[thirdparty/glibc.git] / sysdeps / powerpc / powerpc64 / power7 / strchr.S

/* Optimized strchr implementation for PowerPC64/POWER7 using cmpb insn.
   Copyright (C) 2010-2023 Free Software Foundation, Inc.
   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
   <https://www.gnu.org/licenses/>.  */

#include <sysdep.h>

#ifndef STRCHR
# define STRCHR strchr
#endif

/* int [r3] strchr (char *s [r3], int c [r4])  */
	.machine  power7
ENTRY_TOCLESS (STRCHR)
	CALL_MCOUNT 2
	dcbt	0,r3
	clrrdi	r8,r3,3	      /* Align the address to doubleword boundary.  */
	cmpdi	cr7,r4,0
	ld	r12,0(r8)     /* Load doubleword from memory.  */
	li	r0,0	      /* Doubleword with null chars to use
				 with cmpb.  */

	rlwinm	r6,r3,3,26,28 /* Calculate padding.  */

	beq	cr7,L(null_match)

	/* Replicate byte to doubleword.  */
	insrdi	r4,r4,8,48
	insrdi	r4,r4,16,32
	insrdi  r4,r4,32,0

	/* Now r4 has a doubleword of c bytes and r0 has
	   a doubleword of null bytes.  */

	cmpb	r10,r12,r4     /* Compare each byte against c byte.  */
	cmpb	r11,r12,r0     /* Compare each byte against null byte.  */

	/* Move the doublewords left and right to discard the bits that are
	   not part of the string and bring them back as zeros.  */
#ifdef __LITTLE_ENDIAN__
	srd	r10,r10,r6
	srd	r11,r11,r6
	sld	r10,r10,r6
	sld	r11,r11,r6
#else
	sld	r10,r10,r6
	sld	r11,r11,r6
	srd	r10,r10,r6
	srd	r11,r11,r6
#endif
	or	r5,r10,r11    /* OR the results to speed things up.  */
	cmpdi	cr7,r5,0      /* If r5 == 0, no c or null bytes
				 have been found.  */
	bne	cr7,L(done)

	mtcrf   0x01,r8

	/* Are we now aligned to a doubleword boundary?  If so, skip to
	   the main loop.  Otherwise, go through the alignment code.  */

	bt	28,L(loop)

	/* Handle WORD2 of pair.  */
	ldu	r12,8(r8)
	cmpb    r10,r12,r4
	cmpb	r11,r12,r0
	or	r5,r10,r11
	cmpdi	cr7,r5,0
	bne	cr7,L(done)
	b	L(loop)	      /* We branch here (rather than falling through)
				 to skip the nops due to heavy alignment
				 of the loop below.  */

	.p2align  5
L(loop):
	/* Load two doublewords, compare and merge in a
	   single register for speed.  This is an attempt
	   to speed up the null-checking process for bigger strings.  */
	ld	r12,8(r8)
	ldu	r9,16(r8)
	cmpb	r10,r12,r4
	cmpb	r11,r12,r0
	cmpb	r6,r9,r4
	cmpb	r7,r9,r0
	or	r12,r10,r11
	or	r9,r6,r7
	or	r5,r12,r9
	cmpdi	cr7,r5,0
	beq	cr7,L(loop)

	/* OK, one (or both) of the doublewords contains a c/null byte.  Check
	   the first doubleword and decrement the address in case the first
	   doubleword really contains a c/null byte.  */

	cmpdi	cr6,r12,0
	addi	r8,r8,-8
	bne	cr6,L(done)

	/* The c/null byte must be in the second doubleword.  Adjust the
	   address again and move the result of cmpb to r10 so we can calculate
	   the pointer.  */

	mr	r10,r6
	mr	r11,r7
	addi	r8,r8,8

	/* r10/r11 have the output of the cmpb instructions, that is,
	   0xff in the same position as the c/null byte in the original
	   doubleword from the string.  Use that to calculate the pointer.  */
L(done):
#ifdef __LITTLE_ENDIAN__
	addi    r3,r10,-1
	andc    r3,r3,r10
	popcntd	r0,r3
	addi    r4,r11,-1
	andc    r4,r4,r11
	cmpld	cr7,r3,r4
	bgt	cr7,L(no_match)
#else
	cntlzd	r0,r10	      /* Count leading zeros before c matches.  */
	cmpld	cr7,r11,r10
	bgt	cr7,L(no_match)
#endif
	srdi	r0,r0,3	      /* Convert leading zeros to bytes.  */
	add	r3,r8,r0      /* Return address of the matching c byte
				 or null in case c was not found.  */
	blr

