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
  28 /* #define DEBUG_GCDAPROFILING */
  29
  30 /*
  31  * --- GCOV file format I/O primitives ---
  32  */
  33
  34 static FILE *output_file = NULL;
  35
  36 static void write_int32(uint32_t i) {
  37   fwrite(&i, 4, 1, output_file);
  38 }
  39
  40 static void write_int64(uint64_t i) {
  41   uint32_t lo, hi;
  42   lo = i >>  0;
  43   hi = i >> 32;
  44
  45   write_int32(lo);
  46   write_int32(hi);
  47 }
  48
  49 /*
  50  * --- LLVM line counter API ---
  51  */
  52
  53 /* A file in this case is a translation unit. Each .o file built with line
  54  * profiling enabled will emit to a different file. Only one file may be
  55  * started at a time.
  56  */
  57 void llvm_gcda_start_file(const char *filename) {
  58   output_file = fopen(filename, "w+");
  59
  60   /* gcda file, version 404*, stamp LLVM. */
  61   fwrite("adcg*404MVLL", 12, 1, output_file);
  62
  63 #ifdef DEBUG_GCDAPROFILING
  64   printf("llvmgcda: [%s]\n", filename);
  65 #endif
  66 }
  67
  68 /* Given an array of pointers to counters (counters), increment the n-th one,
  69  * where we're also given a pointer to n (predecessor).
  70  */
  71 void llvm_gcda_increment_indirect_counter(uint32_t *predecessor,
  72                                           uint64_t **counters) {
  73   uint64_t *counter;
  74   if (*predecessor == 0xffffffff)
  75     return;
  76
  77   /* Don't crash if the pred# is out of sync. This can happen due to threads,
  78      or because of a TODO in GCOVProfiling.cpp buildEdgeLookupTable(). */
  79   if ((counter = counters[*predecessor]))
  80     ++*counter;
  81 #ifdef DEBUG_GCDAPROFILING
  82   else
  83     printf("llvmgcda: increment_indirect_counter counters=%x, pred=%u\n",
  84            state_table_row, *predecessor);
  85 #endif
  86 }
  87
  88 void llvm_gcda_emit_function(uint32_t ident) {
  89 #ifdef DEBUG_GCDAPROFILING
  90   printf("llvmgcda: function id=%x\n", ident);
  91 #endif
  92
  93   /* function tag */
  94   fwrite("\0\0\0\1", 4, 1, output_file);
  95   write_int32(2);
  96   write_int32(ident);
  97   write_int32(0);
  98 }
  99
 100 void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
 101   uint32_t i;
 102   /* counter #1 (arcs) tag */
 103   fwrite("\0\0\xa1\1", 4, 1, output_file);
 104   write_int32(num_counters * 2);
 105   for (i = 0; i < num_counters; ++i) {
 106     write_int64(counters[i]);
 107   }
 108
 109 #ifdef DEBUG_GCDAPROFILING
 110   printf("llvmgcda:   %u arcs\n", num_counters);
 111   for (i = 0; i < num_counters; ++i) {
 112     printf("llvmgcda:   %llu\n", (unsigned long long)counters[i]);
 113   }
 114 #endif
 115 }
 116
 117 void llvm_gcda_end_file() {
 118   /* Write out EOF record. */
 119   fwrite("\0\0\0\0\0\0\0\0", 8, 1, output_file);
 120   fclose(output_file);
 121   output_file = NULL;
 122
 123 #ifdef DEBUG_GCDAPROFILING
 124   printf("llvmgcda: -----\n");
 125 #endif
 126 }