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dart / sdk.git / 116a6d386817afbfedfe2bc22c595731dd0703c1 / . / runtime / vm / flow_graph_optimizer.cc
blob: 2e5d624a3707ca3532b3cecea941d38992bcf5e4 [file] [log] [blame]
// Copyright (c) 2012, 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.");
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()) {
if (it.Current()->IsInstanceCall()) {
InstanceCallInstr* call = it.Current()->AsInstanceCall();
if (call->HasICData()) {
if (TryCreateICData(call)) {
VisitInstanceCall(call);
}
}
} else if (it.Current()->IsStrictCompare()) {
VisitStrictCompare(it.Current()->AsStrictCompare());
} else if (it.Current()->IsBranch()) {
ComparisonInstr* compare = it.Current()->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->ArgumentAt(i)->value()->ResultCid();
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 void ReplaceCurrentInstruction(ForwardInstructionIterator* it,
Instruction* current,
Instruction* replacement) {
if ((replacement != NULL) && current->IsDefinition()) {
Definition* current_defn = current->AsDefinition();
Definition* replacement_defn = replacement->AsDefinition();
ASSERT(replacement_defn != NULL);
current_defn->ReplaceUsesWith(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) {
ASSERT(!current->IsDefinition() ||
((current->AsDefinition()->input_use_list() == NULL) &&
(current->AsDefinition()->env_use_list() == NULL)));
if (current->IsDefinition()) {
OS::Print("Removing v%"Pd".\n",
current->AsDefinition()->ssa_temp_index());
} else {
OS::Print("Removing %s\n", current->DebugName());
}
}
it->RemoveCurrentFromGraph();
}
void FlowGraphOptimizer::OptimizeComputations() {
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();
if (replacement != current) {
// For non-definitions Canonicalize should return either NULL or
// this.
ASSERT((replacement == NULL) || current->IsDefinition());
ReplaceCurrentInstruction(&it, current, replacement);
}
}
}
}
void FlowGraphOptimizer::InsertConversion(Representation from,
Representation to,
Instruction* instr,
Value* use,
Definition* def,
Instruction* deopt_target) {
Definition* converted = NULL;
if ((from == kTagged) && (to == kUnboxedMint)) {
const intptr_t deopt_id = (deopt_target != NULL) ?
deopt_target->DeoptimizationTarget() : Isolate::kNoDeoptId;
ASSERT((deopt_target != NULL) || (def->GetPropagatedCid() == kDoubleCid));
converted = new UnboxIntegerInstr(new Value(def), deopt_id);
} else if ((from == kUnboxedMint) && (to == kTagged)) {
converted = new BoxIntegerInstr(new Value(def));
} else if (from == kUnboxedMint && to == kUnboxedDouble) {
// Convert by boxing/unboxing.
// TODO(fschneider): Implement direct unboxed mint-to-double conversion.
BoxIntegerInstr* boxed = new BoxIntegerInstr(new Value(def));
InsertBefore(instr, 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(new Value(def), NULL);
} else if ((from == kTagged) && (to == kUnboxedDouble)) {
const intptr_t deopt_id = (deopt_target != NULL) ?
deopt_target->DeoptimizationTarget() : Isolate::kNoDeoptId;
ASSERT((deopt_target != NULL) || (def->GetPropagatedCid() == kDoubleCid));
converted = new UnboxDoubleInstr(new Value(def), deopt_id);
}
ASSERT(converted != NULL);
InsertBefore(instr, converted, use->instruction()->env(),
Definition::kValue);
use->set_definition(converted);
}
void FlowGraphOptimizer::InsertConversionsFor(Definition* def) {
const Representation from_rep = def->representation();
for (Value* use = def->input_use_list();
use != NULL;
use = use->next_use()) {
const Representation to_rep =
use->instruction()->RequiredInputRepresentation(use->use_index());
if (from_rep == to_rep) {
continue;
}
Instruction* deopt_target = NULL;
Instruction* instr = use->instruction();
if (instr->IsPhi()) {
if (!instr->AsPhi()->is_alive()) continue;
// For phis conversions have to be inserted in the predecessor.
const BlockEntryInstr* pred =
instr->AsPhi()->block()->PredecessorAt(use->use_index());
instr = pred->last_instruction();
} else {
deopt_target = instr;
}
InsertConversion(from_rep, to_rep, instr, use, def, 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) continue;
if (join_entry->phis() != NULL) {
for (intptr_t i = 0; i < join_entry->phis()->length(); ++i) {
PhiInstr* phi = (*join_entry->phis())[i];
if (phi == NULL) continue;
if (phi->GetPropagatedCid() == 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) && (join_entry->phis() != NULL)) {
for (intptr_t i = 0; i < join_entry->phis()->length(); ++i) {
PhiInstr* phi = (*join_entry->phis())[i];
if ((phi != NULL) && (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 ICDataHasReceiverClassId(const ICData& ic_data, intptr_t class_id) {
ASSERT(ic_data.num_args_tested() > 0);
const intptr_t len = ic_data.NumberOfChecks();
for (intptr_t i = 0; i < len; i++) {
const intptr_t test_class_id = ic_data.GetReceiverClassIdAt(i);
if (test_class_id == class_id) {
return true;
}
}
return false;
}
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)
&& ICDataHasReceiverClassId(ic_data, kSmiCid);
}
static bool HasOnlySmiOrMint(const ICData& ic_data) {
if (ic_data.NumberOfChecks() == 1) {
return ICDataHasReceiverClassId(ic_data, kSmiCid)
|| ICDataHasReceiverClassId(ic_data, kMintCid);
}
return (ic_data.NumberOfChecks() == 2)
&& ICDataHasReceiverClassId(ic_data, kSmiCid)
&& ICDataHasReceiverClassId(ic_data, 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)
&& ICDataHasReceiverClassId(ic_data, 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);
}
static void RemovePushArguments(InstanceCallInstr* call) {
// Remove original push arguments.
for (intptr_t i = 0; i < call->ArgumentCount(); ++i) {
PushArgumentInstr* push = call->ArgumentAt(i);
push->ReplaceUsesWith(push->value()->definition());
push->RemoveFromGraph();
}
}
static void RemovePushArguments(StaticCallInstr* call) {
// Remove original push arguments.
for (intptr_t i = 0; i < call->ArgumentCount(); ++i) {
PushArgumentInstr* push = call->ArgumentAt(i);
push->ReplaceUsesWith(push->value()->definition());
push->RemoveFromGraph();
}
}
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::AddCheckClass(InstanceCallInstr* call,
Value* value) {
// Type propagation has not run yet, we cannot eliminate the check.
const ICData& unary_checks =
ICData::ZoneHandle(call->ic_data()->AsUnaryClassChecks());
Instruction* check = NULL;
if ((unary_checks.NumberOfChecks() == 1) &&
(unary_checks.GetReceiverClassIdAt(0) == kSmiCid)) {
check = new CheckSmiInstr(value, call->deopt_id());
} else {
check = new CheckClassInstr(value, call->deopt_id(), unary_checks);
}
InsertBefore(call, check, call->env(), Definition::kEffect);
}
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 idnex value
intptr_t FlowGraphOptimizer::PrepareIndexedOp(InstanceCallInstr* call,
intptr_t class_id,
Value** array,
Value** index) {
*array = call->ArgumentAt(0)->value();
*index = call->ArgumentAt(1)->value();
// Insert class check and index smi checks and attach a copy of the
// original environment because the operation can still deoptimize.
