A little peephole optimization for the Irregexp bytecode interpreter.

src/regexp-macro-assembler-irregexp.cc

-// Copyright 2008 the V8 project authors. All rights reserved.
+// Copyright 2008-2009 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
 //       with the distribution.
@@ skipping 20 matching lines @@
 #include "regexp-macro-assembler-irregexp.h"
 #include "regexp-macro-assembler-irregexp-inl.h"
 
 
 namespace v8 { namespace internal {
 
 
 RegExpMacroAssemblerIrregexp::RegExpMacroAssemblerIrregexp(Vector<byte> buffer)
     : buffer_(buffer),
       pc_(0),
-      own_buffer_(false) {
+      own_buffer_(false),
+      advance_current_end_(kInvalidPC) {
 }
 
 
 RegExpMacroAssemblerIrregexp::~RegExpMacroAssemblerIrregexp() {
   if (backtrack_.is_linked()) backtrack_.Unuse();
 }
 
 
 RegExpMacroAssemblerIrregexp::IrregexpImplementation
 RegExpMacroAssemblerIrregexp::Implementation() {
   return kBytecodeImplementation;
 }
 
 
 void RegExpMacroAssemblerIrregexp::Bind(Label* l) {
+  advance_current_end_ = kInvalidPC;
   ASSERT(!l->is_bound());
   if (l->is_linked()) {
     int pos = l->pos();
     while (pos != 0) {
       int fixup = pos;
       pos = *reinterpret_cast<int32_t*>(buffer_.start() + fixup);
       *reinterpret_cast<uint32_t*>(buffer_.start() + fixup) = pc_;
     }
   }
   l->bind_to(pc_);
@@ skipping 97 matching lines @@
   Emit(BC_PUSH_CP, 0);
 }
 
 
 void RegExpMacroAssemblerIrregexp::Backtrack() {
   Emit(BC_POP_BT, 0);
 }
 
 
 void RegExpMacroAssemblerIrregexp::GoTo(Label* l) {
-  Emit(BC_GOTO, 0);
-  EmitOrLink(l);
+  if (advance_current_end_ == pc_) {
+    // Combine advance current and goto.
+    pc_ = advance_current_start_;
+    Emit(BC_ADVANCE_CP_AND_GOTO, advance_current_offset_);
+    EmitOrLink(l);
+    advance_current_end_ = kInvalidPC;
+  } else {
+    // Regular goto.
+    Emit(BC_GOTO, 0);
+    EmitOrLink(l);
+  }
 }
 
 
 void RegExpMacroAssemblerIrregexp::PushBacktrack(Label* l) {
   Emit(BC_PUSH_BT, 0);
   EmitOrLink(l);
 }
 
 
 void RegExpMacroAssemblerIrregexp::Succeed() {
   Emit(BC_SUCCEED, 0);
 }
 
 
 void RegExpMacroAssemblerIrregexp::Fail() {
   Emit(BC_FAIL, 0);
 }
 
 
 void RegExpMacroAssemblerIrregexp::AdvanceCurrentPosition(int by) {
   ASSERT(by >= kMinCPOffset);
   ASSERT(by <= kMaxCPOffset);
+  advance_current_start_ = pc_;
+  advance_current_offset_ = by;
   Emit(BC_ADVANCE_CP, by);
+  advance_current_end_ = pc_;
 }
 
 
 void RegExpMacroAssemblerIrregexp::CheckGreedyLoop(
       Label* on_tos_equals_current_position) {
   Emit(BC_CHECK_GREEDY, 0);
   EmitOrLink(on_tos_equals_current_position);
 }
 
 
@@ skipping 258 matching lines @@
   buffer_ = Vector<byte>::New(old_buffer.length() * 2);
   own_buffer_ = true;
   memcpy(buffer_.start(), old_buffer.start(), old_buffer.length());
   if (old_buffer_was_our_own) {
     old_buffer.Dispose();
   }
 }
 
 
 } }  // namespace v8::internal