1 // Copyright 2015, VIXL authors
2 // All rights reserved.
3 //
4 // Redistribution and use in source and binary forms, with or without
5 // modification, are permitted provided that the following conditions are met:
6 //
7 // * Redistributions of source code must retain the above copyright notice,
8 // this list of conditions and the following disclaimer.
9 // * Redistributions in binary form must reproduce the above copyright notice,
10 // this list of conditions and the following disclaimer in the documentation
11 // and/or other materials provided with the distribution.
12 // * Neither the name of ARM Limited nor the names of its contributors may be
13 // used to endorse or promote products derived from this software without
14 // specific prior written permission.
15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
17 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
20 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
23 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26
27
28 #ifndef VIXL_COMPILER_INTRINSICS_H
29 #define VIXL_COMPILER_INTRINSICS_H
30
31 #include "globals-vixl.h"
32
33 namespace vixl {
34
35 // Helper to check whether the version of GCC used is greater than the specified
36 // requirement.
37 #define MAJOR 1000000
38 #define MINOR 1000
39 #if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
40 #define GCC_VERSION_OR_NEWER(major, minor, patchlevel) \
41 ((__GNUC__ * (MAJOR) + __GNUC_MINOR__ * (MINOR) + __GNUC_PATCHLEVEL__) >= \
42 ((major) * (MAJOR) + ((minor)) * (MINOR) + (patchlevel)))
43 #elif defined(__GNUC__) && defined(__GNUC_MINOR__)
44 #define GCC_VERSION_OR_NEWER(major, minor, patchlevel) \
45 ((__GNUC__ * (MAJOR) + __GNUC_MINOR__ * (MINOR)) >= \
46 ((major) * (MAJOR) + ((minor)) * (MINOR) + (patchlevel)))
47 #else
48 #define GCC_VERSION_OR_NEWER(major, minor, patchlevel) 0
49 #endif
50
51
52 #if defined(__clang__) && !defined(VIXL_NO_COMPILER_BUILTINS)
53
54 // clang-format off
55 #define COMPILER_HAS_BUILTIN_CLRSB (__has_builtin(__builtin_clrsb))
56 #define COMPILER_HAS_BUILTIN_CLZ (__has_builtin(__builtin_clz))
57 #define COMPILER_HAS_BUILTIN_CTZ (__has_builtin(__builtin_ctz))
58 #define COMPILER_HAS_BUILTIN_FFS (__has_builtin(__builtin_ffs))
59 #define COMPILER_HAS_BUILTIN_POPCOUNT (__has_builtin(__builtin_popcount))
60 // clang-format on
61
62 #elif defined(__GNUC__) && !defined(VIXL_NO_COMPILER_BUILTINS)
63 // The documentation for these builtins is available at:
64 // https://gcc.gnu.org/onlinedocs/gcc-$MAJOR.$MINOR.$PATCHLEVEL/gcc//Other-Builtins.html
65
66 // clang-format off
67 # define COMPILER_HAS_BUILTIN_CLRSB (GCC_VERSION_OR_NEWER(4, 7, 0))
68 # define COMPILER_HAS_BUILTIN_CLZ (GCC_VERSION_OR_NEWER(3, 4, 0))
69 # define COMPILER_HAS_BUILTIN_CTZ (GCC_VERSION_OR_NEWER(3, 4, 0))
70 # define COMPILER_HAS_BUILTIN_FFS (GCC_VERSION_OR_NEWER(3, 4, 0))
71 # define COMPILER_HAS_BUILTIN_POPCOUNT (GCC_VERSION_OR_NEWER(3, 4, 0))
72 // clang-format on
73
74 #else
75 // One can define VIXL_NO_COMPILER_BUILTINS to force using the manually
76 // implemented C++ methods.
77
78 // clang-format off
79 #define COMPILER_HAS_BUILTIN_BSWAP false
80 #define COMPILER_HAS_BUILTIN_CLRSB false
81 #define COMPILER_HAS_BUILTIN_CLZ false
82 #define COMPILER_HAS_BUILTIN_CTZ false
83 #define COMPILER_HAS_BUILTIN_FFS false
84 #define COMPILER_HAS_BUILTIN_POPCOUNT false
85 // clang-format on
86
87 #endif
88
89
90 template <typename V>
IsPowerOf2(V value)91 inline bool IsPowerOf2(V value) {
92 return (value != 0) && ((value & (value - 1)) == 0);
93 }
94
95
96 // Declaration of fallback functions.
97 int CountLeadingSignBitsFallBack(int64_t value, int width);
98 int CountLeadingZerosFallBack(uint64_t value, int width);
99 int CountSetBitsFallBack(uint64_t value, int width);
100 int CountTrailingZerosFallBack(uint64_t value, int width);
101
102
103 // Implementation of intrinsics functions.
104 // TODO: The implementations could be improved for sizes different from 32bit
105 // and 64bit: we could mask the values and call the appropriate builtin.
106
107 template <typename V>
108 inline int CountLeadingSignBits(V value, int width = (sizeof(V) * 8)) {
109 #if COMPILER_HAS_BUILTIN_CLRSB
110 if (width == 32) {
111 return __builtin_clrsb(value);
112 } else if (width == 64) {
113 return __builtin_clrsbll(value);
114 }
115 #endif
116 return CountLeadingSignBitsFallBack(value, width);
117 }
118
119
120 template <typename V>
121 inline int CountLeadingZeros(V value, int width = (sizeof(V) * 8)) {
122 #if COMPILER_HAS_BUILTIN_CLZ
123 if (width == 32) {
124 return (value == 0) ? 32 : __builtin_clz(static_cast<unsigned>(value));
125 } else if (width == 64) {
126 return (value == 0) ? 64 : __builtin_clzll(value);
127 }
128 #endif
129 return CountLeadingZerosFallBack(value, width);
130 }
131
132
133 template <typename V>
134 inline int CountSetBits(V value, int width = (sizeof(V) * 8)) {
135 #if COMPILER_HAS_BUILTIN_POPCOUNT
136 if (width == 32) {
137 return __builtin_popcount(static_cast<unsigned>(value));
138 } else if (width == 64) {
139 return __builtin_popcountll(value);
140 }
141 #endif
142 return CountSetBitsFallBack(value, width);
143 }
144
145
146 template <typename V>
147 inline int CountTrailingZeros(V value, int width = (sizeof(V) * 8)) {
148 #if COMPILER_HAS_BUILTIN_CTZ
149 if (width == 32) {
150 return (value == 0) ? 32 : __builtin_ctz(static_cast<unsigned>(value));
151 } else if (width == 64) {
152 return (value == 0) ? 64 : __builtin_ctzll(value);
153 }
154 #endif
155 return CountTrailingZerosFallBack(value, width);
156 }
157
158 } // namespace vixl
159
160 #endif // VIXL_COMPILER_INTRINSICS_H
161