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android / platform / art / 98e6ce4 / . / compiler / dex / mir_optimization.cc
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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 "base/bit_vector-inl.h"
#include "base/logging.h"
#include "base/scoped_arena_containers.h"
#include "class_linker-inl.h"
#include "dataflow_iterator-inl.h"
#include "dex/verified_method.h"
#include "dex_flags.h"
#include "driver/compiler_driver.h"
#include "driver/dex_compilation_unit.h"
#include "global_value_numbering.h"
#include "gvn_dead_code_elimination.h"
#include "local_value_numbering.h"
#include "mir_field_info.h"
#include "mirror/string.h"
#include "quick/dex_file_method_inliner.h"
#include "quick/dex_file_to_method_inliner_map.h"
#include "stack.h"
#include "thread-inl.h"
#include "type_inference.h"
#include "utils.h"
namespace art {
static unsigned int Predecessors(BasicBlock* bb) {
return bb->predecessors.size();
}
/* Setup a constant value for opcodes thare have the DF_SETS_CONST attribute */
void MIRGraph::SetConstant(int32_t ssa_reg, int32_t value) {
is_constant_v_->SetBit(ssa_reg);
constant_values_[ssa_reg] = value;
reg_location_[ssa_reg].is_const = true;
}
void MIRGraph::SetConstantWide(int32_t ssa_reg, int64_t value) {
is_constant_v_->SetBit(ssa_reg);
is_constant_v_->SetBit(ssa_reg + 1);
constant_values_[ssa_reg] = Low32Bits(value);
constant_values_[ssa_reg + 1] = High32Bits(value);
reg_location_[ssa_reg].is_const = true;
reg_location_[ssa_reg + 1].is_const = true;
}
void MIRGraph::DoConstantPropagation(BasicBlock* bb) {
MIR* mir;
for (mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
// Skip pass if BB has MIR without SSA representation.
if (mir->ssa_rep == nullptr) {
return;
}
uint64_t df_attributes = GetDataFlowAttributes(mir);
MIR::DecodedInstruction* d_insn = &mir->dalvikInsn;
if (!(df_attributes & DF_HAS_DEFS)) continue;
/* Handle instructions that set up constants directly */
if (df_attributes & DF_SETS_CONST) {
if (df_attributes & DF_DA) {
int32_t vB = static_cast<int32_t>(d_insn->vB);
switch (d_insn->opcode) {
case Instruction::CONST_4:
case Instruction::CONST_16:
case Instruction::CONST:
SetConstant(mir->ssa_rep->defs[0], vB);
break;
case Instruction::CONST_HIGH16:
SetConstant(mir->ssa_rep->defs[0], vB << 16);
break;
case Instruction::CONST_WIDE_16:
case Instruction::CONST_WIDE_32:
SetConstantWide(mir->ssa_rep->defs[0], static_cast<int64_t>(vB));
break;
case Instruction::CONST_WIDE:
SetConstantWide(mir->ssa_rep->defs[0], d_insn->vB_wide);
break;
case Instruction::CONST_WIDE_HIGH16:
SetConstantWide(mir->ssa_rep->defs[0], static_cast<int64_t>(vB) << 48);
break;
default:
break;
}
}
/* Handle instructions that set up constants directly */
} else if (df_attributes & DF_IS_MOVE) {
int i;
for (i = 0; i < mir->ssa_rep->num_uses; i++) {
if (!is_constant_v_->IsBitSet(mir->ssa_rep->uses[i])) break;
}
/* Move a register holding a constant to another register */
if (i == mir->ssa_rep->num_uses) {
SetConstant(mir->ssa_rep->defs[0], constant_values_[mir->ssa_rep->uses[0]]);
if (df_attributes & DF_A_WIDE) {
SetConstant(mir->ssa_rep->defs[1], constant_values_[mir->ssa_rep->uses[1]]);
}
}
}
}
/* TODO: implement code to handle arithmetic operations */
}
/* Advance to next strictly dominated MIR node in an extended basic block */
MIR* MIRGraph::AdvanceMIR(BasicBlock** p_bb, MIR* mir) {
BasicBlock* bb = *p_bb;
if (mir != nullptr) {
mir = mir->next;
while (mir == nullptr) {
bb = GetBasicBlock(bb->fall_through);
if ((bb == nullptr) || Predecessors(bb) != 1) {
// mir is null and we cannot proceed further.
break;
} else {
*p_bb = bb;
mir = bb->first_mir_insn;
}
}
}
return mir;
}
/*
* To be used at an invoke mir. If the logically next mir node represents
* a move-result, return it. Else, return nullptr. If a move-result exists,
* it is required to immediately follow the invoke with no intervening
* opcodes or incoming arcs. However, if the result of the invoke is not
* used, a move-result may not be present.
*/
MIR* MIRGraph::FindMoveResult(BasicBlock* bb, MIR* mir) {
BasicBlock* tbb = bb;
mir = AdvanceMIR(&tbb, mir);
while (mir != nullptr) {
if ((mir->dalvikInsn.opcode == Instruction::MOVE_RESULT) ||
(mir->dalvikInsn.opcode == Instruction::MOVE_RESULT_OBJECT) ||
(mir->dalvikInsn.opcode == Instruction::MOVE_RESULT_WIDE)) {
break;
}
// Keep going if pseudo op, otherwise terminate
if (MIR::DecodedInstruction::IsPseudoMirOp(mir->dalvikInsn.opcode)) {
mir = AdvanceMIR(&tbb, mir);
} else {
mir = nullptr;
}
}
return mir;
}
BasicBlock* MIRGraph::NextDominatedBlock(BasicBlock* bb) {
if (bb->block_type == kDead) {
return nullptr;
}
DCHECK((bb->block_type == kEntryBlock) || (bb->block_type == kDalvikByteCode)
|| (bb->block_type == kExitBlock));
BasicBlock* bb_taken = GetBasicBlock(bb->taken);
BasicBlock* bb_fall_through = GetBasicBlock(bb->fall_through);
if (((bb_fall_through == nullptr) && (bb_taken != nullptr)) &&
((bb_taken->block_type == kDalvikByteCode) || (bb_taken->block_type == kExitBlock))) {
// Follow simple unconditional branches.
bb = bb_taken;
} else {
// Follow simple fallthrough
bb = (bb_taken != nullptr) ? nullptr : bb_fall_through;
}
if (bb == nullptr || (Predecessors(bb) != 1)) {
return nullptr;
}
DCHECK((bb->block_type == kDalvikByteCode) || (bb->block_type == kExitBlock));
return bb;
}
static MIR* FindPhi(BasicBlock* bb, int ssa_name) {
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
if (static_cast<int>(mir->dalvikInsn.opcode) == kMirOpPhi) {
for (int i = 0; i < mir->ssa_rep->num_uses; i++) {
if (mir->ssa_rep->uses[i] == ssa_name) {
return mir;
}
}
}
}
return nullptr;
}
static SelectInstructionKind SelectKind(MIR* mir) {
// Work with the case when mir is null.
