[thirdparty/glibc.git] / sysdeps / powerpc / powerpc32 / power7 / strchr.S

/* Optimized strchr implementation for PowerPC32/POWER7 using cmpb insn.
   Copyright (C) 2010-2024 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>

/* int [r3] strchr (char *s [r3], int c [r4])  */
	.machine  power7
ENTRY (strchr)
	CALL_MCOUNT
	dcbt	0,r3
	clrrwi	r8,r3,2	      /* Align the address to word boundary.  */
	cmpwi	cr7,r4,0
	lwz	r12,0(r8)     /* Load word from memory.  */
	li	r0,0	      /* Word with null chars to use
				 with cmpb.  */

	rlwinm	r6,r3,3,27,28 /* Calculate padding.  */

	beq	cr7,L(null_match)

	/* Replicate byte to word.  */
	insrwi	r4,r4,8,16
	insrwi	r4,r4,16,0

	/* Now r4 has a word of c bytes and r0 has
	   a word 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 words left and right to discard the bits that are
	   not part of the string and to bring them back as zeros.  */
#ifdef __LITTLE_ENDIAN__
	srw	r10,r10,r6
	srw	r11,r11,r6
	slw	r10,r10,r6
	slw	r11,r11,r6
#else
	slw	r10,r10,r6
	slw	r11,r11,r6
	srw	r10,r10,r6
	srw	r11,r11,r6
#endif
	or	r5,r10,r11    /* OR the results to speed things up.  */
	cmpwi	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	29,L(loop)

	/* Handle WORD2 of pair.  */
	lwzu	r12,4(r8)
	cmpb	r10,r12,r4
	cmpb	r11,r12,r0
	or	r5,r10,r11
	cmpwi	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 words, compare and merge in a
	   single register for speed.  This is an attempt
	   to speed up the null-checking process for bigger strings.  */
	lwz	r12,4(r8)
	lwzu	r9,8(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
	cmpwi	cr7,r5,0
	beq	cr7,L(loop)

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

	cmpwi	cr6,r12,0
	addi	r8,r8,-4
	bne	cr6,L(done)

	/* The c/null byte must be in the second word.  Adjust the address
	   again and move the result of cmpb to r10/r11 so we can calculate
	   the pointer.  */

	mr	r10,r6
	mr	r11,r7
	addi	r8,r8,4

	/* r10/r11 have the output of the cmpb instructions, that is,
	   0xff in the same position as the c/null byte in the original
	   word from the string.  Use that to calculate the pointer.  */
L(done):
#ifdef __LITTLE_ENDIAN__
	addi    r3,r10,-1
	andc    r3,r3,r10
	popcntw	r0,r3
	addi    r4,r11,-1
	andc    r4,r4,r11
	cmplw	cr7,r3,r4
	bgt	cr7,L(no_match)
#else
	cntlzw	r0,r10	      /* Count leading zeros before c matches.  */
	cmplw	cr7,r11,r10
	bgt	cr7,L(no_match)
#endif
	srwi	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 word of null bytes.  */

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

	/* Move the words left and right to discard the bits that are
	   not part of the string and bring them back as zeros.  */
#ifdef __LITTLE_ENDIAN__
	srw	r5,r5,r6
	slw	r5,r5,r6
#else
	slw	r5,r5,r6
	srw	r5,r5,r6
#endif
	cmpwi	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 doubleword boundary?  If so, skip to
	   the main loop.  Otherwise, go through the alignment code.  */

	bt	29,L(loop_null)

	/* Handle WORD2 of pair.  */
	lwzu	r12,4(r8)
	cmpb    r5,r12,r0
	cmpwi	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 words, compare and merge in a
	   single register for speed.  This is an attempt
	   to speed up the null-checking process for bigger strings.  */
	lwz	r12,4(r8)
	lwzu    r11,8(r8)
	cmpb	r5,r12,r0
	cmpb	r10,r11,r0
	or	r6,r5,r10
	cmpwi	cr7,r6,0
	beq	cr7,L(loop_null)

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

	cmpwi	cr6,r5,0
	addi	r8,r8,-4
	bne	cr6,L(done_null)

