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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.
This commit is contained in:
Xionghu Luo 2021-12-29 20:02:12 -06:00
parent be475aa0aa
commit dc1969dab3
2 changed files with 34 additions and 3 deletions
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17
gcc/loop-invariant.c
View File

@ -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));
}

20
gcc/testsuite/gcc.dg/loop-invariant-2.c Normal file
View File

@ -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" } } */