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  1. /*
  2. * Assembly testing and benchmarking tool
  3. * Copyright (c) 2015 Henrik Gramner
  4. * Copyright (c) 2008 Loren Merritt
  5. *
  6. * This file is part of FFmpeg.
  7. *
  8. * FFmpeg is free software; you can redistribute it and/or modify
  9. * it under the terms of the GNU General Public License as published by
  10. * the Free Software Foundation; either version 2 of the License, or
  11. * (at your option) any later version.
  12. *
  13. * FFmpeg is distributed in the hope that it will be useful,
  14. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16. * GNU General Public License for more details.
  17. *
  18. * You should have received a copy of the GNU General Public License along
  19. * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
  20. * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21. */
  22. #include <stdarg.h>
  23. #include <stdio.h>
  24. #include <stdlib.h>
  25. #include <string.h>
  26. #include "checkasm.h"
  27. #include "libavutil/common.h"
  28. #include "libavutil/cpu.h"
  29. #include "libavutil/intfloat.h"
  30. #include "libavutil/random_seed.h"
  31. #if HAVE_IO_H
  32. #include <io.h>
  33. #endif
  34. #if HAVE_SETCONSOLETEXTATTRIBUTE
  35. #include <windows.h>
  36. #define COLOR_RED FOREGROUND_RED
  37. #define COLOR_GREEN FOREGROUND_GREEN
  38. #define COLOR_YELLOW (FOREGROUND_RED|FOREGROUND_GREEN)
  39. #else
  40. #define COLOR_RED 1
  41. #define COLOR_GREEN 2
  42. #define COLOR_YELLOW 3
  43. #endif
  44. #if HAVE_UNISTD_H
  45. #include <unistd.h>
  46. #endif
  47. #if !HAVE_ISATTY
  48. #define isatty(fd) 1
  49. #endif
  50. #if ARCH_ARM && HAVE_ARMV5TE_EXTERNAL
  51. #include "libavutil/arm/cpu.h"
  52. void (*checkasm_checked_call)(void *func, int dummy, ...) = checkasm_checked_call_novfp;
  53. #endif
  54. /* List of tests to invoke */
  55. static const struct {
  56. const char *name;
  57. void (*func)(void);
  58. } tests[] = {
  59. #if CONFIG_AVCODEC
  60. #if CONFIG_ALAC_DECODER
  61. { "alacdsp", checkasm_check_alacdsp },
  62. #endif
  63. #if CONFIG_AUDIODSP
  64. { "audiodsp", checkasm_check_audiodsp },
  65. #endif
  66. #if CONFIG_BLOCKDSP
  67. { "blockdsp", checkasm_check_blockdsp },
  68. #endif
  69. #if CONFIG_BSWAPDSP
  70. { "bswapdsp", checkasm_check_bswapdsp },
  71. #endif
  72. #if CONFIG_DCA_DECODER
  73. { "synth_filter", checkasm_check_synth_filter },
  74. #endif
  75. #if CONFIG_FLACDSP
  76. { "flacdsp", checkasm_check_flacdsp },
  77. #endif
  78. #if CONFIG_FMTCONVERT
  79. { "fmtconvert", checkasm_check_fmtconvert },
  80. #endif
  81. #if CONFIG_H264DSP
  82. { "h264dsp", checkasm_check_h264dsp },
  83. #endif
  84. #if CONFIG_H264PRED
  85. { "h264pred", checkasm_check_h264pred },
  86. #endif
  87. #if CONFIG_H264QPEL
  88. { "h264qpel", checkasm_check_h264qpel },
  89. #endif
  90. #if CONFIG_HEVC_DECODER
  91. { "hevc_idct", checkasm_check_hevc_idct },
  92. #endif
  93. #if CONFIG_JPEG2000_DECODER
  94. { "jpeg2000dsp", checkasm_check_jpeg2000dsp },
  95. #endif
  96. #if CONFIG_HUFFYUVDSP
  97. { "llviddsp", checkasm_check_llviddsp },
  98. #endif
  99. #if CONFIG_PIXBLOCKDSP
  100. { "pixblockdsp", checkasm_check_pixblockdsp },
  101. #endif
  102. #if CONFIG_V210_ENCODER
  103. { "v210enc", checkasm_check_v210enc },
