runtime/libprofile/PathProfiling.c

   1 /*===-- PathProfiling.c - Support library for path profiling --------------===*\
   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 path profiling
  11 |* instrumentation pass.  This should be used with the -insert-path-profiling
  12 |* LLVM pass.
  13 |*
  14 \*===----------------------------------------------------------------------===*/
  15
  16 #include "Profiling.h"
  17 #include "llvm/Analysis/ProfileInfoTypes.h"
  18 #include "llvm/Support/DataTypes.h"
  19 #include <sys/types.h>
  20 #if !defined(_MSC_VER) && !defined(__MINGW32__)
  21 #include <unistd.h>
  22 #else
  23 #include <io.h>
  24 #endif
  25 #include <string.h>
  26 #include <stdlib.h>
  27 #include <stdio.h>
  28
  29 /* Must use __inline in Microsoft C */
  30 #if defined(_MSC_VER)
  31 #define inline __inline
  32 #endif
  33
  34 /* note that this is used for functions with large path counts,
  35          but it is unlikely those paths will ALL be executed */
  36 #define ARBITRARY_HASH_BIN_COUNT 100
  37
  38 typedef struct pathHashEntry_s {
  39   uint32_t pathNumber;
  40   uint32_t pathCount;
  41   struct pathHashEntry_s* next;
  42 } pathHashEntry_t;
  43
  44 typedef struct pathHashTable_s {
  45   pathHashEntry_t* hashBins[ARBITRARY_HASH_BIN_COUNT];
  46   uint32_t pathCounts;
  47 } pathHashTable_t;
  48
  49 typedef struct {
  50   enum ProfilingStorageType type;
  51   uint32_t size;
  52   void* array;
  53 } ftEntry_t;
  54
  55 /* pointer to the function table allocated in the instrumented program */
  56 ftEntry_t* ft;
  57 uint32_t ftSize;
  58
  59 /* write an array table to file */
  60 void writeArrayTable(uint32_t fNumber, ftEntry_t* ft, uint32_t* funcCount) {
  61   int outFile = getOutFile();
  62   uint32_t arrayHeaderLocation = 0;
  63   uint32_t arrayCurrentLocation = 0;
  64   uint32_t arrayIterator = 0;
  65   uint32_t functionUsed = 0;
  66   uint32_t pathCounts = 0;
  67
  68   /* look through each entry in the array to determine whether the function
  69      was executed at all */
  70   for( arrayIterator = 0; arrayIterator < ft->size; arrayIterator++ ) {
  71     uint32_t pc = ((uint32_t*)ft->array)[arrayIterator];
  72
  73     /* was this path executed? */
  74     if( pc ) {
  75       PathProfileTableEntry pte;
  76       pte.pathNumber = arrayIterator;
  77       pte.pathCounter = pc;
  78       pathCounts++;
  79
  80       /* one-time initialization stuff */
  81       if(!functionUsed) {
  82         arrayHeaderLocation = lseek(outFile, 0, SEEK_CUR);
  83         lseek(outFile, sizeof(PathProfileHeader), SEEK_CUR);
  84         functionUsed = 1;
  85         (*funcCount)++;
  86       }
  87
  88       /* write path data */
  89       if (write(outFile, &pte, sizeof(PathProfileTableEntry)) < 0) {
  90         fprintf(stderr, "error: unable to write path entry to output file.\n");
  91         return;
  92       }
  93     }
  94   }
  95
  96   /* If this function was executed, write the header */
  97   if( functionUsed ) {
  98     PathProfileHeader fHeader;
  99     fHeader.fnNumber = fNumber;
 100     fHeader.numEntries = pathCounts;
 101
 102     arrayCurrentLocation = lseek(outFile, 0, SEEK_CUR);
 103     lseek(outFile, arrayHeaderLocation, SEEK_SET);
 104
 105     if (write(outFile, &fHeader, sizeof(PathProfileHeader)) < 0) {
 106       fprintf(stderr,
 107               "error: unable to write function header to output file.\n");
 108       return;
 109     }
 110
 111     lseek(outFile, arrayCurrentLocation, SEEK_SET);
 112   }
 113 }
 114
 115 static inline uint32_t hash (uint32_t key) {
 116   /* this may benefit from a proper hash function */
 117   return key%ARBITRARY_HASH_BIN_COUNT;
 118 }
 119
 120 /* output a specific function's hash table to the profile file */
 121 void writeHashTable(uint32_t functionNumber, pathHashTable_t* hashTable) {
 122   int outFile = getOutFile();
 123   PathProfileHeader header;
 124   uint32_t i;
 125
 126   header.fnNumber = functionNumber;
 127   header.numEntries = hashTable->pathCounts;
 128
 129   if (write(outFile, &header, sizeof(PathProfileHeader)) < 0) {
 130     fprintf(stderr, "error: unable to write function header to output file.\n");
 131     return;
 132   }
 133
 134   for (i = 0; i < ARBITRARY_HASH_BIN_COUNT; i++) {
 135     pathHashEntry_t* hashEntry = hashTable->hashBins[i];
 136
 137     while (hashEntry) {
 138       pathHashEntry_t* temp;
 139
 140       PathProfileTableEntry pte;
 141       pte.pathNumber = hashEntry->pathNumber;
 142       pte.pathCounter = hashEntry->pathCount;
 143
 144       if (write(outFile, &pte, sizeof(PathProfileTableEntry)) < 0) {
 145         fprintf(stderr, "error: unable to write path entry to output file.\n");
