Run string replace regexp with function in C++ code loop.

src/runtime.cc

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1546 matching lines @@
   return CharFromCode(code);
 }
 
 
 static Object* Runtime_CharFromCode(Arguments args) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 1);
   return CharFromCode(args[0]);
 }
 
+
+class FixedArrayBuilder {
+ public:
+  explicit FixedArrayBuilder(int initial_capacity)
+      : array_(Factory::NewFixedArrayWithHoles(initial_capacity)),
+        length_(0) {
+    // Require a non-zero initial size. Ensures that doubling the size to
+    // extend the array will work.
+    ASSERT(initial_capacity > 0);
+  }
+
+  explicit FixedArrayBuilder(Handle<FixedArray> backing_store)
+      : array_(backing_store),
+        length_(0) {
+    // Require a non-zero initial size. Ensures that doubling the size to
+    // extend the array will work.
+    ASSERT(backing_store->length() > 0);
+  }
+
+  bool HasCapacity(int elements) {
+    int length = array_->length();
+    int required_length = length_ + elements;
+    return (length >= required_length);
+  }
+
+  void EnsureCapacity(int elements) {
+    int length = array_->length();
+    int required_length = length_ + elements;
+    if (length < required_length) {
+      int new_length = length;
+      do {
+        new_length *= 2;
+      } while (new_length < required_length);
+      Handle<FixedArray> extended_array =
+          Factory::NewFixedArrayWithHoles(new_length);
+      array_->CopyTo(0, *extended_array, 0, length_);
+      array_ = extended_array;
+    }
+  }
+
+  void Add(Object* value) {
+    ASSERT(length_ < capacity());
+    array_->set(length_, value);
+    length_++;
+  }
+
+  void Add(Smi* value) {
+    ASSERT(length_ < capacity());
+    array_->set(length_, value);
+    length_++;
+  }
+
+  inline Handle<FixedArray> array() {

[fschneider, 2010/03/25 10:26:06]

I don't know enough how C++ compilers treat the inline keyword, but I'm not sure
if we need inline here if the function is defined at the declaration. 

[Lasse Reichstein, 2010/03/26 11:18:26]

I think you are right. Inlining is default in this case.

+    return array_;
+  }
+
+  inline int length() {
+    return length_;
+  }
+
+  inline int capacity() {
+    return array_->length();
+  }
+
+  inline Handle<JSArray> ToJSArray() {
+    Handle<JSArray> result_array = Factory::NewJSArrayWithElements(array_);
+    result_array->set_length(Smi::FromInt(length_));
+    return result_array;
+  }
+
+  inline Handle<JSArray> ToJSArray(Handle<JSArray> target_array) {
+    target_array->set_elements(*array_);
+    target_array->set_length(Smi::FromInt(length_));
+    return target_array;
+  }
+
+ private:
+  Handle<FixedArray> array_;
+  int length_;
+};
+
+
 // Forward declarations.
 static const int kStringBuilderConcatHelperLengthBits = 11;

[fschneider, 2010/03/25 10:26:06]

No need for static here. It is the default for C++ top-level const declarations.

[Lasse Reichstein, 2010/03/26 11:18:26]

Fixed.

 static const int kStringBuilderConcatHelperPositionBits = 19;
 
 template <typename schar>
 static inline void StringBuilderConcatHelper(String*,
                                              schar*,
                                              FixedArray*,
                                              int);
 
 typedef BitField<int, 0, 11> StringBuilderSubstringLength;

[fschneider, 2010/03/25 10:26:06]

Would be better to use the defined constants here. Although the line may get too
long then...

