nsz Git - libfirm/blob - support/libfirmprof/instrument.c

   1 /**
   2  * Helper code to output instrumentation results.
   3  * This file is a supplement to libFirm. It is public domain.
   4  *  @author Matthias Braun, Steven Schaefer
   5  */
   6 #include <stdio.h>
   7 #include <string.h>
   8 #include <stdlib.h>
   9
  10 /* Prevent the compiler from mangling the name of this function. */
  11 void __init_firmprof(const char*, unsigned int*, size_t)
  12      asm("__init_firmprof");
  13
  14 typedef struct _profile_counter_t {
  15         const char *filename;
  16         unsigned   *counters;
  17         unsigned    len;
  18         struct _profile_counter_t *next;
  19 } profile_counter_t;
  20
  21 static profile_counter_t *counters = NULL;
  22
  23 /**
  24  * Write counter values to profiling output file.
  25  * We define our output format to be a sequence of 32-bit unsigned integer
  26  * values stored in little endian format.
  27  */
  28 void write_little_endian(unsigned *counter, unsigned len, FILE *f)
  29 {
  30         unsigned i;
  31
  32         for (i = 0; i < len; ++i) {
  33                 unsigned      v = counter[i];
  34                 unsigned char bytes[4];
  35
  36                 bytes[0] = ((v >>  0) & 0xff);
  37                 bytes[1] = ((v >>  8) & 0xff);
  38                 bytes[2] = ((v >> 16) & 0xff);
  39                 bytes[3] = ((v >> 24) & 0xff);
  40
  41                 fwrite(bytes, 1, 4, f);
  42         }
  43 }
  44
  45 static void write_profiles(void)
  46 {
  47         profile_counter_t *counter = counters;
  48         while (counter != NULL) {
  49                 profile_counter_t *next = counter->next;
  50                 FILE *f = fopen(counter->filename, "wb");
  51                 if (f == NULL) {
  52                         perror("Warning: couldn't open file for writing profiling data");
  53                 } else {
  54                         fputs("firmprof", f);
  55                         write_little_endian(counter->counters, counter->len, f);
  56                         fclose(f);
  57                 }
  58                 free(counter);
  59                 counter = next;
  60         }
  61 }
  62
  63 /**
  64  * Register a new profile counter. This is called by separate constructors
  65  * for each translation unit. Incidentally, referring to this function as
  66  * "__init_firmprof" is perfectly linker friendly.
  67  */
  68 void __init_firmprof(const char *filename,
  69                       unsigned int *counts, size_t len)
  70 {
  71         static int initialized = 0;
  72         profile_counter_t *counter;
  73
  74         if (!initialized) {
  75                 initialized = 1;
  76                 atexit(write_profiles);
  77         }
  78
  79         counter = (profile_counter_t*) malloc(sizeof(*counter));
  80         if (counter == NULL)
  81                 return;
  82
  83         counter->filename = filename;
  84         counter->counters = counts;
  85         counter->next     = counters;
  86         counter->len      = len;
  87
  88         counters = counter;
  89 }