 146         return;
 147       }
 148
 149       temp = hashEntry;
 150       hashEntry = hashEntry->next;
 151       free (temp);
 152
 153     }
 154   }
 155 }
 156
 157 /* Return a pointer to this path's specific path counter */
 158 static inline uint32_t* getPathCounter(uint32_t functionNumber,
 159                                        uint32_t pathNumber) {
 160   pathHashTable_t* hashTable;
 161   pathHashEntry_t* hashEntry;
 162   uint32_t index = hash(pathNumber);
 163
 164   if( ft[functionNumber-1].array == 0)
 165     ft[functionNumber-1].array = calloc(sizeof(pathHashTable_t), 1);
 166
 167   hashTable = (pathHashTable_t*)((ftEntry_t*)ft)[functionNumber-1].array;
 168   hashEntry = hashTable->hashBins[index];
 169
 170   while (hashEntry) {
 171     if (hashEntry->pathNumber == pathNumber) {
 172       return &hashEntry->pathCount;
 173     }
 174
 175     hashEntry = hashEntry->next;
 176   }
 177
 178   hashEntry = malloc(sizeof(pathHashEntry_t));
 179   hashEntry->pathNumber = pathNumber;
 180   hashEntry->pathCount = 0;
 181   hashEntry->next = hashTable->hashBins[index];
 182   hashTable->hashBins[index] = hashEntry;
 183   hashTable->pathCounts++;
 184   return &hashEntry->pathCount;
 185 }
 186
 187 /* Increment a specific path's count */
 188 void llvm_increment_path_count (uint32_t functionNumber, uint32_t pathNumber) {
 189   uint32_t* pathCounter = getPathCounter(functionNumber, pathNumber);
 190   if( *pathCounter < 0xffffffff )
 191     (*pathCounter)++;
 192 }
 193
 194 /* Increment a specific path's count */
 195 void llvm_decrement_path_count (uint32_t functionNumber, uint32_t pathNumber) {
 196   uint32_t* pathCounter = getPathCounter(functionNumber, pathNumber);
 197   (*pathCounter)--;
 198 }
 199
 200 /*
 201  * Writes out a path profile given a function table, in the following format.
 202  *
 203  *
 204  *      | <-- 32 bits --> |
 205  *      +-----------------+-----------------+
 206  * 0x00 | profileType     | functionCount   |
 207  *      +-----------------+-----------------+
 208  * 0x08 | functionNum     | profileEntries  |  // function 1
 209  *      +-----------------+-----------------+
 210  * 0x10 | pathNumber      | pathCounter     |  // entry 1.1
 211  *      +-----------------+-----------------+
 212  * 0x18 | pathNumber      | pathCounter     |  // entry 1.2
 213  *      +-----------------+-----------------+
 214  *  ... |       ...       |       ...       |  // entry 1.n
 215  *      +-----------------+-----------------+
 216  *  ... | functionNum     | profileEntries  |  // function 2
 217  *      +-----------------+-----------------+
 218  *  ... | pathNumber      | pathCounter     |  // entry 2.1
 219  *      +-----------------+-----------------+
 220  *  ... | pathNumber      | pathCounter     |  // entry 2.2
 221  *      +-----------------+-----------------+
 222  *  ... |       ...       |       ...       |  // entry 2.n
 223  *      +-----------------+-----------------+
 224  *
 225  */
 226 static void pathProfAtExitHandler(void) {
 227   int outFile = getOutFile();
 228   uint32_t i;
 229   uint32_t header[2] = { PathInfo, 0 };
 230   uint32_t headerLocation;
 231   uint32_t currentLocation;
 232
 233   /* skip over the header for now */
 234   headerLocation = lseek(outFile, 0, SEEK_CUR);
 235   lseek(outFile, 2*sizeof(uint32_t), SEEK_CUR);
 236
 237   /* Iterate through each function */
 238   for( i = 0; i < ftSize; i++ ) {
 239     if( ft[i].type == ProfilingArray ) {
 240       writeArrayTable(i+1,&ft[i],header + 1);
 241
 242     } else if( ft[i].type == ProfilingHash ) {
 243       /* If the hash exists, write it to file */
 244       if( ft[i].array ) {
 245         writeHashTable(i+1,ft[i].array);
 246         header[1]++;
 247         free(ft[i].array);
 248       }
 249     }
 250   }
 251
 252   /* Setup and write the path profile header */
 253   currentLocation = lseek(outFile, 0, SEEK_CUR);
 254   lseek(outFile, headerLocation, SEEK_SET);
 255
 256   if (write(outFile, header, sizeof(header)) < 0) {
 257     fprintf(stderr,
 258             "error: unable to write path profile header to output file.\n");
 259     return;
 260   }
 261
 262   lseek(outFile, currentLocation, SEEK_SET);
 263 }
 264 /* llvm_start_path_profiling - This is the main entry point of the path
 265  * profiling library.  It is responsible for setting up the atexit handler.
 266  */
 267 int llvm_start_path_profiling(int argc, const char** argv,
 268                               void* functionTable, uint32_t numElements) {
 269   int Ret = save_arguments(argc, argv);
 270   ft = functionTable;
 271   ftSize = numElements;
 272   atexit(pathProfAtExitHandler);
 273
 274   return Ret;
 275 }