about summary refs log tree commit diff
path: root/sysdeps/alpha/lshift.S
blob: adbe0b8fa65d5d0fc82e2e98fc0d6d6d91723a61 (plain) (blame)
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
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
 # Alpha 21064 __mpn_lshift --

 # Copyright (C) 1994-2018 Free Software Foundation, Inc.

 # This file is part of the GNU MP Library.

 # The GNU MP Library is free software; you can redistribute it and/or modify
 # it under the terms of the GNU Lesser General Public License as published by
 # the Free Software Foundation; either version 2.1 of the License, or (at your
 # option) any later version.

 # The GNU MP Library is distributed in the hope that it will be useful, but
 # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 # or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 # License for more details.

 # You should have received a copy of the GNU Lesser General Public License
 # along with the GNU MP Library.  If not, see <http://www.gnu.org/licenses/>.


 # INPUT PARAMETERS
 # res_ptr	r16
 # s1_ptr	r17
 # size		r18
 # cnt		r19

 # This code runs at 4.8 cycles/limb on the 21064.  With infinite unrolling,
 # it would take 4 cycles/limb.  It should be possible to get down to 3
 # cycles/limb since both ldq and stq can be paired with the other used
 # instructions.  But there are many restrictions in the 21064 pipeline that
 # makes it hard, if not impossible, to get down to 3 cycles/limb:

 # 1. ldq has a 3 cycle delay, srl and sll have a 2 cycle delay.
 # 2. Only aligned instruction pairs can be paired.
 # 3. The store buffer or silo might not be able to deal with the bandwidth.

	.set	noreorder
	.set	noat
.text
	.align	3
	.globl	__mpn_lshift
	.ent	__mpn_lshift
__mpn_lshift:
	.frame	$30,0,$26,0

	s8addq	$18,$17,$17	# make r17 point at end of s1
	ldq	$4,-8($17)	# load first limb
	subq	$17,8,$17
	subq	$31,$19,$7
	s8addq	$18,$16,$16	# make r16 point at end of RES
	subq	$18,1,$18
	and	$18,4-1,$20	# number of limbs in first loop
	srl	$4,$7,$0	# compute function result

	beq	$20,.L0
	subq	$18,$20,$18

	.align	3
.Loop0:
	ldq	$3,-8($17)
	subq	$16,8,$16
	subq	$17,8,$17
	subq	$20,1,$20
	sll	$4,$19,$5
	srl	$3,$7,$6
	bis	$3,$3,$4
	bis	$5,$6,$8
	stq	$8,0($16)
	bne	$20,.Loop0

.L0:	beq	$18,.Lend

	.align	3
.Loop:	ldq	$3,-8($17)
	subq	$16,32,$16
	subq	$18,4,$18
	sll	$4,$19,$5
	srl	$3,$7,$6

	ldq	$4,-16($17)
	sll	$3,$19,$1
	bis	$5,$6,$8
	stq	$8,24($16)
	srl	$4,$7,$2

	ldq	$3,-24($17)
	sll	$4,$19,$5
	bis	$1,$2,$8
	stq	$8,16($16)
	srl	$3,$7,$6

	ldq	$4,-32($17)
	sll	$3,$19,$1
	bis	$5,$6,$8
	stq	$8,8($16)
	srl	$4,$7,$2

	subq	$17,32,$17
	bis	$1,$2,$8
	stq	$8,0($16)

	bgt	$18,.Loop

.Lend:	sll	$4,$19,$8
	stq	$8,-8($16)
	ret	$31,($26),1
	.end	__mpn_lshift