From dc1969dab392661cdac1170bbb8c9f83f388580d Mon Sep 17 00:00:00 2001
From: Xionghu Luo <luoxhu@linux.ibm.com>
Date: Wed, 29 Dec 2021 20:02:12 -0600
Subject: [PATCH] loop-invariant: Don't move cold bb instructions to preheader
in RTL
gcc/ChangeLog:
2021-12-30 Xionghu Luo <luoxhu@linux.ibm.com>
* loop-invariant.c (find_invariants_bb): Check profile count
before motion.
(find_invariants_body): Add argument.
gcc/testsuite/ChangeLog:
2021-12-30 Xionghu Luo <luoxhu@linux.ibm.com>
* gcc.dg/loop-invariant-2.c: New.
---
gcc/loop-invariant.c | 17 ++++++++++++++---
gcc/testsuite/gcc.dg/loop-invariant-2.c | 20 ++++++++++++++++++++
2 files changed, 34 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/loop-invariant-2.c
diff --git a/gcc/loop-invariant.c b/gcc/loop-invariant.c
index be9515543374..d69a0c16e33b 100644
--- a/gcc/loop-invariant.c
+++ b/gcc/loop-invariant.c
@@ -1183,9 +1183,21 @@ find_invariants_insn (rtx_insn *insn, bool always_reached, bool always_executed)
call. */
static void
-find_invariants_bb (basic_block bb, bool always_reached, bool always_executed)
+find_invariants_bb (class loop *loop, basic_block bb, bool always_reached,
+ bool always_executed)
{
rtx_insn *insn;
+ basic_block preheader = loop_preheader_edge (loop)->src;
+
+ /* 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 (dump_file)
+ fprintf (dump_file, "Don't move invariant from bb: %d out of loop %d\n",
+ bb->index, loop->num);
+ return;
+ }
FOR_BB_INSNS (bb, insn)
{
@@ -1214,8 +1226,7 @@ find_invariants_body (class loop *loop, basic_block *body,
unsigned i;
for (i = 0; i < loop->num_nodes; i++)
- find_invariants_bb (body[i],
- bitmap_bit_p (always_reached, i),
+ find_invariants_bb (loop, body[i], bitmap_bit_p (always_reached, i),
bitmap_bit_p (always_executed, i));
}
diff --git a/gcc/testsuite/gcc.dg/loop-invariant-2.c b/gcc/testsuite/gcc.dg/loop-invariant-2.c
new file mode 100644
index 000000000000..df3d84585697
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/loop-invariant-2.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-loop2_invariant" } */
+
+volatile int x;
+void
+bar (int, char *, char *);
+void
+foo (int *a, int n, int k)
+{
+ int i;
+
+ for (i = 0; i < n; i++)
+ {
+ if (__builtin_expect (x, 0))
+ bar (k / 5, "one", "two");
+ a[i] = k;
+ }
+}
+
+/* { dg-final { scan-rtl-dump "Don't move invariant from bb: .*out of loop" "loop2_invariant" } } */
--
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