Port and integrate the irregexp engine from V8

runtime/vm/regexp_assembler.cc

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "vm/regexp_assembler.h"
+
+#include "vm/bit_vector.h"
+#include "vm/compiler.h"
+#include "vm/dart_entry.h"
+#include "vm/flow_graph_builder.h"
+#include "vm/il_printer.h"
+#include "vm/object_store.h"
+#include "vm/regexp.h"
+#include "vm/resolver.h"
+#include "vm/stack_frame.h"
+#include "vm/unibrow-inl.h"
+#include "vm/unicode.h"
+
+#define I isolate()
+
+// Debugging output macros. TAG() is called at the head of each interesting
+// function and prints its name during execution if irregexp tracing is enabled.
+#define TAG() if (FLAG_trace_irregexp) { TAG_(); }
+#define TAG_() \
+  Print(PushArgument( \
+    Bind(new(I) ConstantInstr(String::ZoneHandle(I, String::Concat( \
+        String::Handle(String::New("TAG: ")), \
+        String::Handle(String::New(__FUNCTION__)), Heap::kOld))))));
+
+#define PRINT(arg) if (FLAG_trace_irregexp) { Print(arg); }
+
+namespace dart {
+
+DEFINE_FLAG(bool, trace_irregexp, false, "Trace irregexps");
+
+static const intptr_t kInvalidTryIndex = -1;
+static const intptr_t kNoTokenPos = -1;
+
+/*
+ * This assembler uses the following main local variables:
+ * - stack_: A pointer to a growable list which we use as an all-purpose stack
+ *           storing backtracking offsets, positions & stored register values.
+ * - current_character_: Stores the currently loaded characters (possibly more
+ *                       than one).
+ * - current_position_: The current position within the string, stored as a
+ *                      negative offset from the end of the string (i.e. the
+ *                      position corresponding to str[0] is -str.length).
+ *                      Note that current_position_ is *not* byte-based, unlike
+ *                      original V8 code.
+ *
+ * Results are returned though an array of capture indices, stored at
+ * matches_param_. A null array specifies a failure to match. The match indices
+ * [start_inclusive, end_exclusive] for capture group i are stored at positions
+ * matches_param_[i * 2] and matches_param_[i * 2 + 1], respectively. Match
+ * indices of -1 denote non-matched groups. Note that we store these indices
+ * as a negative offset from the end of the string in position_registers_
+ * during processing, and convert them to standard indexes when copying them
+ * to matches_param_ on successful match.
+ */
+
+RegExpMacroAssembler::RegExpMacroAssembler(Isolate* isolate)
+  : slow_safe_compiler_(false),
+    global_mode_(NOT_GLOBAL),
+    isolate_(isolate) {
+}
+
+
+RegExpMacroAssembler::~RegExpMacroAssembler() {
+}
+
+
+IRRegExpMacroAssembler::IRRegExpMacroAssembler(
+    intptr_t specialization_cid,
+    intptr_t capture_count,
+    const ParsedFunction* parsed_function,
+    const ZoneGrowableArray<const ICData*>& ic_data_array,
+    Isolate* isolate)
+    : RegExpMacroAssembler(isolate),
+      specialization_cid_(specialization_cid),
+      parsed_function_(parsed_function),
+      ic_data_array_(ic_data_array),
+      current_instruction_(NULL),
+      stack_(NULL),
+      current_character_(NULL),
+      current_position_(NULL),
+      string_param_(NULL),
+      string_param_length_(NULL),
+      start_index_param_(NULL),
+      position_registers_count_((capture_count + 1) * 2),
+      stack_array_(GrowableObjectArray::ZoneHandle(
+                       isolate, GrowableObjectArray::New(16, Heap::kOld))) {
+  switch (specialization_cid) {
+    case kOneByteStringCid:
+    case kExternalOneByteStringCid: mode_ = ASCII; break;
+    case kTwoByteStringCid:
+    case kExternalTwoByteStringCid: mode_ = UC16; break;
+    default: UNREACHABLE();
+  }
+
+  InitializeLocals();
+
+  // Create and generate all preset blocks.
+  entry_block_ =
+      new(isolate) GraphEntryInstr(
+        parsed_function_,
+        new(isolate) TargetEntryInstr(block_id_.Alloc(), kInvalidTryIndex),
+        Isolate::kNoDeoptId);
+  start_block_ =
+      new(isolate) JoinEntryInstr(block_id_.Alloc(), kInvalidTryIndex);
+  success_block_ =
+      new(isolate) JoinEntryInstr(block_id_.Alloc(), kInvalidTryIndex);
+  backtrack_block_ =
+      new(isolate) JoinEntryInstr(block_id_.Alloc(), kInvalidTryIndex);
+  exit_block_ =
+      new(isolate) JoinEntryInstr(block_id_.Alloc(), kInvalidTryIndex);
+
+  GenerateEntryBlock();
+  GenerateSuccessBlock();
+  GenerateBacktrackBlock();
+  GenerateExitBlock();
+
+  blocks_.Add(entry_block_);
+  blocks_.Add(entry_block_->normal_entry());
+  blocks_.Add(start_block_);
+  blocks_.Add(success_block_);
+  blocks_.Add(backtrack_block_);
+  blocks_.Add(exit_block_);
+
+  // Begin emission at the start_block_.
+  set_current_instruction(start_block_);
+}
+
+
+IRRegExpMacroAssembler::~IRRegExpMacroAssembler() { }
+
+
+void IRRegExpMacroAssembler::InitializeLocals() {
+  // Create local variables and parameters.
+  stack_ = Local(Symbols::stack_());
+  current_character_ = Local(Symbols::current_character_());
+  current_position_ = Local(Symbols::current_position_());
+  string_param_length_ = Local(Symbols::string_param_length_());
+  capture_length_ = Local(Symbols::capture_length_());
+  match_start_index_ = Local(Symbols::match_start_index_());
+  capture_start_index_ = Local(Symbols::capture_start_index_());
+  match_end_index_ = Local(Symbols::match_end_index_());
+  char_in_capture_ = Local(Symbols::char_in_capture_());
+  char_in_match_ = Local(Symbols::char_in_match_());
+  result_ = Local(Symbols::result_());
+
+  string_param_ = Parameter(Symbols::string_param_(), 0);
+  start_index_param_ = Parameter(Symbols::start_index_param_(), 1);
+
+  // Reserve space for all captured group positions. Note that more might
+  // be created on the fly for internal use.
+  for (intptr_t i = 0; i < position_registers_count_; i++) {
+    position_register(i);
+  }
+}
+
+
+void IRRegExpMacroAssembler::GenerateEntryBlock() {
+  set_current_instruction(entry_block_->normal_entry());
+  TAG();
+
+  // Generate a local list variable which we will use as a backtracking stack.
+
+  StoreLocal(stack_, Bind(new(I) ConstantInstr(stack_array_)));
+  Do(InstanceCall(InstanceCallDescriptor(Symbols::clear()), PushLocal(stack_)));
+
+  // Store string.length.
+  PushArgumentInstr* string_push = PushLocal(string_param_);
+
+  StoreLocal(string_param_length_,
+             Bind(InstanceCall(InstanceCallDescriptor(
+                                 String::ZoneHandle(
+                                   Field::GetterSymbol(Symbols::Length()))),
+                               string_push)));
+
+  // Initialize all capture registers.
+  ClearRegisters(0, position_registers_count_ - 1);
+
+  // Store (start_index - string.length) as the current position (since it's a
+  // negative offset from the end of the string).
+  PushArgumentInstr* start_index_push = PushLocal(start_index_param_);
+  PushArgumentInstr* length_push = PushLocal(string_param_length_);
+
+  StoreLocal(current_position_, Bind(Sub(start_index_push, length_push)));
+
+  // Jump to the start block.
+  current_instruction_->Goto(start_block_);
+}
+
+
+void IRRegExpMacroAssembler::GenerateBacktrackBlock() {
+  set_current_instruction(backtrack_block_);
+  TAG();
+  Backtrack();
+}
+
+
+void IRRegExpMacroAssembler::GenerateSuccessBlock() {
+  set_current_instruction(success_block_);
+  TAG();
+
+  Definition* type_args_null_def = new(I) ConstantInstr(
+        TypeArguments::ZoneHandle(I, TypeArguments::null()));
+  PushArgumentInstr* type_arg_push = PushArgument(Bind(type_args_null_def));
+  PushArgumentInstr* length_push =
+      PushArgument(Bind(Uint64Constant(position_registers_count_)));
+
+  const Library& lib = Library::Handle(Library::CoreLibrary());
+  const Class& list_class = Class::Handle(
+        lib.LookupCoreClass(Symbols::List()));
+  const Function& list_ctor =
+      Function::ZoneHandle(I, list_class.LookupFactory(Symbols::ListFactory()));
+
+  // TODO(jgruber): Use CreateArrayInstr and StoreIndexed instead.
