1 | /* Operations on HOST_WIDE_INT. |
2 | Copyright (C) 1987-2023 Free Software Foundation, Inc. |
3 | |
4 | This file is part of GCC. |
5 | |
6 | GCC is free software; you can redistribute it and/or modify it under |
7 | the terms of the GNU General Public License as published by the Free |
8 | Software Foundation; either version 3, or (at your option) any later |
9 | version. |
10 | |
11 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or |
13 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
14 | for more details. |
15 | |
16 | You should have received a copy of the GNU General Public License |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ |
19 | |
20 | #include "config.h" |
21 | #include "system.h" |
22 | #include "coretypes.h" |
23 | |
24 | #if GCC_VERSION < 3004 |
25 | |
26 | /* The functions clz_hwi, ctz_hwi, ffs_hwi, floor_log2, ceil_log2, |
27 | and exact_log2 are defined as inline functions in hwint.h |
28 | if GCC_VERSION >= 3004. |
29 | The definitions here are used for older versions of GCC and |
30 | non-GCC bootstrap compilers. */ |
31 | |
32 | /* Given X, an unsigned number, return the largest int Y such that 2**Y <= X. |
33 | If X is 0, return -1. */ |
34 | |
35 | int |
36 | floor_log2 (unsigned HOST_WIDE_INT x) |
37 | { |
38 | int t = 0; |
39 | |
40 | if (x == 0) |
41 | return -1; |
42 | |
43 | if (HOST_BITS_PER_WIDE_INT > 64) |
44 | if (x >= HOST_WIDE_INT_1U << (t + 64)) |
45 | t += 64; |
46 | if (HOST_BITS_PER_WIDE_INT > 32) |
47 | if (x >= HOST_WIDE_INT_1U << (t + 32)) |
48 | t += 32; |
49 | if (x >= HOST_WIDE_INT_1U << (t + 16)) |
50 | t += 16; |
51 | if (x >= HOST_WIDE_INT_1U << (t + 8)) |
52 | t += 8; |
53 | if (x >= HOST_WIDE_INT_1U << (t + 4)) |
54 | t += 4; |
55 | if (x >= HOST_WIDE_INT_1U << (t + 2)) |
56 | t += 2; |
57 | if (x >= HOST_WIDE_INT_1U << (t + 1)) |
58 | t += 1; |
59 | |
60 | return t; |
61 | } |
62 | |
63 | /* Given X, an unsigned number, return the least Y such that 2**Y >= X. */ |
64 | |
65 | int |
66 | ceil_log2 (unsigned HOST_WIDE_INT x) |
67 | { |
68 | return x == 0 ? 0 : floor_log2 (x - 1) + 1; |
69 | } |
70 | |
71 | /* Return the logarithm of X, base 2, considering X unsigned, |
72 | if X is a power of 2. Otherwise, returns -1. */ |
73 | |
74 | int |
75 | exact_log2 (unsigned HOST_WIDE_INT x) |
76 | { |
77 | if (!pow2p_hwi (x)) |
78 | return -1; |
79 | return floor_log2 (x); |
80 | } |
81 | |
82 | /* Given X, an unsigned number, return the number of least significant bits |
83 | that are zero. When X == 0, the result is the word size. */ |
84 | |
85 | int |
86 | ctz_hwi (unsigned HOST_WIDE_INT x) |
87 | { |
88 | return x ? floor_log2 (least_bit_hwi (x)) : HOST_BITS_PER_WIDE_INT; |
89 | } |
90 | |
91 | /* Similarly for most significant bits. */ |
92 | |
93 | int |
94 | clz_hwi (unsigned HOST_WIDE_INT x) |
95 | { |
96 | return HOST_BITS_PER_WIDE_INT - 1 - floor_log2 (x); |
97 | } |
98 | |
99 | /* Similar to ctz_hwi, except that the least significant bit is numbered |
100 | starting from 1, and X == 0 yields 0. */ |
101 | |
102 | int |
103 | ffs_hwi (unsigned HOST_WIDE_INT x) |
104 | { |
105 | return 1 + floor_log2 (least_bit_hwi (x)); |
106 | } |
107 | |
108 | /* Return the number of set bits in X. */ |
109 | |
110 | int |
111 | popcount_hwi (unsigned HOST_WIDE_INT x) |
112 | { |
113 | int i, ret = 0; |
114 | size_t bits = sizeof (x) * CHAR_BIT; |
115 | |
116 | for (i = 0; i < bits; i += 1) |
117 | { |
118 | ret += x & 1; |
119 | x >>= 1; |
120 | } |
121 | |
122 | return ret; |
123 | } |
124 | |
125 | #endif /* GCC_VERSION < 3004 */ |
126 | |
127 | |
128 | /* Compute the greatest common divisor of two numbers A and B using |
129 | Euclid's algorithm. */ |
130 | |
131 | HOST_WIDE_INT |
132 | gcd (HOST_WIDE_INT a, HOST_WIDE_INT b) |
133 | { |
134 | HOST_WIDE_INT x, y, z; |
135 | |
136 | x = abs_hwi (x: a); |
137 | y = abs_hwi (x: b); |
138 | |
139 | while (x > 0) |
140 | { |
141 | z = y % x; |
142 | y = x; |
143 | x = z; |
144 | } |
145 | |
146 | return y; |
147 | } |
148 | |
149 | /* For X and Y positive integers, return X multiplied by Y and check |
150 | that the result does not overflow. */ |
151 | |
152 | HOST_WIDE_INT |
153 | pos_mul_hwi (HOST_WIDE_INT x, HOST_WIDE_INT y) |
154 | { |
155 | if (x != 0) |
156 | gcc_checking_assert ((HOST_WIDE_INT_MAX) / x >= y); |
157 | |
158 | return x * y; |
159 | } |
160 | |
161 | /* Return X multiplied by Y and check that the result does not |
162 | overflow. */ |
163 | |
164 | HOST_WIDE_INT |
165 | mul_hwi (HOST_WIDE_INT x, HOST_WIDE_INT y) |
166 | { |
167 | gcc_checking_assert (x != HOST_WIDE_INT_MIN |
168 | && y != HOST_WIDE_INT_MIN); |
169 | |
170 | if (x >= 0) |
171 | { |
172 | if (y >= 0) |
173 | return pos_mul_hwi (x, y); |
174 | |
175 | return -pos_mul_hwi (x, y: -y); |
176 | } |
177 | |
178 | if (y >= 0) |
179 | return -pos_mul_hwi (x: -x, y); |
180 | |
181 | return pos_mul_hwi (x: -x, y: -y); |
182 | } |
183 | |
184 | /* Compute the least common multiple of two numbers A and B . */ |
185 | |
186 | HOST_WIDE_INT |
187 | least_common_multiple (HOST_WIDE_INT a, HOST_WIDE_INT b) |
188 | { |
189 | return mul_hwi (x: abs_hwi (x: a) / gcd (a, b), y: abs_hwi (x: b)); |
190 | } |
191 | |