AddCheckClass(call, (*array)->Copy());
InsertBefore(call,
new CheckSmiInstr((*index)->Copy(), 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)->BindsToConstant() && (*index)->BindsToConstant()) {
ConstantInstr* array_def = (*array)->definition()->AsConstant();
const ImmutableArray& constant_array =
ImmutableArray::Cast(array_def->value());
ConstantInstr* index_def = (*index)->definition()->AsConstant();
if (index_def->value().IsSmi()) {
intptr_t constant_index = Smi::Cast(index_def->value()).Value();
skip_check = (constant_index < constant_array.Length());
}
}
if (!skip_check) {
// Insert array bounds check.
InsertBefore(call,
new CheckArrayBoundInstr((*array)->Copy(),
(*index)->Copy(),
class_id,
call),
call->env(),
Definition::kEffect);
}
if (class_id == kGrowableObjectArrayCid) {
// Insert data elements load.
LoadFieldInstr* elements =
new LoadFieldInstr((*array)->Copy(),
GrowableObjectArray::data_offset(),
Type::ZoneHandle(Type::DynamicType()));
elements->set_result_cid(kArrayCid);
InsertBefore(call, elements, NULL, Definition::kValue);
*array = new Value(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:
// Acceptable store index classes.
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;
}
if (FLAG_enable_type_checks) {
Value* array = call->ArgumentAt(0)->value();
Value* value = call->ArgumentAt(2)->value();
// 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));
Value* instantiator = NULL;
Value* type_args = NULL;
switch (class_id) {
case kArrayCid:
case kGrowableObjectArrayCid: {
const Class& instantiator_class = Class::Handle(target.Owner());
intptr_t type_arguments_instance_field_offset =
instantiator_class.type_arguments_instance_field_offset();
LoadFieldInstr* load_type_args =
new LoadFieldInstr(array->Copy(),
type_arguments_instance_field_offset,
Type::ZoneHandle()); // No type.
InsertBefore(call, load_type_args, NULL, Definition::kValue);
instantiator = array->Copy();
type_args = new Value(load_type_args);
break;
}
case kFloat32ArrayCid:
case kFloat64ArrayCid: {
ConstantInstr* null_constant = new ConstantInstr(Object::ZoneHandle());
InsertBefore(call, null_constant, NULL, Definition::kValue);
instantiator = new Value(null_constant);
type_args = new Value(null_constant);
ASSERT(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(),
value->Copy(),
instantiator,
type_args,
value_type,
String::ZoneHandle(Symbols::New("value")));
InsertBefore(call, assert_value, NULL, Definition::kValue);
}
Value* array = NULL;
Value* index = NULL;
intptr_t array_cid = PrepareIndexedOp(call, class_id, &array, &index);
Value* value = call->ArgumentAt(2)->value();
// Check if store barrier is needed.
bool needs_store_barrier = true;
if ((class_id == kFloat32ArrayCid) || (class_id == kFloat64ArrayCid)) {
ASSERT(!value_check.IsNull());
InsertBefore(call,
new CheckClassInstr(value->Copy(),
call->deopt_id(),
value_check),
call->env(),
Definition::kEffect);
needs_store_barrier = false;
} else if (ArgIsAlwaysSmi(*call->ic_data(), 2)) {
InsertBefore(call,
new CheckSmiInstr(value->Copy(), call->deopt_id()),
call->env(),
Definition::kEffect);
needs_store_barrier = false;
}
Definition* array_op =
new StoreIndexedInstr(array, index, value,
needs_store_barrier, array_cid, call->deopt_id());
call->ReplaceWith(array_op, current_iterator());
RemovePushArguments(call);
return true;
}
bool FlowGraphOptimizer::TryReplaceWithLoadIndexed(InstanceCallInstr* call) {
const intptr_t class_id = ReceiverClassId(call);
switch (class_id) {
case kArrayCid:
case kImmutableArrayCid:
case kGrowableObjectArrayCid:
case kFloat32ArrayCid:
case kFloat64ArrayCid:
case kUint8ArrayCid:
case kExternalUint8ArrayCid:
// Acceptable load index classes.
break;
default:
return false;
}
Value* array = NULL;
Value* index = NULL;
intptr_t array_cid = PrepareIndexedOp(call, class_id, &array, &index);
Definition* array_op = new LoadIndexedInstr(array, index, array_cid);
call->ReplaceWith(array_op, current_iterator());
RemovePushArguments(call);
return true;
}
void FlowGraphOptimizer::InsertBefore(Instruction* next,
Instruction* instr,
Environment* env,
Definition::UseKind use_kind) {
if (env != NULL) env->DeepCopyTo(instr);
if (use_kind == Definition::kValue) {
ASSERT(instr->IsDefinition());
instr->AsDefinition()->set_ssa_temp_index(
flow_graph_->alloc_ssa_temp_index());
}
instr->InsertBefore(next);
}
void FlowGraphOptimizer::InsertAfter(Instruction* prev,
Instruction* instr,
Environment* env,
Definition::UseKind use_kind) {
if (env != NULL) env->DeepCopyTo(instr);
if (use_kind == Definition::kValue) {
ASSERT(instr->IsDefinition());
instr->AsDefinition()->set_ssa_temp_index(
flow_graph_->alloc_ssa_temp_index());
}
instr->InsertAfter(prev);
}
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);
if (operands_type == kDoubleCid) {
Value* left = call->ArgumentAt(0)->value();
Value* right = call->ArgumentAt(1)->value();
// Check that either left or right are not a smi. Result or a
// binary operation with two smis is a smi not a double.
InsertBefore(call,
new CheckEitherNonSmiInstr(left->Copy(),
right->Copy(),
call),
call->env(),
Definition::kEffect);
BinaryDoubleOpInstr* double_bin_op =
new BinaryDoubleOpInstr(op_kind, left->Copy(), right->Copy(), call);
call->ReplaceWith(double_bin_op, current_iterator());
RemovePushArguments(call);
} else if (operands_type == kMintCid) {
if (!FlowGraphCompiler::SupportsUnboxedMints()) return false;
Value* left = call->ArgumentAt(0)->value();
Value* right = call->ArgumentAt(1)->value();
if ((op_kind == Token::kSHR) || (op_kind == Token::kSHL)) {
ShiftMintOpInstr* shift_op =
new ShiftMintOpInstr(op_kind, left, right, call);
call->ReplaceWith(shift_op, current_iterator());
} else {
BinaryMintOpInstr* bin_op =
new BinaryMintOpInstr(op_kind, left, right, call);
call->ReplaceWith(bin_op, current_iterator());
}
RemovePushArguments(call);
} else if (op_kind == Token::kMOD) {
// TODO(vegorov): implement fast path code for modulo.
ASSERT(operands_type == kSmiCid);
if (!call->ArgumentAt(1)->value()->BindsToConstant()) return false;
const Object& obj = call->ArgumentAt(1)->value()->BoundConstant();
if (!obj.IsSmi()) return false;
const intptr_t value = Smi::Cast(obj).Value();
if ((value > 0) && Utils::IsPowerOfTwo(value)) {
Value* left = call->ArgumentAt(0)->value();
// Insert smi check and attach a copy of the original
// environment because the smi operation can still deoptimize.