+  StoreLocal(result_, Bind(StaticCall(list_ctor, type_arg_push, length_push)));
+
+  // Store captured offsets in the `matches` parameter.
+  // TODO(jgruber): Eliminate position_register locals and access `matches`
+  // directly.
+  for (intptr_t i = 0; i < position_registers_count_; i++) {
+    PushArgumentInstr* matches_push = PushLocal(result_);
+    PushArgumentInstr* index_push = PushArgument(Bind(Uint64Constant(i)));
+
+    // Convert negative offsets from the end of the string to string indices.
+    PushArgumentInstr* offset_push = PushLocal(position_register(i));
+    PushArgumentInstr* len_push = PushLocal(string_param_length_);
+    PushArgumentInstr* value_push =
+        PushArgument(Bind(Add(offset_push, len_push)));
+
+    Do(InstanceCall(InstanceCallDescriptor::FromToken(Token::kASSIGN_INDEX),
+                    matches_push,
+                    index_push,
+                    value_push));
+  }
+
+  // Print the result if tracing.
+  PRINT(PushLocal(result_));
+
+  // Return true on success.
+  AppendInstruction(new(I) ReturnInstr(kNoTokenPos, Bind(LoadLocal(result_))));
+}
+
+
+void IRRegExpMacroAssembler::GenerateExitBlock() {
+  set_current_instruction(exit_block_);
+  TAG();
+
+  // Return false on failure.
+  AppendInstruction(new(I) ReturnInstr(kNoTokenPos, Bind(LoadLocal(result_))));
+}
+
+
+#if defined(TARGET_ARCH_ARM64) ||                                              \
+    defined(TARGET_ARCH_ARM) ||                                                \
+    defined(TARGET_ARCH_MIPS)
+// Disabling unaligned accesses forces the regexp engine to load characters one
+// by one instead of up to 4 at once, along with the associated performance hit.
+// TODO(jgruber): Be less conservative about disabling unaligned accesses.
+// For instance, ARMv6 supports unaligned accesses. Once it is enabled here,
+// update LoadCodeUnitsInstr methods for the appropriate architectures.
+static const bool kEnableUnalignedAccesses = false;
+#else
+static const bool kEnableUnalignedAccesses = true;
+#endif
+bool IRRegExpMacroAssembler::CanReadUnaligned() {
+  return kEnableUnalignedAccesses && !slow_safe();
+}
+
+
+RawArray* IRRegExpMacroAssembler::Execute(
+    const Function& function,
+    const String& input,
+    const Smi& start_offset,
+    Isolate* isolate) {
+  // Create the argument list.
+  const Array& args = Array::Handle(Array::New(2));
+  args.SetAt(0, input);
+  args.SetAt(1, start_offset);
+
+  // And finally call the generated code.
+
+  const Object& retval =
+      Object::Handle(isolate, DartEntry::InvokeFunction(function, args));
+  if (retval.IsError()) {
+    const Error& error = Error::Cast(retval);
+    OS::Print("%s\n", error.ToErrorCString());
+    // Should never happen.
+    UNREACHABLE();
+  }
+
+  if (retval.IsNull()) {
+    return Array::null();
+  }
+
+  ASSERT(retval.IsArray());
+  return Array::Cast(retval).raw();
+}
+
+
+RawBool* IRRegExpMacroAssembler::CaseInsensitiveCompareUC16(
+    RawString* str_raw,
+    RawSmi* lhs_index_raw,
+    RawSmi* rhs_index_raw,
+    RawSmi* length_raw) {
+  const String& str = String::Handle(str_raw);
+  const Smi& lhs_index = Smi::Handle(lhs_index_raw);
+  const Smi& rhs_index = Smi::Handle(rhs_index_raw);
+  const Smi& length = Smi::Handle(length_raw);
+
+  // TODO(jgruber): Optimize as single instance. V8 has this as an
+  // isolate member.
+  unibrow::Mapping<unibrow::Ecma262Canonicalize> canonicalize;
+
+  for (intptr_t i = 0; i < length.Value(); i++) {
+    int32_t c1 = str.CharAt(lhs_index.Value() + i);
+    int32_t c2 = str.CharAt(rhs_index.Value() + i);
+    if (c1 != c2) {
+      int32_t s1[1] = { c1 };
+      canonicalize.get(c1, '\0', s1);
+      if (s1[0] != c2) {
+        int32_t s2[1] = { c2 };
+        canonicalize.get(c2, '\0', s2);
+        if (s1[0] != s2[0]) {
+          return Bool::False().raw();
+        }
+      }
+    }
+  }
+  return Bool::True().raw();
+}
+
+
+LocalVariable* IRRegExpMacroAssembler::Parameter(const String& name,
+                                                 intptr_t index) const {
+  const Type& local_type = Type::ZoneHandle(I, Type::DynamicType());
+  LocalVariable* local =
+      new(I) LocalVariable(kNoTokenPos, name, local_type);
+
+  intptr_t param_frame_index = kParamEndSlotFromFp + kParamCount - index;
+  local->set_index(param_frame_index);
+
+  return local;
+}
+
+
+LocalVariable* IRRegExpMacroAssembler::Local(const String& name) {
+  const Type& local_type = Type::ZoneHandle(I, Type::DynamicType());
+  LocalVariable* local =
+      new(I) LocalVariable(kNoTokenPos, name, local_type);
+  local->set_index(GetNextLocalIndex());
+
+  return local;
+}
+
+
+ConstantInstr* IRRegExpMacroAssembler::Int64Constant(int64_t value) const {
+  return new(I) ConstantInstr(
+        Integer::ZoneHandle(I, Integer::New(value, Heap::kOld)));
+}
+
+
+ConstantInstr* IRRegExpMacroAssembler::Uint64Constant(uint64_t value) const {
+  return new(I) ConstantInstr(
+        Integer::ZoneHandle(I, Integer::NewFromUint64(value, Heap::kOld)));
+}
+
+
+ConstantInstr* IRRegExpMacroAssembler::BoolConstant(bool value) const {
+  return new(I) ConstantInstr(value ? Bool::True() : Bool::False());
+}
+
+
+ConstantInstr* IRRegExpMacroAssembler::StringConstant(const char* value) const {
+  return new(I) ConstantInstr(
+        String::ZoneHandle(I, String::New(value, Heap::kOld)));
+}
+
+
+ConstantInstr* IRRegExpMacroAssembler::WordCharacterMapConstant() const {
+  const Library& lib = Library::Handle(I, Library::CoreLibrary());
+  const Class& regexp_class = Class::Handle(I,
+        lib.LookupClassAllowPrivate(Symbols::JSSyntaxRegExp()));
+  const Field& word_character_field = Field::ZoneHandle(I,
+      regexp_class.LookupStaticField(Symbols::_wordCharacterMap()));
+  ASSERT(!word_character_field.IsNull());
+
+  if (word_character_field.IsUninitialized()) {
+    word_character_field.EvaluateInitializer();
+  }
+  ASSERT(!word_character_field.IsUninitialized());
+
+  return new(I) ConstantInstr(
+        Instance::ZoneHandle(I, word_character_field.value()));
+}
+
+
+ComparisonInstr* IRRegExpMacroAssembler::Comparison(
+    ComparisonKind kind, Definition* lhs, Definition* rhs) {
+  Token::Kind strict_comparison = Token::kEQ_STRICT;
+  Token::Kind intermediate_operator = Token::kILLEGAL;
+  switch (kind) {
+  case kEQ:
+    intermediate_operator = Token::kEQ;
+    break;
+  case kNE:
+    intermediate_operator = Token::kEQ;
+    strict_comparison = Token::kNE_STRICT;
+    break;
+  case kLT:
+    intermediate_operator = Token::kLT;
+    break;
+  case kGT:
+    intermediate_operator = Token::kGT;
