1/*===- GCDAProfiling.c - Support library for GCDA file emission -----------===*\
2|*
3|*                     The LLVM Compiler Infrastructure
4|*
5|* This file is distributed under the University of Illinois Open Source
6|* License. See LICENSE.TXT for details.
7|*
8|*===----------------------------------------------------------------------===*|
9|*
10|* This file implements the call back routines for the gcov profiling
11|* instrumentation pass. Link against this library when running code through
12|* the -insert-gcov-profiling LLVM pass.
13|*
14|* We emit files in a corrupt version of GCOV's "gcda" file format. These files
15|* are only close enough that LCOV will happily parse them. Anything that lcov
16|* ignores is missing.
17|*
18|* TODO: gcov is multi-process safe by having each exit open the existing file
19|* and append to it. We'd like to achieve that and be thread-safe too.
20|*
21\*===----------------------------------------------------------------------===*/
22
23#include <errno.h>
24#include <fcntl.h>
25#include <stdio.h>
26#include <stdlib.h>
27#include <string.h>
28#include <sys/mman.h>
29#ifdef _WIN32
30#include <direct.h>
31#endif
32
33#define I386_FREEBSD (defined(__FreeBSD__) && defined(__i386__))
34
35#if !I386_FREEBSD
36#include <sys/stat.h>
37#include <sys/types.h>
38#endif
39
40#if !defined(_MSC_VER) && !I386_FREEBSD
41#include <stdint.h>
42#endif
43
44#if defined(_MSC_VER)
45typedef unsigned int uint32_t;
46typedef unsigned long long uint64_t;
47#elif I386_FREEBSD
48/* System headers define 'size_t' incorrectly on x64 FreeBSD (prior to
49 * FreeBSD 10, r232261) when compiled in 32-bit mode.
50 */
51typedef unsigned char uint8_t;
52typedef unsigned int uint32_t;
53typedef unsigned long long uint64_t;
54int mkdir(const char*, unsigned short);
55#endif
56
57/* #define DEBUG_GCDAPROFILING */
58
59/*
60 * --- GCOV file format I/O primitives ---
61 */
62
63/*
64 * The current file name we're outputting. Used primarily for error logging.
65 */
66static char *filename = NULL;
67
68/*
69 * The current file we're outputting.
70 */
71static FILE *output_file = NULL;
72
73/*
74 * Buffer that we write things into.
75 */
76#define WRITE_BUFFER_SIZE (128 * 1024)
77static char *write_buffer = NULL;
78static uint64_t cur_buffer_size = 0;
79static uint64_t cur_pos = 0;
80static uint64_t file_size = 0;
81static int new_file = 0;
82static int fd = -1;
83
84/*
85 * A list of functions to write out the data.
86 */
87typedef void (*writeout_fn)();
88
89struct writeout_fn_node {
90  writeout_fn fn;
91  struct writeout_fn_node *next;
92};
93
94static struct writeout_fn_node *writeout_fn_head = NULL;
95static struct writeout_fn_node *writeout_fn_tail = NULL;
96
97/*
98 *  A list of flush functions that our __gcov_flush() function should call.
99 */
100typedef void (*flush_fn)();
101
102struct flush_fn_node {
103  flush_fn fn;
104  struct flush_fn_node *next;
105};
106
107static struct flush_fn_node *flush_fn_head = NULL;
108static struct flush_fn_node *flush_fn_tail = NULL;
109
110static void resize_write_buffer(uint64_t size) {
111  if (!new_file) return;
112  size += cur_pos;
113  if (size <= cur_buffer_size) return;
114  size = (size - 1) / WRITE_BUFFER_SIZE + 1;
115  size *= WRITE_BUFFER_SIZE;
116  write_buffer = realloc(write_buffer, size);
117  cur_buffer_size = size;
118}
119
120static void write_bytes(const char *s, size_t len) {
121  resize_write_buffer(len);
122  memcpy(&write_buffer[cur_pos], s, len);
123  cur_pos += len;
124}
125
126static void write_32bit_value(uint32_t i) {
127  write_bytes((char*)&i, 4);
128}
129
130static void write_64bit_value(uint64_t i) {