if (mir == nullptr) {
return kSelectNone;
}
switch (mir->dalvikInsn.opcode) {
case Instruction::MOVE:
case Instruction::MOVE_OBJECT:
case Instruction::MOVE_16:
case Instruction::MOVE_OBJECT_16:
case Instruction::MOVE_FROM16:
case Instruction::MOVE_OBJECT_FROM16:
return kSelectMove;
case Instruction::CONST:
case Instruction::CONST_4:
case Instruction::CONST_16:
return kSelectConst;
case Instruction::GOTO:
case Instruction::GOTO_16:
case Instruction::GOTO_32:
return kSelectGoto;
default:
return kSelectNone;
}
}
static constexpr ConditionCode kIfCcZConditionCodes[] = {
kCondEq, kCondNe, kCondLt, kCondGe, kCondGt, kCondLe
};
static_assert(arraysize(kIfCcZConditionCodes) == Instruction::IF_LEZ - Instruction::IF_EQZ + 1,
"if_ccz_ccodes_size1");
static constexpr ConditionCode ConditionCodeForIfCcZ(Instruction::Code opcode) {
return kIfCcZConditionCodes[opcode - Instruction::IF_EQZ];
}
static_assert(ConditionCodeForIfCcZ(Instruction::IF_EQZ) == kCondEq, "if_eqz ccode");
static_assert(ConditionCodeForIfCcZ(Instruction::IF_NEZ) == kCondNe, "if_nez ccode");
static_assert(ConditionCodeForIfCcZ(Instruction::IF_LTZ) == kCondLt, "if_ltz ccode");
static_assert(ConditionCodeForIfCcZ(Instruction::IF_GEZ) == kCondGe, "if_gez ccode");
static_assert(ConditionCodeForIfCcZ(Instruction::IF_GTZ) == kCondGt, "if_gtz ccode");
static_assert(ConditionCodeForIfCcZ(Instruction::IF_LEZ) == kCondLe, "if_lez ccode");
int MIRGraph::GetSSAUseCount(int s_reg) {
DCHECK_LT(static_cast<size_t>(s_reg), ssa_subscripts_.size());
return raw_use_counts_[s_reg];
}
size_t MIRGraph::GetNumBytesForSpecialTemps() const {
// This logic is written with assumption that Method* is only special temp.
DCHECK_EQ(max_available_special_compiler_temps_, 1u);
return InstructionSetPointerSize(cu_->instruction_set);
}
size_t MIRGraph::GetNumAvailableVRTemps() {
// First take into account all temps reserved for backend.
if (max_available_non_special_compiler_temps_ < reserved_temps_for_backend_) {
return 0;
}
// Calculate remaining ME temps available.
size_t remaining_me_temps = max_available_non_special_compiler_temps_ -
reserved_temps_for_backend_;
if (num_non_special_compiler_temps_ >= remaining_me_temps) {
return 0;
} else {
return remaining_me_temps - num_non_special_compiler_temps_;
}
}
// FIXME - will probably need to revisit all uses of this, as type not defined.
static const RegLocation temp_loc = {kLocCompilerTemp,
0, 1 /*defined*/, 0, 0, 0, 0, 0, 1 /*home*/,
RegStorage(), INVALID_SREG, INVALID_SREG};
CompilerTemp* MIRGraph::GetNewCompilerTemp(CompilerTempType ct_type, bool wide) {
// Once the compiler temps have been committed, new ones cannot be requested anymore.
DCHECK_EQ(compiler_temps_committed_, false);
// Make sure that reserved for BE set is sane.
DCHECK_LE(reserved_temps_for_backend_, max_available_non_special_compiler_temps_);
bool verbose = cu_->verbose;
const char* ct_type_str = nullptr;
if (verbose) {
switch (ct_type) {
case kCompilerTempBackend:
ct_type_str = "backend";
break;
case kCompilerTempSpecialMethodPtr:
ct_type_str = "method*";
break;
case kCompilerTempVR:
ct_type_str = "VR";
break;
default:
ct_type_str = "unknown";
break;
}
LOG(INFO) << "CompilerTemps: A compiler temp of type " << ct_type_str << " that is "
<< (wide ? "wide is being requested." : "not wide is being requested.");
}
CompilerTemp *compiler_temp = static_cast<CompilerTemp *>(arena_->Alloc(sizeof(CompilerTemp),
kArenaAllocRegAlloc));
// Create the type of temp requested. Special temps need special handling because
// they have a specific virtual register assignment.
if (ct_type == kCompilerTempSpecialMethodPtr) {
// This has a special location on stack which is 32-bit or 64-bit depending
// on mode. However, we don't want to overlap with non-special section
// and thus even for 64-bit, we allow only a non-wide temp to be requested.
DCHECK_EQ(wide, false);
// The vreg is always the first special temp for method ptr.
compiler_temp->v_reg = GetFirstSpecialTempVR();
CHECK(reg_location_ == nullptr);
} else if (ct_type == kCompilerTempBackend) {
requested_backend_temp_ = true;
// Make sure that we are not exceeding temps reserved for BE.
// Since VR temps cannot be requested once the BE temps are requested, we
// allow reservation of VR temps as well for BE. We
size_t available_temps = reserved_temps_for_backend_ + GetNumAvailableVRTemps();
size_t needed_temps = wide ? 2u : 1u;
if (available_temps < needed_temps) {
if (verbose) {
LOG(INFO) << "CompilerTemps: Not enough temp(s) of type " << ct_type_str
<< " are available.";
}
return nullptr;
}
// Update the remaining reserved temps since we have now used them.
// Note that the code below is actually subtracting to remove them from reserve
// once they have been claimed. It is careful to not go below zero.
reserved_temps_for_backend_ =
std::max(reserved_temps_for_backend_, needed_temps) - needed_temps;
// The new non-special compiler temp must receive a unique v_reg.
compiler_temp->v_reg = GetFirstNonSpecialTempVR() + num_non_special_compiler_temps_;
num_non_special_compiler_temps_++;
} else if (ct_type == kCompilerTempVR) {
// Once we start giving out BE temps, we don't allow anymore ME temps to be requested.
// This is done in order to prevent problems with ssa since these structures are allocated
// and managed by the ME.
DCHECK_EQ(requested_backend_temp_, false);
// There is a limit to the number of non-special temps so check to make sure it wasn't exceeded.
size_t available_temps = GetNumAvailableVRTemps();
if (available_temps <= 0 || (available_temps <= 1 && wide)) {
if (verbose) {
LOG(INFO) << "CompilerTemps: Not enough temp(s) of type " << ct_type_str
<< " are available.";
}
return nullptr;
}
// The new non-special compiler temp must receive a unique v_reg.
compiler_temp->v_reg = GetFirstNonSpecialTempVR() + num_non_special_compiler_temps_;
num_non_special_compiler_temps_++;
} else {
UNIMPLEMENTED(FATAL) << "No handling for compiler temp type " << ct_type_str << ".";
}
// We allocate an sreg as well to make developer life easier.
// However, if this is requested from an ME pass that will recalculate ssa afterwards,
// this sreg is no longer valid. The caller should be aware of this.
compiler_temp->s_reg_low = AddNewSReg(compiler_temp->v_reg);
if (verbose) {
LOG(INFO) << "CompilerTemps: New temp of type " << ct_type_str << " with v"
<< compiler_temp->v_reg << " and s" << compiler_temp->s_reg_low << " has been created.";
}
if (wide) {
// Only non-special temps are handled as wide for now.
// Note that the number of non special temps is incremented below.
