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

/* Optimized strcmp implementation for POWER7/PowerPC32.
   Copyright (C) 2010, 2011 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
   <http://www.gnu.org/licenses/>.  */

#include <sysdep.h>
#include <bp-sym.h>
#include <bp-asm.h>

/* See strlen.s for comments on how the end-of-string testing works.  */

/* int [r3] strncmp (const char *s1 [r3],
		     const char *s2 [r4],
		     size_t size [r5])  */

EALIGN (BP_SYM(strncmp),5,0)

#define rTMP	r0
#define rRTN	r3
#define rSTR1	r3	/* first string arg */
#define rSTR2	r4	/* second string arg */
#define rN	r5	/* max string length */
/* Note:  The Bounded pointer support in this code is broken.  This code
   was inherited from PPC32 and that support was never completed.
   Current PPC gcc does not support -fbounds-check or -fbounded-pointers.  */
#define rWORD1	r6	/* current word in s1 */
#define rWORD2	r7	/* current word in s2 */
#define rWORD3	r10
#define rWORD4	r11
#define rFEFE	r8	/* constant 0xfefefeff (-0x01010101) */
#define r7F7F	r9	/* constant 0x7f7f7f7f */
#define rNEG	r10	/* ~(word in s1 | 0x7f7f7f7f) */
#define rBITDIF	r11	/* bits that differ in s1 & s2 words */

	dcbt	0,rSTR1
	nop
	or	rTMP,rSTR2,rSTR1
	lis	r7F7F,0x7f7f
	dcbt	0,rSTR2
	nop
	clrlwi.	rTMP,rTMP,30
	cmplwi	cr1,rN,0
	lis	rFEFE,-0x101
	bne	L(unaligned)
/* We are word alligned so set up for two loops.  first a word
   loop, then fall into the byte loop if any residual.  */
	srwi.	rTMP,rN,2
	clrlwi	rN,rN,30
	addi	rFEFE,rFEFE,-0x101
	addi	r7F7F,r7F7F,0x7f7f
	cmplwi	cr1,rN,0
	beq	L(unaligned)

	mtctr	rTMP
	lwz	rWORD1,0(rSTR1)
	lwz	rWORD2,0(rSTR2)
	b	L(g1)

L(g0):
	lwzu	rWORD1,4(rSTR1)
	bne	cr1,L(different)
	lwzu	rWORD2,4(rSTR2)
L(g1):	add	rTMP,rFEFE,rWORD1
	nor	rNEG,r7F7F,rWORD1
	bdz	L(tail)
	and.	rTMP,rTMP,rNEG
	cmpw	cr1,rWORD1,rWORD2
	beq	L(g0)

/* OK. We've hit the end of the string. We need to be careful that
   we don't compare two strings as different because of gunk beyond
   the end of the strings...  */

L(endstring):
	and	rTMP,r7F7F,rWORD1
	beq	cr1,L(equal)
	add	rTMP,rTMP,r7F7F
	xor.	rBITDIF,rWORD1,rWORD2

	andc	rNEG,rNEG,rTMP
	blt	L(highbit)
	cntlzw	rBITDIF,rBITDIF
	cntlzw	rNEG,rNEG
	addi	rNEG,rNEG,7
	cmpw	cr1,rNEG,rBITDIF
	sub	rRTN,rWORD1,rWORD2
	blt	cr1,L(equal)
	srawi	rRTN,rRTN,31
	ori	rRTN,rRTN,1
	blr
L(equal):
	li	rRTN,0
	blr

L(different):
	lwzu	rWORD1,-4(rSTR1)
	xor.	rBITDIF,rWORD1,rWORD2
	sub	rRTN,rWORD1,rWORD2
	blt	L(highbit)
	srawi	rRTN,rRTN,31
	ori	rRTN,rRTN,1
	blr
L(highbit):
	srwi	rWORD2,rWORD2,24
	srwi	rWORD1,rWORD1,24
	sub	rRTN,rWORD1,rWORD2
	blr


