8fe7ab828b40ec0df914c526c1607ca9c444f470
[gcc.git] / gcc / config / i386 / driver-i386.c
1 /* Subroutines for the gcc driver.
2 Copyright (C) 2006, 2007, 2008, 2010 Free Software Foundation, Inc.
3
4 This file is part of GCC.
5
6 GCC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
9 any later version.
10
11 GCC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
19
20 #include "config.h"
21 #include "system.h"
22 #include "coretypes.h"
23 #include "tm.h"
24
25 const char *host_detect_local_cpu (int argc, const char **argv);
26
27 #ifdef __GNUC__
28 #include "cpuid.h"
29
30 struct cache_desc
31 {
32 unsigned sizekb;
33 unsigned assoc;
34 unsigned line;
35 };
36
37 /* Returns command line parameters that describe size and
38 cache line size of the processor caches. */
39
40 static char *
41 describe_cache (struct cache_desc level1, struct cache_desc level2)
42 {
43 char size[100], line[100], size2[100];
44
45 /* At the moment, gcc does not use the information
46 about the associativity of the cache. */
47
48 snprintf (size, sizeof (size),
49 "--param l1-cache-size=%u ", level1.sizekb);
50 snprintf (line, sizeof (line),
51 "--param l1-cache-line-size=%u ", level1.line);
52
53 snprintf (size2, sizeof (size2),
54 "--param l2-cache-size=%u ", level2.sizekb);
55
56 return concat (size, line, size2, NULL);
57 }
58
59 /* Detect L2 cache parameters using CPUID extended function 0x80000006. */
60
61 static void
62 detect_l2_cache (struct cache_desc *level2)
63 {
64 unsigned eax, ebx, ecx, edx;
65 unsigned assoc;
66
67 __cpuid (0x80000006, eax, ebx, ecx, edx);
68
69 level2->sizekb = (ecx >> 16) & 0xffff;
70 level2->line = ecx & 0xff;
71
72 assoc = (ecx >> 12) & 0xf;
73 if (assoc == 6)
74 assoc = 8;
75 else if (assoc == 8)
76 assoc = 16;
77 else if (assoc >= 0xa && assoc <= 0xc)
78 assoc = 32 + (assoc - 0xa) * 16;
79 else if (assoc >= 0xd && assoc <= 0xe)
80 assoc = 96 + (assoc - 0xd) * 32;
81
82 level2->assoc = assoc;
83 }
84
85 /* Returns the description of caches for an AMD processor. */
86
87 static const char *
88 detect_caches_amd (unsigned max_ext_level)
89 {
90 unsigned eax, ebx, ecx, edx;
91
92 struct cache_desc level1, level2 = {0, 0, 0};
93
94 if (max_ext_level < 0x80000005)
95 return "";
96
97 __cpuid (0x80000005, eax, ebx, ecx, edx);
98
99 level1.sizekb = (ecx >> 24) & 0xff;
100 level1.assoc = (ecx >> 16) & 0xff;
101 level1.line = ecx & 0xff;
102
103 if (max_ext_level >= 0x80000006)
104 detect_l2_cache (&level2);
105
106 return describe_cache (level1, level2);
107 }
108
109 /* Decodes the size, the associativity and the cache line size of
110 L1/L2 caches of an Intel processor. Values are based on
111 "Intel Processor Identification and the CPUID Instruction"
112 [Application Note 485], revision -032, December 2007. */
113
114 static void
115 decode_caches_intel (unsigned reg, bool xeon_mp,
116 struct cache_desc *level1, struct cache_desc *level2)
117 {
118 int i;
119
120 for (i = 24; i >= 0; i -= 8)
121 switch ((reg >> i) & 0xff)
122 {
123 case 0x0a:
124 level1->sizekb = 8; level1->assoc = 2; level1->line = 32;
125 break;
126 case 0x0c:
127 level1->sizekb = 16; level1->assoc = 4; level1->line = 32;
