// Copyright 2009 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * 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
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_FRAME_ELEMENT_H_
#define V8_FRAME_ELEMENT_H_
#include "number-info.h"
#include "macro-assembler.h"
namespace v8 {
namespace internal {
// -------------------------------------------------------------------------
// Virtual frame elements
//
// The internal elements of the virtual frames. There are several kinds of
// elements:
// * Invalid: elements that are uninitialized or not actually part
// of the virtual frame. They should not be read.
// * Memory: an element that resides in the actual frame. Its address is
// given by its position in the virtual frame.
// * Register: an element that resides in a register.
// * Constant: an element whose value is known at compile time.
class FrameElement BASE_EMBEDDED {
public:
enum SyncFlag {
NOT_SYNCED,
SYNCED
};
inline NumberInfo::Type number_info() {
// Copied elements do not have number info. Instead
// we have to inspect their backing element in the frame.
ASSERT(!is_copy());
if (!is_constant()) return NumberInfoField::decode(value_);
Handle<Object> value = handle();
if (value->IsSmi()) return NumberInfo::kSmi;
if (value->IsHeapNumber()) return NumberInfo::kHeapNumber;
return NumberInfo::kUnknown;
}
inline void set_number_info(NumberInfo::Type info) {
// Copied elements do not have number info. Instead
// we have to inspect their backing element in the frame.
ASSERT(!is_copy());
value_ = value_ & ~NumberInfoField::mask();
value_ = value_ | NumberInfoField::encode(info);
}
// The default constructor creates an invalid frame element.
FrameElement() {
value_ = TypeField::encode(INVALID)
| CopiedField::encode(false)
| SyncedField::encode(false)
| NumberInfoField::encode(NumberInfo::kUninitialized)
| DataField::encode(0);
}
// Factory function to construct an invalid frame element.
static FrameElement InvalidElement() {
FrameElement result;
return result;
}
// Factory function to construct an in-memory frame element.
static FrameElement MemoryElement(NumberInfo::Type info) {
FrameElement result(MEMORY, no_reg, SYNCED, info);
return result;
}
// Factory function to construct an in-register frame element.
static FrameElement RegisterElement(Register reg,
SyncFlag is_synced,
NumberInfo::Type info) {
return FrameElement(REGISTER, reg, is_synced, info);
}
// Factory function to construct a frame element whose value is known at
// compile time.
static FrameElement ConstantElement(Handle<Object> value,
SyncFlag is_synced) {
FrameElement result(value, is_synced);
return result;
}
// Static indirection table for handles to constants. If a frame
// element represents a constant, the data contains an index into
// this table of handles to the actual constants.
typedef ZoneList<Handle<Object> > ZoneObjectList;
static ZoneObjectList* ConstantList();
// Clear the constants indirection table.
static void ClearConstantList() {
ConstantList()->Clear();
}
bool is_synced() const { return SyncedField::decode(value_); }
void set_sync() {
ASSERT(type() != MEMORY);
value_ = value_ | SyncedField::encode(true);
}
void clear_sync() {
ASSERT(type() != MEMORY);
value_ = value_ & ~SyncedField::mask();
}
bool is_valid() const { return type() != INVALID; }
bool is_memory() const { return type() == MEMORY; }
bool is_register() const { return type() == REGISTER; }
bool is_constant() const { return type() == CONSTANT; }
bool is_copy() const { return type() == COPY; }
bool is_copied() const { return CopiedField::decode(value_); }
void set_copied() { value_ = value_ | CopiedField::encode(true); }
void clear_copied() { value_ = value_ & ~CopiedField::mask(); }
Register reg() const {
ASSERT(is_register());
uint32_t reg = DataField::decode(value_);
Register result;
result.code_ = reg;
return result;
}
Handle<Object> handle() const {
ASSERT(is_constant());
return ConstantList()->at(DataField::decode(value_));
}
int index() const {
ASSERT(is_copy());
return DataField::decode(value_);
}
bool Equals(FrameElement other) {
uint32_t masked_difference = (value_ ^ other.value_) & ~CopiedField::mask();
if (!masked_difference) {
// The elements are equal if they agree exactly except on copied field.
return true;
} else {
// If two constants have the same value, and agree otherwise, return true.
return !(masked_difference & ~DataField::mask()) &&
is_constant() &&
handle().is_identical_to(other.handle());
}
}
// Test if two FrameElements refer to the same memory or register location.
bool SameLocation(FrameElement* other) {
if (type() == other->type()) {
if (value_ == other->value_) return true;
if (is_constant() && handle().is_identical_to(other->handle())) {
return true;
}
}
return false;
}
// Given a pair of non-null frame element pointers, return one of them
// as an entry frame candidate or null if they are incompatible.
FrameElement* Combine(FrameElement* other) {
// If either is invalid, the result is.
if (!is_valid()) return this;
if (!other->is_valid()) return other;
if (!SameLocation(other)) return NULL;
// If either is unsynced, the result is.
FrameElement* result = is_synced() ? other : this;
return result;
}
private:
enum Type {
INVALID,
MEMORY,
REGISTER,
CONSTANT,
COPY
};
// Used to construct memory and register elements.
FrameElement(Type type,
Register reg,
SyncFlag is_synced,
NumberInfo::Type info) {
value_ = TypeField::encode(type)
| CopiedField::encode(false)
| SyncedField::encode(is_synced != NOT_SYNCED)
| NumberInfoField::encode(info)
| DataField::encode(reg.code_ > 0 ? reg.code_ : 0);
}
// Used to construct constant elements.
FrameElement(Handle<Object> value, SyncFlag is_synced) {
value_ = TypeField::encode(CONSTANT)
| CopiedField::encode(false)
| SyncedField::encode(is_synced != NOT_SYNCED)
| NumberInfoField::encode(NumberInfo::kUninitialized)
| DataField::encode(ConstantList()->length());
ConstantList()->Add(value);
}
Type type() const { return TypeField::decode(value_); }
void set_type(Type type) {
value_ = value_ & ~TypeField::mask();
value_ = value_ | TypeField::encode(type);
}
void set_index(int new_index) {
ASSERT(is_copy());
value_ = value_ & ~DataField::mask();
value_ = value_ | DataField::encode(new_index);
}
void set_reg(Register new_reg) {
ASSERT(is_register());
value_ = value_ & ~DataField::mask();
value_ = value_ | DataField::encode(new_reg.code_);
}
// Encode type, copied, synced and data in one 32 bit integer.
uint32_t value_;
class TypeField: public BitField<Type, 0, 3> {};
class CopiedField: public BitField<bool, 3, 1> {};
class SyncedField: public BitField<bool, 4, 1> {};
class NumberInfoField: public BitField<NumberInfo::Type, 5, 3> {};
class DataField: public BitField<uint32_t, 8, 32 - 8> {};
friend class VirtualFrame;
};
} } // namespace v8::internal
#endif // V8_FRAME_ELEMENT_H_