runtime/libprofile/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 "llvm/Support/DataTypes.h"
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <sys/stat.h>
  28 #include <sys/types.h>
  29 #ifdef _MSC_VER
  30 #include <direct.h>
  31 #endif
  32
  33 /* #define DEBUG_GCDAPROFILING */
  34
  35 /*
  36  * --- GCOV file format I/O primitives ---
  37  */
  38
  39 static FILE *output_file = NULL;
  40
  41 static void write_int32(uint32_t i) {
  42   fwrite(&i, 4, 1, output_file);
  43 }
  44
  45 static void write_int64(uint64_t i) {
  46   uint32_t lo, hi;
  47   lo = i >>  0;
  48   hi = i >> 32;
  49
  50   write_int32(lo);
  51   write_int32(hi);
  52 }
  53
  54 static uint32_t length_of_string(const char *s) {
  55   return (strlen(s) / 4) + 1;
  56 }
  57
  58 static void write_string(const char *s) {
  59   uint32_t len = length_of_string(s);
  60   write_int32(len);
  61   fwrite(s, strlen(s), 1, output_file);
  62   fwrite("\0\0\0\0", 4 - (strlen(s) % 4), 1, output_file);
  63 }
  64
  65 static char *mangle_filename(const char *orig_filename) {
  66   /* TODO: handle GCOV_PREFIX_STRIP */
  67   const char *prefix;
  68   char *filename = 0;
  69
  70   prefix = getenv("GCOV_PREFIX");
  71
  72   if (!prefix)
  73     return strdup(orig_filename);
  74
  75   filename = malloc(strlen(prefix) + 1 + strlen(orig_filename) + 1);
  76   strcpy(filename, prefix);
  77   strcat(filename, "/");
  78   strcat(filename, orig_filename);
  79
  80   return filename;
  81 }
  82
  83 static void recursive_mkdir(const char *filename) {
  84   char *pathname;
  85   int i, e;
  86
  87   for (i = 1, e = strlen(filename); i != e; ++i) {
  88     if (filename[i] == '/') {
  89       pathname = malloc(i + 1);
  90       strncpy(pathname, filename, i);
  91       pathname[i] = '\0';
  92 #ifdef _WIN32
  93       _mkdir(pathname);
  94 #else
  95       mkdir(pathname, 0750);  /* some of these will fail, ignore it. */
  96 #endif
  97       free(pathname);
  98     }
  99   }
 100 }
 101
 102 /*
 103  * --- LLVM line counter API ---
 104  */
 105
 106 /* A file in this case is a translation unit. Each .o file built with line
 107  * profiling enabled will emit to a different file. Only one file may be
 108  * started at a time.
 109  */
 110 void llvm_gcda_start_file(const char *orig_filename) {
 111   char *filename;
 112   filename = mangle_filename(orig_filename);
 113   recursive_mkdir(filename);
 114   output_file = fopen(filename, "wb");
 115
 116   /* gcda file, version 404*, stamp LLVM. */
 117   fwrite("adcg*404MVLL", 12, 1, output_file);
 118
 119 #ifdef DEBUG_GCDAPROFILING
 120   printf("llvmgcda: [%s]\n", orig_filename);
 121 #endif
 122
 123   free(filename);
 124 }
 125
 126 /* Given an array of pointers to counters (counters), increment the n-th one,
 127  * where we're also given a pointer to n (predecessor).
 128  */
 129 void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
 130                                           uint64_t **counters) {
 131   uint64_t *counter;
 132   uint32_t pred;
 133
 134   pred = *predecessor;
 135   if (pred == 0xffffffff)
 136     return;
 137   counter = counters[pred];
 138
 139   /* Don't crash if the pred# is out of sync. This can happen due to threads,
 140      or because of a TODO in GCOVProfiling.cpp buildEdgeLookupTable(). */
 141   if (counter)
 142     ++*counter;
 143 #ifdef DEBUG_GCDAPROFILING
 144   else
 145     printf("llvmgcda: increment_indirect_counter counters=%x, pred=%u\n",
 146            state_table_row, *predecessor);
 147 #endif
 148 }
 149
 150 void llvm_gcda_emit_function(uint32_t ident, const char *function_name) {
 151 #ifdef DEBUG_GCDAPROFILING
 152   printf("llvmgcda: function id=%x\n", ident);
 153 #endif
 154
 155   /* function tag */
 156   fwrite("\0\0\0\1", 4, 1, output_file);
 157   write_int32(3 + 1 + length_of_string(function_name));
 158   write_int32(ident);
 159   write_int32(0);
 160   write_int32(0);
 161   write_string(function_name);
 162 }
 163
 164 void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
 165   uint32_t i;
 166   /* counter #1 (arcs) tag */
 167   fwrite("\0\0\xa1\1", 4, 1, output_file);
 168   write_int32(num_counters * 2);
 169   for (i = 0; i < num_counters; ++i) {
 170     write_int64(counters[i]);
 171   }
 172
 173 #ifdef DEBUG_GCDAPROFILING
 174   printf("llvmgcda:   %u arcs\n", num_counters);
 175   for (i = 0; i < num_counters; ++i) {
 176     printf("llvmgcda:   %llu\n", (unsigned long long)counters[i]);
 177   }
 178 #endif
 179 }
 180
 181 void llvm_gcda_end_file() {
 182   /* Write out EOF record. */
 183   fwrite("\0\0\0\0\0\0\0\0", 8, 1, output_file);
 184   fclose(output_file);
 185   output_file = NULL;
 186
 187 #ifdef DEBUG_GCDAPROFILING
 188   printf("llvmgcda: -----\n");
 189 #endif
 190 }