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* Copyright (C) 2014 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <algorithm>
#include <array>
#include <type_traits>
#include "base/arena_bit_vector.h"
#include "base/arena_containers.h"
#include "base/arena_object.h"
#include "base/array_ref.h"
#include "base/iteration_range.h"
#include "base/mutex.h"
#include "base/quasi_atomic.h"
#include "base/stl_util.h"
#include "base/transform_array_ref.h"
#include "art_method.h"
#include "data_type.h"
#include "deoptimization_kind.h"
#include "dex/dex_file.h"
#include "dex/dex_file_types.h"
#include "dex/invoke_type.h"
#include "dex/method_reference.h"
#include "entrypoints/quick/quick_entrypoints_enum.h"
#include "handle.h"
#include "handle_scope.h"
#include "intrinsics_enum.h"
#include "locations.h"
#include "mirror/class.h"
#include "mirror/method_type.h"
#include "offsets.h"
#include "utils/intrusive_forward_list.h"
namespace art {
class ArenaStack;
class GraphChecker;
class HBasicBlock;
class HConstructorFence;
class HCurrentMethod;
class HDoubleConstant;
class HEnvironment;
class HFloatConstant;
class HGraphBuilder;
class HGraphVisitor;
class HInstruction;
class HIntConstant;
class HInvoke;
class HLongConstant;
class HNullConstant;
class HParameterValue;
class HPhi;
class HSuspendCheck;
class HTryBoundary;
class LiveInterval;
class LocationSummary;
class SlowPathCode;
class SsaBuilder;
namespace mirror {
class DexCache;
} // namespace mirror
static const int kDefaultNumberOfBlocks = 8;
static const int kDefaultNumberOfSuccessors = 2;
static const int kDefaultNumberOfPredecessors = 2;
static const int kDefaultNumberOfExceptionalPredecessors = 0;
static const int kDefaultNumberOfDominatedBlocks = 1;
static const int kDefaultNumberOfBackEdges = 1;
// The maximum (meaningful) distance (31) that can be used in an integer shift/rotate operation.
static constexpr int32_t kMaxIntShiftDistance = 0x1f;
// The maximum (meaningful) distance (63) that can be used in a long shift/rotate operation.
static constexpr int32_t kMaxLongShiftDistance = 0x3f;
static constexpr uint32_t kUnknownFieldIndex = static_cast<uint32_t>(-1);
static constexpr uint16_t kUnknownClassDefIndex = static_cast<uint16_t>(-1);
static constexpr InvokeType kInvalidInvokeType = static_cast<InvokeType>(-1);
static constexpr uint32_t kNoDexPc = -1;
inline bool IsSameDexFile(const DexFile& lhs, const DexFile& rhs) {
// For the purposes of the compiler, the dex files must actually be the same object
// if we want to safely treat them as the same. This is especially important for JIT
// as custom class loaders can open the same underlying file (or memory) multiple
// times and provide different class resolution but no two class loaders should ever
// use the same DexFile object - doing so is an unsupported hack that can lead to
// all sorts of weird failures.
return &lhs == &rhs;
enum IfCondition {
// All types.
kCondEQ, // ==
kCondNE, // !=
// Signed integers and floating-point numbers.
kCondLT, // <
kCondLE, // <=
kCondGT, // >
kCondGE, // >=
// Unsigned integers.
kCondB, // <
kCondBE, // <=
kCondA, // >
kCondAE, // >=
// First and last aliases.
kCondFirst = kCondEQ,
kCondLast = kCondAE,
enum GraphAnalysisResult {
template <typename T>
static inline typename std::make_unsigned<T>::type MakeUnsigned(T x) {
return static_cast<typename std::make_unsigned<T>::type>(x);
class HInstructionList : public ValueObject {
HInstructionList() : first_instruction_(nullptr), last_instruction_(nullptr) {}
void AddInstruction(HInstruction* instruction);
void RemoveInstruction(HInstruction* instruction);
// Insert `instruction` before/after an existing instruction `cursor`.
void InsertInstructionBefore(HInstruction* instruction, HInstruction* cursor);
void InsertInstructionAfter(HInstruction* instruction, HInstruction* cursor);
// Return true if this list contains `instruction`.
bool Contains(HInstruction* instruction) const;
// Return true if `instruction1` is found before `instruction2` in
// this instruction list and false otherwise. Abort if none
// of these instructions is found.
bool FoundBefore(const HInstruction* instruction1,
const HInstruction* instruction2) const;
bool IsEmpty() const { return first_instruction_ == nullptr; }
void Clear() { first_instruction_ = last_instruction_ = nullptr; }
// Update the block of all instructions to be `block`.
void SetBlockOfInstructions(HBasicBlock* block) const;
void AddAfter(HInstruction* cursor, const HInstructionList& instruction_list);
void AddBefore(HInstruction* cursor, const HInstructionList& instruction_list);
void Add(const HInstructionList& instruction_list);
// Return the number of instructions in the list. This is an expensive operation.
size_t CountSize() const;
HInstruction* first_instruction_;
HInstruction* last_instruction_;
friend class HBasicBlock;
friend class HGraph;
friend class HInstruction;
friend class HInstructionIterator;
friend class HInstructionIteratorHandleChanges;
friend class HBackwardInstructionIterator;
class ReferenceTypeInfo : ValueObject {
typedef Handle<mirror::Class> TypeHandle;
static ReferenceTypeInfo Create(TypeHandle type_handle, bool is_exact);
static ReferenceTypeInfo Create(TypeHandle type_handle) REQUIRES_SHARED(Locks::mutator_lock_) {
return Create(type_handle, type_handle->CannotBeAssignedFromOtherTypes());
static ReferenceTypeInfo CreateUnchecked(TypeHandle type_handle, bool is_exact) {
return ReferenceTypeInfo(type_handle, is_exact);
static ReferenceTypeInfo CreateInvalid() { return ReferenceTypeInfo(); }
static bool IsValidHandle(TypeHandle handle) {
return handle.GetReference() != nullptr;
bool IsValid() const {
return IsValidHandle(type_handle_);
bool IsExact() const { return is_exact_; }
bool IsObjectClass() const REQUIRES_SHARED(Locks::mutator_lock_) {
return GetTypeHandle()->IsObjectClass();
bool IsStringClass() const REQUIRES_SHARED(Locks::mutator_lock_) {
return GetTypeHandle()->IsStringClass();
bool IsObjectArray() const REQUIRES_SHARED(Locks::mutator_lock_) {
return IsArrayClass() && GetTypeHandle()->GetComponentType()->IsObjectClass();
bool IsInterface() const REQUIRES_SHARED(Locks::mutator_lock_) {
return GetTypeHandle()->IsInterface();
bool IsArrayClass() const REQUIRES_SHARED(Locks::mutator_lock_) {
return GetTypeHandle()->IsArrayClass();
bool IsPrimitiveArrayClass() const REQUIRES_SHARED(Locks::mutator_lock_) {
return GetTypeHandle()->IsPrimitiveArray();
bool IsNonPrimitiveArrayClass() const REQUIRES_SHARED(Locks::mutator_lock_) {
return GetTypeHandle()->IsArrayClass() && !GetTypeHandle()->IsPrimitiveArray();
bool CanArrayHold(ReferenceTypeInfo rti) const REQUIRES_SHARED(Locks::mutator_lock_) {
if (!IsExact()) return false;
if (!IsArrayClass()) return false;
return GetTypeHandle()->GetComponentType()->IsAssignableFrom(rti.GetTypeHandle().Get());
bool CanArrayHoldValuesOf(ReferenceTypeInfo rti) const REQUIRES_SHARED(Locks::mutator_lock_) {
if (!IsExact()) return false;
if (!IsArrayClass()) return false;
if (!rti.IsArrayClass()) return false;
return GetTypeHandle()->GetComponentType()->IsAssignableFrom(
Handle<mirror::Class> GetTypeHandle() const { return type_handle_; }
bool IsSupertypeOf(ReferenceTypeInfo rti) const REQUIRES_SHARED(Locks::mutator_lock_) {
return GetTypeHandle()->IsAssignableFrom(rti.GetTypeHandle().Get());
bool IsStrictSupertypeOf(ReferenceTypeInfo rti) const REQUIRES_SHARED(Locks::mutator_lock_) {
return GetTypeHandle().Get() != rti.GetTypeHandle().Get() &&
// Returns true if the type information provide the same amount of details.
// Note that it does not mean that the instructions have the same actual type
// (because the type can be the result of a merge).
bool IsEqual(ReferenceTypeInfo rti) const REQUIRES_SHARED(Locks::mutator_lock_) {
if (!IsValid() && !rti.IsValid()) {
// Invalid types are equal.
return true;
if (!IsValid() || !rti.IsValid()) {
// One is valid, the other not.
return false;
return IsExact() == rti.IsExact()
&& GetTypeHandle().Get() == rti.GetTypeHandle().Get();
ReferenceTypeInfo() : type_handle_(TypeHandle()), is_exact_(false) {}
ReferenceTypeInfo(TypeHandle type_handle, bool is_exact)
: type_handle_(type_handle), is_exact_(is_exact) { }
// The class of the object.
TypeHandle type_handle_;
// Whether or not the type is exact or a superclass of the actual type.
// Whether or not we have any information about this type.
bool is_exact_;
std::ostream& operator<<(std::ostream& os, const ReferenceTypeInfo& rhs);
// Control-flow graph of a method. Contains a list of basic blocks.
class HGraph : public ArenaObject<kArenaAllocGraph> {
HGraph(ArenaAllocator* allocator,
ArenaStack* arena_stack,
const DexFile& dex_file,
uint32_t method_idx,
InstructionSet instruction_set,
InvokeType invoke_type = kInvalidInvokeType,
bool debuggable = false,
bool osr = false,
int start_instruction_id = 0)
: allocator_(allocator),
cached_int_constants_(std::less<int32_t>(), allocator->Adapter(kArenaAllocConstantsMap)),
cached_float_constants_(std::less<int32_t>(), allocator->Adapter(kArenaAllocConstantsMap)),
cached_long_constants_(std::less<int64_t>(), allocator->Adapter(kArenaAllocConstantsMap)),
cached_double_constants_(std::less<int64_t>(), allocator->Adapter(kArenaAllocConstantsMap)),
cha_single_implementation_list_(allocator->Adapter(kArenaAllocCHA)) {
// Acquires and stores RTI of inexact Object to be used when creating HNullConstant.
void InitializeInexactObjectRTI(VariableSizedHandleScope* handles);
ArenaAllocator* GetAllocator() const { return allocator_; }
ArenaStack* GetArenaStack() const { return arena_stack_; }
const ArenaVector<HBasicBlock*>& GetBlocks() const { return blocks_; }
bool IsInSsaForm() const { return in_ssa_form_; }
void SetInSsaForm() { in_ssa_form_ = true; }
HBasicBlock* GetEntryBlock() const { return entry_block_; }
HBasicBlock* GetExitBlock() const { return exit_block_; }
bool HasExitBlock() const { return exit_block_ != nullptr; }
void SetEntryBlock(HBasicBlock* block) { entry_block_ = block; }
void SetExitBlock(HBasicBlock* block) { exit_block_ = block; }
void AddBlock(HBasicBlock* block);
void ComputeDominanceInformation();
void ClearDominanceInformation();
void ClearLoopInformation();
void FindBackEdges(ArenaBitVector* visited);
GraphAnalysisResult BuildDominatorTree();
void SimplifyCFG();
void SimplifyCatchBlocks();
// Analyze all natural loops in this graph. Returns a code specifying that it
// was successful or the reason for failure. The method will fail if a loop
// is a throw-catch loop, i.e. the header is a catch block.
