summaryrefslogtreecommitdiff
path: root/sysdeps/x86_64/multiarch/strcmp-avx2.S
blob: b32a5e3528b24ff1c7c14599adee874382eedc11 (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
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
/* strcmp/wcscmp/strncmp/wcsncmp optimized with AVX2.
   Copyright (C) 2018-2019 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/>.  */

#if IS_IN (libc)

# include <sysdep.h>

# ifndef STRCMP
#  define STRCMP	__strcmp_avx2
# endif

# define PAGE_SIZE	4096

/* VEC_SIZE = Number of bytes in a ymm register */
# define VEC_SIZE	32

/* Shift for dividing by (VEC_SIZE * 4).  */
# define DIVIDE_BY_VEC_4_SHIFT	7
# if (VEC_SIZE * 4) != (1 << DIVIDE_BY_VEC_4_SHIFT)
#  error (VEC_SIZE * 4) != (1 << DIVIDE_BY_VEC_4_SHIFT)
# endif

# ifdef USE_AS_WCSCMP
/* Compare packed dwords.  */
#  define VPCMPEQ	vpcmpeqd
/* Compare packed dwords and store minimum.  */
#  define VPMINU	vpminud
/* 1 dword char == 4 bytes.  */
#  define SIZE_OF_CHAR	4
# else
/* Compare packed bytes.  */
#  define VPCMPEQ	vpcmpeqb
/* Compare packed bytes and store minimum.  */
#  define VPMINU	vpminub
/* 1 byte char == 1 byte.  */
#  define SIZE_OF_CHAR	1
# endif

# ifndef VZEROUPPER
#  define VZEROUPPER	vzeroupper
# endif

/* Warning!
           wcscmp/wcsncmp have to use SIGNED comparison for elements.
           strcmp/strncmp have to use UNSIGNED comparison for elements.
*/

/* The main idea of the string comparison (byte or dword) using AVX2
   consists of comparing (VPCMPEQ) two ymm vectors. The latter can be on
   either packed bytes or dwords depending on USE_AS_WCSCMP. In order
   to check the null char, algorithm keeps the matched bytes/dwords,
   requiring two more AVX2 instructions (VPMINU and VPCMPEQ). In general,
   the costs of comparing VEC_SIZE bytes (32-bytes) are two VPCMPEQ and
   one VPMINU instructions, together with movdqu and testl instructions.
   Main loop (away from from page boundary) compares 4 vectors are a time,
   effectively comparing 4 x VEC_SIZE bytes (128 bytes) on each loop.

   The routine strncmp/wcsncmp (enabled by defining USE_AS_STRNCMP) logic
   is the same as strcmp, except that an a maximum offset is tracked.  If
   the maximum offset is reached before a difference is found, zero is
   returned.  */

	.section .text.avx,"ax",@progbits
ENTRY (STRCMP)
# ifdef USE_AS_STRNCMP
	/* Check for simple cases (0 or 1) in offset.  */
	cmp	$1, %RDX_LP
	je	L(char0)
	jb	L(zero)
#  ifdef USE_AS_WCSCMP
	/* Convert units: from wide to byte char.  */
	shl	$2, %RDX_LP
#  endif
	/* Register %r11 tracks the maximum offset.  */
	mov	%RDX_LP, %R11_LP
# endif
	movl	%edi, %eax
	xorl	%edx, %edx
	/* Make %ymm7 all zeros in this function.  */
	vpxor	%ymm7, %ymm7, %ymm7
	orl	%esi, %eax
	andl	$(PAGE_SIZE - 1), %eax
	cmpl	$(PAGE_SIZE - (VEC_SIZE * 4)), %eax
	jg	L(cross_page)
	/* Start comparing 4 vectors.  */
	vmovdqu	(%rdi), %ymm1
	VPCMPEQ	(%rsi), %ymm1, %ymm0
	VPMINU	%ymm1, %ymm0, %ymm0
	VPCMPEQ	%ymm7, %ymm0, %ymm0
	vpmovmskb %ymm0, %ecx
	testl	%ecx, %ecx
	je	L(next_3_vectors)
	tzcntl	%ecx, %edx
# ifdef USE_AS_STRNCMP
	/* Return 0 if the mismatched index (%rdx) is after the maximum
	   offset (%r11).   */
	cmpq	%r11, %rdx
	jae	L(zero)
# endif
# ifdef USE_AS_WCSCMP
	xorl	%eax, %eax
	movl	(%rdi, %rdx), %ecx
	cmpl	(%rsi, %rdx), %ecx
	je	L(return)
L(wcscmp_return):
	setl	%al
	negl	%eax
	orl	$1, %eax
L(return):
# else
	movzbl	(%rdi, %rdx), %eax
	movzbl	(%rsi, %rdx), %edx
	subl	%edx, %eax
# endif
	VZEROUPPER
	ret

