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

/* Optimized strchr implementation for PowerPC32/POWER7 using cmpb insn.
   Copyright (C) 2010-2013 Free Software Foundation, Inc.
   Contributed by Luis Machado <luisgpm@br.ibm.com>.
   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/>.  */

#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.  */
	rlwimi	r4,r4,8,16,23
	rlwimi	r4,r4,16,0,15

	/* 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.  */

	slw	r10,r10,r6
	slw	r11,r11,r6
	srw	r10,r10,r6
	srw	r11,r11,r6
	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 so we can calculate the
	   pointer.  */

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

	/* r5 has the output of the cmpb instruction, that is, it contains
	   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):
	cntlzw	r4,r10	      /* Count leading zeroes before c matches.  */
	cntlzw	r0,r11	      /* Count leading zeroes before null matches.  */
	cmplw	cr7,r4,r0
	bgt	cr7,L(no_match)
	srwi	r0,r4,3	      /* Convert leading zeroes 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 to bring them back as zeros.  */

	slw	r5,r5,r6
	srw	r5,r5,r6
	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):
	cntlzw	r0,r5	      /* Count leading zeros before the match.  */
	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.
568035b7	2	Copyright (C) 2010-2013 Free Software Foundation, Inc.
fe2f79db LM	3	Contributed by Luis Machado <luisgpm@br.ibm.com>.
	4	This file is part of the GNU C Library.
	5
	6	The GNU C Library is free software; you can redistribute it and/or
	7	modify it under the terms of the GNU Lesser General Public
	8	License as published by the Free Software Foundation; either
	9	version 2.1 of the License, or (at your option) any later version.
	10
	11	The GNU C Library is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	14	Lesser General Public License for more details.
	15
	16	You should have received a copy of the GNU Lesser General Public
59ba27a6 PE	17	License along with the GNU C Library; if not, see
59ba27a6 PE	18	<http://www.gnu.org/licenses/>. */
fe2f79db LM	19
fe2f79db LM	20	#include <sysdep.h>
fe2f79db LM	21
	22	/* int [r3] strchr (char s [r3], int c [r4]) /
	23	.machine power7
b5510883	24	ENTRY (strchr)
fe2f79db LM	25	CALL_MCOUNT
	26	dcbt 0,r3
	27	clrrwi r8,r3,2 /* Align the address to word boundary. */
	28	cmpwi cr7,r4,0
	29	lwz r12,0(r8) /* Load word from memory. */
	30	li r0,0 /* Word with null chars to use
	31	with cmpb. */
	32
	33	rlwinm r6,r3,3,27,28 /* Calculate padding. */
	34
	35	beq cr7,L(null_match)
	36
	37	/* Replicate byte to word. */
	38	rlwimi r4,r4,8,16,23
	39	rlwimi r4,r4,16,0,15
	40
	41	/* Now r4 has a word of c bytes and r0 has
	42	a word of null bytes. */
	43
	44	cmpb r10,r12,r4 /* Compare each byte against c byte. */
	45	cmpb r11,r12,r0 /* Compare each byte against null byte. */
	46
	47	/* Move the words left and right to discard the bits that are
	48	not part of the string and to bring them back as zeros. */
	49
	50	slw r10,r10,r6
	51	slw r11,r11,r6
	52	srw r10,r10,r6
	53	srw r11,r11,r6
	54	or r5,r10,r11 /* OR the results to speed things up. */
	55	cmpwi cr7,r5,0 /* If r5 == 0, no c or null bytes
	56	have been found. */
	57	bne cr7,L(done)
	58
	59	mtcrf 0x01,r8
	60
	61	/* Are we now aligned to a doubleword boundary? If so, skip to
	62	the main loop. Otherwise, go through the alignment code. */
	63
	64	bt 29,L(loop)
	65
	66	/* Handle WORD2 of pair. */
	67	lwzu r12,4(r8)
	68	cmpb r10,r12,r4
	69	cmpb r11,r12,r0
	70	or r5,r10,r11
	71	cmpwi cr7,r5,0
	72	bne cr7,L(done)
	73	b L(loop) /* We branch here (rather than falling through)
	74	to skip the nops due to heavy alignment
	75	of the loop below. */
	76
	77	.p2align 5
	78	L(loop):
