GCDAProfiling.c revision 7bb5d49a6402c5a1d20911e6992ebb7e9e4468c4 
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/stat.h>
29#include <sys/mman.h>
30#include <sys/types.h>
31#ifdef _WIN32
32#include <direct.h>
33#endif
34
35#ifndef _MSC_VER
36#include <stdint.h>
37#else
38typedef unsigned int uint32_t;
39typedef unsigned int uint64_t;
40#endif
41
42/* #define DEBUG_GCDAPROFILING */
43
44/*
45 * --- GCOV file format I/O primitives ---
46 */
47
48/*
49 * The current file name we're outputting. Used primarily for error logging.
50 */
51static char *filename = NULL;
52
53/*
54 * The current file we're outputting.
55 */
56static FILE *output_file = NULL;
57
58/*
59 * Buffer that we write things into.
60 */
61#define WRITE_BUFFER_SIZE (128 * 1024)
62static char *write_buffer = NULL;
63static uint64_t cur_buffer_size = 0;
64static uint64_t cur_pos = 0;
65static uint64_t file_size = 0;
66static int new_file = 0;
67static int fd = -1;
68
69/*
70 * A list of functions to write out the data.
71 */
72typedef void (*writeout_fn)();
73
74struct writeout_fn_node {
75  writeout_fn fn;
76  struct writeout_fn_node *next;
77};
78
79static struct writeout_fn_node *writeout_fn_head = NULL;
80static struct writeout_fn_node *writeout_fn_tail = NULL;
81
82/*
83 *  A list of flush functions that our __gcov_flush() function should call.
84 */
85typedef void (*flush_fn)();
86
87struct flush_fn_node {
88  flush_fn fn;
89  struct flush_fn_node *next;
90};
91
92static struct flush_fn_node *flush_fn_head = NULL;
93static struct flush_fn_node *flush_fn_tail = NULL;
94
95static void resize_write_buffer(uint64_t size) {
96  if (!new_file) return;
97  size += cur_pos;
98  if (size <= cur_buffer_size) return;
99  size = (size - 1) / WRITE_BUFFER_SIZE + 1;
100  size *= WRITE_BUFFER_SIZE;
101  write_buffer = realloc(write_buffer, size);
102  cur_buffer_size = size;
103}
104
105static void write_bytes(const char *s, size_t len) {
106  resize_write_buffer(len);
107  memcpy(&write_buffer[cur_pos], s, len);
108  cur_pos += len;
109}
110
111static void write_32bit_value(uint32_t i) {
112  write_bytes((char*)&i, 4);
113}
114
115static void write_64bit_value(uint64_t i) {
116  write_bytes((char*)&i, 8);
117}
118
119static uint32_t length_of_string(const char *s) {
120  return (strlen(s) / 4) + 1;
121}
122
123static void write_string(const char *s) {
124  uint32_t len = length_of_string(s);
125  write_32bit_value(len);
126  write_bytes(s, strlen(s));
127  write_bytes("\0\0\0\0", 4 - (strlen(s) % 4));
128}
129
130static uint32_t read_32bit_value() {
131  uint32_t val;
132
133  if (new_file)
134    return (uint32_t)-1;
135
136  val = *(uint32_t*)&write_buffer[cur_pos];
137  cur_pos += 4;
138  return val;
139}
140
141static uint64_t read_64bit_value() {
142  uint64_t val;
143
144  if (new_file)
145    return (uint64_t)-1;
146
147  val = *(uint64_t*)&write_buffer[cur_pos];
148  cur_pos += 8;
149  return val;
150}
151
152static char *mangle_filename(const char *orig_filename) {
153  char *filename = 0;
154  int prefix_len = 0;
155  int prefix_strip = 0;
156  int level = 0;
157  const char *fname = orig_filename, *ptr = NULL;
158  const char *prefix = getenv("GCOV_PREFIX");
159  const char *prefix_strip_str = getenv("GCOV_PREFIX_STRIP");
160
161  if (!prefix)
162    return strdup(orig_filename);
163
164  if (prefix_strip_str) {
165    prefix_strip = atoi(prefix_strip_str);
166
167    /* Negative GCOV_PREFIX_STRIP values are ignored */
168    if (prefix_strip < 0)
169      prefix_strip = 0;
170  }
171
172  prefix_len = strlen(prefix);
173  filename = malloc(prefix_len + 1 + strlen(orig_filename) + 1);
174  strcpy(filename, prefix);
175
176  if (prefix[prefix_len - 1] != '/')
177    strcat(filename, "/");
178