InsertBefore(call,
new CheckSmiInstr(left->Copy(), call->deopt_id()),
call->env(),
Definition::kEffect);
ConstantInstr* c = new ConstantInstr(Smi::Handle(Smi::New(value - 1)));
InsertBefore(call, c, NULL, Definition::kValue);
BinarySmiOpInstr* bin_op =
new BinarySmiOpInstr(Token::kBIT_AND, call, left, new Value(c));
call->ReplaceWith(bin_op, current_iterator());
RemovePushArguments(call);
} else {
// Did not replace.
return false;
}
} else {
ASSERT(operands_type == kSmiCid);
Value* left = call->ArgumentAt(0)->value();
Value* right = call->ArgumentAt(1)->value();
// Insert two smi checks and attach a copy of the original
// environment because the smi operation can still deoptimize.
InsertBefore(call,
new CheckSmiInstr(left->Copy(), call->deopt_id()),
call->env(),
Definition::kEffect);
InsertBefore(call,
new CheckSmiInstr(right->Copy(), call->deopt_id()),
call->env(),
Definition::kEffect);
BinarySmiOpInstr* bin_op = new BinarySmiOpInstr(op_kind, call, left, right);
call->ReplaceWith(bin_op, current_iterator());
RemovePushArguments(call);
}
return true;
}
bool FlowGraphOptimizer::TryReplaceWithUnaryOp(InstanceCallInstr* call,
Token::Kind op_kind) {
ASSERT(call->ArgumentCount() == 1);
Definition* unary_op = NULL;
if (HasOnlyOneSmi(*call->ic_data())) {
Value* value = call->ArgumentAt(0)->value();
InsertBefore(call,
new CheckSmiInstr(value->Copy(), call->deopt_id()),
call->env(),
Definition::kEffect);
unary_op = new UnarySmiOpInstr(op_kind, call, value);
} else if ((op_kind == Token::kBIT_NOT) &&
HasOnlySmiOrMint(*call->ic_data()) &&
FlowGraphCompiler::SupportsUnboxedMints()) {
Value* value = call->ArgumentAt(0)->value();
unary_op = new UnaryMintOpInstr(op_kind, value, call);
} else if (HasOnlyOneDouble(*call->ic_data()) &&
(op_kind == Token::kNEGATE)) {
Value* value = call->ArgumentAt(0)->value();
AddCheckClass(call, value->Copy());
ConstantInstr* minus_one =
new ConstantInstr(Double::ZoneHandle(Double::NewCanonical(-1)));
InsertBefore(call, minus_one, NULL, Definition::kValue);
unary_op = new BinaryDoubleOpInstr(Token::kMUL,
value,
new Value(minus_one),
call);
}
if (unary_op == NULL) return false;
call->ReplaceWith(unary_op, current_iterator());
RemovePushArguments(call);
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)->value()->definition();
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;
}
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)) {
AddCheckClass(call, call->ArgumentAt(0)->value()->Copy());
}
// Detach environment from the original instruction because it can't
// deoptimize.
call->set_env(NULL);
LoadFieldInstr* load = new LoadFieldInstr(
call->ArgumentAt(0)->value(),
field.Offset(),
AbstractType::ZoneHandle(field.type()));
call->ReplaceWith(load, current_iterator());
RemovePushArguments(call);
}
void FlowGraphOptimizer::InlineArrayLengthGetter(InstanceCallInstr* call,
intptr_t length_offset,
bool is_immutable,
MethodRecognizer::Kind kind) {
// Check receiver class.
AddCheckClass(call, call->ArgumentAt(0)->value()->Copy());
LoadFieldInstr* load = new LoadFieldInstr(
call->ArgumentAt(0)->value(),
length_offset,
Type::ZoneHandle(Type::SmiType()),
is_immutable);
load->set_result_cid(kSmiCid);
load->set_recognized_kind(kind);
call->ReplaceWith(load, current_iterator());
RemovePushArguments(call);
}
void FlowGraphOptimizer::InlineGArrayCapacityGetter(InstanceCallInstr* call) {
// Check receiver class.
AddCheckClass(call, call->ArgumentAt(0)->value()->Copy());
// TODO(srdjan): type of load should be GrowableObjectArrayType.
LoadFieldInstr* data_load = new LoadFieldInstr(
call->ArgumentAt(0)->value(),
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);
call->ReplaceWith(length_load, current_iterator());
RemovePushArguments(call);
}
static LoadFieldInstr* BuildLoadStringLength(Value* str) {
const bool is_immutable = true; // String length is immutable.
LoadFieldInstr* load = new LoadFieldInstr(
str,
String::length_offset(),
Type::ZoneHandle(Type::SmiType()),
is_immutable);
load->set_result_cid(kSmiCid);
return load;
}
void FlowGraphOptimizer::InlineStringLengthGetter(InstanceCallInstr* call) {
// Check receiver class.
AddCheckClass(call, call->ArgumentAt(0)->value()->Copy());
LoadFieldInstr* load = BuildLoadStringLength(call->ArgumentAt(0)->value());
call->ReplaceWith(load, current_iterator());
RemovePushArguments(call);
}
void FlowGraphOptimizer::InlineStringIsEmptyGetter(InstanceCallInstr* call) {
// Check receiver class.
AddCheckClass(call, call->ArgumentAt(0)->value()->Copy());
LoadFieldInstr* load = BuildLoadStringLength(call->ArgumentAt(0)->value());
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));
call->ReplaceWith(compare, current_iterator());
RemovePushArguments(call);
}
// 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;
}
// Not an implicit getter.
MethodRecognizer::Kind recognized_kind =
MethodRecognizer::RecognizeKind(target);
// VM objects length getter.
if ((recognized_kind == MethodRecognizer::kObjectArrayLength) ||
(recognized_kind == MethodRecognizer::kImmutableArrayLength) ||
(recognized_kind == MethodRecognizer::kGrowableArrayLength)) {
if (!ic_data.HasOneTarget()) {
// TODO(srdjan): Implement for mutiple targets.
return false;
}
switch (recognized_kind) {
case MethodRecognizer::kObjectArrayLength:
case MethodRecognizer::kImmutableArrayLength:
InlineArrayLengthGetter(call,
Array::length_offset(),
true,
recognized_kind);
break;
case MethodRecognizer::kGrowableArrayLength:
InlineArrayLengthGetter(call,
GrowableObjectArray::length_offset(),
false,
recognized_kind);
break;
default:
UNREACHABLE();
}
return true;
}
if (recognized_kind == MethodRecognizer::kGrowableArrayCapacity) {
InlineGArrayCapacityGetter(call);
return true;
}
if (recognized_kind == MethodRecognizer::kStringBaseLength) {
if (!ic_data.HasOneTarget()) {
// Target is not only StringBase_get_length.
return false;
}
InlineStringLengthGetter(call);
return true;
}
if (recognized_kind == MethodRecognizer::kStringBaseIsEmpty) {
if (!ic_data.HasOneTarget()) {
// Target is not only StringBase_get_isEmpty.
return false;
}
InlineStringIsEmptyGetter(call);
return true;
}
return false;
}
StringCharCodeAtInstr* FlowGraphOptimizer::BuildStringCharCodeAt(
InstanceCallInstr* call,
intptr_t cid) {
Value* str = call->ArgumentAt(0)->value();
Value* index = call->ArgumentAt(1)->value();
AddCheckClass(call, str->Copy());
InsertBefore(call,
new CheckSmiInstr(index->Copy(), 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->BindsToConstant() && index->BindsToConstant()) {
ConstantInstr* string_def = str->definition()->AsConstant();
const String& constant_string =
String::Cast(string_def->value());
ConstantInstr* index_def = index->definition()->AsConstant();
if (index_def->value().IsSmi()) {
intptr_t constant_index = Smi::Cast(index_def->value()).Value();
skip_check = (constant_index < constant_string.Length());
}
}
if (!skip_check) {
// Insert bounds check.