[Lasse Reichstein, 2010/03/26 11:18:26]

Very long, but changed anyway.

 typedef BitField<int, 11, 19> StringBuilderSubstringPosition;
 
+
 class ReplacementStringBuilder {
  public:
   ReplacementStringBuilder(Handle<String> subject, int estimated_part_count)
-      : subject_(subject),
-        parts_(Factory::NewFixedArray(estimated_part_count)),
-        part_count_(0),
+      : array_builder_(estimated_part_count),
+        subject_(subject),
         character_count_(0),
         is_ascii_(subject->IsAsciiRepresentation()) {
     // Require a non-zero initial size. Ensures that doubling the size to
     // extend the array will work.
     ASSERT(estimated_part_count > 0);
   }
 
-  void EnsureCapacity(int elements) {
-    int length = parts_->length();
-    int required_length = part_count_ + elements;
-    if (length < required_length) {
-      int new_length = length;
-      do {
-        new_length *= 2;
-      } while (new_length < required_length);
-      Handle<FixedArray> extended_array =
-          Factory::NewFixedArray(new_length);
-      parts_->CopyTo(0, *extended_array, 0, part_count_);
-      parts_ = extended_array;
-    }
-  }
-
-  void AddSubjectSlice(int from, int to) {
+  static inline void AddSubjectSlice(FixedArrayBuilder* builder,
+                                     int from,
+                                     int to) {
     ASSERT(from >= 0);
     int length = to - from;
     ASSERT(length > 0);
-    // Can we encode the slice in 11 bits for length and 19 bits for
-    // start position - as used by StringBuilderConcatHelper?
     if (StringBuilderSubstringLength::is_valid(length) &&
         StringBuilderSubstringPosition::is_valid(from)) {
       int encoded_slice = StringBuilderSubstringLength::encode(length) |
           StringBuilderSubstringPosition::encode(from);
-      AddElement(Smi::FromInt(encoded_slice));
+      builder->Add(Smi::FromInt(encoded_slice));
     } else {
       // Otherwise encode as two smis.
-      AddElement(Smi::FromInt(-length));
-      AddElement(Smi::FromInt(from));
+      builder->Add(Smi::FromInt(-length));
+      builder->Add(Smi::FromInt(from));
     }
-    IncrementCharacterCount(length);
   }
 
 
+  void EnsureCapacity(int elements) {
+    array_builder_.EnsureCapacity(elements);
+  }
+
+
+  void AddSubjectSlice(int from, int to) {
+    AddSubjectSlice(&array_builder_, from, to);
+    // Can we encode the slice in 11 bits for length and 19 bits for
+    // start position - as used by StringBuilderConcatHelper?
+    IncrementCharacterCount(to - from);
+  }
+
+
   void AddString(Handle<String> string) {
     int length = string->length();
     ASSERT(length > 0);
     AddElement(*string);
     if (!string->IsAsciiRepresentation()) {
       is_ascii_ = false;
     }
     IncrementCharacterCount(length);
   }
 
 
   Handle<String> ToString() {
-    if (part_count_ == 0) {
+    if (array_builder_.length() == 0) {
       return Factory::empty_string();
     }
 
     Handle<String> joined_string;
     if (is_ascii_) {
       joined_string = NewRawAsciiString(character_count_);
       AssertNoAllocation no_alloc;
       SeqAsciiString* seq = SeqAsciiString::cast(*joined_string);
       char* char_buffer = seq->GetChars();
       StringBuilderConcatHelper(*subject_,
                                 char_buffer,
-                                *parts_,
-                                part_count_);
+                                *array_builder_.array(),
+                                array_builder_.length());
     } else {
       // Non-ASCII.
       joined_string = NewRawTwoByteString(character_count_);
       AssertNoAllocation no_alloc;
       SeqTwoByteString* seq = SeqTwoByteString::cast(*joined_string);
       uc16* char_buffer = seq->GetChars();
       StringBuilderConcatHelper(*subject_,
                                 char_buffer,
-                                *parts_,
-                                part_count_);
+                                *array_builder_.array(),
+                                array_builder_.length());
     }
     return joined_string;
   }
 
 
   void IncrementCharacterCount(int by) {
     if (character_count_ > String::kMaxLength - by) {
       V8::FatalProcessOutOfMemory("String.replace result too large.");
     }
     character_count_ += by;
   }
 
+  Handle<JSArray> GetParts() {
+    Handle<JSArray> result =
+        Factory::NewJSArrayWithElements(array_builder_.array());
+    result->set_length(Smi::FromInt(array_builder_.length()));
+    return result;
+  }
+
  private:
 

[fschneider, 2010/03/25 10:26:06]

Extra empty line.