179  for (ptr = fname + 1; *ptr != '\0' && level < prefix_strip; ++ptr) {
180    if (*ptr != '/') continue;
181    fname = ptr;
182    ++level;
183  }
184
185  strcat(filename, fname);
186
187  return filename;
188}
189
190static void recursive_mkdir(char *filename) {
191  int i;
192
193  for (i = 1; filename[i] != '\0'; ++i) {
194    if (filename[i] != '/') continue;
195    filename[i] = '\0';
196#ifdef _WIN32
197    _mkdir(filename);
198#else
199    mkdir(filename, 0755);  /* Some of these will fail, ignore it. */
200#endif
201    filename[i] = '/';
202  }
203}
204
205static int map_file() {
206  fseek(output_file, 0L, SEEK_END);
207  file_size = ftell(output_file);
208
209  /* A size of 0 is invalid to `mmap'. Return a fail here, but don't issue an
210   * error message because it should "just work" for the user. */
211  if (file_size == 0)
212    return -1;
213
214  write_buffer = mmap(0, file_size, PROT_READ | PROT_WRITE,
215                      MAP_FILE | MAP_SHARED, fd, 0);
216  if (write_buffer == (void *)-1) {
217    int errnum = errno;
218    fprintf(stderr, "profiling: %s: cannot map: %s\n", filename,
219            strerror(errnum));
220    return -1;
221  }
222  return 0;
223}
224
225static void unmap_file() {
226  if (msync(write_buffer, file_size, MS_SYNC) == -1) {
227    int errnum = errno;
228    fprintf(stderr, "profiling: %s: cannot msync: %s\n", filename,
229            strerror(errnum));
230  }
231
232  /* We explicitly ignore errors from unmapping because at this point the data
233   * is written and we don't care.
234   */
235  (void)munmap(write_buffer, file_size);
236  write_buffer = NULL;
237  file_size = 0;
238}
239
240/*
241 * --- LLVM line counter API ---
242 */
243
244/* A file in this case is a translation unit. Each .o file built with line
245 * profiling enabled will emit to a different file. Only one file may be
246 * started at a time.
247 */
248void llvm_gcda_start_file(const char *orig_filename, const char version[4]) {
249  const char *mode = "r+b";
250  filename = mangle_filename(orig_filename);
251
252  /* Try just opening the file. */
253  new_file = 0;
254  fd = open(filename, O_RDWR);
255
256  if (fd == -1) {
257    /* Try opening the file, creating it if necessary. */
258    new_file = 1;
259    mode = "w+b";
260    fd = open(filename, O_RDWR | O_CREAT, 0644);
261    if (fd == -1) {
262      /* Try creating the directories first then opening the file. */
263      recursive_mkdir(filename);
264      fd = open(filename, O_RDWR | O_CREAT, 0644);
265      if (fd == -1) {
266        /* Bah! It's hopeless. */
267        int errnum = errno;
268        fprintf(stderr, "profiling: %s: cannot open: %s\n", filename,
269                strerror(errnum));
270        return;
271      }
272    }
273  }
274
275  output_file = fdopen(fd, mode);
276
277  /* Initialize the write buffer. */
278  write_buffer = NULL;
279  cur_buffer_size = 0;
280  cur_pos = 0;
281
282  if (new_file) {
283    resize_write_buffer(WRITE_BUFFER_SIZE);
284    memset(write_buffer, 0, WRITE_BUFFER_SIZE);
285  } else {
286    if (map_file() == -1) {
287      /* mmap failed, try to recover by clobbering */
288      new_file = 1;
289      write_buffer = NULL;
290      cur_buffer_size = 0;
291      resize_write_buffer(WRITE_BUFFER_SIZE);
292      memset(write_buffer, 0, WRITE_BUFFER_SIZE);
293    }
294  }
295
296  /* gcda file, version, stamp LLVM. */
297  write_bytes("adcg", 4);
298  write_bytes(version, 4);
299  write_bytes("MVLL", 4);
300
301#ifdef DEBUG_GCDAPROFILING
302  fprintf(stderr, "llvmgcda: [%s]\n", orig_filename);
303#endif
304}
305
306/* Given an array of pointers to counters (counters), increment the n-th one,
307 * where we're also given a pointer to n (predecessor).