InsertBefore(call,
new CheckArrayBoundInstr(str->Copy(),
index->Copy(),
cid,
call),
call->env(),
Definition::kEffect);
}
return new StringCharCodeAtInstr(str, index, cid);
}
// 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);
if ((recognized_kind == MethodRecognizer::kStringBaseCharCodeAt) &&
(ic_data.NumberOfChecks() == 1) &&
((class_ids[0] == kOneByteStringCid) ||
(class_ids[0] == kTwoByteStringCid))) {
StringCharCodeAtInstr* instr = BuildStringCharCodeAt(call, class_ids[0]);
call->ReplaceWith(instr, current_iterator());
RemovePushArguments(call);
return true;
}
if ((recognized_kind == MethodRecognizer::kStringBaseCharAt) &&
(ic_data.NumberOfChecks() == 1) &&
(class_ids[0] == kOneByteStringCid)) {
// TODO(fschneider): Handle TwoByteString.
StringCharCodeAtInstr* load_char_code =
BuildStringCharCodeAt(call, class_ids[0]);
InsertBefore(call, load_char_code, NULL, Definition::kValue);
StringFromCharCodeInstr* char_at =
new StringFromCharCodeInstr(new Value(load_char_code));
call->ReplaceWith(char_at, current_iterator());
RemovePushArguments(call);
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 ((recognized_kind == MethodRecognizer::kDoubleToInteger) &&
(class_ids[0] == kDoubleCid)) {
AddCheckClass(call, call->ArgumentAt(0)->value()->Copy());
DoubleToIntegerInstr* d2int_instr =
new DoubleToIntegerInstr(call->ArgumentAt(0)->value(), call);
call->ReplaceWith(d2int_instr, current_iterator());
RemovePushArguments(call);
return true;
}
return false;
}
// 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)) {
// An instance call without ICData will trigger deoptimization.
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;
}
const Token::Kind op_kind = instr->token_kind();
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;
}
if (!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 (unary_checks.HasOneTarget()) {
// Type propagation has not run yet, we cannot eliminate the check.
AddCheckClass(instr, instr->ArgumentAt(0)->value()->Copy());
// 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(call->ArgumentAt(0)->value(), call);
call->ReplaceWith(sqrt, current_iterator());
RemovePushArguments(call);
}
}
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)) {
AddCheckClass(instr, instr->ArgumentAt(0)->value()->Copy());
}
bool needs_store_barrier = true;
if (ArgIsAlwaysSmi(*instr->ic_data(), 1)) {
InsertBefore(instr,
new CheckSmiInstr(instr->ArgumentAt(1)->value()->Copy(),
instr->deopt_id()),
instr->env(),
Definition::kEffect);
needs_store_barrier = false;
}
// Detach environment from the original instruction because it can't
// deoptimize.
instr->set_env(NULL);
StoreInstanceFieldInstr* store = new StoreInstanceFieldInstr(
field,
instr->ArgumentAt(0)->value(),
instr->ArgumentAt(1)->value(),
needs_store_barrier);
instr->ReplaceWith(store, current_iterator());
RemovePushArguments(instr);
return true;
}
// TODO(fschneider): Once we get rid of the distinction between Instruction
// and computation, this helper can go away.
static void HandleRelationalOp(FlowGraphOptimizer* optimizer,
RelationalOpInstr* comp,
Instruction* instr) {
if (!comp->HasICData() || (comp->ic_data()->NumberOfChecks() == 0)) {
return;
}
const ICData& ic_data = *comp->ic_data();
if (ic_data.NumberOfChecks() == 1) {
ASSERT(ic_data.HasOneTarget());
if (HasOnlyTwoSmis(ic_data)) {
optimizer->InsertBefore(
instr,
new CheckSmiInstr(comp->left()->Copy(), comp->deopt_id()),
instr->env(),
Definition::kEffect);
optimizer->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(this, instr, instr);
}
// TODO(fschneider): Once we get rid of the distinction between Instruction
// and computation, this helper can go away.
template <typename T>
static void HandleEqualityCompare(FlowGraphOptimizer* optimizer,
EqualityCompareInstr* comp,
T instr,
ForwardInstructionIterator* iterator) {
// 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(), comp->right());
instr->ReplaceWith(strict_comp, 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)) {
optimizer->InsertBefore(
instr,
new CheckSmiInstr(comp->left()->Copy(), comp->deopt_id()),
instr->env(),
Definition::kEffect);
optimizer->InsertBefore(
instr,
new CheckSmiInstr(comp->right()->Copy(), comp->deopt_id()),
instr->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());
const intptr_t deopt_id = comp->deopt_id();
if ((unary_checks_0.NumberOfChecks() == 1) &&
(unary_checks_0.GetReceiverClassIdAt(0) == kSmiCid)) {
// Smi only.
optimizer->InsertBefore(
instr,
new CheckSmiInstr(comp->left()->Copy(), deopt_id),
instr->env(),
Definition::kEffect);
} else {
// Smi or NULL.
optimizer->InsertBefore(
instr,
new CheckClassInstr(comp->left()->Copy(), deopt_id, unary_checks_0),
instr->env(),
Definition::kEffect);
}
const ICData& unary_checks_1 =
ICData::ZoneHandle(comp->ic_data()->AsUnaryClassChecksForArgNr(1));
if ((unary_checks_1.NumberOfChecks() == 1) &&
(unary_checks_1.GetReceiverClassIdAt(0) == kSmiCid)) {
// Smi only.
optimizer->InsertBefore(
instr,
new CheckSmiInstr(comp->right()->Copy(), deopt_id),
instr->env(),
Definition::kEffect);
} else {
// Smi or NULL.
optimizer->InsertBefore(
instr,
new CheckClassInstr(comp->right()->Copy(), deopt_id, unary_checks_1),
instr->env(),
Definition::kEffect);
}
comp->set_receiver_class_id(kSmiCid);
}
}
void FlowGraphOptimizer::VisitEqualityCompare(EqualityCompareInstr* instr) {
HandleEqualityCompare(this, instr, instr, current_iterator());
}
void FlowGraphOptimizer::VisitBranch(BranchInstr* instr) {
ComparisonInstr* comparison = instr->comparison();
if (comparison->IsRelationalOp()) {
HandleRelationalOp(this, comparison->AsRelationalOp(), instr);
} else if (comparison->IsEqualityCompare()) {
HandleEqualityCompare(this, comparison->AsEqualityCompare(), instr,
current_iterator());
} 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()->ResultCid()) ||
!MayBeBoxableNumber(instr->right()->ResultCid())) {
instr->set_needs_number_check(false);
}
}
// SminessPropagator ensures that CheckSmis are eliminated across phis.
