GCDAProfiling.c revision 468eb10c6051c6f93df75cfc34fc98180dea1bbf 
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 <fcntl.h>
24#include <stdio.h>
25#include <stdlib.h>
26#include <string.h>
27#include <sys/stat.h>
28#include <sys/mman.h>
29#include <sys/types.h>
30#ifdef _WIN32
31#include <direct.h>
32#endif
33
34#ifndef _MSC_VER
35#include <stdint.h>
36#else
37typedef unsigned int uint32_t;
38typedef unsigned int uint64_t;
39#endif
40
41/* #define DEBUG_GCDAPROFILING */
42
43/*
44 * --- GCOV file format I/O primitives ---
45 */
46
47/*
48 * The current file we're outputting.
49 */
50static FILE *output_file = NULL;
51
52/*
53 * Buffer that we write things into.
54 */
55#define NEW_WRITE_BUFFER_SIZE (128 * 1024)
56static char *new_write_buffer = NULL;
57static uint64_t cur_buffer_size = 0;
58static uint64_t cur_pos = 0;
59static uint64_t file_size = 0;
60static int new_file = 0;
61static int fd = -1;
62
63/*
64 * A list of functions to write out the data.
65 */
66typedef void (*writeout_fn)();
67
68struct writeout_fn_node {
69  writeout_fn fn;
70  struct writeout_fn_node *next;
71};
72
73static struct writeout_fn_node *writeout_fn_head = NULL;
74static struct writeout_fn_node *writeout_fn_tail = NULL;
75
76/*
77 *  A list of flush functions that our __gcov_flush() function should call.
78 */
79typedef void (*flush_fn)();
80
81struct flush_fn_node {
82  flush_fn fn;
83  struct flush_fn_node *next;
84};
85
86static struct flush_fn_node *flush_fn_head = NULL;
87static struct flush_fn_node *flush_fn_tail = NULL;
88
89static void resize_write_buffer(uint64_t size) {
90  if (!new_file) return;
91  size += cur_pos;
92  if (size <= cur_buffer_size) return;
93  size = (size - 1) / NEW_WRITE_BUFFER_SIZE + 1;
94  size *= NEW_WRITE_BUFFER_SIZE;
95  new_write_buffer = realloc(new_write_buffer, size);
96  cur_buffer_size = size;
97}
98
99static void write_bytes(const char *s, size_t len) {
100  resize_write_buffer(len);
101  memcpy(&new_write_buffer[cur_pos], s, len);
102  cur_pos += len;
103}
104
105static void write_32bit_value(uint32_t i) {
106  write_bytes((char*)&i, 4);
107}
108
109static void write_64bit_value(uint64_t i) {
110  write_bytes((char*)&i, 8);
111}
112
113static uint32_t length_of_string(const char *s) {
114  return (strlen(s) / 4) + 1;
115}
116
117static void write_string(const char *s) {
118  uint32_t len = length_of_string(s);
119  write_32bit_value(len);
120  write_bytes(s, strlen(s));
121  write_bytes("\0\0\0\0", 4 - (strlen(s) % 4));
122}
123
124static uint32_t read_32bit_value() {
125  uint32_t val;
126
127  if (new_file)
128    return (uint32_t)-1;
129
130  val = *(uint32_t*)&new_write_buffer[cur_pos];
131  cur_pos += 4;
132  return val;
133}
134
135static uint64_t read_64bit_value() {
136  uint64_t val;
137
138  if (new_file)
139    return (uint64_t)-1;
140
141  val = *(uint64_t*)&new_write_buffer[cur_pos];
142  cur_pos += 8;
143  return val;
144}
145
146static char *mangle_filename(const char *orig_filename) {
147  char *filename = 0;
148  int prefix_len = 0;
149  int prefix_strip = 0;
150  int level = 0;
151  const char *fname = orig_filename, *ptr = NULL;
152  const char *prefix = getenv("GCOV_PREFIX");
153  const char *prefix_strip_str = getenv("GCOV_PREFIX_STRIP");
154
155  if (!prefix)
156    return strdup(orig_filename);
157
158  if (prefix_strip_str) {
159    prefix_strip = atoi(prefix_strip_str);
160
161    /* Negative GCOV_PREFIX_STRIP values are ignored */
162    if (prefix_strip < 0)
163      prefix_strip = 0;
164  }
165
166  prefix_len = strlen(prefix);
167  filename = malloc(prefix_len + 1 + strlen(orig_filename) + 1);
168  strcpy(filename, prefix);
169
170  if (prefix[prefix_len - 1] != '/')
171    strcat(filename, "/");
172
173  for (ptr = fname + 1; *ptr != '\0' && level < prefix_strip; ++ptr) {
174    if (*ptr != '/') continue;
175    fname = ptr;
176    ++level;
177  }
178
179  strcat(filename, fname);
180
181  return filename;
182}
183
184static void recursive_mkdir(char *filename) {
185  int i;
186
187  for (i = 1; filename[i] != '\0'; ++i) {
188    if (filename[i] != '/') continue;
189    filename[i] = '\0';
190#ifdef _WIN32
191    _mkdir(filename);
192#else
193    mkdir(filename, 0755);  /* Some of these will fail, ignore it. */
194#endif
195    filename[i] = '/';
196  }
197}
198
199static void map_file() {
200  fseek(output_file, 0L, SEEK_END);
201  file_size = ftell(output_file);
202
203  new_write_buffer = mmap(0, file_size, PROT_READ | PROT_WRITE,
204                          MAP_FILE | MAP_SHARED, fd, 0);
205}
206
207static void unmap_file() {
208  msync(new_write_buffer, file_size, MS_SYNC);
209  munmap(new_write_buffer, file_size);
210  new_write_buffer = NULL;
211  file_size = 0;
212}
213
214/*
215 * --- LLVM line counter API ---
216 */
217
218/* A file in this case is a translation unit. Each .o file built with line
219 * profiling enabled will emit to a different file. Only one file may be
220 * started at a time.
