Imported v8 version 3.7.3 from https://github.com/v8/v8.git

Change-Id: I152648081e46f599c2bb88eaaf67034fa5daac3a

1 files changed, 1069 insertions, 0 deletions

diff --git a/src/3rdparty/v8/src/code-stubs.h b/src/3rdparty/v8/src/code-stubs.h
new file mode 100644
index 0000000..fc7000b
--- /dev/null
+++ b/src/3rdparty/v8/src/code-stubs.h
@@ -0,0 +1,1069 @@
+// Copyright 2011 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.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_CODE_STUBS_H_
+#define V8_CODE_STUBS_H_
+
+#include "allocation.h"
+#include "globals.h"
+#include "codegen.h"
+
+namespace v8 {
+namespace internal {
+
+// List of code stubs used on all platforms.
+#define CODE_STUB_LIST_ALL_PLATFORMS(V)  \
+  V(CallFunction)                        \
+  V(UnaryOp)                             \
+  V(BinaryOp)                            \
+  V(StringAdd)                           \
+  V(SubString)                           \
+  V(StringCompare)                       \
+  V(Compare)                             \
+  V(CompareIC)                           \
+  V(MathPow)                             \
+  V(RecordWrite)                         \
+  V(StoreBufferOverflow)                 \
+  V(RegExpExec)                          \
+  V(TranscendentalCache)                 \
+  V(Instanceof)                          \
+  V(ConvertToDouble)                     \
+  V(WriteInt32ToHeapNumber)              \
+  V(StackCheck)                          \
+  V(FastNewClosure)                      \
+  V(FastNewContext)                      \
+  V(FastNewBlockContext)                 \
+  V(FastCloneShallowArray)               \
+  V(RevertToNumber)                      \
+  V(ToBoolean)                           \
+  V(ToNumber)                            \
+  V(CounterOp)                           \
+  V(ArgumentsAccess)                     \
+  V(RegExpConstructResult)               \
+  V(NumberToString)                      \
+  V(CEntry)                              \
+  V(JSEntry)                             \
+  V(KeyedLoadElement)                    \
+  V(KeyedStoreElement)                   \
+  V(DebuggerStatement)                   \
+  V(StringDictionaryLookup)              \
+  V(ElementsTransitionAndStore)
+
+// List of code stubs only used on ARM platforms.
+#ifdef V8_TARGET_ARCH_ARM
+#define CODE_STUB_LIST_ARM(V)  \
+  V(GetProperty)               \
+  V(SetProperty)               \
+  V(InvokeBuiltin)             \
+  V(RegExpCEntry)              \
+  V(DirectCEntry)
+#else
+#define CODE_STUB_LIST_ARM(V)
+#endif
+
+// List of code stubs only used on MIPS platforms.
+#ifdef V8_TARGET_ARCH_MIPS
+#define CODE_STUB_LIST_MIPS(V)  \
+  V(RegExpCEntry)               \
+  V(DirectCEntry)
+#else
+#define CODE_STUB_LIST_MIPS(V)
+#endif
+
+// Combined list of code stubs.
+#define CODE_STUB_LIST(V)            \
+  CODE_STUB_LIST_ALL_PLATFORMS(V)    \
+  CODE_STUB_LIST_ARM(V)              \
+  CODE_STUB_LIST_MIPS(V)
+
+// Mode to overwrite BinaryExpression values.
+enum OverwriteMode { NO_OVERWRITE, OVERWRITE_LEFT, OVERWRITE_RIGHT };
+enum UnaryOverwriteMode { UNARY_OVERWRITE, UNARY_NO_OVERWRITE };
+
+
+// Stub is base classes of all stubs.
+class CodeStub BASE_EMBEDDED {
+ public:
+  enum Major {
+#define DEF_ENUM(name) name,
+    CODE_STUB_LIST(DEF_ENUM)
+#undef DEF_ENUM
+    NoCache,  // marker for stubs that do custom caching
+    NUMBER_OF_IDS
+  };
+
+  // Retrieve the code for the stub. Generate the code if needed.
+  Handle<Code> GetCode();
+
+  // Retrieve the code for the stub if already generated.  Do not
+  // generate the code if not already generated and instead return a
+  // retry after GC Failure object.