/* Oh well. In this case, we just do a byte-by-byte comparison.  */
	.align	4
L(tail):
	and.	rTMP,rTMP,rNEG
	cmpw	cr1,rWORD1,rWORD2
	bne	L(endstring)
	addi	rSTR1,rSTR1,4
	bne	cr1,L(different)
	addi	rSTR2,rSTR2,4
	cmplwi	cr1,rN,0
L(unaligned):
	mtctr	rN
	ble	cr1,L(ux)
L(uz):
	lbz	rWORD1,0(rSTR1)
	lbz	rWORD2,0(rSTR2)
	.align	4
L(u1):
	cmpwi	cr1,rWORD1,0
	bdz	L(u4)
	cmpw	rWORD1,rWORD2
	beq	cr1,L(u4)
	bne	L(u4)
	lbzu	rWORD3,1(rSTR1)
	lbzu	rWORD4,1(rSTR2)
	cmpwi	cr1,rWORD3,0
	bdz	L(u3)
	cmpw	rWORD3,rWORD4
	beq	cr1,L(u3)
	bne	L(u3)
	lbzu	rWORD1,1(rSTR1)
	lbzu	rWORD2,1(rSTR2)
	cmpwi	cr1,rWORD1,0
	bdz	L(u4)
	cmpw	rWORD1,rWORD2
	beq	cr1,L(u4)
	bne	L(u4)
	lbzu	rWORD3,1(rSTR1)
	lbzu	rWORD4,1(rSTR2)
	cmpwi	cr1,rWORD3,0
	bdz	L(u3)
	cmpw	rWORD3,rWORD4
	beq	cr1,L(u3)
	bne	L(u3)
	lbzu	rWORD1,1(rSTR1)
	lbzu	rWORD2,1(rSTR2)
	b	L(u1)

