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llvm-project/clang/test/CodeGenObjC/weak-in-c-struct.m
Aiden Grossman e2d7cd685d
[IR] Make dead_on_return attribute optionally sized 
This patch makes the dead_on_return parameter attribute optionally require a number
of bytes to be passed in to specify the number of bytes known to be dead
upon function return/unwind. This is aimed at enabling annotating the
this pointer in C++ destructors with dead_on_return in clang. We need
this to handle cases like the following:

```
struct X {
  int n;
  ~X() {
    this[n].n = 0;
  }
};
void f() {
  X xs[] = {42, -1};
}
```

Where we only certain that sizeof(X) bytes are dead upon return of ~X.
Otherwise DSE would be able to eliminate the store in ~X which would not
be correct.

This patch only does the wiring within IR. Future patches will make
clang emit correct sizing information and update DSE to only delete
stores to objects marked dead_on_return that are provably in bounds of
the number of bytes specified to be dead_on_return.

Reviewers: nikic, alinas, antoniofrighetto

Pull Request: https://github.com/llvm/llvm-project/pull/171712
2026-01-21 08:22:05 -08:00

176 lines
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// RUN: %clang_cc1 -triple arm64-apple-ios11 -fobjc-arc -fblocks -fobjc-runtime=ios-11.0 -emit-llvm -o - %s | FileCheck -check-prefix=ARM64 -check-prefix=COMMON %s
// RUN: %clang_cc1 -triple thumbv7-apple-ios10 -fobjc-arc -fblocks -fobjc-runtime=ios-10.0 -emit-llvm -o - %s | FileCheck -check-prefix=COMMON %s
// RUN: %clang_cc1 -triple x86_64-apple-macosx10.13 -fobjc-arc -fblocks -fobjc-runtime=macosx-10.13.0 -emit-llvm -o - %s | FileCheck -check-prefix=COMMON %s
// RUN: %clang_cc1 -triple i386-apple-macosx10.13.0 -fobjc-arc -fblocks -fobjc-runtime=macosx-fragile-10.13.0 -emit-llvm -o - %s | FileCheck -check-prefix=COMMON %s
typedef void (^BlockTy)(void);
// COMMON: %[[STRUCT_WEAK:.*]] = type { i32, ptr }
typedef struct {
int f0;
__weak id f1;
} Weak;
Weak getWeak(void);
void calleeWeak(Weak);
// ARM64: define{{.*}} void @test_constructor_destructor_Weak()
// ARM64: %[[T:.*]] = alloca %[[STRUCT_WEAK]], align 8
// ARM64: call void @__default_constructor_8_w8(ptr %[[T]])
// ARM64: call void @__destructor_8_w8(ptr %[[T]])
// ARM64: ret void
// ARM64: define linkonce_odr hidden void @__default_constructor_8_w8(ptr noundef %[[DST:.*]])
// ARM64: %[[DST_ADDR:.*]] = alloca ptr, align 8
// ARM64: store ptr %[[DST]], ptr %[[DST_ADDR]], align 8
// ARM64: %[[V0:.*]] = load ptr, ptr %[[DST_ADDR]], align 8
// ARM64: %[[V2:.*]] = getelementptr inbounds i8, ptr %[[V0]], i64 8
// ARM64: call void @llvm.memset.p0.i64(ptr align 8 %[[V2]], i8 0, i64 8, i1 false)
// ARM64: define linkonce_odr hidden void @__destructor_8_w8(ptr noundef %[[DST:.*]])
// ARM64: %[[DST_ADDR:.*]] = alloca ptr, align 8
// ARM64: store ptr %[[DST]], ptr %[[DST_ADDR]], align 8
// ARM64: %[[V0:.*]] = load ptr, ptr %[[DST_ADDR]], align 8
// ARM64: %[[V2:.*]] = getelementptr inbounds i8, ptr %[[V0]], i64 8
