clang/test/CodeGen/AArch64/args.cpp

   1 // RUN: %clang_cc1 -triple arm64-apple-ios7.0 -target-abi darwinpcs -emit-llvm -o - %s | FileCheck %s
   2 // RUN: %clang_cc1 -triple aarch64-linux-gnu -emit-llvm -o - -x c %s | FileCheck %s --check-prefix=CHECK-GNU-C
   3 // RUN: %clang_cc1 -triple aarch64-linux-gnu -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-GNU-CXX
   4
   5 // Empty structs are ignored for PCS purposes on Darwin and in C mode elsewhere.
   6 // In C++ mode on ELF they consume a register slot though. Functions are
   7 // slightly bigger than minimal to make confirmation against actual GCC
   8 // behaviour easier.
   9
  10 #if __cplusplus
  11 #define EXTERNC extern "C"
  12 #else
  13 #define EXTERNC
  14 #endif
  15
  16 struct Empty {};
  17
  18 // CHECK: define{{.*}} i32 @empty_arg(i32 noundef %a)
  19 // CHECK-GNU-C: define{{.*}} i32 @empty_arg(i32 noundef %a)
  20 // CHECK-GNU-CXX: define{{.*}} i32 @empty_arg(i8 %e.coerce, i32 noundef %a)
  21 EXTERNC int empty_arg(struct Empty e, int a) {
  22   return a;
  23 }
  24
  25 // CHECK: define{{.*}} void @empty_ret()
  26 // CHECK-GNU-C: define{{.*}} void @empty_ret()
  27 // CHECK-GNU-CXX: define{{.*}} void @empty_ret()
  28 EXTERNC struct Empty empty_ret(void) {
  29   struct Empty e;
  30   return e;
  31 }
  32
  33 // However, what counts as "empty" is a baroque mess. This is super-empty, it's
  34 // ignored even in C++ mode. It also has sizeof == 0, violating C++, but that's
  35 // legacy for you:
  36
  37 struct SuperEmpty {
  38   int arr[0];
  39 };
  40
  41 // CHECK: define{{.*}} i32 @super_empty_arg(i32 noundef %a)
  42 // CHECK-GNU-C: define{{.*}} i32 @super_empty_arg(i32 noundef %a)
  43 // CHECK-GNU-CXX: define{{.*}} i32 @super_empty_arg(i32 noundef %a)
  44 EXTERNC int super_empty_arg(struct SuperEmpty e, int a) {
  45   return a;
  46 }
  47
  48 // This is not empty. It has 0 size but consumes a register slot for GCC.
  49
  50 struct SortOfEmpty {
  51   struct SuperEmpty e;
  52 };
  53
  54 // CHECK: define{{.*}} i32 @sort_of_empty_arg(i32 noundef %a)
  55 // CHECK-GNU-C: define{{.*}} i32 @sort_of_empty_arg(i32 noundef %a)
  56 // CHECK-GNU-CXX: define{{.*}} i32 @sort_of_empty_arg(i8 %e.coerce, i32 noundef %a)
  57 EXTERNC int sort_of_empty_arg(struct Empty e, int a) {
  58   return a;
  59 }
  60
  61 // CHECK: define{{.*}} void @sort_of_empty_ret()
  62 // CHECK-GNU-C: define{{.*}} void @sort_of_empty_ret()
  63 // CHECK-GNU-CXX: define{{.*}} void @sort_of_empty_ret()
  64 EXTERNC struct SortOfEmpty sort_of_empty_ret(void) {
  65   struct SortOfEmpty e;
  66   return e;
  67 }