fpcmp.cpp revision 9a459abed2ecd06b5b5d2f517b27cd9bf1919690 
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 "Config/fcntl.h"
18#include "Config/sys/mman.h"
19#include <iostream>
20#include <cmath>
21
22using namespace llvm;
23
24namespace {
25  cl::opt<std::string>
26  File1(cl::Positional, cl::desc("<input file #1>"), cl::Required);
27  cl::opt<std::string>
28  File2(cl::Positional, cl::desc("<input file #2>"), cl::Required);
29
30  cl::opt<double>
31  RelTolerance("r", cl::desc("Relative error tolerated"), cl::init(0));
32  cl::opt<double>
33  AbsTolerance("a", cl::desc("Absolute error tolerated"), cl::init(0));
34}
35
36
37/// OpenFile - mmap the specified file into the address space for reading, and
38/// return the length and address of the buffer.
39static void OpenFile(const std::string &Filename, unsigned &Len, char* &BufPtr){
40  int FD = open(Filename.c_str(), O_RDONLY);
41  if (FD == -1 || (Len = getFileSize(Filename)) == ~0U) {
42    std::cerr << "Error: cannot open file '" << Filename << "'\n";
43    exit(2);
44  }
45
46  // mmap in the file all at once...
47  BufPtr = (char*)mmap(0, Len, PROT_READ, MAP_PRIVATE, FD, 0);
48
49  if (BufPtr == (char*)MAP_FAILED) {
50    std::cerr << "Error: cannot open file '" << Filename << "'\n";
51    exit(2);
52  }
53}
54
55static bool isNumberChar(char C) {
56  switch (C) {
57  case '0': case '1': case '2': case '3': case '4':
58  case '5': case '6': case '7': case '8': case '9':
59  case '.': case '+': case '-':
60  case 'e':
61  case 'E': return true;
62  default: return false;
63  }
64}
65
66static char *BackupNumber(char *Pos, char *FirstChar) {
67  while (Pos > FirstChar && isNumberChar(Pos[-1]))
68    --Pos;
69  return Pos;
70}
71
72static void CompareNumbers(char *&F1P, char *&F2P, char *F1End, char *F2End) {
73  char *F1NumEnd, *F2NumEnd;
74  double V1 = strtod(F1P, &F1NumEnd);
75  double V2 = strtod(F2P, &F2NumEnd);
76
77  if (F1NumEnd == F1P || F2NumEnd == F2P) {
78    std::cerr << "Comparison failed, not a numeric difference.\n";
79    exit(1);
80  }
81
82  // Check to see if these are inside the absolute tolerance
83  if (AbsTolerance < std::abs(V1-V2)) {
84    // Nope, check the relative tolerance...
85    double Diff;
86    if (V2)
87      Diff = std::abs(V1/V2 - 1.0);
88    else if (V1)
89      Diff = std::abs(V2/V1 - 1.0);
90    else
91      Diff = 0;  // Both zero.
92    if (Diff > RelTolerance) {
93      std::cerr << "Compared: " << V1 << " and " << V2 << ": diff = "
94                << Diff << "\n";
95      std::cerr << "Out of tolerance: rel/abs: " << RelTolerance
96                << "/" << AbsTolerance << "\n";
97      exit(1);
98    }
99  }
100
101  // Otherwise, advance our read pointers to the end of the numbers.
102  F1P = F1NumEnd;  F2P = F2NumEnd;
103}
104
105
106int main(int argc, char **argv) {
107  cl::ParseCommandLineOptions(argc, argv);
108
109  // mmap in the files.
110  unsigned File1Len, File2Len;
111  char *File1Start, *File2Start;
112  OpenFile(File1, File1Len, File1Start);
113  OpenFile(File2, File2Len, File2Start);
114
115  // Okay, now that we opened the files, scan them for the first difference.
116  char *File1End = File1Start+File1Len;
117  char *File2End = File2Start+File2Len;
118  char *F1P = File1Start;
119  char *F2P = File2Start;
120
121  while (1) {
122    // Scan for the end of file or first difference.
123    while (F1P < File1End && F2P < File2End && *F1P == *F2P)
124      ++F1P, ++F2P;
125
126    if (F1P >= File1End || F2P >= File2End) break;
127
128    // Okay, we must have found a difference.  Backup to the start of the
129    // current number each stream is at so that we can compare from the
130    // beginning.
131    F1P = BackupNumber(F1P, File1Start);
132    F2P = BackupNumber(F2P, File2Start);
133
134    // Now that we are at the start of the numbers, compare them, exiting if
135    // they don't match.
136    CompareNumbers(F1P, F2P, File1End, File2End);
137  }
138
139  // Okay, we reached the end of file.  If both files are at the end, we
140  // succeeded.
141  if (F1P >= File1End && F2P >= File2End) return 0;
142
143  // Otherwise, we might have run off the end due to a number, backup and retry.
144  F1P = BackupNumber(F1P, File1Start);
145  F2P = BackupNumber(F2P, File2Start);
146
147  // Now that we are at the start of the numbers, compare them, exiting if
148  // they don't match.
149  CompareNumbers(F1P, F2P, File1End, File2End);
150
151  // If we found the end, we succeeded.
152  if (F1P >= File1End && F2P >= File2End) return 0;
153
154  return 1;
155}
156
157