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authorRichard Henderson <rth@twiddle.net>2014-02-12 06:54:57 -0800
committerRichard Henderson <rth@twiddle.net>2014-02-12 07:00:06 -0800
commit68b7efaadb1b6045a56277ea62d324c20ac0b633 (patch)
tree07b51c9866373430373fb90b252d46c23cc1707e /sysdeps/alpha/alphaev5
parent8fd7b0d5591e59ed5cb3078b351bd49314a66cef (diff)
downloadglibc-68b7efaadb1b6045a56277ea62d324c20ac0b633.tar.gz
glibc-68b7efaadb1b6045a56277ea62d324c20ac0b633.tar.xz
glibc-68b7efaadb1b6045a56277ea62d324c20ac0b633.zip
Relocate alpha from ports to libc
Also fixed the following whitespace nits to satisfy the push:

sysdeps/alpha/alphaev6/memset.S:142: space before tab in indent.
sysdeps/alpha/configure:1: new blank line at EOF.
sysdeps/alpha/fpu/e_sqrt.c:126: space before tab in indent.
sysdeps/alpha/preconfigure:1: new blank line at EOF.
sysdeps/unix/sysv/linux/alpha/syscalls.list:1: new blank line at EOF.
Diffstat (limited to 'sysdeps/alpha/alphaev5')
-rw-r--r--sysdeps/alpha/alphaev5/add_n.S146
-rw-r--r--sysdeps/alpha/alphaev5/lshift.S172
-rw-r--r--sysdeps/alpha/alphaev5/rshift.S170
-rw-r--r--sysdeps/alpha/alphaev5/sub_n.S147
4 files changed, 635 insertions, 0 deletions
diff --git a/sysdeps/alpha/alphaev5/add_n.S b/sysdeps/alpha/alphaev5/add_n.S
new file mode 100644
index 0000000000..09494c217f
--- /dev/null
+++ b/sysdeps/alpha/alphaev5/add_n.S
@@ -0,0 +1,146 @@
+ # Alpha __mpn_add_n -- Add two limb vectors of the same length > 0 and
+ # store sum in a third limb vector.
+
+ # Copyright (C) 1995-2014 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	$16
+ # s1_ptr	$17
+ # s2_ptr	$18
+ # size		$19
+
+	.set	noreorder
+	.set	noat
+.text
+	.align	3
+	.globl	__mpn_add_n
+	.ent	__mpn_add_n
+__mpn_add_n:
+	.frame	$30,0,$26,0
+
+	or	$31,$31,$25		# clear cy
+	subq	$19,4,$19		# decr loop cnt
+	blt	$19,.Lend2		# if less than 4 limbs, goto 2nd loop
+ # Start software pipeline for 1st loop
+	ldq	$0,0($18)
+	ldq	$1,8($18)
+	ldq	$4,0($17)
+	ldq	$5,8($17)
+	addq	$17,32,$17		# update s1_ptr
+	ldq	$2,16($18)
+	addq	$0,$4,$20		# 1st main add
+	ldq	$3,24($18)
+	subq	$19,4,$19		# decr loop cnt
+	ldq	$6,-16($17)
+	cmpult	$20,$0,$25		# compute cy from last add
+	ldq	$7,-8($17)
+	addq	$1,$25,$28		# cy add
+	addq	$18,32,$18		# update s2_ptr
+	addq	$5,$28,$21		# 2nd main add
+	cmpult	$28,$25,$8		# compute cy from last add
+	blt	$19,.Lend1		# if less than 4 limbs remain, jump
+ # 1st loop handles groups of 4 limbs in a software pipeline
+	.align	4
+.Loop:	cmpult	$21,$28,$25		# compute cy from last add
+	ldq	$0,0($18)
+	or	$8,$25,$25		# combine cy from the two adds
+	ldq	$1,8($18)
+	addq	$2,$25,$28		# cy add
+	ldq	$4,0($17)
+	addq	$28,$6,$22		# 3rd main add
+	ldq	$5,8($17)
+	cmpult	$28,$25,$8		# compute cy from last add
+	cmpult	$22,$28,$25		# compute cy from last add