   Handle<String> NewRawAsciiString(int size) {
     CALL_HEAP_FUNCTION(Heap::AllocateRawAsciiString(size), String);
   }
 
 
   Handle<String> NewRawTwoByteString(int size) {
     CALL_HEAP_FUNCTION(Heap::AllocateRawTwoByteString(size), String);
   }
 
 
   void AddElement(Object* element) {
     ASSERT(element->IsSmi() || element->IsString());
-    ASSERT(parts_->length() > part_count_);
-    parts_->set(part_count_, element);
-    part_count_++;
+    ASSERT(array_builder_.capacity() > array_builder_.length());
+    array_builder_.Add(element);
   }
 
+  FixedArrayBuilder array_builder_;
   Handle<String> subject_;
-  Handle<FixedArray> parts_;
-  int part_count_;
   int character_count_;
   bool is_ascii_;
 };
 
 
 class CompiledReplacement {
  public:
   CompiledReplacement()
       : parts_(1), replacement_substrings_(0) {}
 
@@ skipping 387 matching lines @@
 
   ASSERT(last_match_info->HasFastElements());
 
   return StringReplaceRegExpWithString(subject,
                                        regexp,
                                        replacement,
                                        last_match_info);
 }
 
 
-
 // Cap on the maximal shift in the Boyer-Moore implementation. By setting a
 // limit, we can fix the size of tables.
 static const int kBMMaxShift = 0xff;
 // Reduce alphabet to this size.
 static const int kBMAlphabetSize = 0x100;
 // For patterns below this length, the skip length of Boyer-Moore is too short
 // to compensate for the algorithmic overhead compared to simple brute force.
 static const int kBMMinPatternLength = 5;
 
 // Holds the two buffers used by Boyer-Moore string search's Good Suffix
@@ skipping 743 matching lines @@
     int from = offsets.at(i * 2);
     int to = offsets.at(i * 2 + 1);
     elements->set(i, *Factory::NewSubString(subject, from, to));
   }
   Handle<JSArray> result = Factory::NewJSArrayWithElements(elements);
   result->set_length(Smi::FromInt(matches));
   return *result;
 }
 
 
+// Two smis before and after the match, for very long strings.
+static const int kMaxBuilderEntriesPerRegExpMatch = 5;

[fschneider, 2010/03/25 10:26:06]

No need for static here either.

[Lasse Reichstein, 2010/03/26 11:18:26]

Removed.

+
+
+static void SetLastMatchInfoNoCaptures(Handle<String> subject,
+                                       Handle<JSArray> last_match_info,
+                                       int match_start,
+                                       int match_end) {
+  // Fill last_match_info with a single capture.
+  last_match_info->EnsureSize(2 + RegExpImpl::kLastMatchOverhead);
+  AssertNoAllocation no_gc;
+  FixedArray* elements = FixedArray::cast(last_match_info->elements());
+  RegExpImpl::SetLastCaptureCount(elements, 2);
+  RegExpImpl::SetLastInput(elements, *subject);
+  RegExpImpl::SetLastSubject(elements, *subject);
+  RegExpImpl::SetCapture(elements, 0, match_start);
+  RegExpImpl::SetCapture(elements, 1, match_end);
+}
+
+
+template <typename schar>
+static bool SearchCharMultiple(Vector<schar> subject,
+                               String* pattern,
+                               schar pattern_char,
+                               FixedArrayBuilder* builder,
+                               int* match_pos) {
+  // Position of last match.
+  int pos = *match_pos;
+  int subject_length = subject.length();
+  while (pos < subject_length) {
+    int match_end = pos + 1;
+    if (!builder->HasCapacity(kMaxBuilderEntriesPerRegExpMatch)) {
+      *match_pos = pos;
+      return false;
+    }
+    int new_pos = SingleCharIndexOf(subject, pattern_char, match_end);
+    if (new_pos >= 0) {

[fschneider, 2010/03/25 10:26:06]

More compact if you reverse the condition:

if (new_pos < 0) break;
...

