libc/test/src/math/exp2_test.cpp

   1 //===-- Unittests for 2^x -------------------------------------------------===//
   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/exp2.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 <errno.h>
  18 #include <stdint.h>
  19
  20 using LlvmLibcExp2Test = LIBC_NAMESPACE::testing::FPTest<double>;
  21
  22 namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
  23 using LIBC_NAMESPACE::testing::tlog;
  24
  25 TEST_F(LlvmLibcExp2Test, SpecialNumbers) {
  26   EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::exp2(aNaN));
  27   EXPECT_FP_EQ(inf, LIBC_NAMESPACE::exp2(inf));
  28   EXPECT_FP_EQ_ALL_ROUNDING(zero, LIBC_NAMESPACE::exp2(neg_inf));
  29   EXPECT_FP_EQ_WITH_EXCEPTION(zero, LIBC_NAMESPACE::exp2(-0x1.0p20),
  30                               FE_UNDERFLOW);
  31   EXPECT_FP_EQ_WITH_EXCEPTION(inf, LIBC_NAMESPACE::exp2(0x1.0p20), FE_OVERFLOW);
  32   EXPECT_FP_EQ_ALL_ROUNDING(1.0, LIBC_NAMESPACE::exp2(0.0));
  33   EXPECT_FP_EQ_ALL_ROUNDING(1.0, LIBC_NAMESPACE::exp2(-0.0));
  34 }
  35
  36 TEST_F(LlvmLibcExp2Test, TrickyInputs) {
  37   constexpr int N = 16;
  38   constexpr uint64_t INPUTS[N] = {
  39       0x3FD79289C6E6A5C0,
  40       0x3FD05DE80A173EA0, // 0x1.05de80a173eap-2
  41       0xbf1eb7a4cb841fcc, // -0x1.eb7a4cb841fccp-14
  42       0xbf19a61fb925970d,
  43       0x3fda7b764e2cf47a, // 0x1.a7b764e2cf47ap-2
  44       0xc04757852a4b93aa, // -0x1.757852a4b93aap+5
  45       0x4044c19e5712e377, // x=0x1.4c19e5712e377p+5
  46       0xbf19a61fb925970d, // x=-0x1.9a61fb925970dp-14
  47       0xc039a74cdab36c28, // x=-0x1.9a74cdab36c28p+4
  48       0xc085b3e4e2e3bba9, // x=-0x1.5b3e4e2e3bba9p+9
  49       0xc086960d591aec34, // x=-0x1.6960d591aec34p+9
  50       0xc086232c09d58d91, // x=-0x1.6232c09d58d91p+9
  51       0xc0874910d52d3051, // x=-0x1.74910d52d3051p9
  52       0xc0867a172ceb0990, // x=-0x1.67a172ceb099p+9
  53       0xc08ff80000000000, // x=-0x1.ff8p+9
  54       0xbc971547652b82fe, // x=-0x1.71547652b82fep-54
  55   };
  56   for (int i = 0; i < N; ++i) {
  57     double x = double(FPBits(INPUTS[i]));
  58     EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp2, x,
  59                                    LIBC_NAMESPACE::exp2(x), 0.5);
  60   }
  61 }
  62
  63 TEST_F(LlvmLibcExp2Test, InDoubleRange) {
  64   constexpr uint64_t COUNT = 1'231;
  65   uint64_t START = LIBC_NAMESPACE::fputil::FPBits<double>(0.25).uintval();
  66   uint64_t STOP = LIBC_NAMESPACE::fputil::FPBits<double>(4.0).uintval();
  67   uint64_t STEP = (STOP - START) / COUNT;
  68
  69   auto test = [&](mpfr::RoundingMode rounding_mode) {
  70     mpfr::ForceRoundingMode __r(rounding_mode);
  71     if (!__r.success)
  72       return;
  73
  74     uint64_t fails = 0;
  75     uint64_t count = 0;
  76     uint64_t cc = 0;
  77     double mx, mr = 0.0;
  78     double tol = 0.5;
  79
  80     for (uint64_t i = 0, v = START; i <= COUNT; ++i, v += STEP) {
  81       double x = FPBits(v).get_val();
  82       if (isnan(x) || isinf(x) || x < 0.0)
  83         continue;
  84       libc_errno = 0;
  85       double result = LIBC_NAMESPACE::exp2(x);
  86       ++cc;
  87       if (isnan(result) || isinf(result))
  88         continue;
  89
  90       ++count;
  91
  92       if (!TEST_MPFR_MATCH_ROUNDING_SILENTLY(mpfr::Operation::Exp2, x, result,
  93                                              0.5, rounding_mode)) {
  94         ++fails;
  95         while (!TEST_MPFR_MATCH_ROUNDING_SILENTLY(mpfr::Operation::Exp2, x,
  96                                                   result, tol, rounding_mode)) {
  97           mx = x;
  98           mr = result;
  99
 100           if (tol > 1000.0)
 101             break;
 102
 103           tol *= 2.0;
 104         }
 105       }
 106     }
 107     tlog << " Exp2 failed: " << fails << "/" << count << "/" << cc
 108          << " tests.\n";
 109     tlog << "   Max ULPs is at most: " << static_cast<uint64_t>(tol) << ".\n";
 110     if (fails) {
 111       EXPECT_MPFR_MATCH(mpfr::Operation::Exp2, mx, mr, 0.5, rounding_mode);
 112     }
 113   };
 114
 115   tlog << " Test Rounding To Nearest...\n";
 116   test(mpfr::RoundingMode::Nearest);
 117
 118   tlog << " Test Rounding Downward...\n";
 119   test(mpfr::RoundingMode::Downward);
 120
 121   tlog << " Test Rounding Upward...\n";
 122   test(mpfr::RoundingMode::Upward);
 123
 124   tlog << " Test Rounding Toward Zero...\n";
 125   test(mpfr::RoundingMode::TowardZero);
 126 }