131  write_bytes((char*)&i, 8);
132}
133
134static uint32_t length_of_string(const char *s) {
135  return (strlen(s) / 4) + 1;
136}
137
138static void write_string(const char *s) {
139  uint32_t len = length_of_string(s);
140  write_32bit_value(len);
141  write_bytes(s, strlen(s));
142  write_bytes("\0\0\0\0", 4 - (strlen(s) % 4));
143}
144
145static uint32_t read_32bit_value() {
146  uint32_t val;
147
148  if (new_file)
149    return (uint32_t)-1;
150
151  val = *(uint32_t*)&write_buffer[cur_pos];
152  cur_pos += 4;
153  return val;
154}
155
156static uint64_t read_64bit_value() {
157  uint64_t val;
158
159  if (new_file)
160    return (uint64_t)-1;
161
162  val = *(uint64_t*)&write_buffer[cur_pos];
163  cur_pos += 8;
164  return val;
165}
166
167static char *mangle_filename(const char *orig_filename) {
168  char *new_filename;
169  size_t filename_len, prefix_len;
170  int prefix_strip;
171  int level = 0;
172  const char *fname, *ptr;
173  const char *prefix = getenv("GCOV_PREFIX");
174  const char *prefix_strip_str = getenv("GCOV_PREFIX_STRIP");
175
176  if (prefix == NULL || prefix[0] == '\0')
177    return strdup(orig_filename);
178
179  if (prefix_strip_str) {
180    prefix_strip = atoi(prefix_strip_str);
181
182    /* Negative GCOV_PREFIX_STRIP values are ignored */
183    if (prefix_strip < 0)
184      prefix_strip = 0;
185  } else {
186    prefix_strip = 0;
187  }
188
189  fname = orig_filename;
190  for (level = 0, ptr = fname + 1; level < prefix_strip; ++ptr) {
191    if (*ptr == '\0')
192      break;
193    if (*ptr != '/')
194      continue;
195    fname = ptr;
196    ++level;
197  }
198
199  filename_len = strlen(fname);
200  prefix_len = strlen(prefix);
201  new_filename = malloc(prefix_len + 1 + filename_len + 1);
202  memcpy(new_filename, prefix, prefix_len);
203
204  if (prefix[prefix_len - 1] != '/')
205    new_filename[prefix_len++] = '/';
206  memcpy(new_filename + prefix_len, fname, filename_len + 1);
207
208  return new_filename;
209}
210
211static void recursive_mkdir(char *path) {
212  int i;
213
214  for (i = 1; path[i] != '\0'; ++i) {
215    if (path[i] != '/') continue;
216    path[i] = '\0';
217#ifdef _WIN32
218    _mkdir(path);
219#else
220    mkdir(path, 0755);  /* Some of these will fail, ignore it. */
221#endif
222    path[i] = '/';
223  }
224}
225
226static int map_file() {
227  fseek(output_file, 0L, SEEK_END);
228  file_size = ftell(output_file);
229
230  /* A size of 0 is invalid to `mmap'. Return a fail here, but don't issue an
231   * error message because it should "just work" for the user. */
232  if (file_size == 0)
233    return -1;
234
235  write_buffer = mmap(0, file_size, PROT_READ | PROT_WRITE,
236                      MAP_FILE | MAP_SHARED, fd, 0);
237  if (write_buffer == (void *)-1) {
238    int errnum = errno;
239    fprintf(stderr, "profiling: %s: cannot map: %s\n", filename,
240            strerror(errnum));
241    return -1;
242  }
243  return 0;
244}
245
246static void unmap_file() {
247  if (msync(write_buffer, file_size, MS_SYNC) == -1) {
248    int errnum = errno;
249    fprintf(stderr, "profiling: %s: cannot msync: %s\n", filename,
250            strerror(errnum));
251  }
252
253  /* We explicitly ignore errors from unmapping because at this point the data
254   * is written and we don't care.
255   */
256  (void)munmap(write_buffer, file_size);
257  write_buffer = NULL;
258  file_size = 0;
259}
260
261/*
262 * --- LLVM line counter API ---
263 */
264
265/* A file in this case is a translation unit. Each .o file built with line
266 * profiling enabled will emit to a different file. Only one file may be
267 * started at a time.