[Lasse Reichstein, 2010/03/26 11:18:26]

I want to have the "fast case" as the first branch of the if.
I guess the compiler would generate the exact same code in both cases, though. 
I'll keep this for now.

+      // A match.

[fschneider, 2010/03/25 10:26:06]

Complete sentence for whole-line comments.

+      if (new_pos > match_end) {
+        ReplacementStringBuilder::AddSubjectSlice(builder, match_end, new_pos);
+      }
+      pos = new_pos;
+      builder->Add(pattern);
+    } else {
+      break;
+    }
+  }
+  if (pos + 1 < subject_length) {
+    ReplacementStringBuilder::AddSubjectSlice(builder, pos + 1, subject_length);
+  }
+  *match_pos = pos;
+  return true;
+}
+
+
+static bool SearchCharMultiple(Handle<String> subject,
+                               Handle<String> pattern,
+                               Handle<JSArray> last_match_info,
+                               FixedArrayBuilder* builder) {
+  ASSERT(subject->IsFlat());
+  ASSERT_EQ(1, pattern->length());
+  uc16 pattern_char = pattern->Get(0);

[fschneider, 2010/03/25 10:26:06]

ASSERT that pattern is a uc16-string?

[Lasse Reichstein, 2010/03/26 11:18:26]

Not necessary. Get is generic and works on both kinds of strings, and always
return uc16.

+  // Treating position before first as initial "previous match position".
+  int match_pos = -1;
+
+  for (;;) {  // Break when search complete.
+    builder->EnsureCapacity(kMaxBuilderEntriesPerRegExpMatch);
+    AssertNoAllocation no_gc;
+    if (subject->IsAsciiRepresentation()) {
+      if (pattern_char > String::kMaxAsciiCharCode) {

[fschneider, 2010/03/25 10:26:06]

No need for multi-line if.

[Lasse Reichstein, 2010/03/26 11:18:26]

How not?

+        break;
+      }
+      Vector<const char> subject_vector = subject->ToAsciiVector();
+      char pattern_ascii_char = static_cast<char>(pattern_char);
+      bool complete = SearchCharMultiple<const char>(subject_vector,
+                                                     *pattern,
+                                                     pattern_ascii_char,
+                                                     builder,
+                                                     &match_pos);
+      if (complete) break;
+    } else {
+      Vector<const uc16> subject_vector = subject->ToUC16Vector();
+      bool complete = SearchCharMultiple<const uc16>(subject_vector,
+                                                     *pattern,
+                                                     pattern_char,
+                                                     builder,
+                                                     &match_pos);
+      if (complete) break;
+    }
+  }
+
+  if (match_pos >= 0) {
+    SetLastMatchInfoNoCaptures(subject,
+                               last_match_info,
+                               match_pos,
+                               match_pos + 1);
+    return true;
+  }
+  return false;  // No matches at all.
+}
+
+
+template <typename schar, typename pchar>
+static bool SearchStringMultiple(Vector<schar> subject,
+                                 String* pattern,
+                                 Vector<pchar> pattern_string,
+                                 FixedArrayBuilder* builder,
+                                 int* match_pos) {
+  int pos = *match_pos;
+  int subject_length = subject.length();
+  int pattern_length = pattern_string.length();
+  int max_search_start = subject_length - pattern_length;
+  bool is_ascii = (sizeof(schar) == 1);
+  StringSearchStrategy strategy =
+      InitializeStringSearch(pattern_string, is_ascii);
+  switch (strategy) {
+    case SEARCH_FAIL: return false;
+    case SEARCH_SHORT: {

[fschneider, 2010/03/25 10:26:06]

No need for { } block?

