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sdk/runtime/vm/flow_graph_optimizer.cc
T
vegorov@google.com e1e7051b22 In LoadOptimizer::EmitPhis check for environment uses of phis. 
Previously we checked for input uses only. This caused some phis
to be not emitted if they had only environment uses. The bug was masked
by an elimination pass done before the register allocation.

R=kmillikin@google.com

Review URL: https://codereview.chromium.org//12391060

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@19390 260f80e4-7a28-3924-810f-c04153c831b5
2013-03-04 14:55:33 +00:00

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// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/flow_graph_optimizer.h"
#include "vm/bit_vector.h"
#include "vm/cha.h"
#include "vm/flow_graph_builder.h"
#include "vm/flow_graph_compiler.h"
#include "vm/hash_map.h"
#include "vm/il_printer.h"
#include "vm/intermediate_language.h"
#include "vm/object_store.h"
#include "vm/parser.h"
#include "vm/resolver.h"
#include "vm/scopes.h"
#include "vm/symbols.h"
namespace dart {
DECLARE_FLAG(bool, eliminate_type_checks);
DECLARE_FLAG(bool, enable_type_checks);
DEFINE_FLAG(bool, trace_optimization, false, "Print optimization details.");
DECLARE_FLAG(bool, trace_type_check_elimination);
DEFINE_FLAG(bool, use_cha, true, "Use class hierarchy analysis.");
DEFINE_FLAG(bool, load_cse, true, "Use redundant load elimination.");
DEFINE_FLAG(bool, trace_range_analysis, false, "Trace range analysis progress");
DEFINE_FLAG(bool, trace_constant_propagation, false,
"Print constant propagation and useless code elimination.");
DEFINE_FLAG(bool, array_bounds_check_elimination, true,
"Eliminate redundant bounds checks.");
DEFINE_FLAG(int, max_polymorphic_checks, 4,
"Maximum number of polymorphic check, otherwise it is megamorphic.");
DEFINE_FLAG(bool, remove_redundant_phis, true, "Remove redundant phis.");
DEFINE_FLAG(bool, truncating_left_shift, true,
"Optimize left shift to truncate if possible");
void FlowGraphOptimizer::ApplyICData() {
VisitBlocks();
}
// Attempts to convert an instance call (IC call) using propagated class-ids,
// e.g., receiver class id.
void FlowGraphOptimizer::ApplyClassIds() {
ASSERT(current_iterator_ == NULL);
for (intptr_t i = 0; i < block_order_.length(); ++i) {
BlockEntryInstr* entry = block_order_[i];
ForwardInstructionIterator it(entry);
current_iterator_ = &it;
for (; !it.Done(); it.Advance()) {
Instruction* instr = it.Current();
if (instr->IsInstanceCall()) {
InstanceCallInstr* call = instr->AsInstanceCall();
if (call->HasICData()) {
if (TryCreateICData(call)) {
VisitInstanceCall(call);
}
}
} else if (instr->IsPolymorphicInstanceCall()) {
SpecializePolymorphicInstanceCall(instr->AsPolymorphicInstanceCall());
} else if (instr->IsStrictCompare()) {
VisitStrictCompare(instr->AsStrictCompare());
} else if (instr->IsBranch()) {
ComparisonInstr* compare = instr->AsBranch()->comparison();
if (compare->IsStrictCompare()) {
VisitStrictCompare(compare->AsStrictCompare());
}
}
}
current_iterator_ = NULL;
}
}
// Attempt to build ICData for call using propagated class-ids.
bool FlowGraphOptimizer::TryCreateICData(InstanceCallInstr* call) {
ASSERT(call->HasICData());
if (call->ic_data()->NumberOfChecks() > 0) {
// This occurs when an instance call has too many checks.
// TODO(srdjan): Replace IC call with megamorphic call.
return false;
}
GrowableArray<intptr_t> class_ids(call->ic_data()->num_args_tested());
ASSERT(call->ic_data()->num_args_tested() <= call->ArgumentCount());
for (intptr_t i = 0; i < call->ic_data()->num_args_tested(); i++) {
intptr_t cid = call->PushArgumentAt(i)->value()->Type()->ToCid();
class_ids.Add(cid);
}
// TODO(srdjan): Test for other class_ids > 1.
if (class_ids.length() != 1) return false;
if (class_ids[0] != kDynamicCid) {
const intptr_t num_named_arguments = call->argument_names().IsNull() ?
0 : call->argument_names().Length();
const Class& receiver_class = Class::Handle(
Isolate::Current()->class_table()->At(class_ids[0]));
Function& function = Function::Handle();
function = Resolver::ResolveDynamicForReceiverClass(
receiver_class,
call->function_name(),
call->ArgumentCount(),
num_named_arguments);
if (function.IsNull()) {
return false;
}
// Create new ICData, do not modify the one attached to the instruction
// since it is attached to the assembly instruction itself.
// TODO(srdjan): Prevent modification of ICData object that is
// referenced in assembly code.
ICData& ic_data = ICData::ZoneHandle(ICData::New(
flow_graph_->parsed_function().function(),
call->function_name(),
call->deopt_id(),
class_ids.length()));
ic_data.AddReceiverCheck(class_ids[0], function);
call->set_ic_data(&ic_data);
return true;
}
return false;
}
static const ICData& SpecializeICData(const ICData& ic_data, intptr_t cid) {
ASSERT(ic_data.num_args_tested() == 1);
if ((ic_data.NumberOfChecks() == 1) &&
(ic_data.GetReceiverClassIdAt(0) == cid)) {
return ic_data; // Nothing to do
}
const ICData& new_ic_data = ICData::ZoneHandle(ICData::New(
Function::Handle(ic_data.function()),
String::Handle(ic_data.target_name()),
ic_data.deopt_id(),
ic_data.num_args_tested()));
const Function& function =
Function::Handle(ic_data.GetTargetForReceiverClassId(cid));
if (!function.IsNull()) {
new_ic_data.AddReceiverCheck(cid, function);
}
return new_ic_data;
}
void FlowGraphOptimizer::SpecializePolymorphicInstanceCall(
PolymorphicInstanceCallInstr* call) {
if (!call->with_checks()) {
return; // Already specialized.
}
const intptr_t receiver_cid =
call->PushArgumentAt(0)->value()->Type()->ToCid();
if (receiver_cid == kDynamicCid) {
return; // No information about receiver was infered.
}
const ICData& ic_data = SpecializeICData(call->ic_data(), receiver_cid);
const bool with_checks = false;
PolymorphicInstanceCallInstr* specialized =
new PolymorphicInstanceCallInstr(call->instance_call(),
ic_data,
with_checks);
call->ReplaceWith(specialized, current_iterator());
}
static BinarySmiOpInstr* AsSmiShiftLeftInstruction(Definition* d) {
BinarySmiOpInstr* instr = d->AsBinarySmiOp();
if ((instr != NULL) && (instr->op_kind() == Token::kSHL)) {
return instr;
}
return NULL;
}
static bool IsPositiveOrZeroSmiConst(Definition* d) {
ConstantInstr* const_instr = d->AsConstant();
if ((const_instr != NULL) && (const_instr->value().IsSmi())) {
return Smi::Cast(const_instr->value()).Value() >= 0;
}
return false;
}
void FlowGraphOptimizer::OptimizeLeftShiftBitAndSmiOp(
Definition* bit_and_instr,
Definition* left_instr,
Definition* right_instr) {
ASSERT(bit_and_instr != NULL);
ASSERT((left_instr != NULL) && (right_instr != NULL));
// Check for pattern, smi_shift_left must be single-use.
bool is_positive_or_zero = IsPositiveOrZeroSmiConst(left_instr);
if (!is_positive_or_zero) {
is_positive_or_zero = IsPositiveOrZeroSmiConst(right_instr);
}
if (!is_positive_or_zero) return;
BinarySmiOpInstr* smi_shift_left = NULL;
if (bit_and_instr->InputAt(0)->IsSingleUse()) {
smi_shift_left = AsSmiShiftLeftInstruction(left_instr);
}
if ((smi_shift_left == NULL) && (bit_and_instr->InputAt(1)->IsSingleUse())) {
smi_shift_left = AsSmiShiftLeftInstruction(right_instr);
}
if (smi_shift_left == NULL) return;
// Pattern recognized.
smi_shift_left->set_is_truncating(true);
ASSERT(bit_and_instr->IsBinarySmiOp() || bit_and_instr->IsBinaryMintOp());
if (bit_and_instr->IsBinaryMintOp()) {
// Replace Mint op with Smi op.
BinarySmiOpInstr* smi_op = new BinarySmiOpInstr(
Token::kBIT_AND,
bit_and_instr->AsBinaryMintOp()->instance_call(),
new Value(left_instr),
new Value(right_instr));
bit_and_instr->ReplaceWith(smi_op, current_iterator());
}
}
// Optimize (a << b) & c pattern: if c is a positive Smi or zero, then the
// shift can be a truncating Smi shift-left and result is always Smi.
void FlowGraphOptimizer::TryOptimizeLeftShiftWithBitAndPattern() {
if (!FLAG_truncating_left_shift) return;
ASSERT(current_iterator_ == NULL);
for (intptr_t i = 0; i < block_order_.length(); ++i) {
BlockEntryInstr* entry = block_order_[i];
ForwardInstructionIterator it(entry);
current_iterator_ = &it;
for (; !it.Done(); it.Advance()) {
if (it.Current()->IsBinarySmiOp()) {
BinarySmiOpInstr* binop = it.Current()->AsBinarySmiOp();
if (binop->op_kind() == Token::kBIT_AND) {
OptimizeLeftShiftBitAndSmiOp(binop,
binop->left()->definition(),
binop->right()->definition());
}
} else if (it.Current()->IsBinaryMintOp()) {
BinaryMintOpInstr* mintop = it.Current()->AsBinaryMintOp();
if (mintop->op_kind() == Token::kBIT_AND) {
OptimizeLeftShiftBitAndSmiOp(mintop,
mintop->left()->definition(),
mintop->right()->definition());
}
}
}
current_iterator_ = NULL;
}
}
static void EnsureSSATempIndex(FlowGraph* graph,
Definition* defn,
Definition* replacement) {
if ((replacement->ssa_temp_index() == -1) &&
(defn->ssa_temp_index() != -1)) {
replacement->set_ssa_temp_index(graph->alloc_ssa_temp_index());
}
}
static void ReplaceCurrentInstruction(ForwardInstructionIterator* iterator,
Instruction* current,
Instruction* replacement,
FlowGraph* graph) {
Definition* current_defn = current->AsDefinition();
if ((replacement != NULL) && (current_defn != NULL)) {
Definition* replacement_defn = replacement->AsDefinition();
ASSERT(replacement_defn != NULL);
current_defn->ReplaceUsesWith(replacement_defn);
EnsureSSATempIndex(graph, current_defn, replacement_defn);
if (FLAG_trace_optimization) {
OS::Print("Replacing v%"Pd" with v%"Pd"\n",
current_defn->ssa_temp_index(),
replacement_defn->ssa_temp_index());
}
} else if (FLAG_trace_optimization) {
if (current_defn == NULL) {
OS::Print("Removing %s\n", current->DebugName());
} else {
ASSERT(!current_defn->HasUses());
OS::Print("Removing v%"Pd".\n", current_defn->ssa_temp_index());
}
}
iterator->RemoveCurrentFromGraph();
}
void FlowGraphOptimizer::Canonicalize() {
for (intptr_t i = 0; i < block_order_.length(); ++i) {
BlockEntryInstr* entry = block_order_[i];
entry->Accept(this);
for (ForwardInstructionIterator it(entry); !it.Done(); it.Advance()) {
Instruction* current = it.Current();
Instruction* replacement = current->Canonicalize(this);
if (replacement != current) {
// For non-definitions Canonicalize should return either NULL or
// this.
ASSERT((replacement == NULL) || current->IsDefinition());
ReplaceCurrentInstruction(&it, current, replacement, flow_graph_);
}
}
}
}
void FlowGraphOptimizer::InsertConversion(Representation from,
Representation to,
Value* use,
Instruction* insert_before,
Instruction* deopt_target) {
Definition* converted = NULL;
if ((from == kTagged) && (to == kUnboxedMint)) {
ASSERT((deopt_target != NULL) ||
(use->Type()->ToCid() == kDoubleCid));
const intptr_t deopt_id = (deopt_target != NULL) ?
deopt_target->DeoptimizationTarget() : Isolate::kNoDeoptId;
converted = new UnboxIntegerInstr(use->CopyWithType(), deopt_id);
} else if ((from == kUnboxedMint) && (to == kTagged)) {
converted = new BoxIntegerInstr(use->CopyWithType());
} else if (from == kUnboxedMint && to == kUnboxedDouble) {
// Convert by boxing/unboxing.
// TODO(fschneider): Implement direct unboxed mint-to-double conversion.
BoxIntegerInstr* boxed = new BoxIntegerInstr(use->CopyWithType());
use->BindTo(boxed);
InsertBefore(insert_before, boxed, NULL, Definition::kValue);
const intptr_t deopt_id = (deopt_target != NULL) ?
deopt_target->DeoptimizationTarget() : Isolate::kNoDeoptId;
converted = new UnboxDoubleInstr(new Value(boxed), deopt_id);
} else if ((from == kUnboxedDouble) && (to == kTagged)) {
converted = new BoxDoubleInstr(use->CopyWithType(), NULL);
} else if ((from == kTagged) && (to == kUnboxedDouble)) {
ASSERT((deopt_target != NULL) ||
(use->Type()->ToCid() == kDoubleCid));
const intptr_t deopt_id = (deopt_target != NULL) ?
deopt_target->DeoptimizationTarget() : Isolate::kNoDeoptId;
ConstantInstr* constant = use->definition()->AsConstant();
if ((constant != NULL) && constant->value().IsSmi()) {
const double dbl_val = Smi::Cast(constant->value()).AsDoubleValue();
const Double& dbl_obj =
Double::ZoneHandle(Double::New(dbl_val, Heap::kOld));
ConstantInstr* double_const = new ConstantInstr(dbl_obj);
InsertBefore(insert_before, double_const, NULL, Definition::kValue);
converted = new UnboxDoubleInstr(new Value(double_const), deopt_id);
} else {
converted = new UnboxDoubleInstr(use->CopyWithType(), deopt_id);
}
}
ASSERT(converted != NULL);
use->BindTo(converted);
InsertBefore(insert_before, converted, use->instruction()->env(),
Definition::kValue);
}
void FlowGraphOptimizer::InsertConversionsFor(Definition* def) {
const Representation from_rep = def->representation();
for (Value::Iterator it(def->input_use_list());
!it.Done();
it.Advance()) {
Value* use = it.Current();
const Representation to_rep =
use->instruction()->RequiredInputRepresentation(use->use_index());
if (from_rep == to_rep) {
continue;
}
Instruction* insert_before;
Instruction* deopt_target;
PhiInstr* phi = use->instruction()->AsPhi();
if (phi != NULL) {
ASSERT(phi->is_alive());
// For phis conversions have to be inserted in the predecessor.
insert_before =
phi->block()->PredecessorAt(use->use_index())->last_instruction();
deopt_target = NULL;
} else {
deopt_target = insert_before = use->instruction();
}
InsertConversion(from_rep, to_rep, use, insert_before, deopt_target);
}
}
void FlowGraphOptimizer::SelectRepresentations() {
// Convervatively unbox all phis that were proven to be of type Double.
for (intptr_t i = 0; i < block_order_.length(); ++i) {
JoinEntryInstr* join_entry = block_order_[i]->AsJoinEntry();
if (join_entry != NULL) {
for (PhiIterator it(join_entry); !it.Done(); it.Advance()) {
PhiInstr* phi = it.Current();
ASSERT(phi != NULL);
if (phi->Type()->ToCid() == kDoubleCid) {
phi->set_representation(kUnboxedDouble);
}
}
}
}
// Process all instructions and insert conversions where needed.