221 */
222void llvm_gcda_start_file(const char *orig_filename, const char version[4]) {
223  char *filename = mangle_filename(orig_filename);
224  const char *mode = "r+b";
225
226  /* Try just opening the file. */
227  new_file = 0;
228  fd = open(filename, O_RDWR);
229
230  if (fd == -1) {
231    /* Try opening the file, creating it if necessary. */
232    int mode = 0644;
233    new_file = 1;
234    mode = "w+b";
235    fd = open(filename, O_RDWR | O_CREAT, mode);
236    if (fd == -1) {
237      /* Try creating the directories first then opening the file. */
238      recursive_mkdir(filename);
239      fd = open(filename, O_RDWR | O_CREAT, mode);
240      if (!output_file) {
241        /* Bah! It's hopeless. */
242        fprintf(stderr, "profiling:%s: cannot open\n", filename);
243        free(filename);
244        return;
245      }
246    }
247  }
248
249  output_file = fdopen(fd, mode);
250
251  /* Initialize the write buffer. */
252  new_write_buffer = NULL;
253  cur_buffer_size = 0;
254  cur_pos = 0;
255
256  if (new_file) {
257    resize_write_buffer(NEW_WRITE_BUFFER_SIZE);
258    memset(new_write_buffer, 0, NEW_WRITE_BUFFER_SIZE);
259  } else {
260    map_file();
261  }
262
263  /* gcda file, version, stamp LLVM. */
264  write_bytes("adcg", 4);
265  write_bytes(version, 4);
266  write_bytes("MVLL", 4);
267
268  free(filename);
269
270#ifdef DEBUG_GCDAPROFILING
271  fprintf(stderr, "llvmgcda: [%s]\n", orig_filename);
272#endif
273}
274
275/* Given an array of pointers to counters (counters), increment the n-th one,
276 * where we're also given a pointer to n (predecessor).
277 */
278void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
279                                          uint64_t **counters) {
280  uint64_t *counter;
281  uint32_t pred;
282
283  pred = *predecessor;
284  if (pred == 0xffffffff)
285    return;
286  counter = counters[pred];
287
288  /* Don't crash if the pred# is out of sync. This can happen due to threads,
289     or because of a TODO in GCOVProfiling.cpp buildEdgeLookupTable(). */
290  if (counter)
291    ++*counter;
292#ifdef DEBUG_GCDAPROFILING
293  else
294    fprintf(stderr,
295            "llvmgcda: increment_indirect_counter counters=%08llx, pred=%u\n",
296            *counter, *predecessor);
297#endif
298}
299
300void llvm_gcda_emit_function(uint32_t ident, const char *function_name,
301                             uint8_t use_extra_checksum) {
302  uint32_t len = 2;
303
304  if (use_extra_checksum)
305    len++;
306#ifdef DEBUG_GCDAPROFILING
307  fprintf(stderr, "llvmgcda: function id=0x%08x name=%s\n", ident,
308          function_name ? function_name : "NULL");
309#endif
310  if (!output_file) return;
311
312  /* function tag */
313  write_bytes("\0\0\0\1", 4);
314  if (function_name)
315    len += 1 + length_of_string(function_name);
316  write_32bit_value(len);
317  write_32bit_value(ident);
318  write_32bit_value(0);
319  if (use_extra_checksum)
320    write_32bit_value(0);
321  if (function_name)
322    write_string(function_name);
323}
324
325void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
326  uint32_t i;
327  uint64_t *old_ctrs = NULL;
328  uint32_t val = 0;
329  uint64_t save_cur_pos = cur_pos;
330
331  if (!output_file) return;
332
333  val = read_32bit_value();
334
335  if (val != (uint32_t)-1) {
336    /* There are counters present in the file. Merge them. */
337    if (val != 0x01a10000) {
338      fprintf(stderr, "profiling:invalid magic number (0x%08x)\n", val);
