GCDAProfiling.c revision 346e348af5740db3660c84490d2c1bbba7c570e5 
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 <stdio.h>
24#include <stdlib.h>
25#include <string.h>
26#include <sys/stat.h>
27#include <sys/types.h>
28#ifdef _WIN32
29#include <direct.h>
30#endif
31
32#ifndef _MSC_VER
33#include <stdint.h>
34#else
35typedef unsigned int uint32_t;
36typedef unsigned int uint64_t;
37#endif
38
39/* #define DEBUG_GCDAPROFILING */
40
41/*
42 * --- GCOV file format I/O primitives ---
43 */
44
45/*
46 * The current file we're outputting.
47 */
48static FILE *output_file = NULL;
49
50/*
51 * A list of functions to write out the data.
52 */
53typedef void (*writeout_fn)();
54
55struct writeout_fn_node {
56  writeout_fn fn;
57  struct writeout_fn_node *next;
58};
59
60struct writeout_fn_node *writeout_fn_head = NULL;
61struct writeout_fn_node *writeout_fn_tail = NULL;
62
63/*
64 *  A list of flush functions that our __gcov_flush() function should call.
65 */
66typedef void (*flush_fn)();
67
68struct flush_fn_node {
69  flush_fn fn;
70  struct flush_fn_node *next;
71};
72
73struct flush_fn_node *flush_fn_head = NULL;
74struct flush_fn_node *flush_fn_tail = NULL;
75
76static void write_int32(uint32_t i) {
77  fwrite(&i, 4, 1, output_file);
78}
79
80static uint64_t write_from_buffer(uint64_t *buffer, size_t size) {
81  if (fwrite(buffer, 8, size, output_file) != size)
82    return (uint64_t)-1;
83
84  return 0;
85}
86
87static uint32_t length_of_string(const char *s) {
88  return (strlen(s) / 4) + 1;
89}
90
91static void write_string(const char *s) {
92  uint32_t len = length_of_string(s);
93  write_int32(len);
94  fwrite(s, strlen(s), 1, output_file);
95  fwrite("\0\0\0\0", 4 - (strlen(s) % 4), 1, output_file);
96}
97
98static uint32_t read_int32() {
99  uint32_t tmp;
100
101  if (fread(&tmp, 1, 4, output_file) != 4)
102    return (uint32_t)-1;
103
104  return tmp;
105}
106
107static uint64_t read_into_buffer(uint64_t *buffer, size_t size) {
108  if (fread(buffer, 8, size, output_file) != size)
109    return (uint64_t)-1;
110
111  return 0;
112}
113
114static char *mangle_filename(const char *orig_filename) {
115  char *filename = 0;
116  int prefix_len = 0;
117  int prefix_strip = 0;
118  int level = 0;
119  const char *fname = orig_filename, *ptr = NULL;
120  const char *prefix = getenv("GCOV_PREFIX");
121  const char *tmp = getenv("GCOV_PREFIX_STRIP");
122
123  if (!prefix)
124    return strdup(orig_filename);
125
126  if (tmp) {
127    prefix_strip = atoi(tmp);
128
129    /* Negative GCOV_PREFIX_STRIP values are ignored */
130    if (prefix_strip < 0)
131      prefix_strip = 0;
132  }
133
134  prefix_len = strlen(prefix);
135  filename = malloc(prefix_len + 1 + strlen(orig_filename) + 1);
136  strcpy(filename, prefix);
137
138  if (prefix[prefix_len - 1] != '/')
139    strcat(filename, "/");
140
141  for (ptr = fname + 1; *ptr != '\0' && level < prefix_strip; ++ptr) {
142    if (*ptr != '/') continue;
143    fname = ptr;
144    ++level;
145  }
146
147  strcat(filename, fname);
148
149  return filename;
150}
151
152static void recursive_mkdir(char *filename) {
153  int i;
154
155  for (i = 1; filename[i] != '\0'; ++i) {
156    if (filename[i] != '/') continue;
157    filename[i] = '\0';
158#ifdef _WIN32
159    _mkdir(filename);
160#else
161    mkdir(filename, 0755);  /* Some of these will fail, ignore it. */
162#endif
163    filename[i] = '/';
164  }
165}
166
167/*
168 * --- LLVM line counter API ---
169 */
170
171/* A file in this case is a translation unit. Each .o file built with line
172 * profiling enabled will emit to a different file. Only one file may be
173 * started at a time.