GraphAnalysisResult AnalyzeLoops() const;
// Iterate over blocks to compute try block membership. Needs reverse post
// order and loop information.
void ComputeTryBlockInformation();
// Inline this graph in `outer_graph`, replacing the given `invoke` instruction.
// Returns the instruction to replace the invoke expression or null if the
// invoke is for a void method. Note that the caller is responsible for replacing
// and removing the invoke instruction.
HInstruction* InlineInto(HGraph* outer_graph, HInvoke* invoke);
// Update the loop and try membership of `block`, which was spawned from `reference`.
// In case `reference` is a back edge, `replace_if_back_edge` notifies whether `block`
// should be the new back edge.
void UpdateLoopAndTryInformationOfNewBlock(HBasicBlock* block,
HBasicBlock* reference,
bool replace_if_back_edge);
// Need to add a couple of blocks to test if the loop body is entered and
// put deoptimization instructions, etc.
void TransformLoopHeaderForBCE(HBasicBlock* header);
// Adds a new loop directly after the loop with the given header and exit.
// Returns the new preheader.
HBasicBlock* TransformLoopForVectorization(HBasicBlock* header,
HBasicBlock* body,
HBasicBlock* exit);
// Removes `block` from the graph. Assumes `block` has been disconnected from
// other blocks and has no instructions or phis.
void DeleteDeadEmptyBlock(HBasicBlock* block);
// Splits the edge between `block` and `successor` while preserving the
// indices in the predecessor/successor lists. If there are multiple edges
// between the blocks, the lowest indices are used.
// Returns the new block which is empty and has the same dex pc as `successor`.
HBasicBlock* SplitEdge(HBasicBlock* block, HBasicBlock* successor);
void SplitCriticalEdge(HBasicBlock* block, HBasicBlock* successor);
void OrderLoopHeaderPredecessors(HBasicBlock* header);
// Transform a loop into a format with a single preheader.
// Each phi in the header should be split: original one in the header should only hold
// inputs reachable from the back edges and a single input from the preheader. The newly created
// phi in the preheader should collate the inputs from the original multiple incoming blocks.
// Loops in the graph typically have a single preheader, so this method is used to "repair" loops
// that no longer have this property.
void TransformLoopToSinglePreheaderFormat(HBasicBlock* header);
void SimplifyLoop(HBasicBlock* header);
int32_t GetNextInstructionId() {
CHECK_NE(current_instruction_id_, INT32_MAX);
return current_instruction_id_++;
int32_t GetCurrentInstructionId() const {
return current_instruction_id_;
void SetCurrentInstructionId(int32_t id) {
CHECK_GE(id, current_instruction_id_);
current_instruction_id_ = id;
uint16_t GetMaximumNumberOfOutVRegs() const {
return maximum_number_of_out_vregs_;
void SetMaximumNumberOfOutVRegs(uint16_t new_value) {
maximum_number_of_out_vregs_ = new_value;
void UpdateMaximumNumberOfOutVRegs(uint16_t other_value) {
maximum_number_of_out_vregs_ = std::max(maximum_number_of_out_vregs_, other_value);
void UpdateTemporariesVRegSlots(size_t slots) {
temporaries_vreg_slots_ = std::max(slots, temporaries_vreg_slots_);
size_t GetTemporariesVRegSlots() const {
return temporaries_vreg_slots_;
void SetNumberOfVRegs(uint16_t number_of_vregs) {
number_of_vregs_ = number_of_vregs;
uint16_t GetNumberOfVRegs() const {
return number_of_vregs_;
void SetNumberOfInVRegs(uint16_t value) {
number_of_in_vregs_ = value;
uint16_t GetNumberOfInVRegs() const {
return number_of_in_vregs_;
uint16_t GetNumberOfLocalVRegs() const {
return number_of_vregs_ - number_of_in_vregs_;
const ArenaVector<HBasicBlock*>& GetReversePostOrder() const {
return reverse_post_order_;
ArrayRef<HBasicBlock* const> GetReversePostOrderSkipEntryBlock() {
DCHECK(GetReversePostOrder()[0] == entry_block_);
return ArrayRef<HBasicBlock* const>(GetReversePostOrder()).SubArray(1);
IterationRange<ArenaVector<HBasicBlock*>::const_reverse_iterator> GetPostOrder() const {
return ReverseRange(GetReversePostOrder());
const ArenaVector<HBasicBlock*>& GetLinearOrder() const {
return linear_order_;
IterationRange<ArenaVector<HBasicBlock*>::const_reverse_iterator> GetLinearPostOrder() const {
return ReverseRange(GetLinearOrder());
bool HasBoundsChecks() const {
return has_bounds_checks_;
void SetHasBoundsChecks(bool value) {
has_bounds_checks_ = value;
bool IsDebuggable() const { return debuggable_; }
// Returns a constant of the given type and value. If it does not exist
// already, it is created and inserted into the graph. This method is only for
// integral types.
HConstant* GetConstant(DataType::Type type, int64_t value, uint32_t dex_pc = kNoDexPc);
// TODO: This is problematic for the consistency of reference type propagation
// because it can be created anytime after the pass and thus it will be left
// with an invalid type.
HNullConstant* GetNullConstant(uint32_t dex_pc = kNoDexPc);
HIntConstant* GetIntConstant(int32_t value, uint32_t dex_pc = kNoDexPc) {
return CreateConstant(value, &cached_int_constants_, dex_pc);
HLongConstant* GetLongConstant(int64_t value, uint32_t dex_pc = kNoDexPc) {
return CreateConstant(value, &cached_long_constants_, dex_pc);
HFloatConstant* GetFloatConstant(float value, uint32_t dex_pc = kNoDexPc) {
return CreateConstant(bit_cast<int32_t, float>(value), &cached_float_constants_, dex_pc);
HDoubleConstant* GetDoubleConstant(double value, uint32_t dex_pc = kNoDexPc) {
return CreateConstant(bit_cast<int64_t, double>(value), &cached_double_constants_, dex_pc);
HCurrentMethod* GetCurrentMethod();
const DexFile& GetDexFile() const {
return dex_file_;
uint32_t GetMethodIdx() const {
return method_idx_;
// Get the method name (without the signature), e.g. "<init>"
const char* GetMethodName() const;
// Get the pretty method name (class + name + optionally signature).
std::string PrettyMethod(bool with_signature = true) const;
InvokeType GetInvokeType() const {
return invoke_type_;
InstructionSet GetInstructionSet() const {
return instruction_set_;
bool IsCompilingOsr() const { return osr_; }
ArenaSet<ArtMethod*>& GetCHASingleImplementationList() {
return cha_single_implementation_list_;
void AddCHASingleImplementationDependency(ArtMethod* method) {
bool HasShouldDeoptimizeFlag() const {
return number_of_cha_guards_ != 0;
bool HasTryCatch() const { return has_try_catch_; }
void SetHasTryCatch(bool value) { has_try_catch_ = value; }
bool HasSIMD() const { return has_simd_; }
void SetHasSIMD(bool value) { has_simd_ = value; }
bool HasLoops() const { return has_loops_; }
void SetHasLoops(bool value) { has_loops_ = value; }
bool HasIrreducibleLoops() const { return has_irreducible_loops_; }
void SetHasIrreducibleLoops(bool value) { has_irreducible_loops_ = value; }
ArtMethod* GetArtMethod() const { return art_method_; }
void SetArtMethod(ArtMethod* method) { art_method_ = method; }
// Returns an instruction with the opposite Boolean value from 'cond'.
// The instruction has been inserted into the graph, either as a constant, or
// before cursor.
HInstruction* InsertOppositeCondition(HInstruction* cond, HInstruction* cursor);
ReferenceTypeInfo GetInexactObjectRti() const { return inexact_object_rti_; }
uint32_t GetNumberOfCHAGuards() { return number_of_cha_guards_; }
void SetNumberOfCHAGuards(uint32_t num) { number_of_cha_guards_ = num; }
void IncrementNumberOfCHAGuards() { number_of_cha_guards_++; }
void RemoveInstructionsAsUsersFromDeadBlocks(const ArenaBitVector& visited) const;
void RemoveDeadBlocks(const ArenaBitVector& visited);
template <class InstructionType, typename ValueType>
InstructionType* CreateConstant(ValueType value,
ArenaSafeMap<ValueType, InstructionType*>* cache,
uint32_t dex_pc = kNoDexPc) {
// Try to find an existing constant of the given value.
InstructionType* constant = nullptr;
auto cached_constant = cache->find(value);
if (cached_constant != cache->end()) {
constant = cached_constant->second;
// If not found or previously deleted, create and cache a new instruction.
// Don't bother reviving a previously deleted instruction, for simplicity.
if (constant == nullptr || constant->GetBlock() == nullptr) {
constant = new (allocator_) InstructionType(value, dex_pc);
cache->Overwrite(value, constant);
return constant;
void InsertConstant(HConstant* instruction);
// Cache a float constant into the graph. This method should only be
// called by the SsaBuilder when creating "equivalent" instructions.
void CacheFloatConstant(HFloatConstant* constant);
// See CacheFloatConstant comment.
void CacheDoubleConstant(HDoubleConstant* constant);
ArenaAllocator* const allocator_;
ArenaStack* const arena_stack_;
// List of blocks in insertion order.