+  MUST_USE_RESULT MaybeObject* TryGetCode();
+
+  static Major MajorKeyFromKey(uint32_t key) {
+    return static_cast<Major>(MajorKeyBits::decode(key));
+  }
+  static int MinorKeyFromKey(uint32_t key) {
+    return MinorKeyBits::decode(key);
+  }
+
+  // Gets the major key from a code object that is a code stub or binary op IC.
+  static Major GetMajorKey(Code* code_stub) {
+    return static_cast<Major>(code_stub->major_key());
+  }
+
+  static const char* MajorName(Major major_key, bool allow_unknown_keys);
+
+  virtual ~CodeStub() {}
+
+  bool CompilingCallsToThisStubIsGCSafe() {
+    bool is_pregenerated = IsPregenerated();
+    Code* code = NULL;
+    CHECK(!is_pregenerated || FindCodeInCache(&code));
+    return is_pregenerated;
+  }
+
+  // See comment above, where Instanceof is defined.
+  virtual bool IsPregenerated() { return false; }
+
+  static void GenerateStubsAheadOfTime();
+  static void GenerateFPStubs();
+
+  // Some stubs put untagged junk on the stack that cannot be scanned by the
+  // GC.  This means that we must be statically sure that no GC can occur while
+  // they are running.  If that is the case they should override this to return
+  // true, which will cause an assertion if we try to call something that can
+  // GC or if we try to put a stack frame on top of the junk, which would not
+  // result in a traversable stack.
+  virtual bool SometimesSetsUpAFrame() { return true; }
+
+ protected:
+  static const int kMajorBits = 6;
+  static const int kMinorBits = kBitsPerInt - kSmiTagSize - kMajorBits;
+
+ private:
+  // Lookup the code in the (possibly custom) cache.
+  bool FindCodeInCache(Code** code_out);
+
+  // Nonvirtual wrapper around the stub-specific Generate function.  Call
+  // this function to set up the macro assembler and generate the code.
+  void GenerateCode(MacroAssembler* masm);
+
+  // Generates the assembler code for the stub.
+  virtual void Generate(MacroAssembler* masm) = 0;
+
+  // Perform bookkeeping required after code generation when stub code is
+  // initially generated.
+  void RecordCodeGeneration(Code* code, MacroAssembler* masm);
+
+  // Finish the code object after it has been generated.
+  virtual void FinishCode(Code* code) { }
+
+  // Returns true if TryGetCode should fail if it failed
+  // to register newly generated stub in the stub cache.
+  virtual bool MustBeInStubCache() { return false; }
+
+  // Activate newly generated stub. Is called after
+  // registering stub in the stub cache.
+  virtual void Activate(Code* code) { }
+
+  // Returns information for computing the number key.
+  virtual Major MajorKey() = 0;
+  virtual int MinorKey() = 0;
+
+  // BinaryOpStub needs to override this.
+  virtual int GetCodeKind();
+
+  // BinaryOpStub needs to override this.
+  virtual InlineCacheState GetICState() {
+    return UNINITIALIZED;
+  }
+
+  // Returns a name for logging/debugging purposes.
+  SmartArrayPointer<const char> GetName();
+  virtual void PrintName(StringStream* stream);
+
+  // Returns whether the code generated for this stub needs to be allocated as
+  // a fixed (non-moveable) code object.
+  virtual bool NeedsImmovableCode() { return false; }
+
+  // Computes the key based on major and minor.
+  uint32_t GetKey() {
+    ASSERT(static_cast<int>(MajorKey()) < NUMBER_OF_IDS);
+    return MinorKeyBits::encode(MinorKey()) |
+           MajorKeyBits::encode(MajorKey());
+  }
+
+  class MajorKeyBits: public BitField<uint32_t, 0, kMajorBits> {};
+  class MinorKeyBits: public BitField<uint32_t, kMajorBits, kMinorBits> {};
+
+  friend class BreakPointIterator;
+};
+
+
+// Helper interface to prepare to/restore after making runtime calls.
+class RuntimeCallHelper {
+ public:
+  virtual ~RuntimeCallHelper() {}
+
+  virtual void BeforeCall(MacroAssembler* masm) const = 0;
+
+  virtual void AfterCall(MacroAssembler* masm) const = 0;
+
+ protected:
+  RuntimeCallHelper() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(RuntimeCallHelper);
+};
+
+} }  // namespace v8::internal
+
+#if V8_TARGET_ARCH_IA32
+#include "ia32/code-stubs-ia32.h"
+#elif V8_TARGET_ARCH_X64
+#include "x64/code-stubs-x64.h"
+#elif V8_TARGET_ARCH_ARM
+#include "arm/code-stubs-arm.h"
+#elif V8_TARGET_ARCH_MIPS
+#include "mips/code-stubs-mips.h"
+#else
+#error Unsupported target architecture.
