libc/test/src/math/expf_test.cpp

   1 //===-- Unittests for expf ------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/__support/FPUtil/FPBits.h"
  10 #include "src/errno/libc_errno.h"
  11 #include "src/math/expf.h"
  12 #include "test/UnitTest/FPMatcher.h"
  13 #include "test/UnitTest/Test.h"
  14 #include "utils/MPFRWrapper/MPFRUtils.h"
  15 #include <math.h>
  16
  17 #include <stdint.h>
  18
  19 using LlvmLibcExpfTest = LIBC_NAMESPACE::testing::FPTest<float>;
  20
  21 namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
  22
  23 TEST_F(LlvmLibcExpfTest, SpecialNumbers) {
  24   libc_errno = 0;
  25
  26   EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::expf(aNaN));
  27   EXPECT_MATH_ERRNO(0);
  28
  29   EXPECT_FP_EQ(inf, LIBC_NAMESPACE::expf(inf));
  30   EXPECT_MATH_ERRNO(0);
  31
  32   EXPECT_FP_EQ(0.0f, LIBC_NAMESPACE::expf(neg_inf));
  33   EXPECT_MATH_ERRNO(0);
  34
  35   EXPECT_FP_EQ(1.0f, LIBC_NAMESPACE::expf(0.0f));
  36   EXPECT_MATH_ERRNO(0);
  37
  38   EXPECT_FP_EQ(1.0f, LIBC_NAMESPACE::expf(-0.0f));
  39   EXPECT_MATH_ERRNO(0);
  40 }
  41
  42 TEST_F(LlvmLibcExpfTest, Overflow) {
  43   libc_errno = 0;
  44   EXPECT_FP_EQ_WITH_EXCEPTION(
  45       inf, LIBC_NAMESPACE::expf(float(FPBits(0x7f7fffffU))), FE_OVERFLOW);
  46   EXPECT_MATH_ERRNO(ERANGE);
  47
  48   EXPECT_FP_EQ_WITH_EXCEPTION(
  49       inf, LIBC_NAMESPACE::expf(float(FPBits(0x42cffff8U))), FE_OVERFLOW);
  50   EXPECT_MATH_ERRNO(ERANGE);
  51
  52   EXPECT_FP_EQ_WITH_EXCEPTION(
  53       inf, LIBC_NAMESPACE::expf(float(FPBits(0x42d00008U))), FE_OVERFLOW);
  54   EXPECT_MATH_ERRNO(ERANGE);
  55 }
  56
  57 TEST_F(LlvmLibcExpfTest, Underflow) {
  58   libc_errno = 0;
  59   EXPECT_FP_EQ_WITH_EXCEPTION(
  60       0.0f, LIBC_NAMESPACE::expf(float(FPBits(0xff7fffffU))), FE_UNDERFLOW);
  61   EXPECT_MATH_ERRNO(ERANGE);
  62
  63   float x = float(FPBits(0xc2cffff8U));
  64   EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x,
  65                                  LIBC_NAMESPACE::expf(x), 0.5);
  66   EXPECT_MATH_ERRNO(ERANGE);
  67
  68   x = float(FPBits(0xc2d00008U));
  69   EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x,
  70                                  LIBC_NAMESPACE::expf(x), 0.5);
  71   EXPECT_MATH_ERRNO(ERANGE);
  72 }
  73
  74 // Test with inputs which are the borders of underflow/overflow but still
  75 // produce valid results without setting errno.
  76 TEST_F(LlvmLibcExpfTest, Borderline) {
  77   float x;
  78
  79   libc_errno = 0;
  80   x = float(FPBits(0x42affff8U));
  81   ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x,
  82                                  LIBC_NAMESPACE::expf(x), 0.5);
  83   EXPECT_MATH_ERRNO(0);
  84
  85   x = float(FPBits(0x42b00008U));
  86   ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x,
  87                                  LIBC_NAMESPACE::expf(x), 0.5);
  88   EXPECT_MATH_ERRNO(0);
  89
  90   x = float(FPBits(0xc2affff8U));
  91   ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x,
  92                                  LIBC_NAMESPACE::expf(x), 0.5);
  93   EXPECT_MATH_ERRNO(0);
  94
  95   x = float(FPBits(0xc2b00008U));
  96   ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x,
  97                                  LIBC_NAMESPACE::expf(x), 0.5);
  98   EXPECT_MATH_ERRNO(0);
  99
 100   x = float(FPBits(0xc236bd8cU));
 101   EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x,
 102                                  LIBC_NAMESPACE::expf(x), 0.5);
 103   EXPECT_MATH_ERRNO(0);
 104 }
 105
 106 TEST_F(LlvmLibcExpfTest, InFloatRange) {
 107   constexpr uint32_t COUNT = 100'000;
 108   constexpr uint32_t STEP = UINT32_MAX / COUNT;
 109   for (uint32_t i = 0, v = 0; i <= COUNT; ++i, v += STEP) {
 110     float x = float(FPBits(v));
 111     if (isnan(x) || isinf(x))
 112       continue;
 113     libc_errno = 0;
 114     float result = LIBC_NAMESPACE::expf(x);
 115
 116     // If the computation resulted in an error or did not produce valid result
 117     // in the single-precision floating point range, then ignore comparing with
 118     // MPFR result as MPFR can still produce valid results because of its
 119     // wider precision.
 120     if (isnan(result) || isinf(result) || libc_errno != 0)
 121       continue;
 122     EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x,
 123                                    LIBC_NAMESPACE::expf(x), 0.5);
 124   }
 125 }