When the insn 1 and 2, 3 and 4 can be fusioned, then there is the
following sequence:
;; insn |
;; 1 | sp=sp-0x18
;; + 2 | [sp+0x10]=ra
;; 3 | [sp+0x8]=s0
;; 4 | [sp+0x0]=s1
The fusion priority of the insn 2, 3, and 4 are the same. According to
the current algorithm, since abs(0x10-0x8)<abs(0x10-0x0), the insn 2
is followed by the insn 3. It is obviously unreasonable to do so.
Therefore, when we issue the insn 3 and 4, we should consider the fusion
priority of the insn 1 instead of the insn 2. And the final instruction
sequence is as follows:
;; insn |
;; 1 | sp=sp-0x18
;; + 2 | [sp+0x10]=ra
;; 4 | [sp+0x8]=s1
;; + 3 | [sp+0x0]=s0
gcc/ChangeLog:
* haifa-sched.cc (rank_for_schedule): Likewise.
---
gcc/haifa-sched.cc | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/gcc/haifa-sched.cc b/gcc/haifa-sched.cc
index 1bc610f9a5f..0c8c2b18bd2 100644
--- a/gcc/haifa-sched.cc
+++ b/gcc/haifa-sched.cc
@@ -2640,12 +2640,18 @@ rank_for_schedule (const void *x, const void *y)
int a = INSN_FUSION_PRIORITY (tmp);
int b = INSN_FUSION_PRIORITY (tmp2);
int last = -1;
+ rtx_insn *last_insn = last_nondebug_scheduled_insn;
- if (last_nondebug_scheduled_insn
- && !NOTE_P (last_nondebug_scheduled_insn)
+ /* If last_insn can be fusioned with the previous insn, then we
+ should use the previous insn fusion priority and priority. */
+ if (last_insn && INSN_P (last_insn) && SCHED_GROUP_P (last_insn))
+ last_insn = prev_nonnote_nondebug_insn_bb (last_insn);
+
+ if (last_insn
+ && !NOTE_P (last_insn)
&& BLOCK_FOR_INSN (tmp)
- == BLOCK_FOR_INSN (last_nondebug_scheduled_insn))
- last = INSN_FUSION_PRIORITY (last_nondebug_scheduled_insn);
+ == BLOCK_FOR_INSN (last_insn))
+ last = INSN_FUSION_PRIORITY (last_insn);
if (a != last && b != last)
{
@@ -2662,9 +2668,9 @@ rank_for_schedule (const void *x, const void *y)
}
else if (a == b)
{
- gcc_assert (last_nondebug_scheduled_insn
- && !NOTE_P (last_nondebug_scheduled_insn));
- last = INSN_PRIORITY (last_nondebug_scheduled_insn);
+ gcc_assert (last_insn
+ && !NOTE_P (last_insn));
+ last = INSN_PRIORITY (last_insn);
a = abs (INSN_PRIORITY (tmp) - last);
b = abs (INSN_PRIORITY (tmp2) - last);
--
2.17.1