128 break;
129 case 0x2c:
130 level1->sizekb = 32; level1->assoc = 8; level1->line = 64;
131 break;
132 case 0x39:
133 level2->sizekb = 128; level2->assoc = 4; level2->line = 64;
134 break;
135 case 0x3a:
136 level2->sizekb = 192; level2->assoc = 6; level2->line = 64;
137 break;
138 case 0x3b:
139 level2->sizekb = 128; level2->assoc = 2; level2->line = 64;
140 break;
141 case 0x3c:
142 level2->sizekb = 256; level2->assoc = 4; level2->line = 64;
143 break;
144 case 0x3d:
145 level2->sizekb = 384; level2->assoc = 6; level2->line = 64;
146 break;
147 case 0x3e:
148 level2->sizekb = 512; level2->assoc = 4; level2->line = 64;
149 break;
150 case 0x41:
151 level2->sizekb = 128; level2->assoc = 4; level2->line = 32;
152 break;
153 case 0x42:
154 level2->sizekb = 256; level2->assoc = 4; level2->line = 32;
155 break;
156 case 0x43:
157 level2->sizekb = 512; level2->assoc = 4; level2->line = 32;
158 break;
159 case 0x44:
160 level2->sizekb = 1024; level2->assoc = 4; level2->line = 32;
161 break;
162 case 0x45:
163 level2->sizekb = 2048; level2->assoc = 4; level2->line = 32;
164 break;
165 case 0x49:
166 if (xeon_mp)
167 break;
168 level2->sizekb = 4096; level2->assoc = 16; level2->line = 64;
169 break;
170 case 0x4e:
171 level2->sizekb = 6144; level2->assoc = 24; level2->line = 64;
172 break;
173 case 0x60:
174 level1->sizekb = 16; level1->assoc = 8; level1->line = 64;
175 break;
176 case 0x66:
177 level1->sizekb = 8; level1->assoc = 4; level1->line = 64;
178 break;
179 case 0x67:
180 level1->sizekb = 16; level1->assoc = 4; level1->line = 64;
181 break;
182 case 0x68:
183 level1->sizekb = 32; level1->assoc = 4; level1->line = 64;
184 break;
185 case 0x78:
186 level2->sizekb = 1024; level2->assoc = 4; level2->line = 64;
187 break;
188 case 0x79:
189 level2->sizekb = 128; level2->assoc = 8; level2->line = 64;
190 break;
191 case 0x7a:
192 level2->sizekb = 256; level2->assoc = 8; level2->line = 64;
193 break;
194 case 0x7b:
195 level2->sizekb = 512; level2->assoc = 8; level2->line = 64;
196 break;
197 case 0x7c:
198 level2->sizekb = 1024; level2->assoc = 8; level2->line = 64;
199 break;
200 case 0x7d:
201 level2->sizekb = 2048; level2->assoc = 8; level2->line = 64;
202 break;
203 case 0x7f:
204 level2->sizekb = 512; level2->assoc = 2; level2->line = 64;
205 break;
206 case 0x82:
207 level2->sizekb = 256; level2->assoc = 8; level2->line = 32;
208 break;
209 case 0x83:
210 level2->sizekb = 512; level2->assoc = 8; level2->line = 32;
211 break;
212 case 0x84:
213 level2->sizekb = 1024; level2->assoc = 8; level2->line = 32;
214 break;
215 case 0x85:
216 level2->sizekb = 2048; level2->assoc = 8; level2->line = 32;
217 break;
218 case 0x86:
219 level2->sizekb = 512; level2->assoc = 4; level2->line = 64;
220 break;
221 case 0x87:
222 level2->sizekb = 1024; level2->assoc = 8; level2->line = 64;
223
224 default:
225 break;
226 }
227 }
228
229 /* Detect cache parameters using CPUID function 2. */
230
231 static void
232 detect_caches_cpuid2 (bool xeon_mp,
233 struct cache_desc *level1, struct cache_desc *level2)
234 {
235 unsigned regs[4];
236 int nreps, i;
237
238 __cpuid (2, regs[0], regs[1], regs[2], regs[3]);
239
