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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "instruction_simplifier.h"
#include "intrinsics.h"
#include "mirror/class-inl.h"
#include "scoped_thread_state_change.h"
namespace art {
class InstructionSimplifierVisitor : public HGraphDelegateVisitor {
public:
InstructionSimplifierVisitor(HGraph* graph, OptimizingCompilerStats* stats)
: HGraphDelegateVisitor(graph),
stats_(stats) {}
void Run();
private:
void RecordSimplification() {
simplification_occurred_ = true;
simplifications_at_current_position_++;
if (stats_) {
stats_->RecordStat(kInstructionSimplifications);
}
}
bool ReplaceRotateWithRor(HBinaryOperation* op, HUShr* ushr, HShl* shl);
bool TryReplaceWithRotate(HBinaryOperation* instruction);
bool TryReplaceWithRotateConstantPattern(HBinaryOperation* op, HUShr* ushr, HShl* shl);
bool TryReplaceWithRotateRegisterNegPattern(HBinaryOperation* op, HUShr* ushr, HShl* shl);
bool TryReplaceWithRotateRegisterSubPattern(HBinaryOperation* op, HUShr* ushr, HShl* shl);
bool TryMoveNegOnInputsAfterBinop(HBinaryOperation* binop);
void VisitShift(HBinaryOperation* shift);
void VisitSuspendCheck(HSuspendCheck* check) OVERRIDE;
void VisitEqual(HEqual* equal) OVERRIDE;
void VisitNotEqual(HNotEqual* equal) OVERRIDE;
void VisitBooleanNot(HBooleanNot* bool_not) OVERRIDE;
void VisitInstanceFieldSet(HInstanceFieldSet* equal) OVERRIDE;
void VisitStaticFieldSet(HStaticFieldSet* equal) OVERRIDE;
void VisitArraySet(HArraySet* equal) OVERRIDE;
void VisitTypeConversion(HTypeConversion* instruction) OVERRIDE;
void VisitNullCheck(HNullCheck* instruction) OVERRIDE;
void VisitArrayLength(HArrayLength* instruction) OVERRIDE;
void VisitCheckCast(HCheckCast* instruction) OVERRIDE;
void VisitAdd(HAdd* instruction) OVERRIDE;
void VisitAnd(HAnd* instruction) OVERRIDE;
void VisitCondition(HCondition* instruction) OVERRIDE;
void VisitGreaterThan(HGreaterThan* condition) OVERRIDE;
void VisitGreaterThanOrEqual(HGreaterThanOrEqual* condition) OVERRIDE;
void VisitLessThan(HLessThan* condition) OVERRIDE;
void VisitLessThanOrEqual(HLessThanOrEqual* condition) OVERRIDE;
void VisitBelow(HBelow* condition) OVERRIDE;
void VisitBelowOrEqual(HBelowOrEqual* condition) OVERRIDE;
void VisitAbove(HAbove* condition) OVERRIDE;
void VisitAboveOrEqual(HAboveOrEqual* condition) OVERRIDE;
void VisitDiv(HDiv* instruction) OVERRIDE;
void VisitMul(HMul* instruction) OVERRIDE;
void VisitNeg(HNeg* instruction) OVERRIDE;
void VisitNot(HNot* instruction) OVERRIDE;
void VisitOr(HOr* instruction) OVERRIDE;
void VisitShl(HShl* instruction) OVERRIDE;
void VisitShr(HShr* instruction) OVERRIDE;
void VisitSub(HSub* instruction) OVERRIDE;
void VisitUShr(HUShr* instruction) OVERRIDE;
void VisitXor(HXor* instruction) OVERRIDE;
void VisitInstanceOf(HInstanceOf* instruction) OVERRIDE;
void VisitFakeString(HFakeString* fake_string) OVERRIDE;
void VisitInvoke(HInvoke* invoke) OVERRIDE;
void VisitDeoptimize(HDeoptimize* deoptimize) OVERRIDE;
bool CanEnsureNotNullAt(HInstruction* instr, HInstruction* at) const;
void SimplifyRotate(HInvoke* invoke, bool is_left);
void SimplifySystemArrayCopy(HInvoke* invoke);
void SimplifyStringEquals(HInvoke* invoke);
OptimizingCompilerStats* stats_;
bool simplification_occurred_ = false;
int simplifications_at_current_position_ = 0;
// We ensure we do not loop infinitely. The value is a finger in the air guess
// that should allow enough simplification.
static constexpr int kMaxSamePositionSimplifications = 10;
};
void InstructionSimplifier::Run() {
InstructionSimplifierVisitor visitor(graph_, stats_);
visitor.Run();
}
void InstructionSimplifierVisitor::Run() {
// Iterate in reverse post order to open up more simplifications to users
// of instructions that got simplified.
for (HReversePostOrderIterator it(*GetGraph()); !it.Done();) {
// The simplification of an instruction to another instruction may yield
// possibilities for other simplifications. So although we perform a reverse
// post order visit, we sometimes need to revisit an instruction index.
simplification_occurred_ = false;
VisitBasicBlock(it.Current());
if (simplification_occurred_ &&
(simplifications_at_current_position_ < kMaxSamePositionSimplifications)) {
// New simplifications may be applicable to the instruction at the
// current index, so don't advance the iterator.
continue;
}
simplifications_at_current_position_ = 0;
it.Advance();
}
}
namespace {
bool AreAllBitsSet(HConstant* constant) {
return Int64FromConstant(constant) == -1;
}
} // namespace
// Returns true if the code was simplified to use only one negation operation
// after the binary operation instead of one on each of the inputs.
bool InstructionSimplifierVisitor::TryMoveNegOnInputsAfterBinop(HBinaryOperation* binop) {
DCHECK(binop->IsAdd() || binop->IsSub());
DCHECK(binop->GetLeft()->IsNeg() && binop->GetRight()->IsNeg());
HNeg* left_neg = binop->GetLeft()->AsNeg();
HNeg* right_neg = binop->GetRight()->AsNeg();
if (!left_neg->HasOnlyOneNonEnvironmentUse() ||
!right_neg->HasOnlyOneNonEnvironmentUse()) {
return false;
}
// Replace code looking like
// NEG tmp1, a
// NEG tmp2, b
// ADD dst, tmp1, tmp2
// with
// ADD tmp, a, b
// NEG dst, tmp
// Note that we cannot optimize `(-a) + (-b)` to `-(a + b)` for floating-point.