GraphEntryInstr* graph_entry = block_order_[0]->AsGraphEntry();
// Visit incoming parameters and constants.
for (intptr_t i = 0; i < graph_entry->initial_definitions()->length(); i++) {
InsertConversionsFor((*graph_entry->initial_definitions())[i]);
}
for (intptr_t i = 0; i < block_order_.length(); ++i) {
BlockEntryInstr* entry = block_order_[i];
JoinEntryInstr* join_entry = entry->AsJoinEntry();
if (join_entry != NULL) {
for (PhiIterator it(join_entry); !it.Done(); it.Advance()) {
PhiInstr* phi = it.Current();
ASSERT(phi != NULL);
ASSERT(phi->is_alive());
InsertConversionsFor(phi);
}
}
for (ForwardInstructionIterator it(entry); !it.Done(); it.Advance()) {
Definition* def = it.Current()->AsDefinition();
if (def != NULL) {
InsertConversionsFor(def);
}
}
}
}
static bool ICDataHasReceiverArgumentClassIds(const ICData& ic_data,
intptr_t receiver_class_id,
intptr_t argument_class_id) {
ASSERT(receiver_class_id != kIllegalCid);
ASSERT(argument_class_id != kIllegalCid);
if (ic_data.num_args_tested() != 2) return false;
Function& target = Function::Handle();
const intptr_t len = ic_data.NumberOfChecks();
for (intptr_t i = 0; i < len; i++) {
GrowableArray<intptr_t> class_ids;
ic_data.GetCheckAt(i, &class_ids, &target);
ASSERT(class_ids.length() == 2);
if ((class_ids[0] == receiver_class_id) &&
(class_ids[1] == argument_class_id)) {
return true;
}
}
return false;
}
static bool ClassIdIsOneOf(intptr_t class_id,
const GrowableArray<intptr_t>& class_ids) {
for (intptr_t i = 0; i < class_ids.length(); i++) {
if (class_ids[i] == class_id) {
return true;
}
}
return false;
}
// Returns true if ICData tests two arguments and all ICData cids are in the
// required sets 'receiver_class_ids' or 'argument_class_ids', respectively.
static bool ICDataHasOnlyReceiverArgumentClassIds(
const ICData& ic_data,
const GrowableArray<intptr_t>& receiver_class_ids,
const GrowableArray<intptr_t>& argument_class_ids) {
if (ic_data.num_args_tested() != 2) return false;
Function& target = Function::Handle();
const intptr_t len = ic_data.NumberOfChecks();
for (intptr_t i = 0; i < len; i++) {
GrowableArray<intptr_t> class_ids;
ic_data.GetCheckAt(i, &class_ids, &target);
ASSERT(class_ids.length() == 2);
if (!ClassIdIsOneOf(class_ids[0], receiver_class_ids) ||
!ClassIdIsOneOf(class_ids[1], argument_class_ids)) {
return false;
}
}
return true;
}
static bool HasOnlyOneSmi(const ICData& ic_data) {
return (ic_data.NumberOfChecks() == 1)
&& ic_data.HasReceiverClassId(kSmiCid);
}
static bool HasOnlySmiOrMint(const ICData& ic_data) {
if (ic_data.NumberOfChecks() == 1) {
return ic_data.HasReceiverClassId(kSmiCid)
|| ic_data.HasReceiverClassId(kMintCid);
}
return (ic_data.NumberOfChecks() == 2)
&& ic_data.HasReceiverClassId(kSmiCid)
&& ic_data.HasReceiverClassId(kMintCid);
}
static bool HasOnlyTwoSmis(const ICData& ic_data) {
return (ic_data.NumberOfChecks() == 1) &&
ICDataHasReceiverArgumentClassIds(ic_data, kSmiCid, kSmiCid);
}
// Returns false if the ICData contains anything other than the 4 combinations
// of Mint and Smi for the receiver and argument classes.
static bool HasTwoMintOrSmi(const ICData& ic_data) {
GrowableArray<intptr_t> class_ids(2);
class_ids.Add(kSmiCid);
class_ids.Add(kMintCid);
return ICDataHasOnlyReceiverArgumentClassIds(ic_data, class_ids, class_ids);
}
static bool HasOnlyOneDouble(const ICData& ic_data) {
return (ic_data.NumberOfChecks() == 1)
&& ic_data.HasReceiverClassId(kDoubleCid);
}
static bool ShouldSpecializeForDouble(const ICData& ic_data) {
// Unboxed double operation can't handle case of two smis.
if (ICDataHasReceiverArgumentClassIds(ic_data, kSmiCid, kSmiCid)) {
return false;
}
// Check that it have seen only smis and doubles.
GrowableArray<intptr_t> class_ids(2);
class_ids.Add(kSmiCid);
class_ids.Add(kDoubleCid);
return ICDataHasOnlyReceiverArgumentClassIds(ic_data, class_ids, class_ids);
}
void FlowGraphOptimizer::ReplaceCall(Definition* call,
Definition* replacement) {
// Remove the original push arguments.
for (intptr_t i = 0; i < call->ArgumentCount(); ++i) {
PushArgumentInstr* push = call->PushArgumentAt(i);
push->ReplaceUsesWith(push->value()->definition());
push->RemoveFromGraph();
}
call->ReplaceWith(replacement, current_iterator());
}
static intptr_t ReceiverClassId(InstanceCallInstr* call) {
if (!call->HasICData()) return kIllegalCid;
const ICData& ic_data = ICData::Handle(call->ic_data()->AsUnaryClassChecks());
if (ic_data.NumberOfChecks() == 0) return kIllegalCid;
// TODO(vegorov): Add multiple receiver type support.
if (ic_data.NumberOfChecks() != 1) return kIllegalCid;
ASSERT(ic_data.HasOneTarget());
Function& target = Function::Handle();
intptr_t class_id;
ic_data.GetOneClassCheckAt(0, &class_id, &target);
return class_id;
}
void FlowGraphOptimizer::AddCheckSmi(Definition* to_check,
intptr_t deopt_id,
Environment* deopt_environment,
Instruction* insert_before) {
if (to_check->Type()->ToCid() != kSmiCid) {
InsertBefore(insert_before,
new CheckSmiInstr(new Value(to_check), deopt_id),
deopt_environment,
Definition::kEffect);
}
}
void FlowGraphOptimizer::AddCheckClass(Definition* to_check,
const ICData& unary_checks,
intptr_t deopt_id,
Environment* deopt_environment,
Instruction* insert_before) {
// Type propagation has not run yet, we cannot eliminate the check.
Instruction* check = NULL;
if ((unary_checks.NumberOfChecks() == 1) &&
(unary_checks.GetReceiverClassIdAt(0) == kSmiCid)) {
check = new CheckSmiInstr(new Value(to_check), deopt_id);
} else {
check = new CheckClassInstr(new Value(to_check), deopt_id, unary_checks);
}
InsertBefore(insert_before, check, deopt_environment, Definition::kEffect);
}
void FlowGraphOptimizer::AddReceiverCheck(InstanceCallInstr* call) {
AddCheckClass(call->ArgumentAt(0),
ICData::ZoneHandle(call->ic_data()->AsUnaryClassChecks()),
call->deopt_id(),
call->env(),
call);
}
static bool ArgIsAlwaysSmi(const ICData& ic_data, intptr_t arg_n) {
ASSERT(ic_data.num_args_tested() > arg_n);
if (ic_data.NumberOfChecks() == 0) return false;
GrowableArray<intptr_t> class_ids;
Function& target = Function::Handle();
const intptr_t len = ic_data.NumberOfChecks();
for (intptr_t i = 0; i < len; i++) {
ic_data.GetCheckAt(i, &class_ids, &target);
if (class_ids[arg_n] != kSmiCid) return false;
}
return true;
}
// Returns array classid to load from, array and index value
intptr_t FlowGraphOptimizer::PrepareIndexedOp(InstanceCallInstr* call,
intptr_t class_id,
Definition** array,
Definition** index) {
// Insert class check and index smi checks and attach a copy of the
// original environment because the operation can still deoptimize.
AddReceiverCheck(call);
InsertBefore(call,
new CheckSmiInstr(new Value(*index), call->deopt_id()),
call->env(),
Definition::kEffect);
// If both index and array are constants, then do a compile-time check.
// TODO(srdjan): Remove once constant propagation handles bounds checks.
bool skip_check = false;
if ((*array)->IsConstant() && (*index)->IsConstant()) {
const ImmutableArray& constant_array =
ImmutableArray::Cast((*array)->AsConstant()->value());
const Object& constant_index = (*index)->AsConstant()->value();
skip_check = constant_index.IsSmi() &&
(Smi::Cast(constant_index).Value() < constant_array.Length());
}
if (!skip_check) {
// Insert array length load and bounds check.
const bool is_immutable =
CheckArrayBoundInstr::IsFixedLengthArrayType(class_id);
LoadFieldInstr* length =
new LoadFieldInstr(new Value(*array),
CheckArrayBoundInstr::LengthOffsetFor(class_id),
Type::ZoneHandle(Type::SmiType()),
is_immutable);
length->set_result_cid(kSmiCid);
length->set_recognized_kind(
LoadFieldInstr::RecognizedKindFromArrayCid(class_id));
InsertBefore(call, length, NULL, Definition::kValue);
InsertBefore(call,
new CheckArrayBoundInstr(new Value(length),
new Value(*index),
class_id,
call),
call->env(),
Definition::kEffect);
}
if (class_id == kGrowableObjectArrayCid) {
// Insert data elements load.
LoadFieldInstr* elements =
new LoadFieldInstr(new Value(*array),
GrowableObjectArray::data_offset(),
Type::ZoneHandle(Type::DynamicType()));
elements->set_result_cid(kArrayCid);
InsertBefore(call, elements, NULL, Definition::kValue);
*array = elements;
return kArrayCid;
}
return class_id;
}
bool FlowGraphOptimizer::TryReplaceWithStoreIndexed(InstanceCallInstr* call) {
const intptr_t class_id = ReceiverClassId(call);
ICData& value_check = ICData::ZoneHandle();
switch (class_id) {
case kArrayCid:
case kGrowableObjectArrayCid:
if (ArgIsAlwaysSmi(*call->ic_data(), 2)) {
value_check = call->ic_data()->AsUnaryClassChecksForArgNr(2);
}
break;
case kInt8ArrayCid:
case kUint8ArrayCid:
case kUint8ClampedArrayCid:
case kExternalUint8ArrayCid:
case kExternalUint8ClampedArrayCid:
case kInt16ArrayCid:
case kUint16ArrayCid:
// Check that value is always smi.
value_check = call->ic_data()->AsUnaryClassChecksForArgNr(2);
if ((value_check.NumberOfChecks() != 1) ||
(value_check.GetReceiverClassIdAt(0) != kSmiCid)) {
return false;
}
break;
case kInt32ArrayCid:
case kUint32ArrayCid: {
// Check if elements fit into a smi or the platform supports unboxed
// mints.
if ((kSmiBits < 32) && !FlowGraphCompiler::SupportsUnboxedMints()) {
return false;
}
// Check that value is always smi or mint, if the platform has unboxed
// mints (ia32 with at least SSE 4.1).
value_check = call->ic_data()->AsUnaryClassChecksForArgNr(2);
for (intptr_t i = 0; i < value_check.NumberOfChecks(); i++) {
intptr_t cid = value_check.GetReceiverClassIdAt(i);
if (FlowGraphCompiler::SupportsUnboxedMints()) {
if ((cid != kSmiCid) && (cid != kMintCid)) {
return false;
}
} else if (cid != kSmiCid) {
return false;
}
}
break;
}
case kFloat32ArrayCid:
case kFloat64ArrayCid: {
// Check that value is always double.
value_check = call->ic_data()->AsUnaryClassChecksForArgNr(2);
if ((value_check.NumberOfChecks() != 1) ||
(value_check.GetReceiverClassIdAt(0) != kDoubleCid)) {
return false;
}
break;
}
default:
// TODO(fschneider): Add support for other array types.
return false;
}
BuildStoreIndexed(call, value_check, class_id);
return true;
}
bool FlowGraphOptimizer::TryInlineByteArraySetIndexed(InstanceCallInstr* call) {
const intptr_t class_id = ReceiverClassId(call);
ICData& value_check = ICData::ZoneHandle();
switch (class_id) {
case kInt8ArrayCid:
case kUint8ArrayCid:
case kUint8ClampedArrayCid:
case kExternalUint8ArrayCid:
case kExternalUint8ClampedArrayCid:
case kInt16ArrayCid:
case kUint16ArrayCid: {
// Check that value is always smi.
value_check = ICData::New(Function::Handle(),
String::Handle(),
Isolate::kNoDeoptId,
1);
value_check.AddReceiverCheck(kSmiCid, Function::Handle());
break;
}
case kInt32ArrayCid:
case kUint32ArrayCid:
// Check if elements fit into a smi or the platform supports unboxed
// mints.
if ((kSmiBits < 32) && !FlowGraphCompiler::SupportsUnboxedMints()) {
return false;
}
// We don't have ICData for the value stored, so we optimistically assume
// smis first. If we ever deoptimized here, we require to unbox the value
// before storing to handle the mint case, too.
if (call->ic_data()->deopt_reason() == kDeoptUnknown) {
value_check = ICData::New(Function::Handle(),
String::Handle(),
Isolate::kNoDeoptId,
1);
value_check.AddReceiverCheck(kSmiCid, Function::Handle());
}
break;
case kFloat32ArrayCid:
case kFloat64ArrayCid: {
// Check that value is always double.
value_check = ICData::New(Function::Handle(),
String::Handle(),
Isolate::kNoDeoptId,
1);
value_check.AddReceiverCheck(kDoubleCid, Function::Handle());
break;
}
default:
return false;
}
BuildStoreIndexed(call, value_check, class_id);
return true;
}
void FlowGraphOptimizer::BuildStoreIndexed(InstanceCallInstr* call,
const ICData& value_check,
intptr_t class_id) {
Definition* array = call->ArgumentAt(0);
Definition* index = call->ArgumentAt(1);
Definition* stored_value = call->ArgumentAt(2);
if (FLAG_enable_type_checks) {
// Only type check for the value. A type check for the index is not
// needed here because we insert a deoptimizing smi-check for the case
// the index is not a smi.
const Function& target =
Function::ZoneHandle(call->ic_data()->GetTargetAt(0));
const AbstractType& value_type =
AbstractType::ZoneHandle(target.ParameterTypeAt(2));
Definition* instantiator = NULL;
Definition* type_args = NULL;
switch (class_id) {
case kArrayCid:
case kGrowableObjectArrayCid: {
const Class& instantiator_class = Class::Handle(target.Owner());
intptr_t type_arguments_field_offset =
instantiator_class.type_arguments_field_offset();
LoadFieldInstr* load_type_args =
new LoadFieldInstr(new Value(array),
type_arguments_field_offset,
Type::ZoneHandle()); // No type.
InsertBefore(call, load_type_args, NULL, Definition::kValue);
instantiator = array;
type_args = load_type_args;
break;
}
case kInt8ArrayCid:
case kUint8ArrayCid:
case kUint8ClampedArrayCid:
case kExternalUint8ArrayCid:
case kExternalUint8ClampedArrayCid:
case kInt16ArrayCid:
case kUint16ArrayCid:
case kInt32ArrayCid:
case kUint32ArrayCid:
ASSERT(value_type.IsIntType());
// Fall through.
case kFloat32ArrayCid:
case kFloat64ArrayCid: {
type_args = instantiator = flow_graph_->constant_null();
ASSERT((class_id != kFloat32ArrayCid && class_id != kFloat64ArrayCid) ||
value_type.IsDoubleType());
ASSERT(value_type.IsInstantiated());
break;
}
default:
// TODO(fschneider): Add support for other array types.
UNREACHABLE();
}
AssertAssignableInstr* assert_value =
new AssertAssignableInstr(call->token_pos(),
new Value(stored_value),
new Value(instantiator),
new Value(type_args),
value_type,
Symbols::Value());
// Newly inserted instructions that can deoptimize or throw an exception
// must have a deoptimization id that is valid for lookup in the unoptimized
// code.
assert_value->deopt_id_ = call->deopt_id();
InsertBefore(call, assert_value, call->env(), Definition::kValue);
}
intptr_t array_cid = PrepareIndexedOp(call, class_id, &array, &index);
// Check if store barrier is needed. Byte arrays don't need a store barrier.
StoreBarrierType needs_store_barrier =
RawObject::IsByteArrayClassId(array_cid)
? kNoStoreBarrier
: kEmitStoreBarrier;
if (!value_check.IsNull()) {
// No store barrier needed because checked value is a smi, an unboxed mint
// or unboxed double.
needs_store_barrier = kNoStoreBarrier;
AddCheckClass(stored_value, value_check, call->deopt_id(), call->env(),
call);
}
Definition* array_op = new StoreIndexedInstr(new Value(array),
new Value(index),
new Value(stored_value),
needs_store_barrier,
array_cid,
call->deopt_id());
ReplaceCall(call, array_op);
}
bool FlowGraphOptimizer::TryReplaceWithLoadIndexed(InstanceCallInstr* call) {
const intptr_t class_id = ReceiverClassId(call);
// Set deopt_id to a valid id if the LoadIndexedInstr can cause deopt.
intptr_t deopt_id = Isolate::kNoDeoptId;
switch (class_id) {
case kArrayCid:
case kImmutableArrayCid:
case kGrowableObjectArrayCid:
case kFloat32ArrayCid:
case kFloat64ArrayCid:
case kInt8ArrayCid:
case kUint8ArrayCid:
case kUint8ClampedArrayCid:
case kExternalUint8ArrayCid:
case kExternalUint8ClampedArrayCid:
case kInt16ArrayCid:
case kUint16ArrayCid:
break;
case kInt32ArrayCid:
case kUint32ArrayCid:
// Check if elements fit into a smi or the platform supports unboxed
// mints.
if ((kSmiBits < 32) && !FlowGraphCompiler::SupportsUnboxedMints()) {
return false;
}
{
// Set deopt_id if we can optimistically assume that the result is Smi.
// Assume mixed Mint/Smi if this instruction caused deoptimization once.
ASSERT(call->HasICData());
const ICData& ic_data = *call->ic_data();
deopt_id = (ic_data.deopt_reason() == kDeoptUnknown) ?
call->deopt_id() : Isolate::kNoDeoptId;
}
break;
default:
return false;
}
Definition* array = call->ArgumentAt(0);
Definition* index = call->ArgumentAt(1);
intptr_t array_cid = PrepareIndexedOp(call, class_id, &array, &index);
Definition* array_op =
new LoadIndexedInstr(new Value(array),
new Value(index),
FlowGraphCompiler::ElementSizeFor(array_cid),
array_cid,
deopt_id);
ReplaceCall(call, array_op);
return true;
}
bool FlowGraphOptimizer::TryReplaceWithBinaryOp(InstanceCallInstr* call,
Token::Kind op_kind) {
intptr_t operands_type = kIllegalCid;
ASSERT(call->HasICData());
const ICData& ic_data = *call->ic_data();
switch (op_kind) {
case Token::kADD:
case Token::kSUB:
if (HasOnlyTwoSmis(ic_data)) {
// Don't generate smi code if the IC data is marked because
// of an overflow.
operands_type = (ic_data.deopt_reason() == kDeoptBinarySmiOp)
? kMintCid
: kSmiCid;
} else if (HasTwoMintOrSmi(ic_data) &&
FlowGraphCompiler::SupportsUnboxedMints()) {
// Don't generate mint code if the IC data is marked because of an
// overflow.
if (ic_data.deopt_reason() == kDeoptBinaryMintOp) return false;
operands_type = kMintCid;
} else if (ShouldSpecializeForDouble(ic_data)) {
operands_type = kDoubleCid;
} else {
return false;
}
break;
case Token::kMUL:
if (HasOnlyTwoSmis(ic_data)) {
// Don't generate smi code if the IC data is marked because of an
// overflow.