[Lasse Reichstein, 2010/03/26 11:18:26]

Done.

+      while (pos <= max_search_start) {
+        if (!builder->HasCapacity(kMaxBuilderEntriesPerRegExpMatch)) {
+          *match_pos = pos;
+          return false;
+        }
+        // Position of end of previous match.
+        int match_end = pos + pattern_length;
+        int new_pos = SimpleIndexOf(subject, pattern_string, match_end);
+        if (new_pos >= 0) {

[fschneider, 2010/03/25 10:26:06]

Reverse condition here too?

if (new_pos < 0) break;
...

[Lasse Reichstein, 2010/03/26 11:18:26]

Same argument as last time, I want the "then" branch to be the fast case (the
one that keeps looping).

+          // A match.
+          if (new_pos > match_end) {
+            ReplacementStringBuilder::AddSubjectSlice(builder,
+                                                      match_end,
+                                                      new_pos);
+          }
+          pos = new_pos;
+          builder->Add(pattern);
+        } else {
+          break;
+        }
+      }
+      break;
+    }
+    case SEARCH_LONG: {

[fschneider, 2010/03/25 10:26:06]

No need for { } block?

[Lasse Reichstein, 2010/03/26 11:18:26]

Done.

+      while (pos  <= max_search_start) {
+        if (!builder->HasCapacity(kMaxBuilderEntriesPerRegExpMatch)) {
+         *match_pos = pos;
+         return false;
+        }
+        int new_pos = ComplexIndexOf(subject,
+                                     pattern_string,
+                                     pos + pattern_length);
+        if (new_pos >= 0) {

[fschneider, 2010/03/25 10:26:06]

And here?

if (new_pos < 0) break;
...

[Lasse Reichstein, 2010/03/26 11:18:26]

Also retained.

