1/* strcmp with unaligned loads
2 Copyright (C) 2013-2023 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