// When `a` is `-0.0` and `b` is `0.0`, the former expression yields `0.0`,
// while the later yields `-0.0`.
if (!Primitive::IsIntegralType(binop->GetType())) {
return false;
}
binop->ReplaceInput(left_neg->GetInput(), 0);
binop->ReplaceInput(right_neg->GetInput(), 1);
left_neg->GetBlock()->RemoveInstruction(left_neg);
right_neg->GetBlock()->RemoveInstruction(right_neg);
HNeg* neg = new (GetGraph()->GetArena()) HNeg(binop->GetType(), binop);
binop->GetBlock()->InsertInstructionBefore(neg, binop->GetNext());
binop->ReplaceWithExceptInReplacementAtIndex(neg, 0);
RecordSimplification();
return true;
}
void InstructionSimplifierVisitor::VisitShift(HBinaryOperation* instruction) {
DCHECK(instruction->IsShl() || instruction->IsShr() || instruction->IsUShr());
HConstant* input_cst = instruction->GetConstantRight();
HInstruction* input_other = instruction->GetLeastConstantLeft();
if (input_cst != nullptr) {
if (input_cst->IsZero()) {
// Replace code looking like
// SHL dst, src, 0
// with
// src
instruction->ReplaceWith(input_other);
instruction->GetBlock()->RemoveInstruction(instruction);
}
}
}
static bool IsSubRegBitsMinusOther(HSub* sub, size_t reg_bits, HInstruction* other) {
return (sub->GetRight() == other &&
sub->GetLeft()->IsConstant() &&
(Int64FromConstant(sub->GetLeft()->AsConstant()) & (reg_bits - 1)) == 0);
}
bool InstructionSimplifierVisitor::ReplaceRotateWithRor(HBinaryOperation* op,
HUShr* ushr,
HShl* shl) {
DCHECK(op->IsAdd() || op->IsXor() || op->IsOr());
HRor* ror = new (GetGraph()->GetArena()) HRor(ushr->GetType(),
ushr->GetLeft(),
ushr->GetRight());
op->GetBlock()->ReplaceAndRemoveInstructionWith(op, ror);
if (!ushr->HasUses()) {
ushr->GetBlock()->RemoveInstruction(ushr);
}
if (!ushr->GetRight()->HasUses()) {
ushr->GetRight()->GetBlock()->RemoveInstruction(ushr->GetRight());
}
if (!shl->HasUses()) {
shl->GetBlock()->RemoveInstruction(shl);
}
if (!shl->GetRight()->HasUses()) {
shl->GetRight()->GetBlock()->RemoveInstruction(shl->GetRight());
}
return true;
}
// Try to replace a binary operation flanked by one UShr and one Shl with a bitfield rotation.
bool InstructionSimplifierVisitor::TryReplaceWithRotate(HBinaryOperation* op) {
// This simplification is currently supported on x86, x86_64, ARM and ARM64.
// TODO: Implement it for MIPS/64.
const InstructionSet instruction_set = GetGraph()->GetInstructionSet();
switch (instruction_set) {
case kArm:
case kArm64:
case kThumb2:
case kX86:
case kX86_64:
break;
default:
return false;
}
DCHECK(op->IsAdd() || op->IsXor() || op->IsOr());
HInstruction* left = op->GetLeft();
HInstruction* right = op->GetRight();
// If we have an UShr and a Shl (in either order).
if ((left->IsUShr() && right->IsShl()) || (left->IsShl() && right->IsUShr())) {
HUShr* ushr = left->IsUShr() ? left->AsUShr() : right->AsUShr();
HShl* shl = left->IsShl() ? left->AsShl() : right->AsShl();
DCHECK(Primitive::IsIntOrLongType(ushr->GetType()));
if (ushr->GetType() == shl->GetType() &&
ushr->GetLeft() == shl->GetLeft()) {
if (ushr->GetRight()->IsConstant() && shl->GetRight()->IsConstant()) {
// Shift distances are both constant, try replacing with Ror if they
// add up to the register size.
return TryReplaceWithRotateConstantPattern(op, ushr, shl);
} else if (ushr->GetRight()->IsSub() || shl->GetRight()->IsSub()) {
// Shift distances are potentially of the form x and (reg_size - x).
return TryReplaceWithRotateRegisterSubPattern(op, ushr, shl);
} else if (ushr->GetRight()->IsNeg() || shl->GetRight()->IsNeg()) {
// Shift distances are potentially of the form d and -d.
return TryReplaceWithRotateRegisterNegPattern(op, ushr, shl);
}
}
}
return false;
}
// Try replacing code looking like (x >>> #rdist OP x << #ldist):
// UShr dst, x, #rdist
// Shl tmp, x, #ldist
// OP dst, dst, tmp
// or like (x >>> #rdist OP x << #-ldist):
// UShr dst, x, #rdist
// Shl tmp, x, #-ldist
// OP dst, dst, tmp
// with
// Ror dst, x, #rdist
bool InstructionSimplifierVisitor::TryReplaceWithRotateConstantPattern(HBinaryOperation* op,
HUShr* ushr,
HShl* shl) {
DCHECK(op->IsAdd() || op->IsXor() || op->IsOr());
size_t reg_bits = Primitive::ComponentSize(ushr->GetType()) * kBitsPerByte;
size_t rdist = Int64FromConstant(ushr->GetRight()->AsConstant());
size_t ldist = Int64FromConstant(shl->GetRight()->AsConstant());
if (((ldist + rdist) & (reg_bits - 1)) == 0) {
ReplaceRotateWithRor(op, ushr, shl);
return true;
}
return false;
}
// Replace code looking like (x >>> -d OP x << d):
// Neg neg, d
// UShr dst, x, neg
// Shl tmp, x, d
// OP dst, dst, tmp
// with
// Neg neg, d
// Ror dst, x, neg
// *** OR ***
// Replace code looking like (x >>> d OP x << -d):
// UShr dst, x, d
// Neg neg, d
// Shl tmp, x, neg
// OP dst, dst, tmp
// with
// Ror dst, x, d
bool InstructionSimplifierVisitor::TryReplaceWithRotateRegisterNegPattern(HBinaryOperation* op,
HUShr* ushr,
HShl* shl) {
DCHECK(op->IsAdd() || op->IsXor() || op->IsOr());
DCHECK(ushr->GetRight()->IsNeg() || shl->GetRight()->IsNeg());
bool neg_is_left = shl->GetRight()->IsNeg();
HNeg* neg = neg_is_left ? shl->GetRight()->AsNeg() : ushr->GetRight()->AsNeg();
// And the shift distance being negated is the distance being shifted the other way.