class SminessPropagator : public ValueObject {
public:
explicit SminessPropagator(FlowGraph* flow_graph)
: flow_graph_(flow_graph),
known_smis_(new BitVector(flow_graph_->current_ssa_temp_index())),
rollback_checks_(10),
in_worklist_(NULL),
worklist_(0) { }
void Propagate();
private:
void PropagateSminessRecursive(BlockEntryInstr* block);
void AddToWorklist(PhiInstr* phi);
PhiInstr* RemoveLastFromWorklist();
void ProcessPhis();
FlowGraph* flow_graph_;
BitVector* known_smis_;
GrowableArray<intptr_t> rollback_checks_;
BitVector* in_worklist_;
GrowableArray<PhiInstr*> worklist_;
DISALLOW_COPY_AND_ASSIGN(SminessPropagator);
};
void SminessPropagator::AddToWorklist(PhiInstr* phi) {
if (in_worklist_ == NULL) {
in_worklist_ = new BitVector(flow_graph_->current_ssa_temp_index());
}
if (!in_worklist_->Contains(phi->ssa_temp_index())) {
in_worklist_->Add(phi->ssa_temp_index());
worklist_.Add(phi);
}
}
PhiInstr* SminessPropagator::RemoveLastFromWorklist() {
PhiInstr* phi = worklist_.RemoveLast();
ASSERT(in_worklist_->Contains(phi->ssa_temp_index()));
in_worklist_->Remove(phi->ssa_temp_index());
return phi;
}
static bool IsDefinitelySmiPhi(PhiInstr* phi) {
for (intptr_t i = 0; i < phi->InputCount(); i++) {
const intptr_t cid = phi->InputAt(i)->ResultCid();
if (cid != kSmiCid) {
return false;
}
}
return true;
}
static bool IsPossiblySmiPhi(PhiInstr* phi) {
for (intptr_t i = 0; i < phi->InputCount(); i++) {
const intptr_t cid = phi->InputAt(i)->ResultCid();
if ((cid != kSmiCid) && (cid != kDynamicCid)) {
return false;
}
}
return true;
}
void SminessPropagator::ProcessPhis() {
// First optimistically mark all possible smi-phis: phi is possibly a smi if
// its operands are either smis or phis in the worklist.
for (intptr_t i = 0; i < worklist_.length(); i++) {
PhiInstr* phi = worklist_[i];
ASSERT(phi->GetPropagatedCid() == kDynamicCid);
phi->SetPropagatedCid(kSmiCid);
// Append all phis that use this phi and can potentially be smi to the
// end of worklist.
for (Value* use = phi->input_use_list();
use != NULL;
use = use->next_use()) {
PhiInstr* phi_use = use->instruction()->AsPhi();
if ((phi_use != NULL) &&
(phi_use->GetPropagatedCid() == kDynamicCid) &&
IsPossiblySmiPhi(phi_use)) {
AddToWorklist(phi_use);
}
}
}
// Now unmark phis that are not definitely smi: that is have only
// smi operands.
while (!worklist_.is_empty()) {
PhiInstr* phi = RemoveLastFromWorklist();
if (!IsDefinitelySmiPhi(phi)) {
// Phi result is not a smi. Propagate this fact to phis that depend on it.
phi->SetPropagatedCid(kDynamicCid);
for (Value* use = phi->input_use_list();
use != NULL;
use = use->next_use()) {
PhiInstr* phi_use = use->instruction()->AsPhi();
if ((phi_use != NULL) && (phi_use->GetPropagatedCid() == kSmiCid)) {
AddToWorklist(phi_use);
}
}
}
}
}
void SminessPropagator::PropagateSminessRecursive(BlockEntryInstr* block) {
const intptr_t rollback_point = rollback_checks_.length();
for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
Instruction* instr = it.Current();
if (instr->IsCheckSmi()) {
const intptr_t value_ssa_index =
instr->InputAt(0)->definition()->ssa_temp_index();
if (!known_smis_->Contains(value_ssa_index)) {
known_smis_->Add(value_ssa_index);
rollback_checks_.Add(value_ssa_index);
}
}
}
for (intptr_t i = 0; i < block->dominated_blocks().length(); ++i) {
PropagateSminessRecursive(block->dominated_blocks()[i]);
}
if (block->last_instruction()->SuccessorCount() == 1 &&
block->last_instruction()->SuccessorAt(0)->IsJoinEntry()) {
JoinEntryInstr* join =
block->last_instruction()->SuccessorAt(0)->AsJoinEntry();
intptr_t pred_index = join->IndexOfPredecessor(block);
ASSERT(pred_index >= 0);
if (join->phis() != NULL) {
for (intptr_t i = 0; i < join->phis()->length(); ++i) {
PhiInstr* phi = (*join->phis())[i];
if (phi == NULL) continue;
Value* use = phi->InputAt(pred_index);
const intptr_t value_ssa_index = use->definition()->ssa_temp_index();
if (known_smis_->Contains(value_ssa_index) &&
(phi->GetPropagatedCid() != kSmiCid)) {
use->set_reaching_cid(kSmiCid);
AddToWorklist(phi);
}
}
}
}
for (intptr_t i = rollback_point; i < rollback_checks_.length(); i++) {
known_smis_->Remove(rollback_checks_[i]);
}
rollback_checks_.TruncateTo(rollback_point);
}
void SminessPropagator::Propagate() {
PropagateSminessRecursive(flow_graph_->graph_entry());
ProcessPhis();
}
void FlowGraphOptimizer::PropagateSminess() {
SminessPropagator propagator(flow_graph_);
propagator.Propagate();
}
// 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);
Definition* LoadArrayLength(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_;
class ArrayLengthData : public ValueObject {
public:
ArrayLengthData(Definition* array, Definition* array_length)
: array_(array), array_length_(array_length) { }
Definition* array() const { return array_; }
Definition* array_length() const { return array_length_; }
typedef Definition* Value;
typedef Definition* Key;
typedef class ArrayLengthData Pair;
// KeyValueTrait members.
static Key KeyOf(const ArrayLengthData& data) {
return data.array();
}
static Value ValueOf(const ArrayLengthData& data) {
return data.array_length();
}
static inline intptr_t Hashcode(Key key) {
return reinterpret_cast<intptr_t>(key);
}
static inline bool IsKeyEqual(const ArrayLengthData& kv, Key key) {
return kv.array() == key;
}
private:
Definition* array_;
Definition* array_length_;
};
DirectChainedHashMap<ArrayLengthData> array_lengths_;
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->GetPropagatedCid() == 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->GetPropagatedCid() == 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) {
Value* next_use = NULL;
Value* prev_use = NULL;
for (Value* use = def->input_use_list();
use != NULL;
use = next_use) {
next_use = use->next_use();
// Skip dead phis.
if (use->instruction()->IsPhi() &&
!use->instruction()->AsPhi()->is_alive()) {
prev_use = use;
continue;
}
if (IsDominatedUse(dom, use)) {
if (prev_use != NULL) {
prev_use->set_next_use(next_use);
} else {
def->set_input_use_list(next_use);
}
use->set_definition(other);
use->AddToInputUseList();
} else {
prev_use = use;
}
}
}
// 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);
constraint->InsertAfter(after);
constraint->set_ssa_temp_index(flow_graph_->alloc_ssa_temp_index());
RenameDominatedUses(defn, after, constraint);
constraints_.Add(constraint);
constraint->value()->set_instruction(constraint);
constraint->value()->set_use_index(0);
constraint->value()->AddToInputUseList();
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());
}
}
}
Definition* RangeAnalysis::LoadArrayLength(CheckArrayBoundInstr* check) {
Definition* array = check->array()->definition();
Definition* length = array_lengths_.Lookup(array);
if (length != NULL) return length;
StaticCallInstr* allocation = array->AsStaticCall();
if ((allocation != NULL) &&
allocation->is_known_constructor() &&
(allocation->ResultCid() == kArrayCid)) {
// For fixed length arrays check if array is the result of a constructor
// call. In this case we can use the length passed to the constructor
// instead of loading it from array itself.
length = allocation->ArgumentAt(1)->value()->definition();
} else {
// Load length from the array. Do not insert instruction into the graph.
