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// Copyright 2014 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.
#include "src/base/optional.h"
#include "src/codegen/macro-assembler.h"
#include "src/codegen/safepoint-table.h"
#include "src/codegen/source-position-table.h"
#include "src/compiler/backend/gap-resolver.h"
#include "src/compiler/backend/instruction.h"
#include "src/compiler/backend/unwinding-info-writer.h"
#include "src/compiler/osr.h"
#include "src/deoptimizer/deoptimizer.h"
#include "src/trap-handler/trap-handler.h"
namespace v8 {
namespace internal {
class OptimizedCompilationInfo;
namespace compiler {
// Forward declarations.
class DeoptimizationExit;
class FrameAccessState;
class Linkage;
class OutOfLineCode;
struct BranchInfo {
FlagsCondition condition;
Label* true_label;
Label* false_label;
bool fallthru;
class InstructionOperandIterator {
InstructionOperandIterator(Instruction* instr, size_t pos)
: instr_(instr), pos_(pos) {}
Instruction* instruction() const { return instr_; }
InstructionOperand* Advance() { return instr_->InputAt(pos_++); }
Instruction* instr_;
size_t pos_;
enum class DeoptimizationLiteralKind { kObject, kNumber, kString };
// Either a non-null Handle<Object>, a double or a StringConstantBase.
class DeoptimizationLiteral {
DeoptimizationLiteral() : object_(), number_(0), string_(nullptr) {}
explicit DeoptimizationLiteral(Handle<Object> object)
: kind_(DeoptimizationLiteralKind::kObject), object_(object) {
explicit DeoptimizationLiteral(double number)
: kind_(DeoptimizationLiteralKind::kNumber), number_(number) {}
explicit DeoptimizationLiteral(const StringConstantBase* string)
: kind_(DeoptimizationLiteralKind::kString), string_(string) {}
Handle<Object> object() const { return object_; }
const StringConstantBase* string() const { return string_; }
bool operator==(const DeoptimizationLiteral& other) const {
return kind_ == other.kind_ && object_.equals(other.object_) &&
bit_cast<uint64_t>(number_) == bit_cast<uint64_t>(other.number_) &&
bit_cast<intptr_t>(string_) == bit_cast<intptr_t>(other.string_);
Handle<Object> Reify(Isolate* isolate) const;
DeoptimizationLiteralKind kind() const { return kind_; }
DeoptimizationLiteralKind kind_;
Handle<Object> object_;
double number_ = 0;
const StringConstantBase* string_ = nullptr;
// Generates native code for a sequence of instructions.
class V8_EXPORT_PRIVATE CodeGenerator final : public GapResolver::Assembler {
explicit CodeGenerator(Zone* codegen_zone, Frame* frame, Linkage* linkage,
InstructionSequence* instructions,
OptimizedCompilationInfo* info, Isolate* isolate,
base::Optional<OsrHelper> osr_helper,
int start_source_position,
JumpOptimizationInfo* jump_opt,
PoisoningMitigationLevel poisoning_level,
const AssemblerOptions& options, int32_t builtin_index,
std::unique_ptr<AssemblerBuffer> = {});
// Generate native code. After calling AssembleCode, call FinalizeCode to
// produce the actual code object. If an error occurs during either phase,
// FinalizeCode returns an empty MaybeHandle.
void AssembleCode(); // Does not need to run on main thread.
MaybeHandle<Code> FinalizeCode();
OwnedVector<byte> GetSourcePositionTable();
InstructionSequence* instructions() const { return instructions_; }
FrameAccessState* frame_access_state() const { return frame_access_state_; }
const Frame* frame() const { return frame_access_state_->frame(); }
Isolate* isolate() const { return isolate_; }
Linkage* linkage() const { return linkage_; }
Label* GetLabel(RpoNumber rpo) { return &labels_[rpo.ToSize()]; }
void AddProtectedInstructionLanding(uint32_t instr_offset,
uint32_t landing_offset);
bool wasm_runtime_exception_support() const;
SourcePosition start_source_position() const {
return start_source_position_;
void AssembleSourcePosition(Instruction* instr);
void AssembleSourcePosition(SourcePosition source_position);
// Record a safepoint with the given pointer map.
