Reduce work done in EatsAtLeast to a sane level.

src/jsregexp.cc

 // Copyright 2006-2008 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 1945 matching lines @@
   }
 
   // If we get here code has been generated for this node too many times or
   // recursion is too deep.  Time to switch to a generic version.  The code for
   // generic versions above can handle deep recursion properly.
   bool ok = trace->Flush(compiler, this);
   return ok ? DONE : FAIL;
 }
 
 
-int ActionNode::EatsAtLeast(int recursion_depth) {
+int ActionNode::EatsAtLeast(int still_to_find, int recursion_depth) {
   if (recursion_depth > RegExpCompiler::kMaxRecursion) return 0;
   if (type_ == POSITIVE_SUBMATCH_SUCCESS) return 0;  // Rewinds input!
-  return on_success()->EatsAtLeast(recursion_depth + 1);
+  return on_success()->EatsAtLeast(still_to_find, recursion_depth + 1);
 }
 
 
-int AssertionNode::EatsAtLeast(int recursion_depth) {
+int AssertionNode::EatsAtLeast(int still_to_find, int recursion_depth) {
   if (recursion_depth > RegExpCompiler::kMaxRecursion) return 0;
-  return on_success()->EatsAtLeast(recursion_depth + 1);
+  return on_success()->EatsAtLeast(still_to_find, recursion_depth + 1);
 }
 
 
-int BackReferenceNode::EatsAtLeast(int recursion_depth) {
+int BackReferenceNode::EatsAtLeast(int still_to_find, int recursion_depth) {
   if (recursion_depth > RegExpCompiler::kMaxRecursion) return 0;
-  return on_success()->EatsAtLeast(recursion_depth + 1);
+  return on_success()->EatsAtLeast(still_to_find, recursion_depth + 1);
 }
 
 
-int TextNode::EatsAtLeast(int recursion_depth) {
+int TextNode::EatsAtLeast(int still_to_find, int recursion_depth) {
   int answer = Length();
-  if (answer >= 4) return answer;
+  if (answer >= still_to_find) return answer;
   if (recursion_depth > RegExpCompiler::kMaxRecursion) return answer;
-  return answer + on_success()->EatsAtLeast(recursion_depth + 1);
+  return answer + on_success()->EatsAtLeast(still_to_find - answer,
+                                            recursion_depth + 1);
 }
 
 
-int NegativeLookaheadChoiceNode:: EatsAtLeast(int recursion_depth) {
+int NegativeLookaheadChoiceNode:: EatsAtLeast(int still_to_find, int recursion_depth) {
   if (recursion_depth > RegExpCompiler::kMaxRecursion) return 0;
   // Alternative 0 is the negative lookahead, alternative 1 is what comes
   // afterwards.
   RegExpNode* node = alternatives_->at(1).node();
-  return node->EatsAtLeast(recursion_depth + 1);
+  return node->EatsAtLeast(still_to_find, recursion_depth + 1);
 }
 
 
 void NegativeLookaheadChoiceNode::GetQuickCheckDetails(
     QuickCheckDetails* details,
     RegExpCompiler* compiler,
     int filled_in) {
   // Alternative 0 is the negative lookahead, alternative 1 is what comes
   // afterwards.
   RegExpNode* node = alternatives_->at(1).node();
   return node->GetQuickCheckDetails(details, compiler, filled_in);
 }
 
 
-int ChoiceNode::EatsAtLeastHelper(int recursion_depth,
+int ChoiceNode::EatsAtLeastHelper(int still_to_find,
+                                  int recursion_depth,
                                   RegExpNode* ignore_this_node) {
   if (recursion_depth > RegExpCompiler::kMaxRecursion) return 0;
   int min = 100;
   int choice_count = alternatives_->length();
   for (int i = 0; i < choice_count; i++) {
     RegExpNode* node = alternatives_->at(i).node();
     if (node == ignore_this_node) continue;
-    int node_eats_at_least = node->EatsAtLeast(recursion_depth + 1);
+    int node_eats_at_least = node->EatsAtLeast(still_to_find, recursion_depth + 1);
     if (node_eats_at_least < min) min = node_eats_at_least;
   }
   return min;
 }
 
 
-int LoopChoiceNode::EatsAtLeast(int recursion_depth) {
-  return EatsAtLeastHelper(recursion_depth, loop_node_);
+int LoopChoiceNode::EatsAtLeast(int still_to_find, int recursion_depth) {
+  return EatsAtLeastHelper(still_to_find, recursion_depth, loop_node_);
 }
 
 
-int ChoiceNode::EatsAtLeast(int recursion_depth) {
-  return EatsAtLeastHelper(recursion_depth, NULL);
+int ChoiceNode::EatsAtLeast(int still_to_find, int recursion_depth) {
+  return EatsAtLeastHelper(still_to_find, recursion_depth, NULL);
 }
 
 
 // Takes the left-most 1-bit and smears it out, setting all bits to its right.
 static inline uint32_t SmearBitsRight(uint32_t v) {
   v |= v >> 1;
   v |= v >> 2;
   v |= v >> 4;
   v |= v >> 8;
   v |= v >> 16;
@@ skipping 759 matching lines @@
   }
   ASSERT(trace->stop_node() == NULL);
   if (!trace->is_trivial()) {
     return trace->Flush(compiler, this);
   }
   return ChoiceNode::Emit(compiler, trace);
 }
 
 
 int ChoiceNode::CalculatePreloadCharacters(RegExpCompiler* compiler) {
-  int preload_characters = EatsAtLeast(0);
+  int preload_characters = EatsAtLeast(4, 0);
 #ifdef CAN_READ_UNALIGNED
   bool ascii = compiler->ascii();
   if (ascii) {
     if (preload_characters > 4) preload_characters = 4;
     // We can't preload 3 characters because there is no machine instruction
     // to do that.  We can't just load 4 because we could be reading
     // beyond the end of the string, which could cause a memory fault.
     if (preload_characters == 3) preload_characters = 2;
   } else {
     if (preload_characters > 2) preload_characters = 2;
@@ skipping 1858 matching lines @@
   EmbeddedVector<byte, 1024> codes;
   RegExpMacroAssemblerIrregexp macro_assembler(codes);
   return compiler.Assemble(&macro_assembler,
                            node,
                            data->capture_count,
                            pattern);
 }
 
 
 }}  // namespace v8::internal