	.align	4
L(no_match):
	li	r3,0
	blr

/* We are here because strchr was called with a null byte.  */
	.align	4
L(null_match):
	/* r0 has a doubleword of null bytes.  */

	cmpb	r5,r12,r0     /* Compare each byte against null bytes.  */

	/* Move the doublewords left and right to discard the bits that are
	   not part of the string and bring them back as zeros.  */
#ifdef __LITTLE_ENDIAN__
	srd	r5,r5,r6
	sld	r5,r5,r6
#else
	sld	r5,r5,r6
	srd	r5,r5,r6
#endif
	cmpdi	cr7,r5,0      /* If r10 == 0, no c or null bytes
				 have been found.  */
	bne	cr7,L(done_null)

	mtcrf   0x01,r8

	/* Are we now aligned to a quadword boundary?  If so, skip to
	   the main loop.  Otherwise, go through the alignment code.  */

	bt	28,L(loop_null)

	/* Handle WORD2 of pair.  */
	ldu	r12,8(r8)
	cmpb    r5,r12,r0
	cmpdi	cr7,r5,0
	bne	cr7,L(done_null)
	b	L(loop_null)  /* We branch here (rather than falling through)
				 to skip the nops due to heavy alignment
				 of the loop below.  */

	/* Main loop to look for the end of the string.  Since it's a
	   small loop (< 8 instructions), align it to 32-bytes.  */
	.p2align  5
L(loop_null):
	/* Load two doublewords, compare and merge in a
	   single register for speed.  This is an attempt
	   to speed up the null-checking process for bigger strings.  */
	ld	r12,8(r8)
	ldu     r11,16(r8)
	cmpb	r5,r12,r0
	cmpb	r10,r11,r0
	or	r6,r5,r10
	cmpdi	cr7,r6,0
	beq	cr7,L(loop_null)

	/* OK, one (or both) of the doublewords contains a null byte.  Check
	   the first doubleword and decrement the address in case the first
	   doubleword really contains a null byte.  */

	cmpdi	cr6,r5,0
	addi	r8,r8,-8
	bne	cr6,L(done_null)

	/* The null byte must be in the second doubleword.  Adjust the address
	   again and move the result of cmpb to r10 so we can calculate the
	   pointer.  */

