/*
* Copyright (C) 2015 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 "pc_relative_fixups_x86.h"
#include "code_generator_x86.h"
#include "intrinsics_x86.h"
namespace art {
namespace x86 {
/**
* Finds instructions that need the constant area base as an input.
*/
class PCRelativeHandlerVisitor : public HGraphVisitor {
public:
PCRelativeHandlerVisitor(HGraph* graph, CodeGenerator* codegen)
: HGraphVisitor(graph),
codegen_(down_cast<CodeGeneratorX86*>(codegen)),
base_(nullptr) {}
void MoveBaseIfNeeded() {
if (base_ != nullptr) {
// Bring the base closer to the first use (previously, it was in the
// entry block) and relieve some pressure on the register allocator
// while avoiding recalculation of the base in a loop.
base_->MoveBeforeFirstUserAndOutOfLoops();
}
}
private:
void VisitAdd(HAdd* add) OVERRIDE {
BinaryFP(add);
}
void VisitSub(HSub* sub) OVERRIDE {
BinaryFP(sub);
}
void VisitMul(HMul* mul) OVERRIDE {
BinaryFP(mul);
}
void VisitDiv(HDiv* div) OVERRIDE {
BinaryFP(div);
}
void VisitCompare(HCompare* compare) OVERRIDE {
BinaryFP(compare);
}
void VisitReturn(HReturn* ret) OVERRIDE {
HConstant* value = ret->InputAt(0)->AsConstant();
if ((value != nullptr && Primitive::IsFloatingPointType(value->GetType()))) {
ReplaceInput(ret, value, 0, true);
}
}
void VisitInvokeStaticOrDirect(HInvokeStaticOrDirect* invoke) OVERRIDE {
HandleInvoke(invoke);
}
void VisitInvokeVirtual(HInvokeVirtual* invoke) OVERRIDE {
HandleInvoke(invoke);
}
void VisitInvokeInterface(HInvokeInterface* invoke) OVERRIDE {
HandleInvoke(invoke);
}
void VisitLoadString(HLoadString* load_string) OVERRIDE {
HLoadString::LoadKind load_kind = load_string->GetLoadKind();
if (load_kind == HLoadString::LoadKind::kBootImageLinkTimePcRelative ||
load_kind == HLoadString::LoadKind::kDexCachePcRelative) {
InitializePCRelativeBasePointer();
load_string->AddSpecialInput(base_);
}
}
void BinaryFP(HBinaryOperation* bin) {
HConstant* rhs = bin->InputAt(1)->AsConstant();
if (rhs != nullptr && Primitive::IsFloatingPointType(rhs->GetType())) {
ReplaceInput(bin, rhs, 1, false);
}
}
void VisitEqual(HEqual* cond) OVERRIDE {
BinaryFP(cond);
}
void VisitNotEqual(HNotEqual* cond) OVERRIDE {
BinaryFP(cond);
}
void VisitLessThan(HLessThan* cond) OVERRIDE {
BinaryFP(cond);
}
void VisitLessThanOrEqual(HLessThanOrEqual* cond) OVERRIDE {
BinaryFP(cond);
}
void VisitGreaterThan(HGreaterThan* cond) OVERRIDE {
BinaryFP(cond);
}
void VisitGreaterThanOrEqual(HGreaterThanOrEqual* cond) OVERRIDE {
BinaryFP(cond);
}
void VisitNeg(HNeg* neg) OVERRIDE {
if (Primitive::IsFloatingPointType(neg->GetType())) {
// We need to replace the HNeg with a HX86FPNeg in order to address the constant area.
InitializePCRelativeBasePointer();
HGraph* graph = GetGraph();
HBasicBlock* block = neg->GetBlock();
HX86FPNeg* x86_fp_neg = new (graph->GetArena()) HX86FPNeg(
neg->GetType(),
neg->InputAt(0),
base_,
neg->GetDexPc());
block->ReplaceAndRemoveInstructionWith(neg, x86_fp_neg);
}
}
void VisitPackedSwitch(HPackedSwitch* switch_insn) OVERRIDE {
if (switch_insn->GetNumEntries() <=
InstructionCodeGeneratorX86::kPackedSwitchJumpTableThreshold) {
return;
}
// We need to replace the HPackedSwitch with a HX86PackedSwitch in order to
// address the constant area.