	79	/* Load two words, compare and merge in a
	80	single register for speed. This is an attempt
	81	to speed up the null-checking process for bigger strings. */
	82	lwz r12,4(r8)
	83	lwzu r9,8(r8)
	84	cmpb r10,r12,r4
	85	cmpb r11,r12,r0
	86	cmpb r6,r9,r4
	87	cmpb r7,r9,r0
	88	or r12,r10,r11
89	or r9,r6,r7
90	or r5,r12,r9
91	cmpwi cr7,r5,0
92	beq cr7,L(loop)
93
94	/* OK, one (or both) of the words contains a c/null byte. Check
95	the first word and decrement the address in case the first
96	word really contains a c/null byte. */
97
98	cmpwi cr6,r12,0
99	addi r8,r8,-4
100	bne cr6,L(done)
101
102	/* The c/null byte must be in the second word. Adjust the address
103	again and move the result of cmpb to r10 so we can calculate the
104	pointer. */
105
106	mr r10,r6
107	mr r11,r7
108	addi r8,r8,4
109
110	/* r5 has the output of the cmpb instruction, that is, it contains
111	0xff in the same position as the c/null byte in the original
112	word from the string. Use that to calculate the pointer. */
113	L(done):
114	cntlzw r4,r10 /* Count leading zeroes before c matches. */
115	cntlzw r0,r11 /* Count leading zeroes before null matches. */
116	cmplw cr7,r4,r0
117	bgt cr7,L(no_match)
118	srwi r0,r4,3 /* Convert leading zeroes to bytes. */
119	add r3,r8,r0 /* Return address of the matching c byte
120	or null in case c was not found. */
121	blr
122
123	.align 4
124	L(no_match):
125	li r3,0
126	blr
127
128	/* We are here because strchr was called with a null byte. */
129	.align 4
130	L(null_match):
131	/* r0 has a word of null bytes. */
132
133	cmpb r5,r12,r0 /* Compare each byte against null bytes. */
134
135	/* Move the words left and right to discard the bits that are
136	not part of the string and to bring them back as zeros. */
137
138	slw r5,r5,r6
139	srw r5,r5,r6
140	cmpwi cr7,r5,0 /* If r10 == 0, no c or null bytes
141	have been found. */
142	bne cr7,L(done_null)
143
144	mtcrf 0x01,r8
145
146	/* Are we now aligned to a doubleword boundary? If so, skip to
147	the main loop. Otherwise, go through the alignment code. */
148
149	bt 29,L(loop_null)
150
151	/* Handle WORD2 of pair. */
152	lwzu r12,4(r8)
153	cmpb r5,r12,r0
154	cmpwi cr7,r5,0
155	bne cr7,L(done_null)
156	b L(loop_null) /* We branch here (rather than falling through)
157	to skip the nops due to heavy alignment
158	of the loop below. */
159
160	/* Main loop to look for the end of the string. Since it's a
161	small loop (< 8 instructions), align it to 32-bytes. */
162	.p2align 5
163	L(loop_null):
164	/* Load two words, compare and merge in a
165	single register for speed. This is an attempt
166	to speed up the null-checking process for bigger strings. */
167	lwz r12,4(r8)
168	lwzu r11,8(r8)
169	cmpb r5,r12,r0
170	cmpb r10,r11,r0
171	or r6,r5,r10
172	cmpwi cr7,r6,0
173	beq cr7,L(loop_null)
174
175	/* OK, one (or both) of the words contains a null byte. Check
176	the first word and decrement the address in case the first
177	word really contains a null byte. */
178
179	cmpwi cr6,r5,0
180	addi r8,r8,-4
181	bne cr6,L(done_null)
182
183	/* The null byte must be in the second word. Adjust the address
184	again and move the result of cmpb to r10 so we can calculate the
185	pointer. */
186
187	mr r5,r10
188	addi r8,r8,4
189
190	/* r5 has the output of the cmpb instruction, that is, it contains
191	0xff in the same position as the null byte in the original
192	word from the string. Use that to calculate the pointer. */
193	L(done_null):
194	cntlzw r0,r5 /* Count leading zeros before the match. */
195	srwi r0,r0,3 /* Convert leading zeros to bytes. */
196	add r3,r8,r0 /* Return address of the matching null byte. */
197	blr
b5510883 JM	198	END (strchr)
b5510883 JM	199	weak_alias (strchr, index)
fe2f79db	200	libc_hidden_builtin_def (strchr)