  104. #endif
  105. #if CONFIG_VP8DSP
  106. { "vp8dsp", checkasm_check_vp8dsp },
  107. #endif
  108. #if CONFIG_VP9_DECODER
  109. { "vp9dsp", checkasm_check_vp9dsp },
  110. #endif
  111. #if CONFIG_VIDEODSP
  112. { "videodsp", checkasm_check_videodsp },
  113. #endif
  114. #endif
  115. #if CONFIG_AVFILTER
  116. #if CONFIG_BLEND_FILTER
  117. { "vf_blend", checkasm_check_blend },
  118. #endif
  119. #if CONFIG_COLORSPACE_FILTER
  120. { "vf_colorspace", checkasm_check_colorspace },
  121. #endif
  122. #endif
  123. { NULL }
  124. };
  125. /* List of cpu flags to check */
  126. static const struct {
  127. const char *name;
  128. const char *suffix;
  129. int flag;
  130. } cpus[] = {
  131. #if ARCH_AARCH64
  132. { "ARMV8", "armv8", AV_CPU_FLAG_ARMV8 },
  133. { "NEON", "neon", AV_CPU_FLAG_NEON },
  134. #elif ARCH_ARM
  135. { "ARMV5TE", "armv5te", AV_CPU_FLAG_ARMV5TE },
  136. { "ARMV6", "armv6", AV_CPU_FLAG_ARMV6 },
  137. { "ARMV6T2", "armv6t2", AV_CPU_FLAG_ARMV6T2 },
  138. { "VFP", "vfp", AV_CPU_FLAG_VFP },
  139. { "VFP_VM", "vfp_vm", AV_CPU_FLAG_VFP_VM },
  140. { "VFPV3", "vfp3", AV_CPU_FLAG_VFPV3 },
  141. { "NEON", "neon", AV_CPU_FLAG_NEON },
  142. #elif ARCH_PPC
  143. { "ALTIVEC", "altivec", AV_CPU_FLAG_ALTIVEC },
  144. { "VSX", "vsx", AV_CPU_FLAG_VSX },
  145. { "POWER8", "power8", AV_CPU_FLAG_POWER8 },
  146. #elif ARCH_X86
  147. { "MMX", "mmx", AV_CPU_FLAG_MMX|AV_CPU_FLAG_CMOV },
  148. { "MMXEXT", "mmxext", AV_CPU_FLAG_MMXEXT },
  149. { "3DNOW", "3dnow", AV_CPU_FLAG_3DNOW },
  150. { "3DNOWEXT", "3dnowext", AV_CPU_FLAG_3DNOWEXT },
  151. { "SSE", "sse", AV_CPU_FLAG_SSE },
  152. { "SSE2", "sse2", AV_CPU_FLAG_SSE2|AV_CPU_FLAG_SSE2SLOW },
  153. { "SSE3", "sse3", AV_CPU_FLAG_SSE3|AV_CPU_FLAG_SSE3SLOW },
  154. { "SSSE3", "ssse3", AV_CPU_FLAG_SSSE3|AV_CPU_FLAG_ATOM },
  155. { "SSE4.1", "sse4", AV_CPU_FLAG_SSE4 },
  156. { "SSE4.2", "sse42", AV_CPU_FLAG_SSE42 },
  157. { "AES-NI", "aesni", AV_CPU_FLAG_AESNI },
  158. { "AVX", "avx", AV_CPU_FLAG_AVX },
  159. { "XOP", "xop", AV_CPU_FLAG_XOP },
  160. { "FMA3", "fma3", AV_CPU_FLAG_FMA3 },
  161. { "FMA4", "fma4", AV_CPU_FLAG_FMA4 },
  162. { "AVX2", "avx2", AV_CPU_FLAG_AVX2 },
  163. #endif
  164. { NULL }
  165. };
  166. typedef struct CheckasmFuncVersion {
  167. struct CheckasmFuncVersion *next;
  168. void *func;
  169. int ok;
  170. int cpu;
  171. int iterations;
  172. uint64_t cycles;
  173. } CheckasmFuncVersion;
  174. /* Binary search tree node */
  175. typedef struct CheckasmFunc {
  176. struct CheckasmFunc *child[2];
  177. CheckasmFuncVersion versions;
  178. uint8_t color; /* 0 = red, 1 = black */
  179. char name[1];
  180. } CheckasmFunc;
  181. /* Internal state */
  182. static struct {
  183. CheckasmFunc *funcs;
  184. CheckasmFunc *current_func;
  185. CheckasmFuncVersion *current_func_ver;
  186. const char *current_test_name;
  187. const char *bench_pattern;
  188. int bench_pattern_len;
  189. int num_checked;
  190. int num_failed;
  191. int nop_time;
  192. int cpu_flag;
  193. const char *cpu_flag_name;
  194. } state;
  195. /* PRNG state */
  196. AVLFG checkasm_lfg;
  197. /* float compare support code */
  198. static int is_negative(union av_intfloat32 u)
  199. {
  200. return u.i >> 31;
  201. }
  202. int float_near_ulp(float a, float b, unsigned max_ulp)
