aboutsummaryrefslogtreecommitdiff
path: root/sysdeps/tile/memcmp.c
blob: 7ce924754685b775eb0d01d8f90bc32402aabe57 (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
/* Copyright (C) 1991-2015 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 HAVE_CONFIG_H
# include "config.h"
#endif

#undef	__ptr_t
#define __ptr_t	void *

#if defined HAVE_STRING_H || defined _LIBC
# include <string.h>
#endif

#undef memcmp

#ifndef MEMCMP
# define MEMCMP memcmp
#endif

#ifdef _LIBC

# include <memcopy.h>
# include <endian.h>

# if __BYTE_ORDER == __BIG_ENDIAN
#  define WORDS_BIGENDIAN
# endif

#else	/* Not in the GNU C library.  */

# include <sys/types.h>

/* Type to use for aligned memory operations.
   This should normally be the biggest type supported by a single load
   and store.  Must be an unsigned type.  */
# define op_t	unsigned long int
# define OPSIZ	(sizeof(op_t))

/* Threshold value for when to enter the unrolled loops.  */
# define OP_T_THRES	16

/* Type to use for unaligned operations.  */
typedef unsigned char byte;

#endif	/* In the GNU C library.  */

/* Provide the appropriate builtins to shift two registers based on
   the alignment of a pointer held in a third register, and to reverse
   the bytes in a word.  */
#ifdef __tilegx__
#define DBLALIGN __insn_dblalign
#define REVBYTES __insn_revbytes
#else
#define DBLALIGN __insn_dword_align
#define REVBYTES __insn_bytex
#endif

#ifdef WORDS_BIGENDIAN
# define CMP_LT_OR_GT(a, b) ((a) > (b) ? 1 : -1)
#else
# define CMP_LT_OR_GT(a, b) (REVBYTES(a) > REVBYTES(b) ? 1 : -1)
#endif

/* BE VERY CAREFUL IF YOU CHANGE THIS CODE!  */

/* The strategy of this memcmp is:

   1. Compare bytes until one of the block pointers is aligned.

   2. Compare using memcmp_common_alignment or
      memcmp_not_common_alignment, regarding the alignment of the other
      block after the initial byte operations.  The maximum number of
      full words (of type op_t) are compared in this way.

   3. Compare the few remaining bytes.  */

static int memcmp_common_alignment (long, long, size_t) __THROW;

/* memcmp_common_alignment -- Compare blocks at SRCP1 and SRCP2 with LEN `op_t'
   objects (not LEN bytes!).  Both SRCP1 and SRCP2 should be aligned for
   memory operations on `op_t's.  */
static int
memcmp_common_alignment (srcp1, srcp2, len)
     long int srcp1;
     long int srcp2;
     size_t len;
{
  op_t a0, a1;
  op_t b0, b1;

  switch (len % 4)
    {
    default: /* Avoid warning about uninitialized local variables.  */
    case 2:
      a0 = ((op_t *) srcp1)[0];
      b0 = ((op_t *) srcp2)[0];
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      len += 2;
      goto do1;
    case 3:
      a1 = ((op_t *) srcp1)[0];
      b1 = ((op_t *) srcp2)[0];
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      len += 1;
      goto do2;
    case 0:
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	return 0;
      a0 = ((op_t *) srcp1)[0];
      b0 = ((op_t *) srcp2)[0];
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      goto do3;
    case 1:
      a1 = ((op_t *) srcp1)[0];
      b1 = ((op_t *) srcp2)[0];
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      len -= 1;
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	goto do0;
      /* Fall through.  */
    }

  do
    {
      a0 = ((op_t *) srcp1)[0];
      b0 = ((op_t *) srcp2)[0];
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      if (__glibc_likely (a1 != b1))
	return CMP_LT_OR_GT (a1, b1);

    do3:
      a1 = ((op_t *) srcp1)[0];
      b1 = ((op_t *) srcp2)[0];
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      if (__glibc_likely (a0 != b0))
	return CMP_LT_OR_GT (a0, b0);

    do2:
      a0 = ((op_t *) srcp1)[0];
      b0 = ((op_t *) srcp2)[0];
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      if (__glibc_likely (a1 != b1))
	return CMP_LT_OR_GT (a1, b1);

    do1:
      a1 = ((op_t *) srcp1)[0];
      b1 = ((op_t *) srcp2)[0];
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      if (__glibc_likely (a0 != b0))
	return CMP_LT_OR_GT (a0, b0);

      len -= 4;
    }
  while (len != 0);

  /* This is the right position for do0.  Please don't move
     it into the loop.  */
 do0:
  if (__glibc_likely (a1 != b1))
    return CMP_LT_OR_GT (a1, b1);
  return 0;
}

static int memcmp_not_common_alignment (long, long, size_t) __THROW;

/* memcmp_not_common_alignment -- Compare blocks at SRCP1 and SRCP2 with LEN
   `op_t' objects (not LEN bytes!).  SRCP2 should be aligned for memory
   operations on `op_t', but SRCP1 *should be unaligned*.  */
static int
memcmp_not_common_alignment (srcp1, srcp2, len)
     long int srcp1;
     long int srcp2;
     size_t len;
{
  void * srcp1i;
  op_t a0, a1, a2, a3;
  op_t b0, b1, b2, b3;
  op_t x;