DCHECK(ct_type == kCompilerTempBackend || ct_type == kCompilerTempVR);
// Ensure that the two registers are consecutive.
int ssa_reg_low = compiler_temp->s_reg_low;
int ssa_reg_high = AddNewSReg(compiler_temp->v_reg + 1);
num_non_special_compiler_temps_++;
if (verbose) {
LOG(INFO) << "CompilerTemps: The wide part of temp of type " << ct_type_str << " is v"
<< compiler_temp->v_reg + 1 << " and s" << ssa_reg_high << ".";
}
if (reg_location_ != nullptr) {
reg_location_[ssa_reg_high] = temp_loc;
reg_location_[ssa_reg_high].high_word = true;
reg_location_[ssa_reg_high].s_reg_low = ssa_reg_low;
reg_location_[ssa_reg_high].wide = true;
}
}
// If the register locations have already been allocated, add the information
// about the temp. We will not overflow because they have been initialized
// to support the maximum number of temps. For ME temps that have multiple
// ssa versions, the structures below will be expanded on the post pass cleanup.
if (reg_location_ != nullptr) {
int ssa_reg_low = compiler_temp->s_reg_low;
reg_location_[ssa_reg_low] = temp_loc;
reg_location_[ssa_reg_low].s_reg_low = ssa_reg_low;
reg_location_[ssa_reg_low].wide = wide;
}
return compiler_temp;
}
void MIRGraph::RemoveLastCompilerTemp(CompilerTempType ct_type, bool wide, CompilerTemp* temp) {
// Once the compiler temps have been committed, it's too late for any modifications.
DCHECK_EQ(compiler_temps_committed_, false);
size_t used_temps = wide ? 2u : 1u;
if (ct_type == kCompilerTempBackend) {
DCHECK(requested_backend_temp_);
// Make the temps available to backend again.
reserved_temps_for_backend_ += used_temps;
} else if (ct_type == kCompilerTempVR) {
DCHECK(!requested_backend_temp_);
} else {
UNIMPLEMENTED(FATAL) << "No handling for compiler temp type " << static_cast<int>(ct_type);
}
// Reduce the number of non-special compiler temps.
DCHECK_LE(used_temps, num_non_special_compiler_temps_);
num_non_special_compiler_temps_ -= used_temps;
// Check that this was really the last temp.
DCHECK_EQ(static_cast<size_t>(temp->v_reg),
GetFirstNonSpecialTempVR() + num_non_special_compiler_temps_);
if (cu_->verbose) {
LOG(INFO) << "Last temporary has been removed.";
}
}
static bool EvaluateBranch(Instruction::Code opcode, int32_t src1, int32_t src2) {
bool is_taken;
switch (opcode) {
case Instruction::IF_EQ: is_taken = (src1 == src2); break;
case Instruction::IF_NE: is_taken = (src1 != src2); break;
case Instruction::IF_LT: is_taken = (src1 < src2); break;
case Instruction::IF_GE: is_taken = (src1 >= src2); break;
case Instruction::IF_GT: is_taken = (src1 > src2); break;
case Instruction::IF_LE: is_taken = (src1 <= src2); break;
case Instruction::IF_EQZ: is_taken = (src1 == 0); break;
case Instruction::IF_NEZ: is_taken = (src1 != 0); break;
case Instruction::IF_LTZ: is_taken = (src1 < 0); break;
case Instruction::IF_GEZ: is_taken = (src1 >= 0); break;
case Instruction::IF_GTZ: is_taken = (src1 > 0); break;
case Instruction::IF_LEZ: is_taken = (src1 <= 0); break;
default:
LOG(FATAL) << "Unexpected opcode " << opcode;
UNREACHABLE();
}
return is_taken;
}
/* Do some MIR-level extended basic block optimizations */
bool MIRGraph::BasicBlockOpt(BasicBlock* bb) {
if (bb->block_type == kDead) {
return true;
}
// Currently multiply-accumulate backend supports are only available on arm32 and arm64.
if (cu_->instruction_set == kArm64 || cu_->instruction_set == kThumb2) {
MultiplyAddOpt(bb);
}
bool use_lvn = bb->use_lvn && (cu_->disable_opt & (1u << kLocalValueNumbering)) == 0u;
std::unique_ptr<ScopedArenaAllocator> allocator;
std::unique_ptr<GlobalValueNumbering> global_valnum;
std::unique_ptr<LocalValueNumbering> local_valnum;
if (use_lvn) {
allocator.reset(ScopedArenaAllocator::Create(&cu_->arena_stack));
global_valnum.reset(new (allocator.get()) GlobalValueNumbering(cu_, allocator.get(),
GlobalValueNumbering::kModeLvn));
local_valnum.reset(new (allocator.get()) LocalValueNumbering(global_valnum.get(), bb->id,
allocator.get()));
}
while (bb != nullptr) {
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
// TUNING: use the returned value number for CSE.
if (use_lvn) {
local_valnum->GetValueNumber(mir);
}
// Look for interesting opcodes, skip otherwise
Instruction::Code opcode = mir->dalvikInsn.opcode;
switch (opcode) {
case Instruction::IF_EQ:
case Instruction::IF_NE:
case Instruction::IF_LT:
case Instruction::IF_GE:
case Instruction::IF_GT:
case Instruction::IF_LE:
if (!IsConst(mir->ssa_rep->uses[1])) {
break;
}
FALLTHROUGH_INTENDED;
case Instruction::IF_EQZ:
case Instruction::IF_NEZ:
case Instruction::IF_LTZ:
case Instruction::IF_GEZ:
case Instruction::IF_GTZ:
case Instruction::IF_LEZ:
// Result known at compile time?
if (IsConst(mir->ssa_rep->uses[0])) {
int32_t rhs = (mir->ssa_rep->num_uses == 2) ? ConstantValue(mir->ssa_rep->uses[1]) : 0;
bool is_taken = EvaluateBranch(opcode, ConstantValue(mir->ssa_rep->uses[0]), rhs);
BasicBlockId edge_to_kill = is_taken ? bb->fall_through : bb->taken;
if (is_taken) {
// Replace with GOTO.
bb->fall_through = NullBasicBlockId;
mir->dalvikInsn.opcode = Instruction::GOTO;
mir->dalvikInsn.vA =
IsInstructionIfCc(opcode) ? mir->dalvikInsn.vC : mir->dalvikInsn.vB;
} else {
// Make NOP.
bb->taken = NullBasicBlockId;
mir->dalvikInsn.opcode = static_cast<Instruction::Code>(kMirOpNop);
}
mir->ssa_rep->num_uses = 0;
BasicBlock* successor_to_unlink = GetBasicBlock(edge_to_kill);
successor_to_unlink->ErasePredecessor(bb->id);
// We have changed the graph structure.
dfs_orders_up_to_date_ = false;
domination_up_to_date_ = false;
topological_order_up_to_date_ = false;
// Keep MIR SSA rep, the worst that can happen is a Phi with just 1 input.