// TODO(fschneider): Add unboxed mint multiplication.
if (ic_data.deopt_reason() == kDeoptBinarySmiOp) return false;
operands_type = kSmiCid;
} else if (ShouldSpecializeForDouble(ic_data)) {
operands_type = kDoubleCid;
} else {
return false;
}
break;
case Token::kDIV:
if (ShouldSpecializeForDouble(ic_data)) {
operands_type = kDoubleCid;
} else {
return false;
}
break;
case Token::kMOD:
if (HasOnlyTwoSmis(ic_data)) {
operands_type = kSmiCid;
} else {
return false;
}
break;
case Token::kBIT_AND:
case Token::kBIT_OR:
case Token::kBIT_XOR:
if (HasOnlyTwoSmis(ic_data)) {
operands_type = kSmiCid;
} else if (HasTwoMintOrSmi(ic_data)) {
operands_type = kMintCid;
} else {
return false;
}
break;
case Token::kSHR:
case Token::kSHL:
if (HasOnlyTwoSmis(ic_data)) {
// Left shift may overflow from smi into mint or big ints.
// Don't generate smi code if the IC data is marked because
// of an overflow.
if (ic_data.deopt_reason() == kDeoptShiftMintOp) return false;
operands_type = (ic_data.deopt_reason() == kDeoptBinarySmiOp)
? kMintCid
: kSmiCid;
} else if (HasTwoMintOrSmi(ic_data) &&
HasOnlyOneSmi(ICData::Handle(
ic_data.AsUnaryClassChecksForArgNr(1)))) {
// Don't generate mint code if the IC data is marked because of an
// overflow.
if (ic_data.deopt_reason() == kDeoptShiftMintOp) return false;
// Check for smi/mint << smi or smi/mint >> smi.
operands_type = kMintCid;
} else {
return false;
}
break;
case Token::kTRUNCDIV:
if (HasOnlyTwoSmis(ic_data)) {
if (ic_data.deopt_reason() == kDeoptBinarySmiOp) return false;
operands_type = kSmiCid;
} else {
return false;
}
break;
default:
UNREACHABLE();
}
ASSERT(call->ArgumentCount() == 2);
Definition* left = call->ArgumentAt(0);
Definition* right = call->ArgumentAt(1);
if (operands_type == kDoubleCid) {
// Check that either left or right are not a smi. Result of a
// binary operation with two smis is a smi not a double.
InsertBefore(call,
new CheckEitherNonSmiInstr(new Value(left),
new Value(right),
call),
call->env(),
Definition::kEffect);
BinaryDoubleOpInstr* double_bin_op =
new BinaryDoubleOpInstr(op_kind, new Value(left), new Value(right),
call);
ReplaceCall(call, double_bin_op);
} else if (operands_type == kMintCid) {
if (!FlowGraphCompiler::SupportsUnboxedMints()) return false;
if ((op_kind == Token::kSHR) || (op_kind == Token::kSHL)) {
ShiftMintOpInstr* shift_op =
new ShiftMintOpInstr(op_kind, new Value(left), new Value(right),
call);
ReplaceCall(call, shift_op);
} else {
BinaryMintOpInstr* bin_op =
new BinaryMintOpInstr(op_kind, new Value(left), new Value(right),
call);
ReplaceCall(call, bin_op);
}
} else if (op_kind == Token::kMOD) {
// TODO(vegorov): implement fast path code for modulo.
ASSERT(operands_type == kSmiCid);
if (!right->IsConstant()) return false;
const Object& obj = right->AsConstant()->value();
if (!obj.IsSmi()) return false;
const intptr_t value = Smi::Cast(obj).Value();
if ((value <= 0) || !Utils::IsPowerOfTwo(value)) return false;
// Insert smi check and attach a copy of the original environment
// because the smi operation can still deoptimize.
InsertBefore(call,
new CheckSmiInstr(new Value(left), call->deopt_id()),
call->env(),
Definition::kEffect);
ConstantInstr* constant =
new ConstantInstr(Smi::Handle(Smi::New(value - 1)));
InsertBefore(call, constant, NULL, Definition::kValue);
BinarySmiOpInstr* bin_op =
new BinarySmiOpInstr(Token::kBIT_AND, call,
new Value(left),
new Value(constant));
ReplaceCall(call, bin_op);
} else {
ASSERT(operands_type == kSmiCid);
// Insert two smi checks and attach a copy of the original
// environment because the smi operation can still deoptimize.
AddCheckSmi(left, call->deopt_id(), call->env(), call);
AddCheckSmi(right, call->deopt_id(), call->env(), call);
if (left->IsConstant() &&
((op_kind == Token::kADD) || (op_kind == Token::kMUL))) {
// Constant should be on the right side.
Definition* temp = left;
left = right;
right = temp;
}
BinarySmiOpInstr* bin_op =
new BinarySmiOpInstr(op_kind, call, new Value(left), new Value(right));
ReplaceCall(call, bin_op);
}
return true;
}
bool FlowGraphOptimizer::TryReplaceWithUnaryOp(InstanceCallInstr* call,
Token::Kind op_kind) {
ASSERT(call->ArgumentCount() == 1);
Definition* input = call->ArgumentAt(0);
Definition* unary_op = NULL;
if (HasOnlyOneSmi(*call->ic_data())) {
InsertBefore(call,
new CheckSmiInstr(new Value(input), call->deopt_id()),
call->env(),
Definition::kEffect);
unary_op = new UnarySmiOpInstr(op_kind, call, new Value(input));
} else if ((op_kind == Token::kBIT_NOT) &&
HasOnlySmiOrMint(*call->ic_data()) &&
FlowGraphCompiler::SupportsUnboxedMints()) {
unary_op = new UnaryMintOpInstr(op_kind, new Value(input), call);
} else if (HasOnlyOneDouble(*call->ic_data()) &&
(op_kind == Token::kNEGATE)) {
AddReceiverCheck(call);
ConstantInstr* minus_one =
new ConstantInstr(Double::ZoneHandle(Double::NewCanonical(-1)));
InsertBefore(call, minus_one, NULL, Definition::kValue);
unary_op = new BinaryDoubleOpInstr(Token::kMUL,
new Value(input),
new Value(minus_one),
call);
}
if (unary_op == NULL) return false;
ReplaceCall(call, unary_op);
return true;
}
// Using field class
static RawField* GetField(intptr_t class_id, const String& field_name) {
Class& cls = Class::Handle(Isolate::Current()->class_table()->At(class_id));
Field& field = Field::Handle();
while (!cls.IsNull()) {
field = cls.LookupInstanceField(field_name);
if (!field.IsNull()) {
return field.raw();
}
cls = cls.SuperClass();
}
return Field::null();
}
// Use CHA to determine if the call needs a class check: if the callee's
// receiver is the same as the caller's receiver and there are no overriden
// callee functions, then no class check is needed.
bool FlowGraphOptimizer::InstanceCallNeedsClassCheck(
InstanceCallInstr* call) const {
if (!FLAG_use_cha) return true;
Definition* callee_receiver = call->ArgumentAt(0);
ASSERT(callee_receiver != NULL);
const Function& function = flow_graph_->parsed_function().function();
if (function.IsDynamicFunction() &&
callee_receiver->IsParameter() &&
(callee_receiver->AsParameter()->index() == 0)) {
return CHA::HasOverride(Class::Handle(function.Owner()),
call->function_name());
}
return true;
}
bool FlowGraphOptimizer::MethodExtractorNeedsClassCheck(
InstanceCallInstr* call) const {
if (!FLAG_use_cha) return true;
Definition* callee_receiver = call->ArgumentAt(0);
ASSERT(callee_receiver != NULL);
const Function& function = flow_graph_->parsed_function().function();
if (function.IsDynamicFunction() &&
callee_receiver->IsParameter() &&
(callee_receiver->AsParameter()->index() == 0)) {
const String& field_name =
String::Handle(Field::NameFromGetter(call->function_name()));
return CHA::HasOverride(Class::Handle(function.Owner()), field_name);
}
return true;
}
void FlowGraphOptimizer::InlineImplicitInstanceGetter(InstanceCallInstr* call) {
ASSERT(call->HasICData());
const ICData& ic_data = *call->ic_data();
Function& target = Function::Handle();
GrowableArray<intptr_t> class_ids;
ic_data.GetCheckAt(0, &class_ids, &target);
ASSERT(class_ids.length() == 1);
// Inline implicit instance getter.
const String& field_name =
String::Handle(Field::NameFromGetter(call->function_name()));
const Field& field = Field::Handle(GetField(class_ids[0], field_name));
ASSERT(!field.IsNull());
if (InstanceCallNeedsClassCheck(call)) {
AddReceiverCheck(call);
}
LoadFieldInstr* load = new LoadFieldInstr(
new Value(call->ArgumentAt(0)),
field.Offset(),
AbstractType::ZoneHandle(field.type()),
field.is_final());
// Discard the environment from the original instruction because the load
// can't deoptimize.
call->RemoveEnvironment();
ReplaceCall(call, load);
}
void FlowGraphOptimizer::InlineArrayLengthGetter(InstanceCallInstr* call,
intptr_t length_offset,
bool is_immutable,
MethodRecognizer::Kind kind) {
AddReceiverCheck(call);
LoadFieldInstr* load = new LoadFieldInstr(
new Value(call->ArgumentAt(0)),
length_offset,
Type::ZoneHandle(Type::SmiType()),
is_immutable);
load->set_result_cid(kSmiCid);
load->set_recognized_kind(kind);
ReplaceCall(call, load);
}
void FlowGraphOptimizer::InlineGrowableArrayCapacityGetter(
InstanceCallInstr* call) {
AddReceiverCheck(call);
// TODO(srdjan): type of load should be GrowableObjectArrayType.
LoadFieldInstr* data_load = new LoadFieldInstr(
new Value(call->ArgumentAt(0)),
Array::data_offset(),
Type::ZoneHandle(Type::DynamicType()));
data_load->set_result_cid(kArrayCid);
InsertBefore(call, data_load, NULL, Definition::kValue);
LoadFieldInstr* length_load = new LoadFieldInstr(
new Value(data_load),
Array::length_offset(),
Type::ZoneHandle(Type::SmiType()));
length_load->set_result_cid(kSmiCid);
length_load->set_recognized_kind(MethodRecognizer::kObjectArrayLength);
ReplaceCall(call, length_load);
}
static LoadFieldInstr* BuildLoadStringLength(Definition* str) {
// Treat length loads as mutable (i.e. affected by side effects) to avoid
// hoisting them since we can't hoist the preceding class-check. This
// is because of externalization of strings that affects their class-id.
const bool is_immutable = false;
LoadFieldInstr* load = new LoadFieldInstr(
new Value(str),
String::length_offset(),
Type::ZoneHandle(Type::SmiType()),
is_immutable);
load->set_result_cid(kSmiCid);
load->set_recognized_kind(MethodRecognizer::kStringBaseLength);
return load;
}
void FlowGraphOptimizer::InlineStringLengthGetter(InstanceCallInstr* call) {
AddReceiverCheck(call);
LoadFieldInstr* load = BuildLoadStringLength(call->ArgumentAt(0));
ReplaceCall(call, load);
}
void FlowGraphOptimizer::InlineStringIsEmptyGetter(InstanceCallInstr* call) {
AddReceiverCheck(call);
LoadFieldInstr* load = BuildLoadStringLength(call->ArgumentAt(0));
InsertBefore(call, load, NULL, Definition::kValue);
ConstantInstr* zero = new ConstantInstr(Smi::Handle(Smi::New(0)));
InsertBefore(call, zero, NULL, Definition::kValue);
StrictCompareInstr* compare =
new StrictCompareInstr(Token::kEQ_STRICT,
new Value(load),
new Value(zero));
ReplaceCall(call, compare);
}
static intptr_t OffsetForLengthGetter(MethodRecognizer::Kind kind) {
switch (kind) {
case MethodRecognizer::kObjectArrayLength:
case MethodRecognizer::kImmutableArrayLength:
return Array::length_offset();
case MethodRecognizer::kByteArrayBaseLength:
return ByteArray::length_offset();
case MethodRecognizer::kGrowableArrayLength:
return GrowableObjectArray::length_offset();
default:
UNREACHABLE();
return 0;
}
}
// Only unique implicit instance getters can be currently handled.
bool FlowGraphOptimizer::TryInlineInstanceGetter(InstanceCallInstr* call) {
ASSERT(call->HasICData());
const ICData& ic_data = *call->ic_data();
if (ic_data.NumberOfChecks() == 0) {
// No type feedback collected.
return false;
}
Function& target = Function::Handle(ic_data.GetTargetAt(0));
if (target.kind() == RawFunction::kImplicitGetter) {
if (!ic_data.HasOneTarget()) {
// TODO(srdjan): Implement for mutiple targets.
return false;
}
InlineImplicitInstanceGetter(call);
return true;
} else if (target.kind() == RawFunction::kMethodExtractor) {
return false;
}
// Not an implicit getter.
MethodRecognizer::Kind recognized_kind =
MethodRecognizer::RecognizeKind(target);
// VM objects length getter.
switch (recognized_kind) {
case MethodRecognizer::kObjectArrayLength:
case MethodRecognizer::kImmutableArrayLength:
case MethodRecognizer::kByteArrayBaseLength:
case MethodRecognizer::kGrowableArrayLength: {
if (!ic_data.HasOneTarget()) {
// TODO(srdjan): Implement for mutiple targets.
return false;
}
const bool is_immutable =
(recognized_kind == MethodRecognizer::kObjectArrayLength) ||
(recognized_kind == MethodRecognizer::kImmutableArrayLength) ||
(recognized_kind == MethodRecognizer::kByteArrayBaseLength);
InlineArrayLengthGetter(call,
OffsetForLengthGetter(recognized_kind),
is_immutable,
recognized_kind);
return true;
}
case MethodRecognizer::kGrowableArrayCapacity:
InlineGrowableArrayCapacityGetter(call);
return true;
case MethodRecognizer::kStringBaseLength:
if (!ic_data.HasOneTarget()) {
// Target is not only StringBase_get_length.
return false;
}
InlineStringLengthGetter(call);
return true;
case MethodRecognizer::kStringBaseIsEmpty:
if (!ic_data.HasOneTarget()) {
// Target is not only StringBase_get_isEmpty.
return false;
}
InlineStringIsEmptyGetter(call);
return true;
default:
ASSERT(recognized_kind == MethodRecognizer::kUnknown);
}
return false;
}
LoadIndexedInstr* FlowGraphOptimizer::BuildStringCodeUnitAt(
InstanceCallInstr* call,
intptr_t cid) {
Definition* str = call->ArgumentAt(0);
Definition* index = call->ArgumentAt(1);
AddReceiverCheck(call);
InsertBefore(call,
new CheckSmiInstr(new Value(index), call->deopt_id()),
call->env(),
Definition::kEffect);
// If both index and string are constants, then do a compile-time check.
// TODO(srdjan): Remove once constant propagation handles bounds checks.
bool skip_check = false;
if (str->IsConstant() && index->IsConstant()) {
const String& constant_string =
String::Cast(str->AsConstant()->value());
const Object& constant_index = index->AsConstant()->value();
skip_check = constant_index.IsSmi() &&
(Smi::Cast(constant_index).Value() < constant_string.Length());
}
if (!skip_check) {
// Insert bounds check.
LoadFieldInstr* length = BuildLoadStringLength(str);
InsertBefore(call, length, NULL, Definition::kValue);
InsertBefore(call,
new CheckArrayBoundInstr(new Value(length),
new Value(index),
cid,
call),
call->env(),
Definition::kEffect);
}
return new LoadIndexedInstr(new Value(str),
new Value(index),
FlowGraphCompiler::ElementSizeFor(cid),
cid,
Isolate::kNoDeoptId); // Can't deoptimize.
}
void FlowGraphOptimizer::ReplaceWithMathCFunction(
InstanceCallInstr* call,
MethodRecognizer::Kind recognized_kind) {
AddReceiverCheck(call);
ZoneGrowableArray<Value*>* args =
new ZoneGrowableArray<Value*>(call->ArgumentCount());
for (intptr_t i = 0; i < call->ArgumentCount(); i++) {
args->Add(new Value(call->ArgumentAt(i)));
}
InvokeMathCFunctionInstr* invoke =
new InvokeMathCFunctionInstr(args, call, recognized_kind);
ReplaceCall(call, invoke);
}
static bool IsSupportedByteArrayCid(intptr_t cid) {
switch (cid) {
case kInt8ArrayCid:
case kUint8ArrayCid:
case kUint8ClampedArrayCid:
case kExternalUint8ArrayCid:
case kExternalUint8ClampedArrayCid:
case kInt16ArrayCid:
case kUint16ArrayCid:
case kInt32ArrayCid:
case kUint32ArrayCid:
case kFloat32ArrayCid:
case kFloat64ArrayCid:
return true;
default:
return false;
}
}
// Inline only simple, frequently called core library methods.
bool FlowGraphOptimizer::TryInlineInstanceMethod(InstanceCallInstr* call) {
ASSERT(call->HasICData());
const ICData& ic_data = *call->ic_data();
if ((ic_data.NumberOfChecks() == 0) || !ic_data.HasOneTarget()) {
// No type feedback collected or multiple targets found.
return false;
}
Function& target = Function::Handle();
GrowableArray<intptr_t> class_ids;
ic_data.GetCheckAt(0, &class_ids, &target);
MethodRecognizer::Kind recognized_kind =
MethodRecognizer::RecognizeKind(target);
// Byte array access.
switch (recognized_kind) {
case MethodRecognizer::kFloat32ArrayGetIndexed:
case MethodRecognizer::kFloat64ArrayGetIndexed:
case MethodRecognizer::kInt8ArrayGetIndexed:
case MethodRecognizer::kUint8ArrayGetIndexed:
case MethodRecognizer::kUint8ClampedArrayGetIndexed:
case MethodRecognizer::kExternalUint8ArrayGetIndexed:
case MethodRecognizer::kExternalUint8ClampedArrayGetIndexed:
case MethodRecognizer::kInt16ArrayGetIndexed:
case MethodRecognizer::kUint16ArrayGetIndexed:
case MethodRecognizer::kInt32ArrayGetIndexed:
case MethodRecognizer::kUint32ArrayGetIndexed:
return TryReplaceWithLoadIndexed(call);
case MethodRecognizer::kFloat32ArraySetIndexed:
case MethodRecognizer::kFloat64ArraySetIndexed:
case MethodRecognizer::kInt8ArraySetIndexed:
case MethodRecognizer::kUint8ArraySetIndexed:
case MethodRecognizer::kUint8ClampedArraySetIndexed:
case MethodRecognizer::kExternalUint8ArraySetIndexed:
case MethodRecognizer::kExternalUint8ClampedArraySetIndexed:
case MethodRecognizer::kInt16ArraySetIndexed:
case MethodRecognizer::kUint16ArraySetIndexed:
case MethodRecognizer::kInt32ArraySetIndexed:
case MethodRecognizer::kUint32ArraySetIndexed:
return TryInlineByteArraySetIndexed(call);
default:
break;
}
if ((recognized_kind == MethodRecognizer::kStringBaseCodeUnitAt) &&
(ic_data.NumberOfChecks() == 1) &&
((class_ids[0] == kOneByteStringCid) ||
(class_ids[0] == kTwoByteStringCid))) {
LoadIndexedInstr* instr = BuildStringCodeUnitAt(call, class_ids[0]);
ReplaceCall(call, instr);
return true;
}
if ((recognized_kind == MethodRecognizer::kStringBaseCharAt) &&
(ic_data.NumberOfChecks() == 1) &&
(class_ids[0] == kOneByteStringCid)) {
// TODO(fschneider): Handle TwoByteString.