+#endif
+
+namespace v8 {
+namespace internal {
+
+
+// RuntimeCallHelper implementation used in stubs: enters/leaves a
+// newly created internal frame before/after the runtime call.
+class StubRuntimeCallHelper : public RuntimeCallHelper {
+ public:
+  StubRuntimeCallHelper() {}
+
+  virtual void BeforeCall(MacroAssembler* masm) const;
+
+  virtual void AfterCall(MacroAssembler* masm) const;
+};
+
+
+// Trivial RuntimeCallHelper implementation.
+class NopRuntimeCallHelper : public RuntimeCallHelper {
+ public:
+  NopRuntimeCallHelper() {}
+
+  virtual void BeforeCall(MacroAssembler* masm) const {}
+
+  virtual void AfterCall(MacroAssembler* masm) const {}
+};
+
+
+class StackCheckStub : public CodeStub {
+ public:
+  StackCheckStub() { }
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  Major MajorKey() { return StackCheck; }
+  int MinorKey() { return 0; }
+};
+
+
+class ToNumberStub: public CodeStub {
+ public:
+  ToNumberStub() { }
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  Major MajorKey() { return ToNumber; }
+  int MinorKey() { return 0; }
+};
+
+
+class FastNewClosureStub : public CodeStub {
+ public:
+  explicit FastNewClosureStub(StrictModeFlag strict_mode)
+    : strict_mode_(strict_mode) { }
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  Major MajorKey() { return FastNewClosure; }
+  int MinorKey() { return strict_mode_; }
+
+  StrictModeFlag strict_mode_;
+};
+
+
+class FastNewContextStub : public CodeStub {
+ public:
+  static const int kMaximumSlots = 64;
+
+  explicit FastNewContextStub(int slots) : slots_(slots) {
+    ASSERT(slots_ > 0 && slots_ <= kMaximumSlots);
+  }
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  int slots_;
+
+  Major MajorKey() { return FastNewContext; }
+  int MinorKey() { return slots_; }
+};
+
+
+class FastNewBlockContextStub : public CodeStub {
+ public:
+  static const int kMaximumSlots = 64;
+
+  explicit FastNewBlockContextStub(int slots) : slots_(slots) {
+    ASSERT(slots_ > 0 && slots_ <= kMaximumSlots);
+  }
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  int slots_;
+
+  Major MajorKey() { return FastNewBlockContext; }
+  int MinorKey() { return slots_; }
+};
+
+
+class FastCloneShallowArrayStub : public CodeStub {
+ public:
+  // Maximum length of copied elements array.
+  static const int kMaximumClonedLength = 8;
+
+  enum Mode {
+    CLONE_ELEMENTS,
+    CLONE_DOUBLE_ELEMENTS,
+    COPY_ON_WRITE_ELEMENTS
+  };
+
+  FastCloneShallowArrayStub(Mode mode, int length)
+      : mode_(mode),
+        length_((mode == COPY_ON_WRITE_ELEMENTS) ? 0 : length) {
+    ASSERT(length_ >= 0);
+    ASSERT(length_ <= kMaximumClonedLength);
+  }
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  Mode mode_;
+  int length_;
+
+  Major MajorKey() { return FastCloneShallowArray; }
+  int MinorKey() {
+    ASSERT(mode_ == 0 || mode_ == 1 || mode_ == 2);
+    return length_ * 3 +  mode_;
+  }
+};
+
+
+class InstanceofStub: public CodeStub {
+ public:
+  enum Flags {
+    kNoFlags = 0,
+    kArgsInRegisters = 1 << 0,
+    kCallSiteInlineCheck = 1 << 1,
+    kReturnTrueFalseObject = 1 << 2
+  };
+
+  explicit InstanceofStub(Flags flags) : flags_(flags) { }
+
+  static Register left();
+  static Register right();
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  Major MajorKey() { return Instanceof; }
+  int MinorKey() { return static_cast<int>(flags_); }
+
+  bool HasArgsInRegisters() const {
+    return (flags_ & kArgsInRegisters) != 0;
+  }
+
+  bool HasCallSiteInlineCheck() const {
+    return (flags_ & kCallSiteInlineCheck) != 0;
+  }
+
+  bool ReturnTrueFalseObject() const {
