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// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/allocation.h"
#include "vm/code_descriptors.h"
#include "vm/compiler/backend/flow_graph_compiler.h"
#include "vm/compiler/backend/locations.h"
#include "vm/deferred_objects.h"
#include "vm/growable_array.h"
#include "vm/object.h"
#include "vm/runtime_entry.h"
#include "vm/stack_frame.h"
#include "vm/thread.h"
namespace dart {
class Location;
class Value;
class MaterializeObjectInstr;
class StackFrame;
class TimelineEvent;
// Holds all data relevant for execution of deoptimization instructions.
// Structure is allocated in C-heap.
class DeoptContext : public MallocAllocated {
enum DestFrameOptions {
kDestIsOriginalFrame, // Replace the original frame with deopt frame.
kDestIsAllocated // Write deopt frame to a buffer.
// If 'deoptimizing_code' is false, only frame is being deoptimized.
DeoptContext(const StackFrame* frame,
const Code& code,
DestFrameOptions dest_options,
fpu_register_t* fpu_registers,
intptr_t* cpu_registers,
bool is_lazy_deopt,
bool deoptimizing_code);
virtual ~DeoptContext();
// Returns the offset of the dest fp from the dest sp. Used in
// runtime code to adjust the stack size before deoptimization.
intptr_t DestStackAdjustment() const;
intptr_t* GetSourceFrameAddressAt(intptr_t index) const {
ASSERT(source_frame_ != NULL);
ASSERT((0 <= index) && (index < source_frame_size_));
// Convert FP relative index to SP relative one.
index = source_frame_size_ - 1 - index;
return &source_frame_[index];
// Returns index in stack slot notation where -1 is the first argument
intptr_t GetStackSlot(intptr_t index) const {
ASSERT((0 <= index) && (index < source_frame_size_));
index -= num_args_;
return index < 0 ? index : index - kDartFrameFixedSize;
intptr_t GetSourceFp() const;
intptr_t GetSourcePp() const;
intptr_t GetSourcePc() const;
intptr_t GetCallerFp() const;
void SetCallerFp(intptr_t callers_fp);
ObjectPtr ObjectAt(intptr_t index) const {
const ObjectPool& object_pool = ObjectPool::Handle(object_pool_);
return object_pool.ObjectAt(index);
intptr_t RegisterValue(Register reg) const {
ASSERT(reg >= 0);
ASSERT(reg < kNumberOfCpuRegisters);
ASSERT(cpu_registers_ != NULL);
return cpu_registers_[reg];
double FpuRegisterValue(FpuRegister reg) const {
ASSERT(fpu_registers_ != NULL);
ASSERT(reg >= 0);
ASSERT(reg < kNumberOfFpuRegisters);
return *reinterpret_cast<double*>(&fpu_registers_[reg]);
simd128_value_t FpuRegisterValueAsSimd128(FpuRegister reg) const {
ASSERT(fpu_registers_ != NULL);
ASSERT(reg >= 0);
ASSERT(reg < kNumberOfFpuRegisters);
const float* address = reinterpret_cast<float*>(&fpu_registers_[reg]);
return simd128_value_t().readFrom(address);
// Return base pointer for the given frame (either source or destination).
// Base pointer points to the slot with the lowest address in the frame
// including incoming arguments and artificial deoptimization frame
// on top of it.
// Note: artificial frame created by the deoptimization stub is considered
// part of the frame because it contains saved caller PC and FP that
// deoptimization will fill in.
intptr_t* FrameBase(const StackFrame* frame) {
// SP of the deoptimization frame is the lowest slot because
// stack is growing downwards.
return reinterpret_cast<intptr_t*>(frame->sp() -
(kDartFrameFixedSize * kWordSize));
void set_dest_frame(const StackFrame* frame) {
ASSERT(frame != NULL && dest_frame_ == NULL);
dest_frame_ = FrameBase(frame);
Thread* thread() const { return thread_; }
Zone* zone() const { return thread_->zone(); }
intptr_t source_frame_size() const { return source_frame_size_; }
intptr_t dest_frame_size() const { return dest_frame_size_; }
CodePtr code() const { return code_; }
bool is_lazy_deopt() const { return is_lazy_deopt_; }
bool deoptimizing_code() const { return deoptimizing_code_; }
ICData::DeoptReasonId deopt_reason() const { return deopt_reason_; }
bool HasDeoptFlag(ICData::DeoptFlags flag) {
return (deopt_flags_ & flag) != 0;
TypedDataPtr deopt_info() const { return deopt_info_; }
// Fills the destination frame but defers materialization of
// objects.
void FillDestFrame();
// Convert deoptimization instructions to a list of moves that need
// to be executed when entering catch entry block from this deoptimization
// point.
