Add a new method, refactored out of fpcmp

llvm-svn: 19766

lib/Support/FileUtilities.cpp

@@ -14,6 +14,9 @@
 
 #include "llvm/Support/FileUtilities.h"
 #include "llvm/System/Path.h"
+#include "llvm/System/MappedFile.h"
+#include "llvm/ADT/StringExtras.h"
+#include <cmath>
 #include <fstream>
 #include <iostream>
 
@@ -64,3 +67,184 @@ void llvm::MoveFileOverIfUpdated(const std::string &New,
     std::remove(New.c_str());
   }  
 }
+
+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 '.': case '+': case '-':
+  case 'e':
+  case 'E': return true;
+  default: return false;
+  }
+}
+
+static char *BackupNumber(char *Pos, 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.
+  while (Pos > FirstChar && isNumberChar(Pos[-1]))
+    --Pos;
+  return Pos;
+}
+
+/// CompareNumbers - compare two numbers, returning true if they are different.
+static bool CompareNumbers(char *&F1P, char *&F2P, char *F1End, char *F2End,
+                           double AbsTolerance, double RelTolerance,
+                           std::string *ErrorMsg) {
+  char *F1NumEnd, *F2NumEnd;
+  double V1 = 0.0, V2 = 0.0; 
+  // If we stop on numbers, compare their difference.
+  if (isNumberChar(*F1P) && isNumberChar(*F2P)) {
+    V1 = strtod(F1P, &F1NumEnd);
+    V2 = strtod(F2P, &F2NumEnd);
+  } else {
+    // Otherwise, the diff failed.
+    F1NumEnd = F1P;
+    F2NumEnd = F2P;
+  }
+
+  if (F1NumEnd == F1P || F2NumEnd == F2P) {
+    if (ErrorMsg) *ErrorMsg = "Comparison failed, not a numeric difference.";
+    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) {
+        *ErrorMsg = "Compared: " + ftostr(V1) + " and " + ftostr(V2) +
+                    ": diff = " + ftostr(Diff) + "\n";
+        *ErrorMsg += "Out of tolerance: rel/abs: " + ftostr(RelTolerance) +
+                     "/" + ftostr(AbsTolerance);
+      }
+      return true;
+    }
+  }
+
+  // Otherwise, advance our read pointers to the end of the numbers.
+  F1P = F1NumEnd;  F2P = F2NumEnd;
+  return false;
+}
+
+// PadFileIfNeeded - If the files are not identical, we will have to be doing
+// numeric comparisons in here.  There are bad cases involved where we (i.e.,
+// strtod) might run off the beginning or end of the file if it starts or ends
+// with a number.  Because of this, if needed, we pad the file so that it starts
+// and ends with a null character.
+static void PadFileIfNeeded(char *&FileStart, char *&FileEnd, char *&FP) {
+  if (isNumberChar(FileStart[0]) || isNumberChar(FileEnd[-1])) {
+    unsigned FileLen = FileEnd-FileStart;
+    char *NewFile = new char[FileLen+2];
+    NewFile[0] = 0;              // Add null padding
+    NewFile[FileLen+1] = 0;      // Add null padding
+    memcpy(NewFile+1, FileStart, FileLen);
+    FP = NewFile+(FP-FileStart)+1;
+    FileStart = NewFile+1;
+    FileEnd = FileStart+FileLen;
+  }
+}
+
+/// 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 std::string &FileA,
+                                 const std::string &FileB,
+                                 double AbsTol, double RelTol,
+                                 std::string *Error) {
+  try {
+    // Map in the files into memory.
+    sys::MappedFile F1((sys::Path(FileA)));
+    sys::MappedFile F2((sys::Path(FileB)));
+    F1.map();
+    F2.map();
+
+    // Okay, now that we opened the files, scan them for the first difference.
+    char *File1Start = F1.charBase();
+    char *File2Start = F2.charBase();
+    char *File1End = File1Start+F1.size();
+    char *File2End = File2Start+F2.size();
+    char *F1P = File1Start;
+    char *F2P = File2Start;
+
+    // Scan for the end of file or first difference.
+    while (F1P < File1End && F2P < File2End && *F1P == *F2P)
+      ++F1P, ++F2P;
+
+    // Common case: identifical files.
+    if (F1P == File1End && F2P == File2End) return 0;
+
+    char *OrigFile1Start = File1Start;
+    char *OrigFile2Start = File2Start;
+
+    // If the files need padding, do so now.
+    PadFileIfNeeded(File1Start, File1End, F1P);
+    PadFileIfNeeded(File2Start, File2End, F2P);
+    
+    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;
+    }
+
+    if (OrigFile1Start != File1Start)
+      delete[] File1Start;
+    if (OrigFile2Start != File2Start)
+      delete[] File2Start;
+    return CompareFailed;
+  } catch (const std::string &Msg) {
+    if (Error) *Error = Msg;
+    return 2;
+  }
+}