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/*
* Copyright (C) 2011 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 "dex_to_dex_compiler.h"
#include "android-base/stringprintf.h"
#include "art_field-inl.h"
#include "art_method-inl.h"
#include "base/logging.h"
#include "base/mutex.h"
#include "compiled_method.h"
#include "dex_file-inl.h"
#include "dex_instruction-inl.h"
#include "driver/compiler_driver.h"
#include "driver/dex_compilation_unit.h"
#include "mirror/class-inl.h"
#include "mirror/dex_cache.h"
#include "thread-inl.h"
namespace art {
namespace optimizer {
using android::base::StringPrintf;
// Controls quickening activation.
const bool kEnableQuickening = true;
// Control check-cast elision.
const bool kEnableCheckCastEllision = true;
struct QuickenedInfo {
QuickenedInfo(uint32_t pc, uint16_t index) : dex_pc(pc), dex_member_index(index) {}
uint32_t dex_pc;
uint16_t dex_member_index;
};
class DexCompiler {
public:
DexCompiler(art::CompilerDriver& compiler,
const DexCompilationUnit& unit,
DexToDexCompilationLevel dex_to_dex_compilation_level)
: driver_(compiler),
unit_(unit),
dex_to_dex_compilation_level_(dex_to_dex_compilation_level) {}
~DexCompiler() {}
void Compile();
const std::vector<QuickenedInfo>& GetQuickenedInfo() const {
return quickened_info_;
}
private:
const DexFile& GetDexFile() const {
return *unit_.GetDexFile();
}
bool PerformOptimizations() const {
return dex_to_dex_compilation_level_ >= DexToDexCompilationLevel::kOptimize;
}
// Compiles a RETURN-VOID into a RETURN-VOID-BARRIER within a constructor where
// a barrier is required.
void CompileReturnVoid(Instruction* inst, uint32_t dex_pc);
// Compiles a CHECK-CAST into 2 NOP instructions if it is known to be safe. In
// this case, returns the second NOP instruction pointer. Otherwise, returns
// the given "inst".
Instruction* CompileCheckCast(Instruction* inst, uint32_t dex_pc);
// Compiles a field access into a quick field access.
// The field index is replaced by an offset within an Object where we can read
// from / write to this field. Therefore, this does not involve any resolution
// at runtime.
// Since the field index is encoded with 16 bits, we can replace it only if the
// field offset can be encoded with 16 bits too.
void CompileInstanceFieldAccess(Instruction* inst, uint32_t dex_pc,
Instruction::Code new_opcode, bool is_put);
// Compiles a virtual method invocation into a quick virtual method invocation.
// The method index is replaced by the vtable index where the corresponding
// Executable can be found. Therefore, this does not involve any resolution
// at runtime.
// Since the method index is encoded with 16 bits, we can replace it only if the
// vtable index can be encoded with 16 bits too.
void CompileInvokeVirtual(Instruction* inst, uint32_t dex_pc,
Instruction::Code new_opcode, bool is_range);
CompilerDriver& driver_;
const DexCompilationUnit& unit_;
const DexToDexCompilationLevel dex_to_dex_compilation_level_;
// Filled by the compiler when quickening, in order to encode that information
// in the .oat file. The runtime will use that information to get to the original
// opcodes.
std::vector<QuickenedInfo> quickened_info_;
DISALLOW_COPY_AND_ASSIGN(DexCompiler);
};
void DexCompiler::Compile() {
DCHECK_GE(dex_to_dex_compilation_level_, DexToDexCompilationLevel::kRequired);
const DexFile::CodeItem* code_item = unit_.GetCodeItem();
const uint16_t* insns = code_item->insns_;
const uint32_t insns_size = code_item->insns_size_in_code_units_;
Instruction* inst = const_cast<Instruction*>(Instruction::At(insns));
for (uint32_t dex_pc = 0; dex_pc < insns_size;
inst = const_cast<Instruction*>(inst->Next()), dex_pc = inst->GetDexPc(insns)) {
switch (inst->Opcode()) {
case Instruction::RETURN_VOID:
CompileReturnVoid(inst, dex_pc);
break;
case Instruction::CHECK_CAST:
inst = CompileCheckCast(inst, dex_pc);
break;
case Instruction::IGET:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IGET_QUICK, false);
break;
case Instruction::IGET_WIDE:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IGET_WIDE_QUICK, false);
break;
case Instruction::IGET_OBJECT:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IGET_OBJECT_QUICK, false);
break;
case Instruction::IGET_BOOLEAN:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IGET_BOOLEAN_QUICK, false);
break;
case Instruction::IGET_BYTE:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IGET_BYTE_QUICK, false);
break;
case Instruction::IGET_CHAR:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IGET_CHAR_QUICK, false);
break;
case Instruction::IGET_SHORT:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IGET_SHORT_QUICK, false);
break;
case Instruction::IPUT:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IPUT_QUICK, true);
break;
case Instruction::IPUT_BOOLEAN:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IPUT_BOOLEAN_QUICK, true);
break;
case Instruction::IPUT_BYTE:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IPUT_BYTE_QUICK, true);
break;
case Instruction::IPUT_CHAR:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IPUT_CHAR_QUICK, true);
break;
case Instruction::IPUT_SHORT:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IPUT_SHORT_QUICK, true);
break;
case Instruction::IPUT_WIDE:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IPUT_WIDE_QUICK, true);
break;
case Instruction::IPUT_OBJECT:
CompileInstanceFieldAccess(inst, dex_pc, Instruction::IPUT_OBJECT_QUICK, true);
break;
case Instruction::INVOKE_VIRTUAL:
CompileInvokeVirtual(inst, dex_pc, Instruction::INVOKE_VIRTUAL_QUICK, false);
break;
case Instruction::INVOKE_VIRTUAL_RANGE:
CompileInvokeVirtual(inst, dex_pc, Instruction::INVOKE_VIRTUAL_RANGE_QUICK, true);
break;
default:
// Nothing to do.