+	stq	$20,0($16)
+	or	$8,$25,$25		# combine cy from the two adds
+	stq	$21,8($16)
+	addq	$3,$25,$28		# cy add
+	addq	$28,$7,$23		# 4th main add
+	cmpult	$28,$25,$8		# compute cy from last add
+	cmpult	$23,$28,$25		# compute cy from last add
+	addq	$17,32,$17		# update s1_ptr
+	or	$8,$25,$25		# combine cy from the two adds
+	addq	$16,32,$16		# update res_ptr
+	addq	$0,$25,$28		# cy add
+	ldq	$2,16($18)
+	addq	$4,$28,$20		# 1st main add
+	ldq	$3,24($18)
+	cmpult	$28,$25,$8		# compute cy from last add
+	ldq	$6,-16($17)
+	cmpult	$20,$28,$25		# compute cy from last add
+	ldq	$7,-8($17)
+	or	$8,$25,$25		# combine cy from the two adds
+	subq	$19,4,$19		# decr loop cnt
+	stq	$22,-16($16)
+	addq	$1,$25,$28		# cy add
+	stq	$23,-8($16)
+	addq	$5,$28,$21		# 2nd main add
+	addq	$18,32,$18		# update s2_ptr
+	cmpult	$28,$25,$8		# compute cy from last add
+	bge	$19,.Loop
+ # Finish software pipeline for 1st loop
+.Lend1:	cmpult	$21,$28,$25		# compute cy from last add
+	or	$8,$25,$25		# combine cy from the two adds
+	addq	$2,$25,$28		# cy add
+	addq	$28,$6,$22		# 3rd main add
+	cmpult	$28,$25,$8		# compute cy from last add
+	cmpult	$22,$28,$25		# compute cy from last add
+	stq	$20,0($16)
+	or	$8,$25,$25		# combine cy from the two adds
+	stq	$21,8($16)
+	addq	$3,$25,$28		# cy add
+	addq	$28,$7,$23		# 4th main add
+	cmpult	$28,$25,$8		# compute cy from last add
+	cmpult	$23,$28,$25		# compute cy from last add
+	or	$8,$25,$25		# combine cy from the two adds
+	addq	$16,32,$16		# update res_ptr
+	stq	$22,-16($16)
+	stq	$23,-8($16)
+.Lend2:	addq	$19,4,$19		# restore loop cnt
+	beq	$19,.Lret
+ # Start software pipeline for 2nd loop
+	ldq	$0,0($18)
+	ldq	$4,0($17)
+	subq	$19,1,$19
+	beq	$19,.Lend0
+ # 2nd loop handles remaining 1-3 limbs
+	.align	4
+.Loop0:	addq	$0,$25,$28		# cy add
+	ldq	$0,8($18)
+	addq	$4,$28,$20		# main add
+	ldq	$4,8($17)
+	addq	$18,8,$18
+	cmpult	$28,$25,$8		# compute cy from last add
+	addq	$17,8,$17
+	stq	$20,0($16)
+	cmpult	$20,$28,$25		# compute cy from last add
+	subq	$19,1,$19		# decr loop cnt
+	or	$8,$25,$25		# combine cy from the two adds
+	addq	$16,8,$16
+	bne	$19,.Loop0
+.Lend0:	addq	$0,$25,$28		# cy add
+	addq	$4,$28,$20		# main add
+	cmpult	$28,$25,$8		# compute cy from last add
+	cmpult	$20,$28,$25		# compute cy from last add
+	stq	$20,0($16)
+	or	$8,$25,$25		# combine cy from the two adds
+
+.Lret:	or	$25,$31,$0		# return cy
+	ret	$31,($26),1
+	.end	__mpn_add_n
diff --git a/sysdeps/alpha/alphaev5/lshift.S b/sysdeps/alpha/alphaev5/lshift.S
new file mode 100644
index 0000000000..459221f256
--- /dev/null
+++ b/sysdeps/alpha/alphaev5/lshift.S
@@ -0,0 +1,172 @@
+ # Alpha EV5 __mpn_lshift --
+
+ # Copyright (C) 1994-2014 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 3.25 cycles/limb on the EV5.
