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/* Fold GENERIC expressions.
Copyright (C) 2003 Free Software Foundation, Inc.
Contributed by Sebastian Pop <s.pop@laposte.net>
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 2, 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 COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "errors.h"
#include "ggc.h"
#include "tree.h"
#include "tree-fold-const.h"
/* Least common multiple. */
tree
tree_fold_lcm (tree a,
tree b)
{
tree pgcd;
#if defined ENABLE_CHECKING
if (TREE_CODE (a) != INTEGER_CST
|| TREE_CODE (b) != INTEGER_CST)
abort ();
#endif
if (integer_onep (a))
return b;
if (integer_onep (b))
return a;
if (integer_zerop (a)
|| integer_zerop (b))
return integer_zero_node;
pgcd = tree_fold_gcd (a, b);
if (integer_onep (pgcd))
return tree_fold_multiply (integer_type_node, a, b);
else
return tree_fold_multiply
(integer_type_node, pgcd,
tree_fold_lcm (tree_fold_exact_div (integer_type_node, a, pgcd),
tree_fold_exact_div (integer_type_node, b, pgcd)));
}
/* Greatest common divisor. */
tree
tree_fold_gcd (tree a,
tree b)
{
tree a_mod_b;
tree type = TREE_TYPE (a);
#if defined ENABLE_CHECKING
if (TREE_CODE (a) != INTEGER_CST
|| TREE_CODE (b) != INTEGER_CST)
abort ();
#endif
if (integer_zerop (a))
return b;
if (integer_zerop (b))
return a;
if (tree_int_cst_sgn (a) == -1)
a = tree_fold_multiply (type, a,
convert (type, integer_minus_one_node));
if (tree_int_cst_sgn (b) == -1)
b = tree_fold_multiply (type, b,
convert (type, integer_minus_one_node));
while (1)
{
a_mod_b = fold (build (CEIL_MOD_EXPR, type, a, b));
if (!TREE_INT_CST_LOW (a_mod_b)
&& !TREE_INT_CST_HIGH (a_mod_b))
return b;
a = b;
b = a_mod_b;
}
}
/* Bezout: Let a1 and a2 be two integers; there exist two integers u11
and u12 such that,
| u11 * a1 + u12 * a2 = gcd (a1, a2).
This function computes the greatest common divisor using the
Blankinship algorithm. The gcd is returned, and the coefficients
of the unimodular matrix U are (u11, u12, u21, u22) such that,
| U.A = S
| (u11 u12) (a1) = (gcd)
| (u21 u22) (a2) (0)
FIXME: Use lambda_..._hermite for implementing this function.
*/
tree
tree_fold_bezout (tree a1,
tree a2,
tree *u11, tree *u12,
tree *u21, tree *u22)
{
tree s1, s2;
/* Initialize S with the coefficients of A. */
s1 = a1;
s2 = a2;
/* Initialize the U matrix */
*u11 = integer_one_node;
*u12 = integer_zero_node;
*u21 = integer_zero_node;
*u22 = integer_one_node;
if (integer_zerop (a1)
|| integer_zerop (a2))
return integer_zero_node;
while (!integer_zerop (s2))
{
int sign;
tree z, zu21, zu22, zs2;
sign = tree_int_cst_sgn (s1) * tree_int_cst_sgn (s2);
z = tree_fold_floor_div (integer_type_node,
tree_fold_abs (integer_type_node, s1),
tree_fold_abs (integer_type_node, s2));
zu21 = tree_fold_multiply (integer_type_node, z, *u21);
zu22 = tree_fold_multiply (integer_type_node, z, *u22);
zs2 = tree_fold_multiply (integer_type_node, z, s2);
/* row1 -= z * row2. */
if (sign < 0)
{
*u11 = tree_fold_plus (integer_type_node, *u11, zu21);
*u12 = tree_fold_plus (integer_type_node, *u12, zu22);
s1 = tree_fold_plus (integer_type_node, s1, zs2);
}
else if (sign > 0)
{
*u11 = tree_fold_minus (integer_type_node, *u11, zu21);
*u12 = tree_fold_minus (integer_type_node, *u12, zu22);
s1 = tree_fold_minus (integer_type_node, s1, zs2);
}
else
/* Should not happen. */
abort ();
/* Interchange row1 and row2. */
{
tree flip;
flip = *u11;
*u11 = *u21;
*u21 = flip;
flip = *u12;
*u12 = *u22;
*u22 = flip;
flip = s1;
s1 = s2;
s2 = flip;
}
}
if (tree_int_cst_sgn (s1) < 0)
{
*u11 = tree_fold_multiply (integer_type_node, *u11,
integer_minus_one_node);
*u12 = tree_fold_multiply (integer_type_node, *u12,
integer_minus_one_node);
s1 = tree_fold_multiply (integer_type_node, s1, integer_minus_one_node);
}
return s1;
}
/* The factorial. */
tree
tree_fold_factorial (tree f)
{
if (tree_int_cst_sgn (f) <= 0)
return integer_one_node;
else
return tree_fold_multiply
(integer_type_node, f,
tree_fold_factorial (tree_fold_minus
(integer_type_node, f, integer_one_node)));
}
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