}
break;
case Instruction::CMPL_FLOAT:
case Instruction::CMPL_DOUBLE:
case Instruction::CMPG_FLOAT:
case Instruction::CMPG_DOUBLE:
case Instruction::CMP_LONG:
if ((cu_->disable_opt & (1 << kBranchFusing)) != 0) {
// Bitcode doesn't allow this optimization.
break;
}
if (mir->next != nullptr) {
MIR* mir_next = mir->next;
// Make sure result of cmp is used by next insn and nowhere else
if (IsInstructionIfCcZ(mir_next->dalvikInsn.opcode) &&
(mir->ssa_rep->defs[0] == mir_next->ssa_rep->uses[0]) &&
(GetSSAUseCount(mir->ssa_rep->defs[0]) == 1)) {
mir_next->meta.ccode = ConditionCodeForIfCcZ(mir_next->dalvikInsn.opcode);
switch (opcode) {
case Instruction::CMPL_FLOAT:
mir_next->dalvikInsn.opcode =
static_cast<Instruction::Code>(kMirOpFusedCmplFloat);
break;
case Instruction::CMPL_DOUBLE:
mir_next->dalvikInsn.opcode =
static_cast<Instruction::Code>(kMirOpFusedCmplDouble);
break;
case Instruction::CMPG_FLOAT:
mir_next->dalvikInsn.opcode =
static_cast<Instruction::Code>(kMirOpFusedCmpgFloat);
break;
case Instruction::CMPG_DOUBLE:
mir_next->dalvikInsn.opcode =
static_cast<Instruction::Code>(kMirOpFusedCmpgDouble);
break;
case Instruction::CMP_LONG:
mir_next->dalvikInsn.opcode =
static_cast<Instruction::Code>(kMirOpFusedCmpLong);
break;
default: LOG(ERROR) << "Unexpected opcode: " << opcode;
}
mir->dalvikInsn.opcode = static_cast<Instruction::Code>(kMirOpNop);
// Clear use count of temp VR.
use_counts_[mir->ssa_rep->defs[0]] = 0;
raw_use_counts_[mir->ssa_rep->defs[0]] = 0;
// Copy the SSA information that is relevant.
mir_next->ssa_rep->num_uses = mir->ssa_rep->num_uses;
mir_next->ssa_rep->uses = mir->ssa_rep->uses;
mir_next->ssa_rep->num_defs = 0;
mir->ssa_rep->num_uses = 0;
mir->ssa_rep->num_defs = 0;
// Copy in the decoded instruction information for potential SSA re-creation.
mir_next->dalvikInsn.vA = mir->dalvikInsn.vB;
mir_next->dalvikInsn.vB = mir->dalvikInsn.vC;
}
}
break;
default:
break;
}
// Is this the select pattern?
// TODO: flesh out support for Mips. NOTE: llvm's select op doesn't quite work here.
// TUNING: expand to support IF_xx compare & branches
if ((cu_->instruction_set == kArm64 || cu_->instruction_set == kThumb2 ||
cu_->instruction_set == kX86 || cu_->instruction_set == kX86_64) &&
IsInstructionIfCcZ(mir->dalvikInsn.opcode)) {
BasicBlock* ft = GetBasicBlock(bb->fall_through);
DCHECK(ft != nullptr);
BasicBlock* ft_ft = GetBasicBlock(ft->fall_through);
BasicBlock* ft_tk = GetBasicBlock(ft->taken);
BasicBlock* tk = GetBasicBlock(bb->taken);
DCHECK(tk != nullptr);
BasicBlock* tk_ft = GetBasicBlock(tk->fall_through);
BasicBlock* tk_tk = GetBasicBlock(tk->taken);
/*
* In the select pattern, the taken edge goes to a block that unconditionally
* transfers to the rejoin block and the fall_though edge goes to a block that
* unconditionally falls through to the rejoin block.
*/
if ((tk_ft == nullptr) && (ft_tk == nullptr) && (tk_tk == ft_ft) &&
(Predecessors(tk) == 1) && (Predecessors(ft) == 1)) {
/*
* Okay - we have the basic diamond shape.
*/
// TODO: Add logic for LONG.
// Are the block bodies something we can handle?
if ((ft->first_mir_insn == ft->last_mir_insn) &&
(tk->first_mir_insn != tk->last_mir_insn) &&
(tk->first_mir_insn->next == tk->last_mir_insn) &&
((SelectKind(ft->first_mir_insn) == kSelectMove) ||
(SelectKind(ft->first_mir_insn) == kSelectConst)) &&
(SelectKind(ft->first_mir_insn) == SelectKind(tk->first_mir_insn)) &&
(SelectKind(tk->last_mir_insn) == kSelectGoto)) {
// Almost there. Are the instructions targeting the same vreg?
MIR* if_true = tk->first_mir_insn;
MIR* if_false = ft->first_mir_insn;
// It's possible that the target of the select isn't used - skip those (rare) cases.
MIR* phi = FindPhi(tk_tk, if_true->ssa_rep->defs[0]);
if ((phi != nullptr) && (if_true->dalvikInsn.vA == if_false->dalvikInsn.vA)) {
/*
* We'll convert the IF_EQZ/IF_NEZ to a SELECT. We need to find the
* Phi node in the merge block and delete it (while using the SSA name
* of the merge as the target of the SELECT. Delete both taken and
* fallthrough blocks, and set fallthrough to merge block.
* NOTE: not updating other dataflow info (no longer used at this point).
* If this changes, need to update i_dom, etc. here (and in CombineBlocks).
*/
mir->meta.ccode = ConditionCodeForIfCcZ(mir->dalvikInsn.opcode);
mir->dalvikInsn.opcode = static_cast<Instruction::Code>(kMirOpSelect);
bool const_form = (SelectKind(if_true) == kSelectConst);
if ((SelectKind(if_true) == kSelectMove)) {
if (IsConst(if_true->ssa_rep->uses[0]) &&
IsConst(if_false->ssa_rep->uses[0])) {
const_form = true;
if_true->dalvikInsn.vB = ConstantValue(if_true->ssa_rep->uses[0]);
if_false->dalvikInsn.vB = ConstantValue(if_false->ssa_rep->uses[0]);
}
}
if (const_form) {
/*
* TODO: If both constants are the same value, then instead of generating
* a select, we should simply generate a const bytecode. This should be
* considered after inlining which can lead to CFG of this form.
*/
// "true" set val in vB
mir->dalvikInsn.vB = if_true->dalvikInsn.vB;
// "false" set val in vC
mir->dalvikInsn.vC = if_false->dalvikInsn.vB;
} else {
DCHECK_EQ(SelectKind(if_true), kSelectMove);
DCHECK_EQ(SelectKind(if_false), kSelectMove);
int32_t* src_ssa = arena_->AllocArray<int32_t>(3, kArenaAllocDFInfo);
src_ssa[0] = mir->ssa_rep->uses[0];
src_ssa[1] = if_true->ssa_rep->uses[0];
src_ssa[2] = if_false->ssa_rep->uses[0];
mir->ssa_rep->uses = src_ssa;
mir->ssa_rep->num_uses = 3;
}
AllocateSSADefData(mir, 1);
/*
* There is usually a Phi node in the join block for our two cases. If the
* Phi node only contains our two cases as input, we will use the result
* SSA name of the Phi node as our select result and delete the Phi. If
* the Phi node has more than two operands, we will arbitrarily use the SSA
* name of the "false" path, delete the SSA name of the "true" path from the
* Phi node (and fix up the incoming arc list).
*/
if (phi->ssa_rep->num_uses == 2) {
mir->ssa_rep->defs[0] = phi->ssa_rep->defs[0];
// Rather than changing the Phi to kMirOpNop, remove it completely.
