1 //===-- Unittests for exp2f -----------------------------------------------===//
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 "include/errno.h"
10 #include "include/math.h"
11 #include "src/errno/llvmlibc_errno.h"
12 #include "src/math/exp2f.h"
13 #include "utils/FPUtil/BitPatterns.h"
14 #include "utils/FPUtil/FloatOperations.h"
15 #include "utils/FPUtil/FloatProperties.h"
16 #include "utils/MPFRWrapper/MPFRUtils.h"
17 #include "utils/UnitTest/Test.h"
18 
19 #include <stdint.h>
20 
21 using __llvm_libc::fputil::isNegativeQuietNaN;
22 using __llvm_libc::fputil::isQuietNaN;
23 using __llvm_libc::fputil::valueAsBits;
24 using __llvm_libc::fputil::valueFromBits;
25 
26 using BitPatterns = __llvm_libc::fputil::BitPatterns<float>;
27 
28 namespace mpfr = __llvm_libc::testing::mpfr;
29 
30 // 12 additional bits of precision over the base precision of a |float|
31 // value.
32 static constexpr mpfr::Tolerance tolerance{mpfr::Tolerance::floatPrecision, 12,
33                                            0xFFF};
34 
35 TEST(exp2fTest, SpecialNumbers) {
36   llvmlibc_errno = 0;
37 
38   EXPECT_TRUE(
39       isQuietNaN(__llvm_libc::exp2f(valueFromBits(BitPatterns::aQuietNaN))));
40   EXPECT_EQ(llvmlibc_errno, 0);
41 
42   EXPECT_TRUE(isNegativeQuietNaN(
43       __llvm_libc::exp2f(valueFromBits(BitPatterns::aNegativeQuietNaN))));
44   EXPECT_EQ(llvmlibc_errno, 0);
45 
46   EXPECT_TRUE(isQuietNaN(
47       __llvm_libc::exp2f(valueFromBits(BitPatterns::aSignallingNaN))));
48   EXPECT_EQ(llvmlibc_errno, 0);
49 
50   EXPECT_TRUE(isNegativeQuietNaN(
51       __llvm_libc::exp2f(valueFromBits(BitPatterns::aNegativeSignallingNaN))));
52   EXPECT_EQ(llvmlibc_errno, 0);
53 
54   EXPECT_EQ(BitPatterns::inf,
55             valueAsBits(__llvm_libc::exp2f(valueFromBits(BitPatterns::inf))));
56   EXPECT_EQ(llvmlibc_errno, 0);
57 
58   EXPECT_EQ(BitPatterns::zero, valueAsBits(__llvm_libc::exp2f(
59                                    valueFromBits(BitPatterns::negInf))));
60   EXPECT_EQ(llvmlibc_errno, 0);
61 
62   EXPECT_EQ(BitPatterns::one,
63             valueAsBits(__llvm_libc::exp2f(valueFromBits(BitPatterns::zero))));
64   EXPECT_EQ(llvmlibc_errno, 0);
65 
66   EXPECT_EQ(BitPatterns::one, valueAsBits(__llvm_libc::exp2f(
67                                   valueFromBits(BitPatterns::negZero))));
68   EXPECT_EQ(llvmlibc_errno, 0);
69 }
70 
71 TEST(ExpfTest, Overflow) {
72   llvmlibc_errno = 0;
73   EXPECT_EQ(BitPatterns::inf,
74             valueAsBits(__llvm_libc::exp2f(valueFromBits(0x7f7fffffU))));
75   EXPECT_EQ(llvmlibc_errno, ERANGE);
76 
77   llvmlibc_errno = 0;
78   EXPECT_EQ(BitPatterns::inf,
79             valueAsBits(__llvm_libc::exp2f(valueFromBits(0x43000000U))));
80   EXPECT_EQ(llvmlibc_errno, ERANGE);
81 
82   llvmlibc_errno = 0;
83   EXPECT_EQ(BitPatterns::inf,
84             valueAsBits(__llvm_libc::exp2f(valueFromBits(0x43000001U))));
85   EXPECT_EQ(llvmlibc_errno, ERANGE);
86 }
87 
88 // Test with inputs which are the borders of underflow/overflow but still
89 // produce valid results without setting errno.