	.p2align 4
L(return_vec_size):
	tzcntl	%ecx, %edx
# ifdef USE_AS_STRNCMP
	/* Return 0 if the mismatched index (%rdx + VEC_SIZE) is after
	   the maximum offset (%r11).  */
	addq	$VEC_SIZE, %rdx
	cmpq	%r11, %rdx
	jae	L(zero)
#  ifdef USE_AS_WCSCMP
	xorl	%eax, %eax
	movl	(%rdi, %rdx), %ecx
	cmpl	(%rsi, %rdx), %ecx
	jne	L(wcscmp_return)
#  else
	movzbl	(%rdi, %rdx), %eax
	movzbl	(%rsi, %rdx), %edx
	subl	%edx, %eax
#  endif
# else
#  ifdef USE_AS_WCSCMP
	xorl	%eax, %eax
	movl	VEC_SIZE(%rdi, %rdx), %ecx
	cmpl	VEC_SIZE(%rsi, %rdx), %ecx
	jne	L(wcscmp_return)
#  else
	movzbl	VEC_SIZE(%rdi, %rdx), %eax
	movzbl	VEC_SIZE(%rsi, %rdx), %edx
	subl	%edx, %eax
#  endif
# endif
	VZEROUPPER
	ret

	.p2align 4
L(return_2_vec_size):
	tzcntl	%ecx, %edx
# ifdef USE_AS_STRNCMP
	/* Return 0 if the mismatched index (%rdx + 2 * VEC_SIZE) is
	   after the maximum offset (%r11).  */
	addq	$(VEC_SIZE * 2), %rdx
	cmpq	%r11, %rdx
	jae	L(zero)
#  ifdef USE_AS_WCSCMP
	xorl	%eax, %eax
	movl	(%rdi, %rdx), %ecx
	cmpl	(%rsi, %rdx), %ecx
	jne	L(wcscmp_return)
#  else
	movzbl	(%rdi, %rdx), %eax
	movzbl	(%rsi, %rdx), %edx
	subl	%edx, %eax
#  endif
# else
#  ifdef USE_AS_WCSCMP
	xorl	%eax, %eax
	movl	(VEC_SIZE * 2)(%rdi, %rdx), %ecx
	cmpl	(VEC_SIZE * 2)(%rsi, %rdx), %ecx
	jne	L(wcscmp_return)
#  else
	movzbl	(VEC_SIZE * 2)(%rdi, %rdx), %eax
	movzbl	(VEC_SIZE * 2)(%rsi, %rdx), %edx
	subl	%edx, %eax
#  endif
# endif
	VZEROUPPER
	ret