// This avoids leaving other Phis after kMirOpNop (i.e. a non-Phi) insn.
tk_tk->RemoveMIR(phi);
int dead_false_def = if_false->ssa_rep->defs[0];
raw_use_counts_[dead_false_def] = use_counts_[dead_false_def] = 0;
} else {
int live_def = if_false->ssa_rep->defs[0];
mir->ssa_rep->defs[0] = live_def;
}
int dead_true_def = if_true->ssa_rep->defs[0];
raw_use_counts_[dead_true_def] = use_counts_[dead_true_def] = 0;
// Update ending vreg->sreg map for GC maps generation.
int def_vreg = SRegToVReg(mir->ssa_rep->defs[0]);
bb->data_flow_info->vreg_to_ssa_map_exit[def_vreg] = mir->ssa_rep->defs[0];
// We want to remove ft and tk and link bb directly to ft_ft. First, we need
// to update all Phi inputs correctly with UpdatePredecessor(ft->id, bb->id)
// since the live_def above comes from ft->first_mir_insn (if_false).
DCHECK(if_false == ft->first_mir_insn);
ft_ft->UpdatePredecessor(ft->id, bb->id);
// Correct the rest of the links between bb, ft and ft_ft.
ft->ErasePredecessor(bb->id);
ft->fall_through = NullBasicBlockId;
bb->fall_through = ft_ft->id;
// Now we can kill tk and ft.
tk->Kill(this);
ft->Kill(this);
// NOTE: DFS order, domination info and topological order are still usable
// despite the newly dead blocks.
}
}
}
}
}
bb = ((cu_->disable_opt & (1 << kSuppressExceptionEdges)) != 0) ? NextDominatedBlock(bb) :
nullptr;
}
if (use_lvn && UNLIKELY(!global_valnum->Good())) {
LOG(WARNING) << "LVN overflow in " << PrettyMethod(cu_->method_idx, *cu_->dex_file);
}
return true;
}
/* Collect stats on number of checks removed */
void MIRGraph::CountChecks(class BasicBlock* bb) {
if (bb->data_flow_info != nullptr) {
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
if (mir->ssa_rep == nullptr) {
continue;
}
uint64_t df_attributes = GetDataFlowAttributes(mir);
if (df_attributes & DF_HAS_NULL_CHKS) {
checkstats_->null_checks++;
if (mir->optimization_flags & MIR_IGNORE_NULL_CHECK) {
checkstats_->null_checks_eliminated++;
}
}
if (df_attributes & DF_HAS_RANGE_CHKS) {
checkstats_->range_checks++;
if (mir->optimization_flags & MIR_IGNORE_RANGE_CHECK) {
checkstats_->range_checks_eliminated++;
}
}
}
}
}
/* Try to make common case the fallthrough path. */
bool MIRGraph::LayoutBlocks(BasicBlock* bb) {
// TODO: For now, just looking for direct throws. Consider generalizing for profile feedback.
if (!bb->explicit_throw) {
return false;
}
// If we visited it, we are done.
if (bb->visited) {
return false;
}
bb->visited = true;
BasicBlock* walker = bb;
while (true) {
// Check termination conditions.
if ((walker->block_type == kEntryBlock) || (Predecessors(walker) != 1)) {
break;
}
DCHECK(!walker->predecessors.empty());
BasicBlock* prev = GetBasicBlock(walker->predecessors[0]);
// If we visited the predecessor, we are done.
if (prev->visited) {
return false;
}
prev->visited = true;
if (prev->conditional_branch) {
if (GetBasicBlock(prev->fall_through) == walker) {
// Already done - return.
break;
}
DCHECK_EQ(walker, GetBasicBlock(prev->taken));
// Got one. Flip it and exit.
Instruction::Code opcode = prev->last_mir_insn->dalvikInsn.opcode;
switch (opcode) {
case Instruction::IF_EQ: opcode = Instruction::IF_NE; break;
case Instruction::IF_NE: opcode = Instruction::IF_EQ; break;
case Instruction::IF_LT: opcode = Instruction::IF_GE; break;
case Instruction::IF_GE: opcode = Instruction::IF_LT; break;
case Instruction::IF_GT: opcode = Instruction::IF_LE; break;
case Instruction::IF_LE: opcode = Instruction::IF_GT; break;
case Instruction::IF_EQZ: opcode = Instruction::IF_NEZ; break;
case Instruction::IF_NEZ: opcode = Instruction::IF_EQZ; break;
case Instruction::IF_LTZ: opcode = Instruction::IF_GEZ; break;
case Instruction::IF_GEZ: opcode = Instruction::IF_LTZ; break;
case Instruction::IF_GTZ: opcode = Instruction::IF_LEZ; break;
case Instruction::IF_LEZ: opcode = Instruction::IF_GTZ; break;
default: LOG(FATAL) << "Unexpected opcode " << opcode;
}
prev->last_mir_insn->dalvikInsn.opcode = opcode;
BasicBlockId t_bb = prev->taken;
prev->taken = prev->fall_through;
prev->fall_through = t_bb;
break;
}
walker = prev;
}
return false;
}
/* Combine any basic blocks terminated by instructions that we now know can't throw */
void MIRGraph::CombineBlocks(class BasicBlock* bb) {
// Loop here to allow combining a sequence of blocks
while ((bb->block_type == kDalvikByteCode) &&
(bb->last_mir_insn != nullptr) &&
(static_cast<int>(bb->last_mir_insn->dalvikInsn.opcode) == kMirOpCheck)) {
MIR* mir = bb->last_mir_insn;
DCHECK(bb->first_mir_insn != nullptr);
// Get the paired insn and check if it can still throw.
MIR* throw_insn = mir->meta.throw_insn;
if (CanThrow(throw_insn)) {
break;
}
// OK - got one. Combine
BasicBlock* bb_next = GetBasicBlock(bb->fall_through);
DCHECK(!bb_next->catch_entry);
DCHECK_EQ(bb_next->predecessors.size(), 1u);
// Now move instructions from bb_next to bb. Start off with doing a sanity check
// that kMirOpCheck's throw instruction is first one in the bb_next.
DCHECK_EQ(bb_next->first_mir_insn, throw_insn);
// Now move all instructions (throw instruction to last one) from bb_next to bb.
MIR* last_to_move = bb_next->last_mir_insn;
bb_next->RemoveMIRList(throw_insn, last_to_move);
bb->InsertMIRListAfter(bb->last_mir_insn, throw_insn, last_to_move);
// The kMirOpCheck instruction is not needed anymore.
mir->dalvikInsn.opcode = static_cast<Instruction::Code>(kMirOpNop);
bb->RemoveMIR(mir);
// Before we overwrite successors, remove their predecessor links to bb.
bb_next->ErasePredecessor(bb->id);
if (bb->taken != NullBasicBlockId) {
DCHECK_EQ(bb->successor_block_list_type, kNotUsed);
BasicBlock* bb_taken = GetBasicBlock(bb->taken);
// bb->taken will be overwritten below.
DCHECK_EQ(bb_taken->block_type, kExceptionHandling);
DCHECK_EQ(bb_taken->predecessors.size(), 1u);
DCHECK_EQ(bb_taken->predecessors[0], bb->id);
bb_taken->predecessors.clear();
bb_taken->block_type = kDead;
DCHECK(bb_taken->data_flow_info == nullptr);
} else {
DCHECK_EQ(bb->successor_block_list_type, kCatch);
for (SuccessorBlockInfo* succ_info : bb->successor_blocks) {
if (succ_info->block != NullBasicBlockId) {
BasicBlock* succ_bb = GetBasicBlock(succ_info->block);
DCHECK(succ_bb->catch_entry);
succ_bb->ErasePredecessor(bb->id);
}
}
}
// Use the successor info from the next block
bb->successor_block_list_type = bb_next->successor_block_list_type;
bb->successor_blocks.swap(bb_next->successor_blocks); // Swap instead of copying.
bb_next->successor_block_list_type = kNotUsed;
// Use the ending block linkage from the next block
bb->fall_through = bb_next->fall_through;
bb_next->fall_through = NullBasicBlockId;
bb->taken = bb_next->taken;
bb_next->taken = NullBasicBlockId;
/*
* If lower-half of pair of blocks to combine contained
* a return or a conditional branch or an explicit throw,
* move the flag to the newly combined block.
