clang/test/SemaCXX/builtins-overflow.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -std=c++17 -verify %s
   2 // RUN: %clang_cc1 -fsyntax-only -std=c++17 -verify %s -fexperimental-new-constant-interpreter
   3 // expected-no-diagnostics
   4
   5 #include <limits.h>
   6 #include <stdint.h>
   7
   8 int a() {
   9   const int x = 3;
  10   static int z;
  11   constexpr int *y = &z;
  12   return []() { return __builtin_sub_overflow((int)x, (int)x, (int *)y); }();
  13 }
  14 int a2() {
  15   const int x = 3;
  16   static int z;
  17   constexpr int *y = &z;
  18   return []() { return __builtin_sub_overflow(x, x, y); }();
  19 }
  20
  21 template<typename T>
  22 struct Result {
  23   bool B;
  24   T Value;
  25   constexpr bool operator==(const Result<T> &Other) {
  26     return B == Other.B && Value == Other.Value;
  27   }
  28 };
  29
  30
  31 template <typename RET, typename LHS, typename RHS>
  32 constexpr Result<RET> add(LHS &&lhs, RHS &&rhs) {
  33   RET sum{};
  34   return {__builtin_add_overflow(lhs, rhs, &sum), sum};
  35 }
  36
  37 static_assert(add<short>(static_cast<char>(120), static_cast<char>(10)) == Result<short>{false, 130});
  38 static_assert(add<char>(static_cast<short>(120), static_cast<short>(10)) == Result<char>{true, -126});
  39 static_assert(add<unsigned int>(INT_MAX, INT_MAX) == Result<unsigned int>{false, static_cast<unsigned int>(INT_MAX) * 2u});
  40 static_assert(add<int>(static_cast<unsigned int>(INT_MAX), 1u) == Result<int>{true, INT_MIN});
  41
  42 static_assert(add<int>(17, 22) == Result<int>{false, 39});
  43 static_assert(add<int>(INT_MAX - 22, 24) == Result<int>{true, INT_MIN + 1});
  44 static_assert(add<int>(INT_MIN + 22, -23) == Result<int>{true, INT_MAX});
  45
  46 template <typename RET, typename LHS, typename RHS>
  47 constexpr Result<RET> sub(LHS &&lhs, RHS &&rhs) {
  48   RET sum{};
  49   return {__builtin_sub_overflow(lhs, rhs, &sum), sum};
  50 }
  51
  52 static_assert(sub<unsigned char>(static_cast<char>(0),static_cast<char>(1)) == Result<unsigned char>{true, UCHAR_MAX});
  53 static_assert(sub<char>(static_cast<unsigned char>(0),static_cast<unsigned char>(1)) == Result<char>{false, -1});
  54 static_assert(sub<unsigned short>(static_cast<short>(0),static_cast<short>(1)) == Result<unsigned short>{true, USHRT_MAX});
  55 static_assert(sub<uint8_t>(static_cast<uint8_t>(255),static_cast<int>(100)) == Result<uint8_t>{false, 155});
  56
  57 static_assert(sub<int>(17,22) == Result<int>{false, -5});
  58 static_assert(sub<int>(INT_MAX - 22, -23) == Result<int>{true, INT_MIN});
  59 static_assert(sub<int>(INT_MIN + 22, 23) == Result<int>{true, INT_MAX});
  60
  61 template <typename RET, typename LHS, typename RHS>
  62 constexpr Result<RET> mul(LHS &&lhs, RHS &&rhs) {
  63   RET sum{};
  64   return {__builtin_mul_overflow(lhs, rhs, &sum), sum};
  65 }
  66
  67 static_assert(mul<int>(17,22) == Result<int>{false, 374});
  68 static_assert(mul<int>(INT_MAX / 22, 23) == Result<int>{true, -2049870757});
  69 static_assert(mul<int>(INT_MIN / 22, -23) == Result<int>{true, -2049870757});
  70
  71 constexpr Result<int> sadd(int lhs, int rhs) {
  72   int sum{};
  73   return {__builtin_sadd_overflow(lhs, rhs, &sum), sum};
  74 }
  75
  76 static_assert(sadd(17,22) == Result<int>{false, 39});
  77 static_assert(sadd(INT_MAX - 22, 23) == Result<int>{true, INT_MIN});
