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