+
+	.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	$31,$19,$20
+	s8addq	$18,$16,$16	# make r16 point at end of RES
+	subq	$18,1,$18
+	and	$18,4-1,$28	# number of limbs in first loop
+	srl	$4,$20,$0	# compute function result
+
+	beq	$28,.L0
+	subq	$18,$28,$18
+
+	.align	3
+.Loop0:	ldq	$3,-16($17)
+	subq	$16,8,$16
+	sll	$4,$19,$5
+	subq	$17,8,$17
+	subq	$28,1,$28
+	srl	$3,$20,$6
+	or	$3,$3,$4
+	or	$5,$6,$8
+	stq	$8,0($16)
+	bne	$28,.Loop0
+
+.L0:	sll	$4,$19,$24
+	beq	$18,.Lend
+ # warm up phase 1
+	ldq	$1,-16($17)
+	subq	$18,4,$18
+	ldq	$2,-24($17)
+	ldq	$3,-32($17)
+	ldq	$4,-40($17)
+	beq	$18,.Lend1
+ # warm up phase 2
+	srl	$1,$20,$7
+	sll	$1,$19,$21
+	srl	$2,$20,$8
+	ldq	$1,-48($17)
+	sll	$2,$19,$22
+	ldq	$2,-56($17)
+	srl	$3,$20,$5
+	or	$7,$24,$7
+	sll	$3,$19,$23
+	or	$8,$21,$8
+	srl	$4,$20,$6
+	ldq	$3,-64($17)
+	sll	$4,$19,$24
+	ldq	$4,-72($17)
+	subq	$18,4,$18
+	beq	$18,.Lend2
+	.align  4
+ # main loop
+.Loop:	stq	$7,-8($16)
+	or	$5,$22,$5
+	stq	$8,-16($16)
+	or	$6,$23,$6
+
+	srl	$1,$20,$7
+	subq	$18,4,$18
+	sll	$1,$19,$21
+	unop	# ldq	$31,-96($17)
+
+	srl	$2,$20,$8
+	ldq	$1,-80($17)
+	sll	$2,$19,$22
+	ldq	$2,-88($17)
+
+	stq	$5,-24($16)
+	or	$7,$24,$7
+	stq	$6,-32($16)
+	or	$8,$21,$8
+
+	srl	$3,$20,$5
+	unop	# ldq	$31,-96($17)
+	sll	$3,$19,$23
+	subq	$16,32,$16
+
+	srl	$4,$20,$6
+	ldq	$3,-96($17)
+	sll	$4,$19,$24
+	ldq	$4,-104($17)
+
+	subq	$17,32,$17
+	bne	$18,.Loop
+ # cool down phase 2/1
+.Lend2:	stq	$7,-8($16)
+	or	$5,$22,$5
+	stq	$8,-16($16)
+	or	$6,$23,$6
+	srl	$1,$20,$7
+	sll	$1,$19,$21
+	srl	$2,$20,$8
+	sll	$2,$19,$22
+	stq	$5,-24($16)
+	or	$7,$24,$7
+	stq	$6,-32($16)
+	or	$8,$21,$8
+	srl	$3,$20,$5
+	sll	$3,$19,$23
+	srl	$4,$20,$6
+	sll	$4,$19,$24
+ # cool down phase 2/2
+	stq	$7,-40($16)
+	or	$5,$22,$5
+	stq	$8,-48($16)
+	or	$6,$23,$6
+	stq	$5,-56($16)
+	stq	$6,-64($16)
+ # cool down phase 2/3
+	stq	$24,-72($16)
+	ret	$31,($26),1
+
+ # cool down phase 1/1
+.Lend1:	srl	$1,$20,$7
+	sll	$1,$19,$21
+	srl	$2,$20,$8
+	sll	$2,$19,$22
+	srl	$3,$20,$5
+	or	$7,$24,$7
+	sll	$3,$19,$23
+	or	$8,$21,$8
+	srl	$4,$20,$6
+	sll	$4,$19,$24
+ # cool down phase 1/2
+	stq	$7,-8($16)
+	or	$5,$22,$5
+	stq	$8,-16($16)
+	or	$6,$23,$6
+	stq	$5,-24($16)
+	stq	$6,-32($16)
+	stq	$24,-40($16)
+	ret	$31,($26),1
+
+.Lend:	stq	$24,-8($16)
+	ret	$31,($26),1
+	.end	__mpn_lshift
diff --git a/sysdeps/alpha/alphaev5/rshift.S b/sysdeps/alpha/alphaev5/rshift.S
new file mode 100644
index 0000000000..0c53022c9d
--- /dev/null
+++ b/sysdeps/alpha/alphaev5/rshift.S
@@ -0,0 +1,170 @@
+ # Alpha EV5 __mpn_rshift --
+
+ # Copyright (C) 1994-2014 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 3.25 cycles/limb on the EV5.
