utils/fpcmp/fpcmp.cpp

   1 //===- fpcmp.cpp - A fuzzy "cmp" that permits floating point noise --------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and is distributed under
   6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // fpcmp is a tool that basically works like the 'cmp' tool, except that it can
  11 // tolerate errors due to floating point noise, with the -r option.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "Support/CommandLine.h"
  16 #include "Support/FileUtilities.h"
  17 #include <iostream>
  18 #include <cmath>
  19
  20 using namespace llvm;
  21
  22 namespace {
  23   cl::opt<std::string>
  24   File1(cl::Positional, cl::desc("<input file #1>"), cl::Required);
  25   cl::opt<std::string>
  26   File2(cl::Positional, cl::desc("<input file #2>"), cl::Required);
  27
  28   cl::opt<double>
  29   RelTolerance("r", cl::desc("Relative error tolerated"), cl::init(0));
  30   cl::opt<double>
  31   AbsTolerance("a", cl::desc("Absolute error tolerated"), cl::init(0));
  32 }
  33
  34
  35 /// OpenFile - mmap the specified file into the address space for reading, and
  36 /// return the length and address of the buffer.
  37 static void OpenFile(const std::string &Filename, unsigned &Len, char* &BufPtr){
  38   BufPtr = (char*)ReadFileIntoAddressSpace(Filename, Len);
  39   if (BufPtr == 0) {
  40     std::cerr << "Error: cannot open file '" << Filename << "'\n";
  41     exit(2);
  42   }
  43 }
  44
  45 static bool isNumberChar(char C) {
  46   switch (C) {
  47   case '0': case '1': case '2': case '3': case '4':
  48   case '5': case '6': case '7': case '8': case '9':
  49   case '.': case '+': case '-':
  50   case 'e':
  51   case 'E': return true;
  52   default: return false;
  53   }
  54 }
  55
  56 static char *BackupNumber(char *Pos, char *FirstChar) {
  57   // If we didn't stop in the middle of a number, don't backup.
  58   if (!isNumberChar(*Pos)) return Pos;
  59
  60   // Otherwise, return to the start of the number.
  61   while (Pos > FirstChar && isNumberChar(Pos[-1]))
  62     --Pos;
  63   return Pos;
  64 }
  65
  66 static void CompareNumbers(char *&F1P, char *&F2P, char *F1End, char *F2End) {
  67   char *F1NumEnd, *F2NumEnd;
  68   double V1 = 0.0, V2 = 0.0;
  69   // If we stop on numbers, compare their difference.
  70   if (isNumberChar(*F1P) && isNumberChar(*F2P)) {
  71     V1 = strtod(F1P, &F1NumEnd);
  72     V2 = strtod(F2P, &F2NumEnd);
  73   } else {
  74     // Otherwise, the diff failed.
  75     F1NumEnd = F1P;
  76     F2NumEnd = F2P;
  77   }
  78
  79   if (F1NumEnd == F1P || F2NumEnd == F2P) {
  80     std::cerr << "Comparison failed, not a numeric difference.\n";
  81     exit(1);
  82   }
  83
  84   // Check to see if these are inside the absolute tolerance
  85   if (AbsTolerance < std::abs(V1-V2)) {
  86     // Nope, check the relative tolerance...
  87     double Diff;
  88     if (V2)
  89       Diff = std::abs(V1/V2 - 1.0);
  90     else if (V1)
  91       Diff = std::abs(V2/V1 - 1.0);
  92     else
  93       Diff = 0;  // Both zero.
  94     if (Diff > RelTolerance) {
  95       std::cerr << "Compared: " << V1 << " and " << V2 << ": diff = "
  96                 << Diff << "\n";
  97       std::cerr << "Out of tolerance: rel/abs: " << RelTolerance
  98                 << "/" << AbsTolerance << "\n";
  99       exit(1);
 100     }
 101   }
 102
 103   // Otherwise, advance our read pointers to the end of the numbers.
 104   F1P = F1NumEnd;  F2P = F2NumEnd;
 105 }
 106
 107 // PadFileIfNeeded - If the files are not identical, we will have to be doing
 108 // numeric comparisons in here.  There are bad cases involved where we (i.e.,
 109 // strtod) might run off the beginning or end of the file if it starts or ends
 110 // with a number.  Because of this, if needed, we pad the file so that it starts
 111 // and ends with a null character.
 112 static void PadFileIfNeeded(char *&FileStart, char *&FileEnd, char *&FP) {
 113   if (isNumberChar(FileStart[0]) || isNumberChar(FileEnd[-1])) {
 114     unsigned FileLen = FileEnd-FileStart;
 115     char *NewFile = new char[FileLen+2];
 116     NewFile[0] = 0;              // Add null padding
 117     NewFile[FileLen+1] = 0;      // Add null padding
 118     memcpy(NewFile+1, FileStart, FileLen);
 119     FP = NewFile+(FP-FileStart)+1;
 120     FileStart = NewFile+1;
 121     FileEnd = FileStart+FileLen;
 122   }
 123 }
 124
 125 int main(int argc, char **argv) {
 126   cl::ParseCommandLineOptions(argc, argv);
 127
 128   // mmap in the files.
 129   unsigned File1Len, File2Len;
 130   char *File1Start, *File2Start;
 131   OpenFile(File1, File1Len, File1Start);
 132   OpenFile(File2, File2Len, File2Start);
 133
 134   // Okay, now that we opened the files, scan them for the first difference.
 135   char *File1End = File1Start+File1Len;
 136   char *File2End = File2Start+File2Len;
 137   char *F1P = File1Start;
 138   char *F2P = File2Start;
 139
 140   // Scan for the end of file or first difference.
 141   while (F1P < File1End && F2P < File2End && *F1P == *F2P)
 142     ++F1P, ++F2P;
 143
 144   // Common case: identifical files.
 145   if (F1P == File1End && F2P == File2End) return 0;
 146
 147   // If the files need padding, do so now.
 148   PadFileIfNeeded(File1Start, File1End, F1P);
 149   PadFileIfNeeded(File2Start, File2End, F2P);
 150
 151   while (1) {
 152     // Scan for the end of file or next difference.
 153     while (F1P < File1End && F2P < File2End && *F1P == *F2P)
 154       ++F1P, ++F2P;
 155
 156     if (F1P >= File1End || F2P >= File2End) break;
 157
 158     // Okay, we must have found a difference.  Backup to the start of the
 159     // current number each stream is at so that we can compare from the
 160     // beginning.
 161     F1P = BackupNumber(F1P, File1Start);
 162     F2P = BackupNumber(F2P, File2Start);
 163
 164     // Now that we are at the start of the numbers, compare them, exiting if
 165     // they don't match.
 166     CompareNumbers(F1P, F2P, File1End, File2End);
 167   }
 168
 169   // Okay, we reached the end of file.  If both files are at the end, we
 170   // succeeded.
 171   bool F1AtEnd = F1P >= File1End;
 172   bool F2AtEnd = F2P >= File2End;
 173   if (F1AtEnd & F2AtEnd) return 0;
 174
 175   // Otherwise, we might have run off the end due to a number: backup and retry.
 176   if (F1AtEnd && isNumberChar(F1P[-1])) --F1P;
 177   if (F2AtEnd && isNumberChar(F2P[-1])) --F2P;
 178   F1P = BackupNumber(F1P, File1Start);
 179   F2P = BackupNumber(F2P, File2Start);
 180
 181   // Now that we are at the start of the numbers, compare them, exiting if
 182   // they don't match.
 183   CompareNumbers(F1P, F2P, File1End, File2End);
 184
 185   // If we found the end, we succeeded.
 186   if (F1P >= File1End && F2P >= File2End) return 0;
 187
 188   return 1;
 189 }
 190