ArenaVector<HBasicBlock*> blocks_;
// List of blocks to perform a reverse post order tree traversal.
ArenaVector<HBasicBlock*> reverse_post_order_;
// List of blocks to perform a linear order tree traversal. Unlike the reverse
// post order, this order is not incrementally kept up-to-date.
ArenaVector<HBasicBlock*> linear_order_;
HBasicBlock* entry_block_;
HBasicBlock* exit_block_;
// The maximum number of virtual registers arguments passed to a HInvoke in this graph.
uint16_t maximum_number_of_out_vregs_;
// The number of virtual registers in this method. Contains the parameters.
uint16_t number_of_vregs_;
// The number of virtual registers used by parameters of this method.
uint16_t number_of_in_vregs_;
// Number of vreg size slots that the temporaries use (used in baseline compiler).
size_t temporaries_vreg_slots_;
// Flag whether there are bounds checks in the graph. We can skip
// BCE if it's false. It's only best effort to keep it up to date in
// the presence of code elimination so there might be false positives.
bool has_bounds_checks_;
// Flag whether there are try/catch blocks in the graph. We will skip
// try/catch-related passes if it's false. It's only best effort to keep
// it up to date in the presence of code elimination so there might be
// false positives.
bool has_try_catch_;
// Flag whether SIMD instructions appear in the graph. If true, the
// code generators may have to be more careful spilling the wider
// contents of SIMD registers.
bool has_simd_;
// Flag whether there are any loops in the graph. We can skip loop
// optimization if it's false. It's only best effort to keep it up
// to date in the presence of code elimination so there might be false
// positives.
bool has_loops_;
// Flag whether there are any irreducible loops in the graph. It's only
// best effort to keep it up to date in the presence of code elimination
// so there might be false positives.
bool has_irreducible_loops_;
// Indicates whether the graph should be compiled in a way that
// ensures full debuggability. If false, we can apply more
// aggressive optimizations that may limit the level of debugging.
const bool debuggable_;
// The current id to assign to a newly added instruction. See HInstruction.id_.
int32_t current_instruction_id_;
// The dex file from which the method is from.
const DexFile& dex_file_;
// The method index in the dex file.
const uint32_t method_idx_;
// If inlined, this encodes how the callee is being invoked.
const InvokeType invoke_type_;
// Whether the graph has been transformed to SSA form. Only used
// in debug mode to ensure we are not using properties only valid
// for non-SSA form (like the number of temporaries).
bool in_ssa_form_;
// Number of CHA guards in the graph. Used to short-circuit the
// CHA guard optimization pass when there is no CHA guard left.
uint32_t number_of_cha_guards_;
const InstructionSet instruction_set_;
// Cached constants.
HNullConstant* cached_null_constant_;
ArenaSafeMap<int32_t, HIntConstant*> cached_int_constants_;
ArenaSafeMap<int32_t, HFloatConstant*> cached_float_constants_;
ArenaSafeMap<int64_t, HLongConstant*> cached_long_constants_;
ArenaSafeMap<int64_t, HDoubleConstant*> cached_double_constants_;
HCurrentMethod* cached_current_method_;
// The ArtMethod this graph is for. Note that for AOT, it may be null,
// for example for methods whose declaring class could not be resolved
// (such as when the superclass could not be found).
ArtMethod* art_method_;
// Keep the RTI of inexact Object to avoid having to pass stack handle
// collection pointer to passes which may create NullConstant.
ReferenceTypeInfo inexact_object_rti_;
// Whether we are compiling this graph for on stack replacement: this will
// make all loops seen as irreducible and emit special stack maps to mark
// compiled code entries which the interpreter can directly jump to.
const bool osr_;
// List of methods that are assumed to have single implementation.
ArenaSet<ArtMethod*> cha_single_implementation_list_;
friend class SsaBuilder; // For caching constants.
friend class SsaLivenessAnalysis; // For the linear order.
friend class HInliner; // For the reverse post order.
ART_FRIEND_TEST(GraphTest, IfSuccessorSimpleJoinBlock1);
class HLoopInformation : public ArenaObject<kArenaAllocLoopInfo> {
HLoopInformation(HBasicBlock* header, HGraph* graph)
: header_(header),
// Make bit vector growable, as the number of blocks may change.
kArenaAllocLoopInfoBackEdges) {
bool IsIrreducible() const { return irreducible_; }
bool ContainsIrreducibleLoop() const { return contains_irreducible_loop_; }
void Dump(std::ostream& os);
HBasicBlock* GetHeader() const {
return header_;
void SetHeader(HBasicBlock* block) {
header_ = block;
HSuspendCheck* GetSuspendCheck() const { return suspend_check_; }
void SetSuspendCheck(HSuspendCheck* check) { suspend_check_ = check; }
bool HasSuspendCheck() const { return suspend_check_ != nullptr; }
void AddBackEdge(HBasicBlock* back_edge) {
void RemoveBackEdge(HBasicBlock* back_edge) {
RemoveElement(back_edges_, back_edge);
bool IsBackEdge(const HBasicBlock& block) const {
return ContainsElement(back_edges_, &block);
size_t NumberOfBackEdges() const {
return back_edges_.size();
HBasicBlock* GetPreHeader() const;
const ArenaVector<HBasicBlock*>& GetBackEdges() const {
return back_edges_;
// Returns the lifetime position of the back edge that has the
// greatest lifetime position.
size_t GetLifetimeEnd() const;
void ReplaceBackEdge(HBasicBlock* existing, HBasicBlock* new_back_edge) {
ReplaceElement(back_edges_, existing, new_back_edge);
// Finds blocks that are part of this loop.
void Populate();
// Updates blocks population of the loop and all of its outer' ones recursively after the
// population of the inner loop is updated.
void PopulateInnerLoopUpwards(HLoopInformation* inner_loop);
// Returns whether this loop information contains `block`.
// Note that this loop information *must* be populated before entering this function.
bool Contains(const HBasicBlock& block) const;
// Returns whether this loop information is an inner loop of `other`.
// Note that `other` *must* be populated before entering this function.
bool IsIn(const HLoopInformation& other) const;
// Returns true if instruction is not defined within this loop.
bool IsDefinedOutOfTheLoop(HInstruction* instruction) const;
const ArenaBitVector& GetBlocks() const { return blocks_; }
void Add(HBasicBlock* block);
void Remove(HBasicBlock* block);
void ClearAllBlocks() {
bool HasBackEdgeNotDominatedByHeader() const;
bool IsPopulated() const {
return blocks_.GetHighestBitSet() != -1;
bool DominatesAllBackEdges(HBasicBlock* block);
bool HasExitEdge() const;
// Resets back edge and blocks-in-loop data.
void ResetBasicBlockData() {
// Internal recursive implementation of `Populate`.
void PopulateRecursive(HBasicBlock* block);
void PopulateIrreducibleRecursive(HBasicBlock* block, ArenaBitVector* finalized);
HBasicBlock* header_;
HSuspendCheck* suspend_check_;
bool irreducible_;
bool contains_irreducible_loop_;
ArenaVector<HBasicBlock*> back_edges_;
ArenaBitVector blocks_;
// Stores try/catch information for basic blocks.
// Note that HGraph is constructed so that catch blocks cannot simultaneously
// be try blocks.
class TryCatchInformation : public ArenaObject<kArenaAllocTryCatchInfo> {
// Try block information constructor.
explicit TryCatchInformation(const HTryBoundary& try_entry)
: try_entry_(&try_entry),
catch_type_index_(DexFile::kDexNoIndex16) {
DCHECK(try_entry_ != nullptr);
// Catch block information constructor.
TryCatchInformation(dex::TypeIndex catch_type_index, const DexFile& dex_file)
: try_entry_(nullptr),
catch_type_index_(catch_type_index) {}
bool IsTryBlock() const { return try_entry_ != nullptr; }
const HTryBoundary& GetTryEntry() const {
return *try_entry_;
bool IsCatchBlock() const { return catch_dex_file_ != nullptr; }
bool IsCatchAllTypeIndex() const {
return !catch_type_index_.IsValid();
dex::TypeIndex GetCatchTypeIndex() const {
return catch_type_index_;
const DexFile& GetCatchDexFile() const {
return *catch_dex_file_;
// One of possibly several TryBoundary instructions entering the block's try.
// Only set for try blocks.
const HTryBoundary* try_entry_;
// Exception type information. Only set for catch blocks.
const DexFile* catch_dex_file_;
const dex::TypeIndex catch_type_index_;
static constexpr size_t kNoLifetime = -1;
static constexpr uint32_t kInvalidBlockId = static_cast<uint32_t>(-1);
// A block in a method. Contains the list of instructions represented
// as a double linked list. Each block knows its predecessors and
// successors.
class HBasicBlock : public ArenaObject<kArenaAllocBasicBlock> {
explicit HBasicBlock(HGraph* graph, uint32_t dex_pc = kNoDexPc)
: graph_(graph),
try_catch_information_(nullptr) {
const ArenaVector<HBasicBlock*>& GetPredecessors() const {
return predecessors_;
const ArenaVector<HBasicBlock*>& GetSuccessors() const {
return successors_;
ArrayRef<HBasicBlock* const> GetNormalSuccessors() const;
ArrayRef<HBasicBlock* const> GetExceptionalSuccessors() const;
bool HasSuccessor(const HBasicBlock* block, size_t start_from = 0u) {
return ContainsElement(successors_, block, start_from);
const ArenaVector<HBasicBlock*>& GetDominatedBlocks() const {
return dominated_blocks_;
bool IsEntryBlock() const {
return graph_->GetEntryBlock() == this;
bool IsExitBlock() const {
return graph_->GetExitBlock() == this;
bool IsSingleGoto() const;
bool IsSingleReturn() const;
bool IsSingleReturnOrReturnVoidAllowingPhis() const;
bool IsSingleTryBoundary() const;
// Returns true if this block emits nothing but a jump.
bool IsSingleJump() const {
HLoopInformation* loop_info = GetLoopInformation();
return (IsSingleGoto() || IsSingleTryBoundary())
// Back edges generate a suspend check.
&& (loop_info == nullptr || !loop_info->IsBackEdge(*this));
void AddBackEdge(HBasicBlock* back_edge) {
if (loop_information_ == nullptr) {
loop_information_ = new (graph_->GetAllocator()) HLoopInformation(this, graph_);
DCHECK_EQ(loop_information_->GetHeader(), this);
// Registers a back edge; if the block was not a loop header before the call associates a newly
// created loop info with it.