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

	mr	r5,r10
	addi	r8,r8,4

	/* r5 has the output of the cmpb instruction, that is, it contains
	   0xff in the same position as the null byte in the original
	   word from the string.  Use that to calculate the pointer.  */
L(done_null):
#ifdef __LITTLE_ENDIAN__
	addi    r0,r5,-1
	andc    r0,r0,r5
	popcntw	r0,r0
#else
	cntlzw	r0,r5	      /* Count leading zeros before the match.  */
#endif
	srwi	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 PowerPC32/POWER7 using cmpb insn.
dff8da6b	2	Copyright (C) 2010-2024 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 LM	20
	21	/* int [r3] strchr (char s [r3], int c [r4]) /
	22	.machine power7
b5510883	23	ENTRY (strchr)
fe2f79db LM	24	CALL_MCOUNT
	25	dcbt 0,r3
	26	clrrwi r8,r3,2 /* Align the address to word boundary. */
	27	cmpwi cr7,r4,0
	28	lwz r12,0(r8) /* Load word from memory. */
	29	li r0,0 /* Word with null chars to use
	30	with cmpb. */
	31
	32	rlwinm r6,r3,3,27,28 /* Calculate padding. */
	33
	34	beq cr7,L(null_match)
	35
	36	/* Replicate byte to word. */
d298c416 AZ	37	insrwi r4,r4,8,16
d298c416 AZ	38	insrwi r4,r4,16,0
fe2f79db LM	39
	40	/* Now r4 has a word of c bytes and r0 has
	41	a word of null bytes. */
	42
	43	cmpb r10,r12,r4 /* Compare each byte against c byte. */
	44	cmpb r11,r12,r0 /* Compare each byte against null byte. */
	45
	46	/* Move the words left and right to discard the bits that are
	47	not part of the string and to bring them back as zeros. */
664318c3 AM	48	#ifdef __LITTLE_ENDIAN__
	49	srw r10,r10,r6
	50	srw r11,r11,r6
	51	slw r10,r10,r6
	52	slw r11,r11,r6
	53	#else
fe2f79db LM	54	slw r10,r10,r6
	55	slw r11,r11,r6
	56	srw r10,r10,r6
	57	srw r11,r11,r6
664318c3	58	#endif
fe2f79db LM	59	or r5,r10,r11 /* OR the results to speed things up. */
	60	cmpwi cr7,r5,0 /* If r5 == 0, no c or null bytes
	61	have been found. */
	62	bne cr7,L(done)
	63
	64	mtcrf 0x01,r8
	65
	66	/* Are we now aligned to a doubleword boundary? If so, skip to
	67	the main loop. Otherwise, go through the alignment code. */
	68
	69	bt 29,L(loop)
	70
	71	/* Handle WORD2 of pair. */
	72	lwzu r12,4(r8)
664318c3	73	cmpb r10,r12,r4
fe2f79db LM	74	cmpb r11,r12,r0
	75	or r5,r10,r11
	76	cmpwi cr7,r5,0
	77	bne cr7,L(done)
	78	b L(loop) /* We branch here (rather than falling through)
	79	to skip the nops due to heavy alignment
	80	of the loop below. */
	81
	82	.p2align 5
	83	L(loop):
	84	/* Load two words, compare and merge in a
	85	single register for speed. This is an attempt
	86	to speed up the null-checking process for bigger strings. */
	87	lwz r12,4(r8)
	88	lwzu r9,8(r8)
	89	cmpb r10,r12,r4
	90	cmpb r11,r12,r0
	91	cmpb r6,r9,r4
	92	cmpb r7,r9,r0
	93	or r12,r10,r11
	94	or r9,r6,r7
	95	or r5,r12,r9
	96	cmpwi cr7,r5,0
	97	beq cr7,L(loop)
	98
	99	/* OK, one (or both) of the words contains a c/null byte. Check
	100	the first word and decrement the address in case the first
	101	word really contains a c/null byte. */
	102
	103	cmpwi cr6,r12,0
	104	addi r8,r8,-4
	105	bne cr6,L(done)
	106
	107	/* The c/null byte must be in the second word. Adjust the address
664318c3 AM	108	again and move the result of cmpb to r10/r11 so we can calculate
664318c3 AM	109	the pointer. */
fe2f79db LM	110
	111	mr r10,r6
	112	mr r11,r7
	113	addi r8,r8,4
	114
664318c3	115	/* r10/r11 have the output of the cmpb instructions, that is,
