FileUtilities.cpp revision 36b56886974eae4f9c5ebc96befd3e7bfe5de338 
1//===- Support/FileUtilities.cpp - File System Utilities ------------------===//
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 a family of utility functions which are useful for doing
11// various things with files.
12//
13//===----------------------------------------------------------------------===//
14
15#include "llvm/Support/FileUtilities.h"
16#include "llvm/ADT/SmallString.h"
17#include "llvm/Support/MemoryBuffer.h"
18#include "llvm/Support/Path.h"
19#include "llvm/Support/raw_ostream.h"
20#include "llvm/Support/system_error.h"
21#include <cctype>
22#include <cstdlib>
23#include <cstring>
24using namespace llvm;
25
26static bool isSignedChar(char C) {
27  return (C == '+' || C == '-');
28}
29
30static bool isExponentChar(char C) {
31  switch (C) {
32  case 'D':  // Strange exponential notation.
33  case 'd':  // Strange exponential notation.
34  case 'e':
35  case 'E': return true;
36  default: return false;
37  }
38}
39
40static bool isNumberChar(char C) {
41  switch (C) {
42  case '0': case '1': case '2': case '3': case '4':
43  case '5': case '6': case '7': case '8': case '9':
44  case '.': return true;
45  default: return isSignedChar(C) || isExponentChar(C);
46  }
47}
48
49static const char *BackupNumber(const char *Pos, const char *FirstChar) {
50  // If we didn't stop in the middle of a number, don't backup.
51  if (!isNumberChar(*Pos)) return Pos;
52
53  // Otherwise, return to the start of the number.
54  bool HasPeriod = false;
55  while (Pos > FirstChar && isNumberChar(Pos[-1])) {
56    // Backup over at most one period.
57    if (Pos[-1] == '.') {
58      if (HasPeriod)
59        break;
60      HasPeriod = true;
61    }
62
63    --Pos;
64    if (Pos > FirstChar && isSignedChar(Pos[0]) && !isExponentChar(Pos[-1]))
65      break;
66  }
67  return Pos;
68}
69
70/// EndOfNumber - Return the first character that is not part of the specified
71/// number.  This assumes that the buffer is null terminated, so it won't fall
72/// off the end.
73static const char *EndOfNumber(const char *Pos) {
74  while (isNumberChar(*Pos))
75    ++Pos;
76  return Pos;
77}
78
79/// CompareNumbers - compare two numbers, returning true if they are different.
80static bool CompareNumbers(const char *&F1P, const char *&F2P,
81                           const char *F1End, const char *F2End,
82                           double AbsTolerance, double RelTolerance,
83                           std::string *ErrorMsg) {
84  const char *F1NumEnd, *F2NumEnd;
85  double V1 = 0.0, V2 = 0.0;
86
87  // If one of the positions is at a space and the other isn't, chomp up 'til
88  // the end of the space.
89  while (isspace(static_cast<unsigned char>(*F1P)) && F1P != F1End)
90    ++F1P;
91  while (isspace(static_cast<unsigned char>(*F2P)) && F2P != F2End)
92    ++F2P;
93
94  // If we stop on numbers, compare their difference.
95  if (!isNumberChar(*F1P) || !isNumberChar(*F2P)) {
96    // The diff failed.
97    F1NumEnd = F1P;
98    F2NumEnd = F2P;
99  } else {
100    // Note that some ugliness is built into this to permit support for numbers
101    // that use "D" or "d" as their exponential marker, e.g. "1.234D45".  This
102    // occurs in 200.sixtrack in spec2k.
103    V1 = strtod(F1P, const_cast<char**>(&F1NumEnd));
104    V2 = strtod(F2P, const_cast<char**>(&F2NumEnd));
105
106    if (*F1NumEnd == 'D' || *F1NumEnd == 'd') {
107      // Copy string into tmp buffer to replace the 'D' with an 'e'.
108      SmallString<200> StrTmp(F1P, EndOfNumber(F1NumEnd)+1);
109      // Strange exponential notation!
110      StrTmp[static_cast<unsigned>(F1NumEnd-F1P)] = 'e';
111
112      V1 = strtod(&StrTmp[0], const_cast<char**>(&F1NumEnd));
113      F1NumEnd = F1P + (F1NumEnd-&StrTmp[0]);
114    }
115
116    if (*F2NumEnd == 'D' || *F2NumEnd == 'd') {
117      // Copy string into tmp buffer to replace the 'D' with an 'e'.
118      SmallString<200> StrTmp(F2P, EndOfNumber(F2NumEnd)+1);
119      // Strange exponential notation!