308 */
309void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
310                                          uint64_t **counters) {
311  uint64_t *counter;
312  uint32_t pred;
313
314  pred = *predecessor;
315  if (pred == 0xffffffff)
316    return;
317  counter = counters[pred];
318
319  /* Don't crash if the pred# is out of sync. This can happen due to threads,
320     or because of a TODO in GCOVProfiling.cpp buildEdgeLookupTable(). */
321  if (counter)
322    ++*counter;
323#ifdef DEBUG_GCDAPROFILING
324  else
325    fprintf(stderr,
326            "llvmgcda: increment_indirect_counter counters=%08llx, pred=%u\n",
327            *counter, *predecessor);
328#endif
329}
330
331void llvm_gcda_emit_function(uint32_t ident, const char *function_name,
332                             uint8_t use_extra_checksum) {
333  uint32_t len = 2;
334
335  if (use_extra_checksum)
336    len++;
337#ifdef DEBUG_GCDAPROFILING
338  fprintf(stderr, "llvmgcda: function id=0x%08x name=%s\n", ident,
339          function_name ? function_name : "NULL");
340#endif
341  if (!output_file) return;
342
343  /* function tag */
344  write_bytes("\0\0\0\1", 4);
345  if (function_name)
346    len += 1 + length_of_string(function_name);
347  write_32bit_value(len);
348  write_32bit_value(ident);
349  write_32bit_value(0);
350  if (use_extra_checksum)
351    write_32bit_value(0);
352  if (function_name)
353    write_string(function_name);
354}
355
356void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
357  uint32_t i;
358  uint64_t *old_ctrs = NULL;
359  uint32_t val = 0;
360  uint64_t save_cur_pos = cur_pos;
361
362  if (!output_file) return;
363
364  val = read_32bit_value();
365
366  if (val != (uint32_t)-1) {
367    /* There are counters present in the file. Merge them. */
368    if (val != 0x01a10000) {
369      fprintf(stderr, "profiling:invalid arc tag (0x%08x)\n", val);
370      return;
371    }
372
373    val = read_32bit_value();
374    if (val == (uint32_t)-1 || val / 2 != num_counters) {
375      fprintf(stderr, "profiling:invalid number of counters (%d)\n", val);
376      return;
377    }
378
379    old_ctrs = malloc(sizeof(uint64_t) * num_counters);
380    for (i = 0; i < num_counters; ++i)
381      old_ctrs[i] = read_64bit_value();
382  }
383
384  cur_pos = save_cur_pos;
385
386  /* Counter #1 (arcs) tag */
387  write_bytes("\0\0\xa1\1", 4);
388  write_32bit_value(num_counters * 2);
389  for (i = 0; i < num_counters; ++i) {
390    counters[i] += (old_ctrs ? old_ctrs[i] : 0);
391    write_64bit_value(counters[i]);
392  }
393
394  free(old_ctrs);
395
396#ifdef DEBUG_GCDAPROFILING
397  fprintf(stderr, "llvmgcda:   %u arcs\n", num_counters);
398  for (i = 0; i < num_counters; ++i)
399    fprintf(stderr, "llvmgcda:   %llu\n", (unsigned long long)counters[i]);
400#endif
401}
402
403void llvm_gcda_summary_info() {
404  const int obj_summary_len = 9; // length for gcov compatibility
405  uint32_t i;
406  uint32_t runs = 1;
407  uint32_t val = 0;
408  uint64_t save_cur_pos = cur_pos;
409
410  if (!output_file) return;
411
412  val = read_32bit_value();
413
414  if (val != (uint32_t)-1) {
415    /* There are counters present in the file. Merge them. */
416    if (val != 0xa1000000) {
417      fprintf(stderr, "profiling:invalid object tag (0x%08x)\n", val);
418      return;
419    }
420
421    val = read_32bit_value(); // length
422    if (val != obj_summary_len) {
