about summary refs log tree commit diff
path: root/sysdeps/powerpc/powerpc64/power9/strncmp.S
blob: ff6f8aceebf3c592bd5916f2902eaa7136b3b792 (plain) (blame)
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
/* Optimized strncmp implementation for PowerPC64/POWER9.
   Copyright (C) 2016-2017 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/>.  */
#ifdef __LITTLE_ENDIAN__
#include <sysdep.h>

/* Implements the function

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

   The implementation uses unaligned doubleword access to avoid specialized
   code paths depending of data alignment for first 32 bytes and uses
   vectorised loops after that.  */

#ifndef STRNCMP
# define STRNCMP strncmp
#endif

/* TODO: Change this to actual instructions when minimum binutils is upgraded
   to 2.27. Macros are defined below for these newer instructions in order
   to maintain compatibility.  */
# define VCTZLSBB(r,v) .long (0x10010602 | ((r)<<(32-11)) | ((v)<<(32-21)))

# define VEXTUBRX(t,a,b) .long (0x1000070d \
				| ((t)<<(32-11))  \
				| ((a)<<(32-16))  \
				| ((b)<<(32-21)) )

# define VCMPNEZB(t,a,b) .long (0x10000507 \
				| ((t)<<(32-11))  \
				| ((a)<<(32-16))  \
				| ((b)<<(32-21)) )

/* Get 16 bytes for unaligned case.
   reg1: Vector to hold next 16 bytes.
   reg2: Address to read from.
   reg3: Permute control vector.  */
# define GET16BYTES(reg1, reg2, reg3) \
	lvx	reg1, 0, reg2; \
	vperm	v8, v2, reg1, reg3; \
	vcmpequb.	v8, v0, v8; \
	beq	cr6, 1f; \
	vspltisb	v9, 0; \
	b	2f; \
	.align 4; \
1: \
	cmplw	cr6, r5, r11; \
	ble	cr6, 2f; \
	addi	r6, reg2, 16; \
	lvx	v9, 0, r6; \
2: \
	vperm	reg1, v9, reg1, reg3;

/* TODO: change this to .machine power9 when minimum binutils
   is upgraded to 2.27.  */
	.machine  power7
ENTRY_TOCLESS (STRNCMP, 4)
	/* Check if size is 0.  */
	cmpdi	cr0, r5, 0
	beq	cr0, L(ret0)
	li	r0, 0

	/* Check if [s1]+32 or [s2]+32 will cross a 4K page boundary using
	   the code:

	    (((size_t) s1) % PAGE_SIZE > (PAGE_SIZE - ITER_SIZE))

	   with PAGE_SIZE being 4096 and ITER_SIZE begin 32.  */
	rldicl	r8, r3, 0, 52
	cmpldi	cr7, r8, 4096-32
	bgt	cr7, L(pagecross)
	rldicl	r9, r4, 0, 52
	cmpldi	cr7, r9, 4096-32
	bgt	cr7, L(pagecross)

	/* For short strings up to 32 bytes, load both s1 and s2 using
	   unaligned dwords and compare.  */

	ld	r7, 0(r3)
	ld	r9, 0(r4)
	li	r8, 0
	cmpb	r8, r7, r8
	cmpb	r6, r7, r9
	orc.	r8, r8, r6
	bne	cr0, L(different1)

	/* If the strings compared are equal, but size is less or equal
	   to 8, return 0.  */
	cmpldi	cr7, r5, 8
	li	r9, 0
	ble	cr7, L(ret1)
	addi	r5, r5, -8

	ld	r7, 8(r3)
	ld	r9, 8(r4)
	cmpb	r8, r7, r8
	cmpb	r6, r7, r9
	orc.	r8, r8, r6
	bne	cr0, L(different1)
	cmpldi	cr7, r5, 8
	mr	r9, r8
	ble	cr7, L(ret1)
	/* Update pointers and size.  */
	addi	r5, r5, -8
	addi	r3, r3, 16
	addi	r4, r4, 16

	ld	r7, 0(r3)
	ld	r9, 0(r4)
	li	r8, 0
	cmpb	r8, r7, r8
	cmpb	r6, r7, r9
	orc.	r8, r8, r6
	bne	cr0, L(different1)
	cmpldi	cr7, r5, 8
	li	r9, 0
	ble	cr7, L(ret1)
	addi	r5, r5, -8

	ld	r7, 8(r3)
	ld	r9, 8(r4)
	cmpb	r8, r7, r8
	cmpb	r6, r7, r9
	orc.	r8, r8, r6
	bne	cr0, L(different1)
	cmpldi	cr7, r5, 8
	mr	r9, r8
	ble	cr7, L(ret1)

