From dbd0eb39c690f80e7a9bb7697aaa3f85ff4dbadd Mon Sep 17 00:00:00 2001
From: Andrew Pinski <quic_apinski@quicinc.com>
Date: Tue, 3 Sep 2024 18:50:37 -0700
Subject: [PATCH] expand: Add dump for costing of positive divides
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>
---
gcc/expr.cc | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/gcc/expr.cc b/gcc/expr.cc
index 320be8b17a13..7a471f20e794 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -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);
--
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