if (neg->InputAt(0) == (neg_is_left ? ushr->GetRight() : shl->GetRight())) {
ReplaceRotateWithRor(op, ushr, shl);
}
return false;
}
// Try replacing code looking like (x >>> d OP x << (#bits - d)):
// UShr dst, x, d
// Sub ld, #bits, d
// Shl tmp, x, ld
// OP dst, dst, tmp
// with
// Ror dst, x, d
// *** OR ***
// Replace code looking like (x >>> (#bits - d) OP x << d):
// Sub rd, #bits, d
// UShr dst, x, rd
// Shl tmp, x, d
// OP dst, dst, tmp
// with
// Neg neg, d
// Ror dst, x, neg
bool InstructionSimplifierVisitor::TryReplaceWithRotateRegisterSubPattern(HBinaryOperation* op,
HUShr* ushr,
HShl* shl) {
DCHECK(op->IsAdd() || op->IsXor() || op->IsOr());
DCHECK(ushr->GetRight()->IsSub() || shl->GetRight()->IsSub());
size_t reg_bits = Primitive::ComponentSize(ushr->GetType()) * kBitsPerByte;
HInstruction* shl_shift = shl->GetRight();
HInstruction* ushr_shift = ushr->GetRight();
if ((shl_shift->IsSub() && IsSubRegBitsMinusOther(shl_shift->AsSub(), reg_bits, ushr_shift)) ||
(ushr_shift->IsSub() && IsSubRegBitsMinusOther(ushr_shift->AsSub(), reg_bits, shl_shift))) {
return ReplaceRotateWithRor(op, ushr, shl);
}
return false;
}
void InstructionSimplifierVisitor::VisitNullCheck(HNullCheck* null_check) {
HInstruction* obj = null_check->InputAt(0);
if (!obj->CanBeNull()) {
null_check->ReplaceWith(obj);
null_check->GetBlock()->RemoveInstruction(null_check);
if (stats_ != nullptr) {
stats_->RecordStat(MethodCompilationStat::kRemovedNullCheck);
}
}
}
bool InstructionSimplifierVisitor::CanEnsureNotNullAt(HInstruction* input, HInstruction* at) const {
if (!input->CanBeNull()) {
return true;
}
for (HUseIterator<HInstruction*> it(input->GetUses()); !it.Done(); it.Advance()) {
HInstruction* use = it.Current()->GetUser();
if (use->IsNullCheck() && use->StrictlyDominates(at)) {
return true;
}
}
return false;
}
// Returns whether doing a type test between the class of `object` against `klass` has
// a statically known outcome. The result of the test is stored in `outcome`.
static bool TypeCheckHasKnownOutcome(HLoadClass* klass, HInstruction* object, bool* outcome) {
DCHECK(!object->IsNullConstant()) << "Null constants should be special cased";
ReferenceTypeInfo obj_rti = object->GetReferenceTypeInfo();
ScopedObjectAccess soa(Thread::Current());
if (!obj_rti.IsValid()) {
// We run the simplifier before the reference type propagation so type info might not be
// available.
return false;
}
ReferenceTypeInfo class_rti = klass->GetLoadedClassRTI();
if (!class_rti.IsValid()) {
// Happens when the loaded class is unresolved.
return false;
}
DCHECK(class_rti.IsExact());
if (class_rti.IsSupertypeOf(obj_rti)) {
*outcome = true;
return true;
} else if (obj_rti.IsExact()) {
// The test failed at compile time so will also fail at runtime.
*outcome = false;
return true;
} else if (!class_rti.IsInterface()
&& !obj_rti.IsInterface()
&& !obj_rti.IsSupertypeOf(class_rti)) {
// Different type hierarchy. The test will fail.
*outcome = false;
return true;
}
return false;
}
void InstructionSimplifierVisitor::VisitCheckCast(HCheckCast* check_cast) {
HInstruction* object = check_cast->InputAt(0);
HLoadClass* load_class = check_cast->InputAt(1)->AsLoadClass();
if (load_class->NeedsAccessCheck()) {
// If we need to perform an access check we cannot remove the instruction.
return;
}
if (CanEnsureNotNullAt(object, check_cast)) {
check_cast->ClearMustDoNullCheck();
}
if (object->IsNullConstant()) {
check_cast->GetBlock()->RemoveInstruction(check_cast);
if (stats_ != nullptr) {
stats_->RecordStat(MethodCompilationStat::kRemovedCheckedCast);
}
return;
}
bool outcome;
if (TypeCheckHasKnownOutcome(load_class, object, &outcome)) {
if (outcome) {
check_cast->GetBlock()->RemoveInstruction(check_cast);
if (stats_ != nullptr) {
stats_->RecordStat(MethodCompilationStat::kRemovedCheckedCast);
}
if (!load_class->HasUses()) {
// We cannot rely on DCE to remove the class because the `HLoadClass` thinks it can throw.
// However, here we know that it cannot because the checkcast was successfull, hence
// the class was already loaded.
load_class->GetBlock()->RemoveInstruction(load_class);
}
} else {
// Don't do anything for exceptional cases for now. Ideally we should remove
// all instructions and blocks this instruction dominates.
}
}
}
void InstructionSimplifierVisitor::VisitInstanceOf(HInstanceOf* instruction) {
HInstruction* object = instruction->InputAt(0);
HLoadClass* load_class = instruction->InputAt(1)->AsLoadClass();
if (load_class->NeedsAccessCheck()) {
// If we need to perform an access check we cannot remove the instruction.
return;
}
bool can_be_null = true;
if (CanEnsureNotNullAt(object, instruction)) {
can_be_null = false;
instruction->ClearMustDoNullCheck();
}
HGraph* graph = GetGraph();
if (object->IsNullConstant()) {
instruction->ReplaceWith(graph->GetIntConstant(0));
instruction->GetBlock()->RemoveInstruction(instruction);
RecordSimplification();
return;
}
bool outcome;
if (TypeCheckHasKnownOutcome(load_class, object, &outcome)) {
if (outcome && can_be_null) {
// Type test will succeed, we just need a null test.
HNotEqual* test = new (graph->GetArena()) HNotEqual(graph->GetNullConstant(), object);
instruction->GetBlock()->InsertInstructionBefore(test, instruction);
instruction->ReplaceWith(test);
} else {
// We've statically determined the result of the instanceof.
instruction->ReplaceWith(graph->GetIntConstant(outcome));
}
RecordSimplification();
instruction->GetBlock()->RemoveInstruction(instruction);
if (outcome && !load_class->HasUses()) {
// We cannot rely on DCE to remove the class because the `HLoadClass` thinks it can throw.
// However, here we know that it cannot because the instanceof check was successfull, hence
// the class was already loaded.
load_class->GetBlock()->RemoveInstruction(load_class);
}
}
}
void InstructionSimplifierVisitor::VisitInstanceFieldSet(HInstanceFieldSet* instruction) {
if ((instruction->GetValue()->GetType() == Primitive::kPrimNot)
&& CanEnsureNotNullAt(instruction->GetValue(), instruction)) {
instruction->ClearValueCanBeNull();
}
}
void InstructionSimplifierVisitor::VisitStaticFieldSet(HStaticFieldSet* instruction) {
if ((instruction->GetValue()->GetType() == Primitive::kPrimNot)
&& CanEnsureNotNullAt(instruction->GetValue(), instruction)) {
instruction->ClearValueCanBeNull();
}
}
void InstructionSimplifierVisitor::VisitSuspendCheck(HSuspendCheck* check) {
HBasicBlock* block = check->GetBlock();
// Currently always keep the suspend check at entry.
if (block->IsEntryBlock()) return;
// Currently always keep suspend checks at loop entry.
if (block->IsLoopHeader() && block->GetFirstInstruction() == check) {
DCHECK(block->GetLoopInformation()->GetSuspendCheck() == check);
return;
}
// Remove the suspend check that was added at build time for the baseline
// compiler.