240 nreps = regs[0] & 0x0f;
241 regs[0] &= ~0x0f;
242
243 while (--nreps >= 0)
244 {
245 for (i = 0; i < 4; i++)
246 if (regs[i] && !((regs[i] >> 31) & 1))
247 decode_caches_intel (regs[i], xeon_mp, level1, level2);
248
249 if (nreps)
250 __cpuid (2, regs[0], regs[1], regs[2], regs[3]);
251 }
252 }
253
254 /* Detect cache parameters using CPUID function 4. This
255 method doesn't require hardcoded tables. */
256
257 enum cache_type
258 {
259 CACHE_END = 0,
260 CACHE_DATA = 1,
261 CACHE_INST = 2,
262 CACHE_UNIFIED = 3
263 };
264
265 static void
266 detect_caches_cpuid4 (struct cache_desc *level1, struct cache_desc *level2,
267 struct cache_desc *level3)
268 {
269 struct cache_desc *cache;
270
271 unsigned eax, ebx, ecx, edx;
272 int count;
273
274 for (count = 0;; count++)
275 {
276 __cpuid_count(4, count, eax, ebx, ecx, edx);
277 switch (eax & 0x1f)
278 {
279 case CACHE_END:
280 return;
281 case CACHE_DATA:
282 case CACHE_UNIFIED:
283 {
284 switch ((eax >> 5) & 0x07)
285 {
286 case 1:
287 cache = level1;
288 break;
289 case 2:
290 cache = level2;
291 break;
292 case 3:
293 cache = level3;
294 break;
295 default:
296 cache = NULL;
297 }
298
299 if (cache)
300 {
301 unsigned sets = ecx + 1;
302 unsigned part = ((ebx >> 12) & 0x03ff) + 1;
303
304 cache->assoc = ((ebx >> 22) & 0x03ff) + 1;
305 cache->line = (ebx & 0x0fff) + 1;
306
307 cache->sizekb = (cache->assoc * part
308 * cache->line * sets) / 1024;
309 }
310 }
311 default:
312 break;
313 }
314 }
315 }
316
317 /* Returns the description of caches for an Intel processor. */
318
319 static const char *
320 detect_caches_intel (bool xeon_mp, unsigned max_level,
321 unsigned max_ext_level, unsigned *l2sizekb)
322 {
323 struct cache_desc level1 = {0, 0, 0}, level2 = {0, 0, 0}, level3 = {0, 0, 0};
324
325 if (max_level >= 4)
326 detect_caches_cpuid4 (&level1, &level2, &level3);
327 else if (max_level >= 2)
328 detect_caches_cpuid2 (xeon_mp, &level1, &level2);
329 else
330 return "";
331
332 if (level1.sizekb == 0)
333 return "";
334
335 /* Let the L3 replace the L2. This assumes inclusive caches
336 and single threaded program for now. */
337 if (level3.sizekb)
338 level2 = level3;
339
340 /* Intel CPUs are equipped with AMD style L2 cache info. Try this
341 method if other methods fail to provide L2 cache parameters. */
342 if (level2.sizekb == 0 && max_ext_level >= 0x80000006)
343 detect_l2_cache (&level2);
344
345 *l2sizekb = level2.sizekb;
346
347 return describe_cache (level1, level2);
348 }
349
350 enum vendor_signatures
351 {
352 SIG_INTEL = 0x756e6547 /* Genu */,
353 SIG_AMD = 0x68747541 /* Auth */
354 };
355
356 enum processor_signatures
357 {
358 SIG_GEODE = 0x646f6547 /* Geod */
359 };
360
361 /* This will be called by the spec parser in gcc.c when it sees
362 a %:local_cpu_detect(args) construct. Currently it will be called
363 with either "arch" or "tune" as argument depending on if -march=native
364 or -mtune=native is to be substituted.
365
366 It returns a string containing new command line parameters to be
367 put at the place of the above two options, depending on what CPU
368 this is executed. E.g. "-march=k8" on an AMD64 machine
369 for -march=native.