  203. {
  204. union av_intfloat32 x, y;
  205. x.f = a;
  206. y.f = b;
  207. if (is_negative(x) != is_negative(y)) {
  208. // handle -0.0 == +0.0
  209. return a == b;
  210. }
  211. if (llabs((int64_t)x.i - y.i) <= max_ulp)
  212. return 1;
  213. return 0;
  214. }
  215. int float_near_ulp_array(const float *a, const float *b, unsigned max_ulp,
  216. unsigned len)
  217. {
  218. unsigned i;
  219. for (i = 0; i < len; i++) {
  220. if (!float_near_ulp(a[i], b[i], max_ulp))
  221. return 0;
  222. }
  223. return 1;
  224. }
  225. int float_near_abs_eps(float a, float b, float eps)
  226. {
  227. float abs_diff = fabsf(a - b);
  228. return abs_diff < eps;
  229. }
  230. int float_near_abs_eps_array(const float *a, const float *b, float eps,
  231. unsigned len)
  232. {
  233. unsigned i;
  234. for (i = 0; i < len; i++) {
  235. if (!float_near_abs_eps(a[i], b[i], eps))
  236. return 0;
  237. }
  238. return 1;
  239. }
  240. int float_near_abs_eps_ulp(float a, float b, float eps, unsigned max_ulp)
  241. {
  242. return float_near_ulp(a, b, max_ulp) || float_near_abs_eps(a, b, eps);
  243. }
  244. int float_near_abs_eps_array_ulp(const float *a, const float *b, float eps,
  245. unsigned max_ulp, unsigned len)
  246. {
  247. unsigned i;
  248. for (i = 0; i < len; i++) {
  249. if (!float_near_abs_eps_ulp(a[i], b[i], eps, max_ulp))
  250. return 0;
  251. }
  252. return 1;
  253. }
  254. /* Print colored text to stderr if the terminal supports it */
  255. static void color_printf(int color, const char *fmt, ...)
  256. {
  257. static int use_color = -1;
  258. va_list arg;
  259. #if HAVE_SETCONSOLETEXTATTRIBUTE
  260. static HANDLE con;
  261. static WORD org_attributes;
  262. if (use_color < 0) {
  263. CONSOLE_SCREEN_BUFFER_INFO con_info;
  264. con = GetStdHandle(STD_ERROR_HANDLE);
  265. if (con && con != INVALID_HANDLE_VALUE && GetConsoleScreenBufferInfo(con, &con_info)) {
  266. org_attributes = con_info.wAttributes;
  267. use_color = 1;
  268. } else
  269. use_color = 0;
  270. }
  271. if (use_color)
  272. SetConsoleTextAttribute(con, (org_attributes & 0xfff0) | (color & 0x0f));
  273. #else
  274. if (use_color < 0) {
  275. const char *term = getenv("TERM");
  276. use_color = term && strcmp(term, "dumb") && isatty(2);
  277. }
  278. if (use_color)
  279. fprintf(stderr, "\x1b[%d;3%dm", (color & 0x08) >> 3, color & 0x07);
  280. #endif
  281. va_start(arg, fmt);
  282. vfprintf(stderr, fmt, arg);
  283. va_end(arg);
  284. if (use_color) {
  285. #if HAVE_SETCONSOLETEXTATTRIBUTE
  286. SetConsoleTextAttribute(con, org_attributes);
  287. #else
  288. fprintf(stderr, "\x1b[0m");
  289. #endif
  290. }
  291. }
  292. /* Deallocate a tree */
  293. static void destroy_func_tree(CheckasmFunc *f)
  294. {
  295. if (f) {
  296. CheckasmFuncVersion *v = f->versions.next;
  297. while (v) {
  298. CheckasmFuncVersion *next = v->next;
  299. free(v);
  300. v = next;
  301. }
  302. destroy_func_tree(f->child[0]);
  303. destroy_func_tree(f->child[1]);
  304. free(f);
  305. }
  306. }
  307. /* Allocate a zero-initialized block, clean up and exit on failure */
  308. static void *checkasm_malloc(size_t size)
  309. {
  310. void *ptr = calloc(1, size);
  311. if (!ptr) {
  312. fprintf(stderr, "checkasm: malloc failed\n");
  313. destroy_func_tree(state.funcs);
