1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
From a2a8b560c1749293d3b6d027e20753a7ea042c80 Mon Sep 17 00:00:00 2001
From: Richard Sandiford <richard.sandiford@arm.com>
Date: Sat, 11 Nov 2023 17:28:55 +0000
Subject: [PATCH 035/157] [Backport][SME] mode-switching: Avoid quadractic list
operation
Reference: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=174ee5115a3004d3664165e9d619535b579111d4
add_seginfo chained insn information to the end of a list
by starting at the head of the list. This patch avoids the
quadraticness by keeping track of the tail pointer.
gcc/
* mode-switching.cc (add_seginfo): Replace head pointer with
a pointer to the tail pointer.
(optimize_mode_switching): Update calls accordingly.
---
gcc/mode-switching.cc | 24 ++++++++----------------
1 file changed, 8 insertions(+), 16 deletions(-)
diff --git a/gcc/mode-switching.cc b/gcc/mode-switching.cc
index 2a9f98793..6a13951c9 100644
--- a/gcc/mode-switching.cc
+++ b/gcc/mode-switching.cc
@@ -162,23 +162,14 @@ new_seginfo (int mode, rtx_insn *insn, const HARD_REG_SET ®s_live)
}
/* Add a seginfo element to the end of a list.
- HEAD is a pointer to the list beginning.
+ TAIL is a pointer to the list's null terminator.
INFO is the structure to be linked in. */
static void
-add_seginfo (struct bb_info *head, struct seginfo *info)
+add_seginfo (struct seginfo ***tail_ptr, struct seginfo *info)
{
- struct seginfo *ptr;
-
- if (head->seginfo == NULL)
- head->seginfo = info;
- else
- {
- ptr = head->seginfo;
- while (ptr->next != NULL)
- ptr = ptr->next;
- ptr->next = info;
- }
+ **tail_ptr = info;
+ *tail_ptr = &info->next;
}
/* Record in LIVE that register REG died. */
@@ -573,6 +564,7 @@ optimize_mode_switching (void)
Also compute the initial transparency settings. */
FOR_EACH_BB_FN (bb, cfun)
{
+ struct seginfo **tail_ptr = &info[bb->index].seginfo;
struct seginfo *ptr;
int last_mode = no_mode;
bool any_set_required = false;
@@ -598,7 +590,7 @@ optimize_mode_switching (void)
if (ins_pos != BB_END (bb))
ins_pos = NEXT_INSN (ins_pos);
ptr = new_seginfo (no_mode, ins_pos, live_now);
- add_seginfo (info + bb->index, ptr);
+ add_seginfo (&tail_ptr, ptr);
for (i = 0; i < no_mode; i++)
clear_mode_bit (transp[bb->index], j, i);
}
@@ -616,7 +608,7 @@ optimize_mode_switching (void)
any_set_required = true;
last_mode = mode;
ptr = new_seginfo (mode, insn, live_now);
- add_seginfo (info + bb->index, ptr);
+ add_seginfo (&tail_ptr, ptr);
for (i = 0; i < no_mode; i++)
clear_mode_bit (transp[bb->index], j, i);
}
@@ -645,7 +637,7 @@ optimize_mode_switching (void)
if (!any_set_required)
{
ptr = new_seginfo (no_mode, BB_END (bb), live_now);
- add_seginfo (info + bb->index, ptr);
+ add_seginfo (&tail_ptr, ptr);
if (last_mode != no_mode)
for (i = 0; i < no_mode; i++)
clear_mode_bit (transp[bb->index], j, i);
--
2.33.0
|
