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 <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
  35 typedef unsigned int uint32_t;
  36 typedef unsigned int uint64_t;
  37 #endif
  38
  39 /* #define DEBUG_GCDAPROFILING */
  40
  41 /*
  42  * --- GCOV file format I/O primitives ---
  43  */
  44
  45 static FILE *output_file = NULL;
  46
  47 static void write_int32(uint32_t i) {
  48   fwrite(&i, 4, 1, output_file);
  49 }
  50
  51 static void write_int64(uint64_t i) {
  52   uint32_t lo = i >>  0;
  53   uint32_t hi = i >> 32;
  54   write_int32(lo);
  55   write_int32(hi);
  56 }
  57
  58 static uint32_t length_of_string(const char *s) {
  59   return (strlen(s) / 4) + 1;
  60 }
  61
  62 static void write_string(const char *s) {
  63   uint32_t len = length_of_string(s);
  64   write_int32(len);
  65   fwrite(s, strlen(s), 1, output_file);
  66   fwrite("\0\0\0\0", 4 - (strlen(s) % 4), 1, output_file);
  67 }
  68
  69 static uint32_t read_int32() {
  70   uint32_t tmp;
  71
  72   if (fread(&tmp, 1, 4, output_file) != 4)
  73     return (uint32_t)-1;
  74
  75   return tmp;
  76 }
  77
  78 static uint64_t read_int64() {
  79   uint64_t tmp;
  80
  81   if (fread(&tmp, 1, 8, output_file) != 8)
  82     return (uint64_t)-1;
  83
  84   return tmp;
  85 }
  86
  87 static char *mangle_filename(const char *orig_filename) {
  88   char *filename = 0;
  89   int prefix_len = 0;
  90   int prefix_strip = 0;
  91   int level = 0;
  92   const char *fname = orig_filename, *ptr = NULL;
  93   const char *prefix = getenv("GCOV_PREFIX");
  94   const char *tmp = getenv("GCOV_PREFIX_STRIP");
  95
  96   if (!prefix)
  97     return strdup(orig_filename);
  98
  99   if (tmp) {
 100     prefix_strip = atoi(tmp);
 101
 102     /* Negative GCOV_PREFIX_STRIP values are ignored */
 103     if (prefix_strip < 0)
 104       prefix_strip = 0;
 105   }
 106
 107   prefix_len = strlen(prefix);
 108   filename = malloc(prefix_len + 1 + strlen(orig_filename) + 1);
 109   strcpy(filename, prefix);
 110
 111   if (prefix[prefix_len - 1] != '/')
 112     strcat(filename, "/");
 113
 114   for (ptr = fname + 1; *ptr != '\0' && level < prefix_strip; ++ptr) {
 115     if (*ptr != '/') continue;
 116     fname = ptr;
 117     ++level;
 118   }
 119
 120   strcat(filename, fname);
 121
 122   return filename;
 123 }
 124
 125 static void recursive_mkdir(char *filename) {
 126   int i;
 127
 128   for (i = 1; filename[i] != '\0'; ++i) {
 129     if (filename[i] != '/') continue;
 130     filename[i] = '\0';
 131 #ifdef _WIN32
 132     _mkdir(filename);
 133 #else
 134     mkdir(filename, 0755);  /* Some of these will fail, ignore it. */
 135 #endif
 136     filename[i] = '/';
 137   }
 138 }
 139
 140 /*
 141  * --- LLVM line counter API ---
 142  */
 143
 144 /* A file in this case is a translation unit. Each .o file built with line
 145  * profiling enabled will emit to a different file. Only one file may be
 146  * started at a time.
 147  */
 148 void llvm_gcda_start_file(const char *orig_filename) {
 149   char *filename = mangle_filename(orig_filename);
 150
 151   /* Try just opening the file. */
 152   output_file = fopen(filename, "r+b");
 153
 154   if (!output_file) {
 155     /* Try opening the file, creating it if necessary. */
 156     output_file = fopen(filename, "w+b");
 157     if (!output_file) {
 158       /* Try creating the directories first then opening the file. */
 159       recursive_mkdir(filename);
 160       output_file = fopen(filename, "w+b");
 161       if (!output_file) {
 162         /* Bah! It's hopeless. */
 163         fprintf(stderr, "profiling:%s: cannot open\n", filename);
 164         free(filename);
 165         return;
 166       }
 167     }
 168   }
 169
 170   /* gcda file, version 404*, stamp LLVM. */
 171 #ifdef __APPLE__
 172   fwrite("adcg*204MVLL", 12, 1, output_file);
 173 #else
 174   fwrite("adcg*404MVLL", 12, 1, output_file);
 175 #endif
 176
 177   free(filename);
 178
 179 #ifdef DEBUG_GCDAPROFILING
 180   fprintf(stderr, "llvmgcda: [%s]\n", orig_filename);
 181 #endif
 182 }
 183
 184 /* Given an array of pointers to counters (counters), increment the n-th one,
 185  * where we're also given a pointer to n (predecessor).