	mr	r5,r10
	addi	r8,r8,8

	/* r5 has the output of the cmpb instruction, that is, it contains
	   0xff in the same position as the null byte in the original
	   doubleword from the string.  Use that to calculate the pointer.  */
L(done_null):
#ifdef __LITTLE_ENDIAN__
	addi    r0,r5,-1
	andc    r0,r0,r5
	popcntd	r0,r0
#else
	cntlzd	r0,r5	      /* Count leading zeros before the match.  */
#endif
	srdi	r0,r0,3	      /* Convert leading zeros to bytes.  */
	add	r3,r8,r0      /* Return address of the matching null byte.  */
	blr
END (STRCHR)
weak_alias (strchr, index)
libc_hidden_builtin_def (strchr)
Commit	Line	Data
fe2f79db	1	/* Optimized strchr implementation for PowerPC64/POWER7 using cmpb insn.
6d7e8eda	2	Copyright (C) 2010-2023 Free Software Foundation, Inc.
fe2f79db LM	3	This file is part of the GNU C Library.
	4
	5	The GNU C Library is free software; you can redistribute it and/or
	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.
	9
	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
	13	Lesser General Public License for more details.
	14
	15	You should have received a copy of the GNU Lesser General Public
59ba27a6	16	License along with the GNU C Library; if not, see
5a82c748	17	<https://www.gnu.org/licenses/>. */
fe2f79db LM	18
fe2f79db LM	19	#include <sysdep.h>
fe2f79db	20
6d15a5c2 WSM	21	#ifndef STRCHR
	22	# define STRCHR strchr
	23	#endif
	24
fe2f79db LM	25	/* int [r3] strchr (char s [r3], int c [r4]) /
fe2f79db LM	26	.machine power7
d5b41185	27	ENTRY_TOCLESS (STRCHR)
fe2f79db LM	28	CALL_MCOUNT 2
	29	dcbt 0,r3
	30	clrrdi r8,r3,3 /* Align the address to doubleword boundary. */
	31	cmpdi cr7,r4,0
	32	ld r12,0(r8) /* Load doubleword from memory. */
	33	li r0,0 /* Doubleword with null chars to use
	34	with cmpb. */
	35
	36	rlwinm r6,r3,3,26,28 /* Calculate padding. */
	37
	38	beq cr7,L(null_match)
	39
	40	/* Replicate byte to doubleword. */
664318c3 AM	41	insrdi r4,r4,8,48
664318c3 AM	42	insrdi r4,r4,16,32
fe2f79db LM	43	insrdi r4,r4,32,0
	44
	45	/* Now r4 has a doubleword of c bytes and r0 has
	46	a doubleword of null bytes. */
	47
	48	cmpb r10,r12,r4 /* Compare each byte against c byte. */
	49	cmpb r11,r12,r0 /* Compare each byte against null byte. */
	50
	51	/* Move the doublewords left and right to discard the bits that are
	52	not part of the string and bring them back as zeros. */
664318c3 AM	53	#ifdef __LITTLE_ENDIAN__
	54	srd r10,r10,r6
	55	srd r11,r11,r6
	56	sld r10,r10,r6
	57	sld r11,r11,r6
	58	#else
fe2f79db LM	59	sld r10,r10,r6
	60	sld r11,r11,r6
	61	srd r10,r10,r6
	62	srd r11,r11,r6
664318c3	63	#endif
fe2f79db LM	64	or r5,r10,r11 /* OR the results to speed things up. */
	65	cmpdi cr7,r5,0 /* If r5 == 0, no c or null bytes
	66	have been found. */
	67	bne cr7,L(done)
	68
	69	mtcrf 0x01,r8
	70
	71	/* Are we now aligned to a doubleword boundary? If so, skip to
	72	the main loop. Otherwise, go through the alignment code. */
	73
	74	bt 28,L(loop)
	75
	76	/* Handle WORD2 of pair. */
	77	ldu r12,8(r8)
	78	cmpb r10,r12,r4
	79	cmpb r11,r12,r0
	80	or r5,r10,r11
	81	cmpdi cr7,r5,0
	82	bne cr7,L(done)
	83	b L(loop) /* We branch here (rather than falling through)
	84	to skip the nops due to heavy alignment
	85	of the loop below. */
	86
	87	.p2align 5
	88	L(loop):
	89	/* Load two doublewords, compare and merge in a
	90	single register for speed. This is an attempt
	91	to speed up the null-checking process for bigger strings. */
	92	ld r12,8(r8)
	93	ldu r9,16(r8)
	94	cmpb r10,r12,r4
	95	cmpb r11,r12,r0
	96	cmpb r6,r9,r4
	97	cmpb r7,r9,r0
	98	or r12,r10,r11
	99	or r9,r6,r7
	100	or r5,r12,r9
	101	cmpdi cr7,r5,0
	102	beq cr7,L(loop)
	103
	104	/* OK, one (or both) of the doublewords contains a c/null byte. Check
	105	the first doubleword and decrement the address in case the first
	106	doubleword really contains a c/null byte. */
	107