// It will only be used in range boundaries.
LoadFieldInstr* length_load = new LoadFieldInstr(
check->array()->Copy(),
Array::length_offset(),
Type::ZoneHandle(Type::SmiType()),
true); // Immutable.
length_load->set_recognized_kind(MethodRecognizer::kObjectArrayLength);
length_load->set_result_cid(kSmiCid);
length_load->set_ssa_temp_index(flow_graph_->alloc_ssa_temp_index());
length = length_load;
}
ASSERT(length != NULL);
array_lengths_.Insert(ArrayLengthData(array, length));
return length;
}
void RangeAnalysis::ConstrainValueAfterCheckArrayBound(
Definition* defn, CheckArrayBoundInstr* check) {
if ((check->array_type() != kArrayCid) &&
(check->array_type() != kImmutableArrayCid)) {
return;
}
Definition* length = LoadArrayLength(check);
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(LoadArrayLength(check));
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]->RemoveDependency();
constraints_[i]->RemoveFromGraph();
}
}
void FlowGraphOptimizer::InferSmiRanges() {
RangeAnalysis range_analysis(flow_graph_);
range_analysis.Analyze();
}
void FlowGraphTypePropagator::VisitBlocks() {
ASSERT(current_iterator_ == NULL);
for (intptr_t i = 0; i < block_order_.length(); ++i) {
BlockEntryInstr* entry = block_order_[i];
entry->Accept(this);
ForwardInstructionIterator it(entry);
current_iterator_ = &it;
for (; !it.Done(); it.Advance()) {
Instruction* current = it.Current();
// No need to propagate the input types of the instruction, as long as
// PhiInstr's are handled as part of JoinEntryInstr.
// Visit the instruction and possibly eliminate type checks.
current->Accept(this);
// The instruction may have been removed from the graph.
Definition* defn = current->AsDefinition();
if ((defn != NULL) &&
!defn->IsPushArgument() &&
(defn->previous() != NULL)) {
// Cache the propagated computation type.
AbstractType& type = AbstractType::Handle(defn->CompileType());
still_changing_ = defn->SetPropagatedType(type) || still_changing_;
// Propagate class ids.
const intptr_t cid = defn->ResultCid();
still_changing_ = defn->SetPropagatedCid(cid) || still_changing_;
}
}
current_iterator_ = NULL;
}
}
void FlowGraphTypePropagator::VisitAssertAssignable(
AssertAssignableInstr* instr) {
bool is_null, is_instance;
if (FLAG_eliminate_type_checks &&
!instr->is_eliminated() &&
((instr->value()->CanComputeIsNull(&is_null) && is_null) ||
(instr->value()->CanComputeIsInstanceOf(instr->dst_type(), &is_instance)
&& is_instance))) {
// TODO(regis): Remove is_eliminated_ field and support.
instr->eliminate();
Value* use = instr->value();
ASSERT(use != NULL);
Definition* result = use->definition();
ASSERT(result != NULL);
// Replace uses and remove the current instruction via the iterator.
instr->ReplaceUsesWith(result);
ASSERT(current_iterator()->Current() == instr);
current_iterator()->RemoveCurrentFromGraph();
if (FLAG_trace_optimization) {
OS::Print("Replacing v%"Pd" with v%"Pd"\n",
instr->ssa_temp_index(),
result->ssa_temp_index());
}
if (FLAG_trace_type_check_elimination) {
FlowGraphPrinter::PrintTypeCheck(parsed_function(),
instr->token_pos(),
instr->value(),
instr->dst_type(),
instr->dst_name(),
instr->is_eliminated());
}
}
}
void FlowGraphTypePropagator::VisitAssertBoolean(AssertBooleanInstr* instr) {
bool is_null, is_bool;
if (FLAG_eliminate_type_checks &&
!instr->is_eliminated() &&
instr->value()->CanComputeIsNull(&is_null) &&
!is_null &&
instr->value()->CanComputeIsInstanceOf(Type::Handle(Type::BoolType()),
&is_bool) &&
is_bool) {
// TODO(regis): Remove is_eliminated_ field and support.
instr->eliminate();
Value* use = instr->value();
Definition* result = use->definition();
ASSERT(result != NULL);
// Replace uses and remove the current instruction via the iterator.
instr->ReplaceUsesWith(result);
ASSERT(current_iterator()->Current() == instr);
current_iterator()->RemoveCurrentFromGraph();
if (FLAG_trace_optimization) {
OS::Print("Replacing v%"Pd" with v%"Pd"\n",
instr->ssa_temp_index(),
result->ssa_temp_index());
}
if (FLAG_trace_type_check_elimination) {
const String& name = String::Handle(Symbols::New("boolean expression"));
FlowGraphPrinter::PrintTypeCheck(parsed_function(),
instr->token_pos(),
instr->value(),
Type::Handle(Type::BoolType()),
name,
instr->is_eliminated());
}
}
}
void FlowGraphTypePropagator::VisitInstanceOf(InstanceOfInstr* instr) {
bool is_null;
bool is_instance = false;
if (FLAG_eliminate_type_checks &&
instr->value()->CanComputeIsNull(&is_null) &&
(is_null ||
instr->value()->CanComputeIsInstanceOf(instr->type(), &is_instance))) {
Definition* result = new ConstantInstr(Bool::ZoneHandle(Bool::Get(
instr->negate_result() ? !is_instance : is_instance)));
result->set_ssa_temp_index(flow_graph_->alloc_ssa_temp_index());
result->InsertBefore(instr);
// Replace uses and remove the current instruction via the iterator.
instr->ReplaceUsesWith(result);
ASSERT(current_iterator()->Current() == instr);
current_iterator()->RemoveCurrentFromGraph();
if (FLAG_trace_optimization) {
OS::Print("Replacing v%"Pd" with v%"Pd"\n",
instr->ssa_temp_index(),
result->ssa_temp_index());
}
if (FLAG_trace_type_check_elimination) {
const String& name = String::Handle(Symbols::New("InstanceOf"));
FlowGraphPrinter::PrintTypeCheck(parsed_function(),
instr->token_pos(),
instr->value(),
instr->type(),
name,
/* eliminated = */ true);
}
}
}
void FlowGraphTypePropagator::VisitGraphEntry(GraphEntryInstr* graph_entry) {
// Visit incoming parameters.
for (intptr_t i = 0; i < graph_entry->initial_definitions()->length(); i++) {
ParameterInstr* param =
(*graph_entry->initial_definitions())[i]->AsParameter();
if (param != NULL) VisitParameter(param);
}
}
void FlowGraphTypePropagator::VisitJoinEntry(JoinEntryInstr* join_entry) {
if (join_entry->phis() != NULL) {
for (intptr_t i = 0; i < join_entry->phis()->length(); ++i) {
PhiInstr* phi = (*join_entry->phis())[i];
if (phi != NULL) {
VisitPhi(phi);
}
}
}
}
// TODO(srdjan): Investigate if the propagated cid should be more specific.
void FlowGraphTypePropagator::VisitPushArgument(PushArgumentInstr* push) {
if (!push->has_propagated_cid()) push->SetPropagatedCid(kDynamicCid);
}
void FlowGraphTypePropagator::VisitPhi(PhiInstr* phi) {
// We could set the propagated type of the phi to the least upper bound of its
// input propagated types. However, keeping all propagated types allows us to
// optimize method dispatch.
