GCDAProfiling.c revision 5a240c5c1746d07351fc38deb81c1794e8668d15 
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
45static FILE *output_file = NULL;
46
47static void write_int32(uint32_t i) {
48  fwrite(&i, 4, 1, output_file);
49}
50
51static 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
58static uint32_t length_of_string(const char *s) {
59  return (strlen(s) / 4) + 1;
60}
61
62static 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
69static char *mangle_filename(const char *orig_filename) {
70  /* TODO: handle GCOV_PREFIX_STRIP */
71  const char *prefix;
72  char *filename = 0;
73
74  prefix = getenv("GCOV_PREFIX");
75
76  if (!prefix)
77    return strdup(orig_filename);
78
79  filename = malloc(strlen(prefix) + 1 + strlen(orig_filename) + 1);
80  strcpy(filename, prefix);
81  strcat(filename, "/");
82  strcat(filename, orig_filename);
83
84  return filename;
85}
86
87static void recursive_mkdir(const char *filename) {
88  char *pathname;
89  int i, e;
90
91  for (i = 1, e = strlen(filename); i != e; ++i) {
92    if (filename[i] != '/') continue;
93    pathname = malloc(i + 1);
94    strncpy(pathname, filename, i);
95    pathname[i] = '\0';
96#ifdef _WIN32
97    _mkdir(pathname);
98#else
99    mkdir(pathname, 0750);  /* some of these will fail, ignore it. */
100#endif
101    free(pathname);
102  }
103}
104
105/*
106 * --- LLVM line counter API ---
107 */
108
109/* A file in this case is a translation unit. Each .o file built with line
110 * profiling enabled will emit to a different file. Only one file may be
111 * started at a time.
112 */
113void llvm_gcda_start_file(const char *orig_filename) {
114  char *filename;
115  filename = mangle_filename(orig_filename);
116  recursive_mkdir(filename);
117  output_file = fopen(filename, "w+b");
118
119  if (!output_file) {
120    const char *cptr = strrchr(orig_filename, '/');
121    output_file = fopen(cptr ? cptr + 1 : orig_filename, "w+b");
122
123    if (!output_file) {
124      fprintf(stderr, "profiling:%s: cannot open\n",
125              cptr ? cptr + 1 : orig_filename);
126      return;
127    }
128  }
129
130  /* gcda file, version 404*, stamp LLVM. */
131#ifdef __APPLE__
132  fwrite("adcg*204MVLL", 12, 1, output_file);
133#else
134  fwrite("adcg*404MVLL", 12, 1, output_file);
135#endif
136
137#ifdef DEBUG_GCDAPROFILING
138  printf("llvmgcda: [%s]\n", orig_filename);
139#endif
140
141  free(filename);
142}
143
144/* Given an array of pointers to counters (counters), increment the n-th one,
145 * where we're also given a pointer to n (predecessor).
146 */
147void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
148                                          uint64_t **counters) {
149  uint64_t *counter;
150  uint32_t pred;
151
152  pred = *predecessor;
153  if (pred == 0xffffffff)
154    return;
155  counter = counters[pred];
156
157  /* Don't crash if the pred# is out of sync. This can happen due to threads,
158     or because of a TODO in GCOVProfiling.cpp buildEdgeLookupTable(). */
159  if (counter)
160    ++*counter;
161#ifdef DEBUG_GCDAPROFILING
162  else
163    printf("llvmgcda: increment_indirect_counter counters=%x, pred=%u\n",
164           state_table_row, *predecessor);
165#endif
166}
167
168void llvm_gcda_emit_function(uint32_t ident, const char *function_name) {
169#ifdef DEBUG_GCDAPROFILING
170  printf("llvmgcda: function id=%x\n", ident);
171#endif
172  if (!output_file) return;
173
174  /* function tag */
175  fwrite("\0\0\0\1", 4, 1, output_file);
176  write_int32(3 + 1 + length_of_string(function_name));
177  write_int32(ident);
178  write_int32(0);
179  write_int32(0);
180  write_string(function_name);
181}
182
183void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
184  uint32_t i;
185
186  /* Counter #1 (arcs) tag */
187  if (!output_file) return;
188  fwrite("\0\0\xa1\1", 4, 1, output_file);
189  write_int32(num_counters * 2);
190  for (i = 0; i < num_counters; ++i)
191    write_int64(counters[i]);
192
193#ifdef DEBUG_GCDAPROFILING
194  printf("llvmgcda:   %u arcs\n", num_counters);
195  for (i = 0; i < num_counters; ++i)
196    printf("llvmgcda:   %llu\n", (unsigned long long)counters[i]);
197#endif
198}
199
200void llvm_gcda_end_file() {
201  /* Write out EOF record. */
202  if (!output_file) return;
203  fwrite("\0\0\0\0\0\0\0\0", 8, 1, output_file);
204  fclose(output_file);
205  output_file = NULL;
206
207#ifdef DEBUG_GCDAPROFILING
208  printf("llvmgcda: -----\n");
209#endif
210}
211