+
+	.set	noreorder
+	.set	noat
+.text
+	.align	3
+	.globl	__mpn_rshift
+	.ent	__mpn_rshift
+__mpn_rshift:
+	.frame	$30,0,$26,0
+
+	ldq	$4,0($17)	# load first limb
+	subq	$31,$19,$20
+	subq	$18,1,$18
+	and	$18,4-1,$28	# number of limbs in first loop
+	sll	$4,$20,$0	# compute function result
+
+	beq	$28,.L0
+	subq	$18,$28,$18
+
+	.align	3
+.Loop0:	ldq	$3,8($17)
+	addq	$16,8,$16
+	srl	$4,$19,$5
+	addq	$17,8,$17
+	subq	$28,1,$28
+	sll	$3,$20,$6
+	or	$3,$3,$4
+	or	$5,$6,$8
+	stq	$8,-8($16)
+	bne	$28,.Loop0
+
+.L0:	srl	$4,$19,$24
+	beq	$18,.Lend
+ # warm up phase 1
+	ldq	$1,8($17)
+	subq	$18,4,$18
+	ldq	$2,16($17)
+	ldq	$3,24($17)
+	ldq	$4,32($17)
+	beq	$18,.Lend1
+ # warm up phase 2
+	sll	$1,$20,$7
+	srl	$1,$19,$21
+	sll	$2,$20,$8
+	ldq	$1,40($17)
+	srl	$2,$19,$22
+	ldq	$2,48($17)
+	sll	$3,$20,$5
+	or	$7,$24,$7
+	srl	$3,$19,$23
+	or	$8,$21,$8
+	sll	$4,$20,$6
+	ldq	$3,56($17)
+	srl	$4,$19,$24
+	ldq	$4,64($17)
+	subq	$18,4,$18
+	beq	$18,.Lend2
+	.align  4
+ # main loop
+.Loop:	stq	$7,0($16)
+	or	$5,$22,$5
+	stq	$8,8($16)
+	or	$6,$23,$6
+
+	sll	$1,$20,$7
+	subq	$18,4,$18
+	srl	$1,$19,$21
+	unop	# ldq	$31,-96($17)
+
+	sll	$2,$20,$8
+	ldq	$1,72($17)
+	srl	$2,$19,$22
+	ldq	$2,80($17)
+
+	stq	$5,16($16)
+	or	$7,$24,$7
+	stq	$6,24($16)
+	or	$8,$21,$8
+
+	sll	$3,$20,$5
+	unop	# ldq	$31,-96($17)
+	srl	$3,$19,$23
+	addq	$16,32,$16
+
+	sll	$4,$20,$6
+	ldq	$3,88($17)
+	srl	$4,$19,$24
+	ldq	$4,96($17)
+
+	addq	$17,32,$17
+	bne	$18,.Loop
+ # cool down phase 2/1
+.Lend2:	stq	$7,0($16)
+	or	$5,$22,$5
+	stq	$8,8($16)
+	or	$6,$23,$6
+	sll	$1,$20,$7
+	srl	$1,$19,$21
+	sll	$2,$20,$8
+	srl	$2,$19,$22
+	stq	$5,16($16)
+	or	$7,$24,$7
+	stq	$6,24($16)
+	or	$8,$21,$8
+	sll	$3,$20,$5
+	srl	$3,$19,$23
+	sll	$4,$20,$6
+	srl	$4,$19,$24
+ # cool down phase 2/2
+	stq	$7,32($16)
+	or	$5,$22,$5
+	stq	$8,40($16)
+	or	$6,$23,$6
+	stq	$5,48($16)
+	stq	$6,56($16)
+ # cool down phase 2/3
+	stq	$24,64($16)
+	ret	$31,($26),1
+
+ # cool down phase 1/1
+.Lend1:	sll	$1,$20,$7
+	srl	$1,$19,$21
+	sll	$2,$20,$8
+	srl	$2,$19,$22
+	sll	$3,$20,$5
+	or	$7,$24,$7
+	srl	$3,$19,$23
+	or	$8,$21,$8
+	sll	$4,$20,$6
+	srl	$4,$19,$24
+ # cool down phase 1/2