// TODO(regis): Support a set of propagated types. For now, we compute the
// least specific of the input propagated types.
AbstractType& type = AbstractType::Handle(phi->LeastSpecificInputType());
bool changed = phi->SetPropagatedType(type);
if (changed) {
still_changing_ = true;
}
// Merge class ids: if any two inputs have different class ids then result
// is kDynamicCid.
intptr_t merged_cid = kIllegalCid;
for (intptr_t i = 0; i < phi->InputCount(); i++) {
// Result cid of UseVal can be kIllegalCid if the referred definition
// has not been visited yet.
intptr_t cid = phi->InputAt(i)->ResultCid();
if (cid == kIllegalCid) {
still_changing_ = true;
continue;
}
if (merged_cid == kIllegalCid) {
// First time set.
merged_cid = cid;
} else if (merged_cid != cid) {
merged_cid = kDynamicCid;
}
}
if (merged_cid == kIllegalCid) {
merged_cid = kDynamicCid;
}
changed = phi->SetPropagatedCid(merged_cid);
if (changed) {
still_changing_ = true;
}
}
void FlowGraphTypePropagator::VisitParameter(ParameterInstr* param) {
// TODO(regis): Once we inline functions, the propagated type of the formal
// parameter will reflect the compile type of the passed-in argument.
// For now, we do not know anything about the argument type and therefore set
// it to the DynamicType, unless the argument is a compiler generated value,
// i.e. the receiver argument or the constructor phase argument.
AbstractType& param_type = AbstractType::Handle(Type::DynamicType());
param->SetPropagatedCid(kDynamicCid);
bool param_type_is_known = false;
if (param->index() == 0) {
const Function& function = parsed_function().function();
if ((function.IsDynamicFunction() || function.IsConstructor())) {
// Parameter is the receiver .
param_type_is_known = true;
}
} else if ((param->index() == 1) &&
parsed_function().function().IsConstructor()) {
// Parameter is the constructor phase.
param_type_is_known = true;
}
if (param_type_is_known) {
LocalScope* scope = parsed_function().node_sequence()->scope();
param_type = scope->VariableAt(param->index())->type().raw();
if (FLAG_use_cha) {
const intptr_t cid = Class::Handle(param_type.type_class()).id();
if (!CHA::HasSubclasses(cid)) {
// Receiver's class has no subclasses.
param->SetPropagatedCid(cid);
}
}
}
bool changed = param->SetPropagatedType(param_type);
if (changed) {
still_changing_ = true;
}
}
void FlowGraphTypePropagator::PropagateTypes() {
// TODO(regis): Is there a way to make this more efficient, e.g. by visiting
// only blocks depending on blocks that have changed and not the whole graph.
do {
still_changing_ = false;
VisitBlocks();
} while (still_changing_);
}
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;
}
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.
it->RemoveCurrentFromGraph();
GotoInstr* last = pre_header->last_instruction()->AsGoto();
current->InsertBefore(last);
// Attach the environment of the Goto instruction to the hoisted
// instruction and set the correct deopt_id.
ASSERT(last->env() != NULL);
last->env()->DeepCopyTo(current);
current->deopt_id_ = last->GetDeoptId();
}
void LICM::TryHoistCheckSmiThroughPhi(ForwardInstructionIterator* it,
BlockEntryInstr* header,
BlockEntryInstr* pre_header,
CheckSmiInstr* current) {
PhiInstr* phi = current->InputAt(0)->definition()->AsPhi();
if (!header->loop_info()->Contains(phi->block()->preorder_number())) {
return;
}
if (phi->GetPropagatedCid() == 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->ResultCid() != kSmiCid) {
if ((non_smi_input != kNotFound) || (input->ResultCid() != 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. Maintain use lists.
Definition* non_smi_input_defn = phi->InputAt(non_smi_input)->definition();
current->value()->RemoveFromInputUseList();
current->value()->set_definition(non_smi_input_defn);
current->value()->AddToInputUseList();
phi->SetPropagatedCid(kSmiCid);
}
void LICM::Optimize(FlowGraph* flow_graph) {
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 NumberLoadExpressions(FlowGraph* graph) {
DirectChainedHashMap<PointerKeyValueTrait<Definition> > map;
intptr_t expr_id = 0;
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++);
} else {
defn->set_expr_id(result->expr_id());
}
}
}
return expr_id;
}
static void ComputeAvailableLoads(
FlowGraph* graph,
intptr_t max_expr_id,
const GrowableArray<BitVector*>& avail_in) {
// Initialize gen-, kill-, out-sets.
intptr_t num_blocks = graph->preorder().length();
GrowableArray<BitVector*> avail_out(num_blocks);
GrowableArray<BitVector*> avail_gen(num_blocks);
GrowableArray<BitVector*> avail_kill(num_blocks);
for (intptr_t i = 0; i < num_blocks; i++) {
avail_out.Add(new BitVector(max_expr_id));
avail_gen.Add(new BitVector(max_expr_id));
avail_kill.Add(new BitVector(max_expr_id));
}
for (BlockIterator block_it = graph->reverse_postorder_iterator();
!block_it.Done();
block_it.Advance()) {
BlockEntryInstr* block = block_it.Current();
intptr_t preorder_number = block->preorder_number();
for (BackwardInstructionIterator instr_it(block);
!instr_it.Done();
instr_it.Advance()) {
Instruction* instr = instr_it.Current();
if (instr->HasSideEffect()) {
avail_kill[preorder_number]->SetAll();
break;
}
Definition* defn = instr_it.Current()->AsDefinition();
if ((defn == NULL) || !IsLoadEliminationCandidate(defn)) {
continue;
}
avail_gen[preorder_number]->Add(defn->expr_id());
}
avail_out[preorder_number]->CopyFrom(avail_gen[preorder_number]);
}
BitVector* temp = new BitVector(avail_in[0]->length());
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();
BitVector* block_in = avail_in[block->preorder_number()];
BitVector* block_out = avail_out[block->preorder_number()];
BitVector* block_kill = avail_kill[block->preorder_number()];
BitVector* block_gen = avail_gen[block->preorder_number()];
if (FLAG_trace_optimization) {
OS::Print("B%"Pd"", block->block_id());
block_in->Print();
block_out->Print();
OS::Print("\n");
}
// 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 {
temp->SetAll();
ASSERT(block->PredecessorCount() > 0);
for (intptr_t i = 0; i < block->PredecessorCount(); i++) {
BlockEntryInstr* pred = block->PredecessorAt(i);
BitVector* pred_out = avail_out[pred->preorder_number()];
temp->Intersect(*pred_out);
}
}
if (!temp->Equals(*block_in)) {
block_in->CopyFrom(temp);
if (block_out->KillAndAdd(block_kill, block_gen)) changed = true;
}
}
}
}
static bool OptimizeLoads(
BlockEntryInstr* block,
GrowableArray<Definition*>* definitions,
const GrowableArray<BitVector*>& avail_in) {
// TODO(fschneider): Factor out code shared with the existing CSE pass.
