double-int.h (double_int_popcount): New inline function.

[thirdparty/gcc.git] / gcc / hwint.c

/* Operations on HOST_WIDE_INT.
   Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
   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 "diagnostic-core.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 >= (unsigned HOST_WIDE_INT) 1 << (t + 64))
      t += 64;
  if (HOST_BITS_PER_WIDE_INT > 32)
    if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 32))
      t += 32;
  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 16))
    t += 16;
  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 8))
    t += 8;
  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 4))
    t += 4;
  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 2))
    t += 2;
  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 1))
    t += 1;

  return t;
}

/* Given X, an unsigned number, return the largest Y such that 2**Y >= X.  */

int
ceil_log2 (unsigned HOST_WIDE_INT x)
{
  return 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 (x != (x & -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 (x & -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 (x & -x);
}

/* Return the number of set bits in X.  */

int
popcount_hwi (unsigned HOST_WIDE_INT x)
{
  int i, ret = 0;

  for (i = 0; i < sizeof (x); i += 1)
    {
      ret += x & 1;
      x >>= 1;
    }

  return ret;
}

#endif /* GCC_VERSION < 3004 */

/* Compute the absolute value of X.  */

HOST_WIDE_INT
abs_hwi (HOST_WIDE_INT x)
{
  gcc_checking_assert (x != HOST_WIDE_INT_MIN);
  return x >= 0 ? x : -x;
}

/* Compute the absolute value of X as an unsigned type.  */

unsigned HOST_WIDE_INT
absu_hwi (HOST_WIDE_INT x)
{
  return x >= 0 ? (unsigned HOST_WIDE_INT)x : -(unsigned HOST_WIDE_INT)x;
}

/* 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));
}