+    break;
+  case kLTE:
+    intermediate_operator = Token::kLTE;
+    break;
+  case kGTE:
+    intermediate_operator = Token::kGTE;
+    break;
+  default:
+    UNREACHABLE();
+  }
+
+  ASSERT(intermediate_operator != Token::kILLEGAL);
+
+  PushArgumentInstr* lhs_push = PushArgument(Bind(lhs));
+  PushArgumentInstr* rhs_push = PushArgument(Bind(rhs));
+
+  Value* lhs_value =
+      Bind(InstanceCall(
+             InstanceCallDescriptor::FromToken(intermediate_operator),
+             lhs_push,
+             rhs_push));
+  Value* rhs_value = Bind(BoolConstant(true));
+
+  return new(I) StrictCompareInstr(kNoTokenPos, strict_comparison,
+                                   lhs_value, rhs_value, true);
+}
+
+
+StaticCallInstr* IRRegExpMacroAssembler::StaticCall(
+    const Function& function) const {
+  ZoneGrowableArray<PushArgumentInstr*>* arguments =
+      new(I) ZoneGrowableArray<PushArgumentInstr*>(0);
+  return StaticCall(function, arguments);
+}
+
+
+StaticCallInstr* IRRegExpMacroAssembler::StaticCall(
+    const Function& function,
+    PushArgumentInstr* arg1) const {
+  ZoneGrowableArray<PushArgumentInstr*>* arguments =
+      new(I) ZoneGrowableArray<PushArgumentInstr*>(1);
+  arguments->Add(arg1);
+
+  return StaticCall(function, arguments);
+}
+
+
+StaticCallInstr* IRRegExpMacroAssembler::StaticCall(
+    const Function& function,
+    PushArgumentInstr* arg1,
+    PushArgumentInstr* arg2) const {
+  ZoneGrowableArray<PushArgumentInstr*>* arguments =
+      new(I) ZoneGrowableArray<PushArgumentInstr*>(2);
+  arguments->Add(arg1);
+  arguments->Add(arg2);
+
+  return StaticCall(function, arguments);
+}
+
+
+StaticCallInstr* IRRegExpMacroAssembler::StaticCall(
+    const Function& function,
+    ZoneGrowableArray<PushArgumentInstr*>* arguments) const {
+  return new(I) StaticCallInstr(kNoTokenPos,
+                                function,
+                                Object::null_array(),
+                                arguments,
+                                ic_data_array_);
+}
+
+
+InstanceCallInstr* IRRegExpMacroAssembler::InstanceCall(
+    const InstanceCallDescriptor& desc,
+    PushArgumentInstr* arg1) const {
+  ZoneGrowableArray<PushArgumentInstr*>* arguments =
+      new(I) ZoneGrowableArray<PushArgumentInstr*>(1);
+  arguments->Add(arg1);
+
+  return InstanceCall(desc, arguments);
+}
+
+
+InstanceCallInstr* IRRegExpMacroAssembler::InstanceCall(
+    const InstanceCallDescriptor& desc,
+    PushArgumentInstr* arg1,
+    PushArgumentInstr* arg2) const {
+  ZoneGrowableArray<PushArgumentInstr*>* arguments =
+      new(I) ZoneGrowableArray<PushArgumentInstr*>(2);
+  arguments->Add(arg1);
+  arguments->Add(arg2);
+
+  return InstanceCall(desc, arguments);
+}
+
+
+InstanceCallInstr* IRRegExpMacroAssembler::InstanceCall(
+    const InstanceCallDescriptor& desc,
+    PushArgumentInstr* arg1,
+    PushArgumentInstr* arg2,
+    PushArgumentInstr* arg3) const {
+  ZoneGrowableArray<PushArgumentInstr*>* arguments =
+      new(I) ZoneGrowableArray<PushArgumentInstr*>(3);
+  arguments->Add(arg1);
+  arguments->Add(arg2);
+  arguments->Add(arg3);
+
+  return InstanceCall(desc, arguments);
+}
+
+
+InstanceCallInstr* IRRegExpMacroAssembler::InstanceCall(
+    const InstanceCallDescriptor& desc,
+    ZoneGrowableArray<PushArgumentInstr*> *arguments) const {
+  return
+    new(I) InstanceCallInstr(kNoTokenPos,
+                             desc.name,
+                             desc.token_kind,
+                             arguments,
+                             Object::null_array(),
+                             desc.checked_argument_count,
+                             ic_data_array_);
+}
+
+
+LoadLocalInstr* IRRegExpMacroAssembler::LoadLocal(LocalVariable* local) const {
+  return new(I) LoadLocalInstr(*local);
+}
+
+
+void IRRegExpMacroAssembler::StoreLocal(LocalVariable* local,
+                                        Value* value) {
+  Do(new(I) StoreLocalInstr(*local, value));
+}
+
+
+void IRRegExpMacroAssembler::set_current_instruction(Instruction* instruction) {
+  current_instruction_ = instruction;
+}
+
+
+Value* IRRegExpMacroAssembler::Bind(Definition* definition) {
+  AppendInstruction(definition);
+  definition->set_temp_index(temp_id_.Alloc());
+
+  return new(I) Value(definition);
+}
+
+
+void IRRegExpMacroAssembler::Do(Definition* definition) {
+  AppendInstruction(definition);
+}
+
+// In some cases, the V8 irregexp engine generates unreachable code by emitting
+// a jmp not followed by a bind. We cannot do the same, since it is impossible
+// to append to a block following a jmp. In such cases, assume that we are doing
+// the correct thing, but output a warning when tracing.
+#define HANDLE_DEAD_CODE_EMISSION() \
+  if (current_instruction_ == NULL) { \
+    if (FLAG_trace_irregexp) { \
+      OS::Print("WARNING: Attempting to append to a closed assembler. " \
+                "This could be either a bug or generation of dead code " \
+                "inherited from V8.\n"); \
+    } \
+    BlockLabel dummy; \
+    BindBlock(&dummy); \
+  }
+
+void IRRegExpMacroAssembler::AppendInstruction(Instruction* instruction) {
+  HANDLE_DEAD_CODE_EMISSION();
+
+  ASSERT(current_instruction_ != NULL);
+  ASSERT(current_instruction_->next() == NULL);
+
+  temp_id_.Dealloc(instruction->InputCount());
+  arg_id_.Dealloc(instruction->ArgumentCount());
+
+  current_instruction_->LinkTo(instruction);
+  set_current_instruction(instruction);
+}
+
+
+void IRRegExpMacroAssembler::CloseBlockWith(Instruction* instruction) {
+  HANDLE_DEAD_CODE_EMISSION();
+
+  ASSERT(current_instruction_ != NULL);
+  ASSERT(current_instruction_->next() == NULL);
+
+  temp_id_.Dealloc(instruction->InputCount());
+  arg_id_.Dealloc(instruction->ArgumentCount());
+
+  current_instruction_->LinkTo(instruction);
+  set_current_instruction(NULL);
+}
+
+
+void IRRegExpMacroAssembler::GoTo(BlockLabel* to) {
+  if (to == NULL) {
+    Backtrack();
+  } else {
+    to->SetLinked();
+    GoTo(to->block());
+  }
+}
+
+
+// Closes the current block with a goto, and unsets current_instruction_.
+// BindBlock() must be called before emission can continue.
+void IRRegExpMacroAssembler::GoTo(JoinEntryInstr* to) {
+  HANDLE_DEAD_CODE_EMISSION();
+
+  ASSERT(current_instruction_ != NULL);
+  ASSERT(current_instruction_->next() == NULL);
+  current_instruction_->Goto(to);
+  set_current_instruction(NULL);
+}
+
+
+PushArgumentInstr* IRRegExpMacroAssembler::PushArgument(Value* value) {
+  arg_id_.Alloc();
+  PushArgumentInstr* push = new(I) PushArgumentInstr(value);
+  // Do *not* use Do() for push argument instructions.