void RecordSafepoint(ReferenceMap* references,
Safepoint::DeoptMode deopt_mode);
Zone* zone() const { return zone_; }
TurboAssembler* tasm() { return &tasm_; }
SafepointTableBuilder* safepoint_table_builder() { return &safepoints_; }
size_t GetSafepointTableOffset() const { return safepoints_.GetCodeOffset(); }
size_t GetHandlerTableOffset() const { return handler_table_offset_; }
const ZoneVector<int>& block_starts() const { return block_starts_; }
const ZoneVector<int>& instr_starts() const { return instr_starts_; }
static constexpr int kBinarySearchSwitchMinimalCases = 4;
GapResolver* resolver() { return &resolver_; }
SafepointTableBuilder* safepoints() { return &safepoints_; }
OptimizedCompilationInfo* info() const { return info_; }
OsrHelper* osr_helper() { return &(*osr_helper_); }
// Create the FrameAccessState object. The Frame is immutable from here on.
void CreateFrameAccessState(Frame* frame);
// Architecture - specific frame finalization.
void FinishFrame(Frame* frame);
// Checks if {block} will appear directly after {current_block_} when
// assembling code, in which case, a fall-through can be used.
bool IsNextInAssemblyOrder(RpoNumber block) const;
// Check if a heap object can be materialized by loading from a heap root,
// which is cheaper on some platforms than materializing the actual heap
// object constant.
bool IsMaterializableFromRoot(Handle<HeapObject> object,
RootIndex* index_return);
enum CodeGenResult { kSuccess, kTooManyDeoptimizationBailouts };
// Assemble instructions for the specified block.
CodeGenResult AssembleBlock(const InstructionBlock* block);
// Inserts mask update at the beginning of an instruction block if the
// predecessor blocks ends with a masking branch.
void TryInsertBranchPoisoning(const InstructionBlock* block);
// Initializes the masking register in the prologue of a function.
void InitializeSpeculationPoison();
// Reset the masking register during execution of a function.
void ResetSpeculationPoison();
// Generates a mask from the pc passed in {kJavaScriptCallCodeStartRegister}.
void GenerateSpeculationPoisonFromCodeStartRegister();
// Assemble code for the specified instruction.
CodeGenResult AssembleInstruction(Instruction* instr,
const InstructionBlock* block);
void AssembleGaps(Instruction* instr);
// Compute branch info from given instruction. Returns a valid rpo number
// if the branch is redundant, the returned rpo number point to the target
// basic block.
RpoNumber ComputeBranchInfo(BranchInfo* branch, Instruction* instr);
// Returns true if a instruction is a tail call that needs to adjust the stack
// pointer before execution. The stack slot index to the empty slot above the
// adjusted stack pointer is returned in |slot|.
bool GetSlotAboveSPBeforeTailCall(Instruction* instr, int* slot);
// Determines how to call helper stubs depending on the code kind.
StubCallMode DetermineStubCallMode() const;
CodeGenResult AssembleDeoptimizerCall(int deoptimization_id,
SourcePosition pos);
// ===========================================================================
// ============= Architecture-specific code generation methods. ==============
// ===========================================================================
CodeGenResult AssembleArchInstruction(Instruction* instr);
void AssembleArchJump(RpoNumber target);
void AssembleArchBranch(Instruction* instr, BranchInfo* branch);
// Generates special branch for deoptimization condition.
void AssembleArchDeoptBranch(Instruction* instr, BranchInfo* branch);
void AssembleArchBoolean(Instruction* instr, FlagsCondition condition);
void AssembleArchTrap(Instruction* instr, FlagsCondition condition);
void AssembleArchBinarySearchSwitchRange(Register input, RpoNumber def_block,
std::pair<int32_t, Label*>* begin,
std::pair<int32_t, Label*>* end);
void AssembleArchBinarySearchSwitch(Instruction* instr);
void AssembleArchLookupSwitch(Instruction* instr);
void AssembleArchTableSwitch(Instruction* instr);
// Generates code that checks whether the {kJavaScriptCallCodeStartRegister}
// contains the expected pointer to the start of the instruction stream.