90 TEST(ExpfTest, Borderline) {
91   float x;
92 
93   llvmlibc_errno = 0;
94   x = valueFromBits(0x42fa0001U);
95   EXPECT_MPFR_MATCH(mpfr::OP_Exp2, x, __llvm_libc::exp2f(x), tolerance);
96   EXPECT_EQ(llvmlibc_errno, 0);
97 
98   x = valueFromBits(0x42ffffffU);
99   EXPECT_MPFR_MATCH(mpfr::OP_Exp2, x, __llvm_libc::exp2f(x), tolerance);
100   EXPECT_EQ(llvmlibc_errno, 0);
101 
102   x = valueFromBits(0xc2fa0001U);
103   EXPECT_MPFR_MATCH(mpfr::OP_Exp2, x, __llvm_libc::exp2f(x), tolerance);
104   EXPECT_EQ(llvmlibc_errno, 0);
105 
106   x = valueFromBits(0xc2fc0000U);
107   EXPECT_MPFR_MATCH(mpfr::OP_Exp2, x, __llvm_libc::exp2f(x), tolerance);
108   EXPECT_EQ(llvmlibc_errno, 0);
109 
110   x = valueFromBits(0xc2fc0001U);
111   EXPECT_MPFR_MATCH(mpfr::OP_Exp2, x, __llvm_libc::exp2f(x), tolerance);
112   EXPECT_EQ(llvmlibc_errno, 0);
113 
114   x = valueFromBits(0xc3150000U);
115   EXPECT_MPFR_MATCH(mpfr::OP_Exp2, x, __llvm_libc::exp2f(x), tolerance);
116   EXPECT_EQ(llvmlibc_errno, 0);
117 }
118 
119 TEST(ExpfTest, Underflow) {
120   llvmlibc_errno = 0;
121   EXPECT_EQ(BitPatterns::zero,
122             valueAsBits(__llvm_libc::exp2f(valueFromBits(0xff7fffffU))));
123   EXPECT_EQ(llvmlibc_errno, ERANGE);
124 
125   llvmlibc_errno = 0;
126   float x = valueFromBits(0xc3158000U);
127   EXPECT_MPFR_MATCH(mpfr::OP_Exp2, x, __llvm_libc::exp2f(x), tolerance);
128   EXPECT_EQ(llvmlibc_errno, ERANGE);
129 
130   llvmlibc_errno = 0;
131   x = valueFromBits(0xc3165432U);
132   EXPECT_MPFR_MATCH(mpfr::OP_Exp2, x, __llvm_libc::exp2f(x), tolerance);
133   EXPECT_EQ(llvmlibc_errno, ERANGE);
134 }
135 
136 TEST(exp2fTest, InFloatRange) {
137   constexpr uint32_t count = 1000000;
138   constexpr uint32_t step = UINT32_MAX / count;
139   for (uint32_t i = 0, v = 0; i <= count; ++i, v += step) {
140     float x = valueFromBits(v);
141     if (isnan(x) || isinf(x))
142       continue;
143     llvmlibc_errno = 0;
144     float result = __llvm_libc::exp2f(x);
145 
146     // If the computation resulted in an error or did not produce valid result
147     // in the single-precision floating point range, then ignore comparing with
148     // MPFR result as MPFR can still produce valid results because of its
149     // wider precision.
150     if (isnan(result) || isinf(result) || llvmlibc_errno != 0)
151       continue;
152     ASSERT_MPFR_MATCH(mpfr::OP_Exp2, x, __llvm_libc::exp2f(x), tolerance);
153   }
154 }
155