1/* Operations on HOST_WIDE_INT.
2 Copyright (C) 1987-2017 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify it under
7the terms of the GNU General Public License as published by the Free
8Software Foundation; either version 3, or (at your option) any later
9version.
10
11GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12WARRANTY; without even the implied warranty of MERCHANTABILITY or
13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14for more details.
15
16You should have received a copy of the GNU General Public License
17along 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
35int
36floor_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 largest Y such that 2**Y >= X. */
64
65int
66ceil_log2 (unsigned HOST_WIDE_INT x)
67{
68 return 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
74int
75exact_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
85int
86ctz_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
93int
94clz_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
102int
103ffs_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
110int
111popcount_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
131HOST_WIDE_INT
132gcd (HOST_WIDE_INT a, HOST_WIDE_INT b)
133{
134 HOST_WIDE_INT x, y, z;
135
136 x = abs_hwi (a);
137 y = abs_hwi (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
152HOST_WIDE_INT
153pos_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
164HOST_WIDE_INT
165mul_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);
176 }
177
178 if (y >= 0)
179 return -pos_mul_hwi (-x, y);
180
181 return pos_mul_hwi (-x, -y);
182}
183
184/* Compute the least common multiple of two numbers A and B . */
185
186HOST_WIDE_INT
187least_common_multiple (HOST_WIDE_INT a, HOST_WIDE_INT b)
188{
189 return mul_hwi (abs_hwi (a) / gcd (a, b), abs_hwi (b));
190}
191