	.p2align 4
L(return_3_vec_size):
	tzcntl	%ecx, %edx
# ifdef USE_AS_STRNCMP
	/* Return 0 if the mismatched index (%rdx + 3 * VEC_SIZE) is
	   after the maximum offset (%r11).  */
	addq	$(VEC_SIZE * 3), %rdx
	cmpq	%r11, %rdx
	jae	L(zero)
#  ifdef USE_AS_WCSCMP
	xorl	%eax, %eax
	movl	(%rdi, %rdx), %ecx
	cmpl	(%rsi, %rdx), %ecx
	jne	L(wcscmp_return)
#  else
	movzbl	(%rdi, %rdx), %eax
	movzbl	(%rsi, %rdx), %edx
	subl	%edx, %eax
#  endif
# else
#  ifdef USE_AS_WCSCMP
	xorl	%eax, %eax
	movl	(VEC_SIZE * 3)(%rdi, %rdx), %ecx
	cmpl	(VEC_SIZE * 3)(%rsi, %rdx), %ecx
	jne	L(wcscmp_return)
#  else
	movzbl	(VEC_SIZE * 3)(%rdi, %rdx), %eax
	movzbl	(VEC_SIZE * 3)(%rsi, %rdx), %edx
	subl	%edx, %eax
#  endif
# endif
	VZEROUPPER
	ret

	.p2align 4
L(next_3_vectors):
	vmovdqu	VEC_SIZE(%rdi), %ymm6
	VPCMPEQ	VEC_SIZE(%rsi), %ymm6, %ymm3
	VPMINU	%ymm6, %ymm3, %ymm3
	VPCMPEQ	%ymm7, %ymm3, %ymm3
	vpmovmskb %ymm3, %ecx
	testl	%ecx, %ecx
	jne	L(return_vec_size)
	vmovdqu	(VEC_SIZE * 2)(%rdi), %ymm5
	vmovdqu	(VEC_SIZE * 3)(%rdi), %ymm4
	vmovdqu	(VEC_SIZE * 3)(%rsi), %ymm0
	VPCMPEQ	(VEC_SIZE * 2)(%rsi), %ymm5, %ymm2
	VPMINU	%ymm5, %ymm2, %ymm2
	VPCMPEQ	%ymm4, %ymm0, %ymm0
	VPCMPEQ	%ymm7, %ymm2, %ymm2
	vpmovmskb %ymm2, %ecx
	testl	%ecx, %ecx
	jne	L(return_2_vec_size)
	VPMINU	%ymm4, %ymm0, %ymm0
	VPCMPEQ	%ymm7, %ymm0, %ymm0
	vpmovmskb %ymm0, %ecx
	testl	%ecx, %ecx
	jne	L(return_3_vec_size)
L(main_loop_header):
	leaq	(VEC_SIZE * 4)(%rdi), %rdx
	movl	$PAGE_SIZE, %ecx
	/* Align load via RAX.  */
	andq	$-(VEC_SIZE * 4), %rdx
	subq	%rdi, %rdx
	leaq	(%rdi, %rdx), %rax
# ifdef USE_AS_STRNCMP
	/* Starting from this point, the maximum offset, or simply the
	   'offset', DECREASES by the same amount when base pointers are
	   moved forward.  Return 0 when:
	     1) On match: offset <= the matched vector index.
	     2) On mistmach, offset is before the mistmatched index.
	 */
	subq	%rdx, %r11
	jbe	L(zero)
# endif
	addq	%rsi, %rdx
	movq	%rdx, %rsi
	andl	$(PAGE_SIZE - 1), %esi
	/* Number of bytes before page crossing.  */
	subq	%rsi, %rcx
	/* Number of VEC_SIZE * 4 blocks before page crossing.  */
	shrq	$DIVIDE_BY_VEC_4_SHIFT, %rcx
	/* ESI: Number of VEC_SIZE * 4 blocks before page crossing.   */
	movl	%ecx, %esi
	jmp	L(loop_start)

