aboutsummaryrefslogtreecommitdiff
path: root/sysdeps/powerpc/powerpc64/strcmp.S
blob: 06cc2cfe42b57c781b95f9171d5d1ba5198a4a4f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
/* Optimized strcmp implementation for PowerPC64.
   Copyright (C) 1997, 1999, 2000, 2002, 2003, 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#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] strcmp (const char *s1 [r3], const char *s2 [r4])  */

EALIGN (BP_SYM(strcmp), 4, 0)
	CALL_MCOUNT 2

#define rTMP	r0
#define rRTN	r3
#define rSTR1	r3	/* first string arg */
#define rSTR2	r4	/* second string arg */
/* 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.
   These artifacts are left in the code as a reminder in case we need
   bounded pointer support in the future.  */
#if __BOUNDED_POINTERS__
# define rHIGH1	r11
# define rHIGH2 r12
#endif
#define rWORD1	r5	/* current word in s1 */
#define rWORD2	r6	/* current word in s2 */
#define rFEFE	r7	/* constant 0xfefefefefefefeff (-0x0101010101010101) */
#define r7F7F	r8	/* constant 0x7f7f7f7f7f7f7f7f */
#define rNEG	r9	/* ~(word in s1 | 0x7f7f7f7f7f7f7f7f) */
#define rBITDIF	r10	/* bits that differ in s1 & s2 words */

	CHECK_BOUNDS_LOW (rSTR1, rTMP, rHIGH1)
	CHECK_BOUNDS_LOW (rSTR2, rTMP, rHIGH2)

	dcbt	0,rSTR1
	or	rTMP, rSTR2, rSTR1
	dcbt	0,rSTR2
	clrldi.	rTMP, rTMP, 61
	lis	rFEFE, -0x101
	bne	L(unaligned)

	ld	rWORD1, 0(rSTR1)
	ld	rWORD2, 0(rSTR2)
	lis	r7F7F, 0x7f7f
	addi	rFEFE, rFEFE, -0x101
	addi	r7F7F, r7F7F, 0x7f7f
	sldi	rTMP, rFEFE, 32
	insrdi	r7F7F, r7F7F, 32, 0
	add	rFEFE, rFEFE, rTMP
	b	L(g1)

L(g0):	ldu	rWORD1, 8(rSTR1)
	bne	cr1, L(different)
	ldu	rWORD2, 8(rSTR2)
L(g1):	add	rTMP, rFEFE, rWORD1
	nor	rNEG, r7F7F, rWORD1

	and.	rTMP, rTMP, rNEG
	cmpd	cr1, rWORD1, rWORD2
	beq+	L(g0)
L(endstring):
/* 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...  */
	and	rTMP, r7F7F, rWORD1
	beq	cr1, L(equal)
	add	rTMP, rTMP, r7F7F
	xor.	rBITDIF, rWORD1, rWORD2

	andc	rNEG, rNEG, rTMP
	blt-	L(highbit)
	cntlzd	rBITDIF, rBITDIF
	cntlzd	rNEG, rNEG
	addi	rNEG, rNEG, 7
	cmpd	cr1, rNEG, rBITDIF
	sub	rRTN, rWORD1, rWORD2
	blt-	cr1, L(equal)
	sradi	rRTN, rRTN, 63
	ori	rRTN, rRTN, 1
	blr
L(equal):
	li	rRTN, 0
	/* GKM FIXME: check high bounds.  */
	blr

L(different):
	ld	rWORD1, -8(rSTR1)
	xor.	rBITDIF, rWORD1, rWORD2
	sub	rRTN, rWORD1, rWORD2
	blt-	L(highbit)
	sradi	rRTN, rRTN, 63
	ori	rRTN, rRTN, 1
	blr
L(highbit):
	srdi	rWORD2, rWORD2, 56
	srdi	rWORD1, rWORD1, 56
	sub	rRTN, rWORD1, rWORD2
	/* GKM FIXME: check high bounds.  */
	blr


/* Oh well.  In this case, we just do a byte-by-byte comparison.  */
	.align 4
L(unaligned):
	lbz	rWORD1, 0(rSTR1)
	lbz	rWORD2, 0(rSTR2)
	b	L(u1)

L(u0):	lbzu	rWORD1, 1(rSTR1)
	bne-	L(u4)
	lbzu	rWORD2, 1(rSTR2)
L(u1):	cmpwi	cr1, rWORD1, 0
	beq-	cr1, L(u3)
	cmpd	rWORD1, rWORD2
	bne-	L(u3)
	lbzu	rWORD1, 1(rSTR1)
	lbzu	rWORD2, 1(rSTR2)
	cmpdi	cr1, rWORD1, 0
	cmpd	rWORD1, rWORD2
	bne+	cr1, L(u0)
L(u3):	sub	rRTN, rWORD1, rWORD2
	/* GKM FIXME: check high bounds.  */
	blr
L(u4):	lbz	rWORD1, -1(rSTR1)
	sub	rRTN, rWORD1, rWORD2
	/* GKM FIXME: check high bounds.  */
	blr
END (BP_SYM (strcmp))
libc_hidden_builtin_def (strcmp)