370
371 ARGC and ARGV are set depending on the actual arguments given
372 in the spec. */
373
374 const char *host_detect_local_cpu (int argc, const char **argv)
375 {
376 enum processor_type processor = PROCESSOR_I386;
377 const char *cpu = "i386";
378
379 const char *cache = "";
380 const char *options = "";
381
382 unsigned int eax, ebx, ecx, edx;
383
384 unsigned int max_level, ext_level;
385
386 unsigned int vendor;
387 unsigned int model, family;
388
389 unsigned int has_sse3, has_ssse3, has_cmpxchg16b;
390 unsigned int has_cmpxchg8b, has_cmov, has_mmx, has_sse, has_sse2;
391
392 /* Extended features */
393 unsigned int has_lahf_lm = 0, has_sse4a = 0;
394 unsigned int has_longmode = 0, has_3dnowp = 0, has_3dnow = 0;
395 unsigned int has_movbe = 0, has_sse4_1 = 0, has_sse4_2 = 0;
396 unsigned int has_popcnt = 0, has_aes = 0, has_avx = 0, has_avx2 = 0;
397 unsigned int has_pclmul = 0, has_abm = 0, has_lwp = 0;
398 unsigned int has_fma = 0, has_fma4 = 0, has_xop = 0;
399 unsigned int has_bmi = 0, has_bmi2 = 0, has_tbm = 0, has_lzcnt = 0;
400 unsigned int has_hle = 0;
401
402 bool arch;
403
404 unsigned int l2sizekb = 0;
405
406 if (argc < 1)
407 return NULL;
408
409 arch = !strcmp (argv[0], "arch");
410
411 if (!arch && strcmp (argv[0], "tune"))
412 return NULL;
413
414 max_level = __get_cpuid_max (0, &vendor);
415 if (max_level < 1)
416 goto done;
417
418 __cpuid (1, eax, ebx, ecx, edx);
419
420 model = (eax >> 4) & 0x0f;
421 family = (eax >> 8) & 0x0f;
422 if (vendor == SIG_INTEL)
423 {
424 unsigned int extended_model, extended_family;
425
426 extended_model = (eax >> 12) & 0xf0;
427 extended_family = (eax >> 20) & 0xff;
428 if (family == 0x0f)
429 {
430 family += extended_family;
431 model += extended_model;
432 }
433 else if (family == 0x06)
434 model += extended_model;
435 }
436
437 has_sse3 = ecx & bit_SSE3;
438 has_ssse3 = ecx & bit_SSSE3;
439 has_sse4_1 = ecx & bit_SSE4_1;
440 has_sse4_2 = ecx & bit_SSE4_2;
441 has_avx = ecx & bit_AVX;
442 has_cmpxchg16b = ecx & bit_CMPXCHG16B;
443 has_movbe = ecx & bit_MOVBE;
444 has_popcnt = ecx & bit_POPCNT;
445 has_aes = ecx & bit_AES;
446 has_pclmul = ecx & bit_PCLMUL;
447 has_fma = ecx & bit_FMA;
448
449 has_cmpxchg8b = edx & bit_CMPXCHG8B;
450 has_cmov = edx & bit_CMOV;
451 has_mmx = edx & bit_MMX;
452 has_sse = edx & bit_SSE;
453 has_sse2 = edx & bit_SSE2;
454
455 if (max_level >= 7)
456 {
457 __cpuid_count (7, 0, eax, ebx, ecx, edx);
458
459 has_bmi = ebx & bit_BMI;
460 has_hle = ebx & bit_HLE;
461 has_avx2 = ebx & bit_AVX2;
462 has_bmi2 = ebx & bit_BMI2;
463 }
464
465 /* Check cpuid level of extended features. */
466 __cpuid (0x80000000, ext_level, ebx, ecx, edx);
467
468 if (ext_level > 0x80000000)
469 {
470 __cpuid (0x80000001, eax, ebx, ecx, edx);
471
472 has_lahf_lm = ecx & bit_LAHF_LM;
473 has_sse4a = ecx & bit_SSE4a;
474 has_abm = ecx & bit_ABM;
475 has_lwp = ecx & bit_LWP;
476 has_fma4 = ecx & bit_FMA4;
477 if (vendor == SIG_AMD && has_fma4 && has_fma)
478 has_fma4 = 0;
479 has_xop = ecx & bit_XOP;
480 has_tbm = ecx & bit_TBM;
481 has_lzcnt = ecx & bit_LZCNT;
482
483 has_longmode = edx & bit_LM;
484 has_3dnowp = edx & bit_3DNOWP;