268 */
269void llvm_gcda_start_file(const char *orig_filename, const char version[4],
270                          uint32_t checksum) {
271  const char *mode = "r+b";
272  filename = mangle_filename(orig_filename);
273
274  /* Try just opening the file. */
275  new_file = 0;
276  fd = open(filename, O_RDWR);
277
278  if (fd == -1) {
279    /* Try opening the file, creating it if necessary. */
280    new_file = 1;
281    mode = "w+b";
282    fd = open(filename, O_RDWR | O_CREAT, 0644);
283    if (fd == -1) {
284      /* Try creating the directories first then opening the file. */
285      recursive_mkdir(filename);
286      fd = open(filename, O_RDWR | O_CREAT, 0644);
287      if (fd == -1) {
288        /* Bah! It's hopeless. */
289        int errnum = errno;
290        fprintf(stderr, "profiling: %s: cannot open: %s\n", filename,
291                strerror(errnum));
292        return;
293      }
294    }
295  }
296
297  output_file = fdopen(fd, mode);
298
299  /* Initialize the write buffer. */
300  write_buffer = NULL;
301  cur_buffer_size = 0;
302  cur_pos = 0;
303
304  if (new_file) {
305    resize_write_buffer(WRITE_BUFFER_SIZE);
306    memset(write_buffer, 0, WRITE_BUFFER_SIZE);
307  } else {
308    if (map_file() == -1) {
309      /* mmap failed, try to recover by clobbering */
310      new_file = 1;
311      write_buffer = NULL;
312      cur_buffer_size = 0;
313      resize_write_buffer(WRITE_BUFFER_SIZE);
314      memset(write_buffer, 0, WRITE_BUFFER_SIZE);
315    }
316  }
317
318  /* gcda file, version, stamp checksum. */
319  write_bytes("adcg", 4);
320  write_bytes(version, 4);
321  write_32bit_value(checksum);
322
323#ifdef DEBUG_GCDAPROFILING
324  fprintf(stderr, "llvmgcda: [%s]\n", orig_filename);
325#endif
326}
327
328/* Given an array of pointers to counters (counters), increment the n-th one,
329 * where we're also given a pointer to n (predecessor).
330 */
331void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
332                                          uint64_t **counters) {
333  uint64_t *counter;
334  uint32_t pred;
335
336  pred = *predecessor;
337  if (pred == 0xffffffff)
338    return;
339  counter = counters[pred];
340
341  /* Don't crash if the pred# is out of sync. This can happen due to threads,
342     or because of a TODO in GCOVProfiling.cpp buildEdgeLookupTable(). */
343  if (counter)
344    ++*counter;
345#ifdef DEBUG_GCDAPROFILING
346  else
347    fprintf(stderr,
348            "llvmgcda: increment_indirect_counter counters=%08llx, pred=%u\n",
349            *counter, *predecessor);
350#endif
351}
352
353void llvm_gcda_emit_function(uint32_t ident, const char *function_name,
354                             uint32_t func_checksum, uint8_t use_extra_checksum,
355                             uint32_t cfg_checksum) {
356  uint32_t len = 2;
357
358  if (use_extra_checksum)
359    len++;
360#ifdef DEBUG_GCDAPROFILING
361  fprintf(stderr, "llvmgcda: function id=0x%08x name=%s\n", ident,
362          function_name ? function_name : "NULL");
363#endif
364  if (!output_file) return;
365
366  /* function tag */
367  write_bytes("\0\0\0\1", 4);
368  if (function_name)
369    len += 1 + length_of_string(function_name);
370  write_32bit_value(len);
371  write_32bit_value(ident);
372  write_32bit_value(func_checksum);
373  if (use_extra_checksum)
374    write_32bit_value(cfg_checksum);
375  if (function_name)
376    write_string(function_name);
377}
378
379void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
380  uint32_t i;
381  uint64_t *old_ctrs = NULL;
382  uint32_t val = 0;
383  uint64_t save_cur_pos = cur_pos;
384
385  if (!output_file) return;
386
387  val = read_32bit_value();
388
389  if (val != (uint32_t)-1) {
390    /* There are counters present in the file. Merge them. */
391    if (val != 0x01a10000) {
392      fprintf(stderr, "profiling:invalid arc tag (0x%08x)\n", val);
393      return;
394    }
395
396    val = read_32bit_value();
397    if (val == (uint32_t)-1 || val / 2 != num_counters) {
398      fprintf(stderr, "profiling:invalid number of counters (%d)\n", val);
399      return;
400    }
401
402    old_ctrs = malloc(sizeof(uint64_t) * num_counters);
403    for (i = 0; i < num_counters; ++i)
404      old_ctrs[i] = read_64bit_value();
405  }
406
407  cur_pos = save_cur_pos;
408
409  /* Counter #1 (arcs) tag */
410  write_bytes("\0\0\xa1\1", 4);
411  write_32bit_value(num_counters * 2);
412  for (i = 0; i < num_counters; ++i) {