120      StrTmp[static_cast<unsigned>(F2NumEnd-F2P)] = 'e';
121
122      V2 = strtod(&StrTmp[0], const_cast<char**>(&F2NumEnd));
123      F2NumEnd = F2P + (F2NumEnd-&StrTmp[0]);
124    }
125  }
126
127  if (F1NumEnd == F1P || F2NumEnd == F2P) {
128    if (ErrorMsg) {
129      *ErrorMsg = "FP Comparison failed, not a numeric difference between '";
130      *ErrorMsg += F1P[0];
131      *ErrorMsg += "' and '";
132      *ErrorMsg += F2P[0];
133      *ErrorMsg += "'";
134    }
135    return true;
136  }
137
138  // Check to see if these are inside the absolute tolerance
139  if (AbsTolerance < std::abs(V1-V2)) {
140    // Nope, check the relative tolerance...
141    double Diff;
142    if (V2)
143      Diff = std::abs(V1/V2 - 1.0);
144    else if (V1)
145      Diff = std::abs(V2/V1 - 1.0);
146    else
147      Diff = 0;  // Both zero.
148    if (Diff > RelTolerance) {
149      if (ErrorMsg) {
150        raw_string_ostream(*ErrorMsg)
151          << "Compared: " << V1 << " and " << V2 << '\n'
152          << "abs. diff = " << std::abs(V1-V2) << " rel.diff = " << Diff << '\n'
153          << "Out of tolerance: rel/abs: " << RelTolerance << '/'
154          << AbsTolerance;
155      }
156      return true;
157    }
158  }
159
160  // Otherwise, advance our read pointers to the end of the numbers.
161  F1P = F1NumEnd;  F2P = F2NumEnd;
162  return false;
163}
164
165/// DiffFilesWithTolerance - Compare the two files specified, returning 0 if the
166/// files match, 1 if they are different, and 2 if there is a file error.  This
167/// function differs from DiffFiles in that you can specify an absolete and
168/// relative FP error that is allowed to exist.  If you specify a string to fill
169/// in for the error option, it will set the string to an error message if an
170/// error occurs, allowing the caller to distinguish between a failed diff and a
171/// file system error.
172///
173int llvm::DiffFilesWithTolerance(StringRef NameA,
174                                 StringRef NameB,
175                                 double AbsTol, double RelTol,
176                                 std::string *Error) {
177  // Now its safe to mmap the files into memory because both files
178  // have a non-zero size.
179  std::unique_ptr<MemoryBuffer> F1;
180  if (error_code ec = MemoryBuffer::getFile(NameA, F1)) {
181    if (Error)
182      *Error = ec.message();
183    return 2;
184  }
185  std::unique_ptr<MemoryBuffer> F2;
186  if (error_code ec = MemoryBuffer::getFile(NameB, F2)) {
187    if (Error)
188      *Error = ec.message();
189    return 2;
190  }
191
192  // Okay, now that we opened the files, scan them for the first difference.
193  const char *File1Start = F1->getBufferStart();
194  const char *File2Start = F2->getBufferStart();
195  const char *File1End = F1->getBufferEnd();
196  const char *File2End = F2->getBufferEnd();
197  const char *F1P = File1Start;
198  const char *F2P = File2Start;
199  uint64_t A_size = F1->getBufferSize();
200  uint64_t B_size = F2->getBufferSize();
201
202  // Are the buffers identical?  Common case: Handle this efficiently.
203  if (A_size == B_size &&
204      std::memcmp(File1Start, File2Start, A_size) == 0)
205    return 0;
206
207  // Otherwise, we are done a tolerances are set.
208  if (AbsTol == 0 && RelTol == 0) {
209    if (Error)
210      *Error = "Files differ without tolerance allowance";
211    return 1;   // Files different!
212  }
213
214  bool CompareFailed = false;
215  while (1) {
216    // Scan for the end of file or next difference.
217    while (F1P < File1End && F2P < File2End && *F1P == *F2P)
218      ++F1P, ++F2P;
219
220    if (F1P >= File1End || F2P >= File2End) break;
221
222    // Okay, we must have found a difference.  Backup to the start of the
223    // current number each stream is at so that we can compare from the
224    // beginning.
225    F1P = BackupNumber(F1P, File1Start);
226    F2P = BackupNumber(F2P, File2Start);
227
228    // Now that we are at the start of the numbers, compare them, exiting if
229    // they don't match.
230    if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error)) {
231      CompareFailed = true;
232      break;
233    }
234  }
235
236  // Okay, we reached the end of file.  If both files are at the end, we
237  // succeeded.
238  bool F1AtEnd = F1P >= File1End;
239  bool F2AtEnd = F2P >= File2End;
240  if (!CompareFailed && (!F1AtEnd || !F2AtEnd)) {
241    // Else, we might have run off the end due to a number: backup and retry.
242    if (F1AtEnd && isNumberChar(F1P[-1])) --F1P;
243    if (F2AtEnd && isNumberChar(F2P[-1])) --F2P;
244    F1P = BackupNumber(F1P, File1Start);
245    F2P = BackupNumber(F2P, File2Start);
246
247    // Now that we are at the start of the numbers, compare them, exiting if
248    // they don't match.
249    if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error))
250      CompareFailed = true;
251
252    // If we found the end, we succeeded.
253    if (F1P < File1End || F2P < File2End)
254      CompareFailed = true;
255  }
256
257  return CompareFailed;
258}
259