Reverted r143600 - selector reference change

[oota-llvm.git] / lib / Support / StringRef.cpp

diff --git a/lib/Support/StringRef.cpp b/lib/Support/StringRef.cpp
index 066e7743ae44b202bff234cf85d3ef11369a427d..576b95f6a4e3c339131b15ca9b65d5366ae00409 100644 (file)
--- a/lib/Support/StringRef.cpp
+++ b/lib/Support/StringRef.cpp
@@ -29,27 +29,6 @@ static bool ascii_isdigit(char x) {
   return x >= '0' && x <= '9';
 }
 
-/// compare - Compare two strings; the result is -1, 0, or 1 if this string
-/// is lexicographically less than, equal to, or greater than the \arg RHS.
-/// This is different than compare with no size specified as it only 
-/// compares at most the first n bytes.
-int StringRef::compare(StringRef RHS, size_t n) const {
-  // Check the prefix for a mismatch.
-  size_t maxToCmp = min(Length, RHS.Length);
-  maxToCmp = min(maxToCmp, n);
-  if (int Res = memcmp(Data, RHS.Data, maxToCmp))
-    return Res < 0 ? -1 : 1;
-  
-  // Otherwise the prefixes match, so we only need to check the lengths.
-  // Be mindful that if the n is less than or equal to the length of either
-  // string, that is the same as the strings matching because in that case
-  // we only care about the prefix.
-  if (((n <= Length) && (n <= RHS.Length)) || 
-      (Length == RHS.Length))
-    return 0;
-  return Length < RHS.Length ? -1 : 1;
-}
-
 /// compare_lower - Compare strings, ignoring case.
 int StringRef::compare_lower(StringRef RHS) const {
   for (size_t I = 0, E = min(Length, RHS.Length); I != E; ++I) {
@@ -67,12 +46,12 @@ int StringRef::compare_lower(StringRef RHS) const {
 /// compare_numeric - Compare strings, handle embedded numbers.
 int StringRef::compare_numeric(StringRef RHS) const {
   for (size_t I = 0, E = min(Length, RHS.Length); I != E; ++I) {
-    if (Data[I] == RHS.Data[I])
-      continue;
+    // Check for sequences of digits.
     if (ascii_isdigit(Data[I]) && ascii_isdigit(RHS.Data[I])) {
-      // The longer sequence of numbers is larger. This doesn't really handle
-      // prefixed zeros well.
-      for (size_t J = I+1; J != E+1; ++J) {
+      // The longer sequence of numbers is considered larger.
+      // This doesn't really handle prefixed zeros well.
+      size_t J;
+      for (J = I + 1; J != E + 1; ++J) {
         bool ld = J < Length && ascii_isdigit(Data[J]);
         bool rd = J < RHS.Length && ascii_isdigit(RHS.Data[J]);
         if (ld != rd)
@@ -80,8 +59,15 @@ int StringRef::compare_numeric(StringRef RHS) const {
         if (!rd)
           break;
       }
+      // The two number sequences have the same length (J-I), just memcmp them.
+      if (int Res = compareMemory(Data + I, RHS.Data + I, J - I))
+        return Res < 0 ? -1 : 1;
+      // Identical number sequences, continue search after the numbers.
+      I = J - 1;
+      continue;
     }
-    return (unsigned char)Data[I] < (unsigned char)RHS.Data[I] ? -1 : 1;
+    if (Data[I] != RHS.Data[I])
+      return (unsigned char)Data[I] < (unsigned char)RHS.Data[I] ? -1 : 1;
   }
   if (Length == RHS.Length)
     return 0;
@@ -158,9 +144,35 @@ size_t StringRef::find(StringRef Str, size_t From) const {
   size_t N = Str.size();
   if (N > Length)
     return npos;
-  for (size_t e = Length - N + 1, i = min(From, e); i != e; ++i)
-    if (substr(i, N).equals(Str))
-      return i;
+
+  // For short haystacks or unsupported needles fall back to the naive algorithm
+  if (Length < 16 || N > 255 || N == 0) {
+    for (size_t e = Length - N + 1, i = min(From, e); i != e; ++i)
+      if (substr(i, N).equals(Str))
+        return i;
+    return npos;
+  }
+
+  if (From >= Length)
+    return npos;
+
+  // Build the bad char heuristic table, with uint8_t to reduce cache thrashing.
+  uint8_t BadCharSkip[256];
+  std::memset(BadCharSkip, N, 256);
+  for (unsigned i = 0; i != N-1; ++i)
+    BadCharSkip[(uint8_t)Str[i]] = N-1-i;
+
+  unsigned Len = Length-From, Pos = From;
+  while (Len >= N) {
+    if (substr(Pos, N).equals(Str)) // See if this is the correct substring.
+      return Pos;
+
+    // Otherwise skip the appropriate number of bytes.
+    uint8_t Skip = BadCharSkip[(uint8_t)(*this)[Pos+N-1]];
+    Len -= Skip;
+    Pos += Skip;
+  }
+
   return npos;
 }