InitializePCRelativeBasePointer();
HGraph* graph = GetGraph();
HBasicBlock* block = switch_insn->GetBlock();
HX86PackedSwitch* x86_switch = new (graph->GetArena()) HX86PackedSwitch(
switch_insn->GetStartValue(),
switch_insn->GetNumEntries(),
switch_insn->InputAt(0),
base_,
switch_insn->GetDexPc());
block->ReplaceAndRemoveInstructionWith(switch_insn, x86_switch);
}
void InitializePCRelativeBasePointer() {
// Ensure we only initialize the pointer once.
if (base_ != nullptr) {
return;
}
// Insert the base at the start of the entry block, move it to a better
// position later in MoveBaseIfNeeded().
base_ = new (GetGraph()->GetArena()) HX86ComputeBaseMethodAddress();
HBasicBlock* entry_block = GetGraph()->GetEntryBlock();
entry_block->InsertInstructionBefore(base_, entry_block->GetFirstInstruction());
DCHECK(base_ != nullptr);
}
void ReplaceInput(HInstruction* insn, HConstant* value, int input_index, bool materialize) {
InitializePCRelativeBasePointer();
HX86LoadFromConstantTable* load_constant =
new (GetGraph()->GetArena()) HX86LoadFromConstantTable(base_, value);
if (!materialize) {
load_constant->MarkEmittedAtUseSite();
}
insn->GetBlock()->InsertInstructionBefore(load_constant, insn);
insn->ReplaceInput(load_constant, input_index);
}
void HandleInvoke(HInvoke* invoke) {
// If this is an invoke-static/-direct with PC-relative dex cache array
// addressing, we need the PC-relative address base.
HInvokeStaticOrDirect* invoke_static_or_direct = invoke->AsInvokeStaticOrDirect();
// We can't add a pointer to the constant area if we already have a current
// method pointer. This may arise when sharpening doesn't remove the current
// method pointer from the invoke.
if (invoke_static_or_direct != nullptr &&
invoke_static_or_direct->HasCurrentMethodInput()) {
DCHECK(!invoke_static_or_direct->HasPcRelativeDexCache());
return;
}
bool base_added = false;
if (invoke_static_or_direct != nullptr &&
invoke_static_or_direct->HasPcRelativeDexCache() &&
!WillHaveCallFreeIntrinsicsCodeGen(invoke)) {
InitializePCRelativeBasePointer();
// Add the extra parameter base_.
invoke_static_or_direct->AddSpecialInput(base_);
base_added = true;
}
// Ensure that we can load FP arguments from the constant area.
for (size_t i = 0, e = invoke->InputCount(); i < e; i++) {
HConstant* input = invoke->InputAt(i)->AsConstant();
if (input != nullptr && Primitive::IsFloatingPointType(input->GetType())) {
ReplaceInput(invoke, input, i, true);
}
}
// These intrinsics need the constant area.
switch (invoke->GetIntrinsic()) {
case Intrinsics::kMathAbsDouble:
case Intrinsics::kMathAbsFloat:
case Intrinsics::kMathMaxDoubleDouble:
case Intrinsics::kMathMaxFloatFloat:
case Intrinsics::kMathMinDoubleDouble:
case Intrinsics::kMathMinFloatFloat:
if (!base_added) {
DCHECK(invoke_static_or_direct != nullptr);
DCHECK(!invoke_static_or_direct->HasCurrentMethodInput());
InitializePCRelativeBasePointer();
invoke_static_or_direct->AddSpecialInput(base_);
}
break;
default:
break;
}
}
bool WillHaveCallFreeIntrinsicsCodeGen(HInvoke* invoke) {
if (invoke->GetIntrinsic() != Intrinsics::kNone) {
// This invoke may have intrinsic code generation defined. However, we must
// now also determine if this code generation is truly there and call-free
// (not unimplemented, no bail on instruction features, or call on slow path).
// This is done by actually calling the locations builder on the instruction
// and clearing out the locations once result is known. We assume this
// call only has creating locations as side effects!
IntrinsicLocationsBuilderX86 builder(codegen_);
bool success = builder.TryDispatch(invoke) && !invoke->GetLocations()->CanCall();
invoke->SetLocations(nullptr);
return success;
}
return false;
}
CodeGeneratorX86* codegen_;
// The generated HX86ComputeBaseMethodAddress in the entry block needed as an
// input to the HX86LoadFromConstantTable instructions.
HX86ComputeBaseMethodAddress* base_;
};
void PcRelativeFixups::Run() {
if (graph_->HasIrreducibleLoops()) {
// Do not run this optimization, as irreducible loops do not work with an instruction
// that can be live-in at the irreducible loop header.
return;
}
PCRelativeHandlerVisitor visitor(graph_, codegen_);
visitor.VisitInsertionOrder();
visitor.MoveBaseIfNeeded();
}
} // namespace x86
} // namespace art