  314. exit(1);
  315. }
  316. return ptr;
  317. }
  318. /* Get the suffix of the specified cpu flag */
  319. static const char *cpu_suffix(int cpu)
  320. {
  321. int i = FF_ARRAY_ELEMS(cpus);
  322. while (--i >= 0)
  323. if (cpu & cpus[i].flag)
  324. return cpus[i].suffix;
  325. return "c";
  326. }
  327. #ifdef AV_READ_TIME
  328. static int cmp_nop(const void *a, const void *b)
  329. {
  330. return *(const uint16_t*)a - *(const uint16_t*)b;
  331. }
  332. /* Measure the overhead of the timing code (in decicycles) */
  333. static int measure_nop_time(void)
  334. {
  335. uint16_t nops[10000];
  336. int i, nop_sum = 0;
  337. for (i = 0; i < 10000; i++) {
  338. uint64_t t = AV_READ_TIME();
  339. nops[i] = AV_READ_TIME() - t;
  340. }
  341. qsort(nops, 10000, sizeof(uint16_t), cmp_nop);
  342. for (i = 2500; i < 7500; i++)
  343. nop_sum += nops[i];
  344. return nop_sum / 500;
  345. }
  346. /* Print benchmark results */
  347. static void print_benchs(CheckasmFunc *f)
  348. {
  349. if (f) {
  350. print_benchs(f->child[0]);
  351. /* Only print functions with at least one assembly version */
  352. if (f->versions.cpu || f->versions.next) {
  353. CheckasmFuncVersion *v = &f->versions;
  354. do {
  355. if (v->iterations) {
  356. int decicycles = (10*v->cycles/v->iterations - state.nop_time) / 4;
  357. printf("%s_%s: %d.%d\n", f->name, cpu_suffix(v->cpu), decicycles/10, decicycles%10);
  358. }
  359. } while ((v = v->next));
  360. }
  361. print_benchs(f->child[1]);
  362. }
  363. }
  364. #endif
  365. /* ASCIIbetical sort except preserving natural order for numbers */
  366. static int cmp_func_names(const char *a, const char *b)
  367. {
  368. const char *start = a;
  369. int ascii_diff, digit_diff;
  370. for (; !(ascii_diff = *(const unsigned char*)a - *(const unsigned char*)b) && *a; a++, b++);
  371. for (; av_isdigit(*a) && av_isdigit(*b); a++, b++);
  372. if (a > start && av_isdigit(a[-1]) && (digit_diff = av_isdigit(*a) - av_isdigit(*b)))
  373. return digit_diff;
  374. return ascii_diff;
  375. }
  376. /* Perform a tree rotation in the specified direction and return the new root */
  377. static CheckasmFunc *rotate_tree(CheckasmFunc *f, int dir)
  378. {
  379. CheckasmFunc *r = f->child[dir^1];
  380. f->child[dir^1] = r->child[dir];
  381. r->child[dir] = f;
  382. r->color = f->color;
  383. f->color = 0;
  384. return r;
  385. }
  386. #define is_red(f) ((f) && !(f)->color)
  387. /* Balance a left-leaning red-black tree at the specified node */
  388. static void balance_tree(CheckasmFunc **root)
  389. {
  390. CheckasmFunc *f = *root;
  391. if (is_red(f->child[0]) && is_red(f->child[1])) {
  392. f->color ^= 1;
  393. f->child[0]->color = f->child[1]->color = 1;
  394. }
  395. if (!is_red(f->child[0]) && is_red(f->child[1]))
  396. *root = rotate_tree(f, 0); /* Rotate left */
  397. else if (is_red(f->child[0]) && is_red(f->child[0]->child[0]))
  398. *root = rotate_tree(f, 1); /* Rotate right */
  399. }
  400. /* Get a node with the specified name, creating it if it doesn't exist */
  401. static CheckasmFunc *get_func(CheckasmFunc **root, const char *name)
  402. {
  403. CheckasmFunc *f = *root;
  404. if (f) {
  405. /* Search the tree for a matching node */
  406. int cmp = cmp_func_names(name, f->name);
