Remove some dead code.

src/register-allocator.h

-// Copyright 2008 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_REGISTER_ALLOCATOR_H_
-#define V8_REGISTER_ALLOCATOR_H_
-
-#include "macro-assembler.h"
-#include "type-info.h"
-
-#if V8_TARGET_ARCH_IA32
-#include "ia32/register-allocator-ia32.h"
-#elif V8_TARGET_ARCH_X64
-#include "x64/register-allocator-x64.h"
-#elif V8_TARGET_ARCH_ARM
-#include "arm/register-allocator-arm.h"
-#elif V8_TARGET_ARCH_MIPS
-#include "mips/register-allocator-mips.h"
-#else
-#error Unsupported target architecture.
-#endif
-
-namespace v8 {
-namespace internal {
-
-
-// -------------------------------------------------------------------------
-// Results
-//
-// Results encapsulate the compile-time values manipulated by the code
-// generator.  They can represent registers or constants.
-
-class Result BASE_EMBEDDED {
- public:
-  enum Type {
-    INVALID,
-    REGISTER,
-    CONSTANT
-  };
-
-  // Construct an invalid result.
-  Result() { invalidate(); }
-
-  // Construct a register Result.
-  explicit Result(Register reg, TypeInfo info = TypeInfo::Unknown());
-
-  // Construct a Result whose value is a compile-time constant.
-  explicit Result(Handle<Object> value) {
-    ZoneObjectList* constant_list = Isolate::Current()->result_constant_list();
-    TypeInfo info = TypeInfo::TypeFromValue(value);
-    value_ = TypeField::encode(CONSTANT)
-        | TypeInfoField::encode(info.ToInt())
-        | IsUntaggedInt32Field::encode(false)
-        | DataField::encode(constant_list->length());
-    constant_list->Add(value);
-  }
-
-  // The copy constructor and assignment operators could each create a new
-  // register reference.
-  inline Result(const Result& other);
-
-  inline Result& operator=(const Result& other);
-
-  inline ~Result();
-
-  inline void Unuse();
-
-  Type type() const { return TypeField::decode(value_); }
-
-  void invalidate() { value_ = TypeField::encode(INVALID); }
-
-  inline TypeInfo type_info() const;
-  inline void set_type_info(TypeInfo info);
-  inline bool is_number() const;
-  inline bool is_smi() const;
-  inline bool is_integer32() const;
-  inline bool is_double() const;
-
-  bool is_valid() const { return type() != INVALID; }
-  bool is_register() const { return type() == REGISTER; }
-  bool is_constant() const { return type() == CONSTANT; }
-
-  // An untagged int32 Result contains a signed int32 in a register
-  // or as a constant.  These are only allowed in a side-effect-free
-  // int32 calculation, and if a non-int32 input shows up or an overflow
-  // occurs, we bail out and drop all the int32 values.  Constants are
-  // not converted to int32 until they are loaded into a register.
-  bool is_untagged_int32() const {
-    return IsUntaggedInt32Field::decode(value_);
-  }
-  void set_untagged_int32(bool value) {
-    value_ &= ~IsUntaggedInt32Field::mask();
-    value_ |= IsUntaggedInt32Field::encode(value);
-  }
-
-  Register reg() const {
-    ASSERT(is_register());
-    uint32_t reg = DataField::decode(value_);
-    Register result;
-    result.code_ = reg;
-    return result;
-  }
-
-  Handle<Object> handle() const {
-    ASSERT(type() == CONSTANT);
-    return Isolate::Current()->result_constant_list()->
-        at(DataField::decode(value_));
-  }
-
-  // Move this result to an arbitrary register.  The register is not
-  // necessarily spilled from the frame or even singly-referenced outside
-  // it.
-  void ToRegister();
-
-  // Move this result to a specified register.  The register is spilled from
-  // the frame, and the register is singly-referenced (by this result)
-  // outside the frame.
-  void ToRegister(Register reg);
-
- private:
-  uint32_t value_;
-
-  // Declare BitFields with template parameters <type, start, size>.
-  class TypeField: public BitField<Type, 0, 2> {};
-  class TypeInfoField : public BitField<int, 2, 6> {};
-  class IsUntaggedInt32Field : public BitField<bool, 8, 1> {};
-  class DataField: public BitField<uint32_t, 9, 32 - 9> {};
-
-  inline void CopyTo(Result* destination) const;
-
-  friend class CodeGeneratorScope;
-};
-
-
-// -------------------------------------------------------------------------
-// Register file
-//
-// The register file tracks reference counts for the processor registers.
-// It is used by both the register allocator and the virtual frame.
-
-class RegisterFile BASE_EMBEDDED {
- public:
-  RegisterFile() { Reset(); }
-
-  void Reset() {
-    for (int i = 0; i < kNumRegisters; i++) {
-      ref_counts_[i] = 0;
-    }
-  }
-
-  // Predicates and accessors for the reference counts.
