOU15__autoreleasingU13block_pointerFvvE(
+
+  // CHECK: call void @llvm.objc.storeStrong(i8** %[[BLOCK_CAPTURED]], i8* null)
+
+  namespace test_rval_ref {
+  void callTemplateBlock(BlockTy &&func);
+
+  void test(id str) {
+    return callTemplateBlock(^void() {
+      foo1(str);
+    });
+  }
+  }

clang/test/CodeGenObjCXX/arc.mm

void test41(__weak id &&x) {
   __weak id y = static_cast<__weak id &&>(x);
 }
 // CHECK-LABEL: define{{.*}} void @_Z6test41OU6__weakP11objc_object
 // CHECK:      [[X:%.*]] = alloca i8**
 // CHECK:      [[Y:%.*]] = alloca i8*
 // CHECK:      [[T0:%.*]] = load i8**, i8*** [[X]]
 // CHECK-NEXT: call void @llvm.objc.moveWeak(i8** [[Y]], i8** [[T0]])
 // CHECK-NEXT: call void @llvm.objc.destroyWeak(i8** [[Y]])
+
+void test42() {
+  __attribute__((ns_returns_retained)) id test42_0();
+  id test42_1(id);
+  void test42_2(id &&);
+  test42_2(test42_1(test42_0()));
+}
+
+// Check that the pointer returned by test42_0 is released after the full expression.
+
+// CHECK-LABEL: define void @_Z6test42v()
+// CHECK: %[[CALL:.*]] = call i8* @_Z8test42_0v()
+// CHECK: call void @_Z8test42_2OU15__autoreleasingP11objc_object(
+// CHECK: call void @llvm.objc.release(i8* %[[CALL]])