// Used in SuperblockCloner to preserve LoopInformation object instead of reseting loop
// info for all blocks during back edges recalculation.
void AddBackEdgeWhileUpdating(HBasicBlock* back_edge) {
if (loop_information_ == nullptr || loop_information_->GetHeader() != this) {
loop_information_ = new (graph_->GetAllocator()) HLoopInformation(this, graph_);
HGraph* GetGraph() const { return graph_; }
void SetGraph(HGraph* graph) { graph_ = graph; }
uint32_t GetBlockId() const { return block_id_; }
void SetBlockId(int id) { block_id_ = id; }
uint32_t GetDexPc() const { return dex_pc_; }
HBasicBlock* GetDominator() const { return dominator_; }
void SetDominator(HBasicBlock* dominator) { dominator_ = dominator; }
void AddDominatedBlock(HBasicBlock* block) { dominated_blocks_.push_back(block); }
void RemoveDominatedBlock(HBasicBlock* block) {
RemoveElement(dominated_blocks_, block);
void ReplaceDominatedBlock(HBasicBlock* existing, HBasicBlock* new_block) {
ReplaceElement(dominated_blocks_, existing, new_block);
void ClearDominanceInformation();
int NumberOfBackEdges() const {
return IsLoopHeader() ? loop_information_->NumberOfBackEdges() : 0;
HInstruction* GetFirstInstruction() const { return instructions_.first_instruction_; }
HInstruction* GetLastInstruction() const { return instructions_.last_instruction_; }
const HInstructionList& GetInstructions() const { return instructions_; }
HInstruction* GetFirstPhi() const { return phis_.first_instruction_; }
HInstruction* GetLastPhi() const { return phis_.last_instruction_; }
const HInstructionList& GetPhis() const { return phis_; }
HInstruction* GetFirstInstructionDisregardMoves() const;
void AddSuccessor(HBasicBlock* block) {
void ReplaceSuccessor(HBasicBlock* existing, HBasicBlock* new_block) {
size_t successor_index = GetSuccessorIndexOf(existing);
successors_[successor_index] = new_block;
void ReplacePredecessor(HBasicBlock* existing, HBasicBlock* new_block) {
size_t predecessor_index = GetPredecessorIndexOf(existing);
predecessors_[predecessor_index] = new_block;
// Insert `this` between `predecessor` and `successor. This method
// preserves the indicies, and will update the first edge found between
// `predecessor` and `successor`.
void InsertBetween(HBasicBlock* predecessor, HBasicBlock* successor) {
size_t predecessor_index = successor->GetPredecessorIndexOf(predecessor);
size_t successor_index = predecessor->GetSuccessorIndexOf(successor);
successor->predecessors_[predecessor_index] = this;
predecessor->successors_[successor_index] = this;
void RemovePredecessor(HBasicBlock* block) {
predecessors_.erase(predecessors_.begin() + GetPredecessorIndexOf(block));
void RemoveSuccessor(HBasicBlock* block) {
successors_.erase(successors_.begin() + GetSuccessorIndexOf(block));
void ClearAllPredecessors() {
void AddPredecessor(HBasicBlock* block) {
void SwapPredecessors() {
DCHECK_EQ(predecessors_.size(), 2u);
std::swap(predecessors_[0], predecessors_[1]);
void SwapSuccessors() {
DCHECK_EQ(successors_.size(), 2u);
std::swap(successors_[0], successors_[1]);
size_t GetPredecessorIndexOf(HBasicBlock* predecessor) const {
return IndexOfElement(predecessors_, predecessor);
size_t GetSuccessorIndexOf(HBasicBlock* successor) const {
return IndexOfElement(successors_, successor);
HBasicBlock* GetSinglePredecessor() const {
DCHECK_EQ(GetPredecessors().size(), 1u);
return GetPredecessors()[0];
HBasicBlock* GetSingleSuccessor() const {
DCHECK_EQ(GetSuccessors().size(), 1u);
return GetSuccessors()[0];
// Returns whether the first occurrence of `predecessor` in the list of
// predecessors is at index `idx`.
bool IsFirstIndexOfPredecessor(HBasicBlock* predecessor, size_t idx) const {
DCHECK_EQ(GetPredecessors()[idx], predecessor);
return GetPredecessorIndexOf(predecessor) == idx;
// Create a new block between this block and its predecessors. The new block
// is added to the graph, all predecessor edges are relinked to it and an edge
// is created to `this`. Returns the new empty block. Reverse post order or
// loop and try/catch information are not updated.
HBasicBlock* CreateImmediateDominator();
// Split the block into two blocks just before `cursor`. Returns the newly
// created, latter block. Note that this method will add the block to the
// graph, create a Goto at the end of the former block and will create an edge
// between the blocks. It will not, however, update the reverse post order or
// loop and try/catch information.
HBasicBlock* SplitBefore(HInstruction* cursor);
// Split the block into two blocks just before `cursor`. Returns the newly
// created block. Note that this method just updates raw block information,
// like predecessors, successors, dominators, and instruction list. It does not
// update the graph, reverse post order, loop information, nor make sure the
// blocks are consistent (for example ending with a control flow instruction).
HBasicBlock* SplitBeforeForInlining(HInstruction* cursor);
// Similar to `SplitBeforeForInlining` but does it after `cursor`.
HBasicBlock* SplitAfterForInlining(HInstruction* cursor);
// Merge `other` at the end of `this`. Successors and dominated blocks of
// `other` are changed to be successors and dominated blocks of `this`. Note
// that this method does not update the graph, reverse post order, loop
// information, nor make sure the blocks are consistent (for example ending
// with a control flow instruction).
void MergeWithInlined(HBasicBlock* other);
// Replace `this` with `other`. Predecessors, successors, and dominated blocks
// of `this` are moved to `other`.
// Note that this method does not update the graph, reverse post order, loop
// information, nor make sure the blocks are consistent (for example ending
// with a control flow instruction).
void ReplaceWith(HBasicBlock* other);
// Merges the instructions of `other` at the end of `this`.
void MergeInstructionsWith(HBasicBlock* other);
// Merge `other` at the end of `this`. This method updates loops, reverse post
// order, links to predecessors, successors, dominators and deletes the block
// from the graph. The two blocks must be successive, i.e. `this` the only
// predecessor of `other` and vice versa.
void MergeWith(HBasicBlock* other);
// Disconnects `this` from all its predecessors, successors and dominator,
// removes it from all loops it is included in and eventually from the graph.
// The block must not dominate any other block. Predecessors and successors
// are safely updated.
void DisconnectAndDelete();
void AddInstruction(HInstruction* instruction);
// Insert `instruction` before/after an existing instruction `cursor`.
void InsertInstructionBefore(HInstruction* instruction, HInstruction* cursor);
void InsertInstructionAfter(HInstruction* instruction, HInstruction* cursor);
// Replace phi `initial` with `replacement` within this block.
void ReplaceAndRemovePhiWith(HPhi* initial, HPhi* replacement);
// Replace instruction `initial` with `replacement` within this block.
void ReplaceAndRemoveInstructionWith(HInstruction* initial,
HInstruction* replacement);
void AddPhi(HPhi* phi);
void InsertPhiAfter(HPhi* instruction, HPhi* cursor);
// RemoveInstruction and RemovePhi delete a given instruction from the respective
// instruction list. With 'ensure_safety' set to true, it verifies that the
// instruction is not in use and removes it from the use lists of its inputs.
void RemoveInstruction(HInstruction* instruction, bool ensure_safety = true);
void RemovePhi(HPhi* phi, bool ensure_safety = true);
void RemoveInstructionOrPhi(HInstruction* instruction, bool ensure_safety = true);
bool IsLoopHeader() const {
return IsInLoop() && (loop_information_->GetHeader() == this);
bool IsLoopPreHeaderFirstPredecessor() const {
return GetPredecessors()[0] == GetLoopInformation()->GetPreHeader();
bool IsFirstPredecessorBackEdge() const {
return GetLoopInformation()->IsBackEdge(*GetPredecessors()[0]);
HLoopInformation* GetLoopInformation() const {
return loop_information_;
// Set the loop_information_ on this block. Overrides the current
// loop_information if it is an outer loop of the passed loop information.
// Note that this method is called while creating the loop information.
void SetInLoop(HLoopInformation* info) {
if (IsLoopHeader()) {
// Nothing to do. This just means `info` is an outer loop.
} else if (!IsInLoop()) {
loop_information_ = info;
} else if (loop_information_->Contains(*info->GetHeader())) {
// Block is currently part of an outer loop. Make it part of this inner loop.
// Note that a non loop header having a loop information means this loop information
// has already been populated
loop_information_ = info;
} else {
// Block is part of an inner loop. Do not update the loop information.
// Note that we cannot do the check `info->Contains(loop_information_)->GetHeader()`
// at this point, because this method is being called while populating `info`.
// Raw update of the loop information.
void SetLoopInformation(HLoopInformation* info) {
loop_information_ = info;
bool IsInLoop() const { return loop_information_ != nullptr; }
TryCatchInformation* GetTryCatchInformation() const { return try_catch_information_; }
void SetTryCatchInformation(TryCatchInformation* try_catch_information) {
try_catch_information_ = try_catch_information;
bool IsTryBlock() const {
return try_catch_information_ != nullptr && try_catch_information_->IsTryBlock();
bool IsCatchBlock() const {
return try_catch_information_ != nullptr && try_catch_information_->IsCatchBlock();
// Returns the try entry that this block's successors should have. They will
// be in the same try, unless the block ends in a try boundary. In that case,
// the appropriate try entry will be returned.
const HTryBoundary* ComputeTryEntryOfSuccessors() const;
bool HasThrowingInstructions() const;
// Returns whether this block dominates the blocked passed as parameter.
bool Dominates(HBasicBlock* block) const;
size_t GetLifetimeStart() const { return lifetime_start_; }
size_t GetLifetimeEnd() const { return lifetime_end_; }
void SetLifetimeStart(size_t start) { lifetime_start_ = start; }
void SetLifetimeEnd(size_t end) { lifetime_end_ = end; }
bool EndsWithControlFlowInstruction() const;
bool EndsWithReturn() const;
bool EndsWithIf() const;
bool EndsWithTryBoundary() const;
bool HasSinglePhi() const;
HGraph* graph_;
ArenaVector<HBasicBlock*> predecessors_;
ArenaVector<HBasicBlock*> successors_;
HInstructionList instructions_;
HInstructionList phis_;
HLoopInformation* loop_information_;
HBasicBlock* dominator_;
ArenaVector<HBasicBlock*> dominated_blocks_;
uint32_t block_id_;
// The dex program counter of the first instruction of this block.