*/
bb->terminated_by_return = bb_next->terminated_by_return;
bb->conditional_branch = bb_next->conditional_branch;
bb->explicit_throw = bb_next->explicit_throw;
// Merge the use_lvn flag.
bb->use_lvn |= bb_next->use_lvn;
// Kill the unused block.
bb_next->data_flow_info = nullptr;
/*
* NOTE: we aren't updating all dataflow info here. Should either make sure this pass
* happens after uses of i_dominated, dom_frontier or update the dataflow info here.
* NOTE: GVN uses bb->data_flow_info->live_in_v which is unaffected by the block merge.
*/
// Kill bb_next and remap now-dead id to parent.
bb_next->block_type = kDead;
bb_next->data_flow_info = nullptr; // Must be null for dead blocks. (Relied on by the GVN.)
block_id_map_.Overwrite(bb_next->id, bb->id);
// Update predecessors in children.
ChildBlockIterator iter(bb, this);
for (BasicBlock* child = iter.Next(); child != nullptr; child = iter.Next()) {
child->UpdatePredecessor(bb_next->id, bb->id);
}
// DFS orders, domination and topological order are not up to date anymore.
dfs_orders_up_to_date_ = false;
domination_up_to_date_ = false;
topological_order_up_to_date_ = false;
// Now, loop back and see if we can keep going
}
}
bool MIRGraph::EliminateNullChecksGate() {
if ((cu_->disable_opt & (1 << kNullCheckElimination)) != 0 ||
(merged_df_flags_ & DF_HAS_NULL_CHKS) == 0) {
return false;
}
DCHECK(temp_scoped_alloc_.get() == nullptr);
temp_scoped_alloc_.reset(ScopedArenaAllocator::Create(&cu_->arena_stack));
temp_.nce.num_vregs = GetNumOfCodeAndTempVRs();
temp_.nce.work_vregs_to_check = new (temp_scoped_alloc_.get()) ArenaBitVector(
temp_scoped_alloc_.get(), temp_.nce.num_vregs, false, kBitMapNullCheck);
temp_.nce.ending_vregs_to_check_matrix =
temp_scoped_alloc_->AllocArray<ArenaBitVector*>(GetNumBlocks(), kArenaAllocMisc);
std::fill_n(temp_.nce.ending_vregs_to_check_matrix, GetNumBlocks(), nullptr);
// reset MIR_MARK
AllNodesIterator iter(this);
for (BasicBlock* bb = iter.Next(); bb != nullptr; bb = iter.Next()) {
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
mir->optimization_flags &= ~MIR_MARK;
}
}
return true;
}
/*
* Eliminate unnecessary null checks for a basic block.
*/
bool MIRGraph::EliminateNullChecks(BasicBlock* bb) {
if (bb->block_type != kDalvikByteCode && bb->block_type != kEntryBlock) {
// Ignore the kExitBlock as well.
DCHECK(bb->first_mir_insn == nullptr);
return false;
}
ArenaBitVector* vregs_to_check = temp_.nce.work_vregs_to_check;
/*
* Set initial state. Catch blocks don't need any special treatment.
*/
if (bb->block_type == kEntryBlock) {
vregs_to_check->ClearAllBits();
// Assume all ins are objects.
for (uint16_t in_reg = GetFirstInVR();
in_reg < GetNumOfCodeVRs(); in_reg++) {
vregs_to_check->SetBit(in_reg);
}
if ((cu_->access_flags & kAccStatic) == 0) {
// If non-static method, mark "this" as non-null.
int this_reg = GetFirstInVR();
vregs_to_check->ClearBit(this_reg);
}
} else {
DCHECK_EQ(bb->block_type, kDalvikByteCode);
// Starting state is union of all incoming arcs.
bool copied_first = false;
for (BasicBlockId pred_id : bb->predecessors) {
if (temp_.nce.ending_vregs_to_check_matrix[pred_id] == nullptr) {
continue;
}
BasicBlock* pred_bb = GetBasicBlock(pred_id);
DCHECK(pred_bb != nullptr);
MIR* null_check_insn = nullptr;
// Check to see if predecessor had an explicit null-check.
if (pred_bb->BranchesToSuccessorOnlyIfNotZero(bb->id)) {
// Remember the null check insn if there's no other predecessor requiring null check.
if (!copied_first || !vregs_to_check->IsBitSet(pred_bb->last_mir_insn->dalvikInsn.vA)) {
null_check_insn = pred_bb->last_mir_insn;
DCHECK(null_check_insn != nullptr);
}
}
if (!copied_first) {
copied_first = true;
vregs_to_check->Copy(temp_.nce.ending_vregs_to_check_matrix[pred_id]);
} else {
vregs_to_check->Union(temp_.nce.ending_vregs_to_check_matrix[pred_id]);
}
if (null_check_insn != nullptr) {
vregs_to_check->ClearBit(null_check_insn->dalvikInsn.vA);
}
}
DCHECK(copied_first); // At least one predecessor must have been processed before this bb.
}
// At this point, vregs_to_check shows which sregs have an object definition with
// no intervening uses.
// Walk through the instruction in the block, updating as necessary
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
uint64_t df_attributes = GetDataFlowAttributes(mir);
if ((df_attributes & DF_NULL_TRANSFER_N) != 0u) {
// The algorithm was written in a phi agnostic way.
continue;
}
// Might need a null check?
if (df_attributes & DF_HAS_NULL_CHKS) {
int src_vreg;
if (df_attributes & DF_NULL_CHK_OUT0) {
DCHECK_NE(df_attributes & DF_IS_INVOKE, 0u);
src_vreg = mir->dalvikInsn.vC;
} else if (df_attributes & DF_NULL_CHK_B) {
DCHECK_NE(df_attributes & DF_REF_B, 0u);
src_vreg = mir->dalvikInsn.vB;
} else {
DCHECK_NE(df_attributes & DF_NULL_CHK_A, 0u);
DCHECK_NE(df_attributes & DF_REF_A, 0u);
src_vreg = mir->dalvikInsn.vA;
}
if (!vregs_to_check->IsBitSet(src_vreg)) {
// Eliminate the null check.
mir->optimization_flags |= MIR_MARK;
} else {
// Do the null check.
mir->optimization_flags &= ~MIR_MARK;
// Mark src_vreg as null-checked.
vregs_to_check->ClearBit(src_vreg);
}
}
if ((df_attributes & DF_A_WIDE) ||
(df_attributes & (DF_REF_A | DF_SETS_CONST | DF_NULL_TRANSFER)) == 0) {
continue;
}
/*
* First, mark all object definitions as requiring null check.
* Note: we can't tell if a CONST definition might be used as an object, so treat
* them all as object definitions.