413    counters[i] += (old_ctrs ? old_ctrs[i] : 0);
414    write_64bit_value(counters[i]);
415  }
416
417  free(old_ctrs);
418
419#ifdef DEBUG_GCDAPROFILING
420  fprintf(stderr, "llvmgcda:   %u arcs\n", num_counters);
421  for (i = 0; i < num_counters; ++i)
422    fprintf(stderr, "llvmgcda:   %llu\n", (unsigned long long)counters[i]);
423#endif
424}
425
426void llvm_gcda_summary_info() {
427  const uint32_t obj_summary_len = 9; /* Length for gcov compatibility. */
428  uint32_t i;
429  uint32_t runs = 1;
430  uint32_t val = 0;
431  uint64_t save_cur_pos = cur_pos;
432
433  if (!output_file) return;
434
435  val = read_32bit_value();
436
437  if (val != (uint32_t)-1) {
438    /* There are counters present in the file. Merge them. */
439    if (val != 0xa1000000) {
440      fprintf(stderr, "profiling:invalid object tag (0x%08x)\n", val);
441      return;
442    }
443
444    val = read_32bit_value(); /* length */
445    if (val != obj_summary_len) {
446      fprintf(stderr, "profiling:invalid object length (%d)\n", val);
447      return;
448    }
449
450    read_32bit_value(); /* checksum, unused */
451    read_32bit_value(); /* num, unused */
452    runs += read_32bit_value(); /* Add previous run count to new counter. */
453  }
454
455  cur_pos = save_cur_pos;
456
457  /* Object summary tag */
458  write_bytes("\0\0\0\xa1", 4);
459  write_32bit_value(obj_summary_len);
460  write_32bit_value(0); /* checksum, unused */
461  write_32bit_value(0); /* num, unused */
462  write_32bit_value(runs);
463  for (i = 3; i < obj_summary_len; ++i)
464    write_32bit_value(0);
465
466  /* Program summary tag */
467  write_bytes("\0\0\0\xa3", 4); /* tag indicates 1 program */
468  write_32bit_value(0); /* 0 length */
469
470#ifdef DEBUG_GCDAPROFILING
471  fprintf(stderr, "llvmgcda:   %u runs\n", runs);
472#endif
473}
474
475void llvm_gcda_end_file() {
476  /* Write out EOF record. */
477  if (output_file) {
478    write_bytes("\0\0\0\0\0\0\0\0", 8);
479
480    if (new_file) {
481      fwrite(write_buffer, cur_pos, 1, output_file);
482      free(write_buffer);
483    } else {
484      unmap_file();
485    }
486
487    fclose(output_file);
488    output_file = NULL;
489    write_buffer = NULL;
490  }
491  free(filename);
492
493#ifdef DEBUG_GCDAPROFILING
494  fprintf(stderr, "llvmgcda: -----\n");
495#endif
496}
497
498void llvm_register_writeout_function(writeout_fn fn) {
499  struct writeout_fn_node *new_node = malloc(sizeof(struct writeout_fn_node));
500  new_node->fn = fn;
501  new_node->next = NULL;
502
503  if (!writeout_fn_head) {
504    writeout_fn_head = writeout_fn_tail = new_node;
505  } else {
506    writeout_fn_tail->next = new_node;
507    writeout_fn_tail = new_node;
508  }
509}
510
511void llvm_writeout_files() {
512  struct writeout_fn_node *curr = writeout_fn_head;
513
514  while (curr) {
515    curr->fn();
516    curr = curr->next;
517  }
518}
519
520void llvm_delete_writeout_function_list() {
521  while (writeout_fn_head) {
522    struct writeout_fn_node *node = writeout_fn_head;
523    writeout_fn_head = writeout_fn_head->next;
524    free(node);
525  }
526
527  writeout_fn_head = writeout_fn_tail = NULL;
528}
529
530void llvm_register_flush_function(flush_fn fn) {
531  struct flush_fn_node *new_node = malloc(sizeof(struct flush_fn_node));
532  new_node->fn = fn;
533  new_node->next = NULL;
534
535  if (!flush_fn_head) {
536    flush_fn_head = flush_fn_tail = new_node;
537  } else {
538    flush_fn_tail->next = new_node;
539    flush_fn_tail = new_node;
540  }
541}
542
543void __gcov_flush() {
544  struct flush_fn_node *curr = flush_fn_head;
545
546  while (curr) {
547    curr->fn();
548    curr = curr->next;
549  }
550}
551
552void llvm_delete_flush_function_list() {
553  while (flush_fn_head) {
554    struct flush_fn_node *node = flush_fn_head;
555    flush_fn_head = flush_fn_head->next;
556    free(node);
557  }
558
559  flush_fn_head = flush_fn_tail = NULL;
560}
561
562void llvm_gcov_init(writeout_fn wfn, flush_fn ffn) {
563  static int atexit_ran = 0;
564
565  if (wfn)
566    llvm_register_writeout_function(wfn);
567
568  if (ffn)
569    llvm_register_flush_function(ffn);
570
571  if (atexit_ran == 0) {
572    atexit_ran = 1;
573
574    /* Make sure we write out the data and delete the data structures. */
575    atexit(llvm_delete_flush_function_list);
576    atexit(llvm_delete_writeout_function_list);
577    atexit(llvm_writeout_files);
578  }
579}
580