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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/assert-scope.h"
#include "src/utils.h"
#include "src/v8memory.h"
#include "src/zone/zone.h"
namespace v8 {
namespace internal {
class Register;
class SafepointEntry BASE_EMBEDDED {
public:
SafepointEntry() : info_(0), bits_(nullptr), trampoline_pc_(-1) {}
SafepointEntry(unsigned info, uint8_t* bits, int trampoline_pc)
: info_(info), bits_(bits), trampoline_pc_(trampoline_pc) {
DCHECK(is_valid());
}
bool is_valid() const { return bits_ != nullptr; }
bool Equals(const SafepointEntry& other) const {
return info_ == other.info_ && bits_ == other.bits_;
}
void Reset() {
info_ = 0;
bits_ = nullptr;
}
int deoptimization_index() const {
DCHECK(is_valid());
return DeoptimizationIndexField::decode(info_);
}
int trampoline_pc() { return trampoline_pc_; }
void set_trampoline_pc(int trampoline_pc) { trampoline_pc_ = trampoline_pc; }
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_;
// It needs to be an integer as it is -1 for eager deoptimizations.
int trampoline_pc_;
};
class SafepointTable BASE_EMBEDDED {
public:
explicit SafepointTable(Code* code);
explicit SafepointTable(Address instruction_start,
size_t safepoint_table_offset, uint32_t stack_slots,
bool has_deopt = false);
int size() const {
return kHeaderSize + (length_ * (kFixedEntrySize + 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));
}
int GetTrampolinePcOffset(unsigned index) const {
DCHECK(index < length_);
return Memory::int_at(GetTrampolineLocation(index));
}
unsigned find_return_pc(unsigned pc_offset);
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_));
int trampoline_pc =
has_deopt_ ? Memory::int_at(GetTrampolineLocation(index)) : -1;
return SafepointEntry(info, bits, trampoline_pc);
}
// 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;
// Layout information
static const int kLengthOffset = 0;
static const int kEntrySizeOffset = kLengthOffset + kIntSize;
static const int kHeaderSize = kEntrySizeOffset + kIntSize;
static const int kPcOffset = 0;
static const int kDeoptimizationIndexOffset = kPcOffset + kIntSize;
static const int kTrampolinePcOffset = kDeoptimizationIndexOffset + kIntSize;
static const int kFixedEntrySize = kTrampolinePcOffset + kIntSize;
Address GetPcOffsetLocation(unsigned index) const {
return pc_and_deoptimization_indexes_ + (index * kFixedEntrySize);
}
// TODO(juliana): rename this to GetDeoptimizationIndexLocation
Address GetInfoLocation(unsigned index) const {
return GetPcOffsetLocation(index) + kDeoptimizationIndexOffset;
}
Address GetTrampolineLocation(unsigned index) const {
return GetPcOffsetLocation(index) + kTrampolinePcOffset;
}
static void PrintBits(std::ostream& os, // NOLINT
uint8_t byte, int digits);
DisallowHeapAllocation no_allocation_;
Address instruction_start_;
uint32_t stack_slots_;
unsigned length_;
unsigned entry_size_;
Address pc_and_deoptimization_indexes_;
Address entries_;
bool has_deopt_;
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>* const indexes_;
ZoneList<int>* const registers_;
friend class SafepointTableBuilder;
};
class SafepointTableBuilder BASE_EMBEDDED {
public:
explicit SafepointTableBuilder(Zone* zone)
: deoptimization_info_(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_ = deoptimization_info_.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);
// Find the Deoptimization Info with pc offset {pc} and update its
// trampoline field. Calling this function ensures that the safepoint
// table contains the trampoline PC (trampoline} that replaced the
// return PC {pc} on the stack.
int UpdateDeoptimizationInfo(int pc, int trampoline, int start);
private:
struct DeoptimizationInfo {
unsigned pc;
unsigned arguments;
bool has_doubles;
int trampoline;
ZoneList<int>* indexes;
ZoneList<int>* registers;
unsigned deopt_index;
DeoptimizationInfo(Zone* zone, unsigned pc, unsigned arguments,
Safepoint::Kind kind)
: pc(pc),
arguments(arguments),
has_doubles(kind & Safepoint::kWithDoubles),
trampoline(-1),
indexes(new (zone) ZoneList<int>(8, zone)),
registers(kind & Safepoint::kWithRegisters
? new (zone) ZoneList<int>(4, zone)
: nullptr),
deopt_index(Safepoint::kNoDeoptimizationIndex) {}
};
uint32_t EncodeExceptPC(const DeoptimizationInfo&);
bool IsIdenticalExceptForPc(const DeoptimizationInfo&,
const DeoptimizationInfo&) const;
// If all entries are identical, replace them by 1 entry with pc = kMaxUInt32.
void RemoveDuplicates();
ZoneList<DeoptimizationInfo> deoptimization_info_;
unsigned offset_;
bool emitted_;
int last_lazy_safepoint_;
Zone* zone_;
DISALLOW_COPY_AND_ASSIGN(SafepointTableBuilder);
};
} // namespace internal
} // namespace v8
#endif // V8_SAFEPOINT_TABLE_H_