const CatchEntryMoves* ToCatchEntryMoves(intptr_t num_vars);
// Materializes all deferred objects. Returns the total number of
// artificial arguments used during deoptimization.
intptr_t MaterializeDeferredObjects();
ArrayPtr DestFrameAsArray();
void VisitObjectPointers(ObjectPointerVisitor* visitor);
void DeferMaterializedObjectRef(intptr_t idx, intptr_t* slot) {
deferred_slots_ = new DeferredObjectRef(
idx, reinterpret_cast<ObjectPtr*>(slot), deferred_slots_);
void DeferMaterialization(double value, DoublePtr* slot) {
deferred_slots_ = new DeferredDouble(
value, reinterpret_cast<ObjectPtr*>(slot), deferred_slots_);
void DeferMintMaterialization(int64_t value, MintPtr* slot) {
deferred_slots_ = new DeferredMint(
value, reinterpret_cast<ObjectPtr*>(slot), deferred_slots_);
void DeferMaterialization(simd128_value_t value, Float32x4Ptr* slot) {
deferred_slots_ = new DeferredFloat32x4(
value, reinterpret_cast<ObjectPtr*>(slot), deferred_slots_);
void DeferMaterialization(simd128_value_t value, Float64x2Ptr* slot) {
deferred_slots_ = new DeferredFloat64x2(
value, reinterpret_cast<ObjectPtr*>(slot), deferred_slots_);
void DeferMaterialization(simd128_value_t value, Int32x4Ptr* slot) {
deferred_slots_ = new DeferredInt32x4(
value, reinterpret_cast<ObjectPtr*>(slot), deferred_slots_);
void DeferRetAddrMaterialization(intptr_t index,
intptr_t deopt_id,
intptr_t* slot) {
deferred_slots_ = new DeferredRetAddr(
index, deopt_id, reinterpret_cast<ObjectPtr*>(slot), deferred_slots_);
void DeferPcMarkerMaterialization(intptr_t index, intptr_t* slot) {
deferred_slots_ = new DeferredPcMarker(
index, reinterpret_cast<ObjectPtr*>(slot), deferred_slots_);
void DeferPpMaterialization(intptr_t index, ObjectPtr* slot) {
deferred_slots_ = new DeferredPp(index, slot, deferred_slots_);
DeferredObject* GetDeferredObject(intptr_t idx) const {
return deferred_objects_[idx];
intptr_t num_args() const { return num_args_; }
intptr_t* GetDestFrameAddressAt(intptr_t index) const {
ASSERT(dest_frame_ != NULL);
ASSERT((0 <= index) && (index < dest_frame_size_));
return &dest_frame_[index];
void PrepareForDeferredMaterialization(intptr_t count) {
if (count > 0) {
deferred_objects_ = new DeferredObject*[count];
deferred_objects_count_ = count;
// Sets the materialized value for some deferred object.
// Claims ownership of the memory for 'object'.
void SetDeferredObjectAt(intptr_t idx, DeferredObject* object) {
deferred_objects_[idx] = object;
intptr_t DeferredObjectsCount() const { return deferred_objects_count_; }
CodePtr code_;
ObjectPoolPtr object_pool_;
TypedDataPtr deopt_info_;
bool dest_frame_is_allocated_;
intptr_t* dest_frame_;
intptr_t dest_frame_size_;
bool source_frame_is_allocated_;
intptr_t* source_frame_;
intptr_t source_frame_size_;
intptr_t* cpu_registers_;
fpu_register_t* fpu_registers_;
intptr_t num_args_;
ICData::DeoptReasonId deopt_reason_;
uint32_t deopt_flags_;
intptr_t caller_fp_;
Thread* thread_;
int64_t deopt_start_micros_;
DeferredSlot* deferred_slots_;
intptr_t deferred_objects_count_;
DeferredObject** deferred_objects_;
const bool is_lazy_deopt_;
const bool deoptimizing_code_;
// Represents one deopt instruction, e.g, setup return address, store object,
// store register, etc. The target is defined by instruction's position in
// the deopt-info array.
class DeoptInstr : public ZoneAllocated {
enum Kind {
// Mints are split into low and high words on 32-bit architectures. Each
// word can be in a register or stack slot. Note Mint pairs are only
// used on 32-bit architectures.
