https://gcc.gnu.org/g:3c89c41991d8e84d28d3aba22bb06b2712a29523
commit r15-3272-g3c89c41991d8e84d28d3aba22bb06b2712a29523
Author: Andrew Pinski <quic_apin...@quicinc.com>
Date: Mon Aug 26 15:14:24 2024 -0700
expand: Add debug dump on the cost for `popcount==1` expand
While working on PR 114224, I found it would be useful to dump the
different costs of the expansion to make easier to understand why one
was chosen over the other.
Changes since v1:
* v2: make the dump a single line
Bootstrapped and tested on x86_64-linux-gnu.
Build and tested for aarch64-linux-gnu.
gcc/ChangeLog:
* internal-fn.cc (expand_POPCOUNT): Dump the costs for
the two choices.
Diff:
---
gcc/internal-fn.cc | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/gcc/internal-fn.cc b/gcc/internal-fn.cc
index 89da13b38ce1..78997ef056ad 100644
--- a/gcc/internal-fn.cc
+++ b/gcc/internal-fn.cc
@@ -5351,6 +5351,11 @@ expand_POPCOUNT (internal_fn fn, gcall *stmt)
unsigned popcount_cost = (seq_cost (popcount_insns, speed_p)
+ seq_cost (popcount_cmp_insns, speed_p));
unsigned cmp_cost = seq_cost (cmp_insns, speed_p);
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf(dump_file, "popcount == 1: popcount cost: %u; cmp cost: %u\n",
+ popcount_cost, cmp_cost);
+
if (popcount_cost <= cmp_cost)
emit_insn (popcount_insns);
else