LoadIndexedInstr* load_char_code =
BuildStringCodeUnitAt(call, class_ids[0]);
InsertBefore(call, load_char_code, NULL, Definition::kValue);
StringFromCharCodeInstr* char_at =
new StringFromCharCodeInstr(new Value(load_char_code),
kOneByteStringCid);
ReplaceCall(call, char_at);
return true;
}
if ((recognized_kind == MethodRecognizer::kIntegerToDouble) &&
(class_ids[0] == kSmiCid)) {
SmiToDoubleInstr* s2d_instr = new SmiToDoubleInstr(call);
call->ReplaceWith(s2d_instr, current_iterator());
// Pushed arguments are not removed because SmiToDouble is implemented
// as a call.
return true;
}
if (class_ids[0] == kDoubleCid) {
switch (recognized_kind) {
case MethodRecognizer::kDoubleToInteger: {
AddReceiverCheck(call);
ASSERT(call->HasICData());
const ICData& ic_data = *call->ic_data();
Definition* input = call->ArgumentAt(0);
Definition* d2i_instr = NULL;
if (ic_data.deopt_reason() == kDeoptDoubleToSmi) {
// Do not repeatedly deoptimize because result didn't fit into Smi.
d2i_instr = new DoubleToIntegerInstr(new Value(input), call);
} else {
// Optimistically assume result fits into Smi.
d2i_instr = new DoubleToSmiInstr(new Value(input), call);
}
ReplaceCall(call, d2i_instr);
return true;
}
case MethodRecognizer::kDoubleMod:
case MethodRecognizer::kDoublePow:
case MethodRecognizer::kDoubleRound:
ReplaceWithMathCFunction(call, recognized_kind);
return true;
case MethodRecognizer::kDoubleTruncate:
case MethodRecognizer::kDoubleFloor:
case MethodRecognizer::kDoubleCeil:
if (!CPUFeatures::double_truncate_round_supported()) {
ReplaceWithMathCFunction(call, recognized_kind);
} else {
AddReceiverCheck(call);
DoubleToDoubleInstr* d2d_instr =
new DoubleToDoubleInstr(new Value(call->ArgumentAt(0)),
call,
recognized_kind);
ReplaceCall(call, d2d_instr);
}
return true;
default:
// Unsupported method.
return false;
}
}
if (IsSupportedByteArrayCid(class_ids[0]) &&
(ic_data.NumberOfChecks() == 1)) {
Definition* array_op = NULL;
switch (recognized_kind) {
case MethodRecognizer::kByteArrayBaseGetInt8:
array_op = BuildByteArrayViewLoad(call, class_ids[0], kInt8ArrayCid);
break;
case MethodRecognizer::kByteArrayBaseGetUint8:
array_op = BuildByteArrayViewLoad(call, class_ids[0], kUint8ArrayCid);
break;
case MethodRecognizer::kByteArrayBaseGetInt16:
array_op = BuildByteArrayViewLoad(call, class_ids[0], kInt16ArrayCid);
break;
case MethodRecognizer::kByteArrayBaseGetUint16:
array_op = BuildByteArrayViewLoad(call, class_ids[0], kUint16ArrayCid);
break;
case MethodRecognizer::kByteArrayBaseGetInt32:
// Check if elements fit into a smi or the platform supports unboxed
// mints.
if ((kSmiBits < 32) && !FlowGraphCompiler::SupportsUnboxedMints()) {
return false;
}
array_op = BuildByteArrayViewLoad(call, class_ids[0], kInt32ArrayCid);
break;
case MethodRecognizer::kByteArrayBaseGetUint32:
// Check if elements fit into a smi or the platform supports unboxed
// mints.
if ((kSmiBits < 32) && !FlowGraphCompiler::SupportsUnboxedMints()) {
return false;
}
array_op = BuildByteArrayViewLoad(call, class_ids[0], kUint32ArrayCid);
break;
case MethodRecognizer::kByteArrayBaseGetFloat32:
array_op = BuildByteArrayViewLoad(call, class_ids[0], kFloat32ArrayCid);
break;
case MethodRecognizer::kByteArrayBaseGetFloat64:
array_op = BuildByteArrayViewLoad(call, class_ids[0], kFloat64ArrayCid);
break;
default:
// Unsupported method.
return false;
}
ASSERT(array_op != NULL);
ReplaceCall(call, array_op);
return true;
}
return false;
}
LoadIndexedInstr* FlowGraphOptimizer::BuildByteArrayViewLoad(
InstanceCallInstr* call,
intptr_t receiver_cid,
intptr_t view_cid) {
Definition* array = call->ArgumentAt(0);
Definition* byte_index = call->ArgumentAt(1);
AddReceiverCheck(call);
const bool is_immutable = true;
LoadFieldInstr* length = new LoadFieldInstr(
new Value(array),
CheckArrayBoundInstr::LengthOffsetFor(receiver_cid),
Type::ZoneHandle(Type::SmiType()),
is_immutable);
length->set_result_cid(kSmiCid);
length->set_recognized_kind(
LoadFieldInstr::RecognizedKindFromArrayCid(receiver_cid));
InsertBefore(call, length, NULL, Definition::kValue);
// len_in_bytes = length * kBytesPerElement(receiver)
intptr_t element_size = FlowGraphCompiler::ElementSizeFor(receiver_cid);
ConstantInstr* bytes_per_element =
new ConstantInstr(Smi::Handle(Smi::New(element_size)));
InsertBefore(call, bytes_per_element, NULL, Definition::kValue);
BinarySmiOpInstr* len_in_bytes =
new BinarySmiOpInstr(Token::kMUL,
call,
new Value(length),
new Value(bytes_per_element));
InsertBefore(call, len_in_bytes, call->env(), Definition::kValue);
// Check byte_index < len_in_bytes.
InsertBefore(call,
new CheckArrayBoundInstr(new Value(len_in_bytes),
new Value(byte_index),
receiver_cid,
call),
call->env(),
Definition::kEffect);
// TODO(fschneider): Optimistically build smi load for Int32 and Uint32
// loads on ia32 like we do for normal array loads, and only revert to
// mint case after deoptimizing here.
return new LoadIndexedInstr(new Value(array),
new Value(byte_index),
1, // Index scale.
view_cid,
Isolate::kNoDeoptId); // Can't deoptimize.
}
// Returns a Boolean constant if all classes in ic_data yield the same type-test
// result and the type tests do not depend on type arguments. Otherwise return
// Bool::null().
RawBool* FlowGraphOptimizer::InstanceOfAsBool(const ICData& ic_data,
const AbstractType& type) const {
ASSERT(ic_data.num_args_tested() == 1); // Unary checks only.
if (!type.IsInstantiated() || type.IsMalformed()) return Bool::null();
const Class& type_class = Class::Handle(type.type_class());
if (type_class.HasTypeArguments()) return Bool::null();
const ClassTable& class_table = *Isolate::Current()->class_table();
Bool& prev = Bool::Handle();
Class& cls = Class::Handle();
for (int i = 0; i < ic_data.NumberOfChecks(); i++) {
cls = class_table.At(ic_data.GetReceiverClassIdAt(i));
if (cls.HasTypeArguments()) return Bool::null();
const bool is_subtype = cls.IsSubtypeOf(TypeArguments::Handle(),
type_class,
TypeArguments::Handle(),
NULL);
if (prev.IsNull()) {
prev = is_subtype ? Bool::True().raw() : Bool::False().raw();
} else {
if (is_subtype != prev.value()) return Bool::null();
}
}
return prev.raw();
}
// TODO(srdjan): Use ICData to check if always true or false.
void FlowGraphOptimizer::ReplaceWithInstanceOf(InstanceCallInstr* call) {
ASSERT(Token::IsTypeTestOperator(call->token_kind()));
Definition* left = call->ArgumentAt(0);
Definition* instantiator = call->ArgumentAt(1);
Definition* type_args = call->ArgumentAt(2);
const AbstractType& type =
AbstractType::Cast(call->ArgumentAt(3)->AsConstant()->value());
const bool negate =
Bool::Cast(call->ArgumentAt(4)->AsConstant()->value()).value();
const ICData& unary_checks =
ICData::ZoneHandle(call->ic_data()->AsUnaryClassChecks());
if (unary_checks.NumberOfChecks() <= FLAG_max_polymorphic_checks) {
Bool& as_bool = Bool::ZoneHandle(InstanceOfAsBool(unary_checks, type));
if (!as_bool.IsNull()) {
AddReceiverCheck(call);
if (negate) {
as_bool = Bool::Get(!as_bool.value());
}
ConstantInstr* bool_const = new ConstantInstr(as_bool);
ReplaceCall(call, bool_const);
return;
}
}
InstanceOfInstr* instance_of =
new InstanceOfInstr(call->token_pos(),
new Value(left),
new Value(instantiator),
new Value(type_args),
type,
negate);
ReplaceCall(call, instance_of);
}
// Tries to optimize instance call by replacing it with a faster instruction
// (e.g, binary op, field load, ..).
void FlowGraphOptimizer::VisitInstanceCall(InstanceCallInstr* instr) {
if (!instr->HasICData() || (instr->ic_data()->NumberOfChecks() == 0)) {
return;
}
const Token::Kind op_kind = instr->token_kind();
// Type test is special as it always gets converted into inlined code.
if (Token::IsTypeTestOperator(op_kind)) {
ReplaceWithInstanceOf(instr);
return;
}
const ICData& unary_checks =
ICData::ZoneHandle(instr->ic_data()->AsUnaryClassChecks());
if ((unary_checks.NumberOfChecks() > FLAG_max_polymorphic_checks) &&
InstanceCallNeedsClassCheck(instr)) {
// Too many checks, it will be megamorphic which needs unary checks.
instr->set_ic_data(&unary_checks);
return;
}
if ((op_kind == Token::kASSIGN_INDEX) &&
TryReplaceWithStoreIndexed(instr)) {
return;
}
if ((op_kind == Token::kINDEX) && TryReplaceWithLoadIndexed(instr)) {
return;
}
if (Token::IsBinaryOperator(op_kind) &&
TryReplaceWithBinaryOp(instr, op_kind)) {
return;
}
if (Token::IsPrefixOperator(op_kind) &&
TryReplaceWithUnaryOp(instr, op_kind)) {
return;
}
if ((op_kind == Token::kGET) && TryInlineInstanceGetter(instr)) {
return;
}
if ((op_kind == Token::kSET) &&
TryInlineInstanceSetter(instr, unary_checks)) {
return;
}
if (TryInlineInstanceMethod(instr)) {
return;
}
const bool has_one_target = unary_checks.HasOneTarget();
if (has_one_target) {
const bool is_method_extraction =
Function::Handle(unary_checks.GetTargetAt(0)).IsMethodExtractor();
if ((is_method_extraction && !MethodExtractorNeedsClassCheck(instr)) ||
(!is_method_extraction && !InstanceCallNeedsClassCheck(instr))) {
const bool call_with_checks = false;
PolymorphicInstanceCallInstr* call =
new PolymorphicInstanceCallInstr(instr, unary_checks,
call_with_checks);
instr->ReplaceWith(call, current_iterator());
return;
}
}
if (unary_checks.NumberOfChecks() <= FLAG_max_polymorphic_checks) {
bool call_with_checks;
if (has_one_target) {
// Type propagation has not run yet, we cannot eliminate the check.
AddReceiverCheck(instr);
// Call can still deoptimize, do not detach environment from instr.
call_with_checks = false;
} else {
call_with_checks = true;
}
PolymorphicInstanceCallInstr* call =
new PolymorphicInstanceCallInstr(instr, unary_checks,
call_with_checks);
instr->ReplaceWith(call, current_iterator());
}
}
void FlowGraphOptimizer::VisitStaticCall(StaticCallInstr* call) {
MethodRecognizer::Kind recognized_kind =
MethodRecognizer::RecognizeKind(call->function());
if (recognized_kind == MethodRecognizer::kMathSqrt) {
MathSqrtInstr* sqrt =
new MathSqrtInstr(new Value(call->ArgumentAt(0)), call);
ReplaceCall(call, sqrt);
}
}
bool FlowGraphOptimizer::TryInlineInstanceSetter(InstanceCallInstr* instr,
const ICData& unary_ic_data) {
ASSERT((unary_ic_data.NumberOfChecks() > 0) &&
(unary_ic_data.num_args_tested() == 1));
if (FLAG_enable_type_checks) {
// TODO(srdjan): Add assignable check node if --enable_type_checks.
return false;
}
ASSERT(instr->HasICData());
if (unary_ic_data.NumberOfChecks() == 0) {
// No type feedback collected.
return false;
}
if (!unary_ic_data.HasOneTarget()) {
// TODO(srdjan): Implement when not all targets are the same.
return false;
}
Function& target = Function::Handle();
intptr_t class_id;
unary_ic_data.GetOneClassCheckAt(0, &class_id, &target);
if (target.kind() != RawFunction::kImplicitSetter) {
// Not an implicit setter.
// TODO(srdjan): Inline special setters.
return false;
}
// Inline implicit instance setter.
const String& field_name =
String::Handle(Field::NameFromSetter(instr->function_name()));
const Field& field = Field::Handle(GetField(class_id, field_name));
ASSERT(!field.IsNull());
if (InstanceCallNeedsClassCheck(instr)) {
AddReceiverCheck(instr);
}
StoreBarrierType needs_store_barrier = kEmitStoreBarrier;
if (ArgIsAlwaysSmi(*instr->ic_data(), 1)) {
InsertBefore(instr,
new CheckSmiInstr(new Value(instr->ArgumentAt(1)),
instr->deopt_id()),
instr->env(),
Definition::kEffect);
needs_store_barrier = kNoStoreBarrier;
}
StoreInstanceFieldInstr* store = new StoreInstanceFieldInstr(
field,
new Value(instr->ArgumentAt(0)),
new Value(instr->ArgumentAt(1)),
needs_store_barrier);
// Discard the environment from the original instruction because the store
// can't deoptimize.
instr->RemoveEnvironment();
ReplaceCall(instr, store);
return true;
}
void FlowGraphOptimizer::HandleRelationalOp(RelationalOpInstr* comp) {
if (!comp->HasICData() || (comp->ic_data()->NumberOfChecks() == 0)) {
return;
}
const ICData& ic_data = *comp->ic_data();
Instruction* instr = current_iterator()->Current();
if (ic_data.NumberOfChecks() == 1) {
ASSERT(ic_data.HasOneTarget());
if (HasOnlyTwoSmis(ic_data)) {
InsertBefore(instr,
new CheckSmiInstr(comp->left()->Copy(), comp->deopt_id()),
instr->env(),
Definition::kEffect);
InsertBefore(instr,
new CheckSmiInstr(comp->right()->Copy(), comp->deopt_id()),
instr->env(),
Definition::kEffect);
comp->set_operands_class_id(kSmiCid);
} else if (ShouldSpecializeForDouble(ic_data)) {
comp->set_operands_class_id(kDoubleCid);
} else if (HasTwoMintOrSmi(*comp->ic_data()) &&
FlowGraphCompiler::SupportsUnboxedMints()) {
comp->set_operands_class_id(kMintCid);
} else {
ASSERT(comp->operands_class_id() == kIllegalCid);
}
} else if (HasTwoMintOrSmi(*comp->ic_data()) &&
FlowGraphCompiler::SupportsUnboxedMints()) {
comp->set_operands_class_id(kMintCid);
}
}
void FlowGraphOptimizer::VisitRelationalOp(RelationalOpInstr* instr) {
HandleRelationalOp(instr);
}
template <typename T>
void FlowGraphOptimizer::HandleEqualityCompare(EqualityCompareInstr* comp,
T current_instruction) {
// If one of the inputs is null, no ICdata will be collected.
if (comp->left()->BindsToConstantNull() ||
comp->right()->BindsToConstantNull()) {
Token::Kind strict_kind = (comp->kind() == Token::kEQ) ?
Token::kEQ_STRICT : Token::kNE_STRICT;
StrictCompareInstr* strict_comp =
new StrictCompareInstr(strict_kind,
comp->left()->Copy(),
comp->right()->Copy());
current_instruction->ReplaceWith(strict_comp, current_iterator());
return;
}
if (!comp->HasICData() || (comp->ic_data()->NumberOfChecks() == 0)) {
return;
}
ASSERT(comp->ic_data()->num_args_tested() == 2);
if (comp->ic_data()->NumberOfChecks() == 1) {
GrowableArray<intptr_t> class_ids;
Function& target = Function::Handle();
comp->ic_data()->GetCheckAt(0, &class_ids, &target);
// TODO(srdjan): allow for mixed mode int/double comparison.
if ((class_ids[0] == kSmiCid) && (class_ids[1] == kSmiCid)) {
InsertBefore(current_instruction,
new CheckSmiInstr(comp->left()->Copy(), comp->deopt_id()),
current_instruction->env(),
Definition::kEffect);
InsertBefore(current_instruction,
new CheckSmiInstr(comp->right()->Copy(), comp->deopt_id()),
current_instruction->env(),
Definition::kEffect);
comp->set_receiver_class_id(kSmiCid);
} else if ((class_ids[0] == kDoubleCid) && (class_ids[1] == kDoubleCid)) {
comp->set_receiver_class_id(kDoubleCid);
} else if (HasTwoMintOrSmi(*comp->ic_data()) &&
FlowGraphCompiler::SupportsUnboxedMints()) {
comp->set_receiver_class_id(kMintCid);
} else {
ASSERT(comp->receiver_class_id() == kIllegalCid);
}
} else if (HasTwoMintOrSmi(*comp->ic_data()) &&
FlowGraphCompiler::SupportsUnboxedMints()) {
comp->set_receiver_class_id(kMintCid);
}
if (comp->receiver_class_id() != kIllegalCid) {
// Done.
return;
}
// Check if ICDData contains checks with Smi/Null combinations. In that case
// we can still emit the optimized Smi equality operation but need to add
// checks for null or Smi.