break;
}
}
}
void DexCompiler::CompileReturnVoid(Instruction* inst, uint32_t dex_pc) {
DCHECK_EQ(inst->Opcode(), Instruction::RETURN_VOID);
if (unit_.IsConstructor()) {
// Are we compiling a non clinit constructor which needs a barrier ?
if (!unit_.IsStatic() &&
driver_.RequiresConstructorBarrier(Thread::Current(), unit_.GetDexFile(),
unit_.GetClassDefIndex())) {
return;
}
}
// Replace RETURN_VOID by RETURN_VOID_NO_BARRIER.
VLOG(compiler) << "Replacing " << Instruction::Name(inst->Opcode())
<< " by " << Instruction::Name(Instruction::RETURN_VOID_NO_BARRIER)
<< " at dex pc " << StringPrintf("0x%x", dex_pc) << " in method "
<< GetDexFile().PrettyMethod(unit_.GetDexMethodIndex(), true);
inst->SetOpcode(Instruction::RETURN_VOID_NO_BARRIER);
}
Instruction* DexCompiler::CompileCheckCast(Instruction* inst, uint32_t dex_pc) {
if (!kEnableCheckCastEllision || !PerformOptimizations()) {
return inst;
}
if (!driver_.IsSafeCast(&unit_, dex_pc)) {
return inst;
}
// Ok, this is a safe cast. Since the "check-cast" instruction size is 2 code
// units and a "nop" instruction size is 1 code unit, we need to replace it by
// 2 consecutive NOP instructions.
// Because the caller loops over instructions by calling Instruction::Next onto
// the current instruction, we need to return the 2nd NOP instruction. Indeed,
// its next instruction is the former check-cast's next instruction.
VLOG(compiler) << "Removing " << Instruction::Name(inst->Opcode())
<< " by replacing it with 2 NOPs at dex pc "
<< StringPrintf("0x%x", dex_pc) << " in method "
<< GetDexFile().PrettyMethod(unit_.GetDexMethodIndex(), true);
quickened_info_.push_back(QuickenedInfo(dex_pc, inst->VRegA_21c()));
quickened_info_.push_back(QuickenedInfo(dex_pc, inst->VRegB_21c()));
// We are modifying 4 consecutive bytes.
inst->SetOpcode(Instruction::NOP);
inst->SetVRegA_10x(0u); // keep compliant with verifier.
// Get to next instruction which is the second half of check-cast and replace
// it by a NOP.
inst = const_cast<Instruction*>(inst->Next());
inst->SetOpcode(Instruction::NOP);
inst->SetVRegA_10x(0u); // keep compliant with verifier.
return inst;
}
void DexCompiler::CompileInstanceFieldAccess(Instruction* inst,
uint32_t dex_pc,
Instruction::Code new_opcode,
bool is_put) {
if (!kEnableQuickening || !PerformOptimizations()) {
return;
}
uint32_t field_idx = inst->VRegC_22c();
MemberOffset field_offset(0u);
bool is_volatile;
bool fast_path = driver_.ComputeInstanceFieldInfo(field_idx, &unit_, is_put,
&field_offset, &is_volatile);
if (fast_path && !is_volatile && IsUint<16>(field_offset.Int32Value())) {
VLOG(compiler) << "Quickening " << Instruction::Name(inst->Opcode())
<< " to " << Instruction::Name(new_opcode)
<< " by replacing field index " << field_idx
<< " by field offset " << field_offset.Int32Value()
<< " at dex pc " << StringPrintf("0x%x", dex_pc) << " in method "
<< GetDexFile().PrettyMethod(unit_.GetDexMethodIndex(), true);
// We are modifying 4 consecutive bytes.