423      fprintf(stderr, "profiling:invalid object length (%d)\n", val); // length
424      return;
425    }
426
427    read_32bit_value(); // checksum, unused
428    read_32bit_value(); // num, unused
429    runs += read_32bit_value(); // add previous run count to new counter
430  }
431
432  cur_pos = save_cur_pos;
433
434  /* Object summary tag */
435  write_bytes("\0\0\0\xa1", 4);
436  write_32bit_value(obj_summary_len);
437  write_32bit_value(0); // checksum, unused
438  write_32bit_value(0); // num, unused
439  write_32bit_value(runs);
440  for (i = 3; i < obj_summary_len; ++i)
441    write_32bit_value(0);
442
443  /* Program summary tag */
444  write_bytes("\0\0\0\xa3", 4); // tag indicates 1 program
445  write_32bit_value(0); // 0 length
446
447#ifdef DEBUG_GCDAPROFILING
448  fprintf(stderr, "llvmgcda:   %u runs\n", runs);
449#endif
450}
451
452void llvm_gcda_end_file() {
453  /* Write out EOF record. */
454  if (output_file) {
455    write_bytes("\0\0\0\0\0\0\0\0", 8);
456
457    if (new_file) {
458      fwrite(write_buffer, cur_pos, 1, output_file);
459      free(write_buffer);
460    } else {
461      unmap_file();
462    }
463
464    fclose(output_file);
465    output_file = NULL;
466    write_buffer = NULL;
467  }
468  free(filename);
469
470#ifdef DEBUG_GCDAPROFILING
471  fprintf(stderr, "llvmgcda: -----\n");
472#endif
473}
474
475void llvm_register_writeout_function(writeout_fn fn) {
476  struct writeout_fn_node *new_node = malloc(sizeof(struct writeout_fn_node));
477  new_node->fn = fn;
478  new_node->next = NULL;
479
480  if (!writeout_fn_head) {
481    writeout_fn_head = writeout_fn_tail = new_node;
482  } else {
483    writeout_fn_tail->next = new_node;
484    writeout_fn_tail = new_node;
485  }
486}
487
488void llvm_writeout_files() {
489  struct writeout_fn_node *curr = writeout_fn_head;
490
491  while (curr) {
492    curr->fn();
493    curr = curr->next;
494  }
495}
496
497void llvm_delete_writeout_function_list() {
498  while (writeout_fn_head) {
499    struct writeout_fn_node *node = writeout_fn_head;
500    writeout_fn_head = writeout_fn_head->next;
501    free(node);
502  }
503
504  writeout_fn_head = writeout_fn_tail = NULL;
505}
506
507void llvm_register_flush_function(flush_fn fn) {
508  struct flush_fn_node *new_node = malloc(sizeof(struct flush_fn_node));
509  new_node->fn = fn;
510  new_node->next = NULL;
511
512  if (!flush_fn_head) {
513    flush_fn_head = flush_fn_tail = new_node;
514  } else {
515    flush_fn_tail->next = new_node;
516    flush_fn_tail = new_node;
517  }
518}
519
520void __gcov_flush() {
521  struct flush_fn_node *curr = flush_fn_head;
522
523  while (curr) {
524    curr->fn();
525    curr = curr->next;
526  }
527}
528
529void llvm_delete_flush_function_list() {
530  while (flush_fn_head) {
531    struct flush_fn_node *node = flush_fn_head;
532    flush_fn_head = flush_fn_head->next;
533    free(node);
534  }
535
536  flush_fn_head = flush_fn_tail = NULL;
537}
538
539void llvm_gcov_init(writeout_fn wfn, flush_fn ffn) {
540  static int atexit_ran = 0;
541
542  if (wfn)
543    llvm_register_writeout_function(wfn);
544
545  if (ffn)
546    llvm_register_flush_function(ffn);
547
548  if (atexit_ran == 0) {
549    atexit_ran = 1;
550
551    /* Make sure we write out the data and delete the data structures. */
552    atexit(llvm_delete_flush_function_list);
553    atexit(llvm_delete_writeout_function_list);
554    atexit(llvm_writeout_files);
555  }
556}
557