// TODO(srdjan): Add it for Double and Mint.
GrowableArray<intptr_t> smi_or_null(2);
smi_or_null.Add(kSmiCid);
smi_or_null.Add(kNullCid);
if (ICDataHasOnlyReceiverArgumentClassIds(*comp->ic_data(),
smi_or_null,
smi_or_null)) {
const ICData& unary_checks_0 =
ICData::ZoneHandle(comp->ic_data()->AsUnaryClassChecks());
AddCheckClass(comp->left()->definition(),
unary_checks_0,
comp->deopt_id(),
current_instruction->env(),
current_instruction);
const ICData& unary_checks_1 =
ICData::ZoneHandle(comp->ic_data()->AsUnaryClassChecksForArgNr(1));
AddCheckClass(comp->right()->definition(),
unary_checks_1,
comp->deopt_id(),
current_instruction->env(),
current_instruction);
comp->set_receiver_class_id(kSmiCid);
}
}
void FlowGraphOptimizer::VisitEqualityCompare(EqualityCompareInstr* instr) {
HandleEqualityCompare(instr, instr);
}
void FlowGraphOptimizer::VisitBranch(BranchInstr* instr) {
ComparisonInstr* comparison = instr->comparison();
if (comparison->IsRelationalOp()) {
HandleRelationalOp(comparison->AsRelationalOp());
} else if (comparison->IsEqualityCompare()) {
HandleEqualityCompare(comparison->AsEqualityCompare(), instr);
} else {
ASSERT(comparison->IsStrictCompare());
// Nothing to do.
}
}
static bool MayBeBoxableNumber(intptr_t cid) {
return (cid == kDynamicCid) ||
(cid == kMintCid) ||
(cid == kBigintCid) ||
(cid == kDoubleCid);
}
// Check if number check is not needed.
void FlowGraphOptimizer::VisitStrictCompare(StrictCompareInstr* instr) {
if (!instr->needs_number_check()) return;
// If one of the input is not a boxable number (Mint, Double, Bigint), no
// need for number checks.
if (!MayBeBoxableNumber(instr->left()->Type()->ToCid()) ||
!MayBeBoxableNumber(instr->right()->Type()->ToCid())) {
instr->set_needs_number_check(false);
}
}
// Range analysis for smi values.
class RangeAnalysis : public ValueObject {
public:
explicit RangeAnalysis(FlowGraph* flow_graph)
: flow_graph_(flow_graph),
marked_defns_(NULL) { }
// Infer ranges for all values and remove overflow checks from binary smi
// operations when proven redundant.
void Analyze();
private:
// Collect all values that were proven to be smi in smi_values_ array and all
// CheckSmi instructions in smi_check_ array.
void CollectSmiValues();
// Iterate over smi values and constrain them at branch successors.
// Additionally constraint values after CheckSmi instructions.
void InsertConstraints();
// Iterate over uses of the given definition and discover branches that
// constrain it. Insert appropriate Constraint instructions at true
// and false successor and rename all dominated uses to refer to a
// Constraint instead of this definition.
void InsertConstraintsFor(Definition* defn);
// Create a constraint for defn, insert it after given instruction and
// rename all uses that are dominated by it.
ConstraintInstr* InsertConstraintFor(Definition* defn,
Range* constraint,
Instruction* after);
void ConstrainValueAfterBranch(Definition* defn, Value* use);
void ConstrainValueAfterCheckArrayBound(Definition* defn,
CheckArrayBoundInstr* check);
// Replace uses of the definition def that are dominated by instruction dom
// with uses of other definition.
void RenameDominatedUses(Definition* def,
Instruction* dom,
Definition* other);
// Walk the dominator tree and infer ranges for smi values.
void InferRanges();
void InferRangesRecursive(BlockEntryInstr* block);
enum Direction {
kUnknown,
kPositive,
kNegative,
kBoth
};
Range* InferInductionVariableRange(JoinEntryInstr* loop_header,
PhiInstr* var);
void ResetWorklist();
void MarkDefinition(Definition* defn);
static Direction ToDirection(Value* val);
static Direction Invert(Direction direction) {
return (direction == kPositive) ? kNegative : kPositive;
}
static void UpdateDirection(Direction* direction,
Direction new_direction) {
if (*direction != new_direction) {
if (*direction != kUnknown) new_direction = kBoth;
*direction = new_direction;
}
}
// Remove artificial Constraint instructions and replace them with actual
// unconstrained definitions.
void RemoveConstraints();
FlowGraph* flow_graph_;
GrowableArray<Definition*> smi_values_; // Value that are known to be smi.
GrowableArray<CheckSmiInstr*> smi_checks_; // All CheckSmi instructions.
// All Constraints inserted during InsertConstraints phase. They are treated
// as smi values.
GrowableArray<ConstraintInstr*> constraints_;
// Bitvector for a quick filtering of known smi values.
BitVector* smi_definitions_;
// Worklist for induction variables analysis.
GrowableArray<Definition*> worklist_;
BitVector* marked_defns_;
DISALLOW_COPY_AND_ASSIGN(RangeAnalysis);
};
void RangeAnalysis::Analyze() {
CollectSmiValues();
InsertConstraints();
InferRanges();
RemoveConstraints();
}
void RangeAnalysis::CollectSmiValues() {
for (BlockIterator block_it = flow_graph_->reverse_postorder_iterator();
!block_it.Done();
block_it.Advance()) {
BlockEntryInstr* block = block_it.Current();
for (ForwardInstructionIterator instr_it(block);
!instr_it.Done();
instr_it.Advance()) {
Instruction* current = instr_it.Current();
Definition* defn = current->AsDefinition();
if (defn != NULL) {
if ((defn->Type()->ToCid() == kSmiCid) &&
(defn->ssa_temp_index() != -1)) {
smi_values_.Add(defn);
}
} else if (current->IsCheckSmi()) {
smi_checks_.Add(current->AsCheckSmi());
}
}
JoinEntryInstr* join = block->AsJoinEntry();
if (join != NULL) {
for (PhiIterator phi_it(join); !phi_it.Done(); phi_it.Advance()) {
PhiInstr* current = phi_it.Current();
if ((current->Type()->ToCid() == kSmiCid)) {
smi_values_.Add(current);
}
}
}
}
}
// Returns true if use is dominated by the given instruction.
// Note: uses that occur at instruction itself are not dominated by it.
static bool IsDominatedUse(Instruction* dom, Value* use) {
BlockEntryInstr* dom_block = dom->GetBlock();
Instruction* instr = use->instruction();
PhiInstr* phi = instr->AsPhi();
if (phi != NULL) {
return dom_block->Dominates(phi->block()->PredecessorAt(use->use_index()));
}
BlockEntryInstr* use_block = instr->GetBlock();
if (use_block == dom_block) {
// Fast path for the case of block entry.
if (dom_block == dom) return true;
for (Instruction* curr = dom->next(); curr != NULL; curr = curr->next()) {
if (curr == instr) return true;
}
return false;
}
return dom_block->Dominates(use_block);
}
void RangeAnalysis::RenameDominatedUses(Definition* def,
Instruction* dom,
Definition* other) {
for (Value::Iterator it(def->input_use_list());
!it.Done();
it.Advance()) {
Value* use = it.Current();
// Skip dead phis.
PhiInstr* phi = use->instruction()->AsPhi();
ASSERT((phi == NULL) || phi->is_alive());
if (IsDominatedUse(dom, use)) {
use->BindTo(other);
}
}
}
// For a comparison operation return an operation for the equivalent flipped
// comparison: a (op) b === b (op') a.
static Token::Kind FlipComparison(Token::Kind op) {
switch (op) {
case Token::kEQ: return Token::kEQ;
case Token::kNE: return Token::kNE;
case Token::kLT: return Token::kGT;
case Token::kGT: return Token::kLT;
case Token::kLTE: return Token::kGTE;
case Token::kGTE: return Token::kLTE;
default:
UNREACHABLE();
return Token::kILLEGAL;
}
}
// For a comparison operation return an operation for the negated comparison:
// !(a (op) b) === a (op') b
static Token::Kind NegateComparison(Token::Kind op) {
switch (op) {
case Token::kEQ: return Token::kNE;
case Token::kNE: return Token::kEQ;
case Token::kLT: return Token::kGTE;
case Token::kGT: return Token::kLTE;
case Token::kLTE: return Token::kGT;
case Token::kGTE: return Token::kLT;
default:
UNREACHABLE();
return Token::kILLEGAL;
}
}
// Given a boundary (right operand) and a comparison operation return
// a symbolic range constraint for the left operand of the comparison assuming
// that it evaluated to true.
// For example for the comparison a < b symbol a is constrained with range
// [Smi::kMinValue, b - 1].
static Range* ConstraintRange(Token::Kind op, Definition* boundary) {
switch (op) {
case Token::kEQ:
return new Range(RangeBoundary::FromDefinition(boundary),
RangeBoundary::FromDefinition(boundary));
case Token::kNE:
return Range::Unknown();
case Token::kLT:
return new Range(RangeBoundary::MinSmi(),
RangeBoundary::FromDefinition(boundary, -1));
case Token::kGT:
return new Range(RangeBoundary::FromDefinition(boundary, 1),
RangeBoundary::MaxSmi());
case Token::kLTE:
return new Range(RangeBoundary::MinSmi(),
RangeBoundary::FromDefinition(boundary));
case Token::kGTE:
return new Range(RangeBoundary::FromDefinition(boundary),
RangeBoundary::MaxSmi());
default:
UNREACHABLE();
return Range::Unknown();
}
}
ConstraintInstr* RangeAnalysis::InsertConstraintFor(Definition* defn,
Range* constraint_range,
Instruction* after) {
// No need to constrain constants.
if (defn->IsConstant()) return NULL;
ConstraintInstr* constraint =
new ConstraintInstr(new Value(defn), constraint_range);
flow_graph_->InsertAfter(after, constraint, NULL, Definition::kValue);
RenameDominatedUses(defn, constraint, constraint);
constraints_.Add(constraint);
return constraint;
}
void RangeAnalysis::ConstrainValueAfterBranch(Definition* defn, Value* use) {
BranchInstr* branch = use->instruction()->AsBranch();
RelationalOpInstr* rel_op = branch->comparison()->AsRelationalOp();
if ((rel_op != NULL) && (rel_op->operands_class_id() == kSmiCid)) {
// Found comparison of two smis. Constrain defn at true and false
// successors using the other operand as a boundary.
Definition* boundary;
Token::Kind op_kind;
if (use->use_index() == 0) { // Left operand.
boundary = rel_op->InputAt(1)->definition();
op_kind = rel_op->kind();
} else {
ASSERT(use->use_index() == 1); // Right operand.
boundary = rel_op->InputAt(0)->definition();
// InsertConstraintFor assumes that defn is left operand of a
// comparison if it is right operand flip the comparison.
op_kind = FlipComparison(rel_op->kind());
}
// Constrain definition at the true successor.
ConstraintInstr* true_constraint =
InsertConstraintFor(defn,
ConstraintRange(op_kind, boundary),
branch->true_successor());
// Mark true_constraint an artificial use of boundary. This ensures
// that constraint's range is recalculated if boundary's range changes.
if (true_constraint != NULL) true_constraint->AddDependency(boundary);
// Constrain definition with a negated condition at the false successor.
ConstraintInstr* false_constraint =
InsertConstraintFor(
defn,
ConstraintRange(NegateComparison(op_kind), boundary),
branch->false_successor());
// Mark false_constraint an artificial use of boundary. This ensures
// that constraint's range is recalculated if boundary's range changes.
if (false_constraint != NULL) false_constraint->AddDependency(boundary);
}
}
void RangeAnalysis::InsertConstraintsFor(Definition* defn) {
for (Value* use = defn->input_use_list();
use != NULL;
use = use->next_use()) {
if (use->instruction()->IsBranch()) {
ConstrainValueAfterBranch(defn, use);
} else if (use->instruction()->IsCheckArrayBound()) {
ConstrainValueAfterCheckArrayBound(
defn,
use->instruction()->AsCheckArrayBound());
}
}
}
void RangeAnalysis::ConstrainValueAfterCheckArrayBound(
Definition* defn, CheckArrayBoundInstr* check) {
if (!CheckArrayBoundInstr::IsFixedLengthArrayType(check->array_type())) {
return;
}
Definition* length = check->length()->definition();
Range* constraint_range = new Range(
RangeBoundary::FromConstant(0),
RangeBoundary::FromDefinition(length, -1));
InsertConstraintFor(defn, constraint_range, check);
}
void RangeAnalysis::InsertConstraints() {
for (intptr_t i = 0; i < smi_checks_.length(); i++) {
CheckSmiInstr* check = smi_checks_[i];
ConstraintInstr* constraint =
InsertConstraintFor(check->value()->definition(),
Range::Unknown(),
check);
if (constraint != NULL) {
InsertConstraintsFor(constraint); // Constrain uses further.
}
}
for (intptr_t i = 0; i < smi_values_.length(); i++) {
InsertConstraintsFor(smi_values_[i]);
}
}
void RangeAnalysis::ResetWorklist() {
if (marked_defns_ == NULL) {
marked_defns_ = new BitVector(flow_graph_->current_ssa_temp_index());
} else {
marked_defns_->Clear();
}
worklist_.Clear();
}
void RangeAnalysis::MarkDefinition(Definition* defn) {
// Unwrap constrained value.
while (defn->IsConstraint()) {
defn = defn->AsConstraint()->value()->definition();
}
if (!marked_defns_->Contains(defn->ssa_temp_index())) {
worklist_.Add(defn);
marked_defns_->Add(defn->ssa_temp_index());
}
}
RangeAnalysis::Direction RangeAnalysis::ToDirection(Value* val) {
if (val->BindsToConstant()) {
return (Smi::Cast(val->BoundConstant()).Value() >= 0) ? kPositive
: kNegative;
} else if (val->definition()->range() != NULL) {
Range* range = val->definition()->range();
if (Range::ConstantMin(range).value() >= 0) {
return kPositive;
} else if (Range::ConstantMax(range).value() <= 0) {
return kNegative;
}
}
return kUnknown;
}
Range* RangeAnalysis::InferInductionVariableRange(JoinEntryInstr* loop_header,
PhiInstr* var) {
BitVector* loop_info = loop_header->loop_info();
Definition* initial_value = NULL;
Direction direction = kUnknown;
ResetWorklist();
MarkDefinition(var);
while (!worklist_.is_empty()) {
Definition* defn = worklist_.RemoveLast();
if (defn->IsPhi()) {
PhiInstr* phi = defn->AsPhi();
for (intptr_t i = 0; i < phi->InputCount(); i++) {
Definition* defn = phi->InputAt(i)->definition();
if (!loop_info->Contains(defn->GetBlock()->preorder_number())) {
// The value is coming from outside of the loop.
if (initial_value == NULL) {
initial_value = defn;
continue;
} else if (initial_value == defn) {
continue;
} else {
return NULL;
}
}
MarkDefinition(defn);
}
} else if (defn->IsBinarySmiOp()) {
BinarySmiOpInstr* binary_op = defn->AsBinarySmiOp();
switch (binary_op->op_kind()) {
case Token::kADD: {
const Direction growth_right =
ToDirection(binary_op->right());
if (growth_right != kUnknown) {
UpdateDirection(&direction, growth_right);
MarkDefinition(binary_op->left()->definition());
break;
}
const Direction growth_left =
ToDirection(binary_op->left());
if (growth_left != kUnknown) {
UpdateDirection(&direction, growth_left);
MarkDefinition(binary_op->right()->definition());
break;
}
return NULL;
}
case Token::kSUB: {
const Direction growth_right =
ToDirection(binary_op->right());
if (growth_right != kUnknown) {
UpdateDirection(&direction, Invert(growth_right));
MarkDefinition(binary_op->left()->definition());
break;
}
return NULL;
}
default:
return NULL;
}
} else {
return NULL;
}
}
// We transitively discovered all dependencies of the given phi
// and confirmed that it depends on a single value coming from outside of
// the loop and some linear combinations of itself.
// Compute the range based on initial value and the direction of the growth.
switch (direction) {
case kPositive:
return new Range(RangeBoundary::FromDefinition(initial_value),
RangeBoundary::MaxSmi());
case kNegative:
return new Range(RangeBoundary::MinSmi(),
RangeBoundary::FromDefinition(initial_value));
case kUnknown:
case kBoth:
return Range::Unknown();
}
UNREACHABLE();
return NULL;
}
void RangeAnalysis::InferRangesRecursive(BlockEntryInstr* block) {
JoinEntryInstr* join = block->AsJoinEntry();
if (join != NULL) {
const bool is_loop_header = (join->loop_info() != NULL);
for (PhiIterator it(join); !it.Done(); it.Advance()) {
PhiInstr* phi = it.Current();
if (smi_definitions_->Contains(phi->ssa_temp_index())) {
if (is_loop_header) {
// Try recognizing simple induction variables.