block->RemoveInstruction(check);
}
static HCondition* GetOppositeConditionSwapOps(ArenaAllocator* arena, HInstruction* cond) {
HInstruction *lhs = cond->InputAt(0);
HInstruction *rhs = cond->InputAt(1);
switch (cond->GetKind()) {
case HInstruction::kEqual:
return new (arena) HEqual(rhs, lhs);
case HInstruction::kNotEqual:
return new (arena) HNotEqual(rhs, lhs);
case HInstruction::kLessThan:
return new (arena) HGreaterThan(rhs, lhs);
case HInstruction::kLessThanOrEqual:
return new (arena) HGreaterThanOrEqual(rhs, lhs);
case HInstruction::kGreaterThan:
return new (arena) HLessThan(rhs, lhs);
case HInstruction::kGreaterThanOrEqual:
return new (arena) HLessThanOrEqual(rhs, lhs);
case HInstruction::kBelow:
return new (arena) HAbove(rhs, lhs);
case HInstruction::kBelowOrEqual:
return new (arena) HAboveOrEqual(rhs, lhs);
case HInstruction::kAbove:
return new (arena) HBelow(rhs, lhs);
case HInstruction::kAboveOrEqual:
return new (arena) HBelowOrEqual(rhs, lhs);
default:
LOG(FATAL) << "Unknown ConditionType " << cond->GetKind();
}
return nullptr;
}
void InstructionSimplifierVisitor::VisitEqual(HEqual* equal) {
HInstruction* input_const = equal->GetConstantRight();
if (input_const != nullptr) {
HInstruction* input_value = equal->GetLeastConstantLeft();
if (input_value->GetType() == Primitive::kPrimBoolean && input_const->IsIntConstant()) {
HBasicBlock* block = equal->GetBlock();
// We are comparing the boolean to a constant which is of type int and can
// be any constant.
if (input_const->AsIntConstant()->IsOne()) {
// Replace (bool_value == true) with bool_value
equal->ReplaceWith(input_value);
block->RemoveInstruction(equal);
RecordSimplification();
} else if (input_const->AsIntConstant()->IsZero()) {
equal->ReplaceWith(GetGraph()->InsertOppositeCondition(input_value, equal));
block->RemoveInstruction(equal);
RecordSimplification();
} else {
// Replace (bool_value == integer_not_zero_nor_one_constant) with false
equal->ReplaceWith(GetGraph()->GetIntConstant(0));
block->RemoveInstruction(equal);
RecordSimplification();
}
} else {
VisitCondition(equal);
}
} else {
VisitCondition(equal);
}
}
void InstructionSimplifierVisitor::VisitNotEqual(HNotEqual* not_equal) {
HInstruction* input_const = not_equal->GetConstantRight();
if (input_const != nullptr) {
HInstruction* input_value = not_equal->GetLeastConstantLeft();
if (input_value->GetType() == Primitive::kPrimBoolean && input_const->IsIntConstant()) {
HBasicBlock* block = not_equal->GetBlock();
// We are comparing the boolean to a constant which is of type int and can
// be any constant.
if (input_const->AsIntConstant()->IsOne()) {
not_equal->ReplaceWith(GetGraph()->InsertOppositeCondition(input_value, not_equal));
block->RemoveInstruction(not_equal);
RecordSimplification();
} else if (input_const->AsIntConstant()->IsZero()) {
// Replace (bool_value != false) with bool_value
not_equal->ReplaceWith(input_value);
block->RemoveInstruction(not_equal);
RecordSimplification();
} else {
// Replace (bool_value != integer_not_zero_nor_one_constant) with true
not_equal->ReplaceWith(GetGraph()->GetIntConstant(1));
block->RemoveInstruction(not_equal);
RecordSimplification();
}
} else {
VisitCondition(not_equal);
}
} else {
VisitCondition(not_equal);
}
}
void InstructionSimplifierVisitor::VisitBooleanNot(HBooleanNot* bool_not) {
HInstruction* parent = bool_not->InputAt(0);
if (parent->IsBooleanNot()) {
HInstruction* value = parent->InputAt(0);
// Replace (!(!bool_value)) with bool_value
bool_not->ReplaceWith(value);
bool_not->GetBlock()->RemoveInstruction(bool_not);
// It is possible that `parent` is dead at this point but we leave
// its removal to DCE for simplicity.
RecordSimplification();
}
}
void InstructionSimplifierVisitor::VisitArrayLength(HArrayLength* instruction) {
HInstruction* input = instruction->InputAt(0);
// If the array is a NewArray with constant size, replace the array length
// with the constant instruction. This helps the bounds check elimination phase.
if (input->IsNewArray()) {
input = input->InputAt(0);
if (input->IsIntConstant()) {
instruction->ReplaceWith(input);
}
}
}
void InstructionSimplifierVisitor::VisitArraySet(HArraySet* instruction) {
HInstruction* value = instruction->GetValue();
if (value->GetType() != Primitive::kPrimNot) return;
if (CanEnsureNotNullAt(value, instruction)) {
instruction->ClearValueCanBeNull();
}
if (value->IsArrayGet()) {
if (value->AsArrayGet()->GetArray() == instruction->GetArray()) {
// If the code is just swapping elements in the array, no need for a type check.
instruction->ClearNeedsTypeCheck();
return;
}
}
if (value->IsNullConstant()) {
instruction->ClearNeedsTypeCheck();
return;
}
ScopedObjectAccess soa(Thread::Current());
ReferenceTypeInfo array_rti = instruction->GetArray()->GetReferenceTypeInfo();
ReferenceTypeInfo value_rti = value->GetReferenceTypeInfo();
if (!array_rti.IsValid()) {
return;
}
if (value_rti.IsValid() && array_rti.CanArrayHold(value_rti)) {
instruction->ClearNeedsTypeCheck();
return;
}
if (array_rti.IsObjectArray()) {
if (array_rti.IsExact()) {
instruction->ClearNeedsTypeCheck();
return;
}
instruction->SetStaticTypeOfArrayIsObjectArray();
}
}
void InstructionSimplifierVisitor::VisitTypeConversion(HTypeConversion* instruction) {
if (instruction->GetResultType() == instruction->GetInputType()) {
// Remove the instruction if it's converting to the same type.
instruction->ReplaceWith(instruction->GetInput());
instruction->GetBlock()->RemoveInstruction(instruction);
}
}
void InstructionSimplifierVisitor::VisitAdd(HAdd* instruction) {
HConstant* input_cst = instruction->GetConstantRight();
HInstruction* input_other = instruction->GetLeastConstantLeft();
if ((input_cst != nullptr) && input_cst->IsZero()) {
// Replace code looking like
// ADD dst, src, 0
// with
// src
// Note that we cannot optimize `x + 0.0` to `x` for floating-point. When
// `x` is `-0.0`, the former expression yields `0.0`, while the later
// yields `-0.0`.
if (Primitive::IsIntegralType(instruction->GetType())) {
instruction->ReplaceWith(input_other);
instruction->GetBlock()->RemoveInstruction(instruction);
return;
}
}
HInstruction* left = instruction->GetLeft();
HInstruction* right = instruction->GetRight();
bool left_is_neg = left->IsNeg();
bool right_is_neg = right->IsNeg();
if (left_is_neg && right_is_neg) {
if (TryMoveNegOnInputsAfterBinop(instruction)) {
return;
}
}
HNeg* neg = left_is_neg ? left->AsNeg() : right->AsNeg();
if ((left_is_neg ^ right_is_neg) && neg->HasOnlyOneNonEnvironmentUse()) {
// Replace code looking like
// NEG tmp, b
// ADD dst, a, tmp
// with
// SUB dst, a, b
// We do not perform the optimization if the input negation has environment
// uses or multiple non-environment uses as it could lead to worse code. In
// particular, we do not want the live range of `b` to be extended if we are
// not sure the initial 'NEG' instruction can be removed.