+  AppendInstruction(push);
+  return push;
+}
+
+
+PushArgumentInstr* IRRegExpMacroAssembler::PushLocal(LocalVariable* local) {
+  return PushArgument(Bind(LoadLocal(local)));
+}
+
+
+void IRRegExpMacroAssembler::Print(const char* str) {
+  Print(PushArgument(
+    Bind(new(I) ConstantInstr(
+           String::ZoneHandle(I, String::New(str, Heap::kOld))))));
+}
+
+
+void IRRegExpMacroAssembler::Print(PushArgumentInstr* argument) {
+  const Library& lib = Library::Handle(Library::CoreLibrary());
+  const Function& print_fn = Function::ZoneHandle(
+        I, lib.LookupFunctionAllowPrivate(Symbols::print()));
+  Do(StaticCall(print_fn, argument));
+}
+
+
+void IRRegExpMacroAssembler::PrintBlocks() {
+  for (intptr_t i = 0; i < blocks_.length(); i++) {
+    FlowGraphPrinter::PrintBlock(blocks_[i], false);
+  }
+}
+
+
+intptr_t IRRegExpMacroAssembler::stack_limit_slack()  {
+  return 32;
+}
+
+
+void IRRegExpMacroAssembler::AdvanceCurrentPosition(intptr_t by) {
+  TAG();
+  if (by != 0) {
+    PushArgumentInstr* cur_pos_push = PushLocal(current_position_);
+    PushArgumentInstr* by_push = PushArgument(Bind(Int64Constant(by)));
+
+    Value* new_pos_value = Bind(Add(cur_pos_push, by_push));
+    StoreLocal(current_position_, new_pos_value);
+  }
+}
+
+
+void IRRegExpMacroAssembler::AdvanceRegister(intptr_t reg, intptr_t by) {
+  TAG();
+  ASSERT(reg >= 0);
+  ASSERT(reg < position_registers_.length());
+
+  if (by != 0) {
+    PushArgumentInstr* reg_push = PushLocal(position_register(reg));
+    PushArgumentInstr* by_push = PushArgument(Bind(Int64Constant(by)));
+    StoreLocal(position_register(reg), Bind(Add(reg_push, by_push)));
+  }
+}
+
+
+void IRRegExpMacroAssembler::Backtrack() {
+  TAG();
+  CheckPreemption();
+
+  GrowableObjectArray& offsets = GrowableObjectArray::ZoneHandle(
+        I, GrowableObjectArray::New(Heap::kOld));
+
+  PushArgumentInstr* block_offsets_push =
+      PushArgument(Bind(new(I) ConstantInstr(offsets)));
+  PushArgumentInstr* block_id_push = PushArgument(PopStack());
+
+  Value* offset_value =
+      Bind(InstanceCall(InstanceCallDescriptor::FromToken(Token::kINDEX),
+                        block_offsets_push,
+                        block_id_push));
+
+  IndirectGotoInstr* igoto = new(I) IndirectGotoInstr(&offsets, offset_value);
+  CloseBlockWith(igoto);
+  igotos_.Add(igoto);
+}
+
+
+// A BindBlock is analogous to assigning a label to a basic block.
+// If the BlockLabel does not yet contain a block, it is created.
+// If there is a current instruction, append a goto to the bound block.
+void IRRegExpMacroAssembler::BindBlock(BlockLabel* label) {
+  ASSERT(!label->IsBound());
+  ASSERT(label->block()->next() == NULL);
+
+  label->SetBound(block_id_.Alloc());
+  blocks_.Add(label->block());
+
+  if (current_instruction_ != NULL) {
+    GoTo(label);
+  }
+  set_current_instruction(label->block());
+
+  // Print the id of the current block if tracing.
+  PRINT(PushArgument(Bind(Uint64Constant(label->block()->block_id()))));
+}
+
+
+intptr_t IRRegExpMacroAssembler::GetNextLocalIndex() {
+  intptr_t id = local_id_.Alloc();
+  return kFirstLocalSlotFromFp - id;
+}
+
+
+LocalVariable* IRRegExpMacroAssembler::position_register(intptr_t index) {
+  // Create position registers as needed.
+  for (intptr_t i = position_registers_.length(); i < index + 1; i++) {
+    position_registers_.Add(Local(Symbols::position_registers_()));
+  }
+
+  return position_registers_[index];
+}
+
+
+// TODO(jgruber): Move the offset table outside to avoid having to keep
+// the assembler around until after code generation; both function or regexp
+// would work.
+void IRRegExpMacroAssembler::FinalizeBlockOffsetTable() {
+  for (intptr_t i = 0; i < igotos_.length(); i++) {
+    IndirectGotoInstr* igoto = igotos_[i];
+    igoto->SetOffsetCount(I, indirect_id_.Count());
+
+    for (intptr_t j = 0; j < igoto->SuccessorCount(); j++) {
+      TargetEntryInstr* target = igoto->SuccessorAt(j);
+
+      // Optimizations might have modified the immediate target block, but
+      // it must end with a goto to the indirect entry.
+      Instruction* instr = target;
+      while (instr != NULL && !instr->IsGoto()) {
+        instr = instr->next();
+      }
+      ASSERT(instr->IsGoto());
+
+      IndirectEntryInstr* ientry =
+          instr->AsGoto()->successor()->AsIndirectEntry();
+      ASSERT(ientry != NULL);
+
+      // The intermediate block was possibly compacted, check both it and the
+      // final indirect entry for a valid offset. If neither are valid, then
+      // the indirect entry is unreachable.
+      intptr_t offset =
+          (target->offset() > 0) ? target->offset() : ientry->offset();
+      if (offset > 0) {
+        intptr_t adjusted_offset =
+            offset - Assembler::EntryPointToPcMarkerOffset();
+        igoto->SetOffsetAt(I, ientry->indirect_id(), adjusted_offset);
+      }
+    }
+  }
+}
+
+void IRRegExpMacroAssembler::FinalizeIndirectGotos() {
+  for (intptr_t i = 0; i < igotos_.length(); i++) {
+    for (intptr_t j = 0; j < entry_block_->indirect_entries().length(); j++) {
+      igotos_.At(i)->AddSuccessor(
+            TargetWithJoinGoto(entry_block_->indirect_entries().At(j)));
+    }
+  }
+}
+
+
+void IRRegExpMacroAssembler::CheckCharacter(uint32_t c, BlockLabel* on_equal) {
+  TAG();
+  Definition* cur_char_def = LoadLocal(current_character_);
+  Definition* char_def = Uint64Constant(c);
+
+  BranchOrBacktrack(Comparison(kEQ, cur_char_def, char_def),
+                    on_equal);
+}
+
+
+void IRRegExpMacroAssembler::CheckCharacterGT(uint16_t limit,
+                                              BlockLabel* on_greater) {
+  TAG();
+  BranchOrBacktrack(Comparison(kGT,
+                               LoadLocal(current_character_),
+                               Uint64Constant(limit)),
+                    on_greater);
+}
+
+
+void IRRegExpMacroAssembler::CheckAtStart(BlockLabel* on_at_start) {
+  TAG();
+
+  BlockLabel not_at_start;
+
+  // Did we start the match at the start of the string at all?
+  BranchOrBacktrack(Comparison(kNE,
+                               LoadLocal(start_index_param_),
+                               Uint64Constant(0)),
+                    &not_at_start);
+
+  // If we did, are we still at the start of the input, i.e. is
+  // (offset == string_length * -1)?
+  Definition* neg_len_def =
+      InstanceCall(InstanceCallDescriptor::FromToken(Token::kNEGATE),
+                   PushLocal(string_param_length_));
+  Definition* offset_def = LoadLocal(current_position_);
+  BranchOrBacktrack(Comparison(kEQ, neg_len_def, offset_def),
+                    on_at_start);
+
+  BindBlock(&not_at_start);
+}
+
+
+void IRRegExpMacroAssembler::CheckNotAtStart(BlockLabel* on_not_at_start) {
+  TAG();
+
+  // Did we start the match at the start of the string at all?
+  BranchOrBacktrack(Comparison(kNE,
+                               LoadLocal(start_index_param_),
+                               Uint64Constant(0)),
+                    on_not_at_start);
+
+  // If we did, are we still at the start of the input, i.e. is
+  // (offset == string_length * -1)?
+  Definition* neg_len_def =
+      InstanceCall(InstanceCallDescriptor::FromToken(Token::kNEGATE),
+                   PushLocal(string_param_length_));
+  Definition* offset_def = LoadLocal(current_position_);
+  BranchOrBacktrack(Comparison(kNE, neg_len_def, offset_def),
+                    on_not_at_start);
+}
+
+
+void IRRegExpMacroAssembler::CheckCharacterLT(uint16_t limit,
+                                              BlockLabel* on_less) {
+  TAG();
+  BranchOrBacktrack(Comparison(kLT,
+                               LoadLocal(current_character_),
+                               Uint64Constant(limit)),
+                    on_less);
+}
+
+
+void IRRegExpMacroAssembler::CheckGreedyLoop(BlockLabel* on_equal) {
+  TAG();
+
+  BlockLabel fallthrough;
+
+  PushArgumentInstr* stack_push = PushLocal(stack_);
+  Definition* stack_tip_def = InstanceCall(
+        InstanceCallDescriptor(String::ZoneHandle(
+                                 I, Field::GetterSymbol(Symbols::last()))),
+        stack_push);
+  Definition* cur_pos_def = LoadLocal(current_position_);
+
+  BranchOrBacktrack(Comparison(kNE, stack_tip_def, cur_pos_def),
+                    &fallthrough);
+
+  // Pop, throwing away the value.