// ARM64: call void @llvm.objc.destroyWeak(ptr %[[V2]])
@interface C
- (void)m:(Weak)a;
@end
void test_constructor_destructor_Weak(void) {
Weak t;
}
// ARM64: define{{.*}} void @test_copy_constructor_Weak(ptr noundef %{{.*}})
// ARM64: call void @__copy_constructor_8_8_t0w4_w8(ptr %{{.*}}, ptr %{{.*}})
// ARM64: call void @__destructor_8_w8(ptr %{{.*}})
// ARM64: define linkonce_odr hidden void @__copy_constructor_8_8_t0w4_w8(ptr noundef %[[DST:.*]], ptr noundef %[[SRC:.*]])
// ARM64: %[[DST_ADDR:.*]] = alloca ptr, align 8
// ARM64: %[[SRC_ADDR:.*]] = alloca ptr, align 8
// ARM64: store ptr %[[DST]], ptr %[[DST_ADDR]], align 8
// ARM64: store ptr %[[SRC]], ptr %[[SRC_ADDR]], align 8
// ARM64: %[[V0:.*]] = load ptr, ptr %[[DST_ADDR]], align 8
// ARM64: %[[V1:.*]] = load ptr, ptr %[[SRC_ADDR]], align 8
// ARM64: %[[V4:.*]] = load i32, ptr %[[V1]], align 8
// ARM64: store i32 %[[V4]], ptr %[[V0]], align 8
// ARM64: %[[V6:.*]] = getelementptr inbounds i8, ptr %[[V0]], i64 8
// ARM64: %[[V9:.*]] = getelementptr inbounds i8, ptr %[[V1]], i64 8
// ARM64: call void @llvm.objc.copyWeak(ptr %[[V6]], ptr %[[V9]])
void test_copy_constructor_Weak(Weak *s) {
Weak t = *s;
}
// ARM64: define{{.*}} void @test_copy_assignment_Weak(ptr noundef %{{.*}}, ptr noundef %{{.*}})
// ARM64: call void @__copy_assignment_8_8_t0w4_w8(ptr %{{.*}}, ptr %{{.*}})
// ARM64: define linkonce_odr hidden void @__copy_assignment_8_8_t0w4_w8(ptr noundef %[[DST:.*]], ptr noundef %[[SRC:.*]])
// ARM64: %[[DST_ADDR:.*]] = alloca ptr, align 8
// ARM64: %[[SRC_ADDR:.*]] = alloca ptr, align 8
// ARM64: store ptr %[[DST]], ptr %[[DST_ADDR]], align 8
// ARM64: store ptr %[[SRC]], ptr %[[SRC_ADDR]], align 8
// ARM64: %[[V0:.*]] = load ptr, ptr %[[DST_ADDR]], align 8
// ARM64: %[[V1:.*]] = load ptr, ptr %[[SRC_ADDR]], align 8
// ARM64: %[[V4:.*]] = load i32, ptr %[[V1]], align 8
// ARM64: store i32 %[[V4]], ptr %[[V0]], align 8
// ARM64: %[[V6:.*]] = getelementptr inbounds i8, ptr %[[V0]], i64 8
// ARM64: %[[V9:.*]] = getelementptr inbounds i8, ptr %[[V1]], i64 8
// ARM64: %[[V11:.*]] = call ptr @llvm.objc.loadWeakRetained(ptr %[[V9]])
// ARM64: %[[V12:.*]] = call ptr @llvm.objc.storeWeak(ptr %[[V6]], ptr %[[V11]])
// ARM64: call void @llvm.objc.release(ptr %[[V11]])
void test_copy_assignment_Weak(Weak *d, Weak *s) {
*d = *s;
}
// ARM64: define internal void @__Block_byref_object_copy_(ptr noundef %0, ptr noundef %1)
// ARM64: call void @__move_constructor_8_8_t0w4_w8(ptr %{{.*}}, ptr %{{.*}})
// ARM64: define linkonce_odr hidden void @__move_constructor_8_8_t0w4_w8(ptr noundef %[[DST:.*]], ptr noundef %[[SRC:.*]])
// ARM64: %[[DST_ADDR:.*]] = alloca ptr, align 8
// ARM64: %[[SRC_ADDR:.*]] = alloca ptr, align 8
// ARM64: store ptr %[[DST]], ptr %[[DST_ADDR]], align 8
// ARM64: store ptr %[[SRC]], ptr %[[SRC_ADDR]], align 8
// ARM64: %[[V0:.*]] = load ptr, ptr %[[DST_ADDR]], align 8
// ARM64: %[[V1:.*]] = load ptr, ptr %[[SRC_ADDR]], align 8
// ARM64: %[[V4:.*]] = load i32, ptr %[[V1]], align 8
