--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/Support/FileUtilities.cpp	Wed May 15 06:43:32 2013 +0900
@@ -0,0 +1,280 @@
+//===- Support/FileUtilities.cpp - File System Utilities ------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a family of utility functions which are useful for doing
+// various things with files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/FileUtilities.h"
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/system_error.h"
+#include <cctype>
+#include <cstdlib>
+#include <cstring>
+using namespace llvm;
+
+static bool isSignedChar(char C) {
+  return (C == '+' || C == '-');
+}
+
+static bool isExponentChar(char C) {
+  switch (C) {
+  case 'D':  // Strange exponential notation.
+  case 'd':  // Strange exponential notation.
+  case 'e':
+  case 'E': return true;
+  default: return false;
+  }
+}
+
+static bool isNumberChar(char C) {
+  switch (C) {
+  case '0': case '1': case '2': case '3': case '4':
+  case '5': case '6': case '7': case '8': case '9':
+  case '.': return true;
+  default: return isSignedChar(C) || isExponentChar(C);
+  }
+}
+
+static const char *BackupNumber(const char *Pos, const char *FirstChar) {
+  // If we didn't stop in the middle of a number, don't backup.
+  if (!isNumberChar(*Pos)) return Pos;
+
+  // Otherwise, return to the start of the number.
+  bool HasPeriod = false;
+  while (Pos > FirstChar && isNumberChar(Pos[-1])) {
+    // Backup over at most one period.
+    if (Pos[-1] == '.') {
+      if (HasPeriod)
+        break;
+      HasPeriod = true;
+    }
+
+    --Pos;
+    if (Pos > FirstChar && isSignedChar(Pos[0]) && !isExponentChar(Pos[-1]))
+      break;
+  }
+  return Pos;
+}
+
+/// EndOfNumber - Return the first character that is not part of the specified
+/// number.  This assumes that the buffer is null terminated, so it won't fall
+/// off the end.
+static const char *EndOfNumber(const char *Pos) {
+  while (isNumberChar(*Pos))
+    ++Pos;
+  return Pos;
+}
+
+/// CompareNumbers - compare two numbers, returning true if they are different.
+static bool CompareNumbers(const char *&F1P, const char *&F2P,
+                           const char *F1End, const char *F2End,
+                           double AbsTolerance, double RelTolerance,
+                           std::string *ErrorMsg) {
+  const char *F1NumEnd, *F2NumEnd;
+  double V1 = 0.0, V2 = 0.0;
+
+  // If one of the positions is at a space and the other isn't, chomp up 'til
+  // the end of the space.
+  while (isspace(static_cast<unsigned char>(*F1P)) && F1P != F1End)
+    ++F1P;
+  while (isspace(static_cast<unsigned char>(*F2P)) && F2P != F2End)
+    ++F2P;
+
+  // If we stop on numbers, compare their difference.
+  if (!isNumberChar(*F1P) || !isNumberChar(*F2P)) {
+    // The diff failed.
+    F1NumEnd = F1P;
+    F2NumEnd = F2P;
+  } else {
+    // Note that some ugliness is built into this to permit support for numbers
+    // that use "D" or "d" as their exponential marker, e.g. "1.234D45".  This
+    // occurs in 200.sixtrack in spec2k.
+    V1 = strtod(F1P, const_cast<char**>(&F1NumEnd));
+    V2 = strtod(F2P, const_cast<char**>(&F2NumEnd));
+
+    if (*F1NumEnd == 'D' || *F1NumEnd == 'd') {
+      // Copy string into tmp buffer to replace the 'D' with an 'e'.
+      SmallString<200> StrTmp(F1P, EndOfNumber(F1NumEnd)+1);
+      // Strange exponential notation!
+      StrTmp[static_cast<unsigned>(F1NumEnd-F1P)] = 'e';
+
+      V1 = strtod(&StrTmp[0], const_cast<char**>(&F1NumEnd));
+      F1NumEnd = F1P + (F1NumEnd-&StrTmp[0]);
+    }
+
+    if (*F2NumEnd == 'D' || *F2NumEnd == 'd') {
+      // Copy string into tmp buffer to replace the 'D' with an 'e'.
+      SmallString<200> StrTmp(F2P, EndOfNumber(F2NumEnd)+1);
+      // Strange exponential notation!
+      StrTmp[static_cast<unsigned>(F2NumEnd-F2P)] = 'e';
+
+      V2 = strtod(&StrTmp[0], const_cast<char**>(&F2NumEnd));
+      F2NumEnd = F2P + (F2NumEnd-&StrTmp[0]);
+    }
+  }
+
+  if (F1NumEnd == F1P || F2NumEnd == F2P) {
+    if (ErrorMsg) {
+      *ErrorMsg = "FP Comparison failed, not a numeric difference between '";
+      *ErrorMsg += F1P[0];
+      *ErrorMsg += "' and '";
+      *ErrorMsg += F2P[0];
+      *ErrorMsg += "'";
+    }
+    return true;
+  }
+
+  // Check to see if these are inside the absolute tolerance
+  if (AbsTolerance < std::abs(V1-V2)) {
+    // Nope, check the relative tolerance...
+    double Diff;
+    if (V2)
+      Diff = std::abs(V1/V2 - 1.0);
+    else if (V1)
+      Diff = std::abs(V2/V1 - 1.0);
+    else
+      Diff = 0;  // Both zero.