+  stack_push = PushLocal(stack_);
+  Do(InstanceCall(InstanceCallDescriptor(Symbols::removeLast()),
+                  stack_push));
+
+  BranchOrBacktrack(NULL, on_equal);
+
+  BindBlock(&fallthrough);
+}
+
+
+void IRRegExpMacroAssembler::CheckNotBackReferenceIgnoreCase(
+    intptr_t start_reg,
+    BlockLabel* on_no_match) {
+  TAG();
+  ASSERT(start_reg + 1 <= position_registers_.length());
+
+  BlockLabel fallthrough;
+
+  PushArgumentInstr* end_push = PushLocal(position_register(start_reg + 1));
+  PushArgumentInstr* start_push = PushLocal(position_register(start_reg));
+  StoreLocal(capture_length_, Bind(Sub(end_push, start_push)));
+
+  // The length of a capture should not be negative. This can only happen
+  // if the end of the capture is unrecorded, or at a point earlier than
+  // the start of the capture.
+  // BranchOrBacktrack(less, on_no_match);
+
+  BranchOrBacktrack(Comparison(kLT,
+                               LoadLocal(capture_length_),
+                               Uint64Constant(0)),
+                    on_no_match);
+
+  // If length is zero, either the capture is empty or it is completely
+  // uncaptured. In either case succeed immediately.
+  BranchOrBacktrack(Comparison(kEQ,
+                               LoadLocal(capture_length_),
+                               Uint64Constant(0)),
+                    &fallthrough);
+
+
+  // Check that there are sufficient characters left in the input.
+  PushArgumentInstr* pos_push = PushLocal(current_position_);
+  PushArgumentInstr* len_push = PushLocal(capture_length_);
+  BranchOrBacktrack(
+        Comparison(kGT,
+                   InstanceCall(InstanceCallDescriptor::FromToken(Token::kADD),
+                                pos_push,
+                                len_push),
+                   Uint64Constant(0)),
+        on_no_match);
+
+  pos_push = PushLocal(current_position_);
+  len_push = PushLocal(string_param_length_);
+  StoreLocal(match_start_index_, Bind(Add(pos_push, len_push)));
+
+  pos_push = PushLocal(position_register(start_reg));
+  len_push = PushLocal(string_param_length_);
+  StoreLocal(capture_start_index_, Bind(Add(pos_push, len_push)));
+
+  pos_push = PushLocal(match_start_index_);
+  len_push = PushLocal(capture_length_);
+  StoreLocal(match_end_index_, Bind(Add(pos_push, len_push)));
+
+  BlockLabel success;
+  if (mode_ == ASCII) {
+    BlockLabel loop_increment;
+    BlockLabel loop;
+    BindBlock(&loop);
+
+    StoreLocal(char_in_capture_, CharacterAt(LoadLocal(capture_start_index_)));
+    StoreLocal(char_in_match_, CharacterAt(LoadLocal(match_start_index_)));
+
+    BranchOrBacktrack(Comparison(kEQ,
+                                 LoadLocal(char_in_capture_),
+                                 LoadLocal(char_in_match_)),
+                      &loop_increment);
+
+    // Mismatch, try case-insensitive match (converting letters to lower-case).
+    PushArgumentInstr* match_char_push = PushLocal(char_in_match_);
+    PushArgumentInstr* mask_push = PushArgument(Bind(Uint64Constant(0x20)));
+    StoreLocal(char_in_match_,
+               Bind(InstanceCall(
+                      InstanceCallDescriptor::FromToken(Token::kBIT_OR),
+                      match_char_push,
+                      mask_push)));
+
+    BlockLabel convert_capture;
+    BlockLabel on_not_in_range;
+    BranchOrBacktrack(Comparison(kLT,
+                                 LoadLocal(char_in_match_),
+                                 Uint64Constant('a')),
+                      &on_not_in_range);
+    BranchOrBacktrack(Comparison(kGT,
+                                 LoadLocal(char_in_match_),
+                                 Uint64Constant('z')),
+                      &on_not_in_range);
+    GoTo(&convert_capture);
+    BindBlock(&on_not_in_range);
+
+    // Latin-1: Check for values in range [224,254] but not 247.
+    BranchOrBacktrack(Comparison(kLT,
+                                 LoadLocal(char_in_match_),
+                                 Uint64Constant(224)),
+                      on_no_match);
+    BranchOrBacktrack(Comparison(kGT,
+                                 LoadLocal(char_in_match_),
+                                 Uint64Constant(254)),
+                      on_no_match);
+
+    BranchOrBacktrack(Comparison(kEQ,
+                                 LoadLocal(char_in_match_),
+                                 Uint64Constant(247)),
+                      on_no_match);
+
+    // Also convert capture character.
+    BindBlock(&convert_capture);
+
+    PushArgumentInstr* capture_char_push = PushLocal(char_in_capture_);
+    mask_push = PushArgument(Bind(Uint64Constant(0x20)));
+    StoreLocal(char_in_capture_,
+               Bind(InstanceCall(
+                      InstanceCallDescriptor::FromToken(Token::kBIT_OR),
+                      capture_char_push,
+                      mask_push)));
+
+    BranchOrBacktrack(Comparison(kNE,
+                                 LoadLocal(char_in_match_),
+                                 LoadLocal(char_in_capture_)),
+                      on_no_match);
+
+    BindBlock(&loop_increment);
+
+    // Increment pointers into match and capture strings.
+    StoreLocal(capture_start_index_, Bind(Add(
+                 PushLocal(capture_start_index_),
+                 PushArgument(Bind(Uint64Constant(1))))));
+    StoreLocal(match_start_index_, Bind(Add(
+                 PushLocal(match_start_index_),
+                 PushArgument(Bind(Uint64Constant(1))))));
+
+    // Compare to end of match, and loop if not done.
+    BranchOrBacktrack(Comparison(kLT,
+                                 LoadLocal(match_start_index_),
+                                 LoadLocal(match_end_index_)),
+                      &loop);
+  } else {
+    ASSERT(mode_ == UC16);
+
+    Value* string_value = Bind(LoadLocal(string_param_));
+    Value* lhs_index_value = Bind(LoadLocal(match_start_index_));
+    Value* rhs_index_value = Bind(LoadLocal(capture_start_index_));
+    Value* length_value = Bind(LoadLocal(capture_length_));
+
+    Definition* is_match_def =
+        new(I) CaseInsensitiveCompareUC16Instr(
+                            string_value,
+                            lhs_index_value,
+                            rhs_index_value,
+                            length_value,
+                            specialization_cid_);
+
+    BranchOrBacktrack(Comparison(kNE, is_match_def, BoolConstant(true)),
+                      on_no_match);
+  }
+
+  BindBlock(&success);
+
+  // Move current character position to position after match.
+  PushArgumentInstr* match_end_push = PushLocal(match_end_index_);
+  len_push = PushLocal(string_param_length_);
+  StoreLocal(current_position_, Bind(Sub(match_end_push, len_push)));
+
+  BindBlock(&fallthrough);
+}
+
+
+void IRRegExpMacroAssembler::CheckNotBackReference(
+    intptr_t start_reg,
+    BlockLabel* on_no_match) {
+  TAG();
+  ASSERT(start_reg + 1 <= position_registers_.length());
+
+  BlockLabel fallthrough;
+  BlockLabel success;
+
+  // Find length of back-referenced capture.
+  PushArgumentInstr* end_push = PushLocal(position_register(start_reg + 1));
+  PushArgumentInstr* start_push = PushLocal(position_register(start_reg));
+  StoreLocal(capture_length_, Bind(Sub(end_push, start_push)));
+
+  // Fail on partial or illegal capture (start of capture after end of capture).
+  BranchOrBacktrack(Comparison(kLT,
+                               LoadLocal(capture_length_),
+                               Uint64Constant(0)),
+                    on_no_match);
+
+  // Succeed on empty capture (including no capture)
+  BranchOrBacktrack(Comparison(kEQ,
+                               LoadLocal(capture_length_),
+                               Uint64Constant(0)),
+                    &fallthrough);
+
+  // Check that there are sufficient characters left in the input.
+  PushArgumentInstr* pos_push = PushLocal(current_position_);
+  PushArgumentInstr* len_push = PushLocal(capture_length_);
+  BranchOrBacktrack(
+        Comparison(kGT,
+                   InstanceCall(InstanceCallDescriptor::FromToken(Token::kADD),
+                                pos_push,
+                                len_push),
+                   Uint64Constant(0)),
+        on_no_match);
+
+  // Compute pointers to match string and capture string.
+  pos_push = PushLocal(current_position_);
+  len_push = PushLocal(string_param_length_);
+  StoreLocal(match_start_index_, Bind(Add(pos_push, len_push)));
+
+  pos_push = PushLocal(position_register(start_reg));
+  len_push = PushLocal(string_param_length_);
+  StoreLocal(capture_start_index_, Bind(Add(pos_push, len_push)));
+
+  pos_push = PushLocal(match_start_index_);
+  len_push = PushLocal(capture_length_);
+  StoreLocal(match_end_index_, Bind(Add(pos_push, len_push)));
+
+  BlockLabel loop;
+  BindBlock(&loop);
+
+  StoreLocal(char_in_capture_, CharacterAt(LoadLocal(capture_start_index_)));
+  StoreLocal(char_in_match_, CharacterAt(LoadLocal(match_start_index_)));
+
+  BranchOrBacktrack(Comparison(kNE,
+                               LoadLocal(char_in_capture_),
+                               LoadLocal(char_in_match_)),
+                    on_no_match);
+
+  // Increment pointers into capture and match string.
