clang/test/AST/Interp/shifts.cpp

   1 // RUN: %clang_cc1 -fexperimental-new-constant-interpreter -std=c++20 -verify %s
   2 // RUN: %clang_cc1 -fexperimental-new-constant-interpreter -std=c++17 -verify=cxx17 %s
   3 // RUN: %clang_cc1 -std=c++20 -verify=ref %s
   4 // RUN: %clang_cc1 -std=c++17 -verify=ref-cxx17 %s
   5
   6 #define INT_MIN (~__INT_MAX__)
   7
   8
   9 namespace shifts {
  10   constexpr void test() { // ref-error {{constexpr function never produces a constant expression}} \
  11                           // ref-cxx17-error {{constexpr function never produces a constant expression}} \
  12                           // expected-error {{constexpr function never produces a constant expression}} \
  13                           // cxx17-error {{constexpr function never produces a constant expression}} \
  14
  15     char c; // cxx17-warning {{uninitialized variable}} \
  16             // ref-cxx17-warning {{uninitialized variable}}
  17
  18     c = 0 << 0;
  19     c = 0 << 1;
  20     c = 1 << 0;
  21     c = 1 << -0;
  22     c = 1 >> -0;
  23     c = 1 << -1; // expected-warning {{shift count is negative}} \
  24                  // expected-note {{negative shift count -1}} \
  25                  // cxx17-note {{negative shift count -1}} \
  26                  // cxx17-warning {{shift count is negative}} \
  27                  // ref-warning {{shift count is negative}} \
  28                  // ref-note {{negative shift count -1}} \
  29                  // ref-cxx17-warning {{shift count is negative}} \
  30                  // ref-cxx17-note {{negative shift count -1}}
  31
  32     c = 1 >> -1; // expected-warning {{shift count is negative}} \
  33                  // cxx17-warning {{shift count is negative}} \
  34                  // ref-warning {{shift count is negative}} \
  35                  // ref-cxx17-warning {{shift count is negative}}
  36     c = 1 << (unsigned)-1; // expected-warning {{shift count >= width of type}} \
  37                            // FIXME: 'implicit conversion' warning missing in the new interpreter. \
  38                            // cxx17-warning {{shift count >= width of type}} \
  39                            // ref-warning {{shift count >= width of type}} \
  40                            // ref-warning {{implicit conversion}} \
  41                            // ref-cxx17-warning {{shift count >= width of type}} \
  42                            // ref-cxx17-warning {{implicit conversion}}
  43     c = 1 >> (unsigned)-1; // expected-warning {{shift count >= width of type}} \
  44                            // cxx17-warning {{shift count >= width of type}} \
  45                            // ref-warning {{shift count >= width of type}} \
  46                            // ref-cxx17-warning {{shift count >= width of type}}
  47     c = 1 << c;
  48     c <<= 0;
  49     c >>= 0;
  50     c <<= 1;
  51     c >>= 1;
  52     c <<= -1; // expected-warning {{shift count is negative}} \
  53               // cxx17-warning {{shift count is negative}} \
  54               // ref-warning {{shift count is negative}} \
  55               // ref-cxx17-warning {{shift count is negative}}
  56     c >>= -1; // expected-warning {{shift count is negative}} \
  57               // cxx17-warning {{shift count is negative}} \
  58               // ref-warning {{shift count is negative}} \
  59               // ref-cxx17-warning {{shift count is negative}}
  60     c <<= 999999; // expected-warning {{shift count >= width of type}} \
  61                   // cxx17-warning {{shift count >= width of type}} \
  62                   // ref-warning {{shift count >= width of type}} \
  63                   // ref-cxx17-warning {{shift count >= width of type}}
  64     c >>= 999999; // expected-warning {{shift count >= width of type}} \
  65                   // cxx17-warning {{shift count >= width of type}} \
  66                   // ref-warning {{shift count >= width of type}} \
  67                   // ref-cxx17-warning {{shift count >= width of type}}
  68     c <<= __CHAR_BIT__; // expected-warning {{shift count >= width of type}} \
