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 "InstrProfilingUtil.h"
24
25#include <errno.h>
26#include <fcntl.h>
27#include <stdio.h>
28#include <stdlib.h>
29#include <string.h>
30
31#if defined(_WIN32)
32#include "WindowsMMap.h"
33#else
34#include <sys/mman.h>
35#include <sys/file.h>
36#endif
37
38#if defined(__FreeBSD__) && defined(__i386__)
39#define I386_FREEBSD 1
40#else
41#define I386_FREEBSD 0
42#endif
43
44#if !defined(_MSC_VER) && !I386_FREEBSD
45#include <stdint.h>
46#endif
47
48#if defined(_MSC_VER)
49typedef unsigned char uint8_t;
50typedef unsigned int uint32_t;
51typedef unsigned long long uint64_t;
52#elif I386_FREEBSD
53/* System headers define 'size_t' incorrectly on x64 FreeBSD (prior to
54 * FreeBSD 10, r232261) when compiled in 32-bit mode.
55 */
56typedef unsigned char uint8_t;
57typedef unsigned int uint32_t;
58typedef unsigned long long uint64_t;
59#endif
60
61/* #define DEBUG_GCDAPROFILING */
62
63/*
64 * --- GCOV file format I/O primitives ---
65 */
66
67/*
68 * The current file name we're outputting. Used primarily for error logging.
69 */
70static char *filename = NULL;
71
72/*
73 * The current file we're outputting.
74 */
75static FILE *output_file = NULL;
76
77/*
78 * Buffer that we write things into.
79 */
80#define WRITE_BUFFER_SIZE (128 * 1024)
81static char *write_buffer = NULL;
82static uint64_t cur_buffer_size = 0;
83static uint64_t cur_pos = 0;
84static uint64_t file_size = 0;
85static int new_file = 0;
86static int fd = -1;
87
88/*
89 * A list of functions to write out the data.
90 */
91typedef void (*writeout_fn)();
92
93struct writeout_fn_node {
94  writeout_fn fn;
95  struct writeout_fn_node *next;
96};
97
98static struct writeout_fn_node *writeout_fn_head = NULL;
99static struct writeout_fn_node *writeout_fn_tail = NULL;
100
101/*
102 *  A list of flush functions that our __gcov_flush() function should call.
103 */
104typedef void (*flush_fn)();
105
106struct flush_fn_node {
107  flush_fn fn;
108  struct flush_fn_node *next;
109};
110
111static struct flush_fn_node *flush_fn_head = NULL;
112static struct flush_fn_node *flush_fn_tail = NULL;
113
114static void resize_write_buffer(uint64_t size) {
115  if (!new_file) return;
116  size += cur_pos;
117  if (size <= cur_buffer_size) return;
118  size = (size - 1) / WRITE_BUFFER_SIZE + 1;
119  size *= WRITE_BUFFER_SIZE;
120  write_buffer = realloc(write_buffer, size);
121  cur_buffer_size = size;
122}
123
124static void write_bytes(const char *s, size_t len) {
125  resize_write_buffer(len);
126  memcpy(&write_buffer[cur_pos], s, len);
127  cur_pos += len;
128}
129
130static void write_32bit_value(uint32_t i) {
131  write_bytes((char*)&i, 4);
132}
133
134static void write_64bit_value(uint64_t i) {
135  write_bytes((char*)&i, 8);
136}
137
138static uint32_t length_of_string(const char *s) {
139  return (strlen(s) / 4) + 1;
140}
141
142static void write_string(const char *s) {
143  uint32_t len = length_of_string(s);
144  write_32bit_value(len);
145  write_bytes(s, strlen(s));
146  write_bytes("\0\0\0\0", 4 - (strlen(s) % 4));
147}
148
149static uint32_t read_32bit_value() {
150  uint32_t val;
151
152  if (new_file)
153    return (uint32_t)-1;
154
155  val = *(uint32_t*)&write_buffer[cur_pos];
156  cur_pos += 4;
157  return val;
158}
159
160static uint64_t read_64bit_value() {
161  uint64_t val;
162
163  if (new_file)
164    return (uint64_t)-1;
165
166  val = *(uint64_t*)&write_buffer[cur_pos];
167  cur_pos += 8;
168  return val;
169}
170
171static char *mangle_filename(const char *orig_filename) {
172  char *new_filename;
173  size_t filename_len, prefix_len;
174  int prefix_strip;
175  int level = 0;
176  const char *fname, *ptr;
177  const char *prefix = getenv("GCOV_PREFIX");
178  const char *prefix_strip_str = getenv("GCOV_PREFIX_STRIP");
179
180  if (prefix == NULL || prefix[0] == '\0')
181    return strdup(orig_filename);
182
183  if (prefix_strip_str) {
184    prefix_strip = atoi(prefix_strip_str);
185
186    /* Negative GCOV_PREFIX_STRIP values are ignored */
187    if (prefix_strip < 0)
188      prefix_strip = 0;
189  } else {
190    prefix_strip = 0;
191  }