// Mints are held in one word on 64-bit architectures.
static DeoptInstr* Create(intptr_t kind_as_int, intptr_t source_index);
DeoptInstr() {}
virtual ~DeoptInstr() {}
virtual const char* ToCString() const {
const char* args = ArgumentsToCString();
if (args != NULL) {
return Thread::Current()->zone()->PrintToString(
"%s(%s)", KindToCString(kind()), args);
} else {
return KindToCString(kind());
virtual void Execute(DeoptContext* deopt_context, intptr_t* dest_addr) = 0;
virtual CatchEntryMove ToCatchEntryMove(DeoptContext* deopt_context,
intptr_t dest_slot) {
return CatchEntryMove();
virtual DeoptInstr::Kind kind() const = 0;
bool Equals(const DeoptInstr& other) const {
return (kind() == other.kind()) && (source_index() == other.source_index());
// Get the code and return address which is encoded in this
// kRetAfterAddress deopt instruction.
static uword GetRetAddress(DeoptInstr* instr,
const ObjectPool& object_pool,
Code* code);
// Return number of initialized fields in the object that will be
// materialized by kMaterializeObject instruction.
static intptr_t GetFieldCount(DeoptInstr* instr) {
ASSERT(instr->kind() == DeoptInstr::kMaterializeObject);
return instr->source_index();
friend class DeoptInfoBuilder;
virtual intptr_t source_index() const = 0;
virtual const char* ArgumentsToCString() const { return NULL; }
static const char* KindToCString(Kind kind);
// Helper class that allows to read a value of the given register from
// the DeoptContext as the specified type.
// It calls different method depending on which kind of register (cpu/fpu) and
// destination types are specified.
template <typename RegisterType, typename DestinationType>
struct RegisterReader;
template <typename T>
struct RegisterReader<Register, T> {
static intptr_t Read(DeoptContext* context, Register reg) {
return context->RegisterValue(reg);
template <>
struct RegisterReader<FpuRegister, double> {
static double Read(DeoptContext* context, FpuRegister reg) {
return context->FpuRegisterValue(reg);
template <>
struct RegisterReader<FpuRegister, simd128_value_t> {
static simd128_value_t Read(DeoptContext* context, FpuRegister reg) {
return context->FpuRegisterValueAsSimd128(reg);
// Class that encapsulates reading and writing of values that were either in
// the registers in the optimized code or were spilled from those registers
// to the stack.
template <typename RegisterType>
class RegisterSource {
enum Kind {
// Spilled register source represented as its spill slot.
kStackSlot = 0,
// Register source represented as its register index.
kRegister = 1
explicit RegisterSource(intptr_t source_index)
: source_index_(source_index) {}
RegisterSource(Kind kind, intptr_t index)
: source_index_(KindField::encode(kind) |
UntaggedIndexField::encode(index)) {}
template <typename T>
T Value(DeoptContext* context) const {
if (is_register()) {
return static_cast<T>(
RegisterReader<RegisterType, T>::Read(context, reg()));
} else {
return *reinterpret_cast<T*>(
intptr_t StackSlot(DeoptContext* context) const {
return context->GetStackSlot(raw_index());
intptr_t source_index() const { return source_index_; }
const char* ToCString() const {
if (is_register()) {
return Name(reg());
} else {
return Thread::Current()->zone()->PrintToString("s%" Pd "", raw_index());
class KindField : public BitField<intptr_t, intptr_t, 0, 1> {};
class UntaggedIndexField
: public BitField<intptr_t, intptr_t, 1, kBitsPerWord - 1> {};
bool is_register() const {
return KindField::decode(source_index_) == kRegister;
intptr_t raw_index() const {
return UntaggedIndexField::decode(source_index_);
RegisterType reg() const { return static_cast<RegisterType>(raw_index()); }
static const char* Name(Register reg) {
return RegisterNames::RegisterName(reg);
static const char* Name(FpuRegister fpu_reg) {
return RegisterNames::FpuRegisterName(fpu_reg);
const intptr_t source_index_;
typedef RegisterSource<Register> CpuRegisterSource;
typedef RegisterSource<FpuRegister> FpuRegisterSource;
// Builds a deoptimization info table, one DeoptInfo at a time. Call AddXXX
// methods in the order of their target, starting wih deoptimized code
// continuation pc and ending with the first argument of the deoptimized
// code. Call CreateDeoptInfo to write the accumulated instructions into
// the heap and reset the builder's internal state for the next DeoptInfo.
class DeoptInfoBuilder : public ValueObject {
DeoptInfoBuilder(Zone* zone,
const intptr_t num_args,
compiler::Assembler* assembler);
// Return address before instruction.
void AddReturnAddress(const Function& function,
intptr_t deopt_id,
intptr_t dest_index);
// Copy from optimized frame to unoptimized.
void AddCopy(Value* value, const Location& source_loc, intptr_t dest_index);
void AddPcMarker(const Function& function, intptr_t dest_index);
void AddPp(const Function& function, intptr_t dest_index);
void AddCallerFp(intptr_t dest_index);
void AddCallerPp(intptr_t dest_index);
void AddCallerPc(intptr_t dest_index);
// Add object to be materialized. Emit kMaterializeObject instruction.
void AddMaterialization(MaterializeObjectInstr* mat);
// For every materialized object emit instructions describing data required
// for materialization: class of the instance to allocate and field-value
// pairs for initialization.