const uint32_t dex_pc_;
size_t lifetime_start_;
size_t lifetime_end_;
TryCatchInformation* try_catch_information_;
friend class HGraph;
friend class HInstruction;
// Iterates over the LoopInformation of all loops which contain 'block'
// from the innermost to the outermost.
class HLoopInformationOutwardIterator : public ValueObject {
explicit HLoopInformationOutwardIterator(const HBasicBlock& block)
: current_(block.GetLoopInformation()) {}
bool Done() const { return current_ == nullptr; }
void Advance() {
current_ = current_->GetPreHeader()->GetLoopInformation();
HLoopInformation* Current() const {
return current_;
HLoopInformation* current_;
M(Above, Condition) \
M(AboveOrEqual, Condition) \
M(Abs, UnaryOperation) \
M(Add, BinaryOperation) \
M(And, BinaryOperation) \
M(ArrayGet, Instruction) \
M(ArrayLength, Instruction) \
M(ArraySet, Instruction) \
M(Below, Condition) \
M(BelowOrEqual, Condition) \
M(BooleanNot, UnaryOperation) \
M(BoundsCheck, Instruction) \
M(BoundType, Instruction) \
M(CheckCast, Instruction) \
M(ClassTableGet, Instruction) \
M(ClearException, Instruction) \
M(ClinitCheck, Instruction) \
M(Compare, BinaryOperation) \
M(ConstructorFence, Instruction) \
M(CurrentMethod, Instruction) \
M(ShouldDeoptimizeFlag, Instruction) \
M(Deoptimize, Instruction) \
M(Div, BinaryOperation) \
M(DivZeroCheck, Instruction) \
M(DoubleConstant, Constant) \
M(Equal, Condition) \
M(Exit, Instruction) \
M(FloatConstant, Constant) \
M(Goto, Instruction) \
M(GreaterThan, Condition) \
M(GreaterThanOrEqual, Condition) \
M(If, Instruction) \
M(InstanceFieldGet, Instruction) \
M(InstanceFieldSet, Instruction) \
M(InstanceOf, Instruction) \
M(IntConstant, Constant) \
M(IntermediateAddress, Instruction) \
M(InvokeUnresolved, Invoke) \
M(InvokeInterface, Invoke) \
M(InvokeStaticOrDirect, Invoke) \
M(InvokeVirtual, Invoke) \
M(InvokePolymorphic, Invoke) \
M(InvokeCustom, Invoke) \
M(LessThan, Condition) \
M(LessThanOrEqual, Condition) \
M(LoadClass, Instruction) \
M(LoadException, Instruction) \
M(LoadMethodHandle, Instruction) \
M(LoadMethodType, Instruction) \
M(LoadString, Instruction) \
M(LongConstant, Constant) \
M(Max, Instruction) \
M(MemoryBarrier, Instruction) \
M(Min, BinaryOperation) \
M(MonitorOperation, Instruction) \
M(Mul, BinaryOperation) \
M(NativeDebugInfo, Instruction) \
M(Neg, UnaryOperation) \
M(NewArray, Instruction) \
M(NewInstance, Instruction) \
M(Not, UnaryOperation) \
M(NotEqual, Condition) \
M(NullConstant, Instruction) \
M(NullCheck, Instruction) \
M(Or, BinaryOperation) \
M(PackedSwitch, Instruction) \
M(ParallelMove, Instruction) \
M(ParameterValue, Instruction) \
M(Phi, Instruction) \
M(Rem, BinaryOperation) \
M(Return, Instruction) \
M(ReturnVoid, Instruction) \
M(Ror, BinaryOperation) \
M(Shl, BinaryOperation) \
M(Shr, BinaryOperation) \
M(StaticFieldGet, Instruction) \
M(StaticFieldSet, Instruction) \
M(UnresolvedInstanceFieldGet, Instruction) \
M(UnresolvedInstanceFieldSet, Instruction) \
M(UnresolvedStaticFieldGet, Instruction) \
M(UnresolvedStaticFieldSet, Instruction) \
M(Select, Instruction) \
M(Sub, BinaryOperation) \
M(SuspendCheck, Instruction) \
M(Throw, Instruction) \
M(TryBoundary, Instruction) \
M(TypeConversion, Instruction) \
M(UShr, BinaryOperation) \
M(Xor, BinaryOperation) \
M(VecReplicateScalar, VecUnaryOperation) \
M(VecExtractScalar, VecUnaryOperation) \
M(VecReduce, VecUnaryOperation) \
M(VecCnv, VecUnaryOperation) \
M(VecNeg, VecUnaryOperation) \
M(VecAbs, VecUnaryOperation) \
M(VecNot, VecUnaryOperation) \
M(VecAdd, VecBinaryOperation) \
M(VecHalvingAdd, VecBinaryOperation) \
M(VecSub, VecBinaryOperation) \
M(VecMul, VecBinaryOperation) \
M(VecDiv, VecBinaryOperation) \
M(VecMin, VecBinaryOperation) \
M(VecMax, VecBinaryOperation) \
M(VecAnd, VecBinaryOperation) \
M(VecAndNot, VecBinaryOperation) \
M(VecOr, VecBinaryOperation) \
M(VecXor, VecBinaryOperation) \
M(VecSaturationAdd, VecBinaryOperation) \
M(VecSaturationSub, VecBinaryOperation) \
M(VecShl, VecBinaryOperation) \
M(VecShr, VecBinaryOperation) \
M(VecUShr, VecBinaryOperation) \
M(VecSetScalars, VecOperation) \
M(VecMultiplyAccumulate, VecOperation) \
M(VecSADAccumulate, VecOperation) \
M(VecDotProd, VecOperation) \
M(VecLoad, VecMemoryOperation) \
M(VecStore, VecMemoryOperation) \
* Instructions, shared across several (not all) architectures.
#if !defined(ART_ENABLE_CODEGEN_arm) && !defined(ART_ENABLE_CODEGEN_arm64)
M(BitwiseNegatedRight, Instruction) \
M(DataProcWithShifterOp, Instruction) \
M(MultiplyAccumulate, Instruction) \
M(IntermediateAddressIndex, Instruction)
M(MipsComputeBaseMethodAddress, Instruction) \
M(MipsPackedSwitch, Instruction) \
M(IntermediateArrayAddressIndex, Instruction)
M(X86ComputeBaseMethodAddress, Instruction) \
M(X86LoadFromConstantTable, Instruction) \
M(X86FPNeg, Instruction) \
M(X86PackedSwitch, Instruction)
#if defined(ART_ENABLE_CODEGEN_x86) || defined(ART_ENABLE_CODEGEN_x86_64)
M(X86AndNot, Instruction) \
M(X86MaskOrResetLeastSetBit, Instruction)
M(Condition, BinaryOperation) \
M(Constant, Instruction) \
M(UnaryOperation, Instruction) \
M(BinaryOperation, Instruction) \
M(Invoke, Instruction) \
M(VecOperation, Instruction) \
M(VecUnaryOperation, VecOperation) \
M(VecBinaryOperation, VecOperation) \
M(VecMemoryOperation, VecOperation)
#define FORWARD_DECLARATION(type, super) class H##type;
private: \
H##type& operator=(const H##type&) = delete; \
public: \
const char* DebugName() const override { return #type; } \
HInstruction* Clone(ArenaAllocator* arena) const override { \
DCHECK(IsClonable()); \
return new (arena) H##type(*this->As##type()); \
} \
void Accept(HGraphVisitor* visitor) override
private: \
H##type& operator=(const H##type&) = delete; \
explicit H##type(const H##type& other) = default;
template <typename T>
class HUseListNode : public ArenaObject<kArenaAllocUseListNode>,
public IntrusiveForwardListNode<HUseListNode<T>> {
// Get the instruction which has this use as one of the inputs.
T GetUser() const { return user_; }
// Get the position of the input record that this use corresponds to.
size_t GetIndex() const { return index_; }
// Set the position of the input record that this use corresponds to.
void SetIndex(size_t index) { index_ = index; }
HUseListNode(T user, size_t index)
: user_(user), index_(index) {}
T const user_;
size_t index_;
friend class HInstruction;
template <typename T>
using HUseList = IntrusiveForwardList<HUseListNode<T>>;
// This class is used by HEnvironment and HInstruction classes to record the
// instructions they use and pointers to the corresponding HUseListNodes kept
// by the used instructions.
template <typename T>
class HUserRecord : public ValueObject {
HUserRecord() : instruction_(nullptr), before_use_node_() {}
explicit HUserRecord(HInstruction* instruction) : instruction_(instruction), before_use_node_() {}
HUserRecord(const HUserRecord<T>& old_record, typename HUseList<T>::iterator before_use_node)
: HUserRecord(old_record.instruction_, before_use_node) {}
HUserRecord(HInstruction* instruction, typename HUseList<T>::iterator before_use_node)
: instruction_(instruction), before_use_node_(before_use_node) {
DCHECK(instruction_ != nullptr);
HInstruction* GetInstruction() const { return instruction_; }
typename HUseList<T>::iterator GetBeforeUseNode() const { return before_use_node_; }
typename HUseList<T>::iterator GetUseNode() const { return ++GetBeforeUseNode(); }
// Instruction used by the user.
HInstruction* instruction_;
// Iterator before the corresponding entry in the use list kept by 'instruction_'.
typename HUseList<T>::iterator before_use_node_;
// Helper class that extracts the input instruction from HUserRecord<HInstruction*>.
// This is used for HInstruction::GetInputs() to return a container wrapper providing
// HInstruction* values even though the underlying container has HUserRecord<>s.
struct HInputExtractor {
HInstruction* operator()(HUserRecord<HInstruction*>& record) const {
return record.GetInstruction();
const HInstruction* operator()(const HUserRecord<HInstruction*>& record) const {
return record.GetInstruction();
using HInputsRef = TransformArrayRef<HUserRecord<HInstruction*>, HInputExtractor>;
using HConstInputsRef = TransformArrayRef<const HUserRecord<HInstruction*>, HInputExtractor>;
* Side-effects representation.
* For write/read dependences on fields/arrays, the dependence analysis uses
* type disambiguation (e.g. a float field write cannot modify the value of an
* integer field read) and the access type (e.g. a reference array write cannot
* modify the value of a reference field read [although it may modify the
* reference fetch prior to reading the field, which is represented by its own
* write/read dependence]). The analysis makes conservative points-to
* assumptions on reference types (e.g. two same typed arrays are assumed to be
* the same, and any reference read depends on any reference read without
* further regard of its type).