  407. if (cmp) {
  408. f = get_func(&f->child[cmp > 0], name);
  409. /* Rebalance the tree on the way up if a new node was inserted */
  410. if (!f->versions.func)
  411. balance_tree(root);
  412. }
  413. } else {
  414. /* Allocate and insert a new node into the tree */
  415. int name_length = strlen(name);
  416. f = *root = checkasm_malloc(sizeof(CheckasmFunc) + name_length);
  417. memcpy(f->name, name, name_length + 1);
  418. }
  419. return f;
  420. }
  421. /* Perform tests and benchmarks for the specified cpu flag if supported by the host */
  422. static void check_cpu_flag(const char *name, int flag)
  423. {
  424. int old_cpu_flag = state.cpu_flag;
  425. flag |= old_cpu_flag;
  426. av_force_cpu_flags(-1);
  427. state.cpu_flag = flag & av_get_cpu_flags();
  428. av_force_cpu_flags(state.cpu_flag);
  429. if (!flag || state.cpu_flag != old_cpu_flag) {
  430. int i;
  431. state.cpu_flag_name = name;
  432. for (i = 0; tests[i].func; i++) {
  433. state.current_test_name = tests[i].name;
  434. tests[i].func();
  435. }
  436. }
  437. }
  438. /* Print the name of the current CPU flag, but only do it once */
  439. static void print_cpu_name(void)
  440. {
  441. if (state.cpu_flag_name) {
  442. color_printf(COLOR_YELLOW, "%s:\n", state.cpu_flag_name);
  443. state.cpu_flag_name = NULL;
  444. }
  445. }
  446. int main(int argc, char *argv[])
  447. {
  448. unsigned int seed;
  449. int i, ret = 0;
  450. #if ARCH_ARM && HAVE_ARMV5TE_EXTERNAL
  451. if (have_vfp(av_get_cpu_flags()) || have_neon(av_get_cpu_flags()))
  452. checkasm_checked_call = checkasm_checked_call_vfp;
  453. #endif
  454. if (!tests[0].func || !cpus[0].flag) {
  455. fprintf(stderr, "checkasm: no tests to perform\n");
  456. return 0;
  457. }
  458. if (argc > 1 && !strncmp(argv[1], "--bench", 7)) {
  459. #ifndef AV_READ_TIME
  460. fprintf(stderr, "checkasm: --bench is not supported on your system\n");
  461. return 1;
  462. #endif
  463. if (argv[1][7] == '=') {
  464. state.bench_pattern = argv[1] + 8;
  465. state.bench_pattern_len = strlen(state.bench_pattern);
  466. } else
  467. state.bench_pattern = "";
  468. argc--;
  469. argv++;
  470. }
  471. seed = (argc > 1) ? strtoul(argv[1], NULL, 10) : av_get_random_seed();
  472. fprintf(stderr, "checkasm: using random seed %u\n", seed);
  473. av_lfg_init(&checkasm_lfg, seed);
  474. check_cpu_flag(NULL, 0);
  475. for (i = 0; cpus[i].flag; i++)
  476. check_cpu_flag(cpus[i].name, cpus[i].flag);
  477. if (state.num_failed) {
  478. fprintf(stderr, "checkasm: %d of %d tests have failed\n", state.num_failed, state.num_checked);
  479. ret = 1;
  480. } else {
  481. fprintf(stderr, "checkasm: all %d tests passed\n", state.num_checked);
  482. #ifdef AV_READ_TIME
  483. if (state.bench_pattern) {
  484. state.nop_time = measure_nop_time();
  485. printf("nop: %d.%d\n", state.nop_time/10, state.nop_time%10);
  486. print_benchs(state.funcs);
  487. }
  488. #endif
  489. }
  490. destroy_func_tree(state.funcs);
  491. return ret;
  492. }
  493. /* Decide whether or not the specified function needs to be tested and
  494. * allocate/initialize data structures if needed. Returns a pointer to a
  495. * reference function if the function should be tested, otherwise NULL */
  496. void *checkasm_check_func(void *func, const char *name, ...)