// Emitted instructions are expected to follow fixed size section of frame
// emitted first. This way they become a part of the bottom-most deoptimized
// frame and are discoverable by GC.
// At deoptimization they will be removed by the stub at the very end:
// after they were used to materialize objects.
// Returns the index of the next stack slot. Used for verification.
intptr_t EmitMaterializationArguments(intptr_t dest_index);
TypedDataPtr CreateDeoptInfo(const Array& deopt_table);
// Mark the actual start of the frame description after all materialization
// instructions were emitted. Used for verification purposes.
void MarkFrameStart() {
ASSERT(frame_start_ == -1);
frame_start_ = instructions_.length();
friend class CompilerDeoptInfo; // For current_info_number_.
class TrieNode;
CpuRegisterSource ToCpuRegisterSource(const Location& loc);
FpuRegisterSource ToFpuRegisterSource(
const Location& loc,
Location::Kind expected_stack_slot_kind);
intptr_t FindOrAddObjectInTable(const Object& obj) const;
intptr_t FindMaterialization(MaterializeObjectInstr* mat) const;
intptr_t CalculateStackIndex(const Location& source_loc) const;
intptr_t FrameSize() const {
ASSERT(frame_start_ != -1);
const intptr_t frame_size = instructions_.length() - frame_start_;
ASSERT(frame_size >= 0);
return frame_size;
void AddConstant(const Object& obj, intptr_t dest_index);
Zone* zone() const { return zone_; }
Zone* zone_;
GrowableArray<DeoptInstr*> instructions_;
const intptr_t num_args_;
compiler::Assembler* assembler_;
// Used to compress entries by sharing suffixes.
TrieNode* trie_root_;
intptr_t current_info_number_;
intptr_t frame_start_;
GrowableArray<MaterializeObjectInstr*> materializations_;
// Utilities for managing the deopt table and its entries. The table is
// stored in an Array in the heap. It consists of triples of (PC offset,
// info, reason). Elements of each entry are stored consecutively in the
// array.
// TODO(vegorov): consider compressing the whole table into a single TypedData
// object.
class DeoptTable : public AllStatic {
// Return the array size in elements for a given number of table entries.
static intptr_t SizeFor(intptr_t length);
// Set the entry at the given index into the table (not an array index).
static void SetEntry(const Array& table,
intptr_t index,
const Smi& offset,
const TypedData& info,
const Smi& reason_and_flags);
// Return the length of the table in entries.
static intptr_t GetLength(const Array& table);
// Set the output parameters (offset, info, reason) to the entry values at
// the index into the table (not an array index).
static void GetEntry(const Array& table,
intptr_t index,
Smi* offset,
TypedData* info,
Smi* reason_and_flags);
static SmiPtr EncodeReasonAndFlags(ICData::DeoptReasonId reason,
uint32_t flags) {
return Smi::New(ReasonField::encode(reason) | FlagsField::encode(flags));
class ReasonField : public BitField<intptr_t, ICData::DeoptReasonId, 0, 8> {};
class FlagsField : public BitField<intptr_t, uint32_t, 8, 8> {};
static const intptr_t kEntrySize = 3;
// Holds deopt information at one deoptimization point. The information consists
// of two parts:
// - first a prefix consisting of kMaterializeObject instructions describing
// objects which had their allocation removed as part of AllocationSinking
// pass and have to be materialized;
// - followed by a list of DeoptInstr objects, specifying transformation
// information for each slot in unoptimized frame(s).
// Arguments for object materialization (class of instance to be allocated and
// field-value pairs) are added as artificial slots to the expression stack
// of the bottom-most frame. They are removed from the stack at the very end
// of deoptimization by the deoptimization stub.
class DeoptInfo : public AllStatic {
// Size of the frame part of the translation not counting kMaterializeObject
// instructions in the prefix.
static intptr_t FrameSize(const TypedData& packed);
// Returns the number of kMaterializeObject instructions in the prefix.
static intptr_t NumMaterializations(const GrowableArray<DeoptInstr*>&);
// Unpack the entire translation into an array of deoptimization
// instructions. This copies any shared suffixes into the array.
static void Unpack(const Array& table,
const TypedData& packed,
GrowableArray<DeoptInstr*>* instructions);
// Size of the frame part of the translation not counting kMaterializeObject
// instructions in the prefix.
static const char* ToCString(const Array& table, const TypedData& packed);
// Returns true iff decompression yields the same instructions as the
// original.
static bool VerifyDecompression(const GrowableArray<DeoptInstr*>& original,
const Array& deopt_table,
const TypedData& packed);
static void UnpackInto(const Array& table,
const TypedData& packed,
GrowableArray<DeoptInstr*>* instructions,
intptr_t length);
} // namespace dart
#endif // !defined(DART_PRECOMPILED_RUNTIME)