+    return (flags_ & kReturnTrueFalseObject) != 0;
+  }
+
+  virtual void PrintName(StringStream* stream);
+
+  Flags flags_;
+};
+
+
+class MathPowStub: public CodeStub {
+ public:
+  MathPowStub() {}
+  virtual void Generate(MacroAssembler* masm);
+
+ private:
+  virtual CodeStub::Major MajorKey() { return MathPow; }
+  virtual int MinorKey() { return 0; }
+};
+
+
+class ICCompareStub: public CodeStub {
+ public:
+  ICCompareStub(Token::Value op, CompareIC::State state)
+      : op_(op), state_(state) {
+    ASSERT(Token::IsCompareOp(op));
+  }
+
+  virtual void Generate(MacroAssembler* masm);
+
+ private:
+  class OpField: public BitField<int, 0, 3> { };
+  class StateField: public BitField<int, 3, 5> { };
+
+  virtual void FinishCode(Code* code) { code->set_compare_state(state_); }
+
+  virtual CodeStub::Major MajorKey() { return CompareIC; }
+  virtual int MinorKey();
+
+  virtual int GetCodeKind() { return Code::COMPARE_IC; }
+
+  void GenerateSmis(MacroAssembler* masm);
+  void GenerateHeapNumbers(MacroAssembler* masm);
+  void GenerateSymbols(MacroAssembler* masm);
+  void GenerateStrings(MacroAssembler* masm);
+  void GenerateObjects(MacroAssembler* masm);
+  void GenerateMiss(MacroAssembler* masm);
+
+  bool strict() const { return op_ == Token::EQ_STRICT; }
+  Condition GetCondition() const { return CompareIC::ComputeCondition(op_); }
+
+  Token::Value op_;
+  CompareIC::State state_;
+};
+
+
+// Flags that control the compare stub code generation.
+enum CompareFlags {
+  NO_COMPARE_FLAGS = 0,
+  NO_SMI_COMPARE_IN_STUB = 1 << 0,
+  NO_NUMBER_COMPARE_IN_STUB = 1 << 1,
+  CANT_BOTH_BE_NAN = 1 << 2
+};
+
+
+enum NaNInformation {
+  kBothCouldBeNaN,
+  kCantBothBeNaN
+};
+
+
+class CompareStub: public CodeStub {
+ public:
+  CompareStub(Condition cc,
+              bool strict,
+              CompareFlags flags,
+              Register lhs,
+              Register rhs) :
+     cc_(cc),
+      strict_(strict),
+      never_nan_nan_((flags & CANT_BOTH_BE_NAN) != 0),
+      include_number_compare_((flags & NO_NUMBER_COMPARE_IN_STUB) == 0),
+      include_smi_compare_((flags & NO_SMI_COMPARE_IN_STUB) == 0),
+      lhs_(lhs),
+      rhs_(rhs) { }
+
+  CompareStub(Condition cc,
+              bool strict,
+              CompareFlags flags) :
+      cc_(cc),
+      strict_(strict),
+      never_nan_nan_((flags & CANT_BOTH_BE_NAN) != 0),
+      include_number_compare_((flags & NO_NUMBER_COMPARE_IN_STUB) == 0),
+      include_smi_compare_((flags & NO_SMI_COMPARE_IN_STUB) == 0),
+      lhs_(no_reg),
+      rhs_(no_reg) { }
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  Condition cc_;
+  bool strict_;
+  // Only used for 'equal' comparisons.  Tells the stub that we already know
+  // that at least one side of the comparison is not NaN.  This allows the
+  // stub to use object identity in the positive case.  We ignore it when
+  // generating the minor key for other comparisons to avoid creating more
+  // stubs.
+  bool never_nan_nan_;
+  // Do generate the number comparison code in the stub. Stubs without number
+  // comparison code is used when the number comparison has been inlined, and
+  // the stub will be called if one of the operands is not a number.
+  bool include_number_compare_;
+
+  // Generate the comparison code for two smi operands in the stub.
+  bool include_smi_compare_;
+
+  // Register holding the left hand side of the comparison if the stub gives
+  // a choice, no_reg otherwise.
+
+  Register lhs_;
+  // Register holding the right hand side of the comparison if the stub gives
+  // a choice, no_reg otherwise.