L(u3):  sub	rRTN,rWORD3,rWORD4
	blr
L(u4):	sub	rRTN,rWORD1,rWORD2
	blr
L(ux):
	li	rRTN,0
	blr
END (BP_SYM (strncmp))
libc_hidden_builtin_def (strncmp)
Commit	Line	Data
158db122	1	/* Optimized strcmp implementation for POWER7/PowerPC32.
4420675c	2	Copyright (C) 2010, 2011 Free Software Foundation, Inc.
158db122 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 PE	16	License along with the GNU C Library; if not, see
59ba27a6 PE	17	<http://www.gnu.org/licenses/>. */
158db122 LM	18
	19	#include <sysdep.h>
	20	#include <bp-sym.h>
	21	#include <bp-asm.h>
	22
	23	/* See strlen.s for comments on how the end-of-string testing works. */
	24
	25	/* int [r3] strncmp (const char *s1 [r3],
	26	const char *s2 [r4],
	27	size_t size [r5]) */
	28
22700377	29	EALIGN (BP_SYM(strncmp),5,0)
158db122 LM	30
	31	#define rTMP r0
	32	#define rRTN r3
	33	#define rSTR1 r3 /* first string arg */
	34	#define rSTR2 r4 /* second string arg */
	35	#define rN r5 /* max string length */
	36	/* Note: The Bounded pointer support in this code is broken. This code
ded5b9b7	37	was inherited from PPC32 and that support was never completed.
158db122 LM	38	Current PPC gcc does not support -fbounds-check or -fbounded-pointers. */
	39	#define rWORD1 r6 /* current word in s1 */
	40	#define rWORD2 r7 /* current word in s2 */
	41	#define rWORD3 r10
	42	#define rWORD4 r11
	43	#define rFEFE r8 /* constant 0xfefefeff (-0x01010101) */
	44	#define r7F7F r9 /* constant 0x7f7f7f7f */
	45	#define rNEG r10 /* ~(word in s1 \| 0x7f7f7f7f) */
	46	#define rBITDIF r11 /* bits that differ in s1 & s2 words */
	47
	48	dcbt 0,rSTR1
22700377	49	nop
158db122 LM	50	or rTMP,rSTR2,rSTR1
	51	lis r7F7F,0x7f7f
	52	dcbt 0,rSTR2
22700377	53	nop
158db122 LM	54	clrlwi. rTMP,rTMP,30
	55	cmplwi cr1,rN,0
	56	lis rFEFE,-0x101
	57	bne L(unaligned)
	58	/* We are word alligned so set up for two loops. first a word
	59	loop, then fall into the byte loop if any residual. */
	60	srwi. rTMP,rN,2
	61	clrlwi rN,rN,30
	62	addi rFEFE,rFEFE,-0x101
	63	addi r7F7F,r7F7F,0x7f7f
	64	cmplwi cr1,rN,0
	65	beq L(unaligned)
	66
	67	mtctr rTMP
	68	lwz rWORD1,0(rSTR1)
	69	lwz rWORD2,0(rSTR2)
	70	b L(g1)
	71
	72	L(g0):
	73	lwzu rWORD1,4(rSTR1)
	74	bne cr1,L(different)
	75	lwzu rWORD2,4(rSTR2)
	76	L(g1): add rTMP,rFEFE,rWORD1
	77	nor rNEG,r7F7F,rWORD1
	78	bdz L(tail)
	79	and. rTMP,rTMP,rNEG
	80	cmpw cr1,rWORD1,rWORD2
	81	beq L(g0)
	82
	83	/* OK. We've hit the end of the string. We need to be careful that
	84	we don't compare two strings as different because of gunk beyond
	85	the end of the strings... */
	86
	87	L(endstring):
	88	and rTMP,r7F7F,rWORD1
	89	beq cr1,L(equal)
	90	add rTMP,rTMP,r7F7F
	91	xor. rBITDIF,rWORD1,rWORD2
	92
	93	andc rNEG,rNEG,rTMP
	94	blt L(highbit)
	95	cntlzw rBITDIF,rBITDIF
	96	cntlzw rNEG,rNEG
	97	addi rNEG,rNEG,7
	98	cmpw cr1,rNEG,rBITDIF
	99	sub rRTN,rWORD1,rWORD2
	100	blt cr1,L(equal)
	101	srawi rRTN,rRTN,31
	102	ori rRTN,rRTN,1
	103	blr
	104	L(equal):
	105	li rRTN,0
	106	blr
	107
	108	L(different):
	109	lwzu rWORD1,-4(rSTR1)
	110	xor. rBITDIF,rWORD1,rWORD2
	111	sub rRTN,rWORD1,rWORD2
	112	blt L(highbit)
	113	srawi rRTN,rRTN,31
	114	ori rRTN,rRTN,1
	115	blr
	116	L(highbit):
	117	srwi rWORD2,rWORD2,24
118	srwi rWORD1,rWORD1,24
119	sub rRTN,rWORD1,rWORD2
120	blr
121
122
123	/* Oh well. In this case, we just do a byte-by-byte comparison. */
124	.align 4
125	L(tail):
126	and. rTMP,rTMP,rNEG
127	cmpw cr1,rWORD1,rWORD2
128	bne L(endstring)
129	addi rSTR1,rSTR1,4
130	bne cr1,L(different)
131	addi rSTR2,rSTR2,4
132	cmplwi cr1,rN,0
133	L(unaligned):
134	mtctr rN
135	ble cr1,L(ux)
136	L(uz):
137	lbz rWORD1,0(rSTR1)
138	lbz rWORD2,0(rSTR2)
139	.align 4
140	L(u1):
141	cmpwi cr1,rWORD1,0
142	bdz L(u4)
143	cmpw rWORD1,rWORD2
144	beq cr1,L(u4)
4420675c	145	bne L(u4)
158db122 LM	146	lbzu rWORD3,1(rSTR1)
158db122 LM	147	lbzu rWORD4,1(rSTR2)
158db122 LM	148	cmpwi cr1,rWORD3,0
	149	bdz L(u3)
	150	cmpw rWORD3,rWORD4
	151	beq cr1,L(u3)
4420675c	152	bne L(u3)
158db122 LM	153	lbzu rWORD1,1(rSTR1)
158db122 LM	154	lbzu rWORD2,1(rSTR2)
158db122 LM	155	cmpwi cr1,rWORD1,0
	156	bdz L(u4)
	157	cmpw rWORD1,rWORD2
	158	beq cr1,L(u4)
4420675c	159	bne L(u4)
158db122 LM	160	lbzu rWORD3,1(rSTR1)
158db122 LM	161	lbzu rWORD4,1(rSTR2)
158db122 LM	162	cmpwi cr1,rWORD3,0
	163	bdz L(u3)
	164	cmpw rWORD3,rWORD4
	165	beq cr1,L(u3)
4420675c	166	bne L(u3)
158db122 LM	167	lbzu rWORD1,1(rSTR1)
158db122 LM	168	lbzu rWORD2,1(rSTR2)
4420675c	169	b L(u1)
158db122 LM	170
	171	L(u3): sub rRTN,rWORD3,rWORD4
	172	blr
	173	L(u4): sub rRTN,rWORD1,rWORD2
	174	blr
	175	L(ux):
	176	li rRTN,0
	177	blr
	178	END (BP_SYM (strncmp))
	179	libc_hidden_builtin_def (strncmp)