[thirdparty/glibc.git] / sysdeps / alpha / memset.S

/* Copyright (C) 1996-2015 Free Software Foundation, Inc.
   Contributed by Richard Henderson (rth@tamu.edu)
   This file is part of the GNU C Library.

   The GNU C 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 C 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 C Library.  If not, see
   <http://www.gnu.org/licenses/>.  */

/* Fill a block of memory with a character.  Optimized for the Alpha
   architecture:

   - memory accessed as aligned quadwords only
   - destination memory not read unless needed for good cache behaviour
   - basic blocks arranged to optimize branch prediction for full-quadword
     aligned memory blocks.
   - partial head and tail quadwords constructed with byte-mask instructions

   This is generally scheduled for the EV5 (got to look out for my own
   interests :-), but with EV4 needs in mind.  There *should* be no more
   stalls for the EV4 than there are for the EV5.
*/


#include <sysdep.h>

	.set noat
	.set noreorder

	.text
	.type	memset, @function
	.globl	memset
	.usepv	memset, USEPV_PROF

	cfi_startproc

	/* On entry to this basic block:
	   t3 == loop counter
	   t4 == bytes in partial final word
	   a0 == possibly misaligned destination pointer
	   a1 == replicated source character  */

	.align 3
memset_loop:
	beq	t3, $tail
	blbc	t3, 0f		# skip single store if count even

	stq_u	a1, 0(a0)	# e0    : store one word
	subq	t3, 1, t3	# .. e1 :
	addq	a0, 8, a0	# e0    :
	beq	t3, $tail	# .. e1 :

0:	stq_u	a1, 0(a0)	# e0    : store two words
	subq	t3, 2, t3	# .. e1 :
	stq_u	a1, 8(a0)	# e0    :
	addq	a0, 16, a0	# .. e1 :
	bne	t3, 0b		# e1    :

$tail:	bne	t4, 1f		# is there a tail to do?
	ret			# no

	.align 3
1:	ldq_u	t0, 0(a0)	# e1    : yes, load original data
	mskql	a1, t4, t1	# .. e0 :
	mskqh	t0, t4, t0	# e0    :
	or	t0, t1, t0	# e1 (stall)
	stq_u	t0, 0(a0)	# e0    :
	ret			# .. e1 :

memset:
#ifdef PROF
	ldgp	gp, 0(pv)
	lda	AT, _mcount
	jsr	AT, (AT), _mcount
#endif

	and	a1, 0xff, a1	# e0    : zero extend input character
	mov	a0, v0		# .. e1 : move return value in place
	sll	a1, 8, t0	# e0    : begin replicating the char
	beq	a2, $done	# .. e1 : early exit for zero-length store
	or	t0, a1, a1	# e0    :
	and	a0, 7, t1	# .. e1 : dest misalignment
	sll	a1, 16, t0	# e0    :
	addq	a2, t1, a2	# .. e1 : add dest misalignment to count
	or	t0, a1, a1	# e0    :
	srl	a2, 3, t3	# .. e1 : loop = count >> 3
	sll	a1, 32, t0	# e0    :
	and	a2, 7, t4	# .. e1 : find number of bytes in tail
	or	t0, a1, a1	# e0    : character replication done

	beq	t1, memset_loop	# .. e1 : aligned head, jump right in

	ldq_u	t0, 0(a0)	# e1    : load original data to mask into
	mskqh	a1, a0, t1	# .. e0 :

	cmpult	a2, 8, t2	# e0    : is this a sub-word set?
	bne	t2, $oneq	# .. e1 (zdb)

	mskql	t0, a0, t0	# e0    : we span words.  finish this partial
	subq	t3, 1, t3	# .. e1 :
	addq	a0, 8, a0	# e0    :
	or	t0, t1, t0	# .. e1 :
	stq_u	t0, -8(a0)	# e0    :
	br 	memset_loop	# .. e1 :

	.align 3
$oneq:
	mskql	t1, a2, t1	# e0    : entire operation within one word
	mskql	t0, a0, t2	# e0    :
	mskqh	t0, a2, t3	# e0    :
	or	t1, t2, t0	# .. e1 :
	or	t0, t3, t0	# e1    :
	stq_u	t0, 0(a0)	# e0 (stall)