Range* range = InferInductionVariableRange(join, phi);
if (range != NULL) {
phi->range_ = range;
continue;
}
}
phi->InferRange();
}
}
}
for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
Instruction* current = it.Current();
Definition* defn = current->AsDefinition();
if ((defn != NULL) &&
(defn->ssa_temp_index() != -1) &&
smi_definitions_->Contains(defn->ssa_temp_index())) {
defn->InferRange();
} else if (FLAG_array_bounds_check_elimination &&
current->IsCheckArrayBound()) {
CheckArrayBoundInstr* check = current->AsCheckArrayBound();
RangeBoundary array_length =
RangeBoundary::FromDefinition(check->length()->definition());
if (check->IsRedundant(array_length)) {
it.RemoveCurrentFromGraph();
}
}
}
for (intptr_t i = 0; i < block->dominated_blocks().length(); ++i) {
InferRangesRecursive(block->dominated_blocks()[i]);
}
}
void RangeAnalysis::InferRanges() {
// Initialize bitvector for quick filtering of smi values.
smi_definitions_ = new BitVector(flow_graph_->current_ssa_temp_index());
for (intptr_t i = 0; i < smi_values_.length(); i++) {
smi_definitions_->Add(smi_values_[i]->ssa_temp_index());
}
for (intptr_t i = 0; i < constraints_.length(); i++) {
smi_definitions_->Add(constraints_[i]->ssa_temp_index());
}
// Infer initial values of ranges.
InferRangesRecursive(flow_graph_->graph_entry());
if (FLAG_trace_range_analysis) {
OS::Print("---- after range analysis -------\n");
FlowGraphPrinter printer(*flow_graph_);
printer.PrintBlocks();
}
}
void RangeAnalysis::RemoveConstraints() {
for (intptr_t i = 0; i < constraints_.length(); i++) {
Definition* def = constraints_[i]->value()->definition();
// Some constraints might be constraining constraints. Unwind the chain of
// constraints until we reach the actual definition.
while (def->IsConstraint()) {
def = def->AsConstraint()->value()->definition();
}
constraints_[i]->ReplaceUsesWith(def);
constraints_[i]->RemoveFromGraph();
}
}
void FlowGraphOptimizer::InferSmiRanges() {
RangeAnalysis range_analysis(flow_graph_);
range_analysis.Analyze();
}
static BlockEntryInstr* FindPreHeader(BlockEntryInstr* header) {
for (intptr_t j = 0; j < header->PredecessorCount(); ++j) {
BlockEntryInstr* candidate = header->PredecessorAt(j);
if (header->dominator() == candidate) {
return candidate;
}
}
return NULL;
}
LICM::LICM(FlowGraph* flow_graph) : flow_graph_(flow_graph) {
}
void LICM::Hoist(ForwardInstructionIterator* it,
BlockEntryInstr* pre_header,
Instruction* current) {
// TODO(fschneider): Avoid repeated deoptimization when
// speculatively hoisting checks.
if (FLAG_trace_optimization) {
OS::Print("Hoisting instruction %s:%"Pd" from B%"Pd" to B%"Pd"\n",
current->DebugName(),
current->GetDeoptId(),
current->GetBlock()->block_id(),
pre_header->block_id());
}
// Move the instruction out of the loop.
current->RemoveEnvironment();
it->RemoveCurrentFromGraph();
GotoInstr* last = pre_header->last_instruction()->AsGoto();
// Using kind kEffect will not assign a fresh ssa temporary index.
flow_graph()->InsertBefore(last, current, last->env(), Definition::kEffect);
current->deopt_id_ = last->GetDeoptId();
}
void LICM::TryHoistCheckSmiThroughPhi(ForwardInstructionIterator* it,
BlockEntryInstr* header,
BlockEntryInstr* pre_header,
CheckSmiInstr* current) {
PhiInstr* phi = current->value()->definition()->AsPhi();
if (!header->loop_info()->Contains(phi->block()->preorder_number())) {
return;
}
if (phi->Type()->ToCid() == kSmiCid) {
it->RemoveCurrentFromGraph();
return;
}
// Check if there is only a single kDynamicCid input to the phi that
// comes from the pre-header.
const intptr_t kNotFound = -1;
intptr_t non_smi_input = kNotFound;
for (intptr_t i = 0; i < phi->InputCount(); ++i) {
Value* input = phi->InputAt(i);
if (input->Type()->ToCid() != kSmiCid) {
if ((non_smi_input != kNotFound) ||
(input->Type()->ToCid() != kDynamicCid)) {
// There are multiple kDynamicCid inputs or there is an input that is
// known to be non-smi.
return;
} else {
non_smi_input = i;
}
}
}
if ((non_smi_input == kNotFound) ||
(phi->block()->PredecessorAt(non_smi_input) != pre_header)) {
return;
}
// Host CheckSmi instruction and make this phi smi one.
Hoist(it, pre_header, current);
// Replace value we are checking with phi's input.
current->value()->BindTo(phi->InputAt(non_smi_input)->definition());
phi->UpdateType(CompileType::FromCid(kSmiCid));
}
void LICM::Optimize() {
GrowableArray<BlockEntryInstr*> loop_headers;
flow_graph()->ComputeLoops(&loop_headers);
for (intptr_t i = 0; i < loop_headers.length(); ++i) {
BlockEntryInstr* header = loop_headers[i];
// Skip loop that don't have a pre-header block.
BlockEntryInstr* pre_header = FindPreHeader(header);
if (pre_header == NULL) continue;
for (BitVector::Iterator loop_it(header->loop_info());
!loop_it.Done();
loop_it.Advance()) {
BlockEntryInstr* block = flow_graph()->preorder()[loop_it.Current()];
for (ForwardInstructionIterator it(block);
!it.Done();
it.Advance()) {
Instruction* current = it.Current();
if (!current->IsPushArgument() && !current->AffectedBySideEffect()) {
bool inputs_loop_invariant = true;
for (int i = 0; i < current->InputCount(); ++i) {
Definition* input_def = current->InputAt(i)->definition();
if (!input_def->GetBlock()->Dominates(pre_header)) {
inputs_loop_invariant = false;
break;
}
}
if (inputs_loop_invariant &&
!current->IsAssertAssignable() &&
!current->IsAssertBoolean()) {
// TODO(fschneider): Enable hoisting of Assert-instructions
// if it safe to do.
Hoist(&it, pre_header, current);
} else if (current->IsCheckSmi() &&
current->InputAt(0)->definition()->IsPhi()) {
TryHoistCheckSmiThroughPhi(
&it, header, pre_header, current->AsCheckSmi());
}
}
}
}
}
}
static bool IsLoadEliminationCandidate(Definition* def) {
// Immutable loads (not affected by side effects) are handled
// in the DominatorBasedCSE pass.
// TODO(fschneider): Extend to other load instructions.
return (def->IsLoadField() && def->AffectedBySideEffect())
|| def->IsLoadIndexed();
}
static intptr_t ComputeLoadOffsetInWords(Definition* defn) {
if (defn->IsLoadIndexed()) {
// We are assuming that LoadField is never used to load the first word.
return 0;
}
LoadFieldInstr* load_field = defn->AsLoadField();
if (load_field != NULL) {
const intptr_t idx = load_field->offset_in_bytes() / kWordSize;
ASSERT(idx > 0);
return idx;
}
UNREACHABLE();
return 0;
}
static bool IsInterferingStore(Instruction* instr,
intptr_t* offset_in_words) {
if (instr->IsStoreIndexed()) {
// We are assuming that LoadField is never used to load the first word.
*offset_in_words = 0;
return true;
}
StoreInstanceFieldInstr* store_instance_field = instr->AsStoreInstanceField();
if (store_instance_field != NULL) {
ASSERT(store_instance_field->field().Offset() != 0);
*offset_in_words = store_instance_field->field().Offset() / kWordSize;
return true;
}
StoreVMFieldInstr* store_vm_field = instr->AsStoreVMField();
if (store_vm_field != NULL) {
ASSERT(store_vm_field->offset_in_bytes() != 0);
*offset_in_words = store_vm_field->offset_in_bytes() / kWordSize;
return true;
}
return false;
}
static Definition* GetStoredValue(Instruction* instr) {
if (instr->IsStoreIndexed()) {
return instr->AsStoreIndexed()->value()->definition();
}
StoreInstanceFieldInstr* store_instance_field = instr->AsStoreInstanceField();
if (store_instance_field != NULL) {
return store_instance_field->value()->definition();
}
StoreVMFieldInstr* store_vm_field = instr->AsStoreVMField();
if (store_vm_field != NULL) {
return store_vm_field->value()->definition();
}
UNREACHABLE(); // Should only be called for supported store instructions.
return NULL;
}
// KeyValueTrait used for numbering of loads. Allows to lookup loads
// corresponding to stores.
class LoadKeyValueTrait {
public:
typedef Definition* Value;
typedef Definition* Key;
typedef Definition* Pair;
static Key KeyOf(Pair kv) {
return kv;
}
static Value ValueOf(Pair kv) {
return kv;
}
static inline intptr_t Hashcode(Key key) {
intptr_t object = 0;
intptr_t location = 0;
if (key->IsLoadIndexed()) {
LoadIndexedInstr* load_indexed = key->AsLoadIndexed();
object = load_indexed->array()->definition()->ssa_temp_index();
location = load_indexed->index()->definition()->ssa_temp_index();
} else if (key->IsStoreIndexed()) {
StoreIndexedInstr* store_indexed = key->AsStoreIndexed();
object = store_indexed->array()->definition()->ssa_temp_index();
location = store_indexed->index()->definition()->ssa_temp_index();
} else if (key->IsLoadField()) {
LoadFieldInstr* load_field = key->AsLoadField();
object = load_field->value()->definition()->ssa_temp_index();
location = load_field->offset_in_bytes();
} else if (key->IsStoreInstanceField()) {
StoreInstanceFieldInstr* store_field = key->AsStoreInstanceField();
object = store_field->instance()->definition()->ssa_temp_index();
location = store_field->field().Offset();
} else if (key->IsStoreVMField()) {
StoreVMFieldInstr* store_field = key->AsStoreVMField();
object = store_field->dest()->definition()->ssa_temp_index();
location = store_field->offset_in_bytes();
}
return object * 31 + location;
}
static inline bool IsKeyEqual(Pair kv, Key key) {
if (kv->Equals(key)) return true;
if (kv->IsLoadIndexed()) {
if (key->IsStoreIndexed()) {
LoadIndexedInstr* load_indexed = kv->AsLoadIndexed();
StoreIndexedInstr* store_indexed = key->AsStoreIndexed();
return load_indexed->array()->Equals(store_indexed->array()) &&
load_indexed->index()->Equals(store_indexed->index());
}
return false;
}
ASSERT(kv->IsLoadField());
LoadFieldInstr* load_field = kv->AsLoadField();
if (key->IsStoreVMField()) {
StoreVMFieldInstr* store_field = key->AsStoreVMField();
return load_field->value()->Equals(store_field->dest()) &&
(load_field->offset_in_bytes() == store_field->offset_in_bytes());
} else if (key->IsStoreInstanceField()) {
StoreInstanceFieldInstr* store_field = key->AsStoreInstanceField();
return load_field->value()->Equals(store_field->instance()) &&
(load_field->offset_in_bytes() == store_field->field().Offset());
}
return false;
}
};
static intptr_t NumberLoadExpressions(
FlowGraph* graph,
DirectChainedHashMap<LoadKeyValueTrait>* map,
GrowableArray<BitVector*>* kill_by_offs) {
intptr_t expr_id = 0;
// Loads representing different expression ids will be collected and
// used to build per offset kill sets.
GrowableArray<Definition*> loads(10);
for (BlockIterator it = graph->reverse_postorder_iterator();
!it.Done();
it.Advance()) {
BlockEntryInstr* block = it.Current();
for (ForwardInstructionIterator instr_it(block);
!instr_it.Done();
instr_it.Advance()) {
Definition* defn = instr_it.Current()->AsDefinition();
if ((defn == NULL) || !IsLoadEliminationCandidate(defn)) {
continue;
}
Definition* result = map->Lookup(defn);
if (result == NULL) {
map->Insert(defn);
defn->set_expr_id(expr_id++);
loads.Add(defn);
} else {
defn->set_expr_id(result->expr_id());
}
}
}
// Build per offset kill sets. Any store interferes only with loads from
// the same offset.
for (intptr_t i = 0; i < loads.length(); i++) {
Definition* defn = loads[i];
const intptr_t offset_in_words = ComputeLoadOffsetInWords(defn);
while (kill_by_offs->length() <= offset_in_words) {
kill_by_offs->Add(NULL);
}
if ((*kill_by_offs)[offset_in_words] == NULL) {
(*kill_by_offs)[offset_in_words] = new BitVector(expr_id);
}
(*kill_by_offs)[offset_in_words]->Add(defn->expr_id());
}
return expr_id;
}
class LoadOptimizer : public ValueObject {
public:
LoadOptimizer(FlowGraph* graph,
intptr_t max_expr_id,
DirectChainedHashMap<LoadKeyValueTrait>* map,
const GrowableArray<BitVector*>& kill_by_offset)
: graph_(graph),
map_(map),
max_expr_id_(max_expr_id),
kill_by_offset_(kill_by_offset),
in_(graph_->preorder().length()),
out_(graph_->preorder().length()),
gen_(graph_->preorder().length()),
kill_(graph_->preorder().length()),
exposed_values_(graph_->preorder().length()),
out_values_(graph_->preorder().length()),
phis_(5),
worklist_(5),
in_worklist_(NULL) {
const intptr_t num_blocks = graph_->preorder().length();
for (intptr_t i = 0; i < num_blocks; i++) {
out_.Add(new BitVector(max_expr_id_));
gen_.Add(new BitVector(max_expr_id_));
kill_.Add(new BitVector(max_expr_id_));
in_.Add(new BitVector(max_expr_id_));
exposed_values_.Add(NULL);
out_values_.Add(NULL);
}
}
void Optimize() {
ComputeInitialSets();
ComputeOutValues();
ForwardLoads();
EmitPhis();
}
private:
// Compute sets of loads generated and killed by each block.
// Additionally compute upwards exposed and generated loads for each block.
// Exposed loads are those that can be replaced if a corresponding
// reaching load will be found.
// Loads that are locally redundant will be replaced as we go through
// instructions.
void ComputeInitialSets() {
for (BlockIterator block_it = graph_->reverse_postorder_iterator();
!block_it.Done();
block_it.Advance()) {
BlockEntryInstr* block = block_it.Current();
const intptr_t preorder_number = block->preorder_number();
BitVector* kill = kill_[preorder_number];
BitVector* gen = gen_[preorder_number];
ZoneGrowableArray<Definition*>* exposed_values = NULL;
ZoneGrowableArray<Definition*>* out_values = NULL;
for (ForwardInstructionIterator instr_it(block);
!instr_it.Done();
instr_it.Advance()) {
Instruction* instr = instr_it.Current();
intptr_t offset_in_words = 0;
if (IsInterferingStore(instr, &offset_in_words)) {
// Interfering stores kill only loads from the same offset.
if ((offset_in_words < kill_by_offset_.length()) &&
(kill_by_offset_[offset_in_words] != NULL)) {
kill->AddAll(kill_by_offset_[offset_in_words]);
// There is no need to clear out_values when clearing GEN set
// because only those values that are in the GEN set
// will ever be used.
gen->RemoveAll(kill_by_offset_[offset_in_words]);
// Only forward stores to normal arrays and float64 arrays
// to loads because other array stores (intXX/uintXX/float32)
// may implicitly convert the value stored.
StoreIndexedInstr* array_store = instr->AsStoreIndexed();
if (array_store == NULL ||
array_store->class_id() == kArrayCid ||
array_store->class_id() == kFloat64ArrayCid) {
Definition* load = map_->Lookup(instr->AsDefinition());
if (load != NULL) {
// Store has a corresponding numbered load. Try forwarding
// stored value to it.
gen->Add(load->expr_id());
if (out_values == NULL) out_values = CreateBlockOutValues();
(*out_values)[load->expr_id()] = GetStoredValue(instr);
}
}
}
ASSERT(instr->IsDefinition() &&
!IsLoadEliminationCandidate(instr->AsDefinition()));
continue;
}
// Other instructions with side effects kill all loads.
if (instr->HasSideEffect()) {
kill->SetAll();
// There is no need to clear out_values when clearing GEN set
// because only those values that are in the GEN set
// will ever be used.
gen->Clear();
continue;
}
Definition* defn = instr->AsDefinition();
if ((defn == NULL) || !IsLoadEliminationCandidate(defn)) {
continue;
}
const intptr_t expr_id = defn->expr_id();
if (gen->Contains(expr_id)) {
// This is a locally redundant load.
ASSERT((out_values != NULL) && ((*out_values)[expr_id] != NULL));
Definition* replacement = (*out_values)[expr_id];
EnsureSSATempIndex(graph_, defn, replacement);
if (FLAG_trace_optimization) {
OS::Print("Replacing load v%"Pd" with v%"Pd"\n",
defn->ssa_temp_index(),
replacement->ssa_temp_index());
}
defn->ReplaceUsesWith(replacement);
instr_it.RemoveCurrentFromGraph();
continue;
} else if (!kill->Contains(expr_id)) {
// This is an exposed load: it is the first representative of a
// given expression id and it is not killed on the path from
// the block entry.
if (exposed_values == NULL) {
static const intptr_t kMaxExposedValuesInitialSize = 5;
exposed_values = new ZoneGrowableArray<Definition*>(
Utils::Minimum(kMaxExposedValuesInitialSize, max_expr_id_));
}
exposed_values->Add(defn);
}
gen->Add(expr_id);
if (out_values == NULL) out_values = CreateBlockOutValues();
(*out_values)[expr_id] = defn;
}
out_[preorder_number]->CopyFrom(gen);
exposed_values_[preorder_number] = exposed_values;
out_values_[preorder_number] = out_values;
}
}
// Compute OUT sets and corresponding out_values mappings by propagating them
// iteratively until fix point is reached.
// No replacement is done at this point and thus any out_value[expr_id] is
// changed at most once: from NULL to an actual value.
// When merging incoming loads we might need to create a phi.