  69                         // cxx17-warning {{shift count >= width of type}} \
  70                         // ref-warning {{shift count >= width of type}} \
  71                         // ref-cxx17-warning {{shift count >= width of type}}
  72     c >>= __CHAR_BIT__; // expected-warning {{shift count >= width of type}} \
  73                         // cxx17-warning {{shift count >= width of type}} \
  74                         // ref-warning {{shift count >= width of type}} \
  75                         // ref-cxx17-warning {{shift count >= width of type}}
  76     c <<= __CHAR_BIT__+1; // expected-warning {{shift count >= width of type}} \
  77                           // cxx17-warning {{shift count >= width of type}} \
  78                           // ref-warning {{shift count >= width of type}} \
  79                           // ref-cxx17-warning {{shift count >= width of type}}
  80     c >>= __CHAR_BIT__+1; // expected-warning {{shift count >= width of type}} \
  81                           // cxx17-warning {{shift count >= width of type}} \
  82                           // ref-warning {{shift count >= width of type}} \
  83                           // ref-cxx17-warning {{shift count >= width of type}}
  84     (void)((long)c << __CHAR_BIT__);
  85
  86     int i; // cxx17-warning {{uninitialized variable}} \
  87            // ref-cxx17-warning {{uninitialized variable}}
  88     i = 1 << (__INT_WIDTH__ - 2);
  89     i = 2 << (__INT_WIDTH__ - 1); // cxx17-warning {{bits to represent, but 'int' only has}} \
  90                                   // ref-cxx17-warning {{bits to represent, but 'int' only has}}
  91     i = 1 << (__INT_WIDTH__ - 1); // cxx17-warning-not {{sets the sign bit of the shift expression}}
  92     i = -1 << (__INT_WIDTH__ - 1); // cxx17-warning {{shifting a negative signed value is undefined}} \
  93                                    // ref-cxx17-warning {{shifting a negative signed value is undefined}}
  94     i = -1 << 0; // cxx17-warning {{shifting a negative signed value is undefined}} \
  95                  // ref-cxx17-warning {{shifting a negative signed value is undefined}}
  96     i = 0 << (__INT_WIDTH__ - 1);
  97     i = (char)1 << (__INT_WIDTH__ - 2);
  98
  99     unsigned u; // cxx17-warning {{uninitialized variable}} \
 100                 // ref-cxx17-warning {{uninitialized variable}}
 101     u = 1U << (__INT_WIDTH__ - 1);
 102     u = 5U << (__INT_WIDTH__ - 1);
 103
 104     long long int lli; // cxx17-warning {{uninitialized variable}} \
 105                        // ref-cxx17-warning {{uninitialized variable}}
 106     lli = INT_MIN << 2; // cxx17-warning {{shifting a negative signed value is undefined}} \
 107                         // ref-cxx17-warning {{shifting a negative signed value is undefined}}
 108     lli = 1LL << (sizeof(long long) * __CHAR_BIT__ - 2);
 109   }
 110
 111   static_assert(1 << 4 == 16, "");
 112   constexpr unsigned m = 2 >> 1;
 113   static_assert(m == 1, "");
 114   constexpr unsigned char c = 0 << 8;
 115   static_assert(c == 0, "");
 116   static_assert(true << 1, "");
 117   static_assert(1 << (__INT_WIDTH__ +1) == 0, "");  // expected-error {{not an integral constant expression}} \
 118                                                     // expected-note {{>= width of type 'int'}} \
 119                                                     // cxx17-error {{not an integral constant expression}} \
 120                                                     // cxx17-note {{>= width of type 'int'}} \
 121                                                     // ref-error {{not an integral constant expression}} \
 122                                                     // ref-note {{>= width of type 'int'}} \
 123                                                     // ref-cxx17-error {{not an integral constant expression}} \
 124                                                     // ref-cxx17-note {{>= width of type 'int'}}
 125
 126   constexpr int i1 = 1 << -1; // expected-error {{must be initialized by a constant expression}} \
 127                               // expected-note {{negative shift count -1}} \