* kDependsOnGCBit is defined in the following way: instructions with kDependsOnGCBit must not be
* alive across the point where garbage collection might happen.
* Note: Instructions with kCanTriggerGCBit do not depend on each other.
* kCanTriggerGCBit must be used for instructions for which GC might happen on the path across
* those instructions from the compiler perspective (between this instruction and the next one
* in the IR).
* Note: Instructions which can cause GC only on a fatal slow path do not need
* kCanTriggerGCBit as the execution never returns to the instruction next to the exceptional
* one. However the execution may return to compiled code if there is a catch block in the
* current method; for this purpose the TryBoundary exit instruction has kCanTriggerGCBit
* set.
* The internal representation uses 38-bit and is described in the table below.
* The first line indicates the side effect, and for field/array accesses the
* second line indicates the type of the access (in the order of the
* DataType::Type enum).
* The two numbered lines below indicate the bit position in the bitfield (read
* vertically).
* |Depends on GC|ARRAY-R |FIELD-R |Can trigger GC|ARRAY-W |FIELD-W |
* +-------------+---------+---------+--------------+---------+---------+
* | 3 |333333322|222222221| 1 |111111110|000000000|
* | 7 |654321098|765432109| 8 |765432109|876543210|
* Note that, to ease the implementation, 'changes' bits are least significant
* bits, while 'dependency' bits are most significant bits.
class SideEffects : public ValueObject {
SideEffects() : flags_(0) {}
static SideEffects None() {
return SideEffects(0);
static SideEffects All() {
return SideEffects(kAllChangeBits | kAllDependOnBits);
static SideEffects AllChanges() {
return SideEffects(kAllChangeBits);
static SideEffects AllDependencies() {
return SideEffects(kAllDependOnBits);
static SideEffects AllExceptGCDependency() {
return AllWritesAndReads().Union(SideEffects::CanTriggerGC());
static SideEffects AllWritesAndReads() {
return SideEffects(kAllWrites | kAllReads);
static SideEffects AllWrites() {
return SideEffects(kAllWrites);
static SideEffects AllReads() {
return SideEffects(kAllReads);
static SideEffects FieldWriteOfType(DataType::Type type, bool is_volatile) {
return is_volatile
? AllWritesAndReads()
: SideEffects(TypeFlag(type, kFieldWriteOffset));
static SideEffects ArrayWriteOfType(DataType::Type type) {
return SideEffects(TypeFlag(type, kArrayWriteOffset));
static SideEffects FieldReadOfType(DataType::Type type, bool is_volatile) {
return is_volatile
? AllWritesAndReads()
: SideEffects(TypeFlag(type, kFieldReadOffset));
static SideEffects ArrayReadOfType(DataType::Type type) {
return SideEffects(TypeFlag(type, kArrayReadOffset));
// Returns whether GC might happen across this instruction from the compiler perspective so
// the next instruction in the IR would see that.
// See the SideEffect class comments.
static SideEffects CanTriggerGC() {
return SideEffects(1ULL << kCanTriggerGCBit);
// Returns whether the instruction must not be alive across a GC point.
// See the SideEffect class comments.
static SideEffects DependsOnGC() {
return SideEffects(1ULL << kDependsOnGCBit);
// Combines the side-effects of this and the other.
SideEffects Union(SideEffects other) const {
return SideEffects(flags_ | other.flags_);
SideEffects Exclusion(SideEffects other) const {
return SideEffects(flags_ & ~other.flags_);
void Add(SideEffects other) {
flags_ |= other.flags_;
bool Includes(SideEffects other) const {
return (other.flags_ & flags_) == other.flags_;
bool HasSideEffects() const {
return (flags_ & kAllChangeBits);
bool HasDependencies() const {
return (flags_ & kAllDependOnBits);
// Returns true if there are no side effects or dependencies.
bool DoesNothing() const {
return flags_ == 0;
// Returns true if something is written.
bool DoesAnyWrite() const {
return (flags_ & kAllWrites);
// Returns true if something is read.
bool DoesAnyRead() const {
return (flags_ & kAllReads);
// Returns true if potentially everything is written and read
// (every type and every kind of access).
bool DoesAllReadWrite() const {
return (flags_ & (kAllWrites | kAllReads)) == (kAllWrites | kAllReads);
bool DoesAll() const {
return flags_ == (kAllChangeBits | kAllDependOnBits);
// Returns true if `this` may read something written by `other`.
bool MayDependOn(SideEffects other) const {
const uint64_t depends_on_flags = (flags_ & kAllDependOnBits) >> kChangeBits;
return (other.flags_ & depends_on_flags);
// Returns string representation of flags (for debugging only).
std::string ToString() const {
std::string flags = "|";
for (int s = kLastBit; s >= 0; s--) {
bool current_bit_is_set = ((flags_ >> s) & 1) != 0;
if ((s == kDependsOnGCBit) || (s == kCanTriggerGCBit)) {
// This is a bit for the GC side effect.
if (current_bit_is_set) {
flags += "GC";
flags += "|";
} else {
// This is a bit for the array/field analysis.
// The underscore character stands for the 'can trigger GC' bit.
if (current_bit_is_set) {
flags += kDebug[s];
if ((s == kFieldWriteOffset) || (s == kArrayWriteOffset) ||
(s == kFieldReadOffset) || (s == kArrayReadOffset)) {
flags += "|";
return flags;
bool Equals(const SideEffects& other) const { return flags_ == other.flags_; }
static constexpr int kFieldArrayAnalysisBits = 9;
static constexpr int kFieldWriteOffset = 0;
static constexpr int kArrayWriteOffset = kFieldWriteOffset + kFieldArrayAnalysisBits;
static constexpr int kLastBitForWrites = kArrayWriteOffset + kFieldArrayAnalysisBits - 1;
static constexpr int kCanTriggerGCBit = kLastBitForWrites + 1;
static constexpr int kChangeBits = kCanTriggerGCBit + 1;
static constexpr int kFieldReadOffset = kCanTriggerGCBit + 1;
static constexpr int kArrayReadOffset = kFieldReadOffset + kFieldArrayAnalysisBits;
static constexpr int kLastBitForReads = kArrayReadOffset + kFieldArrayAnalysisBits - 1;
static constexpr int kDependsOnGCBit = kLastBitForReads + 1;
static constexpr int kLastBit = kDependsOnGCBit;
static constexpr int kDependOnBits = kLastBit + 1 - kChangeBits;
// Aliases.
static_assert(kChangeBits == kDependOnBits,
"the 'change' bits should match the 'depend on' bits.");
static constexpr uint64_t kAllChangeBits = ((1ULL << kChangeBits) - 1);
static constexpr uint64_t kAllDependOnBits = ((1ULL << kDependOnBits) - 1) << kChangeBits;
static constexpr uint64_t kAllWrites =
((1ULL << (kLastBitForWrites + 1 - kFieldWriteOffset)) - 1) << kFieldWriteOffset;
static constexpr uint64_t kAllReads =
((1ULL << (kLastBitForReads + 1 - kFieldReadOffset)) - 1) << kFieldReadOffset;
// Translates type to bit flag. The type must correspond to a Java type.
static uint64_t TypeFlag(DataType::Type type, int offset) {
int shift;
switch (type) {
case DataType::Type::kReference: shift = 0; break;
case DataType::Type::kBool: shift = 1; break;
case DataType::Type::kInt8: shift = 2; break;
case DataType::Type::kUint16: shift = 3; break;
case DataType::Type::kInt16: shift = 4; break;
case DataType::Type::kInt32: shift = 5; break;
case DataType::Type::kInt64: shift = 6; break;
case DataType::Type::kFloat32: shift = 7; break;
case DataType::Type::kFloat64: shift = 8; break;
LOG(FATAL) << "Unexpected data type " << type;
DCHECK_LE(kFieldWriteOffset, shift);
DCHECK_LT(shift, kArrayWriteOffset);
return UINT64_C(1) << (shift + offset);
// Private constructor on direct flags value.
explicit SideEffects(uint64_t flags) : flags_(flags) {}
uint64_t flags_;
// A HEnvironment object contains the values of virtual registers at a given location.
class HEnvironment : public ArenaObject<kArenaAllocEnvironment> {
ALWAYS_INLINE HEnvironment(ArenaAllocator* allocator,
size_t number_of_vregs,
ArtMethod* method,
uint32_t dex_pc,
HInstruction* holder)
: vregs_(number_of_vregs, allocator->Adapter(kArenaAllocEnvironmentVRegs)),
holder_(holder) {
ALWAYS_INLINE HEnvironment(ArenaAllocator* allocator,
const HEnvironment& to_copy,
HInstruction* holder)
: HEnvironment(allocator,
holder) {}
void AllocateLocations() {
void SetAndCopyParentChain(ArenaAllocator* allocator, HEnvironment* parent) {
if (parent_ != nullptr) {
parent_->SetAndCopyParentChain(allocator, parent);
} else {
parent_ = new (allocator) HEnvironment(allocator, *parent, holder_);
if (parent->GetParent() != nullptr) {
parent_->SetAndCopyParentChain(allocator, parent->GetParent());
void CopyFrom(ArrayRef<HInstruction* const> locals);
void CopyFrom(HEnvironment* environment);
// Copy from `env`. If it's a loop phi for `loop_header`, copy the first
// input to the loop phi instead. This is for inserting instructions that
// require an environment (like HDeoptimization) in the loop pre-header.
void CopyFromWithLoopPhiAdjustment(HEnvironment* env, HBasicBlock* loop_header);
void SetRawEnvAt(size_t index, HInstruction* instruction) {
vregs_[index] = HUserRecord<HEnvironment*>(instruction);
HInstruction* GetInstructionAt(size_t index) const {
return vregs_[index].GetInstruction();
void RemoveAsUserOfInput(size_t index) const;
// Replaces the input at the position 'index' with the replacement; the replacement and old
// input instructions' env_uses_ lists are adjusted. The function works similar to
// HInstruction::ReplaceInput.
void ReplaceInput(HInstruction* replacement, size_t index);
size_t Size() const { return vregs_.size(); }
HEnvironment* GetParent() const { return parent_; }
void SetLocationAt(size_t index, Location location) {
locations_[index] = location;
Location GetLocationAt(size_t index) const {
return locations_[index];
uint32_t GetDexPc() const {
return dex_pc_;
ArtMethod* GetMethod() const {
return method_;
HInstruction* GetHolder() const {
return holder_;
bool IsFromInlinedInvoke() const {
return GetParent() != nullptr;
ArenaVector<HUserRecord<HEnvironment*>> vregs_;
ArenaVector<Location> locations_;
HEnvironment* parent_;
ArtMethod* method_;
const uint32_t dex_pc_;
// The instruction that holds this environment.