192
193  fname = orig_filename;
194  for (level = 0, ptr = fname + 1; level < prefix_strip; ++ptr) {
195    if (*ptr == '\0')
196      break;
197    if (*ptr != '/')
198      continue;
199    fname = ptr;
200    ++level;
201  }
202
203  filename_len = strlen(fname);
204  prefix_len = strlen(prefix);
205  new_filename = malloc(prefix_len + 1 + filename_len + 1);
206  memcpy(new_filename, prefix, prefix_len);
207
208  if (prefix[prefix_len - 1] != '/')
209    new_filename[prefix_len++] = '/';
210  memcpy(new_filename + prefix_len, fname, filename_len + 1);
211
212  return new_filename;
213}
214
215static int map_file() {
216  fseek(output_file, 0L, SEEK_END);
217  file_size = ftell(output_file);
218
219  /* A size of 0 is invalid to `mmap'. Return a fail here, but don't issue an
220   * error message because it should "just work" for the user. */
221  if (file_size == 0)
222    return -1;
223
224  write_buffer = mmap(0, file_size, PROT_READ | PROT_WRITE,
225                      MAP_FILE | MAP_SHARED, fd, 0);
226  if (write_buffer == (void *)-1) {
227    int errnum = errno;
228    fprintf(stderr, "profiling: %s: cannot map: %s\n", filename,
229            strerror(errnum));
230    return -1;
231  }
232  return 0;
233}
234
235static void unmap_file() {
236  if (msync(write_buffer, file_size, MS_SYNC) == -1) {
237    int errnum = errno;
238    fprintf(stderr, "profiling: %s: cannot msync: %s\n", filename,
239            strerror(errnum));
240  }
241
242  /* We explicitly ignore errors from unmapping because at this point the data
243   * is written and we don't care.
244   */
245  (void)munmap(write_buffer, file_size);
246  write_buffer = NULL;
247  file_size = 0;
248}
249
250/*
251 * --- LLVM line counter API ---
252 */
253
254/* A file in this case is a translation unit. Each .o file built with line
255 * profiling enabled will emit to a different file. Only one file may be
256 * started at a time.
257 */
258void llvm_gcda_start_file(const char *orig_filename, const char version[4],
259                          uint32_t checksum) {
260  const char *mode = "r+b";
261  filename = mangle_filename(orig_filename);
262
263  /* Try just opening the file. */
264  new_file = 0;
265  fd = open(filename, O_RDWR);
266
267  if (fd == -1) {
268    /* Try opening the file, creating it if necessary. */
269    new_file = 1;
270    mode = "w+b";
271    fd = open(filename, O_RDWR | O_CREAT, 0644);
272    if (fd == -1) {
273      /* Try creating the directories first then opening the file. */
274      __llvm_profile_recursive_mkdir(filename);
275      fd = open(filename, O_RDWR | O_CREAT, 0644);
276      if (fd == -1) {
277        /* Bah! It's hopeless. */
278        int errnum = errno;
279        fprintf(stderr, "profiling: %s: cannot open: %s\n", filename,
280                strerror(errnum));
281        return;
282      }
283    }
284  }
285
286  /* Try to flock the file to serialize concurrent processes writing out to the
287   * same GCDA. This can fail if the filesystem doesn't support it, but in that
288   * case we'll just carry on with the old racy behaviour and hope for the best.
289   */
290  flock(fd, LOCK_EX);
291  output_file = fdopen(fd, mode);
292
293  /* Initialize the write buffer. */
294  write_buffer = NULL;
295  cur_buffer_size = 0;
296  cur_pos = 0;
297
298  if (new_file) {
299    resize_write_buffer(WRITE_BUFFER_SIZE);
300    memset(write_buffer, 0, WRITE_BUFFER_SIZE);
301  } else {
302    if (map_file() == -1) {
303      /* mmap failed, try to recover by clobbering */
304      new_file = 1;
305      write_buffer = NULL;
306      cur_buffer_size = 0;
307      resize_write_buffer(WRITE_BUFFER_SIZE);
308      memset(write_buffer, 0, WRITE_BUFFER_SIZE);
309    }
310  }
311
312  /* gcda file, version, stamp checksum. */
313  write_bytes("adcg", 4);
314  write_bytes(version, 4);
315  write_32bit_value(checksum);
316
317#ifdef DEBUG_GCDAPROFILING
318  fprintf(stderr, "llvmgcda: [%s]\n", orig_filename);
319#endif
320}
321
322/* Given an array of pointers to counters (counters), increment the n-th one,
323 * where we're also given a pointer to n (predecessor).