  497. {
  498. char name_buf[256];
  499. void *ref = func;
  500. CheckasmFuncVersion *v;
  501. int name_length;
  502. va_list arg;
  503. va_start(arg, name);
  504. name_length = vsnprintf(name_buf, sizeof(name_buf), name, arg);
  505. va_end(arg);
  506. if (!func || name_length <= 0 || name_length >= sizeof(name_buf))
  507. return NULL;
  508. state.current_func = get_func(&state.funcs, name_buf);
  509. state.funcs->color = 1;
  510. v = &state.current_func->versions;
  511. if (v->func) {
  512. CheckasmFuncVersion *prev;
  513. do {
  514. /* Only test functions that haven't already been tested */
  515. if (v->func == func)
  516. return NULL;
  517. if (v->ok)
  518. ref = v->func;
  519. prev = v;
  520. } while ((v = v->next));
  521. v = prev->next = checkasm_malloc(sizeof(CheckasmFuncVersion));
  522. }
  523. v->func = func;
  524. v->ok = 1;
  525. v->cpu = state.cpu_flag;
  526. state.current_func_ver = v;
  527. if (state.cpu_flag)
  528. state.num_checked++;
  529. return ref;
  530. }
  531. /* Decide whether or not the current function needs to be benchmarked */
  532. int checkasm_bench_func(void)
  533. {
  534. return !state.num_failed && state.bench_pattern &&
  535. !strncmp(state.current_func->name, state.bench_pattern, state.bench_pattern_len);
  536. }
  537. /* Indicate that the current test has failed */
  538. void checkasm_fail_func(const char *msg, ...)
  539. {
  540. if (state.current_func_ver->cpu && state.current_func_ver->ok) {
  541. va_list arg;
  542. print_cpu_name();
  543. fprintf(stderr, " %s_%s (", state.current_func->name, cpu_suffix(state.current_func_ver->cpu));
  544. va_start(arg, msg);
  545. vfprintf(stderr, msg, arg);
  546. va_end(arg);
  547. fprintf(stderr, ")\n");
  548. state.current_func_ver->ok = 0;
  549. state.num_failed++;
  550. }
  551. }
  552. /* Update benchmark results of the current function */
  553. void checkasm_update_bench(int iterations, uint64_t cycles)
  554. {
  555. state.current_func_ver->iterations += iterations;
  556. state.current_func_ver->cycles += cycles;
  557. }
  558. /* Print the outcome of all tests performed since the last time this function was called */
  559. void checkasm_report(const char *name, ...)
  560. {
  561. static int prev_checked, prev_failed, max_length;
  562. if (state.num_checked > prev_checked) {
  563. int pad_length = max_length + 4;
  564. va_list arg;
  565. print_cpu_name();
  566. pad_length -= fprintf(stderr, " - %s.", state.current_test_name);
  567. va_start(arg, name);
  568. pad_length -= vfprintf(stderr, name, arg);
  569. va_end(arg);
  570. fprintf(stderr, "%*c", FFMAX(pad_length, 0) + 2, '[');
  571. if (state.num_failed == prev_failed)
  572. color_printf(COLOR_GREEN, "OK");
  573. else
  574. color_printf(COLOR_RED, "FAILED");
  575. fprintf(stderr, "]\n");
  576. prev_checked = state.num_checked;
  577. prev_failed = state.num_failed;
  578. } else if (!state.cpu_flag) {
  579. /* Calculate the amount of padding required to make the output vertically aligned */
  580. int length = strlen(state.current_test_name);
  581. va_list arg;
  582. va_start(arg, name);
  583. length += vsnprintf(NULL, 0, name, arg);
  584. va_end(arg);
  585. if (length > max_length)
  586. max_length = length;
  587. }
  588. }