// ARM64: store i32 %[[V4]], ptr %[[V0]], align 8
// ARM64: %[[V6:.*]] = getelementptr inbounds i8, ptr %[[V0]], i64 8
// ARM64: %[[V9:.*]] = getelementptr inbounds i8, ptr %[[V1]], i64 8
// ARM64: call void @llvm.objc.moveWeak(ptr %[[V6]], ptr %[[V9]])
void test_move_constructor_Weak(void) {
__block Weak t;
BlockTy b = ^{ (void)t; };
}
// ARM64: define{{.*}} void @test_move_assignment_Weak(ptr noundef %{{.*}})
// ARM64: call void @__move_assignment_8_8_t0w4_w8(ptr %{{.*}}, ptr %{{.*}})
// ARM64: define linkonce_odr hidden void @__move_assignment_8_8_t0w4_w8(ptr noundef %[[DST:.*]], ptr noundef %[[SRC:.*]])
// ARM64: %[[DST_ADDR:.*]] = alloca ptr, align 8
// ARM64: %[[SRC_ADDR:.*]] = alloca ptr, align 8
// ARM64: store ptr %[[DST]], ptr %[[DST_ADDR]], align 8
// ARM64: store ptr %[[SRC]], ptr %[[SRC_ADDR]], align 8
// ARM64: %[[V0:.*]] = load ptr, ptr %[[DST_ADDR]], align 8
// ARM64: %[[V1:.*]] = load ptr, ptr %[[SRC_ADDR]], align 8
// ARM64: %[[V4:.*]] = load i32, ptr %[[V1]], align 8
// ARM64: store i32 %[[V4]], ptr %[[V0]], align 8
// ARM64: %[[V6:.*]] = getelementptr inbounds i8, ptr %[[V0]], i64 8
// ARM64: %[[V9:.*]] = getelementptr inbounds i8, ptr %[[V1]], i64 8
// ARM64: %[[V11:.*]] = call ptr @llvm.objc.loadWeakRetained(ptr %[[V9]])
// ARM64: %[[V12:.*]] = call ptr @llvm.objc.storeWeak(ptr %[[V6]], ptr %[[V11]])
// ARM64: call void @llvm.objc.destroyWeak(ptr %[[V9]])
// ARM64: call void @llvm.objc.release(ptr %[[V11]])
void test_move_assignment_Weak(Weak *p) {
*p = getWeak();
}
// COMMON: define{{.*}} void @test_parameter_Weak(ptr noundef dead_on_return %[[A:.*]])
// COMMON: call void @__destructor_{{.*}}(ptr %[[A]])
void test_parameter_Weak(Weak a) {
}
// COMMON: define{{.*}} void @test_argument_Weak(ptr noundef %[[A:.*]])
// COMMON: %[[A_ADDR:.*]] = alloca ptr
// COMMON: %[[AGG_TMP:.*]] = alloca %[[STRUCT_WEAK]]
// COMMON: store ptr %[[A]], ptr %[[A_ADDR]]
// COMMON: %[[V0:.*]] = load ptr, ptr %[[A_ADDR]]
// COMMON: call void @__copy_constructor_{{.*}}(ptr %[[AGG_TMP]], ptr %[[V0]])
// COMMON: call void @calleeWeak(ptr noundef dead_on_return %[[AGG_TMP]])
// COMMON-NEXT: ret
void test_argument_Weak(Weak *a) {
calleeWeak(*a);
}
// COMMON: define{{.*}} void @test_return_Weak(ptr dead_on_unwind noalias writable sret(%[[STRUCT_WEAK]]) align {{.*}} %[[AGG_RESULT:.*]], ptr noundef %[[A:.*]])
// COMMON: %[[A_ADDR:.*]] = alloca ptr
// COMMON: store ptr %[[A]], ptr %[[A_ADDR]]
// COMMON: %[[V0:.*]] = load ptr, ptr %[[A_ADDR]]
// COMMON: call void @__copy_constructor_{{.*}}(ptr %[[AGG_RESULT]], ptr %[[V0]])
// COMMON: ret void
Weak test_return_Weak(Weak *a) {
return *a;
}
// COMMON-LABEL: define{{.*}} void @test_null_receiver(
// COMMON: %[[AGG_TMP:.*]] = alloca %[[STRUCT_WEAK]]
// COMMON: br i1
// COMMON: call void @objc_msgSend({{.*}}, ptr noundef dead_on_return %[[AGG_TMP]])
// COMMON: br
// COMMON: call void @__destructor_{{.*}}(ptr %[[AGG_TMP]])
// COMMON: br
void test_null_receiver(C *c) {
[c m:getWeak()];
}
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