+         // A match.
+          if (new_pos > pos) {
+           ReplacementStringBuilder::AddSubjectSlice(builder, pos, new_pos);
+          }
+          pos = new_pos;
+          builder->Add(pattern);
+        } else {
+         break;
+        }
+      }
+      break;
+    }
+  }
+  if (pos < max_search_start) {
+    ReplacementStringBuilder::AddSubjectSlice(builder,
+                                              pos + pattern_length,
+                                              subject_length);
+  }
+  *match_pos = pos;
+  return true;
+}
+
+
+static bool SearchStringMultiple(Handle<String> subject,
+                                 Handle<String> pattern,
+                                 Handle<JSArray> last_match_info,
+                                 FixedArrayBuilder* builder) {
+  ASSERT(subject->IsFlat());
+  ASSERT(pattern->IsFlat());
+  ASSERT(pattern->length() > 1);
+
+  // Treating as if a previous match was before first character.
+  int match_pos = -pattern->length();
+
+  for (;;) {  // Break when search complete.
+    builder->EnsureCapacity(kMaxBuilderEntriesPerRegExpMatch);
+    AssertNoAllocation no_gc;
+    if (subject->IsAsciiRepresentation()) {
+      Vector<const char> subject_vector = subject->ToAsciiVector();
+      if (pattern->IsAsciiRepresentation()) {
+        if (SearchStringMultiple(subject_vector,
+                                 *pattern,
+                                 pattern->ToAsciiVector(),
+                                 builder,
+                                 &match_pos)) break;
+      } else {
+        if (SearchStringMultiple(subject_vector,
+                                 *pattern,
+                                 pattern->ToUC16Vector(),
+                                 builder,
+                                 &match_pos)) break;
+      }
+    } else {
+      Vector<const uc16> subject_vector = subject->ToUC16Vector();
+      if (pattern->IsAsciiRepresentation()) {
+        if (SearchStringMultiple(subject_vector,
+                                 *pattern,
+                                 pattern->ToAsciiVector(),
+                                 builder,
+                                 &match_pos)) break;
+      } else {
+        if (SearchStringMultiple(subject_vector,
+                                 *pattern,
+                                 pattern->ToUC16Vector(),
+                                 builder,
+                                 &match_pos)) break;
+      }
+    }
+  }
+
+  if (match_pos >= 0) {
+    SetLastMatchInfoNoCaptures(subject,
+                               last_match_info,
+                               match_pos,
+                               match_pos + pattern->length());
+    return true;
+  }
+  return false;  // No matches at all.
+}
+
+
+static RegExpImpl::IrregexpResult SearchRegExpNoCaptureMultiple(
+    Handle<String> subject,
+    Handle<JSRegExp> regexp,
+    Handle<JSArray> last_match_array,
+    FixedArrayBuilder* builder) {
+  ASSERT(subject->IsFlat());
+  int match_start = -1;
+  int match_end = 0;
+  int pos = 0;
+  int required_registers = RegExpImpl::IrregexpPrepare(regexp, subject);
+  if (required_registers < 0) return RegExpImpl::RE_EXCEPTION;
+
+  OffsetsVector registers(required_registers);
+  Vector<int> register_vector(registers.vector(), registers.length());
+  int subject_length = subject->length();
+
+  for (;;) {  // Break on failure, return on exception.
+    RegExpImpl::IrregexpResult result =
+        RegExpImpl::IrregexpExecOnce(regexp,
+                                     subject,
+                                     pos,
+                                     register_vector);
+    if (result == RegExpImpl::RE_SUCCESS) {
+      match_start = register_vector[0];
+      builder->EnsureCapacity(kMaxBuilderEntriesPerRegExpMatch);
+      if (match_end < match_start) {
+        ReplacementStringBuilder::AddSubjectSlice(builder,
+                                                  match_end,
+                                                  match_start);
+      }
+      match_end = register_vector[1];
+      HandleScope loop_scope;
+      builder->Add(*Factory::NewSubString(subject, match_start, match_end));
+      if (match_start != match_end) {
+        pos = match_end;
+      } else {
+        pos = match_end + 1;
+        if (pos > subject_length) break;
+      }
+    } else if (result == RegExpImpl::RE_FAILURE) {
+      break;
+    } else {
+      ASSERT_EQ(result, RegExpImpl::RE_EXCEPTION);
+      return result;
+    }
+  }
+
+  if (match_start >= 0) {
+    if (match_end < subject_length) {
+      ReplacementStringBuilder::AddSubjectSlice(builder,
+                                                match_end,
+                                                subject_length);
+    }
+    SetLastMatchInfoNoCaptures(subject,
+                               last_match_array,
+                               match_start,
+                               match_end);
+    return RegExpImpl::RE_SUCCESS;
+  } else {
+    return RegExpImpl::RE_FAILURE;  // No matches at all.
+  }
+}
+
+
+static RegExpImpl::IrregexpResult SearchRegExpMultiple(
+    Handle<String> subject,
+    Handle<JSRegExp> regexp,
+    Handle<JSArray> last_match_array,
+    FixedArrayBuilder* builder) {
+
+  ASSERT(subject->IsFlat());
+  int required_registers = RegExpImpl::IrregexpPrepare(regexp, subject);
+  if (required_registers < 0) return RegExpImpl::RE_EXCEPTION;
+
+  OffsetsVector registers(required_registers);
+  Vector<int> register_vector(registers.vector(), registers.length());
+
+  RegExpImpl::IrregexpResult result =
+      RegExpImpl::IrregexpExecOnce(regexp,
+                                   subject,
+                                   0,
+                                   register_vector);
+
+  int capture_count = regexp->CaptureCount();
+  int subject_length = subject->length();
+
+  // Position to search from.
+  int pos = 0;
+  // End of previous match. Differs from pos if match was empty.
+  int match_end = 0;
+  if (result == RegExpImpl::RE_SUCCESS) {
+    // Need to keep a copy of the previous match for creating last_match_info
+    // at the end, so we have two vectors that we swap between.
+    OffsetsVector registers2(required_registers);
+    Vector<int> prev_register_vector(registers2.vector(), registers2.length());
+
+    do {
+      int match_start = register_vector[0];
+      builder->EnsureCapacity(kMaxBuilderEntriesPerRegExpMatch);
+      if (match_end < match_start) {
+        ReplacementStringBuilder::AddSubjectSlice(builder,
+                                                  match_end,
+                                                  match_start);
+      }
+      match_end = register_vector[1];
+
+      {
+        // Avoid accumulating new handles inside loop.
+        HandleScope temp_scope;
+        // Arguments array to replace function is match, captures, index and
+        // subject, i.e., 3 + capture count in total.
+        Handle<FixedArray> elements = Factory::NewFixedArray(3 + capture_count);
+        elements->set(0, *Factory::NewSubString(subject,
+                                                match_start,
+                                                match_end));
+        for (int i = 1; i <= capture_count; i++) {
+          Handle<String> substring =
+              Factory::NewSubString(subject,
+                                    register_vector[i * 2],
+                                    register_vector[i * 2 + 1]);
+          elements->set(i, *substring);
+        }
+        elements->set(capture_count + 1, Smi::FromInt(match_start));
+        elements->set(capture_count + 2, *subject);
+        builder->Add(*Factory::NewJSArrayWithElements(elements));
+      }
+      // Swap register vectors, so the last successful match is in
+      // prev_register_vector.
+      Vector<int> tmp = prev_register_vector;