  78 static_assert(sadd(INT_MIN + 22, -23) == Result<int>{true, INT_MAX});
  79
  80 constexpr Result<int> ssub(int lhs, int rhs) {
  81   int sum{};
  82   return {__builtin_ssub_overflow(lhs, rhs, &sum), sum};
  83 }
  84
  85 static_assert(ssub(17,22) == Result<int>{false, -5});
  86 static_assert(ssub(INT_MAX - 22, -23) == Result<int>{true, INT_MIN});
  87 static_assert(ssub(INT_MIN + 22, 23) == Result<int>{true, INT_MAX});
  88
  89 constexpr Result<int> smul(int lhs, int rhs) {
  90   int sum{};
  91   return {__builtin_smul_overflow(lhs, rhs, &sum), sum};
  92 }
  93
  94 static_assert(smul(17,22) == Result<int>{false, 374});
  95 static_assert(smul(INT_MAX / 22, 23) == Result<int>{true, -2049870757});
  96 static_assert(smul(INT_MIN / 22, -23) == Result<int>{true, -2049870757});
  97
  98 template<typename T>
  99 struct CarryResult {
 100   T CarryOut;
 101   T Value;
 102   constexpr bool operator==(const CarryResult<T> &Other) {
 103     return CarryOut == Other.CarryOut && Value == Other.Value;
 104   }
 105 };
 106
 107 constexpr CarryResult<unsigned char> addcb(unsigned char lhs, unsigned char rhs, unsigned char carry) {
 108   unsigned char carry_out{};
 109   unsigned char sum{};
 110   sum = __builtin_addcb(lhs, rhs, carry, &carry_out);
 111   return {carry_out, sum};
 112 }
 113
 114 static_assert(addcb(120, 10, 0) == CarryResult<unsigned char>{0, 130});
 115 static_assert(addcb(250, 10, 0) == CarryResult<unsigned char>{1, 4});
 116 static_assert(addcb(255, 255, 0) == CarryResult<unsigned char>{1, 254});
 117 static_assert(addcb(255, 255, 1) == CarryResult<unsigned char>{1, 255});
 118 static_assert(addcb(255, 0, 1) == CarryResult<unsigned char>{1, 0});
 119 static_assert(addcb(255, 1, 0) == CarryResult<unsigned char>{1, 0});
 120 static_assert(addcb(255, 1, 1) == CarryResult<unsigned char>{1, 1});
 121 // This is currently supported with the carry still producing a value of 1.
 122 // If support for carry outside of 0-1 is removed, change this test to check
 123 // that it is not supported.
 124 static_assert(addcb(255, 255, 2) == CarryResult<unsigned char>{1, 0});
 125
 126 constexpr CarryResult<unsigned char> subcb(unsigned char lhs, unsigned char rhs, unsigned char carry) {
 127   unsigned char carry_out{};
 128   unsigned char sum{};
 129   sum = __builtin_subcb(lhs, rhs, carry, &carry_out);
 130   return {carry_out, sum};
 131 }
 132
 133 static_assert(subcb(20, 10, 0) == CarryResult<unsigned char>{0, 10});
 134 static_assert(subcb(10, 10, 0) == CarryResult<unsigned char>{0, 0});
 135 static_assert(subcb(10, 15, 0) == CarryResult<unsigned char>{1, 251});
 136 // The carry is subtracted from the result
 137 static_assert(subcb(10, 15, 1) == CarryResult<unsigned char>{1, 250});
 138 static_assert(subcb(0, 0, 1) == CarryResult<unsigned char>{1, 255});
 139 static_assert(subcb(0, 1, 0) == CarryResult<unsigned char>{1, 255});
 140 static_assert(subcb(0, 1, 1) == CarryResult<unsigned char>{1, 254});
 141 static_assert(subcb(0, 255, 0) == CarryResult<unsigned char>{1, 1});
 142 static_assert(subcb(0, 255, 1) == CarryResult<unsigned char>{1, 0});
 143 // This is currently supported with the carry still producing a value of 1.
 144 // If support for carry outside of 0-1 is removed, change this test to check
 145 // that it is not supported.
 146 static_assert(subcb(0, 255, 2) == CarryResult<unsigned char>{1, 255});