1/* strcmp with unaligned loads
2   Copyright (C) 2013-2022 Free Software Foundation, Inc.
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
16   License along with the GNU C Library; if not, see
17   <https://www.gnu.org/licenses/>.  */
18
19#include <isa-level.h>
20
21/* Continue building as ISA level 2.  We use this as ISA V2 default
22   because strcmp-sse42 uses pcmpstri (slow on some SSE4.2
23   processors) and this implementation is potenially faster than
24   strcmp-sse42 (aside from the slower page cross case).  */
25#if ISA_SHOULD_BUILD (2)
26
27# define STRCMP_ISA	_sse2_unaligned
28# include "strcmp-naming.h"
29
30# include "sysdep.h"
31
32ENTRY (STRCMP)
33	movl	%edi, %eax
34	xorl	%edx, %edx
35	pxor	%xmm7, %xmm7
36	orl	%esi, %eax
37	andl	$4095, %eax
38	cmpl	$4032, %eax
39	jg	L(cross_page)
40	movdqu	(%rdi), %xmm1
41	movdqu	(%rsi), %xmm0
42	pcmpeqb	%xmm1, %xmm0
43	pminub	%xmm1, %xmm0
44	pxor	%xmm1, %xmm1
45	pcmpeqb	%xmm1, %xmm0
46	pmovmskb	%xmm0, %eax
47	testq	%rax, %rax
48	je	L(next_48_bytes)
49L(return):
50	bsfq	%rax, %rdx
51	movzbl	(%rdi, %rdx), %eax
52	movzbl	(%rsi, %rdx), %edx
53	subl	%edx, %eax
54	ret
55
56	.p2align 4
57L(next_48_bytes):
58	movdqu	16(%rdi), %xmm6
59	movdqu	16(%rsi), %xmm3
60	movdqu	32(%rdi), %xmm5
61	pcmpeqb	%xmm6, %xmm3
62	movdqu	32(%rsi), %xmm2
63	pminub	%xmm6, %xmm3
64	pcmpeqb	%xmm1, %xmm3
65	movdqu	48(%rdi), %xmm4
66	pcmpeqb	%xmm5, %xmm2
67	pmovmskb	%xmm3, %edx
68	movdqu	48(%rsi), %xmm0
69	pminub	%xmm5, %xmm2
70	pcmpeqb	%xmm1, %xmm2
71	pcmpeqb	%xmm4, %xmm0
72	pmovmskb	%xmm2, %eax
73	salq	$16, %rdx
74	pminub	%xmm4, %xmm0
75	pcmpeqb	%xmm1, %xmm0
76	salq	$32, %rax
77	orq	%rdx, %rax
78	pmovmskb	%xmm0, %ecx
79	movq	%rcx, %rdx
80	salq	$48, %rdx
81	orq	%rdx, %rax
82	jne	L(return)
83L(main_loop_header):
84	leaq	64(%rdi), %rdx
85	movl	$4096, %ecx
86	pxor	%xmm9, %xmm9
87	andq	$-64, %rdx
88	subq	%rdi, %rdx
89	leaq	(%rdi, %rdx), %rax
90	addq	%rsi, %rdx
91	movq	%rdx, %rsi
92	andl	$4095, %esi
93	subq	%rsi, %rcx
94	shrq	$6, %rcx
95	movq	%rcx, %rsi
96	jmp	L(loop_start)
97
98	.p2align 4
99L(loop):
100	addq	$64, %rax
101	addq	$64, %rdx
102L(loop_start):
103	testq	%rsi, %rsi
104	leaq	-1(%rsi), %rsi
105	je	L(loop_cross_page)
106L(back_to_loop):
107	movdqu	(%rdx), %xmm0
108	movdqu	16(%rdx), %xmm1
109	movdqa	(%rax), %xmm2
110	movdqa	16(%rax), %xmm3
111	pcmpeqb	%xmm2, %xmm0
112	movdqu	32(%rdx), %xmm5
113	pcmpeqb	%xmm3, %xmm1