void AssembleCodeStartRegisterCheck();
void AssembleBranchPoisoning(FlagsCondition condition, Instruction* instr);
// When entering a code that is marked for deoptimization, rather continuing
// with its execution, we jump to a lazy compiled code. We need to do this
// because this code has already been deoptimized and needs to be unlinked
// from the JS functions referring it.
void BailoutIfDeoptimized();
// Generates code to poison the stack pointer and implicit register arguments
// like the context register and the function register.
void AssembleRegisterArgumentPoisoning();
// Generates an architecture-specific, descriptor-specific prologue
// to set up a stack frame.
void AssembleConstructFrame();
// Generates an architecture-specific, descriptor-specific return sequence
// to tear down a stack frame.
void AssembleReturn(InstructionOperand* pop);
void AssembleDeconstructFrame();
// Generates code to manipulate the stack in preparation for a tail call.
void AssemblePrepareTailCall();
// Generates code to pop current frame if it is an arguments adaptor frame.
void AssemblePopArgumentsAdaptorFrame(Register args_reg, Register scratch1,
Register scratch2, Register scratch3);
enum PushTypeFlag {
kImmediatePush = 0x1,
kRegisterPush = 0x2,
kStackSlotPush = 0x4,
kScalarPush = kRegisterPush | kStackSlotPush
using PushTypeFlags = base::Flags<PushTypeFlag>;
static bool IsValidPush(InstructionOperand source, PushTypeFlags push_type);
// Generate a list moves from an instruction that are candidates to be turned
// into push instructions on platforms that support them. In general, the list
// of push candidates are moves to a set of contiguous destination
// InstructionOperand locations on the stack that don't clobber values that
// are needed for resolve the gap or use values generated by the gap,
// i.e. moves that can be hoisted together before the actual gap and assembled
// together.
static void GetPushCompatibleMoves(Instruction* instr,
PushTypeFlags push_type,
ZoneVector<MoveOperands*>* pushes);
class MoveType {
enum Type {
// Detect what type of move or swap needs to be performed. Note that these
// functions do not take into account the representation (Tagged, FP,
// ...etc).
static Type InferMove(InstructionOperand* source,
InstructionOperand* destination);
static Type InferSwap(InstructionOperand* source,
InstructionOperand* destination);
// Called before a tail call |instr|'s gap moves are assembled and allows
// gap-specific pre-processing, e.g. adjustment of the sp for tail calls that
// need it before gap moves or conversion of certain gap moves into pushes.
void AssembleTailCallBeforeGap(Instruction* instr,
int first_unused_stack_slot);
// Called after a tail call |instr|'s gap moves are assembled and allows
// gap-specific post-processing, e.g. adjustment of the sp for tail calls that
// need it after gap moves.
void AssembleTailCallAfterGap(Instruction* instr,
int first_unused_stack_slot);
void FinishCode();
void MaybeEmitOutOfLineConstantPool();
// ===========================================================================
// ============== Architecture-specific gap resolver methods. ================
// ===========================================================================
// Interface used by the gap resolver to emit moves and swaps.
void AssembleMove(InstructionOperand* source,
InstructionOperand* destination) final;
void AssembleSwap(InstructionOperand* source,
InstructionOperand* destination) final;
// ===========================================================================
// =================== Jump table construction methods. ======================
// ===========================================================================
class JumpTable;
// Adds a jump table that is emitted after the actual code. Returns label
// pointing to the beginning of the table. {targets} is assumed to be static
// or zone allocated.