 186  */
 187 void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
 188                                           uint64_t **counters) {
 189   uint64_t *counter;
 190   uint32_t pred;
 191
 192   pred = *predecessor;
 193   if (pred == 0xffffffff)
 194     return;
 195   counter = counters[pred];
 196
 197   /* Don't crash if the pred# is out of sync. This can happen due to threads,
 198      or because of a TODO in GCOVProfiling.cpp buildEdgeLookupTable(). */
 199   if (counter)
 200     ++*counter;
 201 #ifdef DEBUG_GCDAPROFILING
 202   else
 203     fprintf(stderr,
 204             "llvmgcda: increment_indirect_counter counters=%08llx, pred=%u\n",
 205             *counter, *predecessor);
 206 #endif
 207 }
 208
 209 void llvm_gcda_emit_function(uint32_t ident, const char *function_name) {
 210 #ifdef DEBUG_GCDAPROFILING
 211   fprintf(stderr, "llvmgcda: function id=0x%08x\n", ident);
 212 #endif
 213   if (!output_file) return;
 214
 215   /* function tag */
 216   fwrite("\0\0\0\1", 4, 1, output_file);
 217   write_int32(3 + 1 + length_of_string(function_name));
 218   write_int32(ident);
 219   write_int32(0);
 220   write_int32(0);
 221   write_string(function_name);
 222 }
 223
 224 void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
 225   uint32_t i;
 226   uint64_t *old_ctrs = NULL;
 227   uint32_t val = 0;
 228   long pos = 0;
 229
 230   if (!output_file) return;
 231
 232   pos = ftell(output_file);
 233   val = read_int32();
 234
 235   if (val != (uint32_t)-1) {
 236     /* There are counters present in the file. Merge them. */
 237     uint32_t j;
 238
 239     if (val != 0x01a10000) {
 240       fprintf(stderr, "profiling: invalid magic number (0x%08x)\n", val);
 241       return;
 242     }
 243
 244     val = read_int32();
 245     if (val == (uint32_t)-1 || val / 2 != num_counters) {
 246       fprintf(stderr, "profiling: invalid number of counters (%d)\n", val);
 247       return;
 248     }
 249
 250     old_ctrs = malloc(sizeof(uint64_t) * num_counters);
 251
 252     for (j = 0; j < num_counters; ++j)
 253       old_ctrs[j] = read_int64();
 254   }
 255
 256   /* Reset for writing. */
 257   fseek(output_file, pos, SEEK_SET);
 258
 259   /* Counter #1 (arcs) tag */
 260   fwrite("\0\0\xa1\1", 4, 1, output_file);
 261   write_int32(num_counters * 2);
 262   for (i = 0; i < num_counters; ++i)
 263     write_int64(counters[i] + (old_ctrs ? old_ctrs[i] : 0));
 264
 265   free(old_ctrs);
 266
 267 #ifdef DEBUG_GCDAPROFILING
 268   fprintf(stderr, "llvmgcda:   %u arcs\n", num_counters);
 269   for (i = 0; i < num_counters; ++i)
 270     fprintf(stderr, "llvmgcda:   %llu\n", (unsigned long long)counters[i]);
 271 #endif
 272 }
 273
 274 void llvm_gcda_end_file() {
 275   /* Write out EOF record. */
 276   if (!output_file) return;
 277   fwrite("\0\0\0\0\0\0\0\0", 8, 1, output_file);
 278   fclose(output_file);
 279   output_file = NULL;
 280
 281 #ifdef DEBUG_GCDAPROFILING
 282   fprintf(stderr, "llvmgcda: -----\n");
 283 #endif
 284 }