HInstruction* other = left_is_neg ? right : left;
HSub* sub = new(GetGraph()->GetArena()) HSub(instruction->GetType(), other, neg->GetInput());
instruction->GetBlock()->ReplaceAndRemoveInstructionWith(instruction, sub);
RecordSimplification();
neg->GetBlock()->RemoveInstruction(neg);
return;
}
TryReplaceWithRotate(instruction);
}
void InstructionSimplifierVisitor::VisitAnd(HAnd* instruction) {
HConstant* input_cst = instruction->GetConstantRight();
HInstruction* input_other = instruction->GetLeastConstantLeft();
if (input_cst != nullptr) {
int64_t value = Int64FromConstant(input_cst);
if (value == -1) {
// Replace code looking like
// AND dst, src, 0xFFF...FF
// with
// src
instruction->ReplaceWith(input_other);
instruction->GetBlock()->RemoveInstruction(instruction);
RecordSimplification();
return;
}
// Eliminate And from UShr+And if the And-mask contains all the bits that
// can be non-zero after UShr. Transform Shr+And to UShr if the And-mask
// precisely clears the shifted-in sign bits.
if ((input_other->IsUShr() || input_other->IsShr()) && input_other->InputAt(1)->IsConstant()) {
size_t reg_bits = (instruction->GetResultType() == Primitive::kPrimLong) ? 64 : 32;
size_t shift = Int64FromConstant(input_other->InputAt(1)->AsConstant()) & (reg_bits - 1);
size_t num_tail_bits_set = CTZ(value + 1);
if ((num_tail_bits_set >= reg_bits - shift) && input_other->IsUShr()) {
// This AND clears only bits known to be clear, for example "(x >>> 24) & 0xff".
instruction->ReplaceWith(input_other);
instruction->GetBlock()->RemoveInstruction(instruction);
RecordSimplification();
return;
} else if ((num_tail_bits_set == reg_bits - shift) && IsPowerOfTwo(value + 1) &&
input_other->HasOnlyOneNonEnvironmentUse()) {
DCHECK(input_other->IsShr()); // For UShr, we would have taken the branch above.
// Replace SHR+AND with USHR, for example "(x >> 24) & 0xff" -> "x >>> 24".
HUShr* ushr = new (GetGraph()->GetArena()) HUShr(instruction->GetType(),
input_other->InputAt(0),
input_other->InputAt(1),
input_other->GetDexPc());
instruction->GetBlock()->ReplaceAndRemoveInstructionWith(instruction, ushr);
input_other->GetBlock()->RemoveInstruction(input_other);
RecordSimplification();
return;
}
}
}
// We assume that GVN has run before, so we only perform a pointer comparison.
// If for some reason the values are equal but the pointers are different, we
// are still correct and only miss an optimization opportunity.
if (instruction->GetLeft() == instruction->GetRight()) {
// Replace code looking like
// AND dst, src, src
// with
// src
instruction->ReplaceWith(instruction->GetLeft());
instruction->GetBlock()->RemoveInstruction(instruction);
}
}
void InstructionSimplifierVisitor::VisitGreaterThan(HGreaterThan* condition) {
VisitCondition(condition);
}
void InstructionSimplifierVisitor::VisitGreaterThanOrEqual(HGreaterThanOrEqual* condition) {
VisitCondition(condition);
}
void InstructionSimplifierVisitor::VisitLessThan(HLessThan* condition) {
VisitCondition(condition);
}
void InstructionSimplifierVisitor::VisitLessThanOrEqual(HLessThanOrEqual* condition) {
VisitCondition(condition);
}
void InstructionSimplifierVisitor::VisitBelow(HBelow* condition) {
VisitCondition(condition);
}
void InstructionSimplifierVisitor::VisitBelowOrEqual(HBelowOrEqual* condition) {
VisitCondition(condition);
}
void InstructionSimplifierVisitor::VisitAbove(HAbove* condition) {
VisitCondition(condition);
}
void InstructionSimplifierVisitor::VisitAboveOrEqual(HAboveOrEqual* condition) {
VisitCondition(condition);
}
void InstructionSimplifierVisitor::VisitCondition(HCondition* condition) {
// Reverse condition if left is constant. Our code generators prefer constant
// on the right hand side.
if (condition->GetLeft()->IsConstant() && !condition->GetRight()->IsConstant()) {
HBasicBlock* block = condition->GetBlock();
HCondition* replacement = GetOppositeConditionSwapOps(block->GetGraph()->GetArena(), condition);
// If it is a fp we must set the opposite bias.
if (replacement != nullptr) {
if (condition->IsLtBias()) {
replacement->SetBias(ComparisonBias::kGtBias);
} else if (condition->IsGtBias()) {
replacement->SetBias(ComparisonBias::kLtBias);
}
block->ReplaceAndRemoveInstructionWith(condition, replacement);
RecordSimplification();
condition = replacement;
}
}
HInstruction* left = condition->GetLeft();
HInstruction* right = condition->GetRight();
// Try to fold an HCompare into this HCondition.
// We can only replace an HCondition which compares a Compare to 0.
// Both 'dx' and 'jack' generate a compare to 0 when compiling a
// condition with a long, float or double comparison as input.
if (!left->IsCompare() || !right->IsConstant() || right->AsIntConstant()->GetValue() != 0) {
// Conversion is not possible.
return;
}
// Is the Compare only used for this purpose?
if (!left->GetUses().HasOnlyOneUse()) {
// Someone else also wants the result of the compare.
return;
}
if (!left->GetEnvUses().IsEmpty()) {
// There is a reference to the compare result in an environment. Do we really need it?
if (GetGraph()->IsDebuggable()) {
return;
}
// We have to ensure that there are no deopt points in the sequence.
if (left->HasAnyEnvironmentUseBefore(condition)) {
return;
}
}
// Clean up any environment uses from the HCompare, if any.
left->RemoveEnvironmentUsers();
// We have decided to fold the HCompare into the HCondition. Transfer the information.
condition->SetBias(left->AsCompare()->GetBias());
// Replace the operands of the HCondition.
condition->ReplaceInput(left->InputAt(0), 0);
condition->ReplaceInput(left->InputAt(1), 1);
// Remove the HCompare.