+  StoreLocal(capture_start_index_, Bind(Add(
+               PushLocal(capture_start_index_),
+               PushArgument(Bind(Uint64Constant(1))))));
+  StoreLocal(match_start_index_, Bind(Add(
+               PushLocal(match_start_index_),
+               PushArgument(Bind(Uint64Constant(1))))));
+
+  // Check if we have reached end of match area.
+  BranchOrBacktrack(Comparison(kLT,
+                               LoadLocal(match_start_index_),
+                               LoadLocal(match_end_index_)),
+                    &loop);
+
+  BindBlock(&success);
+
+  // Move current character position to position after match.
+  PushArgumentInstr* match_end_push = PushLocal(match_end_index_);
+  len_push = PushLocal(string_param_length_);
+  StoreLocal(current_position_, Bind(Sub(match_end_push, len_push)));
+
+  BindBlock(&fallthrough);
+}
+
+
+void IRRegExpMacroAssembler::CheckNotCharacter(uint32_t c,
+                                               BlockLabel* on_not_equal) {
+  TAG();
+  BranchOrBacktrack(Comparison(kNE,
+                               LoadLocal(current_character_),
+                               Uint64Constant(c)),
+                    on_not_equal);
+}
+
+
+void IRRegExpMacroAssembler::CheckCharacterAfterAnd(uint32_t c,
+                                                    uint32_t mask,
+                                                    BlockLabel* on_equal) {
+  TAG();
+
+  Definition* actual_def = LoadLocal(current_character_);
+  Definition* expected_def = Uint64Constant(c);
+
+  PushArgumentInstr* actual_push = PushArgument(Bind(actual_def));
+  PushArgumentInstr* mask_push = PushArgument(Bind(Uint64Constant(mask)));
+  actual_def = InstanceCall(InstanceCallDescriptor::FromToken(Token::kBIT_AND),
+                            actual_push,
+                            mask_push);
+
+  BranchOrBacktrack(Comparison(kEQ, actual_def, expected_def), on_equal);
+}
+
+
+void IRRegExpMacroAssembler::CheckNotCharacterAfterAnd(
+    uint32_t c,
+    uint32_t mask,
+    BlockLabel* on_not_equal) {
+  TAG();
+
+  Definition* actual_def = LoadLocal(current_character_);
+  Definition* expected_def = Uint64Constant(c);
+
+  PushArgumentInstr* actual_push = PushArgument(Bind(actual_def));
+  PushArgumentInstr* mask_push = PushArgument(Bind(Uint64Constant(mask)));
+  actual_def = InstanceCall(InstanceCallDescriptor::FromToken(Token::kBIT_AND),
+                            actual_push,
+                            mask_push);
+
+  BranchOrBacktrack(Comparison(kNE, actual_def, expected_def), on_not_equal);
+}
+
+
+void IRRegExpMacroAssembler::CheckNotCharacterAfterMinusAnd(
+    uint16_t c,
+    uint16_t minus,
+    uint16_t mask,
+    BlockLabel* on_not_equal) {
+  TAG();
+  ASSERT(minus < Utf16::kMaxCodeUnit);  // NOLINT
+
+  Definition* actual_def = LoadLocal(current_character_);
+  Definition* expected_def = Uint64Constant(c);
+
+  PushArgumentInstr* actual_push = PushArgument(Bind(actual_def));
+  PushArgumentInstr* minus_push = PushArgument(Bind(Uint64Constant(minus)));
+
+  actual_push = PushArgument(Bind(Sub(actual_push, minus_push)));
+  PushArgumentInstr* mask_push = PushArgument(Bind(Uint64Constant(mask)));
+  actual_def = InstanceCall(InstanceCallDescriptor::FromToken(Token::kBIT_AND),
+                            actual_push,
+                            mask_push);
+
+  BranchOrBacktrack(Comparison(kNE, actual_def, expected_def), on_not_equal);
+}
+
+
+void IRRegExpMacroAssembler::CheckCharacterInRange(
+    uint16_t from,
+    uint16_t to,
+    BlockLabel* on_in_range) {
+  TAG();
+  ASSERT(from <= to);
+
+  // TODO(jgruber): All range comparisons could be done cheaper with unsigned
+  // compares. This pattern repeats in various places.
+
+  BlockLabel on_not_in_range;
+  BranchOrBacktrack(Comparison(kLT,
+                               LoadLocal(current_character_),
+                               Uint64Constant(from)),
+                    &on_not_in_range);
+  BranchOrBacktrack(Comparison(kGT,
+                               LoadLocal(current_character_),
+                               Uint64Constant(to)),
+                    &on_not_in_range);
+  BranchOrBacktrack(NULL, on_in_range);
+
+  BindBlock(&on_not_in_range);
+}
+
+
+void IRRegExpMacroAssembler::CheckCharacterNotInRange(
+    uint16_t from,
+    uint16_t to,
+    BlockLabel* on_not_in_range) {
+  TAG();
+  ASSERT(from <= to);
+
+  BranchOrBacktrack(Comparison(kLT,
+                               LoadLocal(current_character_),
+                               Uint64Constant(from)),
+                    on_not_in_range);
+
+  BranchOrBacktrack(Comparison(kGT,
+                               LoadLocal(current_character_),
+                               Uint64Constant(to)),
+                    on_not_in_range);
+}
+
+
+void IRRegExpMacroAssembler::CheckBitInTable(
+    const TypedData& table,
+    BlockLabel* on_bit_set) {
+  TAG();
+
+  PushArgumentInstr* table_push =
+      PushArgument(Bind(new(I) ConstantInstr(table)));
+  PushArgumentInstr* index_push = PushLocal(current_character_);
+
+  if (mode_ != ASCII || kTableMask != Symbols::kMaxOneCharCodeSymbol) {
+    PushArgumentInstr* mask_push =
+        PushArgument(Bind(Uint64Constant(kTableSize - 1)));
+    index_push = PushArgument(
+          Bind(InstanceCall(InstanceCallDescriptor::FromToken(Token::kBIT_AND),
+                            index_push,
+                            mask_push)));
+  }
+
+  Definition* byte_def =
+      InstanceCall(InstanceCallDescriptor::FromToken(Token::kINDEX),
+                   table_push,
+                   index_push);
+  Definition* zero_def = Int64Constant(0);
+
+  BranchOrBacktrack(Comparison(kNE, byte_def, zero_def), on_bit_set);
+}
+
+
+bool IRRegExpMacroAssembler::CheckSpecialCharacterClass(
+    uint16_t type,
+    BlockLabel* on_no_match) {
+  TAG();
+
+  // Range checks (c in min..max) are generally implemented by an unsigned
+  // (c - min) <= (max - min) check
+  switch (type) {
+  case 's':
+    // Match space-characters
+    if (mode_ == ASCII) {
+      // One byte space characters are '\t'..'\r', ' ' and \u00a0.
+      BlockLabel success;
+      // Space (' ').
+      BranchOrBacktrack(Comparison(kEQ,
+                                   LoadLocal(current_character_),
+                                   Uint64Constant(' ')),
+                        &success);
+      // Check range 0x09..0x0d.
+      CheckCharacterInRange('\t', '\r', &success);
+      // \u00a0 (NBSP).
+      BranchOrBacktrack(Comparison(kNE,
+                                   LoadLocal(current_character_),
+                                   Uint64Constant(0x00a0)),
+                        on_no_match);
+      BindBlock(&success);
+      return true;
+    }
+    return false;
+  case 'S':
+    // The emitted code for generic character classes is good enough.
+    return false;
+  case 'd':
+    // Match ASCII digits ('0'..'9')
+    CheckCharacterNotInRange('0', '9', on_no_match);
+    return true;
+  case 'D':
+    // Match non ASCII-digits
+    CheckCharacterInRange('0', '9', on_no_match);
+    return true;
+  case '.': {
+    // Match non-newlines (not 0x0a('\n'), 0x0d('\r'), 0x2028 and 0x2029)
+    BranchOrBacktrack(Comparison(kEQ,
+                                 LoadLocal(current_character_),
+                                 Uint64Constant('\n')),
+                      on_no_match);
+    BranchOrBacktrack(Comparison(kEQ,
+                                 LoadLocal(current_character_),
+                                 Uint64Constant('\r')),
+                      on_no_match);
+    if (mode_ == UC16) {
+      BranchOrBacktrack(Comparison(kEQ,
+                                   LoadLocal(current_character_),
+                                   Uint64Constant(0x2028)),
+                        on_no_match);
+      BranchOrBacktrack(Comparison(kEQ,
+                                   LoadLocal(current_character_),
+                                   Uint64Constant(0x2029)),
+                        on_no_match);
+    }
+    return true;
+  }
+  case 'w': {
+    if (mode_ != ASCII) {
+      // Table is 128 entries, so all ASCII characters can be tested.