	.p2align 4
L(loop):
# ifdef USE_AS_STRNCMP
	/* Base pointers are moved forward by 4 * VEC_SIZE.  Decrease
	   the maximum offset (%r11) by the same amount.  */
	subq	$(VEC_SIZE * 4), %r11
	jbe	L(zero)
# endif
	addq	$(VEC_SIZE * 4), %rax
	addq	$(VEC_SIZE * 4), %rdx
L(loop_start):
	testl	%esi, %esi
	leal	-1(%esi), %esi
	je	L(loop_cross_page)
L(back_to_loop):
	/* Main loop, comparing 4 vectors are a time.  */
	vmovdqa	(%rax), %ymm0
	vmovdqa	VEC_SIZE(%rax), %ymm3
	VPCMPEQ	(%rdx), %ymm0, %ymm4
	VPCMPEQ	VEC_SIZE(%rdx), %ymm3, %ymm1
	VPMINU	%ymm0, %ymm4, %ymm4
	VPMINU	%ymm3, %ymm1, %ymm1
	vmovdqa	(VEC_SIZE * 2)(%rax), %ymm2
	VPMINU	%ymm1, %ymm4, %ymm0
	vmovdqa	(VEC_SIZE * 3)(%rax), %ymm3
	VPCMPEQ	(VEC_SIZE * 2)(%rdx), %ymm2, %ymm5
	VPCMPEQ	(VEC_SIZE * 3)(%rdx), %ymm3, %ymm6
	VPMINU	%ymm2, %ymm5, %ymm5
	VPMINU	%ymm3, %ymm6, %ymm6
	VPMINU	%ymm5, %ymm0, %ymm0
	VPMINU	%ymm6, %ymm0, %ymm0
	VPCMPEQ	%ymm7, %ymm0, %ymm0

	/* Test each mask (32 bits) individually because for VEC_SIZE
	   == 32 is not possible to OR the four masks and keep all bits
	   in a 64-bit integer register, differing from SSE2 strcmp
	   where ORing is possible.  */
	vpmovmskb %ymm0, %ecx
	testl	%ecx, %ecx
	je	L(loop)
	VPCMPEQ	%ymm7, %ymm4, %ymm0
	vpmovmskb %ymm0, %edi
	testl	%edi, %edi
	je	L(test_vec)
	tzcntl	%edi, %ecx
# ifdef USE_AS_STRNCMP
	cmpq	%rcx, %r11
	jbe	L(zero)
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	(%rsi, %rcx), %edi
	cmpl	(%rdx, %rcx), %edi
	jne	L(wcscmp_return)
#  else
	movzbl	(%rax, %rcx), %eax
	movzbl	(%rdx, %rcx), %edx
	subl	%edx, %eax
#  endif
# else
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	(%rsi, %rcx), %edi
	cmpl	(%rdx, %rcx), %edi
	jne	L(wcscmp_return)
#  else
	movzbl	(%rax, %rcx), %eax
	movzbl	(%rdx, %rcx), %edx
	subl	%edx, %eax
#  endif
# endif
	VZEROUPPER
	ret

	.p2align 4
L(test_vec):
# ifdef USE_AS_STRNCMP
	/* The first vector matched.  Return 0 if the maximum offset
	   (%r11) <= VEC_SIZE.  */
	cmpq	$VEC_SIZE, %r11
	jbe	L(zero)
# endif
	VPCMPEQ	%ymm7, %ymm1, %ymm1
	vpmovmskb %ymm1, %ecx
	testl	%ecx, %ecx
	je	L(test_2_vec)
	tzcntl	%ecx, %edi
# ifdef USE_AS_STRNCMP
	addq	$VEC_SIZE, %rdi
	cmpq	%rdi, %r11
	jbe	L(zero)
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	(%rsi, %rdi), %ecx
	cmpl	(%rdx, %rdi), %ecx
	jne	L(wcscmp_return)
#  else
	movzbl	(%rax, %rdi), %eax
	movzbl	(%rdx, %rdi), %edx
	subl	%edx, %eax
#  endif
# else
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	VEC_SIZE(%rsi, %rdi), %ecx
	cmpl	VEC_SIZE(%rdx, %rdi), %ecx
	jne	L(wcscmp_return)
#  else
	movzbl	VEC_SIZE(%rax, %rdi), %eax
	movzbl	VEC_SIZE(%rdx, %rdi), %edx
	subl	%edx, %eax
#  endif
# endif
	VZEROUPPER
	ret