+	stq	$7,0($16)
+	or	$5,$22,$5
+	stq	$8,8($16)
+	or	$6,$23,$6
+	stq	$5,16($16)
+	stq	$6,24($16)
+	stq	$24,32($16)
+	ret	$31,($26),1
+
+.Lend:	stq	$24,0($16)
+	ret	$31,($26),1
+	.end	__mpn_rshift
diff --git a/sysdeps/alpha/alphaev5/sub_n.S b/sysdeps/alpha/alphaev5/sub_n.S
new file mode 100644
index 0000000000..4a53e92c88
--- /dev/null
+++ b/sysdeps/alpha/alphaev5/sub_n.S
@@ -0,0 +1,147 @@
+ # Alpha __mpn_sub_n -- Subtract two limb vectors of the same length > 0 and
+ # store difference in a third limb vector.
+
+ # Copyright (C) 1995-2014 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	$16
+ # s1_ptr	$17
+ # s2_ptr	$18
+ # size		$19
+
+	.set	noreorder
+	.set	noat
+.text
+	.align	3
+	.globl	__mpn_sub_n
+	.ent	__mpn_sub_n
+__mpn_sub_n:
+	.frame	$30,0,$26,0
+
+	or	$31,$31,$25		# clear cy
+	subq	$19,4,$19		# decr loop cnt
+	blt	$19,.Lend2		# if less than 4 limbs, goto 2nd loop
+ # Start software pipeline for 1st loop
+	ldq	$0,0($18)
+	ldq	$1,8($18)
+	ldq	$4,0($17)
+	ldq	$5,8($17)
+	addq	$17,32,$17		# update s1_ptr
+	ldq	$2,16($18)
+	subq	$4,$0,$20		# 1st main sub
+	ldq	$3,24($18)
+	subq	$19,4,$19		# decr loop cnt
+	ldq	$6,-16($17)
+	cmpult	$4,$20,$25		# compute cy from last sub
+	ldq	$7,-8($17)
+	addq	$1,$25,$28		# cy add
+	addq	$18,32,$18		# update s2_ptr
+	subq	$5,$28,$21		# 2nd main sub
+	cmpult	$28,$25,$8		# compute cy from last add
+	blt	$19,.Lend1		# if less than 4 limbs remain, jump
+ # 1st loop handles groups of 4 limbs in a software pipeline
+	.align	4
+.Loop:	cmpult	$5,$21,$25		# compute cy from last add
+	ldq	$0,0($18)
+	or	$8,$25,$25		# combine cy from the two adds
+	ldq	$1,8($18)
+	addq	$2,$25,$28		# cy add
+	ldq	$4,0($17)
+	subq	$6,$28,$22		# 3rd main sub
+	ldq	$5,8($17)
+	cmpult	$28,$25,$8		# compute cy from last add
+	cmpult	$6,$22,$25		# compute cy from last add
+	stq	$20,0($16)
+	or	$8,$25,$25		# combine cy from the two adds
+	stq	$21,8($16)
+	addq	$3,$25,$28		# cy add
+	subq	$7,$28,$23		# 4th main sub
+	cmpult	$28,$25,$8		# compute cy from last add
+	cmpult	$7,$23,$25		# compute cy from last add
+	addq	$17,32,$17		# update s1_ptr
+	or	$8,$25,$25		# combine cy from the two adds
