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expand: Add dump for costing of positive divides

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While trying to understand PR 115910 I found it was useful to print out
the two costs of doing a signed and unsigned division just like was added in
r15-3272-g3c89c41991d8e8 for popcount==1.

Bootstrapped and tested on x86_64-linux-gnu.

gcc/ChangeLog:

	* expr.cc (expand_expr_divmod): Add dump of the two costs for
	positive division.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
This commit is contained in:
Andrew Pinski 2024-09-03 18:50:37 -07:00
parent 62dd893ff8
commit dbd0eb39c6
1 changed files with 7 additions and 0 deletions
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7
gcc/expr.cc
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@ -9648,6 +9648,7 @@ expand_expr_divmod (tree_code code, machine_mode mode, tree treeop0,
end_sequence ();
unsigned uns_cost = seq_cost (uns_insns, speed_p);
unsigned sgn_cost = seq_cost (sgn_insns, speed_p);
bool was_tie = false;
/* If costs are the same then use as tie breaker the other other
factor. */
@ -9655,8 +9656,14 @@ expand_expr_divmod (tree_code code, machine_mode mode, tree treeop0,
{
uns_cost = seq_cost (uns_insns, !speed_p);
sgn_cost = seq_cost (sgn_insns, !speed_p);
was_tie = true;
}
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf(dump_file, "positive division:%s unsigned cost: %u; "
"signed cost: %u\n", was_tie ? "(needed tie breaker)":"",
uns_cost, sgn_cost);
if (uns_cost < sgn_cost || (uns_cost == sgn_cost && unsignedp))
{
emit_insn (uns_insns);