test/CodeGenCXX/nrvo.cpp

   1 // RUN: %clang_cc1 -emit-llvm -O1 -o - %s | FileCheck %s
   2 // RUN: %clang_cc1 -emit-llvm -O1 -fexceptions -o - %s | FileCheck --check-prefix=CHECK-EH %s
   3
   4 // Test code generation for the named return value optimization.
   5 class X {
   6 public:
   7   X();
   8   X(const X&);
   9   ~X();
  10 };
  11
  12 // CHECK: define void @_Z5test0v
  13 // CHECK-EH: define void @_Z5test0v
  14 X test0() {
  15   X x;
  16   // CHECK:          call void @_ZN1XC1Ev
  17   // CHECK-NEXT:     ret void
  18
  19   // CHECK-EH:       call void @_ZN1XC1Ev
  20   // CHECK-EH-NEXT:  ret void
  21   return x;
  22 }
  23
  24 // CHECK: define void @_Z5test1b(
  25 // CHECK-EH: define void @_Z5test1b(
  26 X test1(bool B) {
  27   // CHECK:      tail call void @_ZN1XC1Ev
  28   // CHECK-NEXT: ret void
  29   X x;
  30   if (B)
  31     return (x);
  32   return x;
  33   // CHECK-EH:      tail call void @_ZN1XC1Ev
  34   // CHECK-EH-NEXT: ret void
  35 }
  36
  37 // CHECK: define void @_Z5test2b
  38 // CHECK-EH: define void @_Z5test2b
  39 X test2(bool B) {
  40   // No NRVO.
  41
  42   X x;
  43   X y;
  44   if (B)
  45     return y;
  46   return x;
  47
  48   // CHECK: call void @_ZN1XC1Ev
  49   // CHECK-NEXT: call void @_ZN1XC1Ev
  50   // CHECK: call void @_ZN1XC1ERKS_
  51   // CHECK: call void @_ZN1XC1ERKS_
  52   // CHECK: call void @_ZN1XD1Ev
  53   // CHECK: call void @_ZN1XD1Ev
  54   // CHECK: ret void
  55
  56   // The block ordering in the -fexceptions IR is unfortunate.
  57
  58   // CHECK-EH:      call void @_ZN1XC1Ev
  59   // CHECK-EH-NEXT: invoke void @_ZN1XC1Ev
  60   // -> %invoke.cont, %lpad
  61
  62   // %invoke.cont:
  63   // CHECK-EH:      br i1
  64   // -> %if.then, %if.end
  65
  66   // %if.then: returning 'x'
  67   // CHECK-EH:      invoke void @_ZN1XC1ERKS_
  68   // -> %cleanup, %lpad1
  69
  70   // %lpad: landing pad for ctor of 'y', dtor of 'y'
  71   // CHECK-EH:      call i8* @llvm.eh.exception()
  72   // CHECK-EH: call i32 (i8*, i8*, ...)* @llvm.eh.selector
  73   // CHECK-EH-NEXT: br label
  74   // -> %eh.cleanup
  75
  76   // %lpad1: landing pad for return copy ctors, EH cleanup for 'y'
  77   // CHECK-EH: invoke void @_ZN1XD1Ev
  78   // -> %eh.cleanup, %terminate.lpad
  79
  80   // %if.end: returning 'y'
  81   // CHECK-EH: invoke void @_ZN1XC1ERKS_
  82   // -> %cleanup, %lpad1
  83
  84   // %cleanup: normal cleanup for 'y'
  85   // CHECK-EH: invoke void @_ZN1XD1Ev
  86   // -> %invoke.cont11, %lpad
  87
  88   // %invoke.cont11: normal cleanup for 'x'
  89   // CHECK-EH:      call void @_ZN1XD1Ev
  90   // CHECK-EH-NEXT: ret void
  91
  92   // %eh.cleanup:  EH cleanup for 'x'
  93   // CHECK-EH: invoke void @_ZN1XD1Ev
  94   // -> %invoke.cont17, %terminate.lpad
  95
  96   // %invoke.cont17: rethrow block for %eh.cleanup.
  97   // This really should be elsewhere in the function.
  98   // CHECK-EH:      call void @_Unwind_Resume_or_Rethrow
  99   // CHECK-EH-NEXT: unreachable
 100
 101   // %terminate.lpad: terminate landing pad.
 102   // CHECK-EH:      call i8* @llvm.eh.exception()
 103   // CHECK-EH-NEXT: call i32 (i8*, i8*, ...)* @llvm.eh.selector
 104   // CHECK-EH-NEXT: call void @_ZSt9terminatev()
 105   // CHECK-EH-NEXT: unreachable
 106
 107 }
 108
 109 X test3(bool B) {
 110   // FIXME: We don't manage to apply NRVO here, although we could.
 111   {
 112     X y;
 113     return y;
 114   }
 115   X x;
 116   return x;
 117 }
 118
 119 extern "C" void exit(int) throw();
 120
 121 // CHECK: define void @_Z5test4b
 122 X test4(bool B) {
 123   {
 124     // CHECK: tail call void @_ZN1XC1Ev
 125     X x;
 126     // CHECK: br i1
 127     if (B)
 128       return x;
 129   }
 130   // CHECK: tail call void @_ZN1XD1Ev
 131   // CHECK: tail call void @exit(i32 1)
 132   exit(1);
 133 }