*/
if ((df_attributes & (DF_DA | DF_REF_A)) == (DF_DA | DF_REF_A) ||
(df_attributes & DF_SETS_CONST)) {
vregs_to_check->SetBit(mir->dalvikInsn.vA);
}
// Then, remove mark from all object definitions we know are non-null.
if (df_attributes & DF_NON_NULL_DST) {
// Mark target of NEW* as non-null
DCHECK_NE(df_attributes & DF_REF_A, 0u);
vregs_to_check->ClearBit(mir->dalvikInsn.vA);
}
// Mark non-null returns from invoke-style NEW*
if (df_attributes & DF_NON_NULL_RET) {
MIR* next_mir = mir->next;
// Next should be an MOVE_RESULT_OBJECT
if (UNLIKELY(next_mir == nullptr)) {
// The MethodVerifier makes sure there's no MOVE_RESULT at the catch entry or branch
// target, so the MOVE_RESULT cannot be broken away into another block.
LOG(WARNING) << "Unexpected end of block following new";
} else if (UNLIKELY(next_mir->dalvikInsn.opcode != Instruction::MOVE_RESULT_OBJECT)) {
LOG(WARNING) << "Unexpected opcode following new: " << next_mir->dalvikInsn.opcode;
} else {
// Mark as null checked.
vregs_to_check->ClearBit(next_mir->dalvikInsn.vA);
}
}
// Propagate null check state on register copies.
if (df_attributes & DF_NULL_TRANSFER_0) {
DCHECK_EQ(df_attributes | ~(DF_DA | DF_REF_A | DF_UB | DF_REF_B), static_cast<uint64_t>(-1));
if (vregs_to_check->IsBitSet(mir->dalvikInsn.vB)) {
vregs_to_check->SetBit(mir->dalvikInsn.vA);
} else {
vregs_to_check->ClearBit(mir->dalvikInsn.vA);
}
}
}
// Did anything change?
bool nce_changed = false;
ArenaBitVector* old_ending_ssa_regs_to_check = temp_.nce.ending_vregs_to_check_matrix[bb->id];
if (old_ending_ssa_regs_to_check == nullptr) {
DCHECK(temp_scoped_alloc_.get() != nullptr);
nce_changed = vregs_to_check->GetHighestBitSet() != -1;
temp_.nce.ending_vregs_to_check_matrix[bb->id] = vregs_to_check;
// Create a new vregs_to_check for next BB.
temp_.nce.work_vregs_to_check = new (temp_scoped_alloc_.get()) ArenaBitVector(
temp_scoped_alloc_.get(), temp_.nce.num_vregs, false, kBitMapNullCheck);
} else if (!vregs_to_check->SameBitsSet(old_ending_ssa_regs_to_check)) {
nce_changed = true;
temp_.nce.ending_vregs_to_check_matrix[bb->id] = vregs_to_check;
temp_.nce.work_vregs_to_check = old_ending_ssa_regs_to_check; // Reuse for next BB.
}
return nce_changed;
}
void MIRGraph::EliminateNullChecksEnd() {
// Clean up temporaries.
temp_.nce.num_vregs = 0u;
temp_.nce.work_vregs_to_check = nullptr;
temp_.nce.ending_vregs_to_check_matrix = nullptr;
DCHECK(temp_scoped_alloc_.get() != nullptr);
temp_scoped_alloc_.reset();
// converge MIR_MARK with MIR_IGNORE_NULL_CHECK
AllNodesIterator iter(this);
for (BasicBlock* bb = iter.Next(); bb != nullptr; bb = iter.Next()) {
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
constexpr int kMarkToIgnoreNullCheckShift = kMIRMark - kMIRIgnoreNullCheck;
static_assert(kMarkToIgnoreNullCheckShift > 0, "Not a valid right-shift");
uint16_t mirMarkAdjustedToIgnoreNullCheck =
(mir->optimization_flags & MIR_MARK) >> kMarkToIgnoreNullCheckShift;
mir->optimization_flags |= mirMarkAdjustedToIgnoreNullCheck;
}
}
}
void MIRGraph::InferTypesStart() {
DCHECK(temp_scoped_alloc_ != nullptr);
temp_.ssa.ti = new (temp_scoped_alloc_.get()) TypeInference(this, temp_scoped_alloc_.get());
}
/*
* Perform type and size inference for a basic block.
*/
bool MIRGraph::InferTypes(BasicBlock* bb) {
if (bb->data_flow_info == nullptr) return false;
DCHECK(temp_.ssa.ti != nullptr);
return temp_.ssa.ti->Apply(bb);
}
void MIRGraph::InferTypesEnd() {
DCHECK(temp_.ssa.ti != nullptr);
temp_.ssa.ti->Finish();
delete temp_.ssa.ti;
temp_.ssa.ti = nullptr;
}
bool MIRGraph::EliminateClassInitChecksGate() {
if ((cu_->disable_opt & (1 << kClassInitCheckElimination)) != 0 ||
(merged_df_flags_ & DF_CLINIT) == 0) {
return false;
}
DCHECK(temp_scoped_alloc_.get() == nullptr);
temp_scoped_alloc_.reset(ScopedArenaAllocator::Create(&cu_->arena_stack));
// Each insn we use here has at least 2 code units, offset/2 will be a unique index.
const size_t end = (GetNumDalvikInsns() + 1u) / 2u;
temp_.cice.indexes = temp_scoped_alloc_->AllocArray<uint16_t>(end, kArenaAllocGrowableArray);
std::fill_n(temp_.cice.indexes, end, 0xffffu);
uint32_t unique_class_count = 0u;
{
// Get unique_class_count and store indexes in temp_insn_data_ using a map on a nested
// ScopedArenaAllocator.
// Embed the map value in the entry to save space.
struct MapEntry {
// Map key: the class identified by the declaring dex file and type index.
const DexFile* declaring_dex_file;
uint16_t declaring_class_idx;
// Map value: index into bit vectors of classes requiring initialization checks.
uint16_t index;
};
struct MapEntryComparator {
bool operator()(const MapEntry& lhs, const MapEntry& rhs) const {
if (lhs.declaring_class_idx != rhs.declaring_class_idx) {
return lhs.declaring_class_idx < rhs.declaring_class_idx;
}
return lhs.declaring_dex_file < rhs.declaring_dex_file;
}
};
ScopedArenaAllocator allocator(&cu_->arena_stack);
ScopedArenaSet<MapEntry, MapEntryComparator> class_to_index_map(MapEntryComparator(),
allocator.Adapter());
// First, find all SGET/SPUTs that may need class initialization checks, record INVOKE_STATICs.