114	pminub	%xmm2, %xmm0
115	movdqu	48(%rdx), %xmm6
116	pminub	%xmm3, %xmm1
117	movdqa	32(%rax), %xmm2
118	pminub	%xmm1, %xmm0
119	movdqa	48(%rax), %xmm3
120	pcmpeqb	%xmm2, %xmm5
121	pcmpeqb	%xmm3, %xmm6
122	pminub	%xmm2, %xmm5
123	pminub	%xmm3, %xmm6
124	pminub	%xmm5, %xmm0
125	pminub	%xmm6, %xmm0
126	pcmpeqb	%xmm7, %xmm0
127	pmovmskb	%xmm0, %ecx
128	testl	%ecx, %ecx
129	je	L(loop)
130	pcmpeqb	%xmm7, %xmm5
131	movdqu	(%rdx), %xmm0
132	pcmpeqb	%xmm7, %xmm1
133	movdqa	(%rax), %xmm2
134	pcmpeqb	%xmm2, %xmm0
135	pminub	%xmm2, %xmm0
136	pcmpeqb	%xmm7, %xmm6
137	pcmpeqb	%xmm7, %xmm0
138	pmovmskb	%xmm1, %ecx
139	pmovmskb	%xmm5, %r8d
140	pmovmskb	%xmm0, %edi
141	salq	$16, %rcx
142	salq	$32, %r8
143	pmovmskb	%xmm6, %esi
144	orq	%r8, %rcx
145	orq	%rdi, %rcx
146	salq	$48, %rsi
147	orq	%rsi, %rcx
148	bsfq	%rcx, %rcx
149	movzbl	(%rax, %rcx), %eax
150	movzbl	(%rdx, %rcx), %edx
151	subl	%edx, %eax
152	ret
153
154	.p2align 4
155L(loop_cross_page):
156	xor	%r10, %r10
157	movq	%rdx, %r9
158	and	$63, %r9
159	subq	%r9, %r10
160
161	movdqa	(%rdx, %r10), %xmm0
162	movdqa	16(%rdx, %r10), %xmm1
163	movdqu	(%rax, %r10), %xmm2
164	movdqu	16(%rax, %r10), %xmm3
165	pcmpeqb	%xmm2, %xmm0
166	movdqa	32(%rdx, %r10), %xmm5
167	pcmpeqb	%xmm3, %xmm1
168	pminub	%xmm2, %xmm0
169	movdqa	48(%rdx, %r10), %xmm6
170	pminub	%xmm3, %xmm1
171	movdqu	32(%rax, %r10), %xmm2
172	movdqu	48(%rax, %r10), %xmm3
173	pcmpeqb	%xmm2, %xmm5
174	pcmpeqb	%xmm3, %xmm6
175	pminub	%xmm2, %xmm5
176	pminub	%xmm3, %xmm6
177
178	pcmpeqb	%xmm7, %xmm0
179	pcmpeqb	%xmm7, %xmm1
180	pcmpeqb	%xmm7, %xmm5
181	pcmpeqb	%xmm7, %xmm6
182
183	pmovmskb	%xmm1, %ecx
184	pmovmskb	%xmm5, %r8d
185	pmovmskb	%xmm0, %edi
186	salq	$16, %rcx
187	salq	$32, %r8
188	pmovmskb	%xmm6, %esi
189	orq	%r8, %rdi
190	orq	%rcx, %rdi
191	salq	$48, %rsi
192	orq	%rsi, %rdi
193	movq	%r9, %rcx
194	movq	$63, %rsi
195	shrq	%cl, %rdi
196	test	%rdi, %rdi
197	je	L(back_to_loop)
198	bsfq	%rdi, %rcx
199	movzbl	(%rax, %rcx), %eax
200	movzbl	(%rdx, %rcx), %edx
201	subl	%edx, %eax
202	ret
203
204	.p2align 4
205L(cross_page_loop):
206	cmpb	%cl, %al
207	jne	L(different)
208	addq	$1, %rdx
209	cmpq	$64, %rdx
210	je	L(main_loop_header)
211L(cross_page):
212	movzbl	(%rdi, %rdx), %eax
213	movzbl	(%rsi, %rdx), %ecx
214	testb	%al, %al
215	jne	L(cross_page_loop)
216	xorl	%eax, %eax
217L(different):
218	subl	%ecx, %eax
219	ret
220END (STRCMP)
221#endif
222