text: // RUN: %clang_builtins %s %librt -o %t && %run %t
  
  #define DOUBLE_PRECISION
  #include <fenv.h>
  #include <float.h>
  #include <limits.h>
  #include <math.h>
  #include <stdio.h>
  #include "fp_lib.h"
  
  int test__compiler_rt_scalbn(const char *mode, fp_t x, int y) {
    fp_t crt_value = __compiler_rt_scalbn(x, y);
    fp_t libm_value = scalbn(x, y);
    // Consider +/-0 unequal, but disregard the sign/payload of NaN.
    if (toRep(crt_value) != toRep(libm_value) &&
        !(crt_isnan(crt_value) && crt_isnan(libm_value))) {
      printf("error: [%s] in __compiler_rt_scalbn(%a [%llX], %d) = %a [%llX] "
             "!= %a [%llX]\n",
             mode, x, (unsigned long long)toRep(x), y,
             crt_value, (unsigned long long)toRep(crt_value),
             libm_value, (unsigned long long)toRep(libm_value));
      return 1;
    }
    return 0;
  }
  
  fp_t cases[] = {
    -NAN, NAN, -INFINITY, INFINITY, -0.0, 0.0, -1, 1, -2, 2,
    DBL_TRUE_MIN, DBL_TRUE_MIN*7, DBL_MIN, DBL_MAX,
    -1.001, 1.001, -1.002, 1.002, 1.e-6, -1.e-6,
    0x1.0p-1021,
    0x1.0p-1022,
    0x1.0p-1023, // subnormal
    0x1.0p-1024, // subnormal
  };
  
  int iterate_cases(const char *mode) {
    const unsigned N = sizeof(cases) / sizeof(cases[0]);
    unsigned i;
    for (i = 0; i < N; ++i) {
      int j;
      for (j = -5; j <= 5; ++j) {
        if (test__compiler_rt_scalbn(mode, cases[i], j)) return 1;
      }
      if (test__compiler_rt_scalbn(mode, cases[i], -10000)) return 1;
      if (test__compiler_rt_scalbn(mode, cases[i], 10000)) return 1;
      if (test__compiler_rt_scalbn(mode, cases[i], INT_MIN)) return 1;
      if (test__compiler_rt_scalbn(mode, cases[i], INT_MAX)) return 1;
    }
    return 0;
  }
  
  int main() {
    if (iterate_cases("default")) return 1;
  
    // Rounding mode tests on supported architectures. __compiler_rt_scalbn
    // should have the same rounding behavior as double-precision multiplication.
  #if (defined(__arm__) || defined(__aarch64__)) && defined(__ARM_FP) || \
      defined(__i386__) || defined(__x86_64__)
  // Skip these tests for MSVC because its scalbn function always behaves as if
  // the default rounding mode is set (FE_TONEAREST).
  #ifndef _MSC_VER
    fesetround(FE_UPWARD);
    if (iterate_cases("FE_UPWARD")) return 1;
  
    fesetround(FE_DOWNWARD);
    if (iterate_cases("FE_DOWNWARD")) return 1;
  
    fesetround(FE_TOWARDZERO);
    if (iterate_cases("FE_TOWARDZERO")) return 1;
  #endif
  
    fesetround(FE_TONEAREST);
    if (iterate_cases("FE_TONEAREST")) return 1;
  #endif
  
    return 0;
  }
  