[PATCH] D70935: [CodeGen][ObjC] Emit a primitive store to store a __strong field in ExpandTypeFromArgs

[Akira Hatanaka via Phabricator via cfe-commits]

ahatanak created this revision.
ahatanak added a reviewer: rjmccall.
ahatanak added a project: clang.
Herald added subscribers: ributzka, dexonsmith, jkorous.

This fixes a bug in IRGen where a call to `llvm.objc.storeStrong` was being emitted to initialize a __strong field of an uninitialized temporary struct, which caused crashes at runtime.
rdar://problem/51807365


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D70935

Files:
  clang/lib/CodeGen/CGCall.cpp
  clang/test/CodeGenObjC/nontrivial-struct-param-init.m


Index: clang/test/CodeGenObjC/nontrivial-struct-param-init.m
===================================================================
--- /dev/null
+++ clang/test/CodeGenObjC/nontrivial-struct-param-init.m
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -triple i386-apple-watchos6.0-simulator -emit-llvm -fblocks -fobjc-arc -o - %s | FileCheck %s
+
+// CHECK: %[[STRUCT_S:.*]] = type { i8* }
+
+typedef struct {
+  id x;
+} S;
+
+// CHECK: define void @test0(i8* %[[A_0:.*]])
+// CHECK: %[[A:.*]] = alloca %[[STRUCT_S]], align 4
+// CHECK: %[[X:.*]] = getelementptr inbounds %[[STRUCT_S]], %[[STRUCT_S]]* %[[A]], i32 0, i32 0
+// CHECK: store i8* %[[A_0]], i8** %[[X]], align 4
+// CHECK: %[[V0:.*]] = bitcast %[[STRUCT_S]]* %[[A]] to i8**
+// CHECK: call void @__destructor_4_s0(i8** %[[V0]]) #2
+
+void test0(S a) {
+}
Index: clang/lib/CodeGen/CGCall.cpp
===================================================================
--- clang/lib/CodeGen/CGCall.cpp
+++ clang/lib/CodeGen/CGCall.cpp
@@ -1048,7 +1048,12 @@
     EmitStoreOfComplex(ComplexPairTy(realValue, imagValue), LV, /*init*/ true);
   } else {
     assert(isa<NoExpansion>(Exp.get()));
-    EmitStoreThroughLValue(RValue::get(*AI++), LV);
+    if (LV.getQuals().getObjCLifetime()) {
+      assert(LV.getQuals().getObjCLifetime() == Qualifiers::OCL_Strong &&
+             "pointer to __strong expected");
+      EmitStoreOfScalar(*AI++, LV);
+    } else
+      EmitStoreThroughLValue(RValue::get(*AI++), LV);
   }
 }
 


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