+      BranchOrBacktrack(Comparison(kGT,
+                                   LoadLocal(current_character_),
+                                   Uint64Constant('z')),
+                        on_no_match);
+    }
+
+    PushArgumentInstr* table_push =
+        PushArgument(Bind(WordCharacterMapConstant()));
+    PushArgumentInstr* index_push = PushLocal(current_character_);
+
+    Definition* byte_def =
+        InstanceCall(InstanceCallDescriptor::FromToken(Token::kINDEX),
+                     table_push,
+                     index_push);
+    Definition* zero_def = Int64Constant(0);
+
+    BranchOrBacktrack(Comparison(kEQ, byte_def, zero_def), on_no_match);
+
+    return true;
+  }
+  case 'W': {
+    BlockLabel done;
+    if (mode_ != ASCII) {
+      // Table is 128 entries, so all ASCII characters can be tested.
+      BranchOrBacktrack(Comparison(kGT,
+                                   LoadLocal(current_character_),
+                                   Uint64Constant('z')),
+                        &done);
+    }
+
+    // TODO(jgruber): Refactor to use CheckBitInTable if possible.
+
+    PushArgumentInstr* table_push =
+        PushArgument(Bind(WordCharacterMapConstant()));
+    PushArgumentInstr* index_push = PushLocal(current_character_);
+
+    Definition* byte_def =
+        InstanceCall(InstanceCallDescriptor::FromToken(Token::kINDEX),
+                     table_push,
+                     index_push);
+    Definition* zero_def = Int64Constant(0);
+
+    BranchOrBacktrack(Comparison(kNE, byte_def, zero_def), on_no_match);
+
+    if (mode_ != ASCII) {
+      BindBlock(&done);
+    }
+    return true;
+  }
+  // Non-standard classes (with no syntactic shorthand) used internally.
+  case '*':
+    // Match any character.
+    return true;
+  case 'n': {
+    // Match newlines (0x0a('\n'), 0x0d('\r'), 0x2028 or 0x2029).
+    // The opposite of '.'.
+    BlockLabel success;
+    BranchOrBacktrack(Comparison(kEQ,
+                                 LoadLocal(current_character_),
+                                 Uint64Constant('\n')),
+                      &success);
+    BranchOrBacktrack(Comparison(kEQ,
+                                 LoadLocal(current_character_),
+                                 Uint64Constant('\r')),
+                      &success);
+    if (mode_ == UC16) {
+      BranchOrBacktrack(Comparison(kEQ,
+                                   LoadLocal(current_character_),
+                                   Uint64Constant(0x2028)),
+                        &success);
+      BranchOrBacktrack(Comparison(kEQ,
+                                   LoadLocal(current_character_),
+                                   Uint64Constant(0x2029)),
+                        &success);
+    }
+    BranchOrBacktrack(NULL, on_no_match);
+    BindBlock(&success);
+    return true;
+  }
+  // No custom implementation (yet): s(uint16_t), S(uint16_t).
+  default:
+    return false;
+  }
+}
+
+
+void IRRegExpMacroAssembler::Fail() {
+  TAG();
+  ASSERT(FAILURE == 0);  // Return value for failure is zero.
+  if (!global()) {
+    UNREACHABLE();  // Dart regexps are always global.
+  }
+  GoTo(exit_block_);
+}
+
+
+void IRRegExpMacroAssembler::IfRegisterGE(intptr_t reg,
+                                          intptr_t comparand,
+                                          BlockLabel* if_ge) {
+  TAG();
+  BranchOrBacktrack(Comparison(kGTE,
+                               LoadLocal(position_register(reg)),
+                               Int64Constant(comparand)),
+                    if_ge);
+}
+
+
+void IRRegExpMacroAssembler::IfRegisterLT(intptr_t reg,
+                                          intptr_t comparand,
+                                          BlockLabel* if_lt) {
+  TAG();
+  BranchOrBacktrack(Comparison(kLT,
+                               LoadLocal(position_register(reg)),
+                               Int64Constant(comparand)),
+                    if_lt);
+}
+
+
+void IRRegExpMacroAssembler::IfRegisterEqPos(intptr_t reg,
+                                             BlockLabel* if_eq) {
+  TAG();
+  BranchOrBacktrack(Comparison(kEQ,
+                               LoadLocal(position_register(reg)),
+                               LoadLocal(current_position_)),
+                    if_eq);
+}
+
+
+RegExpMacroAssembler::IrregexpImplementation
+    IRRegExpMacroAssembler::Implementation() {
+  return kIRImplementation;
+}
+
+
+void IRRegExpMacroAssembler::LoadCurrentCharacter(intptr_t cp_offset,
+                                                  BlockLabel* on_end_of_input,
+                                                  bool check_bounds,
+                                                  intptr_t characters) {
+  TAG();
+  ASSERT(cp_offset >= -1);      // ^ and \b can look behind one character.
+  ASSERT(cp_offset < (1<<30));  // Be sane! (And ensure negation works)
+  if (check_bounds) {
+    CheckPosition(cp_offset + characters - 1, on_end_of_input);
+  }
+  LoadCurrentCharacterUnchecked(cp_offset, characters);
+}
+
+
+void IRRegExpMacroAssembler::PopCurrentPosition() {
+  TAG();
+  StoreLocal(current_position_, PopStack());
+}
+
+
+void IRRegExpMacroAssembler::PopRegister(intptr_t register_index) {
+  TAG();
+  ASSERT(register_index < position_registers_.length());
+  StoreLocal(position_register(register_index), PopStack());
+}
+
+
+void IRRegExpMacroAssembler::PushStack(Definition *definition) {
+  PushArgumentInstr* stack_push = PushLocal(stack_);
+  PushArgumentInstr* value_push = PushArgument(Bind(definition));
+  Do(InstanceCall(InstanceCallDescriptor(Symbols::add()),
+                  stack_push,
+                  value_push));
+}
+
+
+Value* IRRegExpMacroAssembler::PopStack() {
+  PushArgumentInstr* stack_push = PushLocal(stack_);
+  return Bind(InstanceCall(InstanceCallDescriptor(Symbols::removeLast()),
+                           stack_push));
+}
+
+
+// Pushes the location corresponding to label to the backtracking stack.
+void IRRegExpMacroAssembler::PushBacktrack(BlockLabel* label) {
+  TAG();
+
+  // Ensure that targets of indirect jumps are never accessed through a
+  // normal control flow instructions by creating a new block for each backtrack
+  // target.
+  IndirectEntryInstr* indirect_target = IndirectWithJoinGoto(label->block());
+
+  // Add a fake edge from the graph entry for data flow analysis.
+  entry_block_->AddIndirectEntry(indirect_target);
+
+  ConstantInstr* offset = Uint64Constant(indirect_target->indirect_id());
+  PushStack(offset);
+}
+
+
+void IRRegExpMacroAssembler::PushCurrentPosition() {
+  TAG();
+  PushStack(LoadLocal(current_position_));
+}
+
+
+void IRRegExpMacroAssembler::PushRegister(intptr_t register_index) {
+  TAG();
+  PushStack(LoadLocal(position_register(register_index)));
+}
+
+
+void IRRegExpMacroAssembler::ReadCurrentPositionFromRegister(intptr_t reg) {
+  TAG();
+  StoreLocal(current_position_, Bind(LoadLocal(position_register(reg))));
+}
+
+// Resets the size of the stack to the value stored in reg.
+void IRRegExpMacroAssembler::ReadStackPointerFromRegister(intptr_t reg) {
+  TAG();
+  ASSERT(reg < position_registers_.length());
+
+  PushArgumentInstr* stack_push = PushLocal(stack_);
+  PushArgumentInstr* length_push = PushLocal(position_register(reg));
+
+  Do(InstanceCall(InstanceCallDescriptor(
+                    String::ZoneHandle(
+                      I, Field::SetterSymbol(Symbols::Length()))),
+                  stack_push,
+                  length_push));
+}
+
+void IRRegExpMacroAssembler::SetCurrentPositionFromEnd(intptr_t by)  {
+  TAG();
+
+  BlockLabel after_position;
+
+  Definition* cur_pos_def = LoadLocal(current_position_);
+  Definition* by_value_def = Int64Constant(-by);
+
+  BranchOrBacktrack(Comparison(kGTE, cur_pos_def, by_value_def),
+                    &after_position);
+
+  StoreLocal(current_position_, Bind(Int64Constant(-by)));
+
+  // On RegExp code entry (where this operation is used), the character before
+  // the current position is expected to be already loaded.