left->GetBlock()->RemoveInstruction(left);
RecordSimplification();
}
void InstructionSimplifierVisitor::VisitDiv(HDiv* instruction) {
HConstant* input_cst = instruction->GetConstantRight();
HInstruction* input_other = instruction->GetLeastConstantLeft();
Primitive::Type type = instruction->GetType();
if ((input_cst != nullptr) && input_cst->IsOne()) {
// Replace code looking like
// DIV dst, src, 1
// with
// src
instruction->ReplaceWith(input_other);
instruction->GetBlock()->RemoveInstruction(instruction);
return;
}
if ((input_cst != nullptr) && input_cst->IsMinusOne()) {
// Replace code looking like
// DIV dst, src, -1
// with
// NEG dst, src
instruction->GetBlock()->ReplaceAndRemoveInstructionWith(
instruction, new (GetGraph()->GetArena()) HNeg(type, input_other));
RecordSimplification();
return;
}
if ((input_cst != nullptr) && Primitive::IsFloatingPointType(type)) {
// Try replacing code looking like
// DIV dst, src, constant
// with
// MUL dst, src, 1 / constant
HConstant* reciprocal = nullptr;
if (type == Primitive::Primitive::kPrimDouble) {
double value = input_cst->AsDoubleConstant()->GetValue();
if (CanDivideByReciprocalMultiplyDouble(bit_cast<int64_t, double>(value))) {
reciprocal = GetGraph()->GetDoubleConstant(1.0 / value);
}
} else {
DCHECK_EQ(type, Primitive::kPrimFloat);
float value = input_cst->AsFloatConstant()->GetValue();
if (CanDivideByReciprocalMultiplyFloat(bit_cast<int32_t, float>(value))) {
reciprocal = GetGraph()->GetFloatConstant(1.0f / value);
}
}
if (reciprocal != nullptr) {
instruction->GetBlock()->ReplaceAndRemoveInstructionWith(
instruction, new (GetGraph()->GetArena()) HMul(type, input_other, reciprocal));
RecordSimplification();
return;
}
}
}
void InstructionSimplifierVisitor::VisitMul(HMul* instruction) {
HConstant* input_cst = instruction->GetConstantRight();
HInstruction* input_other = instruction->GetLeastConstantLeft();
Primitive::Type type = instruction->GetType();
HBasicBlock* block = instruction->GetBlock();
ArenaAllocator* allocator = GetGraph()->GetArena();
if (input_cst == nullptr) {
return;
}
if (input_cst->IsOne()) {
// Replace code looking like
// MUL dst, src, 1
// with
// src
instruction->ReplaceWith(input_other);
instruction->GetBlock()->RemoveInstruction(instruction);
return;
}
if (input_cst->IsMinusOne() &&
(Primitive::IsFloatingPointType(type) || Primitive::IsIntOrLongType(type))) {
// Replace code looking like
// MUL dst, src, -1
// with
// NEG dst, src
HNeg* neg = new (allocator) HNeg(type, input_other);
block->ReplaceAndRemoveInstructionWith(instruction, neg);
RecordSimplification();
return;
}
if (Primitive::IsFloatingPointType(type) &&
((input_cst->IsFloatConstant() && input_cst->AsFloatConstant()->GetValue() == 2.0f) ||
(input_cst->IsDoubleConstant() && input_cst->AsDoubleConstant()->GetValue() == 2.0))) {
// Replace code looking like
// FP_MUL dst, src, 2.0
// with
// FP_ADD dst, src, src
// The 'int' and 'long' cases are handled below.
block->ReplaceAndRemoveInstructionWith(instruction,
new (allocator) HAdd(type, input_other, input_other));
RecordSimplification();
return;
}
if (Primitive::IsIntOrLongType(type)) {
int64_t factor = Int64FromConstant(input_cst);
// Even though constant propagation also takes care of the zero case, other
// optimizations can lead to having a zero multiplication.
if (factor == 0) {
// Replace code looking like
// MUL dst, src, 0
// with
// 0
instruction->ReplaceWith(input_cst);
instruction->GetBlock()->RemoveInstruction(instruction);
} else if (IsPowerOfTwo(factor)) {
// Replace code looking like
// MUL dst, src, pow_of_2
// with
// SHL dst, src, log2(pow_of_2)
HIntConstant* shift = GetGraph()->GetIntConstant(WhichPowerOf2(factor));
HShl* shl = new(allocator) HShl(type, input_other, shift);
block->ReplaceAndRemoveInstructionWith(instruction, shl);
RecordSimplification();
} else if (IsPowerOfTwo(factor - 1)) {
// Transform code looking like
// MUL dst, src, (2^n + 1)
// into
// SHL tmp, src, n
// ADD dst, src, tmp
HShl* shl = new (allocator) HShl(type,
input_other,
GetGraph()->GetIntConstant(WhichPowerOf2(factor - 1)));
HAdd* add = new (allocator) HAdd(type, input_other, shl);
block->InsertInstructionBefore(shl, instruction);
block->ReplaceAndRemoveInstructionWith(instruction, add);
RecordSimplification();
} else if (IsPowerOfTwo(factor + 1)) {
// Transform code looking like
// MUL dst, src, (2^n - 1)
// into
// SHL tmp, src, n
// SUB dst, tmp, src
HShl* shl = new (allocator) HShl(type,
input_other,
GetGraph()->GetIntConstant(WhichPowerOf2(factor + 1)));
HSub* sub = new (allocator) HSub(type, shl, input_other);
block->InsertInstructionBefore(shl, instruction);
block->ReplaceAndRemoveInstructionWith(instruction, sub);
RecordSimplification();
}
}
}
void InstructionSimplifierVisitor::VisitNeg(HNeg* instruction) {
HInstruction* input = instruction->GetInput();
if (input->IsNeg()) {
// Replace code looking like
// NEG tmp, src
// NEG dst, tmp
// with
// src
HNeg* previous_neg = input->AsNeg();
instruction->ReplaceWith(previous_neg->GetInput());
instruction->GetBlock()->RemoveInstruction(instruction);
// We perform the optimization even if the input negation has environment
// uses since it allows removing the current instruction. But we only delete
// the input negation only if it is does not have any uses left.
if (!previous_neg->HasUses()) {
previous_neg->GetBlock()->RemoveInstruction(previous_neg);
}
RecordSimplification();
return;
}
if (input->IsSub() && input->HasOnlyOneNonEnvironmentUse() &&
!Primitive::IsFloatingPointType(input->GetType())) {
// Replace code looking like
// SUB tmp, a, b
// NEG dst, tmp
// with
// SUB dst, b, a
// We do not perform the optimization if the input subtraction has
// environment uses or multiple non-environment uses as it could lead to
// worse code. In particular, we do not want the live ranges of `a` and `b`
// to be extended if we are not sure the initial 'SUB' instruction can be
// removed.
// We do not perform optimization for fp because we could lose the sign of zero.