HInstruction* const holder_;
friend class HInstruction;
class HInstruction : public ArenaObject<kArenaAllocInstruction> {
#define DECLARE_KIND(type, super) k##type,
enum InstructionKind {
HInstruction(InstructionKind kind, SideEffects side_effects, uint32_t dex_pc)
: HInstruction(kind, DataType::Type::kVoid, side_effects, dex_pc) {}
HInstruction(InstructionKind kind, DataType::Type type, SideEffects side_effects, uint32_t dex_pc)
: previous_(nullptr),
reference_type_handle_(ReferenceTypeInfo::CreateInvalid().GetTypeHandle()) {
virtual ~HInstruction() {}
HInstruction* GetNext() const { return next_; }
HInstruction* GetPrevious() const { return previous_; }
HInstruction* GetNextDisregardingMoves() const;
HInstruction* GetPreviousDisregardingMoves() const;
HBasicBlock* GetBlock() const { return block_; }
ArenaAllocator* GetAllocator() const { return block_->GetGraph()->GetAllocator(); }
void SetBlock(HBasicBlock* block) { block_ = block; }
bool IsInBlock() const { return block_ != nullptr; }
bool IsInLoop() const { return block_->IsInLoop(); }
bool IsLoopHeaderPhi() const { return IsPhi() && block_->IsLoopHeader(); }
bool IsIrreducibleLoopHeaderPhi() const {
return IsLoopHeaderPhi() && GetBlock()->GetLoopInformation()->IsIrreducible();
virtual ArrayRef<HUserRecord<HInstruction*>> GetInputRecords() = 0;
ArrayRef<const HUserRecord<HInstruction*>> GetInputRecords() const {
// One virtual method is enough, just const_cast<> and then re-add the const.
return ArrayRef<const HUserRecord<HInstruction*>>(
HInputsRef GetInputs() {
return MakeTransformArrayRef(GetInputRecords(), HInputExtractor());
HConstInputsRef GetInputs() const {
return MakeTransformArrayRef(GetInputRecords(), HInputExtractor());
size_t InputCount() const { return GetInputRecords().size(); }
HInstruction* InputAt(size_t i) const { return InputRecordAt(i).GetInstruction(); }
bool HasInput(HInstruction* input) const {
for (const HInstruction* i : GetInputs()) {
if (i == input) {
return true;
return false;
void SetRawInputAt(size_t index, HInstruction* input) {
SetRawInputRecordAt(index, HUserRecord<HInstruction*>(input));
virtual void Accept(HGraphVisitor* visitor) = 0;
virtual const char* DebugName() const = 0;
DataType::Type GetType() const {
return TypeField::Decode(GetPackedFields());
virtual bool NeedsEnvironment() const { return false; }
uint32_t GetDexPc() const { return dex_pc_; }
virtual bool IsControlFlow() const { return false; }
// Can the instruction throw?
// TODO: We should rename to CanVisiblyThrow, as some instructions (like HNewInstance),
// could throw OOME, but it is still OK to remove them if they are unused.
virtual bool CanThrow() const { return false; }
// Does the instruction always throw an exception unconditionally?
virtual bool AlwaysThrows() const { return false; }
bool CanThrowIntoCatchBlock() const { return CanThrow() && block_->IsTryBlock(); }
bool HasSideEffects() const { return side_effects_.HasSideEffects(); }
bool DoesAnyWrite() const { return side_effects_.DoesAnyWrite(); }
// Does not apply for all instructions, but having this at top level greatly
// simplifies the null check elimination.
// TODO: Consider merging can_be_null into ReferenceTypeInfo.
virtual bool CanBeNull() const {
DCHECK_EQ(GetType(), DataType::Type::kReference) << "CanBeNull only applies to reference types";
return true;
virtual bool CanDoImplicitNullCheckOn(HInstruction* obj ATTRIBUTE_UNUSED) const {
return false;
// If this instruction will do an implicit null check, return the `HNullCheck` associated
// with it. Otherwise return null.
HNullCheck* GetImplicitNullCheck() const {
// Find the first previous instruction which is not a move.
HInstruction* first_prev_not_move = GetPreviousDisregardingMoves();
if (first_prev_not_move != nullptr &&
first_prev_not_move->IsNullCheck() &&
first_prev_not_move->IsEmittedAtUseSite()) {
return first_prev_not_move->AsNullCheck();
return nullptr;
virtual bool IsActualObject() const {
return GetType() == DataType::Type::kReference;
void SetReferenceTypeInfo(ReferenceTypeInfo rti);
ReferenceTypeInfo GetReferenceTypeInfo() const {
DCHECK_EQ(GetType(), DataType::Type::kReference);
return ReferenceTypeInfo::CreateUnchecked(reference_type_handle_,
void AddUseAt(HInstruction* user, size_t index) {
DCHECK(user != nullptr);
// Note: fixup_end remains valid across push_front().
auto fixup_end = uses_.empty() ? uses_.begin() : ++uses_.begin();
HUseListNode<HInstruction*>* new_node =
new (GetBlock()->GetGraph()->GetAllocator()) HUseListNode<HInstruction*>(user, index);
void AddEnvUseAt(HEnvironment* user, size_t index) {
DCHECK(user != nullptr);
// Note: env_fixup_end remains valid across push_front().
auto env_fixup_end = env_uses_.empty() ? env_uses_.begin() : ++env_uses_.begin();
HUseListNode<HEnvironment*>* new_node =
new (GetBlock()->GetGraph()->GetAllocator()) HUseListNode<HEnvironment*>(user, index);
void RemoveAsUserOfInput(size_t input) {
HUserRecord<HInstruction*> input_use = InputRecordAt(input);
HUseList<HInstruction*>::iterator before_use_node = input_use.GetBeforeUseNode();
void RemoveAsUserOfAllInputs() {
for (const HUserRecord<HInstruction*>& input_use : GetInputRecords()) {
HUseList<HInstruction*>::iterator before_use_node = input_use.GetBeforeUseNode();
const HUseList<HInstruction*>& GetUses() const { return uses_; }
const HUseList<HEnvironment*>& GetEnvUses() const { return env_uses_; }
bool HasUses() const { return !uses_.empty() || !env_uses_.empty(); }
bool HasEnvironmentUses() const { return !env_uses_.empty(); }
bool HasNonEnvironmentUses() const { return !uses_.empty(); }
bool HasOnlyOneNonEnvironmentUse() const {
return !HasEnvironmentUses() && GetUses().HasExactlyOneElement();
bool IsRemovable() const {
!DoesAnyWrite() &&
!CanThrow() &&
!IsSuspendCheck() &&
!IsControlFlow() &&
!IsNativeDebugInfo() &&
!IsParameterValue() &&
// If we added an explicit barrier then we should keep it.
!IsMemoryBarrier() &&
bool IsDeadAndRemovable() const {
return IsRemovable() && !HasUses();
// Does this instruction strictly dominate `other_instruction`?
// Returns false if this instruction and `other_instruction` are the same.
// Aborts if this instruction and `other_instruction` are both phis.
bool StrictlyDominates(HInstruction* other_instruction) const;
int GetId() const { return id_; }
void SetId(int id) { id_ = id; }
int GetSsaIndex() const { return ssa_index_; }
void SetSsaIndex(int ssa_index) { ssa_index_ = ssa_index; }
bool HasSsaIndex() const { return ssa_index_ != -1; }
bool HasEnvironment() const { return environment_ != nullptr; }
HEnvironment* GetEnvironment() const { return environment_; }
// Set the `environment_` field. Raw because this method does not
// update the uses lists.
void SetRawEnvironment(HEnvironment* environment) {
DCHECK(environment_ == nullptr);
DCHECK_EQ(environment->GetHolder(), this);
environment_ = environment;
void InsertRawEnvironment(HEnvironment* environment) {
DCHECK(environment_ != nullptr);
DCHECK_EQ(environment->GetHolder(), this);
DCHECK(environment->GetParent() == nullptr);
environment->parent_ = environment_;
environment_ = environment;
void RemoveEnvironment();
// Set the environment of this instruction, copying it from `environment`. While
// copying, the uses lists are being updated.
void CopyEnvironmentFrom(HEnvironment* environment) {
DCHECK(environment_ == nullptr);
ArenaAllocator* allocator = GetBlock()->GetGraph()->GetAllocator();
environment_ = new (allocator) HEnvironment(allocator, *environment, this);
if (environment->GetParent() != nullptr) {
environment_->SetAndCopyParentChain(allocator, environment->GetParent());
void CopyEnvironmentFromWithLoopPhiAdjustment(HEnvironment* environment,
HBasicBlock* block) {
DCHECK(environment_ == nullptr);
ArenaAllocator* allocator = GetBlock()->GetGraph()->GetAllocator();
environment_ = new (allocator) HEnvironment(allocator, *environment, this);
environment_->CopyFromWithLoopPhiAdjustment(environment, block);
if (environment->GetParent() != nullptr) {
environment_->SetAndCopyParentChain(allocator, environment->GetParent());
// Returns the number of entries in the environment. Typically, that is the
// number of dex registers in a method. It could be more in case of inlining.
size_t EnvironmentSize() const;
LocationSummary* GetLocations() const { return locations_; }
void SetLocations(LocationSummary* locations) { locations_ = locations; }
void ReplaceWith(HInstruction* instruction);
void ReplaceUsesDominatedBy(HInstruction* dominator, HInstruction* replacement);
void ReplaceEnvUsesDominatedBy(HInstruction* dominator, HInstruction* replacement);
void ReplaceInput(HInstruction* replacement, size_t index);
// This is almost the same as doing `ReplaceWith()`. But in this helper, the
// uses of this instruction by `other` are *not* updated.
void ReplaceWithExceptInReplacementAtIndex(HInstruction* other, size_t use_index) {
other->ReplaceInput(this, use_index);
// Move `this` instruction before `cursor`
void MoveBefore(HInstruction* cursor, bool do_checks = true);
// Move `this` before its first user and out of any loops. If there is no
// out-of-loop user that dominates all other users, move the instruction
// to the end of the out-of-loop common dominator of the user's blocks.