// These phis are not inserted at the graph immediately because some of them
// might become redundant after load forwarding is done.
void ComputeOutValues() {
BitVector* temp = new BitVector(max_expr_id_);
bool changed = true;
while (changed) {
changed = false;
for (BlockIterator block_it = graph_->reverse_postorder_iterator();
!block_it.Done();
block_it.Advance()) {
BlockEntryInstr* block = block_it.Current();
const intptr_t preorder_number = block->preorder_number();
BitVector* block_in = in_[preorder_number];
BitVector* block_out = out_[preorder_number];
BitVector* block_kill = kill_[preorder_number];
BitVector* block_gen = gen_[preorder_number];
if (FLAG_trace_optimization) {
OS::Print("B%"Pd"", block->block_id());
block_in->Print();
block_out->Print();
block_kill->Print();
block_gen->Print();
OS::Print("\n");
}
ZoneGrowableArray<Definition*>* block_out_values =
out_values_[preorder_number];
// Compute block_in as the intersection of all out(p) where p
// is a predecessor of the current block.
if (block->IsGraphEntry()) {
temp->Clear();
} else {
// TODO(vegorov): this can be optimized for the case of a single
// predecessor.
// TODO(vegorov): this can be reordered to reduce amount of operations
// temp->CopyFrom(first_predecessor)
temp->SetAll();
ASSERT(block->PredecessorCount() > 0);
for (intptr_t i = 0; i < block->PredecessorCount(); i++) {
BlockEntryInstr* pred = block->PredecessorAt(i);
BitVector* pred_out = out_[pred->preorder_number()];
temp->Intersect(*pred_out);
}
}
if (!temp->Equals(*block_in)) {
// If IN set has changed propagate the change to OUT set.
block_in->CopyFrom(temp);
if (block_out->KillAndAdd(block_kill, block_in)) {
// If OUT set has changed then we have new values available out of
// the block. Compute these values creating phi where necessary.
for (BitVector::Iterator it(block_out);
!it.Done();
it.Advance()) {
const intptr_t expr_id = it.Current();
if (block_out_values == NULL) {
out_values_[preorder_number] = block_out_values =
CreateBlockOutValues();
}
if ((*block_out_values)[expr_id] == NULL) {
ASSERT(block->PredecessorCount() > 0);
(*block_out_values)[expr_id] =
MergeIncomingValues(block, expr_id);
}
}
changed = true;
}
}
if (FLAG_trace_optimization) {
OS::Print("after B%"Pd"", block->block_id());
block_in->Print();
block_out->Print();
block_kill->Print();
block_gen->Print();
OS::Print("\n");
}
}
}
}
// Compute incoming value for the given expression id.
// Will create a phi if different values are incoming from multiple
// predecessors.
Definition* MergeIncomingValues(BlockEntryInstr* block, intptr_t expr_id) {
// First check if the same value is coming in from all predecessors.
Definition* incoming = NULL;
for (intptr_t i = 0; i < block->PredecessorCount(); i++) {
BlockEntryInstr* pred = block->PredecessorAt(i);
ZoneGrowableArray<Definition*>* pred_out_values =
out_values_[pred->preorder_number()];
if (incoming == NULL) {
incoming = (*pred_out_values)[expr_id];
} else if (incoming != (*pred_out_values)[expr_id]) {
incoming = NULL;
break;
}
}
if (incoming != NULL) {
return incoming;
}
// Incoming values are different. Phi is required to merge.
PhiInstr* phi = new PhiInstr(
block->AsJoinEntry(), block->PredecessorCount());
for (intptr_t i = 0; i < block->PredecessorCount(); i++) {
BlockEntryInstr* pred = block->PredecessorAt(i);
ZoneGrowableArray<Definition*>* pred_out_values =
out_values_[pred->preorder_number()];
ASSERT((*pred_out_values)[expr_id] != NULL);
// Sets of outgoing values are not linked into use lists so
// they might contain values that were replaced and removed
// from the graph by this iteration.
// To prevent using them we additionally mark definitions themselves
// as replaced and store a pointer to the replacement.
Definition* replacement = (*pred_out_values)[expr_id]->Replacement();
Value* input = new Value(replacement);
phi->SetInputAt(i, input);
replacement->AddInputUse(input);
}
phi->set_ssa_temp_index(graph_->alloc_ssa_temp_index());
phis_.Add(phi); // Postpone phi insertion until after load forwarding.
return phi;
}
// Iterate over basic blocks and replace exposed loads with incoming
// values.
void ForwardLoads() {
for (BlockIterator block_it = graph_->reverse_postorder_iterator();
!block_it.Done();
block_it.Advance()) {
BlockEntryInstr* block = block_it.Current();
ZoneGrowableArray<Definition*>* loads =
exposed_values_[block->preorder_number()];
if (loads == NULL) continue; // No exposed loads.
BitVector* in = in_[block->preorder_number()];
for (intptr_t i = 0; i < loads->length(); i++) {
Definition* load = (*loads)[i];
if (!in->Contains(load->expr_id())) continue; // No incoming value.
Definition* replacement = MergeIncomingValues(block, load->expr_id());
// Sets of outgoing values are not linked into use lists so
// they might contain values that were replace and removed
// from the graph by this iteration.
// To prevent using them we additionally mark definitions themselves
// as replaced and store a pointer to the replacement.
replacement = replacement->Replacement();
if (load != replacement) {
EnsureSSATempIndex(graph_, load, replacement);
if (FLAG_trace_optimization) {
OS::Print("Replacing load v%"Pd" with v%"Pd"\n",
load->ssa_temp_index(),
replacement->ssa_temp_index());
}
load->ReplaceUsesWith(replacement);
load->RemoveFromGraph();
load->SetReplacement(replacement);
}
}
}
}
// Check if the given phi take the same value on all code paths.
// Eliminate it as redundant if this is the case.
// When analyzing phi operands assumes that only generated during
// this load phase can be redundant. They can be distinguished because
// they are not marked alive.
// TODO(vegorov): move this into a separate phase over all phis.
bool EliminateRedundantPhi(PhiInstr* phi) {
Definition* value = NULL; // Possible value of this phi.
worklist_.Clear();
if (in_worklist_ == NULL) {
in_worklist_ = new BitVector(graph_->current_ssa_temp_index());
} else {
in_worklist_->Clear();
}
worklist_.Add(phi);
in_worklist_->Add(phi->ssa_temp_index());
for (intptr_t i = 0; i < worklist_.length(); i++) {
PhiInstr* phi = worklist_[i];
for (intptr_t i = 0; i < phi->InputCount(); i++) {
Definition* input = phi->InputAt(i)->definition();
if (input == phi) continue;
PhiInstr* phi_input = input->AsPhi();
if ((phi_input != NULL) && !phi_input->is_alive()) {
if (!in_worklist_->Contains(phi_input->ssa_temp_index())) {
worklist_.Add(phi_input);
in_worklist_->Add(phi_input->ssa_temp_index());
}
continue;
}
if (value == NULL) {
value = input;
} else if (value != input) {
return false; // This phi is not redundant.
}
}
}
// All phis in the worklist are redundant and have the same computed
// value on all code paths.
ASSERT(value != NULL);
for (intptr_t i = 0; i < worklist_.length(); i++) {
worklist_[i]->ReplaceUsesWith(value);
}
return true;
}
// Phis have not yet been inserted into the graph but they have uses of
// their inputs. Insert the non-redundant ones and clear the input uses
// of the redundant ones.
void EmitPhis() {
for (intptr_t i = 0; i < phis_.length(); i++) {
PhiInstr* phi = phis_[i];
if (phi->HasUses() && !EliminateRedundantPhi(phi)) {
phi->mark_alive();
phi->block()->InsertPhi(phi);
} else {
for (intptr_t j = phi->InputCount() - 1; j >= 0; --j) {
phi->InputAt(j)->RemoveFromUseList();
}
}
}
}
ZoneGrowableArray<Definition*>* CreateBlockOutValues() {
ZoneGrowableArray<Definition*>* out =
new ZoneGrowableArray<Definition*>(max_expr_id_);
for (intptr_t i = 0; i < max_expr_id_; i++) {
out->Add(NULL);
}
return out;
}
FlowGraph* graph_;
DirectChainedHashMap<LoadKeyValueTrait>* map_;
const intptr_t max_expr_id_;
// Mapping between field offsets in words and expression ids of loads from
// that offset.
const GrowableArray<BitVector*>& kill_by_offset_;
// Per block sets of expression ids for loads that are: incoming (available
// on the entry), outgoing (available on the exit), generated and killed.
GrowableArray<BitVector*> in_;
GrowableArray<BitVector*> out_;
GrowableArray<BitVector*> gen_;
GrowableArray<BitVector*> kill_;
// Per block list of upwards exposed loads.
GrowableArray<ZoneGrowableArray<Definition*>*> exposed_values_;
// Per block mappings between expression ids and outgoing definitions that
// represent those ids.
GrowableArray<ZoneGrowableArray<Definition*>*> out_values_;
// List of phis generated during ComputeOutValues and ForwardLoads.
// Some of these phis might be redundant and thus a separate pass is
// needed to emit only non-redundant ones.
GrowableArray<PhiInstr*> phis_;
// Auxiliary worklist used by redundant phi elimination.
GrowableArray<PhiInstr*> worklist_;
BitVector* in_worklist_;
DISALLOW_COPY_AND_ASSIGN(LoadOptimizer);
};
bool DominatorBasedCSE::Optimize(FlowGraph* graph) {
bool changed = false;
if (FLAG_load_cse) {
GrowableArray<BitVector*> kill_by_offs(10);
DirectChainedHashMap<LoadKeyValueTrait> map;
const intptr_t max_expr_id =
NumberLoadExpressions(graph, &map, &kill_by_offs);
if (max_expr_id > 0) {
LoadOptimizer load_optimizer(graph, max_expr_id, &map, kill_by_offs);
load_optimizer.Optimize();
}
}
DirectChainedHashMap<PointerKeyValueTrait<Instruction> > map;
changed = OptimizeRecursive(graph, graph->graph_entry(), &map) || changed;
return changed;
}
bool DominatorBasedCSE::OptimizeRecursive(
FlowGraph* graph,
BlockEntryInstr* block,
DirectChainedHashMap<PointerKeyValueTrait<Instruction> >* map) {
bool changed = false;
for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
Instruction* current = it.Current();
if (current->AffectedBySideEffect()) continue;
Instruction* replacement = map->Lookup(current);
if (replacement == NULL) {
map->Insert(current);
continue;
}
// Replace current with lookup result.
ReplaceCurrentInstruction(&it, current, replacement, graph);
changed = true;
}
// Process children in the dominator tree recursively.
intptr_t num_children = block->dominated_blocks().length();
for (intptr_t i = 0; i < num_children; ++i) {
BlockEntryInstr* child = block->dominated_blocks()[i];
if (i < num_children - 1) {
// Copy map.
DirectChainedHashMap<PointerKeyValueTrait<Instruction> > child_map(*map);
changed = OptimizeRecursive(graph, child, &child_map) || changed;
} else {
// Reuse map for the last child.
changed = OptimizeRecursive(graph, child, map) || changed;
}
}
return changed;
}
ConstantPropagator::ConstantPropagator(
FlowGraph* graph,
const GrowableArray<BlockEntryInstr*>& ignored)
: FlowGraphVisitor(ignored),
graph_(graph),
unknown_(Object::transition_sentinel()),
non_constant_(Object::sentinel()),
reachable_(new BitVector(graph->preorder().length())),
definition_marks_(new BitVector(graph->max_virtual_register_number())),
block_worklist_(),
definition_worklist_() {}
void ConstantPropagator::Optimize(FlowGraph* graph) {
GrowableArray<BlockEntryInstr*> ignored;
ConstantPropagator cp(graph, ignored);
cp.Analyze();
cp.Transform();
}
void ConstantPropagator::SetReachable(BlockEntryInstr* block) {
if (!reachable_->Contains(block->preorder_number())) {
reachable_->Add(block->preorder_number());
block_worklist_.Add(block);
}
}
void ConstantPropagator::SetValue(Definition* definition, const Object& value) {
// We would like to assert we only go up (toward non-constant) in the lattice.
//
// ASSERT(IsUnknown(definition->constant_value()) ||
// IsNonConstant(value) ||
// (definition->constant_value().raw() == value.raw()));
//
// But the final disjunct is not true (e.g., mint or double constants are
// heap-allocated and so not necessarily pointer-equal on each iteration).
if (definition->constant_value().raw() != value.raw()) {
definition->constant_value() = value.raw();
if (definition->input_use_list() != NULL) {
ASSERT(definition->HasSSATemp());
if (!definition_marks_->Contains(definition->ssa_temp_index())) {
definition_worklist_.Add(definition);
definition_marks_->Add(definition->ssa_temp_index());
}
}
}
}
// Compute the join of two values in the lattice, assign it to the first.
void ConstantPropagator::Join(Object* left, const Object& right) {
// Join(non-constant, X) = non-constant
// Join(X, unknown) = X
if (IsNonConstant(*left) || IsUnknown(right)) return;
// Join(unknown, X) = X
// Join(X, non-constant) = non-constant
if (IsUnknown(*left) || IsNonConstant(right)) {
*left = right.raw();
return;
}
// Join(X, X) = X
// TODO(kmillikin): support equality for doubles, mints, etc.
if (left->raw() == right.raw()) return;
// Join(X, Y) = non-constant
*left = non_constant_.raw();
}
// --------------------------------------------------------------------------
// Analysis of blocks. Called at most once per block. The block is already
// marked as reachable. All instructions in the block are analyzed.
void ConstantPropagator::VisitGraphEntry(GraphEntryInstr* block) {
const GrowableArray<Definition*>& defs = *block->initial_definitions();
for (intptr_t i = 0; i < defs.length(); ++i) {
defs[i]->Accept(this);
}
ASSERT(ForwardInstructionIterator(block).Done());
SetReachable(block->normal_entry());
}
void ConstantPropagator::VisitJoinEntry(JoinEntryInstr* block) {
// Phis are visited when visiting Goto at a predecessor. See VisitGoto.
for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
it.Current()->Accept(this);
}
}
void ConstantPropagator::VisitTargetEntry(TargetEntryInstr* block) {
for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
it.Current()->Accept(this);
}
}
void ConstantPropagator::VisitParallelMove(ParallelMoveInstr* instr) {
// Parallel moves have not yet been inserted in the graph.
UNREACHABLE();
}
// --------------------------------------------------------------------------
// Analysis of control instructions. Unconditional successors are
// reachable. Conditional successors are reachable depending on the
// constant value of the condition.
void ConstantPropagator::VisitReturn(ReturnInstr* instr) {
// Nothing to do.
}
void ConstantPropagator::VisitThrow(ThrowInstr* instr) {
// Nothing to do.
}
void ConstantPropagator::VisitReThrow(ReThrowInstr* instr) {
// Nothing to do.
}
void ConstantPropagator::VisitGoto(GotoInstr* instr) {
SetReachable(instr->successor());
// Phi value depends on the reachability of a predecessor. We have
// to revisit phis every time a predecessor becomes reachable.
for (PhiIterator it(instr->successor()); !it.Done(); it.Advance()) {
it.Current()->Accept(this);
}
}
void ConstantPropagator::VisitBranch(BranchInstr* instr) {
instr->comparison()->Accept(this);
// The successors may be reachable, but only if this instruction is. (We
// might be analyzing it because the constant value of one of its inputs
// has changed.)
if (reachable_->Contains(instr->GetBlock()->preorder_number())) {
const Object& value = instr->comparison()->constant_value();
if (IsNonConstant(value)) {
SetReachable(instr->true_successor());
SetReachable(instr->false_successor());
} else if (value.raw() == Bool::True().raw()) {
SetReachable(instr->true_successor());
} else if (!IsUnknown(value)) { // Any other constant.
SetReachable(instr->false_successor());
}
}
}
// --------------------------------------------------------------------------
// Analysis of non-definition instructions. They do not have values so they
// cannot have constant values.
void ConstantPropagator::VisitStoreContext(StoreContextInstr* instr) { }
void ConstantPropagator::VisitChainContext(ChainContextInstr* instr) { }
void ConstantPropagator::VisitCatchEntry(CatchEntryInstr* instr) { }
void ConstantPropagator::VisitCheckStackOverflow(
CheckStackOverflowInstr* instr) { }
void ConstantPropagator::VisitCheckClass(CheckClassInstr* instr) { }
void ConstantPropagator::VisitCheckSmi(CheckSmiInstr* instr) { }
void ConstantPropagator::VisitCheckEitherNonSmi(
CheckEitherNonSmiInstr* instr) { }
void ConstantPropagator::VisitCheckArrayBound(CheckArrayBoundInstr* instr) { }
// --------------------------------------------------------------------------
// Analysis of definitions. Compute the constant value. If it has changed
// and the definition has input uses, add the definition to the definition
// worklist so that the used can be processed.
void ConstantPropagator::VisitPhi(PhiInstr* instr) {
// Compute the join over all the reachable predecessor values.
JoinEntryInstr* block = instr->block();
Object& value = Object::ZoneHandle(Unknown());
for (intptr_t pred_idx = 0; pred_idx < instr->InputCount(); ++pred_idx) {
if (reachable_->Contains(
block->PredecessorAt(pred_idx)->preorder_number())) {
Join(&value,
instr->InputAt(pred_idx)->definition()->constant_value());
}
}
SetValue(instr, value);
}
void ConstantPropagator::VisitParameter(ParameterInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitPushArgument(PushArgumentInstr* instr) {
SetValue(instr, instr->value()->definition()->constant_value());
}
void ConstantPropagator::VisitAssertAssignable(AssertAssignableInstr* instr) {
const Object& value = instr->value()->definition()->constant_value();
if (IsNonConstant(value)) {
SetValue(instr, non_constant_);
} else if (IsConstant(value)) {
// We are ignoring the instantiator and instantiator_type_arguments, but
// still monotonic and safe.
// TODO(kmillikin): Handle constants.
SetValue(instr, non_constant_);
}
}
void ConstantPropagator::VisitAssertBoolean(AssertBooleanInstr* instr) {
const Object& value = instr->value()->definition()->constant_value();
if (IsNonConstant(value)) {
SetValue(instr, non_constant_);
} else if (IsConstant(value)) {
// TODO(kmillikin): Handle assertion.