 128                               // cxx17-error {{must be initialized by a constant expression}} \
 129                               // cxx17-note {{negative shift count -1}} \
 130                               // ref-error {{must be initialized by a constant expression}} \
 131                               // ref-note {{negative shift count -1}} \
 132                               // ref-cxx17-error {{must be initialized by a constant expression}} \
 133                               // ref-cxx17-note {{negative shift count -1}}
 134
 135   constexpr int i2 = 1 << (__INT_WIDTH__ + 1); // expected-error {{must be initialized by a constant expression}} \
 136                                                // expected-note {{>= width of type}} \
 137                                                // cxx17-error {{must be initialized by a constant expression}} \
 138                                                // cxx17-note {{>= width of type}} \
 139                                                // ref-error {{must be initialized by a constant expression}} \
 140                                                // ref-note {{>= width of type}} \
 141                                                // ref-cxx17-error {{must be initialized by a constant expression}} \
 142                                                // ref-cxx17-note {{>= width of type}}
 143
 144   constexpr char c2 = 1;
 145   constexpr int i3 = c2 << (__CHAR_BIT__ + 1); // Not ill-formed
 146
 147   /// The purpose of these few lines is to test that we can shift more bits
 148   /// than an unsigned *of the host* has. There was a bug where we casted
 149   /// to host-unsigned. However, we cannot query what a host-unsigned even is
 150   /// here, so only test this on platforms where `sizeof(long long) > sizeof(unsigned)`.
 151   constexpr long long int L = 1;
 152   constexpr signed int R = (sizeof(unsigned) * 8) + 1;
 153   constexpr decltype(L) M  = (R > 32 && R < 64) ?  L << R : 0;
 154   constexpr decltype(L) M2 = (R > 32 && R < 64) ?  L >> R : 0;
 155
 156
 157   constexpr int signedShift() { // cxx17-error {{never produces a constant expression}} \
 158                                 // ref-cxx17-error {{never produces a constant expression}}
 159     return 1024 << 31; // cxx17-warning {{signed shift result}} \
 160                        // ref-cxx17-warning {{signed shift result}} \
 161                        // cxx17-note {{signed left shift discards bits}} \
 162                        // ref-cxx17-note {{signed left shift discards bits}}
 163   }
 164
 165   constexpr int negativeShift() { // cxx17-error {{never produces a constant expression}} \
 166                                   // ref-cxx17-error {{never produces a constant expression}}
 167     return -1 << 2; // cxx17-warning {{shifting a negative signed value is undefined}} \
 168                     // ref-cxx17-warning {{shifting a negative signed value is undefined}} \
 169                     // cxx17-note {{left shift of negative value -1}} \
 170                     // ref-cxx17-note {{left shift of negative value -1}}
 171   }
 172
 173   constexpr int foo(int a) {
 174     return -a << 2; // cxx17-note {{left shift of negative value -10}} \
 175                     // ref-cxx17-note {{left shift of negative value -10}} \
 176                     // cxx17-note {{left shift of negative value -2}} \
 177                     // ref-cxx17-note {{left shift of negative value -2}}
 178   }
 179   static_assert(foo(10)); // cxx17-error {{not an integral constant expression}} \
 180                           // cxx17-note {{in call to 'foo(10)'}} \
 181                           // ref-cxx17-error {{not an integral constant expression}} \
 182                           // ref-cxx17-note {{in call to 'foo(10)'}}
 183
 184   constexpr int a = -2;
 185   static_assert(foo(a));
 186   static_assert(foo(-a)); // cxx17-error {{not an integral constant expression}} \
 187                           // cxx17-note {{in call to 'foo(2)'}} \
 188                           // ref-cxx17-error {{not an integral constant expression}} \
 189                           // ref-cxx17-note {{in call to 'foo(2)'}}
 190 };