libc/test/src/math/log2_test.cpp

   1 //===-- Unittests for log2 ------------------------------------------------===//
   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/log2.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 namespace mpfr = __llvm_libc::testing::mpfr;
  21 using __llvm_libc::testing::tlog;
  22
  23 DECLARE_SPECIAL_CONSTANTS(double)
  24
  25 TEST(LlvmLibcLog2Test, SpecialNumbers) {
  26   EXPECT_FP_EQ(aNaN, __llvm_libc::log2(aNaN));
  27   EXPECT_FP_EQ(inf, __llvm_libc::log2(inf));
  28   EXPECT_FP_IS_NAN_WITH_EXCEPTION(__llvm_libc::log2(neg_inf), FE_INVALID);
  29   EXPECT_FP_EQ_WITH_EXCEPTION(neg_inf, __llvm_libc::log2(0.0), FE_DIVBYZERO);
  30   EXPECT_FP_EQ_WITH_EXCEPTION(neg_inf, __llvm_libc::log2(-0.0), FE_DIVBYZERO);
  31   EXPECT_FP_IS_NAN_WITH_EXCEPTION(__llvm_libc::log2(-1.0), FE_INVALID);
  32   EXPECT_FP_EQ_ALL_ROUNDING(zero, __llvm_libc::log2(1.0));
  33 }
  34
  35 TEST(LlvmLibcLog2Test, TrickyInputs) {
  36   constexpr int N = 30;
  37   constexpr uint64_t INPUTS[N] = {
  38       0x3ff0000000000000, // x = 1.0
  39       0x4024000000000000, // x = 10.0
  40       0x4059000000000000, // x = 10^2
  41       0x408f400000000000, // x = 10^3
  42       0x40c3880000000000, // x = 10^4
  43       0x40f86a0000000000, // x = 10^5
  44       0x412e848000000000, // x = 10^6
  45       0x416312d000000000, // x = 10^7
  46       0x4197d78400000000, // x = 10^8
  47       0x41cdcd6500000000, // x = 10^9
  48       0x4202a05f20000000, // x = 10^10
  49       0x42374876e8000000, // x = 10^11
  50       0x426d1a94a2000000, // x = 10^12
  51       0x42a2309ce5400000, // x = 10^13
  52       0x42d6bcc41e900000, // x = 10^14
  53       0x430c6bf526340000, // x = 10^15
  54       0x4341c37937e08000, // x = 10^16
  55       0x4376345785d8a000, // x = 10^17
  56       0x43abc16d674ec800, // x = 10^18
  57       0x43e158e460913d00, // x = 10^19
  58       0x4415af1d78b58c40, // x = 10^20
  59       0x444b1ae4d6e2ef50, // x = 10^21
  60       0x4480f0cf064dd592, // x = 10^22
  61       0x3fefffffffef06ad, 0x3fefde0f22c7d0eb, 0x225e7812faadb32f,
  62       0x3fee1076964c2903, 0x3fdfe93fff7fceb0, 0x3ff012631ad8df10,
  63       0x3fefbfdaa448ed98,
  64   };
  65   for (int i = 0; i < N; ++i) {
  66     double x = double(FPBits(INPUTS[i]));
  67     EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Log2, x,
  68                                    __llvm_libc::log2(x), 0.5);
  69   }
  70 }
  71
  72 TEST(LlvmLibcLog2Test, AllExponents) {
  73   double x = 0x1.0p-1074;
  74   for (int i = -1074; i < 1024; ++i, x *= 2.0) {
  75     ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Log2, x,
  76                                    __llvm_libc::log2(x), 0.5);
  77   }
  78 }
  79
  80 TEST(LlvmLibcLog2Test, InDoubleRange) {
  81   constexpr uint64_t COUNT = 234561;
  82   constexpr uint64_t START = 0x3FD0'0000'0000'0000ULL; // 0.25
  83   constexpr uint64_t STOP = 0x4010'0000'0000'0000ULL;  // 4.0
  84   // constexpr uint64_t START = 0x3FF0'0000'0000'0000ULL;  // 1.0
  85   // constexpr uint64_t STOP = 0x4000'0000'0000'0000ULL;   // 2.0
  86   constexpr uint64_t STEP = (STOP - START) / COUNT;
  87
  88   auto test = [&](mpfr::RoundingMode rounding_mode) {
  89     mpfr::ForceRoundingMode __r(rounding_mode);
  90     uint64_t fails = 0;
  91     uint64_t count = 0;
  92     uint64_t cc = 0;
  93     double mx, mr = 0.0;
  94     double tol = 0.5;
  95
  96     for (uint64_t i = 0, v = START; i <= COUNT; ++i, v += STEP) {
  97       double x = FPBits(v).get_val();
  98       if (isnan(x) || isinf(x) || x < 0.0)
  99         continue;
 100       libc_errno = 0;
 101       double result = __llvm_libc::log2(x);
 102       ++cc;
 103       if (isnan(result) || isinf(result))
 104         continue;
 105
 106       ++count;
 107       // ASSERT_MPFR_MATCH(mpfr::Operation::Log2, x, result, 0.5);
 108       if (!EXPECT_MPFR_MATCH_ROUNDING_SILENTLY(mpfr::Operation::Log2, x, result,
 109                                                0.5, rounding_mode)) {
 110         ++fails;
 111         while (!EXPECT_MPFR_MATCH_ROUNDING_SILENTLY(
 112             mpfr::Operation::Log2, x, result, tol, rounding_mode)) {
 113           mx = x;
 114           mr = result;
 115           tol *= 2.0;
 116         }
 117       }
 118     }
 119     tlog << " Log2 failed: " << fails << "/" << count << "/" << cc
 120          << " tests.\n";
 121     tlog << "   Max ULPs is at most: " << static_cast<uint64_t>(tol) << ".\n";
 122     if (fails) {
 123       EXPECT_MPFR_MATCH(mpfr::Operation::Log2, mx, mr, 0.5, rounding_mode);
 124     }
 125   };
 126
 127   tlog << " Test Rounding To Nearest...\n";
 128   test(mpfr::RoundingMode::Nearest);
 129
 130   tlog << " Test Rounding Downward...\n";
 131   test(mpfr::RoundingMode::Downward);
 132
 133   tlog << " Test Rounding Upward...\n";
 134   test(mpfr::RoundingMode::Upward);
 135
 136   tlog << " Test Rounding Toward Zero...\n";
 137   test(mpfr::RoundingMode::TowardZero);
 138 }