-  bool is_used(int num) {
-    ASSERT(0 <= num && num < kNumRegisters);
-    return ref_counts_[num] > 0;
-  }
-
-  int count(int num) {
-    ASSERT(0 <= num && num < kNumRegisters);
-    return ref_counts_[num];
-  }
-
-  // Record a use of a register by incrementing its reference count.
-  void Use(int num) {
-    ASSERT(0 <= num && num < kNumRegisters);
-    ref_counts_[num]++;
-  }
-
-  // Record that a register will no longer be used by decrementing its
-  // reference count.
-  void Unuse(int num) {
-    ASSERT(is_used(num));
-    ref_counts_[num]--;
-  }
-
-  // Copy the reference counts from this register file to the other.
-  void CopyTo(RegisterFile* other) {
-    for (int i = 0; i < kNumRegisters; i++) {
-      other->ref_counts_[i] = ref_counts_[i];
-    }
-  }
-
- private:
-  // C++ doesn't like zero length arrays, so we make the array length 1 even if
-  // we don't need it.
-  static const int kNumRegisters =
-      (RegisterAllocatorConstants::kNumRegisters == 0) ?
-      1 : RegisterAllocatorConstants::kNumRegisters;
-
-  int ref_counts_[kNumRegisters];
-
-  // Very fast inlined loop to find a free register.  Used in
-  // RegisterAllocator::AllocateWithoutSpilling.  Returns
-  // kInvalidRegister if no free register found.
-  int ScanForFreeRegister() {
-    for (int i = 0; i < RegisterAllocatorConstants::kNumRegisters; i++) {
-      if (!is_used(i)) return i;
-    }
-    return RegisterAllocatorConstants::kInvalidRegister;
-  }
-
-  friend class RegisterAllocator;
-};
-
-
-// -------------------------------------------------------------------------
-// Register allocator
-//
-
-class RegisterAllocator BASE_EMBEDDED {
- public:
-  static const int kNumRegisters =
-      RegisterAllocatorConstants::kNumRegisters;
-  static const int kInvalidRegister =
-      RegisterAllocatorConstants::kInvalidRegister;
-
-  explicit RegisterAllocator(CodeGenerator* cgen) : cgen_(cgen) {}
-
-  // True if the register is reserved by the code generator, false if it
-  // can be freely used by the allocator Defined in the
-  // platform-specific XXX-inl.h files..
-  static inline bool IsReserved(Register reg);
-
-  // Convert between (unreserved) assembler registers and allocator
-  // numbers.  Defined in the platform-specific XXX-inl.h files.
-  static inline int ToNumber(Register reg);
-  static inline Register ToRegister(int num);
-
-  // Predicates and accessors for the registers' reference counts.
-  bool is_used(int num) { return registers_.is_used(num); }
-  inline bool is_used(Register reg);
-
-  int count(int num) { return registers_.count(num); }
-  inline int count(Register reg);
-
-  // Explicitly record a reference to a register.
-  void Use(int num) { registers_.Use(num); }
-  inline void Use(Register reg);
-
-  // Explicitly record that a register will no longer be used.
-  void Unuse(int num) { registers_.Unuse(num); }
-  inline void Unuse(Register reg);
-
-  // Reset the register reference counts to free all non-reserved registers.
-  void Reset() { registers_.Reset(); }
-
-  // Initialize the register allocator for entry to a JS function.  On
-  // entry, the (non-reserved) registers used by the JS calling
-  // convention are referenced and the other (non-reserved) registers
-  // are free.
-  inline void Initialize();
-
-  // Allocate a free register and return a register result if possible or
-  // fail and return an invalid result.
-  Result Allocate();
-
-  // Allocate a specific register if possible, spilling it from the
-  // current frame if necessary, or else fail and return an invalid
-  // result.
-  Result Allocate(Register target);
-
-  // Allocate a free register without spilling any from the current
-  // frame or fail and return an invalid result.
-  Result AllocateWithoutSpilling();
-
-  // Allocate a free byte register without spilling any from the current
-  // frame or fail and return an invalid result.
-  Result AllocateByteRegisterWithoutSpilling();
-
-  // Copy the internal state to a register file, to be restored later by
-  // RestoreFrom.
-  void SaveTo(RegisterFile* register_file) {
-    registers_.CopyTo(register_file);
-  }
-
-  // Restore the internal state.
-  void RestoreFrom(RegisterFile* register_file) {
-    register_file->CopyTo(&registers_);
-  }
-
- private:
-  CodeGenerator* cgen_;
-  RegisterFile registers_;
-};
-
-} }  // namespace v8::internal
-
-#endif  // V8_REGISTER_ALLOCATOR_H_