HSub* sub = input->AsSub();
HSub* new_sub =
new (GetGraph()->GetArena()) HSub(instruction->GetType(), sub->GetRight(), sub->GetLeft());
instruction->GetBlock()->ReplaceAndRemoveInstructionWith(instruction, new_sub);
if (!sub->HasUses()) {
sub->GetBlock()->RemoveInstruction(sub);
}
RecordSimplification();
}
}
void InstructionSimplifierVisitor::VisitNot(HNot* instruction) {
HInstruction* input = instruction->GetInput();
if (input->IsNot()) {
// Replace code looking like
// NOT tmp, src
// NOT dst, tmp
// with
// src
// We perform the optimization even if the input negation has environment
// uses since it allows removing the current instruction. But we only delete
// the input negation only if it is does not have any uses left.
HNot* previous_not = input->AsNot();
instruction->ReplaceWith(previous_not->GetInput());
instruction->GetBlock()->RemoveInstruction(instruction);
if (!previous_not->HasUses()) {
previous_not->GetBlock()->RemoveInstruction(previous_not);
}
RecordSimplification();
}
}
void InstructionSimplifierVisitor::VisitOr(HOr* instruction) {
HConstant* input_cst = instruction->GetConstantRight();
HInstruction* input_other = instruction->GetLeastConstantLeft();
if ((input_cst != nullptr) && input_cst->IsZero()) {
// Replace code looking like
// OR dst, src, 0
// with
// src
instruction->ReplaceWith(input_other);
instruction->GetBlock()->RemoveInstruction(instruction);
return;
}
// We assume that GVN has run before, so we only perform a pointer comparison.
// If for some reason the values are equal but the pointers are different, we
// are still correct and only miss an optimization opportunity.
if (instruction->GetLeft() == instruction->GetRight()) {
// Replace code looking like
// OR dst, src, src
// with
// src
instruction->ReplaceWith(instruction->GetLeft());
instruction->GetBlock()->RemoveInstruction(instruction);
return;
}
TryReplaceWithRotate(instruction);
}
void InstructionSimplifierVisitor::VisitShl(HShl* instruction) {
VisitShift(instruction);
}
void InstructionSimplifierVisitor::VisitShr(HShr* instruction) {
VisitShift(instruction);
}
void InstructionSimplifierVisitor::VisitSub(HSub* instruction) {
HConstant* input_cst = instruction->GetConstantRight();
HInstruction* input_other = instruction->GetLeastConstantLeft();
Primitive::Type type = instruction->GetType();
if (Primitive::IsFloatingPointType(type)) {
return;
}
if ((input_cst != nullptr) && input_cst->IsZero()) {
// Replace code looking like
// SUB dst, src, 0
// with
// src
// Note that we cannot optimize `x - 0.0` to `x` for floating-point. When
// `x` is `-0.0`, the former expression yields `0.0`, while the later
// yields `-0.0`.
instruction->ReplaceWith(input_other);
instruction->GetBlock()->RemoveInstruction(instruction);
return;
}
HBasicBlock* block = instruction->GetBlock();
ArenaAllocator* allocator = GetGraph()->GetArena();
HInstruction* left = instruction->GetLeft();
HInstruction* right = instruction->GetRight();
if (left->IsConstant()) {
if (Int64FromConstant(left->AsConstant()) == 0) {
// Replace code looking like
// SUB dst, 0, src
// with
// NEG dst, src
// Note that we cannot optimize `0.0 - x` to `-x` for floating-point. When
// `x` is `0.0`, the former expression yields `0.0`, while the later
// yields `-0.0`.
HNeg* neg = new (allocator) HNeg(type, right);
block->ReplaceAndRemoveInstructionWith(instruction, neg);
RecordSimplification();
return;
}
}
if (left->IsNeg() && right->IsNeg()) {
if (TryMoveNegOnInputsAfterBinop(instruction)) {
return;
}
}
if (right->IsNeg() && right->HasOnlyOneNonEnvironmentUse()) {
// Replace code looking like
// NEG tmp, b
// SUB dst, a, tmp
// with
// ADD dst, a, b
HAdd* add = new(GetGraph()->GetArena()) HAdd(type, left, right->AsNeg()->GetInput());
instruction->GetBlock()->ReplaceAndRemoveInstructionWith(instruction, add);
RecordSimplification();
right->GetBlock()->RemoveInstruction(right);
return;
}
if (left->IsNeg() && left->HasOnlyOneNonEnvironmentUse()) {
// Replace code looking like
// NEG tmp, a
// SUB dst, tmp, b
// with
// ADD tmp, a, b
// NEG dst, tmp
// The second version is not intrinsically better, but enables more
// transformations.
HAdd* add = new(GetGraph()->GetArena()) HAdd(type, left->AsNeg()->GetInput(), right);
instruction->GetBlock()->InsertInstructionBefore(add, instruction);
HNeg* neg = new (GetGraph()->GetArena()) HNeg(instruction->GetType(), add);
instruction->GetBlock()->InsertInstructionBefore(neg, instruction);
instruction->ReplaceWith(neg);
instruction->GetBlock()->RemoveInstruction(instruction);
RecordSimplification();
left->GetBlock()->RemoveInstruction(left);
}
}
void InstructionSimplifierVisitor::VisitUShr(HUShr* instruction) {
VisitShift(instruction);
}
void InstructionSimplifierVisitor::VisitXor(HXor* instruction) {
HConstant* input_cst = instruction->GetConstantRight();
HInstruction* input_other = instruction->GetLeastConstantLeft();
if ((input_cst != nullptr) && input_cst->IsZero()) {
// Replace code looking like
// XOR dst, src, 0
// with
// src
instruction->ReplaceWith(input_other);
instruction->GetBlock()->RemoveInstruction(instruction);
return;
}
if ((input_cst != nullptr) && AreAllBitsSet(input_cst)) {
// Replace code looking like
// XOR dst, src, 0xFFF...FF
// with
// NOT dst, src
HNot* bitwise_not = new (GetGraph()->GetArena()) HNot(instruction->GetType(), input_other);
instruction->GetBlock()->ReplaceAndRemoveInstructionWith(instruction, bitwise_not);
RecordSimplification();
return;
}
TryReplaceWithRotate(instruction);
}
void InstructionSimplifierVisitor::VisitFakeString(HFakeString* instruction) {
HInstruction* actual_string = nullptr;
// Find the string we need to replace this instruction with. The actual string is
// the return value of a StringFactory call.
for (HUseIterator<HInstruction*> it(instruction->GetUses()); !it.Done(); it.Advance()) {
HInstruction* use = it.Current()->GetUser();
if (use->IsInvokeStaticOrDirect()
&& use->AsInvokeStaticOrDirect()->IsStringFactoryFor(instruction)) {
use->AsInvokeStaticOrDirect()->RemoveFakeStringArgumentAsLastInput();
actual_string = use;
break;
}
}
// Check that there is no other instruction that thinks it is the factory for that string.
if (kIsDebugBuild) {
CHECK(actual_string != nullptr);
for (HUseIterator<HInstruction*> it(instruction->GetUses()); !it.Done(); it.Advance()) {
HInstruction* use = it.Current()->GetUser();
if (use->IsInvokeStaticOrDirect()) {
CHECK(!use->AsInvokeStaticOrDirect()->IsStringFactoryFor(instruction));
}
}
}
// We need to remove any environment uses of the fake string that are not dominated by
// `actual_string` to null.