+  Register rhs_;
+
+  // Encoding of the minor key in 16 bits.
+  class StrictField: public BitField<bool, 0, 1> {};
+  class NeverNanNanField: public BitField<bool, 1, 1> {};
+  class IncludeNumberCompareField: public BitField<bool, 2, 1> {};
+  class IncludeSmiCompareField: public  BitField<bool, 3, 1> {};
+  class RegisterField: public BitField<bool, 4, 1> {};
+  class ConditionField: public BitField<int, 5, 11> {};
+
+  Major MajorKey() { return Compare; }
+
+  int MinorKey();
+
+  virtual int GetCodeKind() { return Code::COMPARE_IC; }
+  virtual void FinishCode(Code* code) {
+    code->set_compare_state(CompareIC::GENERIC);
+  }
+
+  // Branch to the label if the given object isn't a symbol.
+  void BranchIfNonSymbol(MacroAssembler* masm,
+                         Label* label,
+                         Register object,
+                         Register scratch);
+
+  // Unfortunately you have to run without snapshots to see most of these
+  // names in the profile since most compare stubs end up in the snapshot.
+  virtual void PrintName(StringStream* stream);
+};
+
+
+class CEntryStub : public CodeStub {
+ public:
+  explicit CEntryStub(int result_size,
+                      SaveFPRegsMode save_doubles = kDontSaveFPRegs)
+      : result_size_(result_size), save_doubles_(save_doubles) { }
+
+  void Generate(MacroAssembler* masm);
+
+  // The version of this stub that doesn't save doubles is generated ahead of
+  // time, so it's OK to call it from other stubs that can't cope with GC during
+  // their code generation.  On machines that always have gp registers (x64) we
+  // can generate both variants ahead of time.
+  virtual bool IsPregenerated();
+  static void GenerateAheadOfTime();
+
+ private:
+  void GenerateCore(MacroAssembler* masm,
+                    Label* throw_normal_exception,
+                    Label* throw_termination_exception,
+                    Label* throw_out_of_memory_exception,
+                    bool do_gc,
+                    bool always_allocate_scope);
+  void GenerateThrowTOS(MacroAssembler* masm);
+  void GenerateThrowUncatchable(MacroAssembler* masm,
+                                UncatchableExceptionType type);
+
+  // Number of pointers/values returned.
+  const int result_size_;
+  SaveFPRegsMode save_doubles_;
+
+  Major MajorKey() { return CEntry; }
+  int MinorKey();
+
+  bool NeedsImmovableCode();
+};
+
+
+class JSEntryStub : public CodeStub {
+ public:
+  JSEntryStub() { }
+
+  void Generate(MacroAssembler* masm) { GenerateBody(masm, false); }
+
+ protected:
+  void GenerateBody(MacroAssembler* masm, bool is_construct);
+
+ private:
+  Major MajorKey() { return JSEntry; }
+  int MinorKey() { return 0; }
+};
+
+
+class JSConstructEntryStub : public JSEntryStub {
+ public:
+  JSConstructEntryStub() { }
+
+  void Generate(MacroAssembler* masm) { GenerateBody(masm, true); }
+
+ private:
+  int MinorKey() { return 1; }
+
+  virtual void PrintName(StringStream* stream) {
+    stream->Add("JSConstructEntryStub");
+  }
+};
+
+
+class ArgumentsAccessStub: public CodeStub {
+ public:
+  enum Type {
+    READ_ELEMENT,
+    NEW_NON_STRICT_FAST,
+    NEW_NON_STRICT_SLOW,
+    NEW_STRICT
+  };
+
+  explicit ArgumentsAccessStub(Type type) : type_(type) { }
+
+ private:
+  Type type_;
+
+  Major MajorKey() { return ArgumentsAccess; }
+  int MinorKey() { return type_; }
+
+  void Generate(MacroAssembler* masm);
+  void GenerateReadElement(MacroAssembler* masm);
+  void GenerateNewStrict(MacroAssembler* masm);
+  void GenerateNewNonStrictFast(MacroAssembler* masm);
+  void GenerateNewNonStrictSlow(MacroAssembler* masm);
+
+  virtual void PrintName(StringStream* stream);
+};
+
+
+class RegExpExecStub: public CodeStub {
+ public:
+  RegExpExecStub() { }
+
+ private:
+  Major MajorKey() { return RegExpExec; }
+  int MinorKey() { return 0; }
+
+  void Generate(MacroAssembler* masm);
+};
+
+
+class RegExpConstructResultStub: public CodeStub {
+ public:
+  RegExpConstructResultStub() { }
+
+ private:
+  Major MajorKey() { return RegExpConstructResult; }
+  int MinorKey() { return 0; }
+
+  void Generate(MacroAssembler* masm);
+};
+
+
+class CallFunctionStub: public CodeStub {
+ public:
+  CallFunctionStub(int argc, CallFunctionFlags flags)
+      : argc_(argc), flags_(flags) { }
+
+  void Generate(MacroAssembler* masm);
+
+  virtual void FinishCode(Code* code);
+
+  static void Clear(Heap* heap, Address address);
+
+  static Object* GetCachedValue(Address address);
+
+  static int ExtractArgcFromMinorKey(int minor_key) {
+    return ArgcBits::decode(minor_key);
+  }
+
+  // The object that indicates an uninitialized cache.
