clang/test/CodeGenCXX/msvc-global-delete-scalar-array-split.cpp

// RUN: %clang_cc1 -emit-llvm -fms-extensions %s -triple=x86_64-pc-windows-msvc -o - | FileCheck %s

// Scalar `operator delete` and array `operator delete[]` use DISTINCT global
// delete wrappers even though their mangled signatures are otherwise identical
// (both YAXPEAX_K@Z): __global_delete for scalar, __global_array_delete for
// array. Conflating them would forward one path to the wrong global operator
// delete. This matches MSVC (validated against cl.exe 19.44), which likewise
// uses __global_delete vs __global_array_delete and shares one empty fallback.

using sz = decltype(sizeof(0));

// Member scalar operator delete -> its deleting destructor's global path uses
// __global_delete.
struct Scalar {
  void *operator new(sz);
  void operator delete(void *, sz);
  virtual ~Scalar();
};
struct ScalarD : Scalar {
  virtual ~ScalarD();
};
Scalar::~Scalar() {}
ScalarD::~ScalarD() {}

// Member array operator delete[] -> its vector deleting destructor's global
// path uses __global_array_delete.
struct Array {
  void *operator new[](sz);
  void operator delete[](void *, sz);
  virtual ~Array();
};
struct ArrayD : Array {
  virtual ~ArrayD();
};
Array::~Array() {}
ArrayD::~ArrayD() {}

// ::delete on class types with non-trivial destructors triggers the forwarding
// bodies for both wrappers.
void test() {
  ::delete new ScalarD();
  ArrayD *a = new ArrayD[2];
  ::delete[] a;
}

// The shared __empty_global_delete fallback is emitted with a trapping body
// (kept alive via llvm.used) even though both wrappers have real forwarding
// bodies here.
// CHECK: define linkonce_odr void @"?__empty_global_delete@@YAXPEAX_K@Z"(ptr noundef %0, i64 noundef %1)
// CHECK-NEXT: call void @llvm.trap()

// The scalar deleting destructor's global path calls __global_delete.
// CHECK: call void @"?__global_delete@@YAXPEAX_K@Z"(

// The vector deleting destructor's global array path calls __global_array_delete.
// CHECK: call void @"?__global_array_delete@@YAXPEAX_K@Z"(

// The forwarding bodies are emitted at end-of-module. Each wrapper forwards to
// its OWN global operator delete: __global_delete to the scalar ??3@,
// __global_array_delete to the array ??_V@.
// CHECK: define linkonce_odr void @"?__global_delete@@YAXPEAX_K@Z"(ptr noundef %0, i64 noundef %1)
// CHECK-NEXT: call void @"??3@YAXPEAX_K@Z"(ptr %0, i64 %1)
// CHECK: define linkonce_odr void @"?__global_array_delete@@YAXPEAX_K@Z"(ptr noundef %0, i64 noundef %1)
// CHECK-NEXT: call void @"??_V@YAXPEAX_K@Z"(ptr %0, i64 %1)