[fschneider, 2010/03/25 10:26:06]

Could you have one stack-allocated instance of the tmp-Vector and reuse it
instead of constructing a new one for each swap?

[Lasse Reichstein, 2010/03/26 11:18:26]

Vector is a two-value struct. Allocating a single stack-vector won't be faster
than allocating a new each time, it'll be at the same place on the stack anyway.

+      prev_register_vector = register_vector;
+      register_vector = tmp;
+
+      if (match_end > match_start) {
+        pos = match_end;
+      } else {
+        pos = match_end + 1;
+        if (pos > subject_length) {
+          break;
+        }
+      }
+
+      result = RegExpImpl::IrregexpExecOnce(regexp,
+                                            subject,
+                                            pos,
+                                            register_vector);
+    } while (result == RegExpImpl::RE_SUCCESS);
+
+    if (result != RegExpImpl::RE_EXCEPTION) {
+      // Finished matching, with at least one match.
+      if (match_end < subject_length) {
+        ReplacementStringBuilder::AddSubjectSlice(builder,
+                                                  match_end,
+                                                  subject_length);
+      }
+
+      int last_match_capture_count = (capture_count + 1) * 2;
+      int last_match_array_size =
+          last_match_capture_count + RegExpImpl::kLastMatchOverhead;
+      last_match_array->EnsureSize(last_match_array_size);
+      AssertNoAllocation no_gc;
+      FixedArray* elements = FixedArray::cast(last_match_array->elements());
+      RegExpImpl::SetLastCaptureCount(elements, last_match_capture_count);
+      RegExpImpl::SetLastSubject(elements, *subject);
+      RegExpImpl::SetLastInput(elements, *subject);
+      for (int i = 0; i < last_match_capture_count; i++) {
+        RegExpImpl::SetCapture(elements, i, prev_register_vector[i]);
+      }
+      return RegExpImpl::RE_SUCCESS;
+    }
+  }
+  // No matches at all, return failure or exception result directly.
+  return result;
+}
+
+
+static Object* Runtime_RegExpExecMultiple(Arguments args) {
+  ASSERT(args.length() == 4);
+  HandleScope handles;
+
+  CONVERT_ARG_CHECKED(String, subject, 1);
+  if (!subject->IsFlat()) { FlattenString(subject); }
+  CONVERT_ARG_CHECKED(JSRegExp, regexp, 0);
+  CONVERT_ARG_CHECKED(JSArray, last_match_info, 2);
+  CONVERT_ARG_CHECKED(JSArray, result_array, 3);
+
+  ASSERT(last_match_info->HasFastElements());
+  ASSERT(regexp->GetFlags().is_global());
+  Handle<FixedArray> result_elements;
+  if (result_array->HasFastElements()) {
+    result_elements =
+        Handle<FixedArray>(FixedArray::cast(result_array->elements()));
+  } else {
+    result_elements = Factory::NewFixedArrayWithHoles(16);
+  }
+  FixedArrayBuilder builder(result_elements);
+
+  if (regexp->TypeTag() == JSRegExp::ATOM) {
+    Handle<String> pattern(
+        String::cast(regexp->DataAt(JSRegExp::kAtomPatternIndex)));
+    int pattern_length = pattern->length();
+    if (pattern_length == 1) {

