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/* Operations on HOST_WIDE_INT.
Copyright (C) 1987-2024 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#if GCC_VERSION < 3004
/* The functions clz_hwi, ctz_hwi, ffs_hwi, floor_log2, ceil_log2,
and exact_log2 are defined as inline functions in hwint.h
if GCC_VERSION >= 3004.
The definitions here are used for older versions of GCC and
non-GCC bootstrap compilers. */
/* Given X, an unsigned number, return the largest int Y such that 2**Y <= X.
If X is 0, return -1. */
int
floor_log2 (unsigned HOST_WIDE_INT x)
{
int t = 0;
if (x == 0)
return -1;
if (HOST_BITS_PER_WIDE_INT > 64)
if (x >= HOST_WIDE_INT_1U << (t + 64))
t += 64;
if (HOST_BITS_PER_WIDE_INT > 32)
if (x >= HOST_WIDE_INT_1U << (t + 32))
t += 32;
if (x >= HOST_WIDE_INT_1U << (t + 16))
t += 16;
if (x >= HOST_WIDE_INT_1U << (t + 8))
t += 8;
if (x >= HOST_WIDE_INT_1U << (t + 4))
t += 4;
if (x >= HOST_WIDE_INT_1U << (t + 2))
t += 2;
if (x >= HOST_WIDE_INT_1U << (t + 1))
t += 1;
return t;
}
/* Given X, an unsigned number, return the least Y such that 2**Y >= X. */
int
ceil_log2 (unsigned HOST_WIDE_INT x)
{
return x == 0 ? 0 : floor_log2 (x - 1) + 1;
}
/* Return the logarithm of X, base 2, considering X unsigned,
if X is a power of 2. Otherwise, returns -1. */
int
exact_log2 (unsigned HOST_WIDE_INT x)
{
if (!pow2p_hwi (x))
return -1;
return floor_log2 (x);
}
/* Given X, an unsigned number, return the number of least significant bits
that are zero. When X == 0, the result is the word size. */
int
ctz_hwi (unsigned HOST_WIDE_INT x)
{
return x ? floor_log2 (least_bit_hwi (x)) : HOST_BITS_PER_WIDE_INT;
}
/* Similarly for most significant bits. */
int
clz_hwi (unsigned HOST_WIDE_INT x)
{
return HOST_BITS_PER_WIDE_INT - 1 - floor_log2 (x);
}
/* Similar to ctz_hwi, except that the least significant bit is numbered
starting from 1, and X == 0 yields 0. */
int
ffs_hwi (unsigned HOST_WIDE_INT x)
{
return 1 + floor_log2 (least_bit_hwi (x));
}
/* Return the number of set bits in X. */
int
popcount_hwi (unsigned HOST_WIDE_INT x)
{
int i, ret = 0;
size_t bits = sizeof (x) * CHAR_BIT;
for (i = 0; i < bits; i += 1)
{
ret += x & 1;
x >>= 1;
}
return ret;
}
#endif /* GCC_VERSION < 3004 */
/* Compute the greatest common divisor of two numbers A and B using
Euclid's algorithm. */
HOST_WIDE_INT
gcd (HOST_WIDE_INT a, HOST_WIDE_INT b)
{
HOST_WIDE_INT x, y, z;
x = abs_hwi (a);
y = abs_hwi (b);
while (x > 0)
{
z = y % x;
y = x;
x = z;
}
return y;
}
/* For X and Y positive integers, return X multiplied by Y and check
that the result does not overflow. */
HOST_WIDE_INT
pos_mul_hwi (HOST_WIDE_INT x, HOST_WIDE_INT y)
{
if (x != 0)
gcc_checking_assert ((HOST_WIDE_INT_MAX) / x >= y);
return x * y;
}
/* Return X multiplied by Y and check that the result does not
overflow. */
HOST_WIDE_INT
mul_hwi (HOST_WIDE_INT x, HOST_WIDE_INT y)
{
gcc_checking_assert (x != HOST_WIDE_INT_MIN
&& y != HOST_WIDE_INT_MIN);
if (x >= 0)
{
if (y >= 0)
return pos_mul_hwi (x, y);
return -pos_mul_hwi (x, -y);
}
if (y >= 0)
return -pos_mul_hwi (-x, y);
return pos_mul_hwi (-x, -y);
}
/* Compute the least common multiple of two numbers A and B . */
HOST_WIDE_INT
least_common_multiple (HOST_WIDE_INT a, HOST_WIDE_INT b)
{
return mul_hwi (abs_hwi (a) / gcd (a, b), abs_hwi (b));
}
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