+	addq	$16,32,$16		# update res_ptr
+	addq	$0,$25,$28		# cy add
+	ldq	$2,16($18)
+	subq	$4,$28,$20		# 1st main sub
+	ldq	$3,24($18)
+	cmpult	$28,$25,$8		# compute cy from last add
+	ldq	$6,-16($17)
+	cmpult	$4,$20,$25		# compute cy from last add
+	ldq	$7,-8($17)
+	or	$8,$25,$25		# combine cy from the two adds
+	subq	$19,4,$19		# decr loop cnt
+	stq	$22,-16($16)
+	addq	$1,$25,$28		# cy add
+	stq	$23,-8($16)
+	subq	$5,$28,$21		# 2nd main sub
+	addq	$18,32,$18		# update s2_ptr
+	cmpult	$28,$25,$8		# compute cy from last add
+	bge	$19,.Loop
+ # Finish software pipeline for 1st loop
+.Lend1:	cmpult	$5,$21,$25		# compute cy from last add
+	or	$8,$25,$25		# combine cy from the two adds
+	addq	$2,$25,$28		# cy add
+	subq	$6,$28,$22		# 3rd main sub
+	cmpult	$28,$25,$8		# compute cy from last add
+	cmpult	$6,$22,$25		# compute cy from last add
+	stq	$20,0($16)
+	or	$8,$25,$25		# combine cy from the two adds
+	stq	$21,8($16)
+	addq	$3,$25,$28		# cy add
+	subq	$7,$28,$23		# 4th main sub
+	cmpult	$28,$25,$8		# compute cy from last add
+	cmpult	$7,$23,$25		# compute cy from last add
+	or	$8,$25,$25		# combine cy from the two adds
+	addq	$16,32,$16		# update res_ptr
+	stq	$22,-16($16)
+	stq	$23,-8($16)
+.Lend2:	addq	$19,4,$19		# restore loop cnt
+	beq	$19,.Lret
+ # Start software pipeline for 2nd loop
+	ldq	$0,0($18)
+	ldq	$4,0($17)
+	subq	$19,1,$19
+	beq	$19,.Lend0
+ # 2nd loop handles remaining 1-3 limbs
+	.align	4
+.Loop0:	addq	$0,$25,$28		# cy add
+	ldq	$0,8($18)
+	subq	$4,$28,$20		# main sub
+	ldq	$1,8($17)
+	addq	$18,8,$18
+	cmpult	$28,$25,$8		# compute cy from last add
+	addq	$17,8,$17
+	stq	$20,0($16)
+	cmpult	$4,$20,$25		# compute cy from last add
+	subq	$19,1,$19		# decr loop cnt
+	or	$8,$25,$25		# combine cy from the two adds
+	addq	$16,8,$16
+	or	$1,$31,$4
+	bne	$19,.Loop0
+.Lend0:	addq	$0,$25,$28		# cy add
+	subq	$4,$28,$20		# main sub
+	cmpult	$28,$25,$8		# compute cy from last add
+	cmpult	$4,$20,$25		# compute cy from last add
+	stq	$20,0($16)
+	or	$8,$25,$25		# combine cy from the two adds
+
+.Lret:	or	$25,$31,$0		# return cy
+	ret	$31,($26),1
+	.end	__mpn_sub_n