[fschneider, 2010/03/25 10:26:06]

Or just:

if (pattern->length() == 1 &&
    SearchCharMultiple(...)) {
  return *builder.ToJSArray(result_array);
}
  

[Lasse Reichstein, 2010/03/26 11:18:26]

That wouldn't return null if SearchCharMultiple returns false.

+      if (SearchCharMultiple(subject, pattern, last_match_info, &builder)) {
+        return *builder.ToJSArray(result_array);
+      }
+      return Heap::null_value();
+    }
+
+    if (!pattern->IsFlat()) FlattenString(pattern);
+    if (SearchStringMultiple(subject, pattern, last_match_info, &builder)) {
+      return *builder.ToJSArray(result_array);
+    }
+    return Heap::null_value();
+  }
+
+  ASSERT_EQ(regexp->TypeTag(), JSRegExp::IRREGEXP);
+
+  int capture_count = regexp->CaptureCount();
+  if (capture_count == 0) {
+    RegExpImpl::IrregexpResult result =
+        SearchRegExpNoCaptureMultiple(subject,
+                                      regexp,
+                                      last_match_info,
+                                      &builder);
+    if (result == RegExpImpl::RE_SUCCESS)  {
+      return *builder.ToJSArray(result_array);
+    }
+    if (result == RegExpImpl::RE_FAILURE) {
+      return Heap::null_value();
+    }
+    ASSERT_EQ(result, RegExpImpl::RE_EXCEPTION);
+    return Failure::Exception();
+  }
+
+  RegExpImpl::IrregexpResult result =
+      SearchRegExpMultiple(subject, regexp, last_match_info, &builder);
+  if (result == RegExpImpl::RE_SUCCESS) return *builder.ToJSArray(result_array);

[fschneider, 2010/03/25 10:26:06]

The test for the result seems duplicated. You could write:

RegExpImpl::IrregexpResult result;
if (capture_count == 0) {
  result = SearchRegExpNoCaptureMultiple(...);
} else {
  result = SearchRegExpMultiple(...)'
}
if (result == RegExpImpl::RE_SUCCESS) return ...
if (result == RegExpImpl::RE_FAILURE) return ...
ASSERT_EQ(result, RegExpImpl::RE_EXCEPTION);
return Failure::Exception();

[Lasse Reichstein, 2010/03/26 11:18:26]

Done.

+  if (result == RegExpImpl::RE_FAILURE) return Heap::null_value();
+  ASSERT_EQ(result, RegExpImpl::RE_EXCEPTION);
+  return Failure::Exception();
+}
+
+
 static Object* Runtime_NumberToRadixString(Arguments args) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 2);
 
   // Fast case where the result is a one character string.
   if (args[0]->IsSmi() && args[1]->IsSmi()) {
     int value = Smi::cast(args[0])->value();
     int radix = Smi::cast(args[1])->value();
     if (value >= 0 && value < radix) {
       RUNTIME_ASSERT(radix <= 36);
@@ skipping 6546 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal