fpcmp.cpp revision ff2c64c979a404faab95f2cc3288fc31f88157cc 
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
20using namespace llvm;
21
22namespace {
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.
37static 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
45static 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
56static 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
66static void CompareNumbers(char *&F1P, char *&F2P, char *F1End, char *F2End) {
67  char *F1NumEnd, *F2NumEnd;
68  double V1, V2;
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
108int main(int argc, char **argv) {
109  cl::ParseCommandLineOptions(argc, argv);
110
111  // mmap in the files.
112  unsigned File1Len, File2Len;
113  char *File1Start, *File2Start;
114  OpenFile(File1, File1Len, File1Start);
115  OpenFile(File2, File2Len, File2Start);
116
117  // Okay, now that we opened the files, scan them for the first difference.
118  char *File1End = File1Start+File1Len;
119  char *File2End = File2Start+File2Len;
120  char *F1P = File1Start;
121  char *F2P = File2Start;
122
123  while (1) {
124    // Scan for the end of file or first difference.
125    while (F1P < File1End && F2P < File2End && *F1P == *F2P)
126      ++F1P, ++F2P;
127
128    if (F1P >= File1End || F2P >= File2End) break;
129
130    // Okay, we must have found a difference.  Backup to the start of the
131    // current number each stream is at so that we can compare from the
132    // beginning.
133    F1P = BackupNumber(F1P, File1Start);
134    F2P = BackupNumber(F2P, File2Start);
135
136    // Now that we are at the start of the numbers, compare them, exiting if
137    // they don't match.
138    CompareNumbers(F1P, F2P, File1End, File2End);
139  }
140
141  // Okay, we reached the end of file.  If both files are at the end, we
142  // succeeded.
143  if (F1P >= File1End && F2P >= File2End) return 0;
144
145  // Otherwise, we might have run off the end due to a number, backup and retry.
146  F1P = BackupNumber(F1P, File1Start);
147  F2P = BackupNumber(F2P, File2Start);
148
149  // Now that we are at the start of the numbers, compare them, exiting if
150  // they don't match.
151  CompareNumbers(F1P, F2P, File1End, File2End);
152
153  // If we found the end, we succeeded.
154  if (F1P >= File1End && F2P >= File2End) return 0;
155
156  return 1;
157}
158
159