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IBM zSystems: Do not propagate scheduler state across basic blocks [PR108102]

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So far we propagate scheduler state across basic blocks within EBBs and
reset the state otherwise.  In certain circumstances the entry block of
an EBB might be empty, i.e., no_real_insns_p is true.  In those cases
scheduler state is not reset and subsequently wrong state is propagated
to following blocks of the same EBB.

Since the performance benefit of tracking state across basic blocks is
questionable on modern hardware, simply reset the state for each basic
block.

Fix also resetting f{p,x}d_longrunning.

gcc/ChangeLog:

	PR target/108102
	* config/s390/s390.cc (s390_bb_fallthru_entry_likely): Remove.
	(struct s390_sched_state): Initialise to zero.
	(s390_sched_variable_issue): For better debuggability also emit
	the current side.
	(s390_sched_init): Unconditionally reset scheduler state.
This commit is contained in:
Stefan Schulze Frielinghaus 2023-02-13 15:33:38 +01:00
parent 6995ac6f98
commit 452db716d8
1 changed files with 7 additions and 35 deletions
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42
gcc/config/s390/s390.cc
View file

@ -14977,29 +14977,6 @@ s390_z10_prevent_earlyload_conflicts (rtx_insn **ready, int *nready_p)
ready[0] = tmp;
}
/* Returns TRUE if BB is entered via a fallthru edge and all other
incoming edges are less than likely. */
static bool
s390_bb_fallthru_entry_likely (basic_block bb)
{
edge e, fallthru_edge;
edge_iterator ei;
if (!bb)
return false;
fallthru_edge = find_fallthru_edge (bb->preds);
if (!fallthru_edge)
return false;
FOR_EACH_EDGE (e, ei, bb->preds)
if (e != fallthru_edge
&& e->probability >= profile_probability::likely ())
return false;
return true;
}
struct s390_sched_state
{
/* Number of insns in the group. */
@ -15010,7 +14987,7 @@ struct s390_sched_state
bool group_of_two;
} s390_sched_state;
static struct s390_sched_state sched_state = {0, 1, false};
static struct s390_sched_state sched_state;
#define S390_SCHED_ATTR_MASK_CRACKED 0x1
#define S390_SCHED_ATTR_MASK_EXPANDED 0x2
@ -15510,7 +15487,7 @@ s390_sched_variable_issue (FILE *file, int verbose, rtx_insn *insn, int more)
s390_get_unit_mask (insn, &units);
fprintf (file, ";;\t\tBACKEND: units on this side unused for: ");
fprintf (file, ";;\t\tBACKEND: units on this side (%d) unused for: ", sched_state.side);
for (j = 0; j < units; j++)
fprintf (file, "%d:%d ", j,
last_scheduled_unit_distance[j][sched_state.side]);
@ -15548,17 +15525,12 @@ s390_sched_init (FILE *file ATTRIBUTE_UNUSED,
current_sched_info->prev_head is the insn before the first insn of the
block of insns to be scheduled.
*/
rtx_insn *insn = current_sched_info->prev_head
? NEXT_INSN (current_sched_info->prev_head) : NULL;
basic_block bb = insn ? BLOCK_FOR_INSN (insn) : NULL;
if (s390_tune < PROCESSOR_2964_Z13 || !s390_bb_fallthru_entry_likely (bb))
{
last_scheduled_insn = NULL;
memset (last_scheduled_unit_distance, 0,
last_scheduled_insn = NULL;
memset (last_scheduled_unit_distance, 0,
MAX_SCHED_UNITS * NUM_SIDES * sizeof (int));
sched_state.group_state = 0;
sched_state.group_of_two = false;
}
memset (fpd_longrunning, 0, NUM_SIDES * sizeof (int));
memset (fxd_longrunning, 0, NUM_SIDES * sizeof (int));
sched_state = {};
}
/* This target hook implementation for TARGET_LOOP_UNROLL_ADJUST calculates