  /* Calculate how to shift a word read at the memory operation
     aligned srcp1 to make it aligned for comparison.  */

  srcp1i = (void *) srcp1;

  /* Make SRCP1 aligned by rounding it down to the beginning of the `op_t'
     it points in the middle of.  */
  srcp1 &= -OPSIZ;

  switch (len % 4)
    {
    default: /* Avoid warning about uninitialized local variables.  */
    case 2:
      a1 = ((op_t *) srcp1)[0];
      a2 = ((op_t *) srcp1)[1];
      b2 = ((op_t *) srcp2)[0];
      srcp1 += 2 * OPSIZ;
      srcp2 += 1 * OPSIZ;
      len += 2;
      goto do1;
    case 3:
      a0 = ((op_t *) srcp1)[0];
      a1 = ((op_t *) srcp1)[1];
      b1 = ((op_t *) srcp2)[0];
      srcp1 += 2 * OPSIZ;
      srcp2 += 1 * OPSIZ;
      len += 1;
      goto do2;
    case 0:
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	return 0;
      a3 = ((op_t *) srcp1)[0];
      a0 = ((op_t *) srcp1)[1];
      b0 = ((op_t *) srcp2)[0];
      srcp1 += 2 * OPSIZ;
      srcp2 += 1 * OPSIZ;
      goto do3;
    case 1:
      a2 = ((op_t *) srcp1)[0];
      a3 = ((op_t *) srcp1)[1];
      b3 = ((op_t *) srcp2)[0];
      srcp1 += 2 * OPSIZ;
      srcp2 += 1 * OPSIZ;
      len -= 1;
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	goto do0;
      /* Fall through.  */
    }

  do
    {
      a0 = ((op_t *) srcp1)[0];
      b0 = ((op_t *) srcp2)[0];
      x = DBLALIGN (a2, a3, srcp1i);
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      if (__glibc_likely (x != b3))
	return CMP_LT_OR_GT (x, b3);

    do3:
      a1 = ((op_t *) srcp1)[0];
      b1 = ((op_t *) srcp2)[0];
      x = DBLALIGN (a3, a0, srcp1i);
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      if (__glibc_likely (x != b0))
	return CMP_LT_OR_GT (x, b0);

    do2:
      a2 = ((op_t *) srcp1)[0];
      b2 = ((op_t *) srcp2)[0];
      x = DBLALIGN (a0, a1, srcp1i);
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      if (__glibc_likely (x != b1))
	return CMP_LT_OR_GT (x, b1);

    do1:
      a3 = ((op_t *) srcp1)[0];
      b3 = ((op_t *) srcp2)[0];
      x = DBLALIGN (a1, a2, srcp1i);
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      if (__glibc_likely (x != b2))
	return CMP_LT_OR_GT (x, b2);

      len -= 4;
    }
  while (len != 0);

  /* This is the right position for do0.  Please don't move
     it into the loop.  */
 do0:
  x = DBLALIGN (a2, a3, srcp1i);
  if (__glibc_likely (x != b3))
    return CMP_LT_OR_GT (x, b3);
  return 0;
}

int
MEMCMP (s1, s2, len)
     const __ptr_t s1;
     const __ptr_t s2;
     size_t len;
{
  op_t a0;
  op_t b0;
  long int srcp1 = (long int) s1;
  long int srcp2 = (long int) s2;
  int res;

  if (len >= OP_T_THRES)
    {
      /* There are at least some bytes to compare.  No need to test
	 for LEN == 0 in this alignment loop.  */
      while (srcp2 % OPSIZ != 0)
	{
	  a0 = ((byte *) srcp1)[0];
	  b0 = ((byte *) srcp2)[0];
	  srcp1 += 1;
	  srcp2 += 1;
	  res = a0 - b0;
	  if (__glibc_likely (res != 0))
	    return res;
	  len -= 1;
	}

      /* SRCP2 is now aligned for memory operations on `op_t'.
	 SRCP1 alignment determines if we can do a simple,
	 aligned compare or need to shuffle bits.  */

      if (srcp1 % OPSIZ == 0)
	res = memcmp_common_alignment (srcp1, srcp2, len / OPSIZ);
      else
	res = memcmp_not_common_alignment (srcp1, srcp2, len / OPSIZ);
      if (res != 0)
	return res;

      /* Number of bytes remaining in the interval [0..OPSIZ-1].  */
      srcp1 += len & -OPSIZ;
      srcp2 += len & -OPSIZ;
      len %= OPSIZ;
    }

  /* There are just a few bytes to compare.  Use byte memory operations.  */
  while (len != 0)
    {
      a0 = ((byte *) srcp1)[0];
      b0 = ((byte *) srcp2)[0];
      srcp1 += 1;
      srcp2 += 1;
      res = a0 - b0;
      if (__glibc_likely (res != 0))
	return res;
      len -= 1;
    }

  return 0;
}
libc_hidden_builtin_def(memcmp)
#ifdef weak_alias
# undef bcmp
weak_alias (memcmp, bcmp)
#endif