inst->SetOpcode(new_opcode);
// Replace field index by field offset.
inst->SetVRegC_22c(static_cast<uint16_t>(field_offset.Int32Value()));
quickened_info_.push_back(QuickenedInfo(dex_pc, field_idx));
}
}
void DexCompiler::CompileInvokeVirtual(Instruction* inst, uint32_t dex_pc,
Instruction::Code new_opcode, bool is_range) {
if (!kEnableQuickening || !PerformOptimizations()) {
return;
}
uint32_t method_idx = is_range ? inst->VRegB_3rc() : inst->VRegB_35c();
ScopedObjectAccess soa(Thread::Current());
StackHandleScope<1> hs(soa.Self());
Handle<mirror::ClassLoader> class_loader(hs.NewHandle(
soa.Decode<mirror::ClassLoader>(unit_.GetClassLoader())));
ClassLinker* class_linker = unit_.GetClassLinker();
ArtMethod* resolved_method = class_linker->ResolveMethod<ClassLinker::kForceICCECheck>(
GetDexFile(),
method_idx,
unit_.GetDexCache(),
class_loader,
/* referrer */ nullptr,
kVirtual);
if (UNLIKELY(resolved_method == nullptr)) {
// Clean up any exception left by type resolution.
soa.Self()->ClearException();
return;
}
uint32_t vtable_idx = resolved_method->GetMethodIndex();
DCHECK(IsUint<16>(vtable_idx));
VLOG(compiler) << "Quickening " << Instruction::Name(inst->Opcode())
<< "(" << GetDexFile().PrettyMethod(method_idx, true) << ")"
<< " to " << Instruction::Name(new_opcode)
<< " by replacing method index " << method_idx
<< " by vtable index " << vtable_idx
<< " at dex pc " << StringPrintf("0x%x", dex_pc) << " in method "
<< GetDexFile().PrettyMethod(unit_.GetDexMethodIndex(), true);
// We are modifying 4 consecutive bytes.
inst->SetOpcode(new_opcode);
// Replace method index by vtable index.
if (is_range) {
inst->SetVRegB_3rc(static_cast<uint16_t>(vtable_idx));
} else {
inst->SetVRegB_35c(static_cast<uint16_t>(vtable_idx));
}
quickened_info_.push_back(QuickenedInfo(dex_pc, method_idx));
}
CompiledMethod* ArtCompileDEX(
CompilerDriver* driver,
const DexFile::CodeItem* code_item,
uint32_t access_flags,
InvokeType invoke_type ATTRIBUTE_UNUSED,
uint16_t class_def_idx,
uint32_t method_idx,
jobject class_loader,
const DexFile& dex_file,
DexToDexCompilationLevel dex_to_dex_compilation_level) {
DCHECK(driver != nullptr);
if (dex_to_dex_compilation_level != DexToDexCompilationLevel::kDontDexToDexCompile) {
ScopedObjectAccess soa(Thread::Current());
StackHandleScope<1> hs(soa.Self());
ClassLinker* const class_linker = Runtime::Current()->GetClassLinker();
art::DexCompilationUnit unit(
class_loader,
class_linker,
dex_file,
code_item,
class_def_idx,
method_idx,
access_flags,
driver->GetVerifiedMethod(&dex_file, method_idx),
hs.NewHandle(class_linker->FindDexCache(soa.Self(), dex_file)));
art::optimizer::DexCompiler dex_compiler(*driver, unit, dex_to_dex_compilation_level);
dex_compiler.Compile();
if (dex_compiler.GetQuickenedInfo().empty()) {
// No need to create a CompiledMethod if there are no quickened opcodes.
return nullptr;
}
// Create a `CompiledMethod`, with the quickened information in the vmap table.
Leb128EncodingVector<> builder;
for (QuickenedInfo info : dex_compiler.GetQuickenedInfo()) {
builder.PushBackUnsigned(info.dex_pc);
builder.PushBackUnsigned(info.dex_member_index);
}
InstructionSet instruction_set = driver->GetInstructionSet();
if (instruction_set == kThumb2) {
// Don't use the thumb2 instruction set to avoid the one off code delta.
instruction_set = kArm;
}
return CompiledMethod::SwapAllocCompiledMethod(
driver,
instruction_set,
ArrayRef<const uint8_t>(), // no code
0,
0,
0,
ArrayRef<const SrcMapElem>(), // src_mapping_table
ArrayRef<const uint8_t>(builder.GetData()), // vmap_table
ArrayRef<const uint8_t>(), // cfi data
ArrayRef<const LinkerPatch>());
}
return nullptr;
}
} // namespace optimizer
} // namespace art