clang/test/CodeGenCXX/thiscall-struct-return.cpp

   1 // For MSVC ABI compatibility, all structures returned by value using the
   2 // thiscall calling convention must use the hidden parameter.
   3 //
   4 // RUN: %clang_cc1 -triple i386-PC-Win32 %s -fms-compatibility -emit-llvm -o - | FileCheck %s
   5
   6 // This structure would normally be returned via EAX
   7 struct S {
   8   int i;
   9 };
  10
  11 // This structure would normally be returned via EAX/EDX
  12 struct M {
  13   int i;
  14   int j;
  15 };
  16
  17 class C {
  18 public:
  19   C() {}
  20
  21   struct S __attribute__((thiscall)) Small() const {
  22     struct S s = { 0 };
  23     return s;
  24   }
  25
  26   struct M __attribute__((thiscall)) Medium() const {
  27     struct M m = { 0 };
  28     return m;
  29   }
  30 };
  31
  32 // CHECK-LABEL: define{{.*}} void @_Z4testv()
  33 void test( void ) {
  34 // CHECK: call void @_ZN1CC1Ev(%class.C* {{[^,]*}} [[C:%.+]])
  35   C c;
  36
  37 // CHECK: call x86_thiscallcc void @_ZNK1C5SmallEv(%struct.S* sret(%struct.S) align 4 %{{.+}}, %class.C* {{[^,]*}} [[C]])
  38   (void)c.Small();
  39 // CHECK: call x86_thiscallcc void @_ZNK1C6MediumEv(%struct.M* sret(%struct.M) align 4 %{{.+}}, %class.C* {{[^,]*}} [[C]])
  40   (void)c.Medium();
  41 }