// Delete loads that are killed (not available) at the entry.
intptr_t pre_num = block->preorder_number();
ASSERT(avail_in[pre_num]->length() == definitions->length());
for (intptr_t i = 0; i < avail_in[pre_num]->length(); i++) {
if (!avail_in[pre_num]->Contains(i)) {
(*definitions)[i] = NULL;
}
}
bool changed = false;
for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
Instruction* instr = it.Current();
if (instr->HasSideEffect()) {
// Handle local side effects by clearing current definitions.
for (intptr_t i = 0; i < definitions->length(); i++) {
(*definitions)[i] = NULL;
}
continue;
}
Definition* defn = instr->AsDefinition();
if ((defn == NULL) || !IsLoadEliminationCandidate(defn)) {
continue;
}
Definition* result = (*definitions)[defn->expr_id()];
if (result == NULL) {
(*definitions)[defn->expr_id()] = defn;
continue;
}
// Replace current with lookup result.
defn->ReplaceUsesWith(result);
it.RemoveCurrentFromGraph();
changed = true;
if (FLAG_trace_optimization) {
OS::Print("Replacing load v%"Pd" with v%"Pd"\n",
defn->ssa_temp_index(),
result->ssa_temp_index());
}
}
// 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) {
GrowableArray<Definition*> child_defs(definitions->length());
child_defs.AddArray(*definitions);
changed = OptimizeLoads(child, &child_defs, avail_in) || changed;
} else {
changed = OptimizeLoads(child, definitions, avail_in) || changed;
}
}
return changed;
}
bool DominatorBasedCSE::Optimize(FlowGraph* graph) {
bool changed = false;
if (FLAG_load_cse) {
intptr_t max_expr_id = NumberLoadExpressions(graph);
if (max_expr_id > 0) {
intptr_t num_blocks = graph->preorder().length();
GrowableArray<BitVector*> avail_in(num_blocks);
for (intptr_t i = 0; i < num_blocks; i++) {
avail_in.Add(new BitVector(max_expr_id));
}
ComputeAvailableLoads(graph, max_expr_id, avail_in);
GrowableArray<Definition*> definitions(max_expr_id);
for (intptr_t j = 0; j < max_expr_id ; j++) {
definitions.Add(NULL);
}
changed = OptimizeLoads(graph->graph_entry(), &definitions, avail_in);
}
}
DirectChainedHashMap<PointerKeyValueTrait<Instruction> > map;
changed = OptimizeRecursive(graph->graph_entry(), &map) || changed;
return changed;
}
bool DominatorBasedCSE::OptimizeRecursive(
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);
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(child, &child_map) || changed;
} else {
// Reuse map for the last child.
changed = OptimizeRecursive(child, map) || changed;
}
}
return changed;
}
ConstantPropagator::ConstantPropagator(
FlowGraph* graph,
const GrowableArray<BlockEntryInstr*>& ignored)
: FlowGraphVisitor(ignored),
graph_(graph),
unknown_(Object::ZoneHandle(Object::transition_sentinel())),
non_constant_(Object::ZoneHandle(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) {
ZoneGrowableArray<PhiInstr*>* phis = block->phis();
if (phis != NULL) {
for (intptr_t phi_idx = 0; phi_idx < phis->length(); ++phi_idx) {
PhiInstr* phi = (*phis)[phi_idx];
if (phi == NULL) continue;
phi->Accept(this);
}
}
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());
}
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()) {
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()->ResultCid() != kDynamicCid)) ||
(right.IsNull() && (instr->left()->ResultCid() != kDynamicCid))) {
bool result = left.IsNull() ? (instr->right()->ResultCid() == kNullCid)
: (instr->left()->ResultCid() == kNullCid);
if (instr->kind() == Token::kNE_STRICT) result = !result;
SetValue(instr, Bool::ZoneHandle(Bool::Get(result)));
} 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, Bool::ZoneHandle(Bool::Get(result)));
}
}
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)) {
// TODO(kmillikin): Handle equality comparison of constants.
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)) {
// TODO(kmillikin): Handle relational comparison of constants.
SetValue(instr, non_constant_);
}
}
void ConstantPropagator::VisitNativeCall(NativeCallInstr* instr) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitStringCharCodeAt(StringCharCodeAtInstr* 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)) {
SetValue(instr, Bool::ZoneHandle(Bool::Get(value.raw() != Bool::True())));
}
}
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) {
SetValue(instr, non_constant_);
}
void ConstantPropagator::VisitStoreVMField(StoreVMFieldInstr* instr) {
SetValue(instr, instr->value()->definition()->constant_value());
}
void ConstantPropagator::VisitInstantiateTypeArguments(
InstantiateTypeArgumentsInstr* instr) {
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::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();
if (!reachable_->Contains(block->preorder_number())) {
if (FLAG_trace_constant_propagation) {
OS::Print("Unreachable B%"Pd"\n", block->block_id());
}
continue;
}
JoinEntryInstr* join = block->AsJoinEntry();
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) {
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 (intptr_t phi_idx = 0; phi_idx < phis->length(); ++phi_idx) {
PhiInstr* phi = (*phis)[phi_idx];
if (phi == NULL) continue;
phi->inputs_[live_count] = phi->inputs_[pred_idx];
}
}
++live_count;
}
}
if (live_count < pred_count) {
for (intptr_t phi_idx = 0; phi_idx < phis->length(); ++phi_idx) {
PhiInstr* phi = (*phis)[phi_idx];
if (phi == NULL) continue;
phi->inputs_.TruncateTo(live_count);
if (live_count == 1) redundant_phis.Add(phi);
}
}
}
}
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.
//
// TODO(kmillikin): Extend this to handle booleans, other number
// types, etc.
if ((defn != NULL) &&
defn->constant_value().IsSmi() &&
!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());
}
i.ReplaceCurrentWith(new ConstantInstr(defn->constant_value()));
}
}
// 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(branch->comparison()->IsStrictCompare());
ASSERT(if_false->parallel_move() == NULL);
ASSERT(if_false->loop_info() == NULL);
join = new JoinEntryInstr(if_false->block_id(),
if_false->try_index(),
if_false->loop_depth());
next = if_false->next();
} else if (!reachable_->Contains(if_false->preorder_number())) {
ASSERT(branch->comparison()->IsStrictCompare());
ASSERT(if_true->parallel_move() == NULL);
ASSERT(if_true->loop_info() == NULL);
join = new JoinEntryInstr(if_true->block_id(),
if_true->try_index(),
if_true->loop_depth());
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);
}
}
}
graph_->DiscoverBlocks();
GrowableArray<BitVector*> dominance_frontier;
graph_->ComputeDominators(&dominance_frontier);
graph_->ComputeUseLists();
if (FLAG_remove_redundant_phis) {
for (intptr_t i = 0; i < redundant_phis.length(); i++) {
PhiInstr* phi = redundant_phis[i];
phi->ReplaceUsesWith(phi->InputAt(0)->definition());
phi->mark_dead();
}
}
if (FLAG_trace_constant_propagation) {
OS::Print("\n==== After constant propagation ====\n");
FlowGraphPrinter printer(*graph_);
printer.PrintBlocks();
}
}
} // namespace dart