clang/test/SemaCXX/rounding-math.cpp

   1 // RUN: %clang_cc1 -triple x86_64-linux -verify=norounding -Wno-unknown-pragmas %s
   2 // RUN: %clang_cc1 -triple x86_64-linux -verify=rounding %s -frounding-math -Wno-unknown-pragmas
   3 // RUN: %clang_cc1 -triple x86_64-linux -verify=rounding %s -frounding-math -fexperimental-new-constant-interpreter -Wno-unknown-pragmas
   4 // rounding-no-diagnostics
   5
   6 #define fold(x) (__builtin_constant_p(x) ? (x) : (x))
   7
   8 constexpr double a = 1.0 / 3.0;
   9
  10 constexpr int f(int n) { return int(n * (1.0 / 3.0)); }
  11
  12 using T = int[f(3)];
  13 using T = int[1];
  14
  15 enum Enum { enum_a = f(3) };
  16
  17 struct Bitfield {
  18   unsigned int n : 1;
  19   unsigned int m : f(3);
  20 };
  21
  22 void f(Bitfield &b) {
  23   b.n = int(6 * (1.0 / 3.0)); // norounding-warning {{changes value from 2 to 0}}
  24 }
  25
  26 const int k = 3 * (1.0 / 3.0);
  27 static_assert(k == 1, "");
  28
  29 void g() {
  30   // FIXME: Constant-evaluating this initializer is surprising, and violates
  31   // the recommended practice in C++ [expr.const]p12:
  32   //
  33   //   Implementations should provide consistent results of floating-point
  34   //   evaluations, irrespective of whether the evaluation is performed during
  35   //   translation or during program execution.
  36   const int k = 3 * (1.0 / 3.0);
  37   static_assert(k == 1, "");
  38 }
  39
  40 int *h() {
  41   return new int[int(-3 * (1.0 / 3.0))]; // norounding-error {{too large}}
  42 }
  43
  44
  45 // nextUp(1.F) == 0x1.000002p0F
  46 static_assert(1.0F + 0x0.000001p0F == 0x1.0p0F, "");
  47
  48 char Arr01[1 + (1.0F + 0x0.000001p0F > 1.0F)];
  49 static_assert(sizeof(Arr01) == 1, "");
  50
  51 struct S1 {
  52   int : (1.0F + 0x0.000001p0F > 1.0F);
  53   int f;
  54 };
  55 static_assert(sizeof(S1) == sizeof(int), "");
  56
  57 #pragma STDC FENV_ROUND FE_UPWARD
  58 static_assert(1.0F + 0x0.000001p0F == 0x1.000002p0F, "");
  59
  60 char Arr01u[1 + (1.0F + 0x0.000001p0F > 1.0F)];
  61 static_assert(sizeof(Arr01u) == 2, "");
  62
  63 struct S1u {
  64   int : (1.0F + 0x0.000001p0F > 1.0F);
  65   int f;
  66 };
  67 static_assert(sizeof(S1u) > sizeof(int), "");
  68
  69 #pragma STDC FENV_ROUND FE_DOWNWARD
  70 static_assert(1.0F + 0x0.000001p0F == 1.0F, "");
  71
  72 char Arr01d[1 + (1.0F + 0x0.000001p0F > 1.0F)];
  73 static_assert(sizeof(Arr01d) == 1, "");
  74
  75 struct S1d {
  76   int : (1.0F + 0x0.000001p0F > 1.0F);
  77   int f;
  78 };
  79 static_assert(sizeof(S1d) == sizeof(int), "");
  80
  81 constexpr float incr_down(float k) {
  82   float x = k;
  83   ++x;
  84   return x;
  85 }
  86
  87 // 0x1.0p23 = 8388608.0, inc(8388608.0) = 8388609.0
  88 static_assert(incr_down(0x1.0p23F) == 0x1.000002p23F, "");
  89 // 0x1.0p24 = 16777216.0, inc(16777216.0) = 16777217.0 -> round down -> 16777216.0
  90 static_assert(incr_down(0x1.0p24F) == 0x1.0p24F, "");
  91
  92 #pragma STDC FENV_ROUND FE_UPWARD
  93 constexpr float incr_up(float k) {
  94   float x = k;
  95   ++x;
  96   return x;
  97 }
  98 static_assert(incr_up(0x1.0p23F) == 0x1.000002p23F, "");
  99 // 0x1.0p24 = 16777216.0, inc(16777216.0) = 16777217.0 -> round up -> 16777218.0
 100 static_assert(incr_up(0x1.0p24F) == 0x1.000002p24F, "");