// This can be used only on non-throwing instructions with no side effects that
// have at least one use but no environment uses.
void MoveBeforeFirstUserAndOutOfLoops();
#define INSTRUCTION_TYPE_CHECK(type, super) \
bool Is##type() const;
#define INSTRUCTION_TYPE_CAST(type, super) \
const H##type* As##type() const; \
H##type* As##type();
// Return a clone of the instruction if it is clonable (shallow copy by default, custom copy
// if a custom copy-constructor is provided for a particular type). If IsClonable() is false for
// the instruction then the behaviour of this function is undefined.
// Note: It is semantically valid to create a clone of the instruction only until
// prepare_for_register_allocator phase as lifetime, intervals and codegen info are not
// copied.
// Note: HEnvironment and some other fields are not copied and are set to default values, see
// 'explicit HInstruction(const HInstruction& other)' for details.
virtual HInstruction* Clone(ArenaAllocator* arena ATTRIBUTE_UNUSED) const {
LOG(FATAL) << "Cloning is not implemented for the instruction " <<
DebugName() << " " << GetId();
// Return whether instruction can be cloned (copied).
virtual bool IsClonable() const { return false; }
// Returns whether the instruction can be moved within the graph.
// TODO: this method is used by LICM and GVN with possibly different
// meanings? split and rename?
virtual bool CanBeMoved() const { return false; }
// Returns whether any data encoded in the two instructions is equal.
// This method does not look at the inputs. Both instructions must be
// of the same type, otherwise the method has undefined behavior.
virtual bool InstructionDataEquals(const HInstruction* other ATTRIBUTE_UNUSED) const {
return false;
// Returns whether two instructions are equal, that is:
// 1) They have the same type and contain the same data (InstructionDataEquals).
// 2) Their inputs are identical.
bool Equals(const HInstruction* other) const;
// TODO: Remove this indirection when the [[pure]] attribute proposal (n3744)
// is adopted and implemented by our C++ compiler(s). Fow now, we need to hide
// the virtual function because the __attribute__((__pure__)) doesn't really
// apply the strong requirement for virtual functions, preventing optimizations.
InstructionKind GetKind() const { return GetPackedField<InstructionKindField>(); }
virtual size_t ComputeHashCode() const {
size_t result = GetKind();
for (const HInstruction* input : GetInputs()) {
result = (result * 31) + input->GetId();
return result;
SideEffects GetSideEffects() const { return side_effects_; }
void SetSideEffects(SideEffects other) { side_effects_ = other; }
void AddSideEffects(SideEffects other) { side_effects_.Add(other); }
size_t GetLifetimePosition() const { return lifetime_position_; }
void SetLifetimePosition(size_t position) { lifetime_position_ = position; }
LiveInterval* GetLiveInterval() const { return live_interval_; }
void SetLiveInterval(LiveInterval* interval) { live_interval_ = interval; }
bool HasLiveInterval() const { return live_interval_ != nullptr; }
bool IsSuspendCheckEntry() const { return IsSuspendCheck() && GetBlock()->IsEntryBlock(); }
// Returns whether the code generation of the instruction will require to have access
// to the current method. Such instructions are:
// (1): Instructions that require an environment, as calling the runtime requires
// to walk the stack and have the current method stored at a specific stack address.
// (2): HCurrentMethod, potentially used by HInvokeStaticOrDirect, HLoadString, or HLoadClass
// to access the dex cache.
bool NeedsCurrentMethod() const {
return NeedsEnvironment() || IsCurrentMethod();
// Returns whether the code generation of the instruction will require to have access
// to the dex cache of the current method's declaring class via the current method.
virtual bool NeedsDexCacheOfDeclaringClass() const { return false; }
// Does this instruction have any use in an environment before
// control flow hits 'other'?
bool HasAnyEnvironmentUseBefore(HInstruction* other);
// Remove all references to environment uses of this instruction.
// The caller must ensure that this is safe to do.
void RemoveEnvironmentUsers();
bool IsEmittedAtUseSite() const { return GetPackedFlag<kFlagEmittedAtUseSite>(); }
void MarkEmittedAtUseSite() { SetPackedFlag<kFlagEmittedAtUseSite>(true); }
// If set, the machine code for this instruction is assumed to be generated by
// its users. Used by liveness analysis to compute use positions accordingly.
static constexpr size_t kFlagEmittedAtUseSite = 0u;
static constexpr size_t kFlagReferenceTypeIsExact = kFlagEmittedAtUseSite + 1;
static constexpr size_t kFieldInstructionKind = kFlagReferenceTypeIsExact + 1;
static constexpr size_t kFieldInstructionKindSize =
MinimumBitsToStore(static_cast<size_t>(InstructionKind::kLastInstructionKind - 1));
static constexpr size_t kFieldType =
kFieldInstructionKind + kFieldInstructionKindSize;
static constexpr size_t kFieldTypeSize =
static constexpr size_t kNumberOfGenericPackedBits = kFieldType + kFieldTypeSize;
static constexpr size_t kMaxNumberOfPackedBits = sizeof(uint32_t) * kBitsPerByte;
static_assert(kNumberOfGenericPackedBits <= kMaxNumberOfPackedBits,
"Too many generic packed fields");
using TypeField = BitField<DataType::Type, kFieldType, kFieldTypeSize>;
const HUserRecord<HInstruction*> InputRecordAt(size_t i) const {
return GetInputRecords()[i];
void SetRawInputRecordAt(size_t index, const HUserRecord<HInstruction*>& input) {
ArrayRef<HUserRecord<HInstruction*>> input_records = GetInputRecords();
input_records[index] = input;
uint32_t GetPackedFields() const {
return packed_fields_;
template <size_t flag>
bool GetPackedFlag() const {
return (packed_fields_ & (1u << flag)) != 0u;
template <size_t flag>
void SetPackedFlag(bool value = true) {
packed_fields_ = (packed_fields_ & ~(1u << flag)) | ((value ? 1u : 0u) << flag);
template <typename BitFieldType>
typename BitFieldType::value_type GetPackedField() const {
return BitFieldType::Decode(packed_fields_);
template <typename BitFieldType>
void SetPackedField(typename BitFieldType::value_type value) {
packed_fields_ = BitFieldType::Update(value, packed_fields_);
// Copy construction for the instruction (used for Clone function).
// Fields (e.g. lifetime, intervals and codegen info) associated with phases starting from
// prepare_for_register_allocator are not copied (set to default values).
// Copy constructors must be provided for every HInstruction type; default copy constructor is
// fine for most of them. However for some of the instructions a custom copy constructor must be
// specified (when instruction has non-trivially copyable fields and must have a special behaviour
// for copying them).
explicit HInstruction(const HInstruction& other)
: previous_(nullptr),
reference_type_handle_(other.reference_type_handle_) {
using InstructionKindField =
BitField<InstructionKind, kFieldInstructionKind, kFieldInstructionKindSize>;
void FixUpUserRecordsAfterUseInsertion(HUseList<HInstruction*>::iterator fixup_end) {
auto before_use_node = uses_.before_begin();
for (auto use_node = uses_.begin(); use_node != fixup_end; ++use_node) {
HInstruction* user = use_node->GetUser();
size_t input_index = use_node->GetIndex();
user->SetRawInputRecordAt(input_index, HUserRecord<HInstruction*>(this, before_use_node));
before_use_node = use_node;
void FixUpUserRecordsAfterUseRemoval(HUseList<HInstruction*>::iterator before_use_node) {
auto next = ++HUseList<HInstruction*>::iterator(before_use_node);
if (next != uses_.end()) {
HInstruction* next_user = next->GetUser();
size_t next_index = next->GetIndex();
DCHECK(next_user->InputRecordAt(next_index).GetInstruction() == this);
next_user->SetRawInputRecordAt(next_index, HUserRecord<HInstruction*>(this, before_use_node));
void FixUpUserRecordsAfterEnvUseInsertion(HUseList<HEnvironment*>::iterator env_fixup_end) {
auto before_env_use_node = env_uses_.before_begin();
for (auto env_use_node = env_uses_.begin(); env_use_node != env_fixup_end; ++env_use_node) {
HEnvironment* user = env_use_node->GetUser();
size_t input_index = env_use_node->GetIndex();
user->vregs_[input_index] = HUserRecord<HEnvironment*>(this, before_env_use_node);
before_env_use_node = env_use_node;
void FixUpUserRecordsAfterEnvUseRemoval(HUseList<HEnvironment*>::iterator before_env_use_node) {
auto next = ++HUseList<HEnvironment*>::iterator(before_env_use_node);
if (next != env_uses_.end()) {
HEnvironment* next_user = next->GetUser();
size_t next_index = next->GetIndex();
DCHECK(next_user->vregs_[next_index].GetInstruction() == this);
next_user->vregs_[next_index] = HUserRecord<HEnvironment*>(this, before_env_use_node);
HInstruction* previous_;
HInstruction* next_;
HBasicBlock* block_;
const uint32_t dex_pc_;
// An instruction gets an id when it is added to the graph.
// It reflects creation order. A negative id means the instruction
// has not been added to the graph.
int id_;
// When doing liveness analysis, instructions that have uses get an SSA index.
int ssa_index_;
// Packed fields.
uint32_t packed_fields_;
// List of instructions that have this instruction as input.
HUseList<HInstruction*> uses_;
// List of environments that contain this instruction.
HUseList<HEnvironment*> env_uses_;
// The environment associated with this instruction. Not null if the instruction
// might jump out of the method.
HEnvironment* environment_;
// Set by the code generator.
LocationSummary* locations_;
// Set by the liveness analysis.
LiveInterval* live_interval_;
// Set by the liveness analysis, this is the position in a linear
// order of blocks where this instruction's live interval start.
size_t lifetime_position_;
SideEffects side_effects_;
// The reference handle part of the reference type info.
// The IsExact() flag is stored in packed fields.
// TODO: for primitive types this should be marked as invalid.
ReferenceTypeInfo::TypeHandle reference_type_handle_;
friend class GraphChecker;
friend class HBasicBlock;
friend class HEnvironment;
friend class HGraph;
friend class HInstructionList;
std::ostream& operator<<(std::ostream& os, const HInstruction::InstructionKind& rhs);
// Iterates over the instructions, while preserving the next instruction
// in case the current instruction gets removed from the list by the user
// of this iterator.
class HInstructionIterator : public ValueObject {
explicit HInstructionIterator(const HInstructionList& instructions)
: instruction_(instructions.first_instruction_) {
next_ = Done() ? nullptr : instruction_->GetNext();