$done:	ret

	cfi_endproc
libc_hidden_builtin_def (memset)
Commit	Line	Data
b168057a	1	/* Copyright (C) 1996-2015 Free Software Foundation, Inc.
cf182b58	2	Contributed by Richard Henderson (rth@tamu.edu)
db31c863	3	This file is part of the GNU C Library.
cf182b58	4
db31c863	5	The GNU C Library is free software; you can redistribute it and/or
3214b89b AJ	6	modify it under the terms of the GNU Lesser General Public
	7	License as published by the Free Software Foundation; either
	8	version 2.1 of the License, or (at your option) any later version.
cf182b58	9
db31c863 UD	10	The GNU C Library is distributed in the hope that it will be useful,
	11	but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
3214b89b	13	Lesser General Public License for more details.
cf182b58	14
3214b89b	15	You should have received a copy of the GNU Lesser General Public
ab84e3ff PE	16	License along with the GNU C Library. If not, see
ab84e3ff PE	17	<http://www.gnu.org/licenses/>. */
cf182b58 UD	18
	19	/* Fill a block of memory with a character. Optimized for the Alpha
	20	architecture:
	21
	22	- memory accessed as aligned quadwords only
	23	- destination memory not read unless needed for good cache behaviour
	24	- basic blocks arranged to optimize branch prediction for full-quadword
	25	aligned memory blocks.
	26	- partial head and tail quadwords constructed with byte-mask instructions
	27
	28	This is generally scheduled for the EV5 (got to look out for my own
	29	interests :-), but with EV4 needs in mind. There should be no more
	30	stalls for the EV4 than there are for the EV5.
	31	*/
	32
	33
	34	#include <sysdep.h>
	35
	36	.set noat
	37	.set noreorder
	38
	39	.text
b2afe910 RH	40	.type memset, @function
	41	.globl memset
	42	.usepv memset, USEPV_PROF
cf182b58	43
b2afe910	44	cfi_startproc
cf182b58 UD	45
	46	/* On entry to this basic block:
	47	t3 == loop counter
	48	t4 == bytes in partial final word
	49	a0 == possibly misaligned destination pointer
	50	a1 == replicated source character */
	51
cf182b58 UD	52	.align 3
cf182b58 UD	53	memset_loop:
cf182b58 UD	54	beq t3, $tail
	55	blbc t3, 0f # skip single store if count even
	56
	57	stq_u a1, 0(a0) # e0 : store one word
	58	subq t3, 1, t3 # .. e1 :
	59	addq a0, 8, a0 # e0 :
	60	beq t3, $tail # .. e1 :
	61
	62	0: stq_u a1, 0(a0) # e0 : store two words
	63	subq t3, 2, t3 # .. e1 :
	64	stq_u a1, 8(a0) # e0 :
	65	addq a0, 16, a0 # .. e1 :
	66	bne t3, 0b # e1 :
	67
	68	$tail: bne t4, 1f # is there a tail to do?
	69	ret # no
	70
	71	.align 3
	72	1: ldq_u t0, 0(a0) # e1 : yes, load original data
	73	mskql a1, t4, t1 # .. e0 :
	74	mskqh t0, t4, t0 # e0 :
	75	or t0, t1, t0 # e1 (stall)
	76	stq_u t0, 0(a0) # e0 :
	77	ret # .. e1 :
	78
b2afe910	79	memset:
60c74cf0 UD	80	#ifdef PROF
	81	ldgp gp, 0(pv)
	82	lda AT, _mcount
	83	jsr AT, (AT), _mcount
60c74cf0	84	#endif
cf182b58	85
b2afe910	86	and a1, 0xff, a1 # e0 : zero extend input character
cf182b58 UD	87	mov a0, v0 # .. e1 : move return value in place
	88	sll a1, 8, t0 # e0 : begin replicating the char
	89	beq a2, $done # .. e1 : early exit for zero-length store
	90	or t0, a1, a1 # e0 :
	91	and a0, 7, t1 # .. e1 : dest misalignment
	92	sll a1, 16, t0 # e0 :
	93	addq a2, t1, a2 # .. e1 : add dest misalignment to count
	94	or t0, a1, a1 # e0 :
	95	srl a2, 3, t3 # .. e1 : loop = count >> 3
	96	sll a1, 32, t0 # e0 :
	97	and a2, 7, t4 # .. e1 : find number of bytes in tail
	98	or t0, a1, a1 # e0 : character replication done
	99
	100	beq t1, memset_loop # .. e1 : aligned head, jump right in
	101
	102	ldq_u t0, 0(a0) # e1 : load original data to mask into
	103	mskqh a1, a0, t1 # .. e0 :
	104
	105	cmpult a2, 8, t2 # e0 : is this a sub-word set?
	106	bne t2, $oneq # .. e1 (zdb)
	107
	108	mskql t0, a0, t0 # e0 : we span words. finish this partial
	109	subq t3, 1, t3 # .. e1 :
	110	addq a0, 8, a0 # e0 :
	111	or t0, t1, t0 # .. e1 :
	112	stq_u t0, -8(a0) # e0 :
	113	br memset_loop # .. e1 :
	114
	115	.align 3
	116	$oneq:
	117	mskql t1, a2, t1 # e0 : entire operation within one word
	118	mskql t0, a0, t2 # e0 :
	119	mskqh t0, a2, t3 # e0 :
	120	or t1, t2, t0 # .. e1 :
	121	or t0, t3, t0 # e1 :
	122	stq_u t0, 0(a0) # e0 (stall)
	123
	124	$done: ret
	125
b2afe910	126	cfi_endproc
79b7c863	127	libc_hidden_builtin_def (memset)