	108	cmpdi cr6,r12,0
	109	addi r8,r8,-8
	110	bne cr6,L(done)
	111
	112	/* The c/null byte must be in the second doubleword. Adjust the
	113	address again and move the result of cmpb to r10 so we can calculate
	114	the pointer. */
	115
	116	mr r10,r6
	117	mr r11,r7
	118	addi r8,r8,8
	119
664318c3	120	/* r10/r11 have the output of the cmpb instructions, that is,
fe2f79db LM	121	0xff in the same position as the c/null byte in the original
	122	doubleword from the string. Use that to calculate the pointer. */
	123	L(done):
664318c3 AM	124	#ifdef __LITTLE_ENDIAN__
	125	addi r3,r10,-1
	126	andc r3,r3,r10
	127	popcntd r0,r3
	128	addi r4,r11,-1
	129	andc r4,r4,r11
	130	cmpld cr7,r3,r4
fe2f79db	131	bgt cr7,L(no_match)
664318c3 AM	132	#else
	133	cntlzd r0,r10 /* Count leading zeros before c matches. */
	134	cmpld cr7,r11,r10
	135	bgt cr7,L(no_match)
	136	#endif
	137	srdi r0,r0,3 /* Convert leading zeros to bytes. */
fe2f79db LM	138	add r3,r8,r0 /* Return address of the matching c byte
	139	or null in case c was not found. */
	140	blr
	141
	142	.align 4
	143	L(no_match):
	144	li r3,0
	145	blr
	146
	147	/* We are here because strchr was called with a null byte. */
	148	.align 4
	149	L(null_match):
	150	/* r0 has a doubleword of null bytes. */
	151
	152	cmpb r5,r12,r0 /* Compare each byte against null bytes. */
	153
	154	/* Move the doublewords left and right to discard the bits that are
	155	not part of the string and bring them back as zeros. */
664318c3 AM	156	#ifdef __LITTLE_ENDIAN__
	157	srd r5,r5,r6
	158	sld r5,r5,r6
	159	#else
fe2f79db LM	160	sld r5,r5,r6
fe2f79db LM	161	srd r5,r5,r6
664318c3	162	#endif
fe2f79db LM	163	cmpdi cr7,r5,0 /* If r10 == 0, no c or null bytes
	164	have been found. */
	165	bne cr7,L(done_null)
	166
	167	mtcrf 0x01,r8
	168
	169	/* Are we now aligned to a quadword boundary? If so, skip to
	170	the main loop. Otherwise, go through the alignment code. */
	171
	172	bt 28,L(loop_null)
	173
	174	/* Handle WORD2 of pair. */
	175	ldu r12,8(r8)
	176	cmpb r5,r12,r0
	177	cmpdi cr7,r5,0
	178	bne cr7,L(done_null)
	179	b L(loop_null) /* We branch here (rather than falling through)
	180	to skip the nops due to heavy alignment
	181	of the loop below. */
	182
	183	/* Main loop to look for the end of the string. Since it's a
	184	small loop (< 8 instructions), align it to 32-bytes. */
	185	.p2align 5
	186	L(loop_null):
	187	/* Load two doublewords, compare and merge in a
	188	single register for speed. This is an attempt
	189	to speed up the null-checking process for bigger strings. */
	190	ld r12,8(r8)
	191	ldu r11,16(r8)
	192	cmpb r5,r12,r0
	193	cmpb r10,r11,r0
	194	or r6,r5,r10
	195	cmpdi cr7,r6,0
	196	beq cr7,L(loop_null)
	197
	198	/* OK, one (or both) of the doublewords contains a null byte. Check
	199	the first doubleword and decrement the address in case the first
	200	doubleword really contains a null byte. */
	201
	202	cmpdi cr6,r5,0
	203	addi r8,r8,-8
	204	bne cr6,L(done_null)
	205
	206	/* The null byte must be in the second doubleword. Adjust the address
	207	again and move the result of cmpb to r10 so we can calculate the
	208	pointer. */
	209
	210	mr r5,r10
	211	addi r8,r8,8
	212
	213	/* r5 has the output of the cmpb instruction, that is, it contains
	214	0xff in the same position as the null byte in the original
	215	doubleword from the string. Use that to calculate the pointer. */
	216	L(done_null):
664318c3 AM	217	#ifdef __LITTLE_ENDIAN__
	218	addi r0,r5,-1
	219	andc r0,r0,r5
	220	popcntd r0,r0
	221	#else
fe2f79db	222	cntlzd r0,r5 /* Count leading zeros before the match. */
664318c3	223	#endif
fe2f79db LM	224	srdi r0,r0,3 /* Convert leading zeros to bytes. */
	225	add r3,r8,r0 /* Return address of the matching null byte. */
	226	blr
6d15a5c2	227	END (STRCHR)
2d67d91a	228	weak_alias (strchr, index)
fe2f79db	229	libc_hidden_builtin_def (strchr)