324 */
325void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
326                                          uint64_t **counters) {
327  uint64_t *counter;
328  uint32_t pred;
329
330  pred = *predecessor;
331  if (pred == 0xffffffff)
332    return;
333  counter = counters[pred];
334
335  /* Don't crash if the pred# is out of sync. This can happen due to threads,
336     or because of a TODO in GCOVProfiling.cpp buildEdgeLookupTable(). */
337  if (counter)
338    ++*counter;
339#ifdef DEBUG_GCDAPROFILING
340  else
341    fprintf(stderr,
342            "llvmgcda: increment_indirect_counter counters=%08llx, pred=%u\n",
343            *counter, *predecessor);
344#endif
345}
346
347void llvm_gcda_emit_function(uint32_t ident, const char *function_name,
348                             uint32_t func_checksum, uint8_t use_extra_checksum,
349                             uint32_t cfg_checksum) {
350  uint32_t len = 2;
351
352  if (use_extra_checksum)
353    len++;
354#ifdef DEBUG_GCDAPROFILING
355  fprintf(stderr, "llvmgcda: function id=0x%08x name=%s\n", ident,
356          function_name ? function_name : "NULL");
357#endif
358  if (!output_file) return;
359
360  /* function tag */
361  write_bytes("\0\0\0\1", 4);
362  if (function_name)
363    len += 1 + length_of_string(function_name);
364  write_32bit_value(len);
365  write_32bit_value(ident);
366  write_32bit_value(func_checksum);
367  if (use_extra_checksum)
368    write_32bit_value(cfg_checksum);
369  if (function_name)
370    write_string(function_name);
371}
372
373void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
374  uint32_t i;
375  uint64_t *old_ctrs = NULL;
376  uint32_t val = 0;
377  uint64_t save_cur_pos = cur_pos;
378
379  if (!output_file) return;
380
381  val = read_32bit_value();
382
383  if (val != (uint32_t)-1) {
384    /* There are counters present in the file. Merge them. */
385    if (val != 0x01a10000) {
386      fprintf(stderr, "profiling: %s: cannot merge previous GCDA file: "
387                      "corrupt arc tag (0x%08x)\n",
388              filename, val);
389      return;
390    }
391
392    val = read_32bit_value();
393    if (val == (uint32_t)-1 || val / 2 != num_counters) {
394      fprintf(stderr, "profiling: %s: cannot merge previous GCDA file: "
395                      "mismatched number of counters (%d)\n",
396              filename, val);
397      return;
398    }
399
400    old_ctrs = malloc(sizeof(uint64_t) * num_counters);
401    for (i = 0; i < num_counters; ++i)
402      old_ctrs[i] = read_64bit_value();
403  }
404
405  cur_pos = save_cur_pos;
406
407  /* Counter #1 (arcs) tag */
408  write_bytes("\0\0\xa1\1", 4);
409  write_32bit_value(num_counters * 2);
410  for (i = 0; i < num_counters; ++i) {
411    counters[i] += (old_ctrs ? old_ctrs[i] : 0);
412    write_64bit_value(counters[i]);
413  }
414
415  free(old_ctrs);
416
417#ifdef DEBUG_GCDAPROFILING
418  fprintf(stderr, "llvmgcda:   %u arcs\n", num_counters);
419  for (i = 0; i < num_counters; ++i)
420    fprintf(stderr, "llvmgcda:   %llu\n", (unsigned long long)counters[i]);
421#endif
422}
423
424void llvm_gcda_summary_info() {
425  const uint32_t obj_summary_len = 9; /* Length for gcov compatibility. */
426  uint32_t i;
427  uint32_t runs = 1;
428  uint32_t val = 0;
429  uint64_t save_cur_pos = cur_pos;
430
431  if (!output_file) return;
432
433  val = read_32bit_value();
434
435  if (val != (uint32_t)-1) {
436    /* There are counters present in the file. Merge them. */
437    if (val != 0xa1000000) {
438      fprintf(stderr, "profiling: %s: cannot merge previous run count: "
439                      "corrupt object tag (0x%08x)\n",
440              filename, val);
441      return;