+  static Handle<Object> UninitializedSentinel(Isolate* isolate) {
+    return isolate->factory()->the_hole_value();
+  }
+
+  // A raw version of the uninitialized sentinel that's safe to read during
+  // garbage collection (e.g., for patching the cache).
+  static Object* RawUninitializedSentinel(Heap* heap) {
+    return heap->raw_unchecked_the_hole_value();
+  }
+
+  // The object that indicates a megamorphic state.
+  static Handle<Object> MegamorphicSentinel(Isolate* isolate) {
+    return isolate->factory()->undefined_value();
+  }
+
+ private:
+  int argc_;
+  CallFunctionFlags flags_;
+
+  virtual void PrintName(StringStream* stream);
+
+  // Minor key encoding in 32 bits with Bitfield <Type, shift, size>.
+  class FlagBits: public BitField<CallFunctionFlags, 0, 2> {};
+  class ArgcBits: public BitField<unsigned, 2, 32 - 2> {};
+
+  Major MajorKey() { return CallFunction; }
+  int MinorKey() {
+    // Encode the parameters in a unique 32 bit value.
+    return FlagBits::encode(flags_) | ArgcBits::encode(argc_);
+  }
+
+  bool ReceiverMightBeImplicit() {
+    return (flags_ & RECEIVER_MIGHT_BE_IMPLICIT) != 0;
+  }
+
+  bool RecordCallTarget() {
+    return (flags_ & RECORD_CALL_TARGET) != 0;
+  }
+};
+
+
+enum StringIndexFlags {
+  // Accepts smis or heap numbers.
+  STRING_INDEX_IS_NUMBER,
+
+  // Accepts smis or heap numbers that are valid array indices
+  // (ECMA-262 15.4). Invalid indices are reported as being out of
+  // range.
+  STRING_INDEX_IS_ARRAY_INDEX
+};
+
+
+// Generates code implementing String.prototype.charCodeAt.
+//
+// Only supports the case when the receiver is a string and the index
+// is a number (smi or heap number) that is a valid index into the
+// string. Additional index constraints are specified by the
+// flags. Otherwise, bails out to the provided labels.
+//
+// Register usage: |object| may be changed to another string in a way
+// that doesn't affect charCodeAt/charAt semantics, |index| is
+// preserved, |scratch| and |result| are clobbered.
+class StringCharCodeAtGenerator {
+ public:
+  StringCharCodeAtGenerator(Register object,
+                            Register index,
+                            Register scratch,
+                            Register result,
+                            Label* receiver_not_string,
+                            Label* index_not_number,
+                            Label* index_out_of_range,
+                            StringIndexFlags index_flags)
+      : object_(object),
+        index_(index),
+        scratch_(scratch),
+        result_(result),
+        receiver_not_string_(receiver_not_string),
+        index_not_number_(index_not_number),
+        index_out_of_range_(index_out_of_range),
+        index_flags_(index_flags) {
+    ASSERT(!scratch_.is(object_));
+    ASSERT(!scratch_.is(index_));
+    ASSERT(!scratch_.is(result_));
+    ASSERT(!result_.is(object_));
+    ASSERT(!result_.is(index_));
+  }
+
+  // Generates the fast case code. On the fallthrough path |result|
+  // register contains the result.
+  void GenerateFast(MacroAssembler* masm);
+
+  // Generates the slow case code. Must not be naturally
+  // reachable. Expected to be put after a ret instruction (e.g., in
+  // deferred code). Always jumps back to the fast case.
