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tree-ssa-loop-niter.c (inverse): Count in HOST_WIDE_INT if possible.

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* tree-ssa-loop-niter.c (inverse): Count in HOST_WIDE_INT if possible.
	Use integer for loop counter.
	(num_ending_zeros): New function.
	(number_of_iterations_cond): Use num_ending_zeros.

From-SVN: r89438
This commit is contained in:
Zdenek Dvorak 2004-10-22 12:31:23 +02:00 committed by Zdenek Dvorak
parent aed305a929
commit 26630a99da
2 changed files with 84 additions and 25 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2004-10-22 Zdenek Dvorak <dvorakz@suse.cz>
* tree-ssa-loop-niter.c (inverse): Count in HOST_WIDE_INT if possible.
Use integer for loop counter.
(num_ending_zeros): New function.
(number_of_iterations_cond): Use num_ending_zeros.
2004-10-21 Aldy Hernandez <aldyh@redhat.com>
* config.gcc: Add support for --enable-e500_double.

102
gcc/tree-ssa-loop-niter.c
View File

@ -83,22 +83,83 @@ nonzero_p (tree arg)
return (TREE_INT_CST_LOW (arg) != 0 || TREE_INT_CST_HIGH (arg) != 0);
}
/* Returns number of zeros at the end of binary representation of X.
??? Use ffs if available? */
static tree
num_ending_zeros (tree x)
{
unsigned HOST_WIDE_INT fr, nfr;
unsigned num, abits;
tree type = TREE_TYPE (x);
if (TREE_INT_CST_LOW (x) == 0)
{
num = HOST_BITS_PER_WIDE_INT;
fr = TREE_INT_CST_HIGH (x);
}
else
{
num = 0;
fr = TREE_INT_CST_LOW (x);
}
for (abits = HOST_BITS_PER_WIDE_INT / 2; abits; abits /= 2)
{
nfr = fr >> abits;
if (nfr << abits == fr)
{
num += abits;
fr = nfr;
}
}
if (num > TYPE_PRECISION (type))
num = TYPE_PRECISION (type);
return build_int_cst_type (type, num);
}
/* Returns inverse of X modulo 2^s, where MASK = 2^s-1. */
static tree
inverse (tree x, tree mask)
{
tree type = TREE_TYPE (x);
tree ctr = EXEC_BINARY (RSHIFT_EXPR, type, mask, integer_one_node);
tree rslt = build_int_cst_type (type, 1);
tree rslt;
unsigned ctr = tree_floor_log2 (mask);
while (nonzero_p (ctr))
if (TYPE_PRECISION (type) <= HOST_BITS_PER_WIDE_INT)
{
rslt = EXEC_BINARY (MULT_EXPR, type, rslt, x);
unsigned HOST_WIDE_INT ix;
unsigned HOST_WIDE_INT imask;
unsigned HOST_WIDE_INT irslt = 1;
gcc_assert (cst_and_fits_in_hwi (x));
gcc_assert (cst_and_fits_in_hwi (mask));
ix = int_cst_value (x);
imask = int_cst_value (mask);
for (; ctr; ctr--)
{
irslt *= ix;
ix *= ix;
}
irslt &= imask;
rslt = build_int_cst_type (type, irslt);
}
else
{
rslt = build_int_cst_type (type, 1);
for (; ctr; ctr--)
{
rslt = EXEC_BINARY (MULT_EXPR, type, rslt, x);
x = EXEC_BINARY (MULT_EXPR, type, x, x);
}
rslt = EXEC_BINARY (BIT_AND_EXPR, type, rslt, mask);
x = EXEC_BINARY (MULT_EXPR, type, x, x);
x = EXEC_BINARY (BIT_AND_EXPR, type, x, mask);
ctr = EXEC_BINARY (RSHIFT_EXPR, type, ctr, integer_one_node);
}
return rslt;
@ -129,6 +190,7 @@ number_of_iterations_cond (tree type, tree base0, tree step0,
tree assumptions = boolean_true_node;
tree noloop_assumptions = boolean_false_node;
tree niter_type, signed_niter_type;
tree bits;
/* The meaning of these assumptions is this:
if !assumptions
@ -350,26 +412,16 @@ number_of_iterations_cond (tree type, tree base0, tree step0,
base1 = fold_convert (niter_type, base1);
step0 = fold_convert (niter_type, step0);
/* Let nsd (s, size of mode) = d. If d does not divide c, the loop
/* Let nsd (step, size of mode) = d. If d does not divide c, the loop
is infinite. Otherwise, the number of iterations is
(inverse(s/d) * (c/d)) mod (size of mode/d). */
s = step0;
d = integer_one_node;
bound = build_int_cst (niter_type, -1);
while (1)
{
tmp = EXEC_BINARY (BIT_AND_EXPR, niter_type, s,
build_int_cst (niter_type, 1));
if (nonzero_p (tmp))
break;
s = EXEC_BINARY (RSHIFT_EXPR, niter_type, s,
build_int_cst (niter_type, 1));
d = EXEC_BINARY (LSHIFT_EXPR, niter_type, d,
build_int_cst (niter_type, 1));
bound = EXEC_BINARY (RSHIFT_EXPR, niter_type, bound,
build_int_cst (niter_type, 1));
}
bits = num_ending_zeros (step0);
d = EXEC_BINARY (LSHIFT_EXPR, niter_type,
build_int_cst_type (niter_type, 1), bits);
s = EXEC_BINARY (RSHIFT_EXPR, niter_type, step0, bits);
bound = EXEC_BINARY (RSHIFT_EXPR, niter_type,
build_int_cst (niter_type, -1),
bits);
assumption = fold (build2 (FLOOR_MOD_EXPR, niter_type, base1, d));
assumption = fold (build2 (EQ_EXPR, boolean_type_node,