174 */
175void llvm_gcda_start_file(const char *orig_filename, const char version[4]) {
176  char *filename = mangle_filename(orig_filename);
177
178  /* Try just opening the file. */
179  output_file = fopen(filename, "r+b");
180
181  if (!output_file) {
182    /* Try opening the file, creating it if necessary. */
183    output_file = fopen(filename, "w+b");
184    if (!output_file) {
185      /* Try creating the directories first then opening the file. */
186      recursive_mkdir(filename);
187      output_file = fopen(filename, "w+b");
188      if (!output_file) {
189        /* Bah! It's hopeless. */
190        fprintf(stderr, "profiling:%s: cannot open\n", filename);
191        free(filename);
192        return;
193      }
194    }
195  }
196
197  /* gcda file, version, stamp LLVM. */
198  fwrite("adcg", 4, 1, output_file);
199  fwrite(version, 4, 1, output_file);
200  fwrite("MVLL", 4, 1, output_file);
201  free(filename);
202
203#ifdef DEBUG_GCDAPROFILING
204  fprintf(stderr, "llvmgcda: [%s]\n", orig_filename);
205#endif
206}
207
208/* Given an array of pointers to counters (counters), increment the n-th one,
209 * where we're also given a pointer to n (predecessor).
210 */
211void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
212                                          uint64_t **counters) {
213  uint64_t *counter;
214  uint32_t pred;
215
216  pred = *predecessor;
217  if (pred == 0xffffffff)
218    return;
219  counter = counters[pred];
220
221  /* Don't crash if the pred# is out of sync. This can happen due to threads,
222     or because of a TODO in GCOVProfiling.cpp buildEdgeLookupTable(). */
223  if (counter)
224    ++*counter;
225#ifdef DEBUG_GCDAPROFILING
226  else
227    fprintf(stderr,
228            "llvmgcda: increment_indirect_counter counters=%08llx, pred=%u\n",
229            *counter, *predecessor);
230#endif
231}
232
233void llvm_gcda_emit_function(uint32_t ident, const char *function_name,
234                             uint8_t use_extra_checksum) {
235  uint32_t len = 2;
236  if (use_extra_checksum)
237    len++;
238#ifdef DEBUG_GCDAPROFILING
239  fprintf(stderr, "llvmgcda: function id=0x%08x name=%s\n", ident,
240          function_name ? function_name : "NULL");
241#endif
242  if (!output_file) return;
243
244  /* function tag */
245  fwrite("\0\0\0\1", 4, 1, output_file);
246  if (function_name)
247    len += 1 + length_of_string(function_name);
248  write_int32(len);
249  write_int32(ident);
250  write_int32(0);
251  if (use_extra_checksum)
252    write_int32(0);
253  if (function_name)
254    write_string(function_name);
255}
256
257void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
258  uint32_t i;
259  uint64_t *old_ctrs = NULL;
260  uint32_t val = 0;
261  long pos = 0;
262
263  if (!output_file) return;
264
265  pos = ftell(output_file);
266  val = read_int32();
267
268  if (val != (uint32_t)-1) {
269    /* There are counters present in the file. Merge them. */
270    if (val != 0x01a10000) {
271      fprintf(stderr, "profiling:invalid magic number (0x%08x)\n", val);
272      return;
273    }
274
275    val = read_int32();
276    if (val == (uint32_t)-1 || val / 2 != num_counters) {
277      fprintf(stderr, "profiling:invalid number of counters (%d)\n", val);
278      return;
279    }
280
281    old_ctrs = malloc(sizeof(uint64_t) * num_counters);
