FileUtilities.cpp revision 263508 
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/OwningPtr.h"
17#include "llvm/ADT/SmallString.h"
18#include "llvm/Support/MemoryBuffer.h"
19#include "llvm/Support/Path.h"
20#include "llvm/Support/raw_ostream.h"
21#include "llvm/Support/system_error.h"
22#include <cctype>
23#include <cstdlib>
24#include <cstring>
25using namespace llvm;
26
27static bool isSignedChar(char C) {
28  return (C == '+' || C == '-');
29}
30
31static bool isExponentChar(char C) {
32  switch (C) {
33  case 'D':  // Strange exponential notation.
34  case 'd':  // Strange exponential notation.
35  case 'e':
36  case 'E': return true;
37  default: return false;
38  }
39}
40
41static bool isNumberChar(char C) {
42  switch (C) {
43  case '0': case '1': case '2': case '3': case '4':
44  case '5': case '6': case '7': case '8': case '9':
45  case '.': return true;
46  default: return isSignedChar(C) || isExponentChar(C);
47  }
48}
49
50static const char *BackupNumber(const char *Pos, const char *FirstChar) {
51  // If we didn't stop in the middle of a number, don't backup.
52  if (!isNumberChar(*Pos)) return Pos;
53
54  // Otherwise, return to the start of the number.
55  bool HasPeriod = false;
56  while (Pos > FirstChar && isNumberChar(Pos[-1])) {
57    // Backup over at most one period.
58    if (Pos[-1] == '.') {
59      if (HasPeriod)
60        break;
61      HasPeriod = true;
62    }
63
64    --Pos;
65    if (Pos > FirstChar && isSignedChar(Pos[0]) && !isExponentChar(Pos[-1]))
66      break;
67  }
68  return Pos;
69}
70
71/// EndOfNumber - Return the first character that is not part of the specified
72/// number.  This assumes that the buffer is null terminated, so it won't fall
73/// off the end.
74static const char *EndOfNumber(const char *Pos) {
75  while (isNumberChar(*Pos))
76    ++Pos;
77  return Pos;
78}
79
80/// CompareNumbers - compare two numbers, returning true if they are different.
81static bool CompareNumbers(const char *&F1P, const char *&F2P,
82                           const char *F1End, const char *F2End,
83                           double AbsTolerance, double RelTolerance,
84                           std::string *ErrorMsg) {
85  const char *F1NumEnd, *F2NumEnd;
86  double V1 = 0.0, V2 = 0.0;
87
88  // If one of the positions is at a space and the other isn't, chomp up 'til
89  // the end of the space.
90  while (isspace(static_cast<unsigned char>(*F1P)) && F1P != F1End)
91    ++F1P;
92  while (isspace(static_cast<unsigned char>(*F2P)) && F2P != F2End)
93    ++F2P;
94
95  // If we stop on numbers, compare their difference.
96  if (!isNumberChar(*F1P) || !isNumberChar(*F2P)) {
97    // The diff failed.
98    F1NumEnd = F1P;
99    F2NumEnd = F2P;
100  } else {
101    // Note that some ugliness is built into this to permit support for numbers
102    // that use "D" or "d" as their exponential marker, e.g. "1.234D45".  This
103    // occurs in 200.sixtrack in spec2k.
104    V1 = strtod(F1P, const_cast<char**>(&F1NumEnd));
105    V2 = strtod(F2P, const_cast<char**>(&F2NumEnd));
106
107    if (*F1NumEnd == 'D' || *F1NumEnd == 'd') {
108      // Copy string into tmp buffer to replace the 'D' with an 'e'.
109      SmallString<200> StrTmp(F1P, EndOfNumber(F1NumEnd)+1);
110      // Strange exponential notation!
111      StrTmp[static_cast<unsigned>(F1NumEnd-F1P)] = 'e';
112
113      V1 = strtod(&StrTmp[0], const_cast<char**>(&F1NumEnd));
114      F1NumEnd = F1P + (F1NumEnd-&StrTmp[0]);
115    }
116
117    if (*F2NumEnd == 'D' || *F2NumEnd == 'd') {
118      // Copy string into tmp buffer to replace the 'D' with an 'e'.
119      SmallString<200> StrTmp(F2P, EndOfNumber(F2NumEnd)+1);
120      // Strange exponential notation!
121      StrTmp[static_cast<unsigned>(F2NumEnd-F2P)] = 'e';
122
123      V2 = strtod(&StrTmp[0], const_cast<char**>(&F2NumEnd));
124      F2NumEnd = F2P + (F2NumEnd-&StrTmp[0]);
125    }
126  }
127
128  if (F1NumEnd == F1P || F2NumEnd == F2P) {
129    if (ErrorMsg) {
130      *ErrorMsg = "FP Comparison failed, not a numeric difference between '";
131      *ErrorMsg += F1P[0];
132      *ErrorMsg += "' and '";
133      *ErrorMsg += F2P[0];
134      *ErrorMsg += "'";
135    }
136    return true;
137  }
138
139  // Check to see if these are inside the absolute tolerance
140  if (AbsTolerance < std::abs(V1-V2)) {
141    // Nope, check the relative tolerance...