Label* AddJumpTable(Label** targets, size_t target_count);
// Emits a jump table.
void AssembleJumpTable(Label** targets, size_t target_count);
// ===========================================================================
// ================== Deoptimization table construction. =====================
// ===========================================================================
void RecordCallPosition(Instruction* instr);
Handle<DeoptimizationData> GenerateDeoptimizationData();
int DefineDeoptimizationLiteral(DeoptimizationLiteral literal);
DeoptimizationEntry const& GetDeoptimizationEntry(Instruction* instr,
size_t frame_state_offset);
DeoptimizeKind GetDeoptimizationKind(int deoptimization_id) const;
DeoptimizeReason GetDeoptimizationReason(int deoptimization_id) const;
int BuildTranslation(Instruction* instr, int pc_offset,
size_t frame_state_offset,
OutputFrameStateCombine state_combine);
void BuildTranslationForFrameStateDescriptor(
FrameStateDescriptor* descriptor, InstructionOperandIterator* iter,
Translation* translation, OutputFrameStateCombine state_combine);
void TranslateStateValueDescriptor(StateValueDescriptor* desc,
StateValueList* nested,
Translation* translation,
InstructionOperandIterator* iter);
void TranslateFrameStateDescriptorOperands(FrameStateDescriptor* desc,
InstructionOperandIterator* iter,
Translation* translation);
void AddTranslationForOperand(Translation* translation, Instruction* instr,
InstructionOperand* op, MachineType type);
void MarkLazyDeoptSite();
DeoptimizationExit* AddDeoptimizationExit(Instruction* instr,
size_t frame_state_offset);
// ===========================================================================
class DeoptimizationState final : public ZoneObject {
DeoptimizationState(BailoutId bailout_id, int translation_id, int pc_offset,
DeoptimizeKind kind, DeoptimizeReason reason)
: bailout_id_(bailout_id),
reason_(reason) {}
BailoutId bailout_id() const { return bailout_id_; }
int translation_id() const { return translation_id_; }
int pc_offset() const { return pc_offset_; }
DeoptimizeKind kind() const { return kind_; }
DeoptimizeReason reason() const { return reason_; }
BailoutId bailout_id_;
int translation_id_;
int pc_offset_;
DeoptimizeKind kind_;
DeoptimizeReason reason_;
struct HandlerInfo {
Label* handler;
int pc_offset;
friend class OutOfLineCode;
friend class CodeGeneratorTester;
Zone* zone_;
Isolate* isolate_;
FrameAccessState* frame_access_state_;
Linkage* const linkage_;
InstructionSequence* const instructions_;
UnwindingInfoWriter unwinding_info_writer_;
OptimizedCompilationInfo* const info_;
Label* const labels_;
Label return_label_;
RpoNumber current_block_;
SourcePosition start_source_position_;
SourcePosition current_source_position_;
TurboAssembler tasm_;
GapResolver resolver_;
SafepointTableBuilder safepoints_;
ZoneVector<HandlerInfo> handlers_;
ZoneDeque<DeoptimizationExit*> deoptimization_exits_;
ZoneDeque<DeoptimizationState*> deoptimization_states_;
ZoneDeque<DeoptimizationLiteral> deoptimization_literals_;
size_t inlined_function_count_ = 0;
TranslationBuffer translations_;
int handler_table_offset_ = 0;
int last_lazy_deopt_pc_ = 0;
// kArchCallCFunction could be reached either:
// kArchCallCFunction;
// or:
// kArchSaveCallerRegisters;
// kArchCallCFunction;
// kArchRestoreCallerRegisters;
// The boolean is used to distinguish the two cases. In the latter case, we
// also need to decide if FP registers need to be saved, which is controlled
// by fp_mode_.
bool caller_registers_saved_;
SaveFPRegsMode fp_mode_;
JumpTable* jump_tables_;
OutOfLineCode* ools_;
base::Optional<OsrHelper> osr_helper_;
int osr_pc_offset_;
int optimized_out_literal_id_;
SourcePositionTableBuilder source_position_table_builder_;
ZoneVector<trap_handler::ProtectedInstructionData> protected_instructions_;
CodeGenResult result_;
PoisoningMitigationLevel poisoning_level_;
ZoneVector<int> block_starts_;
ZoneVector<int> instr_starts_;
} // namespace compiler
} // namespace internal
} // namespace v8