339      return;
340    }
341
342    val = read_32bit_value();
343    if (val == (uint32_t)-1 || val / 2 != num_counters) {
344      fprintf(stderr, "profiling:invalid number of counters (%d)\n", val);
345      return;
346    }
347
348    old_ctrs = malloc(sizeof(uint64_t) * num_counters);
349    for (i = 0; i < num_counters; ++i)
350      old_ctrs[i] = read_64bit_value();
351  }
352
353  cur_pos = save_cur_pos;
354
355  /* Counter #1 (arcs) tag */
356  write_bytes("\0\0\xa1\1", 4);
357  write_32bit_value(num_counters * 2);
358  for (i = 0; i < num_counters; ++i) {
359    counters[i] += (old_ctrs ? old_ctrs[i] : 0);
360    write_64bit_value(counters[i]);
361  }
362
363  free(old_ctrs);
364
365#ifdef DEBUG_GCDAPROFILING
366  fprintf(stderr, "llvmgcda:   %u arcs\n", num_counters);
367  for (i = 0; i < num_counters; ++i)
368    fprintf(stderr, "llvmgcda:   %llu\n", (unsigned long long)counters[i]);
369#endif
370}
371
372void llvm_gcda_end_file() {
373  /* Write out EOF record. */
374  if (!output_file) return;
375  write_bytes("\0\0\0\0\0\0\0\0", 8);
376
377  if (new_file) {
378    fwrite(new_write_buffer, cur_pos, 1, output_file);
379    free(new_write_buffer);
380  } else {
381    unmap_file();
382  }
383
384  fclose(output_file);
385  output_file = NULL;
386  new_write_buffer = NULL;
387
388#ifdef DEBUG_GCDAPROFILING
389  fprintf(stderr, "llvmgcda: -----\n");
390#endif
391}
392
393void llvm_register_writeout_function(writeout_fn fn) {
394  struct writeout_fn_node *new_node = malloc(sizeof(struct writeout_fn_node));
395  new_node->fn = fn;
396  new_node->next = NULL;
397
398  if (!writeout_fn_head) {
399    writeout_fn_head = writeout_fn_tail = new_node;
400  } else {
401    writeout_fn_tail->next = new_node;
402    writeout_fn_tail = new_node;
403  }
404}
405
406void llvm_writeout_files() {
407  struct writeout_fn_node *curr = writeout_fn_head;
408
409  while (curr) {
410    curr->fn();
411    curr = curr->next;
412  }
413}
414
415void llvm_delete_writeout_function_list() {
416  while (writeout_fn_head) {
417    struct writeout_fn_node *node = writeout_fn_head;
418    writeout_fn_head = writeout_fn_head->next;
419    free(node);
420  }
421
422  writeout_fn_head = writeout_fn_tail = NULL;
423}
424
425void llvm_register_flush_function(flush_fn fn) {
426  struct flush_fn_node *new_node = malloc(sizeof(struct flush_fn_node));
427  new_node->fn = fn;
428  new_node->next = NULL;
429
430  if (!flush_fn_head) {
431    flush_fn_head = flush_fn_tail = new_node;
432  } else {
433    flush_fn_tail->next = new_node;
434    flush_fn_tail = new_node;
435  }
436}
437
438void __gcov_flush() {
439  struct flush_fn_node *curr = flush_fn_head;
440
441  while (curr) {
442    curr->fn();
443    curr = curr->next;
444  }
445}
446
447void llvm_delete_flush_function_list() {
448  while (flush_fn_head) {
449    struct flush_fn_node *node = flush_fn_head;
450    flush_fn_head = flush_fn_head->next;
451    free(node);
452  }
453
454  flush_fn_head = flush_fn_tail = NULL;
455}
456
457void llvm_gcov_init(writeout_fn wfn, flush_fn ffn) {
458  static int atexit_ran = 0;
459
460  if (wfn)
461    llvm_register_writeout_function(wfn);
462
463  if (ffn)
464    llvm_register_flush_function(ffn);
465
466  if (atexit_ran == 0) {
467    atexit_ran = 1;
468
469    /* Make sure we write out the data and delete the data structures. */
470    atexit(llvm_delete_flush_function_list);
471    atexit(llvm_delete_writeout_function_list);
472    atexit(llvm_writeout_files);
473  }
474}
475