	.p2align 4
L(test_2_vec):
# ifdef USE_AS_STRNCMP
	/* The first 2 vectors matched.  Return 0 if the maximum offset
	   (%r11) <= 2 * VEC_SIZE.  */
	cmpq	$(VEC_SIZE * 2), %r11
	jbe	L(zero)
# endif
	VPCMPEQ	%ymm7, %ymm5, %ymm5
	vpmovmskb %ymm5, %ecx
	testl	%ecx, %ecx
	je	L(test_3_vec)
	tzcntl	%ecx, %edi
# ifdef USE_AS_STRNCMP
	addq	$(VEC_SIZE * 2), %rdi
	cmpq	%rdi, %r11
	jbe	L(zero)
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	(%rsi, %rdi), %ecx
	cmpl	(%rdx, %rdi), %ecx
	jne	L(wcscmp_return)
#  else
	movzbl	(%rax, %rdi), %eax
	movzbl	(%rdx, %rdi), %edx
	subl	%edx, %eax
#  endif
# else
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	(VEC_SIZE * 2)(%rsi, %rdi), %ecx
	cmpl	(VEC_SIZE * 2)(%rdx, %rdi), %ecx
	jne	L(wcscmp_return)
#  else
	movzbl	(VEC_SIZE * 2)(%rax, %rdi), %eax
	movzbl	(VEC_SIZE * 2)(%rdx, %rdi), %edx
	subl	%edx, %eax
#  endif
# endif
	VZEROUPPER
	ret

	.p2align 4
L(test_3_vec):
# ifdef USE_AS_STRNCMP
	/* The first 3 vectors matched.  Return 0 if the maximum offset
	   (%r11) <= 3 * VEC_SIZE.  */
	cmpq	$(VEC_SIZE * 3), %r11
	jbe	L(zero)
# endif
	VPCMPEQ	%ymm7, %ymm6, %ymm6
	vpmovmskb %ymm6, %esi
	tzcntl	%esi, %ecx
# ifdef USE_AS_STRNCMP
	addq	$(VEC_SIZE * 3), %rcx
	cmpq	%rcx, %r11
	jbe	L(zero)
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	(%rsi, %rcx), %esi
	cmpl	(%rdx, %rcx), %esi
	jne	L(wcscmp_return)
#  else
	movzbl	(%rax, %rcx), %eax
	movzbl	(%rdx, %rcx), %edx
	subl	%edx, %eax
#  endif
# else
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	(VEC_SIZE * 3)(%rsi, %rcx), %esi
	cmpl	(VEC_SIZE * 3)(%rdx, %rcx), %esi
	jne	L(wcscmp_return)
#  else
	movzbl	(VEC_SIZE * 3)(%rax, %rcx), %eax
	movzbl	(VEC_SIZE * 3)(%rdx, %rcx), %edx
	subl	%edx, %eax
#  endif
# endif
	VZEROUPPER
	ret

	.p2align 4
L(loop_cross_page):
	xorl	%r10d, %r10d
	movq	%rdx, %rcx
	/* Align load via RDX.  We load the extra ECX bytes which should
	   be ignored.  */
	andl	$((VEC_SIZE * 4) - 1), %ecx
	/* R10 is -RCX.  */
	subq	%rcx, %r10

	/* This works only if VEC_SIZE * 2 == 64. */
# if (VEC_SIZE * 2) != 64
#  error (VEC_SIZE * 2) != 64
# endif