+  void GenerateSlow(MacroAssembler* masm,
+                    const RuntimeCallHelper& call_helper);
+
+ private:
+  Register object_;
+  Register index_;
+  Register scratch_;
+  Register result_;
+
+  Label* receiver_not_string_;
+  Label* index_not_number_;
+  Label* index_out_of_range_;
+
+  StringIndexFlags index_flags_;
+
+  Label call_runtime_;
+  Label index_not_smi_;
+  Label got_smi_index_;
+  Label exit_;
+
+  DISALLOW_COPY_AND_ASSIGN(StringCharCodeAtGenerator);
+};
+
+
+// Generates code for creating a one-char string from a char code.
+class StringCharFromCodeGenerator {
+ public:
+  StringCharFromCodeGenerator(Register code,
+                              Register result)
+      : code_(code),
+        result_(result) {
+    ASSERT(!code_.is(result_));
+  }
+
+  // Generates the fast case code. On the fallthrough path |result|
+  // register contains the result.
+  void GenerateFast(MacroAssembler* masm);
+
+  // Generates the slow case code. Must not be naturally
+  // reachable. Expected to be put after a ret instruction (e.g., in
+  // deferred code). Always jumps back to the fast case.
+  void GenerateSlow(MacroAssembler* masm,
+                    const RuntimeCallHelper& call_helper);
+
+ private:
+  Register code_;
+  Register result_;
+
+  Label slow_case_;
+  Label exit_;
+
+  DISALLOW_COPY_AND_ASSIGN(StringCharFromCodeGenerator);
+};
+
+
+// Generates code implementing String.prototype.charAt.
+//
+// Only supports the case when the receiver is a string and the index
+// is a number (smi or heap number) that is a valid index into the
+// string. Additional index constraints are specified by the
+// flags. Otherwise, bails out to the provided labels.
+//
+// Register usage: |object| may be changed to another string in a way
+// that doesn't affect charCodeAt/charAt semantics, |index| is
+// preserved, |scratch1|, |scratch2|, and |result| are clobbered.
+class StringCharAtGenerator {
+ public:
+  StringCharAtGenerator(Register object,
+                        Register index,
+                        Register scratch1,
+                        Register scratch2,
+                        Register result,
+                        Label* receiver_not_string,
+                        Label* index_not_number,
+                        Label* index_out_of_range,
+                        StringIndexFlags index_flags)
+      : char_code_at_generator_(object,
+                                index,
+                                scratch1,
+                                scratch2,
+                                receiver_not_string,
+                                index_not_number,
+                                index_out_of_range,
+                                index_flags),
+        char_from_code_generator_(scratch2, result) {}
+
+  // Generates the fast case code. On the fallthrough path |result|
+  // register contains the result.
+  void GenerateFast(MacroAssembler* masm);
+
+  // Generates the slow case code. Must not be naturally
+  // reachable. Expected to be put after a ret instruction (e.g., in
+  // deferred code). Always jumps back to the fast case.
+  void GenerateSlow(MacroAssembler* masm,
+                    const RuntimeCallHelper& call_helper);
+
+ private:
+  StringCharCodeAtGenerator char_code_at_generator_;
+  StringCharFromCodeGenerator char_from_code_generator_;
+
+  DISALLOW_COPY_AND_ASSIGN(StringCharAtGenerator);
+};
+
+
+class AllowStubCallsScope {
+ public:
+  AllowStubCallsScope(MacroAssembler* masm, bool allow)
+       : masm_(masm), previous_allow_(masm->allow_stub_calls()) {
+    masm_->set_allow_stub_calls(allow);
+  }
+  ~AllowStubCallsScope() {
+    masm_->set_allow_stub_calls(previous_allow_);
+  }
+
+ private:
+  MacroAssembler* masm_;
+  bool previous_allow_;
+
+  DISALLOW_COPY_AND_ASSIGN(AllowStubCallsScope);
+};
+
+
+class KeyedLoadElementStub : public CodeStub {
+ public:
+  explicit KeyedLoadElementStub(ElementsKind elements_kind)