+    if (Diff > RelTolerance) {
+      if (ErrorMsg) {
+        raw_string_ostream(*ErrorMsg)
+          << "Compared: " << V1 << " and " << V2 << '\n'
+          << "abs. diff = " << std::abs(V1-V2) << " rel.diff = " << Diff << '\n'
+          << "Out of tolerance: rel/abs: " << RelTolerance << '/'
+          << AbsTolerance;
+      }
+      return true;
+    }
+  }
+
+  // Otherwise, advance our read pointers to the end of the numbers.
+  F1P = F1NumEnd;  F2P = F2NumEnd;
+  return false;
+}
+
+/// DiffFilesWithTolerance - Compare the two files specified, returning 0 if the
+/// files match, 1 if they are different, and 2 if there is a file error.  This
+/// function differs from DiffFiles in that you can specify an absolete and
+/// relative FP error that is allowed to exist.  If you specify a string to fill
+/// in for the error option, it will set the string to an error message if an
+/// error occurs, allowing the caller to distinguish between a failed diff and a
+/// file system error.
+///
+int llvm::DiffFilesWithTolerance(const sys::PathWithStatus &FileA,
+                                 const sys::PathWithStatus &FileB,
+                                 double AbsTol, double RelTol,
+                                 std::string *Error) {
+  const sys::FileStatus *FileAStat = FileA.getFileStatus(false, Error);
+  if (!FileAStat)
+    return 2;
+  const sys::FileStatus *FileBStat = FileB.getFileStatus(false, Error);
+  if (!FileBStat)
+    return 2;
+
+  // Check for zero length files because some systems croak when you try to
+  // mmap an empty file.
+  size_t A_size = FileAStat->getSize();
+  size_t B_size = FileBStat->getSize();
+
+  // If they are both zero sized then they're the same
+  if (A_size == 0 && B_size == 0)
+    return 0;
+
+  // If only one of them is zero sized then they can't be the same
+  if ((A_size == 0 || B_size == 0)) {
+    if (Error)
+      *Error = "Files differ: one is zero-sized, the other isn't";
+    return 1;
+  }
+
+  // Now its safe to mmap the files into memory because both files
+  // have a non-zero size.
+  OwningPtr<MemoryBuffer> F1;
+  if (error_code ec = MemoryBuffer::getFile(FileA.c_str(), F1)) {
+    if (Error)
+      *Error = ec.message();
+    return 2;
+  }
+  OwningPtr<MemoryBuffer> F2;
+  if (error_code ec = MemoryBuffer::getFile(FileB.c_str(), F2)) {
+    if (Error)
+      *Error = ec.message();
+    return 2;
+  }
+
+  // Okay, now that we opened the files, scan them for the first difference.
+  const char *File1Start = F1->getBufferStart();
+  const char *File2Start = F2->getBufferStart();
+  const char *File1End = F1->getBufferEnd();
+  const char *File2End = F2->getBufferEnd();
+  const char *F1P = File1Start;
+  const char *F2P = File2Start;
+
+  // Are the buffers identical?  Common case: Handle this efficiently.
+  if (A_size == B_size &&
+      std::memcmp(File1Start, File2Start, A_size) == 0)
+    return 0;
+
+  // Otherwise, we are done a tolerances are set.
+  if (AbsTol == 0 && RelTol == 0) {
+    if (Error)
+      *Error = "Files differ without tolerance allowance";
+    return 1;   // Files different!
+  }
+
+  bool CompareFailed = false;
+  while (1) {
+    // Scan for the end of file or next difference.
+    while (F1P < File1End && F2P < File2End && *F1P == *F2P)
+      ++F1P, ++F2P;
+
+    if (F1P >= File1End || F2P >= File2End) break;
+
+    // Okay, we must have found a difference.  Backup to the start of the
+    // current number each stream is at so that we can compare from the
+    // beginning.
+    F1P = BackupNumber(F1P, File1Start);
+    F2P = BackupNumber(F2P, File2Start);
+
+    // Now that we are at the start of the numbers, compare them, exiting if
+    // they don't match.
+    if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error)) {
+      CompareFailed = true;
+      break;
+    }
+  }
+
+  // Okay, we reached the end of file.  If both files are at the end, we
+  // succeeded.
+  bool F1AtEnd = F1P >= File1End;
+  bool F2AtEnd = F2P >= File2End;
+  if (!CompareFailed && (!F1AtEnd || !F2AtEnd)) {
+    // Else, we might have run off the end due to a number: backup and retry.
+    if (F1AtEnd && isNumberChar(F1P[-1])) --F1P;
+    if (F2AtEnd && isNumberChar(F2P[-1])) --F2P;
+    F1P = BackupNumber(F1P, File1Start);
+    F2P = BackupNumber(F2P, File2Start);
+
+    // Now that we are at the start of the numbers, compare them, exiting if
+    // they don't match.
+    if (CompareNumbers(F1P, F2P, File1End, File2End, AbsTol, RelTol, Error))
+      CompareFailed = true;
+
+    // If we found the end, we succeeded.
+    if (F1P < File1End || F2P < File2End)
+      CompareFailed = true;
+  }
+
+  return CompareFailed;
+}