	/* Check if the first VEC_SIZE * 2 bytes should be ignored.  */
	cmpl	$(VEC_SIZE * 2), %ecx
	jge	L(loop_cross_page_2_vec)

	vmovdqu	(%rax, %r10), %ymm2
	vmovdqu	VEC_SIZE(%rax, %r10), %ymm3
	VPCMPEQ	(%rdx, %r10), %ymm2, %ymm0
	VPCMPEQ	VEC_SIZE(%rdx, %r10), %ymm3, %ymm1
	VPMINU	%ymm2, %ymm0, %ymm0
	VPMINU	%ymm3, %ymm1, %ymm1
	VPCMPEQ	%ymm7, %ymm0, %ymm0
	VPCMPEQ	%ymm7, %ymm1, %ymm1

	vpmovmskb %ymm0, %edi
	vpmovmskb %ymm1, %esi

	salq	$32, %rsi
	xorq	%rsi, %rdi

	/* Since ECX < VEC_SIZE * 2, simply skip the first ECX bytes.  */
	shrq	%cl, %rdi

	testq	%rdi, %rdi
	je	L(loop_cross_page_2_vec)
	tzcntq	%rdi, %rcx
# ifdef USE_AS_STRNCMP
	cmpq	%rcx, %r11
	jbe	L(zero)
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	(%rsi, %rcx), %edi
	cmpl	(%rdx, %rcx), %edi
	jne	L(wcscmp_return)
#  else
	movzbl	(%rax, %rcx), %eax
	movzbl	(%rdx, %rcx), %edx
	subl	%edx, %eax
#  endif
# else
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	(%rsi, %rcx), %edi
	cmpl	(%rdx, %rcx), %edi
	jne	L(wcscmp_return)
#  else
	movzbl	(%rax, %rcx), %eax
	movzbl	(%rdx, %rcx), %edx
	subl	%edx, %eax
#  endif
# endif
	VZEROUPPER
	ret

	.p2align 4
L(loop_cross_page_2_vec):
	/* The first VEC_SIZE * 2 bytes match or are ignored.  */
	vmovdqu	(VEC_SIZE * 2)(%rax, %r10), %ymm2
	vmovdqu	(VEC_SIZE * 3)(%rax, %r10), %ymm3
	VPCMPEQ	(VEC_SIZE * 2)(%rdx, %r10), %ymm2, %ymm5
	VPMINU	%ymm2, %ymm5, %ymm5
	VPCMPEQ	(VEC_SIZE * 3)(%rdx, %r10), %ymm3, %ymm6
	VPCMPEQ	%ymm7, %ymm5, %ymm5
	VPMINU	%ymm3, %ymm6, %ymm6
	VPCMPEQ	%ymm7, %ymm6, %ymm6

	vpmovmskb %ymm5, %edi
	vpmovmskb %ymm6, %esi

	salq	$32, %rsi
	xorq	%rsi, %rdi

	xorl	%r8d, %r8d
	/* If ECX > VEC_SIZE * 2, skip ECX - (VEC_SIZE * 2) bytes.  */
	subl	$(VEC_SIZE * 2), %ecx
	jle	1f
	/* Skip ECX bytes.  */
	shrq	%cl, %rdi
	/* R8 has number of bytes skipped.  */
	movl	%ecx, %r8d
1:
	/* Before jumping back to the loop, set ESI to the number of
	   VEC_SIZE * 4 blocks before page crossing.  */
	movl	$(PAGE_SIZE / (VEC_SIZE * 4) - 1), %esi

	testq	%rdi, %rdi
	je	L(back_to_loop)
	tzcntq	%rdi, %rcx
	addq	%r10, %rcx
	/* Adjust for number of bytes skipped.  */
	addq	%r8, %rcx
# ifdef USE_AS_STRNCMP
	addq	$(VEC_SIZE * 2), %rcx
	subq	%rcx, %r11
	jbe	L(zero)
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	(%rsi, %rcx), %edi
	cmpl	(%rdx, %rcx), %edi
	jne	L(wcscmp_return)
#  else
	movzbl	(%rax, %rcx), %eax
	movzbl	(%rdx, %rcx), %edx
	subl	%edx, %eax
#  endif
# else
#  ifdef USE_AS_WCSCMP
	movq	%rax, %rsi
	xorl	%eax, %eax
	movl	(VEC_SIZE * 2)(%rsi, %rcx), %edi
	cmpl	(VEC_SIZE * 2)(%rdx, %rcx), %edi
	jne	L(wcscmp_return)
#  else
	movzbl	(VEC_SIZE * 2)(%rax, %rcx), %eax
	movzbl	(VEC_SIZE * 2)(%rdx, %rcx), %edx
	subl	%edx, %eax
#  endif
# endif
	VZEROUPPER
	ret