442    }
443
444    val = read_32bit_value(); /* length */
445    if (val != obj_summary_len) {
446      fprintf(stderr, "profiling: %s: cannot merge previous run count: "
447                      "mismatched object length (%d)\n",
448              filename, val);
449      return;
450    }
451
452    read_32bit_value(); /* checksum, unused */
453    read_32bit_value(); /* num, unused */
454    runs += read_32bit_value(); /* Add previous run count to new counter. */
455  }
456
457  cur_pos = save_cur_pos;
458
459  /* Object summary tag */
460  write_bytes("\0\0\0\xa1", 4);
461  write_32bit_value(obj_summary_len);
462  write_32bit_value(0); /* checksum, unused */
463  write_32bit_value(0); /* num, unused */
464  write_32bit_value(runs);
465  for (i = 3; i < obj_summary_len; ++i)
466    write_32bit_value(0);
467
468  /* Program summary tag */
469  write_bytes("\0\0\0\xa3", 4); /* tag indicates 1 program */
470  write_32bit_value(0); /* 0 length */
471
472#ifdef DEBUG_GCDAPROFILING
473  fprintf(stderr, "llvmgcda:   %u runs\n", runs);
474#endif
475}
476
477void llvm_gcda_end_file() {
478  /* Write out EOF record. */
479  if (output_file) {
480    write_bytes("\0\0\0\0\0\0\0\0", 8);
481
482    if (new_file) {
483      fwrite(write_buffer, cur_pos, 1, output_file);
484      free(write_buffer);
485    } else {
486      unmap_file();
487    }
488
489    flock(fd, LOCK_UN);
490    fclose(output_file);
491    output_file = NULL;
492    write_buffer = NULL;
493  }
494  free(filename);
495
496#ifdef DEBUG_GCDAPROFILING
497  fprintf(stderr, "llvmgcda: -----\n");
498#endif
499}
500
501void llvm_register_writeout_function(writeout_fn fn) {
502  struct writeout_fn_node *new_node = malloc(sizeof(struct writeout_fn_node));
503  new_node->fn = fn;
504  new_node->next = NULL;
505
506  if (!writeout_fn_head) {
507    writeout_fn_head = writeout_fn_tail = new_node;
508  } else {
509    writeout_fn_tail->next = new_node;
510    writeout_fn_tail = new_node;
511  }
512}
513
514void llvm_writeout_files(void) {
515  struct writeout_fn_node *curr = writeout_fn_head;
516
517  while (curr) {
518    curr->fn();
519    curr = curr->next;
520  }
521}
522
523void llvm_delete_writeout_function_list(void) {
524  while (writeout_fn_head) {
525    struct writeout_fn_node *node = writeout_fn_head;
526    writeout_fn_head = writeout_fn_head->next;
527    free(node);
528  }
529
530  writeout_fn_head = writeout_fn_tail = NULL;
531}
532
533void llvm_register_flush_function(flush_fn fn) {
534  struct flush_fn_node *new_node = malloc(sizeof(struct flush_fn_node));
535  new_node->fn = fn;
536  new_node->next = NULL;
537
538  if (!flush_fn_head) {
539    flush_fn_head = flush_fn_tail = new_node;
540  } else {
541    flush_fn_tail->next = new_node;
542    flush_fn_tail = new_node;
543  }
544}
545
546void __gcov_flush() {
547  struct flush_fn_node *curr = flush_fn_head;
548
549  while (curr) {
550    curr->fn();
551    curr = curr->next;
552  }
553}
554
555void llvm_delete_flush_function_list(void) {
556  while (flush_fn_head) {
557    struct flush_fn_node *node = flush_fn_head;
558    flush_fn_head = flush_fn_head->next;
559    free(node);
560  }
561
562  flush_fn_head = flush_fn_tail = NULL;
563}
564
565void llvm_gcov_init(writeout_fn wfn, flush_fn ffn) {
566  static int atexit_ran = 0;
567
568  if (wfn)
569    llvm_register_writeout_function(wfn);
570
571  if (ffn)
572    llvm_register_flush_function(ffn);
573
574  if (atexit_ran == 0) {
575    atexit_ran = 1;
576
577    /* Make sure we write out the data and delete the data structures. */
578    atexit(llvm_delete_flush_function_list);
579    atexit(llvm_delete_writeout_function_list);
580    atexit(llvm_writeout_files);
581  }
582}
583