485 has_3dnow = edx & bit_3DNOW;
486 }
487
488 if (!arch)
489 {
490 if (vendor == SIG_AMD)
491 cache = detect_caches_amd (ext_level);
492 else if (vendor == SIG_INTEL)
493 {
494 bool xeon_mp = (family == 15 && model == 6);
495 cache = detect_caches_intel (xeon_mp, max_level,
496 ext_level, &l2sizekb);
497 }
498 }
499
500 if (vendor == SIG_AMD)
501 {
502 unsigned int name;
503
504 /* Detect geode processor by its processor signature. */
505 if (ext_level > 0x80000001)
506 __cpuid (0x80000002, name, ebx, ecx, edx);
507 else
508 name = 0;
509
510 if (name == SIG_GEODE)
511 processor = PROCESSOR_GEODE;
512 else if (has_bmi)
513 processor = PROCESSOR_BDVER2;
514 else if (has_xop)
515 processor = PROCESSOR_BDVER1;
516 else if (has_sse4a && has_ssse3)
517 processor = PROCESSOR_BTVER1;
518 else if (has_sse4a)
519 processor = PROCESSOR_AMDFAM10;
520 else if (has_sse2 || has_longmode)
521 processor = PROCESSOR_K8;
522 else if (has_3dnowp && family == 6)
523 processor = PROCESSOR_ATHLON;
524 else if (has_mmx)
525 processor = PROCESSOR_K6;
526 else
527 processor = PROCESSOR_PENTIUM;
528 }
529 else
530 {
531 switch (family)
532 {
533 case 4:
534 processor = PROCESSOR_I486;
535 break;
536 case 5:
537 processor = PROCESSOR_PENTIUM;
538 break;
539 case 6:
540 processor = PROCESSOR_PENTIUMPRO;
541 break;
542 case 15:
543 processor = PROCESSOR_PENTIUM4;
544 break;
545 default:
546 /* We have no idea. */
547 processor = PROCESSOR_GENERIC32;
548 }
549 }
550
551 switch (processor)
552 {
553 case PROCESSOR_I386:
554 /* Default. */
555 break;
556 case PROCESSOR_I486:
557 cpu = "i486";
558 break;
559 case PROCESSOR_PENTIUM:
560 if (arch && has_mmx)
561 cpu = "pentium-mmx";
562 else
563 cpu = "pentium";
564 break;
565 case PROCESSOR_PENTIUMPRO:
566 switch (model)
567 {
568 case 0x1c:
569 case 0x26:
570 /* Atom. */
571 cpu = "atom";
572 break;
573 case 0x1a:
574 case 0x1e:
575 case 0x1f:
576 case 0x2e:
577 /* Nehalem. */
578 cpu = "corei7";
579 break;
580 case 0x25:
581 case 0x2c:
582 case 0x2f:
583 /* Westmere. */
584 cpu = "corei7";
585 break;
586 case 0x2a:
587 case 0x2d:
588 /* Sandy Bridge. */
589 cpu = "corei7-avx";
590 break;
591 case 0x17:
592 case 0x1d:
593 /* Penryn. */
594 cpu = "core2";
595 break;
596 case 0x0f:
597 /* Merom. */
598 cpu = "core2";
599 break;
600 default:
601 if (arch)
602 {
603 /* This is unknown family 0x6 CPU. */
604 if (has_avx)
605 /* Assume Sandy Bridge. */
606 cpu = "corei7-avx";
607 else if (has_sse4_2)
608 /* Assume Core i7. */
609 cpu = "corei7";
610 else if (has_ssse3)
611 {
612 if (has_movbe)
613 /* Assume Atom. */
614 cpu = "atom";
615 else
616 /* Assume Core 2. */
617 cpu = "core2";
618 }
619 else if (has_sse3)
620 /* It is Core Duo. */
621 cpu = "pentium-m";
622 else if (has_sse2)
623 /* It is Pentium M. */
624 cpu = "pentium-m";
625 else if (has_sse)
626 /* It is Pentium III. */
627 cpu = "pentium3";
628 else if (has_mmx)
629 /* It is Pentium II. */
630 cpu = "pentium2";
631 else
632 /* Default to Pentium Pro. */
633 cpu = "pentiumpro";
634 }
635 else
636 /* For -mtune, we default to -mtune=generic. */
637 cpu = "generic";
638 break;
639 }