	/* Update pointers and size.  */
	addi	r5, r5, -8
	addi	r3, r3, 16
	addi	r4, r4, 16
L(align):
	/* Now it has checked for first 32 bytes, align source1 to doubleword
	   and adjust source2 address.  */
	vspltisb	v0, 0
	vspltisb	v2, -1
	or	r6, r4, r3
	andi.	r6, r6, 0xF
	beq	cr0, L(aligned)
	lvsr	v6, 0, r4   /* Compute mask.  */
	clrldi	r6, r4, 60
	subfic	r11, r6, 16
	andi.	r6, r3, 0xF
	beq	cr0, L(s1_align)
	/* Both s1 and s2 are unaligned.  */
	GET16BYTES(v5, r4, v6)
	lvsr	v10, 0, r3   /* Compute mask.  */
	clrldi	r6, r3, 60
	subfic	r11, r6, 16
	GET16BYTES(v4, r3, v10)
	VCMPNEZB(v7, v5, v4)
	beq	cr6, L(match)
	b	L(different)

	/* Align s1 to qw and adjust s2 address.  */
	.align  4
L(match):
	cmpldi	cr7, r5, 16
	ble	cr7, L(ret0)
	subf	r5, r11, r5
	add	r3, r3, r11
	add	r4, r4, r11
	andi.	r11, r4, 0xF
	beq	cr0, L(aligned)
	lvsr	v6, 0, r4
	clrldi	r6, r4, 60
	subfic	r11, r6, 16
	/* There are 2 loops depending on the input alignment.
	   Each loop gets 16 bytes from s1 and s2, checks for null
	   and compares them. Loops until a mismatch or  null occurs.  */
L(s1_align):
	lvx	v4, 0, r3
	GET16BYTES(v5, r4, v6)
	VCMPNEZB(v7, v5, v4)
	bne	cr6, L(different)
	cmpldi	cr7, r5, 16
	ble	cr7, L(ret0)
	addi	r5, r5, -16
	addi	r3, r3, 16
	addi	r4, r4, 16

	lvx	v4, 0, r3
	GET16BYTES(v5, r4, v6)
	VCMPNEZB(v7, v5, v4)
	bne	cr6, L(different)
	cmpldi	cr7, r5, 16
	ble	cr7, L(ret0)
	addi	r5, r5, -16
	addi	r3, r3, 16
	addi	r4, r4, 16

	lvx	v4, 0, r3
	GET16BYTES(v5, r4, v6)
	VCMPNEZB(v7, v5, v4)
	bne	cr6, L(different)
	cmpldi	cr7, r5, 16
	ble	cr7, L(ret0)
	addi	r5, r5, -16
	addi	r3, r3, 16
	addi	r4, r4, 16

	lvx	v4, 0, r3
	GET16BYTES(v5, r4, v6)
	VCMPNEZB(v7, v5, v4)
	bne	cr6, L(different)
	cmpldi	cr7, r5, 16
	ble	cr7, L(ret0)
	addi	r5, r5, -16
	addi	r3, r3, 16
	addi	r4, r4, 16
	b	L(s1_align)
	.align  4
L(aligned):
	lvx	v4, 0, r3
	lvx	v5, 0, r4
	VCMPNEZB(v7, v5, v4)
	bne	cr6, L(different)
	cmpldi	cr7, r5, 16
	ble	cr7, L(ret0)
	addi	r5, r5, -16
	addi	r3, r3, 16
	addi	r4, r4, 16

	lvx	v4, 0, r3
	lvx	v5, 0, r4
	VCMPNEZB(v7, v5, v4)
	bne	cr6, L(different)
	cmpldi	cr7, r5, 16
	ble	cr7, L(ret0)
	addi	r5, r5, -16
	addi	r3, r3, 16
	addi	r4, r4, 16