142    double Diff;
143    if (V2)
144      Diff = std::abs(V1/V2 - 1.0);
145    else if (V1)
146      Diff = std::abs(V2/V1 - 1.0);
147    else
148      Diff = 0;  // Both zero.
149    if (Diff > RelTolerance) {
150      if (ErrorMsg) {
151        raw_string_ostream(*ErrorMsg)
152          << "Compared: " << V1 << " and " << V2 << '\n'
153          << "abs. diff = " << std::abs(V1-V2) << " rel.diff = " << Diff << '\n'
154          << "Out of tolerance: rel/abs: " << RelTolerance << '/'
155          << AbsTolerance;
156      }
157      return true;
158    }
159  }
160
161  // Otherwise, advance our read pointers to the end of the numbers.
162  F1P = F1NumEnd;  F2P = F2NumEnd;
163  return false;
164}
165
166/// DiffFilesWithTolerance - Compare the two files specified, returning 0 if the
167/// files match, 1 if they are different, and 2 if there is a file error.  This
168/// function differs from DiffFiles in that you can specify an absolete and
169/// relative FP error that is allowed to exist.  If you specify a string to fill
170/// in for the error option, it will set the string to an error message if an
171/// error occurs, allowing the caller to distinguish between a failed diff and a
172/// file system error.
173///
174int llvm::DiffFilesWithTolerance(StringRef NameA,
175                                 StringRef NameB,
176                                 double AbsTol, double RelTol,
177                                 std::string *Error) {
178  // Now its safe to mmap the files into memory because both files
179  // have a non-zero size.
180  OwningPtr<MemoryBuffer> F1;
181  if (error_code ec = MemoryBuffer::getFile(NameA, F1)) {
182    if (Error)
183      *Error = ec.message();
184    return 2;
185  }
186  OwningPtr<MemoryBuffer> F2;
187  if (error_code ec = MemoryBuffer::getFile(NameB, F2)) {
188    if (Error)
189      *Error = ec.message();
190    return 2;
191  }
192
193  // Okay, now that we opened the files, scan them for the first difference.
194  const char *File1Start = F1->getBufferStart();
195  const char *File2Start = F2->getBufferStart();
196  const char *File1End = F1->getBufferEnd();
197  const char *File2End = F2->getBufferEnd();
198  const char *F1P = File1Start;
199  const char *F2P = File2Start;
200  uint64_t A_size = F1->getBufferSize();
201  uint64_t B_size = F2->getBufferSize();
202
203  // Are the buffers identical?  Common case: Handle this efficiently.
204  if (A_size == B_size &&
205      std::memcmp(File1Start, File2Start, A_size) == 0)
206    return 0;
207
208  // Otherwise, we are done a tolerances are set.
209  if (AbsTol == 0 && RelTol == 0) {
210    if (Error)
211      *Error = "Files differ without tolerance allowance";
212    return 1;   // Files different!
213  }
214
215  bool CompareFailed = false;
216  while (1) {
217    // Scan for the end of file or next difference.
218    while (F1P < File1End && F2P < File2End && *F1P == *F2P)
219      ++F1P, ++F2P;
220
221    if (F1P >= File1End || F2P >= File2End) break;
222
223    // Okay, we must have found a difference.  Backup to the start of the
224    // current number each stream is at so that we can compare from the
225    // beginning.
226    F1P = BackupNumber(F1P, File1Start);
227    F2P = BackupNumber(F2P, File2Start);
228
229    // Now that we are at the start of the numbers, compare them, exiting if
230    // they don't match.
231    if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error)) {
232      CompareFailed = true;
233      break;
234    }
235  }
236
237  // Okay, we reached the end of file.  If both files are at the end, we
238  // succeeded.
239  bool F1AtEnd = F1P >= File1End;
240  bool F2AtEnd = F2P >= File2End;
241  if (!CompareFailed && (!F1AtEnd || !F2AtEnd)) {
242    // Else, we might have run off the end due to a number: backup and retry.
243    if (F1AtEnd && isNumberChar(F1P[-1])) --F1P;
244    if (F2AtEnd && isNumberChar(F2P[-1])) --F2P;
245    F1P = BackupNumber(F1P, File1Start);
246    F2P = BackupNumber(F2P, File2Start);
247
248    // Now that we are at the start of the numbers, compare them, exiting if
249    // they don't match.
250    if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error))
251      CompareFailed = true;
252
253    // If we found the end, we succeeded.
254    if (F1P < File1End || F2P < File2End)
255      CompareFailed = true;
256  }
257
258  return CompareFailed;
259}
260