fe2f79db LM	116	0xff in the same position as the c/null byte in the original
	117	word from the string. Use that to calculate the pointer. */
	118	L(done):
664318c3 AM	119	#ifdef __LITTLE_ENDIAN__
	120	addi r3,r10,-1
	121	andc r3,r3,r10
	122	popcntw r0,r3
	123	addi r4,r11,-1
	124	andc r4,r4,r11
	125	cmplw cr7,r3,r4
	126	bgt cr7,L(no_match)
	127	#else
	128	cntlzw r0,r10 /* Count leading zeros before c matches. */
	129	cmplw cr7,r11,r10
fe2f79db	130	bgt cr7,L(no_match)
664318c3 AM	131	#endif
664318c3 AM	132	srwi r0,r0,3 /* Convert leading zeros to bytes. */
fe2f79db LM	133	add r3,r8,r0 /* Return address of the matching c byte
	134	or null in case c was not found. */
	135	blr
	136
	137	.align 4
	138	L(no_match):
	139	li r3,0
	140	blr
	141
	142	/* We are here because strchr was called with a null byte. */
	143	.align 4
	144	L(null_match):
	145	/* r0 has a word of null bytes. */
	146
	147	cmpb r5,r12,r0 /* Compare each byte against null bytes. */
	148
	149	/* Move the words left and right to discard the bits that are
664318c3 AM	150	not part of the string and bring them back as zeros. */
	151	#ifdef __LITTLE_ENDIAN__
	152	srw r5,r5,r6
	153	slw r5,r5,r6
	154	#else
fe2f79db LM	155	slw r5,r5,r6
fe2f79db LM	156	srw r5,r5,r6
664318c3	157	#endif
fe2f79db LM	158	cmpwi cr7,r5,0 /* If r10 == 0, no c or null bytes
	159	have been found. */
	160	bne cr7,L(done_null)
	161
	162	mtcrf 0x01,r8
	163
	164	/* Are we now aligned to a doubleword boundary? If so, skip to
	165	the main loop. Otherwise, go through the alignment code. */
	166
	167	bt 29,L(loop_null)
	168
	169	/* Handle WORD2 of pair. */
	170	lwzu r12,4(r8)
	171	cmpb r5,r12,r0
	172	cmpwi cr7,r5,0
	173	bne cr7,L(done_null)
	174	b L(loop_null) /* We branch here (rather than falling through)
	175	to skip the nops due to heavy alignment
	176	of the loop below. */
	177
	178	/* Main loop to look for the end of the string. Since it's a
	179	small loop (< 8 instructions), align it to 32-bytes. */
	180	.p2align 5
	181	L(loop_null):
	182	/* Load two words, compare and merge in a
	183	single register for speed. This is an attempt
	184	to speed up the null-checking process for bigger strings. */
	185	lwz r12,4(r8)
	186	lwzu r11,8(r8)
	187	cmpb r5,r12,r0
	188	cmpb r10,r11,r0
	189	or r6,r5,r10
	190	cmpwi cr7,r6,0
	191	beq cr7,L(loop_null)
	192
	193	/* OK, one (or both) of the words contains a null byte. Check
	194	the first word and decrement the address in case the first
	195	word really contains a null byte. */
	196
	197	cmpwi cr6,r5,0
	198	addi r8,r8,-4
	199	bne cr6,L(done_null)
	200
	201	/* The null byte must be in the second word. Adjust the address
	202	again and move the result of cmpb to r10 so we can calculate the
	203	pointer. */
	204
	205	mr r5,r10
	206	addi r8,r8,4
	207
	208	/* r5 has the output of the cmpb instruction, that is, it contains
	209	0xff in the same position as the null byte in the original
	210	word from the string. Use that to calculate the pointer. */
	211	L(done_null):
664318c3 AM	212	#ifdef __LITTLE_ENDIAN__
	213	addi r0,r5,-1
	214	andc r0,r0,r5
	215	popcntw r0,r0
	216	#else
fe2f79db	217	cntlzw r0,r5 /* Count leading zeros before the match. */
664318c3	218	#endif
fe2f79db LM	219	srwi r0,r0,3 /* Convert leading zeros to bytes. */
	220	add r3,r8,r0 /* Return address of the matching null byte. */
	221	blr
b5510883 JM	222	END (strchr)
b5510883 JM	223	weak_alias (strchr, index)
fe2f79db	224	libc_hidden_builtin_def (strchr)