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cse.c (fold_rtx): When arg1 has a constant equivalent...

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* cse.c (fold_rtx) <case RTX_COMM_COMPARE, RTX_COMPARE>: When arg1
	has a constant equivalent, iterate over equivalents for arg0,
	calling simplify_relational_operation and if there's a result
	cheaper than X, apply fold_rtx and return the result.

From-SVN: r110481
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Hans-Peter Nilsson 2006-02-01 21:15:54 +00:00 • committed by Hans-Peter Nilsson
parent 46fd0f8c24
commit 08678f511c
2 changed files with 58 additions and 0 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2006-02-01 Hans-Peter Nilsson <hp@axis.com>
* cse.c (fold_rtx) <case RTX_COMM_COMPARE, RTX_COMPARE>: When arg1
has a constant equivalent, iterate over equivalents for arg0,
calling simplify_relational_operation and if there's a result
cheaper than X, apply fold_rtx and return the result.
2006-02-01 Jan Hubicka <jh@suse.cz>
* opts.c (no_unit_at_a_time_default): New global variable.

51
gcc/cse.c
View file

@ -3981,6 +3981,57 @@ fold_rtx (rtx x, rtx insn)
comparison. */
if (const_arg0 == 0 || const_arg1 == 0)
{
if (const_arg1 != NULL)
{
rtx cheapest_simplification;
int cheapest_cost;
rtx simp_result;
struct table_elt *p;
/* See if we can find an equivalent of folded_arg0
that gets us a cheaper expression, possibly a
constant through simplifications. */
p = lookup (folded_arg0, SAFE_HASH (folded_arg0, mode_arg0),
mode_arg0);
if (p != NULL)
{
cheapest_simplification = x;
cheapest_cost = COST (x);
for (p = p->first_same_value; p != NULL; p = p->next_same_value)
{
int cost;
/* If the entry isn't valid, skip it. */
if (! exp_equiv_p (p->exp, p->exp, 1, false))
continue;
/* Try to simplify using this equivalence. */
simp_result
= simplify_relational_operation (code, mode,
mode_arg0,
p->exp,
const_arg1);
if (simp_result == NULL)
continue;
cost = COST (simp_result);
if (cost < cheapest_cost)
{
cheapest_cost = cost;
cheapest_simplification = simp_result;
}
}
/* If we have a cheaper expression now, use that
and try folding it further, from the top. */
if (cheapest_simplification != x)
return fold_rtx (cheapest_simplification, insn);
}
}
/* Some addresses are known to be nonzero. We don't know
their sign, but equality comparisons are known. */
if (const_arg1 == const0_rtx