src/compiler-rt/lib/profile/GCDAProfiling.c

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