for (HUseIterator<HEnvironment*> it(instruction->GetEnvUses()); !it.Done(); it.Advance()) {
HEnvironment* environment = it.Current()->GetUser();
if (!actual_string->StrictlyDominates(environment->GetHolder())) {
environment->RemoveAsUserOfInput(it.Current()->GetIndex());
environment->SetRawEnvAt(it.Current()->GetIndex(), nullptr);
}
}
// Only uses dominated by `actual_string` must remain. We can safely replace and remove
// `instruction`.
instruction->ReplaceWith(actual_string);
instruction->GetBlock()->RemoveInstruction(instruction);
}
void InstructionSimplifierVisitor::SimplifyStringEquals(HInvoke* instruction) {
HInstruction* argument = instruction->InputAt(1);
HInstruction* receiver = instruction->InputAt(0);
if (receiver == argument) {
// Because String.equals is an instance call, the receiver is
// a null check if we don't know it's null. The argument however, will
// be the actual object. So we cannot end up in a situation where both
// are equal but could be null.
DCHECK(CanEnsureNotNullAt(argument, instruction));
instruction->ReplaceWith(GetGraph()->GetIntConstant(1));
instruction->GetBlock()->RemoveInstruction(instruction);
} else {
StringEqualsOptimizations optimizations(instruction);
if (CanEnsureNotNullAt(argument, instruction)) {
optimizations.SetArgumentNotNull();
}
ScopedObjectAccess soa(Thread::Current());
ReferenceTypeInfo argument_rti = argument->GetReferenceTypeInfo();
if (argument_rti.IsValid() && argument_rti.IsStringClass()) {
optimizations.SetArgumentIsString();
}
}
}
void InstructionSimplifierVisitor::SimplifyRotate(HInvoke* invoke, bool is_left) {
DCHECK(invoke->IsInvokeStaticOrDirect());
DCHECK_EQ(invoke->GetOriginalInvokeType(), InvokeType::kStatic);
// This simplification is currently supported on x86, x86_64, ARM and ARM64.
// TODO: Implement it for MIPS/64.
const InstructionSet instruction_set = GetGraph()->GetInstructionSet();
switch (instruction_set) {
case kArm:
case kArm64:
case kThumb2:
case kX86:
case kX86_64:
break;
default:
return;
}
HInstruction* value = invoke->InputAt(0);
HInstruction* distance = invoke->InputAt(1);
// Replace the invoke with an HRor.
if (is_left) {
distance = new (GetGraph()->GetArena()) HNeg(distance->GetType(), distance);
invoke->GetBlock()->InsertInstructionBefore(distance, invoke);
}
HRor* ror = new (GetGraph()->GetArena()) HRor(value->GetType(), value, distance);
invoke->GetBlock()->ReplaceAndRemoveInstructionWith(invoke, ror);
// Remove ClinitCheck and LoadClass, if possible.
HInstruction* clinit = invoke->InputAt(invoke->InputCount() - 1);
if (clinit->IsClinitCheck() && !clinit->HasUses()) {
clinit->GetBlock()->RemoveInstruction(clinit);
HInstruction* ldclass = clinit->InputAt(0);
if (ldclass->IsLoadClass() && !ldclass->HasUses()) {
ldclass->GetBlock()->RemoveInstruction(ldclass);
}
}
}
static bool IsArrayLengthOf(HInstruction* potential_length, HInstruction* potential_array) {
if (potential_length->IsArrayLength()) {
return potential_length->InputAt(0) == potential_array;
}
if (potential_array->IsNewArray()) {
return potential_array->InputAt(0) == potential_length;
}
return false;
}
void InstructionSimplifierVisitor::SimplifySystemArrayCopy(HInvoke* instruction) {
HInstruction* source = instruction->InputAt(0);
HInstruction* destination = instruction->InputAt(2);
HInstruction* count = instruction->InputAt(4);
SystemArrayCopyOptimizations optimizations(instruction);
if (CanEnsureNotNullAt(source, instruction)) {
optimizations.SetSourceIsNotNull();
}
if (CanEnsureNotNullAt(destination, instruction)) {
optimizations.SetDestinationIsNotNull();
}
if (destination == source) {
optimizations.SetDestinationIsSource();
}
if (IsArrayLengthOf(count, source)) {
optimizations.SetCountIsSourceLength();
}
if (IsArrayLengthOf(count, destination)) {
optimizations.SetCountIsDestinationLength();
}
{
ScopedObjectAccess soa(Thread::Current());
ReferenceTypeInfo destination_rti = destination->GetReferenceTypeInfo();
if (destination_rti.IsValid()) {
if (destination_rti.IsObjectArray()) {
if (destination_rti.IsExact()) {
optimizations.SetDoesNotNeedTypeCheck();
}
optimizations.SetDestinationIsTypedObjectArray();
}
if (destination_rti.IsPrimitiveArrayClass()) {
optimizations.SetDestinationIsPrimitiveArray();
} else if (destination_rti.IsNonPrimitiveArrayClass()) {
optimizations.SetDestinationIsNonPrimitiveArray();
}
}
ReferenceTypeInfo source_rti = source->GetReferenceTypeInfo();
if (source_rti.IsValid()) {
if (destination_rti.IsValid() && destination_rti.CanArrayHoldValuesOf(source_rti)) {
optimizations.SetDoesNotNeedTypeCheck();
}
if (source_rti.IsPrimitiveArrayClass()) {
optimizations.SetSourceIsPrimitiveArray();
} else if (source_rti.IsNonPrimitiveArrayClass()) {
optimizations.SetSourceIsNonPrimitiveArray();
}
}
}
}
void InstructionSimplifierVisitor::VisitInvoke(HInvoke* instruction) {
if (instruction->GetIntrinsic() == Intrinsics::kStringEquals) {
SimplifyStringEquals(instruction);
} else if (instruction->GetIntrinsic() == Intrinsics::kSystemArrayCopy) {
SimplifySystemArrayCopy(instruction);
} else if (instruction->GetIntrinsic() == Intrinsics::kIntegerRotateRight ||
instruction->GetIntrinsic() == Intrinsics::kLongRotateRight) {
SimplifyRotate(instruction, false);
} else if (instruction->GetIntrinsic() == Intrinsics::kIntegerRotateLeft ||
instruction->GetIntrinsic() == Intrinsics::kLongRotateLeft) {
SimplifyRotate(instruction, true);
}
}
void InstructionSimplifierVisitor::VisitDeoptimize(HDeoptimize* deoptimize) {
HInstruction* cond = deoptimize->InputAt(0);
if (cond->IsConstant()) {
if (cond->AsIntConstant()->IsZero()) {
// Never deopt: instruction can be removed.
deoptimize->GetBlock()->RemoveInstruction(deoptimize);
} else {
// Always deopt.
}
}
}
} // namespace art