clang/test/CodeGenCXX/return.cpp

   1 // RUN: %clang_cc1 -emit-llvm -triple %itanium_abi_triple -std=c++11 -o - %s | FileCheck --check-prefixes=CHECK,CHECK-COMMON %s
   2 // RUN: %clang_cc1 -emit-llvm -triple %itanium_abi_triple -std=c++11 -O -o - %s | FileCheck %s --check-prefixes=CHECK-OPT,CHECK-COMMON
   3 // RUN: %clang_cc1 -emit-llvm -triple %itanium_abi_triple -std=c++11 -fno-strict-return -o - %s | FileCheck %s --check-prefixes=CHECK-NOSTRICT,CHECK-COMMON
   4 // RUN: %clang_cc1 -emit-llvm -triple %itanium_abi_triple -std=c++11 -fno-strict-return -Wno-return-type -o - %s | FileCheck %s --check-prefixes=CHECK-NOSTRICT,CHECK-COMMON
   5 // RUN: %clang_cc1 -emit-llvm -triple %itanium_abi_triple -std=c++11 -fno-strict-return -O -o - %s | FileCheck %s --check-prefixes=CHECK-NOSTRICT-OPT,CHECK-COMMON
   6
   7 // CHECK-COMMON-LABEL: @_Z9no_return
   8 int no_return() {
   9   // CHECK:      call void @llvm.trap
  10   // CHECK-NEXT: unreachable
  11
  12   // CHECK-OPT-NOT: call void @llvm.trap
  13   // CHECK-OPT:     unreachable
  14
  15   // -fno-strict-return should not emit trap + unreachable but it should return
  16   // an undefined value instead.
  17
  18   // CHECK-NOSTRICT: alloca
  19   // CHECK-NOSTRICT-NEXT: load
  20   // CHECK-NOSTRICT-NEXT: ret i32
  21   // CHECK-NOSTRICT-NEXT: }
  22
  23   // CHECK-NOSTRICT-OPT: ret i32 undef
  24 }
  25
  26 enum Enum {
  27   A, B
  28 };
  29
  30 // CHECK-COMMON-LABEL: @_Z27returnNotViableDontOptimize4Enum
  31 int returnNotViableDontOptimize(Enum e) {
  32   switch (e) {
  33   case A: return 1;
  34   case B: return 2;
  35   }
  36   // Undefined behaviour optimization shouldn't be used when -fno-strict-return
  37   // is turned on, even if all the enum cases are covered in this function.
  38
  39   // CHECK-NOSTRICT-NOT: call void @llvm.trap
  40   // CHECK-NOSTRICT-NOT: unreachable
  41 }
  42
  43 struct Trivial {
  44   int x;
  45 };
  46
  47 // CHECK-NOSTRICT-LABEL: @_Z7trivialv
  48 Trivial trivial() {
  49   // This function returns a trivial record so -fno-strict-return should avoid
  50   // the undefined behaviour optimization.
  51
  52   // CHECK-NOSTRICT-NOT: call void @llvm.trap
  53   // CHECK-NOSTRICT-NOT: unreachable
  54 }
  55
  56 struct NonTrivialCopy {
  57   NonTrivialCopy(const NonTrivialCopy &);
  58 };
  59
  60 // CHECK-NOSTRICT-LABEL: @_Z14nonTrivialCopyv
  61 NonTrivialCopy nonTrivialCopy() {
  62   // CHECK-NOSTRICT-NOT: call void @llvm.trap
  63   // CHECK-NOSTRICT-NOT: unreachable
  64 }
  65
  66 struct NonTrivialDefaultConstructor {
  67   int x;
  68
  69   NonTrivialDefaultConstructor() { }
  70 };
  71
  72 // CHECK-NOSTRICT-LABEL: @_Z28nonTrivialDefaultConstructorv
  73 NonTrivialDefaultConstructor nonTrivialDefaultConstructor() {
  74   // CHECK-NOSTRICT-NOT: call void @llvm.trap
  75   // CHECK-NOSTRICT-NOT: unreachable
  76 }
  77
  78 // Functions that return records with non-trivial destructors should always use
  79 // the -fstrict-return optimization.
  80
  81 struct NonTrivialDestructor {
  82   ~NonTrivialDestructor();
  83 };
  84
  85 // CHECK-NOSTRICT-LABEL: @_Z20nonTrivialDestructorv
  86 NonTrivialDestructor nonTrivialDestructor() {
  87   // CHECK-NOSTRICT: call void @llvm.trap
  88   // CHECK-NOSTRICT-NEXT: unreachable
  89 }
  90
  91 // The behavior for lambdas should be identical to functions.
  92 // CHECK-COMMON-LABEL: @_Z10lambdaTestv
  93 void lambdaTest() {
  94   auto lambda1 = []() -> int {
  95   };
  96   lambda1();
  97
  98   // CHECK: call void @llvm.trap
  99   // CHECK-NEXT: unreachable
 100
 101   // CHECK-NOSTRICT-NOT: call void @llvm.trap
 102   // CHECK-NOSTRICT-NOT: unreachable
 103 }