SetValue(instr, non_constant_);
}
}
void ConstantPropagator::VisitArgumentDefinitionTest(
ArgumentDefinitionTestInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitCurrentContext(CurrentContextInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitClosureCall(ClosureCallInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitInstanceCall(InstanceCallInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitPolymorphicInstanceCall(
PolymorphicInstanceCallInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitStaticCall(StaticCallInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitLoadLocal(LoadLocalInstr* instr) {
// Instruction is eliminated when translating to SSA.
UNREACHABLE();
}
void ConstantPropagator::VisitStoreLocal(StoreLocalInstr* instr) {
// Instruction is eliminated when translating to SSA.
UNREACHABLE();
}
void ConstantPropagator::VisitStrictCompare(StrictCompareInstr* instr) {
const Object& left = instr->left()->definition()->constant_value();
const Object& right = instr->right()->definition()->constant_value();
if (IsNonConstant(left) || IsNonConstant(right)) {
// TODO(vegorov): incorporate nullability information into the lattice.
if ((left.IsNull() && instr->right()->Type()->HasDecidableNullability()) ||
(right.IsNull() && instr->left()->Type()->HasDecidableNullability())) {
bool result = left.IsNull() ? instr->right()->Type()->IsNull()
: instr->left()->Type()->IsNull();
if (instr->kind() == Token::kNE_STRICT) result = !result;
SetValue(instr, result ? Bool::True() : Bool::False());
} else {
SetValue(instr, non_constant_);
}
} else if (IsConstant(left) && IsConstant(right)) {
bool result = (left.raw() == right.raw());
if (instr->kind() == Token::kNE_STRICT) result = !result;
SetValue(instr, result ? Bool::True() : Bool::False());
}
}
static bool CompareIntegers(Token::Kind kind,
const Integer& left,
const Integer& right) {
const int result = left.CompareWith(right);
switch (kind) {
case Token::kEQ: return (result == 0);
case Token::kNE: return (result != 0);
case Token::kLT: return (result < 0);
case Token::kGT: return (result > 0);
case Token::kLTE: return (result <= 0);
case Token::kGTE: return (result >= 0);
default:
UNREACHABLE();
return false;
}
}
void ConstantPropagator::VisitEqualityCompare(EqualityCompareInstr* instr) {
const Object& left = instr->left()->definition()->constant_value();
const Object& right = instr->right()->definition()->constant_value();
if (IsNonConstant(left) || IsNonConstant(right)) {
SetValue(instr, non_constant_);
} else if (IsConstant(left) && IsConstant(right)) {
if (left.IsInteger() && right.IsInteger()) {
const bool result = CompareIntegers(instr->kind(),
Integer::Cast(left),
Integer::Cast(right));
SetValue(instr, result ? Bool::True() : Bool::False());
} else {
SetValue(instr, non_constant_);
}
}
}
void ConstantPropagator::VisitRelationalOp(RelationalOpInstr* instr) {
const Object& left = instr->left()->definition()->constant_value();
const Object& right = instr->right()->definition()->constant_value();
if (IsNonConstant(left) || IsNonConstant(right)) {
SetValue(instr, non_constant_);
} else if (IsConstant(left) && IsConstant(right)) {
if (left.IsInteger() && right.IsInteger()) {
const bool result = CompareIntegers(instr->kind(),
Integer::Cast(left),
Integer::Cast(right));
SetValue(instr, result ? Bool::True() : Bool::False());
} else {
SetValue(instr, non_constant_);
}
}
}
void ConstantPropagator::VisitNativeCall(NativeCallInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitStringFromCharCode(
StringFromCharCodeInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitLoadIndexed(LoadIndexedInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitStoreIndexed(StoreIndexedInstr* instr) {
SetValue(instr, instr->value()->definition()->constant_value());
}
void ConstantPropagator::VisitStoreInstanceField(
StoreInstanceFieldInstr* instr) {
SetValue(instr, instr->value()->definition()->constant_value());
}
void ConstantPropagator::VisitLoadStaticField(LoadStaticFieldInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitStoreStaticField(StoreStaticFieldInstr* instr) {
SetValue(instr, instr->value()->definition()->constant_value());
}
void ConstantPropagator::VisitBooleanNegate(BooleanNegateInstr* instr) {
const Object& value = instr->value()->definition()->constant_value();
if (IsNonConstant(value)) {
SetValue(instr, non_constant_);
} else if (IsConstant(value)) {
bool val = value.raw() != Bool::True().raw();
SetValue(instr, val ? Bool::True() : Bool::False());
}
}
void ConstantPropagator::VisitInstanceOf(InstanceOfInstr* instr) {
const Object& value = instr->value()->definition()->constant_value();
if (IsNonConstant(value)) {
SetValue(instr, non_constant_);
} else if (IsConstant(value)) {
// TODO(kmillikin): Handle instanceof on constants.
SetValue(instr, non_constant_);
}
}
void ConstantPropagator::VisitCreateArray(CreateArrayInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitCreateClosure(CreateClosureInstr* instr) {
// TODO(kmillikin): Treat closures as constants.
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitAllocateObject(AllocateObjectInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitAllocateObjectWithBoundsCheck(
AllocateObjectWithBoundsCheckInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitLoadField(LoadFieldInstr* instr) {
if ((instr->recognized_kind() == MethodRecognizer::kObjectArrayLength) &&
(instr->value()->definition()->IsCreateArray())) {
const intptr_t length =
instr->value()->definition()->AsCreateArray()->num_elements();
const Object& result = Smi::ZoneHandle(Smi::New(length));
SetValue(instr, result);
return;
}
if (instr->IsImmutableLengthLoad()) {
ConstantInstr* constant = instr->value()->definition()->AsConstant();
if (constant != NULL) {
if (constant->value().IsString()) {
SetValue(instr, Smi::ZoneHandle(
Smi::New(String::Cast(constant->value()).Length())));
return;
}
if (constant->value().IsArray()) {
SetValue(instr, Smi::ZoneHandle(
Smi::New(Array::Cast(constant->value()).Length())));
return;
}
}
}
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitStoreVMField(StoreVMFieldInstr* instr) {
SetValue(instr, instr->value()->definition()->constant_value());
}
void ConstantPropagator::VisitInstantiateTypeArguments(
InstantiateTypeArgumentsInstr* instr) {
const Object& object =
instr->instantiator()->definition()->constant_value();
if (IsNonConstant(object)) {
SetValue(instr, non_constant_);
return;
}
if (IsConstant(object)) {
const intptr_t len = instr->type_arguments().Length();
if (instr->type_arguments().IsRawInstantiatedRaw(len) &&
object.IsNull()) {
SetValue(instr, object);
return;
}
if (instr->type_arguments().IsUninstantiatedIdentity() &&
!object.IsNull() &&
object.IsTypeArguments() &&
(TypeArguments::Cast(object).Length() == len)) {
SetValue(instr, object);
return;
}
SetValue(instr, non_constant_);
}
}
void ConstantPropagator::VisitExtractConstructorTypeArguments(
ExtractConstructorTypeArgumentsInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitExtractConstructorInstantiator(
ExtractConstructorInstantiatorInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitAllocateContext(AllocateContextInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitCloneContext(CloneContextInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitBinarySmiOp(BinarySmiOpInstr* instr) {
const Object& left = instr->left()->definition()->constant_value();
const Object& right = instr->right()->definition()->constant_value();
if (IsNonConstant(left) || IsNonConstant(right)) {
SetValue(instr, non_constant_);
} else if (IsConstant(left) && IsConstant(right)) {
if (left.IsSmi() && right.IsSmi()) {
const Smi& left_smi = Smi::Cast(left);
const Smi& right_smi = Smi::Cast(right);
switch (instr->op_kind()) {
case Token::kADD:
case Token::kSUB:
case Token::kMUL:
case Token::kTRUNCDIV:
case Token::kMOD: {
const Object& result = Integer::ZoneHandle(
left_smi.ArithmeticOp(instr->op_kind(), right_smi));
SetValue(instr, result);
break;
}
case Token::kSHL:
case Token::kSHR: {
const Object& result = Integer::ZoneHandle(
left_smi.ShiftOp(instr->op_kind(), right_smi));
SetValue(instr, result);
break;
}
case Token::kBIT_AND:
case Token::kBIT_OR:
case Token::kBIT_XOR: {
const Object& result = Integer::ZoneHandle(
left_smi.BitOp(instr->op_kind(), right_smi));
SetValue(instr, result);
break;
}
default:
// TODO(kmillikin): support other smi operations.
SetValue(instr, non_constant_);
}
} else {
// TODO(kmillikin): support other types.
SetValue(instr, non_constant_);
}
}
}
void ConstantPropagator::VisitBoxInteger(BoxIntegerInstr* instr) {
// TODO(kmillikin): Handle box operation.
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitUnboxInteger(UnboxIntegerInstr* instr) {
// TODO(kmillikin): Handle unbox operation.
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitBinaryMintOp(
BinaryMintOpInstr* instr) {
// TODO(kmillikin): Handle binary operations.
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitShiftMintOp(
ShiftMintOpInstr* instr) {
// TODO(kmillikin): Handle shift operations.
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitUnaryMintOp(
UnaryMintOpInstr* instr) {
// TODO(kmillikin): Handle unary operations.
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitUnarySmiOp(UnarySmiOpInstr* instr) {
const Object& value = instr->value()->definition()->constant_value();
if (IsNonConstant(value)) {
SetValue(instr, non_constant_);
} else if (IsConstant(value)) {
// TODO(kmillikin): Handle unary operations.
SetValue(instr, non_constant_);
}
}
void ConstantPropagator::VisitSmiToDouble(SmiToDoubleInstr* instr) {
// TODO(kmillikin): Handle conversion.
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitDoubleToInteger(DoubleToIntegerInstr* instr) {
// TODO(kmillikin): Handle conversion.
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitDoubleToSmi(DoubleToSmiInstr* instr) {
// TODO(kmillikin): Handle conversion.
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitDoubleToDouble(DoubleToDoubleInstr* instr) {
// TODO(kmillikin): Handle conversion.
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitInvokeMathCFunction(
InvokeMathCFunctionInstr* instr) {
// TODO(kmillikin): Handle conversion.
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitConstant(ConstantInstr* instr) {
SetValue(instr, instr->value());
}
void ConstantPropagator::VisitConstraint(ConstraintInstr* instr) {
// Should not be used outside of range analysis.
UNREACHABLE();
}
void ConstantPropagator::VisitBinaryDoubleOp(
BinaryDoubleOpInstr* instr) {
const Object& left = instr->left()->definition()->constant_value();
const Object& right = instr->right()->definition()->constant_value();
if (IsNonConstant(left) || IsNonConstant(right)) {
SetValue(instr, non_constant_);
} else if (IsConstant(left) && IsConstant(right)) {
// TODO(kmillikin): Handle binary operation.
SetValue(instr, non_constant_);
}
}
void ConstantPropagator::VisitMathSqrt(MathSqrtInstr* instr) {
const Object& value = instr->value()->definition()->constant_value();
if (IsNonConstant(value)) {
SetValue(instr, non_constant_);
} else if (IsConstant(value)) {
// TODO(kmillikin): Handle sqrt.
SetValue(instr, non_constant_);
}
}
void ConstantPropagator::VisitUnboxDouble(UnboxDoubleInstr* instr) {
const Object& value = instr->value()->definition()->constant_value();
if (IsNonConstant(value)) {
SetValue(instr, non_constant_);
} else if (IsConstant(value)) {
// TODO(kmillikin): Handle conversion.
SetValue(instr, non_constant_);
}
}
void ConstantPropagator::VisitBoxDouble(BoxDoubleInstr* instr) {
const Object& value = instr->value()->definition()->constant_value();
if (IsNonConstant(value)) {
SetValue(instr, non_constant_);
} else if (IsConstant(value)) {
// TODO(kmillikin): Handle conversion.
SetValue(instr, non_constant_);
}
}
void ConstantPropagator::Analyze() {
GraphEntryInstr* entry = graph_->graph_entry();
reachable_->Add(entry->preorder_number());
block_worklist_.Add(entry);
while (true) {
if (block_worklist_.is_empty()) {
if (definition_worklist_.is_empty()) break;
Definition* definition = definition_worklist_.RemoveLast();
definition_marks_->Remove(definition->ssa_temp_index());
Value* use = definition->input_use_list();
while (use != NULL) {
use->instruction()->Accept(this);
use = use->next_use();
}
} else {
BlockEntryInstr* block = block_worklist_.RemoveLast();
block->Accept(this);
}
}
}
void ConstantPropagator::Transform() {
if (FLAG_trace_constant_propagation) {
OS::Print("\n==== Before constant propagation ====\n");
FlowGraphPrinter printer(*graph_);
printer.PrintBlocks();
}
GrowableArray<PhiInstr*> redundant_phis(10);
// We will recompute dominators, block ordering, block ids, block last
// instructions, previous pointers, predecessors, etc. after eliminating
// unreachable code. We do not maintain those properties during the
// transformation.
for (BlockIterator b = graph_->reverse_postorder_iterator();
!b.Done();
b.Advance()) {
BlockEntryInstr* block = b.Current();
JoinEntryInstr* join = block->AsJoinEntry();
if (!reachable_->Contains(block->preorder_number())) {
if (FLAG_trace_constant_propagation) {
OS::Print("Unreachable B%"Pd"\n", block->block_id());
}
// Remove all uses in unreachable blocks.
if (join != NULL) {
for (PhiIterator it(join); !it.Done(); it.Advance()) {
it.Current()->UnuseAllInputs();
}
}
for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
it.Current()->UnuseAllInputs();
}
continue;
}
if (join != NULL) {
// Remove phi inputs corresponding to unreachable predecessor blocks.
// Predecessors will be recomputed (in block id order) after removing
// unreachable code so we merely have to keep the phi inputs in order.
ZoneGrowableArray<PhiInstr*>* phis = join->phis();
if ((phis != NULL) && !phis->is_empty()) {
intptr_t pred_count = join->PredecessorCount();
intptr_t live_count = 0;
for (intptr_t pred_idx = 0; pred_idx < pred_count; ++pred_idx) {
if (reachable_->Contains(
join->PredecessorAt(pred_idx)->preorder_number())) {
if (live_count < pred_idx) {
for (PhiIterator it(join); !it.Done(); it.Advance()) {
PhiInstr* phi = it.Current();
ASSERT(phi != NULL);
phi->SetInputAt(live_count, phi->InputAt(pred_idx));
}
}
++live_count;
} else {
for (PhiIterator it(join); !it.Done(); it.Advance()) {
PhiInstr* phi = it.Current();
ASSERT(phi != NULL);
phi->InputAt(pred_idx)->RemoveFromUseList();
}
}
}
if (live_count < pred_count) {
intptr_t to_idx = 0;
for (intptr_t from_idx = 0; from_idx < phis->length(); ++from_idx) {
PhiInstr* phi = (*phis)[from_idx];
ASSERT(phi != NULL);
if (FLAG_remove_redundant_phis && (live_count == 1)) {
Value* input = phi->InputAt(0);
phi->ReplaceUsesWith(input->definition());
input->RemoveFromUseList();
} else {
phi->inputs_.TruncateTo(live_count);
(*phis)[to_idx++] = phi;
}
}
if (to_idx == 0) {
join->phis_ = NULL;
} else {
phis->TruncateTo(to_idx);
}
}
}
}
for (ForwardInstructionIterator i(block); !i.Done(); i.Advance()) {
Definition* defn = i.Current()->AsDefinition();
// Replace constant-valued instructions without observable side
// effects. Do this for smis only to avoid having to copy other
// objects into the heap's old generation.
if ((defn != NULL) &&
IsConstant(defn->constant_value()) &&
(defn->constant_value().IsSmi() || defn->constant_value().IsOld()) &&
!defn->IsConstant() &&
!defn->IsPushArgument() &&
!defn->IsStoreIndexed() &&
!defn->IsStoreInstanceField() &&
!defn->IsStoreStaticField() &&
!defn->IsStoreVMField()) {
if (FLAG_trace_constant_propagation) {
OS::Print("Constant v%"Pd" = %s\n",
defn->ssa_temp_index(),
defn->constant_value().ToCString());
}
defn->ReplaceWith(new ConstantInstr(defn->constant_value()), &i);
}
}
// Replace branches where one target is unreachable with jumps.
BranchInstr* branch = block->last_instruction()->AsBranch();
if (branch != NULL) {
TargetEntryInstr* if_true = branch->true_successor();
TargetEntryInstr* if_false = branch->false_successor();
JoinEntryInstr* join = NULL;
Instruction* next = NULL;
if (!reachable_->Contains(if_true->preorder_number())) {
ASSERT(reachable_->Contains(if_false->preorder_number()));
ASSERT(if_false->parallel_move() == NULL);
ASSERT(if_false->loop_info() == NULL);
join = new JoinEntryInstr(if_false->block_id(), if_false->try_index());
next = if_false->next();
} else if (!reachable_->Contains(if_false->preorder_number())) {
ASSERT(if_true->parallel_move() == NULL);
ASSERT(if_true->loop_info() == NULL);
join = new JoinEntryInstr(if_true->block_id(), if_true->try_index());
next = if_true->next();
}
if (join != NULL) {
// Replace the branch with a jump to the reachable successor.
// Drop the comparison, which does not have side effects as long
// as it is a strict compare (the only one we can determine is
// constant with the current analysis).
GotoInstr* jump = new GotoInstr(join);
Instruction* previous = branch->previous();
branch->set_previous(NULL);
previous->LinkTo(jump);
// Replace the false target entry with the new join entry. We will
// recompute the dominators after this pass.
join->LinkTo(next);
branch->UnuseAllInputs();
}
}
}
graph_->DiscoverBlocks();
GrowableArray<BitVector*> dominance_frontier;
graph_->ComputeDominators(&dominance_frontier);
if (FLAG_trace_constant_propagation) {
OS::Print("\n==== After constant propagation ====\n");
FlowGraphPrinter printer(*graph_);
printer.PrintBlocks();
}
}
} // namespace dart
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