640 break;
641 case PROCESSOR_PENTIUM4:
642 if (has_sse3)
643 {
644 if (has_longmode)
645 cpu = "nocona";
646 else
647 cpu = "prescott";
648 }
649 else
650 cpu = "pentium4";
651 break;
652 case PROCESSOR_GEODE:
653 cpu = "geode";
654 break;
655 case PROCESSOR_K6:
656 if (arch && has_3dnow)
657 cpu = "k6-3";
658 else
659 cpu = "k6";
660 break;
661 case PROCESSOR_ATHLON:
662 if (arch && has_sse)
663 cpu = "athlon-4";
664 else
665 cpu = "athlon";
666 break;
667 case PROCESSOR_K8:
668 if (arch && has_sse3)
669 cpu = "k8-sse3";
670 else
671 cpu = "k8";
672 break;
673 case PROCESSOR_AMDFAM10:
674 cpu = "amdfam10";
675 break;
676 case PROCESSOR_BDVER1:
677 cpu = "bdver1";
678 break;
679 case PROCESSOR_BDVER2:
680 cpu = "bdver2";
681 break;
682 case PROCESSOR_BTVER1:
683 cpu = "btver1";
684 break;
685
686 default:
687 /* Use something reasonable. */
688 if (arch)
689 {
690 if (has_ssse3)
691 cpu = "core2";
692 else if (has_sse3)
693 {
694 if (has_longmode)
695 cpu = "nocona";
696 else
697 cpu = "prescott";
698 }
699 else if (has_sse2)
700 cpu = "pentium4";
701 else if (has_cmov)
702 cpu = "pentiumpro";
703 else if (has_mmx)
704 cpu = "pentium-mmx";
705 else if (has_cmpxchg8b)
706 cpu = "pentium";
707 }
708 else
709 cpu = "generic";
710 }
711
712 if (arch)
713 {
714 const char *cx16 = has_cmpxchg16b ? " -mcx16" : " -mno-cx16";
715 const char *sahf = has_lahf_lm ? " -msahf" : " -mno-sahf";
716 const char *movbe = has_movbe ? " -mmovbe" : " -mno-movbe";
717 const char *ase = has_aes ? " -maes" : " -mno-aes";
718 const char *pclmul = has_pclmul ? " -mpclmul" : " -mno-pclmul";
719 const char *popcnt = has_popcnt ? " -mpopcnt" : " -mno-popcnt";
720 const char *abm = has_abm ? " -mabm" : " -mno-abm";
721 const char *lwp = has_lwp ? " -mlwp" : " -mno-lwp";
722 const char *fma = has_fma ? " -mfma" : " -mno-fma";
723 const char *fma4 = has_fma4 ? " -mfma4" : " -mno-fma4";
724 const char *xop = has_xop ? " -mxop" : " -mno-xop";
725 const char *bmi = has_bmi ? " -mbmi" : " -mno-bmi";
726 const char *bmi2 = has_bmi2 ? " -mbmi2" : " -mno-bmi2";
727 const char *tbm = has_tbm ? " -mtbm" : " -mno-tbm";
728 const char *avx = has_avx ? " -mavx" : " -mno-avx";
729 const char *avx2 = has_avx2 ? " -mavx2" : " -mno-avx2";
730 const char *sse4_2 = has_sse4_2 ? " -msse4.2" : " -mno-sse4.2";
731 const char *sse4_1 = has_sse4_1 ? " -msse4.1" : " -mno-sse4.1";
732 const char *lzcnt = has_lzcnt ? " -mlzcnt" : " -mno-lzcnt";
733 const char *hle = has_hle ? " -mhle" : " -mno-hle";
734
735 options = concat (options, cx16, sahf, movbe, ase, pclmul,
736 popcnt, abm, lwp, fma, fma4, xop, bmi, bmi2,
737 tbm, avx, avx2, sse4_2, sse4_1, lzcnt,
738 hle, NULL);
739 }
740
741 done:
742 return concat (cache, "-m", argv[0], "=", cpu, options, NULL);
743 }
744 #else
745
746 /* If we aren't compiling with GCC then the driver will just ignore
747 -march and -mtune "native" target and will leave to the newly
748 built compiler to generate code for its default target. */
749
750 const char *host_detect_local_cpu (int argc ATTRIBUTE_UNUSED,
751 const char **argv ATTRIBUTE_UNUSED)
752 {
753 return NULL;
754 }
755 #endif /* __GNUC__ */