Use finite-length end-anchored regexps to reduce part of regexp that is searched.

src/jsregexp.cc

Index: src/jsregexp.cc
diff --git a/src/jsregexp.cc b/src/jsregexp.cc
index 82a370f141fecf845cb4bd08ec3fdd390cc1f519..3c5ddfbeb4ffd0ed4dbb3fb53ef9fd5317d5f2ce 100644
--- a/src/jsregexp.cc
+++ b/src/jsregexp.cc
@@ -5180,7 +5180,10 @@ RegExpEngine::CompilationResult RegExpEngine::Compile(RegExpCompileData* data,
                                                     &compiler,
                                                     compiler.accept());
   RegExpNode* node = captured_body;
-  if (!data->tree->IsAnchored()) {
+  bool is_end_anchored = data->tree->IsAnchoredAtEnd();
+  bool is_start_anchored = data->tree->IsAnchoredAtStart();
+  int max_length = data->tree->max_match();
+  if (!is_start_anchored) {
     // Add a .*? at the beginning, outside the body capture, unless
     // this expression is anchored at the beginning.
     RegExpNode* loop_node =
@@ -5236,6 +5239,15 @@ RegExpEngine::CompilationResult RegExpEngine::Compile(RegExpCompileData* data,
   RegExpMacroAssemblerIrregexp macro_assembler(codes);
 #endif  // V8_INTERPRETED_REGEXP
 
+  // Inserted here, instead of in Assembler, because it depends on information
+  // in the AST that isn't replicated in the Node structure.
+  static const int kMaxBacksearchLimit = 1024;
+  if (is_end_anchored &&
+      !is_start_anchored &&
+      max_length < kMaxBacksearchLimit) {
+    macro_assembler.SetCurrentPositionFromEnd(max_length);
+  }
+
   return compiler.Assemble(&macro_assembler,
                            node,
                            data->capture_count,