	lvx	v4, 0, r3
	lvx	v5, 0, r4
	VCMPNEZB(v7, v5, v4)
	bne	cr6, L(different)
	cmpldi	cr7, r5, 16
	ble	cr7, L(ret0)
	addi	r5, r5, -16
	addi	r3, r3, 16
	addi	r4, r4, 16

	lvx	v4, 0, r3
	lvx	v5, 0, r4
	VCMPNEZB(v7, v5, v4)
	bne	cr6, L(different)
	cmpldi	cr7, r5, 16
	ble	cr7, L(ret0)
	addi	r5, r5, -16
	addi	r3, r3, 16
	addi	r4, r4, 16
	b	L(aligned)
	/* Calculate and return the difference.  */
L(different):
	VCTZLSBB(r6, v7)
	cmplw	cr7, r5, r6
	ble	cr7, L(ret0)
	VEXTUBRX(r5, r6, v4)
	VEXTUBRX(r4, r6, v5)
	subf	r3, r4, r5
	extsw	r3, r3
	blr

	.align 4
L(ret0):
	li	r9, 0
L(ret1):
	mr	r3, r9
	blr

	/* The code now checks if r8 and r5 are different by issuing a
	   cmpb and shifts the result based on its output:

	  leadzero = (__builtin_ffsl (z1) - 1);
	  leadzero = leadzero > (n-1)*8 ? (n-1)*8 : leadzero;
	  r1 = (r1 >> leadzero) & 0xFFUL;
	  r2 = (r2 >> leadzero) & 0xFFUL;
	  return r1 - r2;  */

	.align 4
L(different1):
	neg	r11, r8
	sldi	r5, r5, 3
	and	r8, r11, r8
	addi	r5, r5, -8
	cntlzd	r8, r8
	subfic	r8, r8, 63
	extsw 	r8, r8
	cmpld	cr7, r8, r5
	ble	cr7, L(different2)
	mr	r8, r5
L(different2):
	extsw	r8, r8
	srd	r7, r7, r8
	srd	r9, r9, r8
	rldicl	r3, r7, 0, 56
	rldicl	r9, r9, 0, 56
	subf	r9, r9, 3
	extsw	r9, r9
	mr	r3, r9
	blr

	/* If unaligned 16 bytes reads across a 4K page boundary, it uses
	   a simple byte a byte comparison until the page alignment for s1
	   is reached.  */
	.align 4
L(pagecross):
	lbz	r7, 0(r3)
	lbz	r9, 0(r4)
	subfic	r8, r8,4095
	cmplw	cr7, r9, r7
	bne	cr7, L(byte_ne_3)
	cmpdi	cr7, r9, 0
	beq	cr7, L(byte_ne_0)
	addi	r5, r5, -1
	subf	r7, r8, r5
	subf	r9, r7, r5
	addi	r9, r9, 1
	mtctr	r9
	b	L(pagecross_loop1)

	.align 4
L(pagecross_loop0):
	beq	cr7, L(ret0)
	lbz	r9, 0(r3)
	lbz	r8, 0(r4)
	addi	r5, r5, -1
	cmplw	cr7, r9, r8
	cmpdi	cr5, r9, 0
	bne	cr7, L(byte_ne_2)
	beq	cr5, L(byte_ne_0)
L(pagecross_loop1):
	cmpdi	cr7, r5, 0
	addi	r3, r3, 1
	addi	r4, r4, 1
	bdnz	L(pagecross_loop0)
	cmpdi	cr7, r7, 0
	li	r9, 0
	bne+	cr7, L(align)
	b	L(ret1)

	.align 4
L(byte_ne_0):
	li	r7, 0
L(byte_ne_1):
	subf	r9, r9, r7
	extsw	r9, r9
	b	L(ret1)

	.align 4
L(byte_ne_2):
	extsw	r7, r9
	mr	r9, r8
	b	L(byte_ne_1)
L(byte_ne_3):
	extsw	r7, r7
	b	L(byte_ne_1)
END(STRNCMP)
libc_hidden_builtin_def(strncmp)
#else
#include <sysdeps/powerpc/powerpc64/power8/strncmp.S>
#endif