+      : elements_kind_(elements_kind)
+  { }
+
+  Major MajorKey() { return KeyedLoadElement; }
+  int MinorKey() { return elements_kind_; }
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  ElementsKind elements_kind_;
+
+  DISALLOW_COPY_AND_ASSIGN(KeyedLoadElementStub);
+};
+
+
+class KeyedStoreElementStub : public CodeStub {
+ public:
+  KeyedStoreElementStub(bool is_js_array,
+                        ElementsKind elements_kind)
+    : is_js_array_(is_js_array),
+    elements_kind_(elements_kind) { }
+
+  Major MajorKey() { return KeyedStoreElement; }
+  int MinorKey() {
+    return (is_js_array_ ? 0 : kElementsKindCount) + elements_kind_;
+  }
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  bool is_js_array_;
+  ElementsKind elements_kind_;
+
+  DISALLOW_COPY_AND_ASSIGN(KeyedStoreElementStub);
+};
+
+
+class ToBooleanStub: public CodeStub {
+ public:
+  enum Type {
+    UNDEFINED,
+    BOOLEAN,
+    NULL_TYPE,
+    SMI,
+    SPEC_OBJECT,
+    STRING,
+    HEAP_NUMBER,
+    NUMBER_OF_TYPES
+  };
+
+  // At most 8 different types can be distinguished, because the Code object
+  // only has room for a single byte to hold a set of these types. :-P
+  STATIC_ASSERT(NUMBER_OF_TYPES <= 8);
+
+  class Types {
+   public:
+    Types() {}
+    explicit Types(byte bits) : set_(bits) {}
+
+    bool IsEmpty() const { return set_.IsEmpty(); }
+    bool Contains(Type type) const { return set_.Contains(type); }
+    void Add(Type type) { set_.Add(type); }
+    byte ToByte() const { return set_.ToIntegral(); }
+    void Print(StringStream* stream) const;
+    void TraceTransition(Types to) const;
+    bool Record(Handle<Object> object);
+    bool NeedsMap() const;
+    bool CanBeUndetectable() const;
+
+   private:
+    EnumSet<Type, byte> set_;
+  };
+
+  static Types no_types() { return Types(); }
+  static Types all_types() { return Types((1 << NUMBER_OF_TYPES) - 1); }
+
+  explicit ToBooleanStub(Register tos, Types types = Types())
+      : tos_(tos), types_(types) { }
+
+  void Generate(MacroAssembler* masm);
+  virtual int GetCodeKind() { return Code::TO_BOOLEAN_IC; }
+  virtual void PrintName(StringStream* stream);
+
+  virtual bool SometimesSetsUpAFrame() { return false; }
+
+ private:
+  Major MajorKey() { return ToBoolean; }
+  int MinorKey() { return (tos_.code() << NUMBER_OF_TYPES) | types_.ToByte(); }
+
+  virtual void FinishCode(Code* code) {
+    code->set_to_boolean_state(types_.ToByte());
+  }
+
+  void CheckOddball(MacroAssembler* masm,
+                    Type type,
+                    Heap::RootListIndex value,
+                    bool result);
+  void GenerateTypeTransition(MacroAssembler* masm);
+
+  Register tos_;
+  Types types_;
+};
+
+
+class ElementsTransitionAndStoreStub : public CodeStub {
+ public:
+  ElementsTransitionAndStoreStub(ElementsKind from,
+                                 ElementsKind to,
+                                 bool is_jsarray,
+                                 StrictModeFlag strict_mode)
+      : from_(from),
+        to_(to),
+        is_jsarray_(is_jsarray),
+        strict_mode_(strict_mode) {}
+
+ private:
+  class FromBits:       public BitField<ElementsKind,    0, 8> {};
+  class ToBits:         public BitField<ElementsKind,    8, 8> {};
+  class IsJSArrayBits:  public BitField<bool,           16, 8> {};
+  class StrictModeBits: public BitField<StrictModeFlag, 24, 8> {};
+
+  Major MajorKey() { return ElementsTransitionAndStore; }
+  int MinorKey() {
+    return FromBits::encode(from_) |
+        ToBits::encode(to_) |
+        IsJSArrayBits::encode(is_jsarray_) |
+        StrictModeBits::encode(strict_mode_);
+  }
+
+  void Generate(MacroAssembler* masm);
+
+  ElementsKind from_;
+  ElementsKind to_;
+  bool is_jsarray_;
+  StrictModeFlag strict_mode_;
+
+  DISALLOW_COPY_AND_ASSIGN(ElementsTransitionAndStoreStub);
+};
+
+} }  // namespace v8::internal
+
+#endif  // V8_CODE_STUBS_H_