282
283    if (read_into_buffer(old_ctrs, num_counters) == (uint64_t)-1) {
284      fprintf(stderr, "profiling:invalid number of counters (%d)\n",
285              num_counters);
286      return;
287    }
288  }
289
290  /* Reset for writing. */
291  fseek(output_file, pos, SEEK_SET);
292
293  /* Counter #1 (arcs) tag */
294  fwrite("\0\0\xa1\1", 4, 1, output_file);
295  write_int32(num_counters * 2);
296  for (i = 0; i < num_counters; ++i)
297    counters[i] += (old_ctrs ? old_ctrs[i] : 0);
298
299  if (write_from_buffer(counters, num_counters) == (uint64_t)-1) {
300    fprintf(stderr, "profiling:cannot write to output file\n");
301    return;
302  }
303
304  free(old_ctrs);
305
306#ifdef DEBUG_GCDAPROFILING
307  fprintf(stderr, "llvmgcda:   %u arcs\n", num_counters);
308  for (i = 0; i < num_counters; ++i)
309    fprintf(stderr, "llvmgcda:   %llu\n", (unsigned long long)counters[i]);
310#endif
311}
312
313void llvm_gcda_end_file() {
314  /* Write out EOF record. */
315  if (!output_file) return;
316  fwrite("\0\0\0\0\0\0\0\0", 8, 1, output_file);
317  fclose(output_file);
318  output_file = NULL;
319
320#ifdef DEBUG_GCDAPROFILING
321  fprintf(stderr, "llvmgcda: -----\n");
322#endif
323}
324
325void llvm_register_writeout_function(writeout_fn fn) {
326  struct writeout_fn_node *new_node = malloc(sizeof(struct writeout_fn_node));
327  new_node->fn = fn;
328  new_node->next = NULL;
329
330  if (!writeout_fn_head) {
331    writeout_fn_head = writeout_fn_tail = new_node;
332  } else {
333    writeout_fn_tail->next = new_node;
334    writeout_fn_tail = new_node;
335  }
336}
337
338void llvm_writeout_files() {
339  struct writeout_fn_node *curr = writeout_fn_head;
340
341  while (curr) {
342    curr->fn();
343    curr = curr->next;
344  }
345}
346
347void llvm_delete_writeout_function_list() {
348  while (writeout_fn_head) {
349    struct writeout_fn_node *node = writeout_fn_head;
350    writeout_fn_head = writeout_fn_head->next;
351    free(node);
352  }
353
354  writeout_fn_head = writeout_fn_tail = NULL;
355}
356
357void llvm_register_flush_function(flush_fn fn) {
358  struct flush_fn_node *new_node = malloc(sizeof(struct flush_fn_node));
359  new_node->fn = fn;
360  new_node->next = NULL;
361
362  if (!flush_fn_head) {
363    flush_fn_head = flush_fn_tail = new_node;
364  } else {
365    flush_fn_tail->next = new_node;
366    flush_fn_tail = new_node;
367  }
368}
369
370void __gcov_flush() {
371  struct flush_fn_node *curr = flush_fn_head;
372
373  while (curr) {
374    curr->fn();
375    curr = curr->next;
376  }
377}
378
379void llvm_delete_flush_function_list() {
380  while (flush_fn_head) {
381    struct flush_fn_node *node = flush_fn_head;
382    flush_fn_head = flush_fn_head->next;
383    free(node);
384  }
385
386  flush_fn_head = flush_fn_tail = NULL;
387}
388
389void llvm_gcov_init(writeout_fn wfn, flush_fn ffn) {
390  static int atexit_ran = 0;
391
392  if (wfn)
393    llvm_register_writeout_function(wfn);
394
395  if (ffn)
396    llvm_register_flush_function(ffn);
397
398  if (atexit_ran == 0) {
399    atexit_ran = 1;
400
401    /* Make sure we write out the data and delete the data structures. */
402    atexit(llvm_delete_flush_function_list);
403    atexit(llvm_delete_writeout_function_list);
404    atexit(llvm_writeout_files);
405  }
406}
407