	.p2align 4
L(cross_page_loop):
	/* Check one byte/dword at a time.  */
# ifdef USE_AS_WCSCMP
	cmpl	%ecx, %eax
# else
	subl	%ecx, %eax
# endif
	jne	L(different)
	addl	$SIZE_OF_CHAR, %edx
	cmpl	$(VEC_SIZE * 4), %edx
	je	L(main_loop_header)
# ifdef USE_AS_STRNCMP
	cmpq	%r11, %rdx
	jae	L(zero)
# endif
# ifdef USE_AS_WCSCMP
	movl	(%rdi, %rdx), %eax
	movl	(%rsi, %rdx), %ecx
# else
	movzbl	(%rdi, %rdx), %eax
	movzbl	(%rsi, %rdx), %ecx
# endif
	/* Check null char.  */
	testl	%eax, %eax
	jne	L(cross_page_loop)
	/* Since %eax == 0, subtract is OK for both SIGNED and UNSIGNED
	   comparisons.  */
	subl	%ecx, %eax
# ifndef USE_AS_WCSCMP
L(different):
# endif
	VZEROUPPER
	ret

# ifdef USE_AS_WCSCMP
	.p2align 4
L(different):
	/* Use movl to avoid modifying EFLAGS.  */
	movl	$0, %eax
	setl	%al
	negl	%eax
	orl	$1, %eax
	VZEROUPPER
	ret
# endif

# ifdef USE_AS_STRNCMP
	.p2align 4
L(zero):
	xorl	%eax, %eax
	VZEROUPPER
	ret

	.p2align 4
L(char0):
#  ifdef USE_AS_WCSCMP
	xorl	%eax, %eax
	movl	(%rdi), %ecx
	cmpl	(%rsi), %ecx
	jne	L(wcscmp_return)
#  else
	movzbl	(%rsi), %ecx
	movzbl	(%rdi), %eax
	subl	%ecx, %eax
#  endif
	VZEROUPPER
	ret
# endif

	.p2align 4
L(last_vector):
	addq	%rdx, %rdi
	addq	%rdx, %rsi
# ifdef USE_AS_STRNCMP
	subq	%rdx, %r11
# endif
	tzcntl	%ecx, %edx
# ifdef USE_AS_STRNCMP
	cmpq	%r11, %rdx
	jae	L(zero)
# endif
# ifdef USE_AS_WCSCMP
	xorl	%eax, %eax
	movl	(%rdi, %rdx), %ecx
	cmpl	(%rsi, %rdx), %ecx
	jne	L(wcscmp_return)
# else
	movzbl	(%rdi, %rdx), %eax
	movzbl	(%rsi, %rdx), %edx
	subl	%edx, %eax
# endif
	VZEROUPPER
	ret

	/* Comparing on page boundary region requires special treatment:
	   It must done one vector at the time, starting with the wider
	   ymm vector if possible, if not, with xmm. If fetching 16 bytes
	   (xmm) still passes the boundary, byte comparison must be done.
	 */
	.p2align 4
L(cross_page):
	/* Try one ymm vector at a time.  */
	cmpl	$(PAGE_SIZE - VEC_SIZE), %eax
	jg	L(cross_page_1_vector)
L(loop_1_vector):
	vmovdqu	(%rdi, %rdx), %ymm1
	VPCMPEQ	(%rsi, %rdx), %ymm1, %ymm0
	VPMINU	%ymm1, %ymm0, %ymm0
	VPCMPEQ	%ymm7, %ymm0, %ymm0
	vpmovmskb %ymm0, %ecx
	testl	%ecx, %ecx
	jne	L(last_vector)

