v8/src/safepoint-table.h

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// Copyright 2011 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_SAFEPOINT_TABLE_H_
#define V8_SAFEPOINT_TABLE_H_
#include "src/allocation.h"
#include "src/heap/heap.h"
#include "src/v8memory.h"
#include "src/zone.h"
namespace v8 {
namespace internal {
struct Register;
class SafepointEntry BASE_EMBEDDED {
public:
SafepointEntry() : info_(0), bits_(NULL) {}
SafepointEntry(unsigned info, uint8_t* bits) : info_(info), bits_(bits) {
DCHECK(is_valid());
}
bool is_valid() const { return bits_ != NULL; }
bool Equals(const SafepointEntry& other) const {
return info_ == other.info_ && bits_ == other.bits_;
}
void Reset() {
info_ = 0;
bits_ = NULL;
}
int deoptimization_index() const {
DCHECK(is_valid());
return DeoptimizationIndexField::decode(info_);
}
static const int kArgumentsFieldBits = 3;
static const int kSaveDoublesFieldBits = 1;
static const int kDeoptIndexBits =
32 - kArgumentsFieldBits - kSaveDoublesFieldBits;
class DeoptimizationIndexField:
public BitField<int, 0, kDeoptIndexBits> {}; // NOLINT
class ArgumentsField:
public BitField<unsigned,
kDeoptIndexBits,
kArgumentsFieldBits> {}; // NOLINT
class SaveDoublesField:
public BitField<bool,
kDeoptIndexBits + kArgumentsFieldBits,
kSaveDoublesFieldBits> { }; // NOLINT
int argument_count() const {
DCHECK(is_valid());
return ArgumentsField::decode(info_);
}
bool has_doubles() const {
DCHECK(is_valid());
return SaveDoublesField::decode(info_);
}
uint8_t* bits() {
DCHECK(is_valid());
return bits_;
}
bool HasRegisters() const;
bool HasRegisterAt(int reg_index) const;
private:
unsigned info_;
uint8_t* bits_;
};
class SafepointTable BASE_EMBEDDED {
public:
explicit SafepointTable(Code* code);
int size() const {
return kHeaderSize +
(length_ * (kPcAndDeoptimizationIndexSize + entry_size_));
}
unsigned length() const { return length_; }
unsigned entry_size() const { return entry_size_; }
unsigned GetPcOffset(unsigned index) const {
DCHECK(index < length_);
return Memory::uint32_at(GetPcOffsetLocation(index));
}
SafepointEntry GetEntry(unsigned index) const {
DCHECK(index < length_);
unsigned info = Memory::uint32_at(GetInfoLocation(index));
uint8_t* bits = &Memory::uint8_at(entries_ + (index * entry_size_));
return SafepointEntry(info, bits);
}
// Returns the entry for the given pc.
SafepointEntry FindEntry(Address pc) const;
void PrintEntry(unsigned index, std::ostream& os) const; // NOLINT
private:
static const uint8_t kNoRegisters = 0xFF;
static const int kLengthOffset = 0;
static const int kEntrySizeOffset = kLengthOffset + kIntSize;
static const int kHeaderSize = kEntrySizeOffset + kIntSize;
static const int kPcSize = kIntSize;
static const int kDeoptimizationIndexSize = kIntSize;
static const int kPcAndDeoptimizationIndexSize =
kPcSize + kDeoptimizationIndexSize;
Address GetPcOffsetLocation(unsigned index) const {
return pc_and_deoptimization_indexes_ +
(index * kPcAndDeoptimizationIndexSize);
}
Address GetInfoLocation(unsigned index) const {
return GetPcOffsetLocation(index) + kPcSize;
}
static void PrintBits(std::ostream& os, // NOLINT
uint8_t byte, int digits);
DisallowHeapAllocation no_allocation_;
Code* code_;
unsigned length_;
unsigned entry_size_;
Address pc_and_deoptimization_indexes_;
Address entries_;
friend class SafepointTableBuilder;
friend class SafepointEntry;
DISALLOW_COPY_AND_ASSIGN(SafepointTable);
};
class Safepoint BASE_EMBEDDED {
public:
typedef enum {
kSimple = 0,
kWithRegisters = 1 << 0,
kWithDoubles = 1 << 1,
kWithRegistersAndDoubles = kWithRegisters | kWithDoubles
} Kind;
enum DeoptMode {
kNoLazyDeopt,
kLazyDeopt
};
static const int kNoDeoptimizationIndex =
(1 << (SafepointEntry::kDeoptIndexBits)) - 1;
void DefinePointerSlot(int index, Zone* zone) { indexes_->Add(index, zone); }
void DefinePointerRegister(Register reg, Zone* zone);
private:
Safepoint(ZoneList<int>* indexes, ZoneList<int>* registers)
: indexes_(indexes), registers_(registers) {}
ZoneList<int>* indexes_;
ZoneList<int>* registers_;
friend class SafepointTableBuilder;
};
class SafepointTableBuilder BASE_EMBEDDED {
public:
explicit SafepointTableBuilder(Zone* zone)
: deoptimization_info_(32, zone),
deopt_index_list_(32, zone),
indexes_(32, zone),
registers_(32, zone),
emitted_(false),
last_lazy_safepoint_(0),
zone_(zone) { }
// Get the offset of the emitted safepoint table in the code.
unsigned GetCodeOffset() const;
// Define a new safepoint for the current position in the body.
Safepoint DefineSafepoint(Assembler* assembler,
Safepoint::Kind kind,
int arguments,
Safepoint::DeoptMode mode);
// Record deoptimization index for lazy deoptimization for the last
// outstanding safepoints.
void RecordLazyDeoptimizationIndex(int index);
void BumpLastLazySafepointIndex() {
last_lazy_safepoint_ = deopt_index_list_.length();
}
// Emit the safepoint table after the body. The number of bits per
// entry must be enough to hold all the pointer indexes.
void Emit(Assembler* assembler, int bits_per_entry);
private:
struct DeoptimizationInfo {
unsigned pc;
unsigned arguments;
bool has_doubles;
};
uint32_t EncodeExceptPC(const DeoptimizationInfo& info, unsigned index);
ZoneList<DeoptimizationInfo> deoptimization_info_;
ZoneList<unsigned> deopt_index_list_;
ZoneList<ZoneList<int>*> indexes_;
ZoneList<ZoneList<int>*> registers_;
unsigned offset_;
bool emitted_;
int last_lazy_safepoint_;
Zone* zone_;
DISALLOW_COPY_AND_ASSIGN(SafepointTableBuilder);
};
} } // namespace v8::internal
#endif // V8_SAFEPOINT_TABLE_H_