+  // We have advanced the position, so it's safe to read backwards.
+  LoadCurrentCharacterUnchecked(-1, 1);
+
+  BindBlock(&after_position);
+}
+
+
+void IRRegExpMacroAssembler::SetRegister(intptr_t register_index, intptr_t to) {
+  TAG();
+  // Reserved for positions!
+  ASSERT(register_index >= position_registers_count_);
+  StoreLocal(position_register(register_index), Bind(Int64Constant(to)));
+}
+
+
+bool IRRegExpMacroAssembler::Succeed() {
+  TAG();
+  GoTo(success_block_);
+  return global();
+}
+
+
+void IRRegExpMacroAssembler::WriteCurrentPositionToRegister(
+    intptr_t reg, intptr_t cp_offset) {
+  TAG();
+
+  PushArgumentInstr* pos_push = PushLocal(current_position_);
+  PushArgumentInstr* off_push =
+      PushArgument(Bind(Int64Constant(cp_offset)));
+
+  // Push the negative offset; these are converted to positive string positions
+  // within the success block.
+  StoreLocal(position_register(reg), Bind(Add(pos_push, off_push)));
+}
+
+
+void IRRegExpMacroAssembler::ClearRegisters(
+    intptr_t reg_from, intptr_t reg_to) {
+  TAG();
+
+  ASSERT(reg_from <= reg_to);
+  ASSERT(reg_to < position_registers_.length());
+
+  // In order to clear registers to a final result value of -1, set them to
+  // (-1 - string length), the offset of -1 from the end of the string.
+
+  for (intptr_t reg = reg_from; reg <= reg_to; reg++) {
+    PushArgumentInstr* minus_one_push =
+        PushArgument(Bind(Int64Constant(-1)));
+    PushArgumentInstr* length_push = PushLocal(string_param_length_);
+
+    StoreLocal(position_register(reg), Bind(Sub(minus_one_push, length_push)));
+  }
+}
+
+
+void IRRegExpMacroAssembler::WriteStackPointerToRegister(intptr_t reg) {
+  TAG();
+
+  PushArgumentInstr* stack_push = PushLocal(stack_);
+  Value* length_value =
+      Bind(InstanceCall(InstanceCallDescriptor(
+                          String::ZoneHandle(
+                            I, Field::GetterSymbol(Symbols::Length()))),
+                        stack_push));
+
+  StoreLocal(position_register(reg), length_value);
+}
+
+
+// Private methods:
+
+
+void IRRegExpMacroAssembler::CheckPosition(intptr_t cp_offset,
+                                           BlockLabel* on_outside_input) {
+  TAG();
+  Definition* curpos_def = LoadLocal(current_position_);
+  Definition* cp_off_def = Int64Constant(-cp_offset);
+
+  // If (current_position_ < -cp_offset), we are in bounds.
+  // Remember, current_position_ is a negative offset from the string end.
+
+  BranchOrBacktrack(Comparison(kGTE, curpos_def, cp_off_def),
+                    on_outside_input);
+}
+
+
+void IRRegExpMacroAssembler::BranchOrBacktrack(
+    ComparisonInstr* comparison,
+    BlockLabel* true_successor) {
+  if (comparison == NULL) {  // No condition
+    if (true_successor == NULL) {
+      Backtrack();
+      return;
+    }
+    GoTo(true_successor);
+    return;
+  }
+
+  // If no successor block has been passed in, backtrack.
+  JoinEntryInstr* true_successor_block = backtrack_block_;
+  if (true_successor != NULL) {
+    true_successor->SetLinked();
+    true_successor_block = true_successor->block();
+  }
+  ASSERT(true_successor_block != NULL);
+
+  // If the condition is not true, fall through to a new block.
+  BlockLabel fallthrough;
+
+  BranchInstr* branch = new(I) BranchInstr(comparison);
+  *branch->true_successor_address() =
+      TargetWithJoinGoto(true_successor_block);
+  *branch->false_successor_address() =
+      TargetWithJoinGoto(fallthrough.block());
+
+  CloseBlockWith(branch);
+  BindBlock(&fallthrough);
+}
+
+
+TargetEntryInstr* IRRegExpMacroAssembler::TargetWithJoinGoto(
+    JoinEntryInstr* dst) {
+  TargetEntryInstr* target = new(I) TargetEntryInstr(
+          block_id_.Alloc(), kInvalidTryIndex);
+  blocks_.Add(target);
+
+  target->AppendInstruction(new(I) GotoInstr(dst));
+
+  return target;
+}
+
+
+IndirectEntryInstr* IRRegExpMacroAssembler::IndirectWithJoinGoto(
+    JoinEntryInstr* dst) {
+  IndirectEntryInstr* target = new(I) IndirectEntryInstr(
+          block_id_.Alloc(), indirect_id_.Alloc(), kInvalidTryIndex);
+  blocks_.Add(target);
+
+  target->AppendInstruction(new(I) GotoInstr(dst));
+
+  return target;
+}
+
+
+void IRRegExpMacroAssembler::CheckPreemption() {
+  TAG();
+  AppendInstruction(new(I) CheckStackOverflowInstr(kNoTokenPos, 0));
+}
+
+
+Definition* IRRegExpMacroAssembler::Add(
+    PushArgumentInstr* lhs,
+    PushArgumentInstr* rhs) {
+  return InstanceCall(InstanceCallDescriptor::FromToken(Token::kADD), lhs, rhs);
+}
+
+
+Definition* IRRegExpMacroAssembler::Sub(
+    PushArgumentInstr* lhs,
+    PushArgumentInstr* rhs) {
+  return InstanceCall(InstanceCallDescriptor::FromToken(Token::kSUB), lhs, rhs);
+}
+
+
+static const String& codeUnitsAtName(intptr_t characters) {
+  switch (characters) {
+    case 1: return Library::PrivateCoreLibName(Symbols::_oneCodeUnitAt());
+    case 2: return Library::PrivateCoreLibName(Symbols::_twoCodeUnitsAt());
+    case 4: return Library::PrivateCoreLibName(Symbols::_fourCodeUnitsAt());
+  }
+  UNREACHABLE();
+  return String::Handle();
+}
+
+
+void IRRegExpMacroAssembler::LoadCurrentCharacterUnchecked(
+    intptr_t cp_offset, intptr_t characters) {
+  TAG();
+
+  if (mode_ == ASCII) {
+    ASSERT(characters == 1 || characters == 2 || characters == 4);
+  } else {
+    ASSERT(mode_ == UC16);
+    ASSERT(characters == 1 || characters == 2);
+  }
+
+  // LoadLocal pattern_param_
+  // PushArgument()
+  PushArgumentInstr* pattern_push = PushLocal(string_param_);
+
+  // Calculate the addressed string index as
+  //    cp_offset + current_position_ + string_param_length_
+  PushArgumentInstr* cp_offset_push =
+      PushArgument(Bind(Int64Constant(cp_offset)));
+  PushArgumentInstr* cur_pos_push = PushLocal(current_position_);
+
+  PushArgumentInstr* partial_sum_push =
+      PushArgument(Bind(Add(cp_offset_push, cur_pos_push)));
+  PushArgumentInstr* length_push = PushLocal(string_param_length_);
+
+  PushArgumentInstr* pos_push =
+      PushArgument(Bind(Add(partial_sum_push, length_push)));
+
+  // InstanceCall(codeUnitAt, t0, t0)
+  const String& name = codeUnitsAtName(characters);
+  Value* code_unit_value =
+      Bind(InstanceCall(InstanceCallDescriptor(name),
+                        pattern_push,
+                        pos_push));
+
+  // StoreLocal(current_character_)
+  StoreLocal(current_character_, code_unit_value);
+
+  PRINT(PushLocal(current_character_));
+}
+
+
+Value* IRRegExpMacroAssembler::CharacterAt(Definition* index) {
+  PushArgumentInstr* pattern_push = PushLocal(string_param_);
+  PushArgumentInstr* index_push = PushArgument(Bind(index));
+
+  return Bind(InstanceCall(InstanceCallDescriptor(codeUnitsAtName(1)),
+                           pattern_push,
+                           index_push));
+}
+
+
+#undef __
+
+}  // namespace dart