	addl	$VEC_SIZE, %edx

	addl	$VEC_SIZE, %eax
# ifdef USE_AS_STRNCMP
	/* Return 0 if the current offset (%rdx) >= the maximum offset
	   (%r11).  */
	cmpq	%r11, %rdx
	jae	L(zero)
# endif
	cmpl	$(PAGE_SIZE - VEC_SIZE), %eax
	jle	L(loop_1_vector)
L(cross_page_1_vector):
	/* Less than 32 bytes to check, try one xmm vector.  */
	cmpl	$(PAGE_SIZE - 16), %eax
	jg	L(cross_page_1_xmm)
	vmovdqu	(%rdi, %rdx), %xmm1
	VPCMPEQ	(%rsi, %rdx), %xmm1, %xmm0
	VPMINU	%xmm1, %xmm0, %xmm0
	VPCMPEQ	%xmm7, %xmm0, %xmm0
	vpmovmskb %xmm0, %ecx
	testl	%ecx, %ecx
	jne	L(last_vector)

	addl	$16, %edx
# ifndef USE_AS_WCSCMP
	addl	$16, %eax
# endif
# ifdef USE_AS_STRNCMP
	/* Return 0 if the current offset (%rdx) >= the maximum offset
	   (%r11).  */
	cmpq	%r11, %rdx
	jae	L(zero)
# endif

L(cross_page_1_xmm):
# ifndef USE_AS_WCSCMP
	/* Less than 16 bytes to check, try 8 byte vector.  NB: No need
	   for wcscmp nor wcsncmp since wide char is 4 bytes.   */
	cmpl	$(PAGE_SIZE - 8), %eax
	jg	L(cross_page_8bytes)
	vmovq	(%rdi, %rdx), %xmm1
	vmovq	(%rsi, %rdx), %xmm0
	VPCMPEQ	%xmm0, %xmm1, %xmm0
	VPMINU	%xmm1, %xmm0, %xmm0
	VPCMPEQ	%xmm7, %xmm0, %xmm0
	vpmovmskb %xmm0, %ecx
	/* Only last 8 bits are valid.  */
	andl	$0xff, %ecx
	testl	%ecx, %ecx
	jne	L(last_vector)

	addl	$8, %edx
	addl	$8, %eax
#  ifdef USE_AS_STRNCMP
	/* Return 0 if the current offset (%rdx) >= the maximum offset
	   (%r11).  */
	cmpq	%r11, %rdx
	jae	L(zero)
#  endif

L(cross_page_8bytes):
	/* Less than 8 bytes to check, try 4 byte vector.  */
	cmpl	$(PAGE_SIZE - 4), %eax
	jg	L(cross_page_4bytes)
	vmovd	(%rdi, %rdx), %xmm1
	vmovd	(%rsi, %rdx), %xmm0
	VPCMPEQ	%xmm0, %xmm1, %xmm0
	VPMINU	%xmm1, %xmm0, %xmm0
	VPCMPEQ	%xmm7, %xmm0, %xmm0
	vpmovmskb %xmm0, %ecx
	/* Only last 4 bits are valid.  */
	andl	$0xf, %ecx
	testl	%ecx, %ecx
	jne	L(last_vector)

	addl	$4, %edx
#  ifdef USE_AS_STRNCMP
	/* Return 0 if the current offset (%rdx) >= the maximum offset
	   (%r11).  */
	cmpq	%r11, %rdx
	jae	L(zero)
#  endif

L(cross_page_4bytes):
# endif
	/* Less than 4 bytes to check, try one byte/dword at a time.  */
# ifdef USE_AS_STRNCMP
	cmpq	%r11, %rdx
	jae	L(zero)
# endif
# ifdef USE_AS_WCSCMP
	movl	(%rdi, %rdx), %eax
	movl	(%rsi, %rdx), %ecx
# else
	movzbl	(%rdi, %rdx), %eax
	movzbl	(%rsi, %rdx), %ecx
# endif
	testl	%eax, %eax
	jne	L(cross_page_loop)
	subl	%ecx, %eax
	VZEROUPPER
	ret
END (STRCMP)
#endif