From 3443ed7be91c267460d79845004008a27bcb7f39 Mon Sep 17 00:00:00 2001
From: zhaowenyu <804544223@qq.com>
Date: Fri, 24 Jun 2022 01:50:55 +0800
Subject: [PATCH] [loop-invariant] Add option to limit count check in
 loop-invariant motion

backport Optimize for loop invariant motion introduce performance recession
on 500.perlbench_r(-3.06%), 525.x264_r(-0.76%).So option -flim-count-check to
limits its impact.
---
 gcc/common.opt                          | 5 +++++
 gcc/loop-invariant.c                    | 2 +-
 gcc/testsuite/gcc.dg/loop-invariant-2.c | 2 +-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/gcc/common.opt b/gcc/common.opt
index b5ea3c7a127..738311fa21f 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -3511,4 +3511,9 @@ fipa-ra
 Common Report Var(flag_ipa_ra) Optimization
 Use caller save register across calls if possible.
 
+flim-count-check
+Common Report Var(flag_lim_count_check) Init(1) Optimization
+Limit count check in loop-invariant.
+
+
 ; This comment is to ensure we retain the blank line above.
diff --git a/gcc/loop-invariant.c b/gcc/loop-invariant.c
index 24b9bcb11dc..262683f0189 100644
--- a/gcc/loop-invariant.c
+++ b/gcc/loop-invariant.c
@@ -1192,7 +1192,7 @@ find_invariants_bb (class loop *loop, basic_block bb, bool always_reached,
 
   /* Don't move insn of cold BB out of loop to preheader to reduce calculations
      and register live range in hot loop with cold BB.  */
-  if (!always_executed && preheader->count > bb->count)
+  if (!always_executed && preheader->count > bb->count && flag_lim_count_check)
     {
       if (dump_file)
 	fprintf (dump_file, "Don't move invariant from bb: %d out of loop %d\n",
diff --git a/gcc/testsuite/gcc.dg/loop-invariant-2.c b/gcc/testsuite/gcc.dg/loop-invariant-2.c
index df3d8458569..3bfaecc818a 100644
--- a/gcc/testsuite/gcc.dg/loop-invariant-2.c
+++ b/gcc/testsuite/gcc.dg/loop-invariant-2.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-rtl-loop2_invariant" } */
+/* { dg-options "-O2 -fdump-rtl-loop2_invariant -flim-count-check" } */
 
 volatile int x;
 void
-- 
Gitee