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From: "rvmallad at amazon dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/107409] Perf loss ~5% on 519.lbm_r SPEC
 cpu2017 benchmark with r10-5090-ga9a4edf0e71bba
Date: Thu, 01 Dec 2022 06:54:55 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107409

--- Comment #9 from Rama Malladi <rvmallad at amazon dot com> ---
(In reply to Martin Li=C5=A1ka from comment #3)
> Can you please share perf-profile before and after the revision?
>=20
> Note I can't see it for Altra aarch64 CPU:
> https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=3D633.477.0&plot.
> 1=3D683.477.0&plot.2=3D664.477.0&plot.3=3D648.477.0&plot.4=3D618.477.0&pl=
ot.5=3D605.
> 477.0&plot.6=3D759.477.0&plot.7=3D584.477.0&
>=20
> However, there are huge changes in between GCC 6/7 and a newer releases.
> Note the benchmark is pretty small and very sensitive to instruction cach=
es.

Hi, I got IPC data for baseline version of compiler and with this patch
reverted.

This is on Graviton3 processor machine, executing 1-copy rate run of 519.lb=
m_r.

Baseline: Compiler commit ID: f896c13489d22b30d01257bc8316ab97b3359d1c
Cycles:            148,489,372,938
Instructions:      382,748,379,257
IPC:               2.58

Baseline with code change in a9a4edf0e71bbac9f1b5dcecdcf9250111d16889 rever=
ted.

$ git diff gcc/tree-cfg.cc
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index d982988048f..736432713fe 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -9984,7 +9984,7 @@ execute_fixup_cfg (void)
     }
   if (scale)
     {
-      update_max_bb_count ();
+//      update_max_bb_count ();
       compute_function_frequency ();
     }

Cycles:            140,937,228,769
Instructions:      368,881,714,982
IPC:               2.62

>From the above, I do see the instructions executed are higher for the basel=
ine
compiler code-gen vs. the one with patch reverted. Can you please look into=
 the
code-gen and let me know if you find some perf opportunity with this patch
revert? Thank you.=