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