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

src/arm/regexp-macro-assembler-arm.cc

Index: src/arm/regexp-macro-assembler-arm.cc
diff --git a/src/arm/regexp-macro-assembler-arm.cc b/src/arm/regexp-macro-assembler-arm.cc
index 8f45886d92f404a5da28126181a8aaec276c7aa8..5fd6c5370a70e642a2af2547f3b62ec933afca3f 100644
--- a/src/arm/regexp-macro-assembler-arm.cc
+++ b/src/arm/regexp-macro-assembler-arm.cc
@@ -142,7 +142,6 @@ int RegExpMacroAssemblerARM::stack_limit_slack()  {
 
 void RegExpMacroAssemblerARM::AdvanceCurrentPosition(int by) {
   if (by != 0) {
-    Label inside_string;
     __ add(current_input_offset(),
            current_input_offset(), Operand(by * char_size()));
   }
@@ -927,6 +926,19 @@ void RegExpMacroAssemblerARM::ReadStackPointerFromRegister(int reg) {
 }
 
 
+void RegExpMacroAssemblerARM::SetCurrentPositionFromEnd(int by) {
+  NearLabel after_position;
+  __ cmp(current_input_offset(), Operand(by * char_size()));
+  __ b(hs, &after_position);
+  __ mov(current_input_offset(), Operand(by * char_size()));
+  // On RegExp code entry (where this operation is used), the character before
+  // the current position is expected to be already loaded.
+  // We have advenced the position, so it's safe to read backwards.
+  LoadCurrentCharacterUnchecked(-1, 1);
+  __ bind(&after_position);
+}
+
+
 void RegExpMacroAssemblerARM::SetRegister(int register_index, int to) {
   ASSERT(register_index >= num_saved_registers_);  // Reserved for positions!
   __ mov(r0, Operand(to));