AllNodesIterator iter(this);
for (BasicBlock* bb = iter.Next(); bb != nullptr; bb = iter.Next()) {
if (bb->block_type == kDalvikByteCode) {
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
if (IsInstructionSGetOrSPut(mir->dalvikInsn.opcode)) {
const MirSFieldLoweringInfo& field_info = GetSFieldLoweringInfo(mir);
if (!field_info.IsReferrersClass()) {
DCHECK_LT(class_to_index_map.size(), 0xffffu);
MapEntry entry = {
// Treat unresolved fields as if each had its own class.
field_info.IsResolved() ? field_info.DeclaringDexFile()
: nullptr,
field_info.IsResolved() ? field_info.DeclaringClassIndex()
: field_info.FieldIndex(),
static_cast<uint16_t>(class_to_index_map.size())
};
uint16_t index = class_to_index_map.insert(entry).first->index;
// Using offset/2 for index into temp_.cice.indexes.
temp_.cice.indexes[mir->offset / 2u] = index;
}
} else if (IsInstructionInvokeStatic(mir->dalvikInsn.opcode)) {
const MirMethodLoweringInfo& method_info = GetMethodLoweringInfo(mir);
DCHECK(method_info.IsStatic());
if (method_info.FastPath() && !method_info.IsReferrersClass()) {
MapEntry entry = {
method_info.DeclaringDexFile(),
method_info.DeclaringClassIndex(),
static_cast<uint16_t>(class_to_index_map.size())
};
uint16_t index = class_to_index_map.insert(entry).first->index;
// Using offset/2 for index into temp_.cice.indexes.
temp_.cice.indexes[mir->offset / 2u] = index;
}
}
}
}
}
unique_class_count = static_cast<uint32_t>(class_to_index_map.size());
}
if (unique_class_count == 0u) {
// All SGET/SPUTs refer to initialized classes. Nothing to do.
temp_.cice.indexes = nullptr;
temp_scoped_alloc_.reset();
return false;
}
// 2 bits for each class: is class initialized, is class in dex cache.
temp_.cice.num_class_bits = 2u * unique_class_count;
temp_.cice.work_classes_to_check = new (temp_scoped_alloc_.get()) ArenaBitVector(
temp_scoped_alloc_.get(), temp_.cice.num_class_bits, false, kBitMapClInitCheck);
temp_.cice.ending_classes_to_check_matrix =
temp_scoped_alloc_->AllocArray<ArenaBitVector*>(GetNumBlocks(), kArenaAllocMisc);
std::fill_n(temp_.cice.ending_classes_to_check_matrix, GetNumBlocks(), nullptr);
DCHECK_GT(temp_.cice.num_class_bits, 0u);
return true;
}
/*
* Eliminate unnecessary class initialization checks for a basic block.
*/
bool MIRGraph::EliminateClassInitChecks(BasicBlock* bb) {
DCHECK_EQ((cu_->disable_opt & (1 << kClassInitCheckElimination)), 0u);
if (bb->block_type != kDalvikByteCode && bb->block_type != kEntryBlock) {
// Ignore the kExitBlock as well.
DCHECK(bb->first_mir_insn == nullptr);
return false;
}
/*
* Set initial state. Catch blocks don't need any special treatment.
*/
ArenaBitVector* classes_to_check = temp_.cice.work_classes_to_check;
DCHECK(classes_to_check != nullptr);
if (bb->block_type == kEntryBlock) {
classes_to_check->SetInitialBits(temp_.cice.num_class_bits);
} else {
// Starting state is union of all incoming arcs.
bool copied_first = false;
for (BasicBlockId pred_id : bb->predecessors) {
if (temp_.cice.ending_classes_to_check_matrix[pred_id] == nullptr) {
continue;
}
if (!copied_first) {
copied_first = true;
classes_to_check->Copy(temp_.cice.ending_classes_to_check_matrix[pred_id]);
} else {
classes_to_check->Union(temp_.cice.ending_classes_to_check_matrix[pred_id]);
}
}
DCHECK(copied_first); // At least one predecessor must have been processed before this bb.
}
// At this point, classes_to_check shows which classes need clinit checks.
// Walk through the instruction in the block, updating as necessary
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
uint16_t index = temp_.cice.indexes[mir->offset / 2u];
if (index != 0xffffu) {
bool check_initialization = false;
bool check_dex_cache = false;
// NOTE: index != 0xffff does not guarantee that this is an SGET/SPUT/INVOKE_STATIC.
// Dex instructions with width 1 can have the same offset/2.
if (IsInstructionSGetOrSPut(mir->dalvikInsn.opcode)) {
check_initialization = true;
check_dex_cache = true;
} else if (IsInstructionInvokeStatic(mir->dalvikInsn.opcode)) {
check_initialization = true;
// NOTE: INVOKE_STATIC doesn't guarantee that the type will be in the dex cache.
}
if (check_dex_cache) {
uint32_t check_dex_cache_index = 2u * index + 1u;
if (!classes_to_check->IsBitSet(check_dex_cache_index)) {
// Eliminate the class init check.
mir->optimization_flags |= MIR_CLASS_IS_IN_DEX_CACHE;
} else {
// Do the class init check.
mir->optimization_flags &= ~MIR_CLASS_IS_IN_DEX_CACHE;
}
classes_to_check->ClearBit(check_dex_cache_index);
}
if (check_initialization) {
uint32_t check_clinit_index = 2u * index;
if (!classes_to_check->IsBitSet(check_clinit_index)) {
// Eliminate the class init check.
mir->optimization_flags |= MIR_CLASS_IS_INITIALIZED;
} else {
// Do the class init check.
mir->optimization_flags &= ~MIR_CLASS_IS_INITIALIZED;
}
// Mark the class as initialized.
classes_to_check->ClearBit(check_clinit_index);
}
}
}
// Did anything change?
bool changed = false;
ArenaBitVector* old_ending_classes_to_check = temp_.cice.ending_classes_to_check_matrix[bb->id];
if (old_ending_classes_to_check == nullptr) {
DCHECK(temp_scoped_alloc_.get() != nullptr);
changed = classes_to_check->GetHighestBitSet() != -1;
temp_.cice.ending_classes_to_check_matrix[bb->id] = classes_to_check;
// Create a new classes_to_check for next BB.
temp_.cice.work_classes_to_check = new (temp_scoped_alloc_.get()) ArenaBitVector(
temp_scoped_alloc_.get(), temp_.cice.num_class_bits, false, kBitMapClInitCheck);
} else if (!classes_to_check->Equal(old_ending_classes_to_check)) {
changed = true;
temp_.cice.ending_classes_to_check_matrix[bb->id] = classes_to_check;
temp_.cice.work_classes_to_check = old_ending_classes_to_check; // Reuse for next BB.
}
return changed;
}
void MIRGraph::EliminateClassInitChecksEnd() {
// Clean up temporaries.
temp_.cice.num_class_bits = 0u;
temp_.cice.work_classes_to_check = nullptr;
temp_.cice.ending_classes_to_check_matrix = nullptr;
DCHECK(temp_.cice.indexes != nullptr);
temp_.cice.indexes = nullptr;
DCHECK(temp_scoped_alloc_.get() != nullptr);
temp_scoped_alloc_.reset();
}
static void DisableGVNDependentOptimizations(CompilationUnit* cu) {
cu->disable_opt |= (1u << kGvnDeadCodeElimination);
}
bool MIRGraph::ApplyGlobalValueNumberingGate() {
if (GlobalValueNumbering::Skip(cu_)) {
DisableGVNDependentOptimizations(cu_);
return false;
}
DCHECK(temp_scoped_alloc_ == nullptr);
temp_scoped_alloc_.reset(ScopedArenaAllocator::Create(&cu_->arena_stack));
temp_.gvn.ifield_ids =
GlobalValueNumbering::PrepareGvnFieldIds(temp_scoped_alloc_.get(), ifield_lowering_infos_);
temp_.gvn.sfield_ids =
GlobalValueNumbering::PrepareGvnFieldIds(temp_scoped_alloc_.get(), sfield_lowering_infos_);
DCHECK(temp_.gvn.gvn == nullptr);
temp_.gvn.gvn = new (temp_scoped_alloc_.get()) GlobalValueNumbering(
cu_, temp_scoped_alloc_.get(), GlobalValueNumbering::kModeGvn);
return true;
}
bool MIRGraph::ApplyGlobalValueNumbering(BasicBlock* bb) {
DCHECK(temp_.gvn.gvn != nullptr);
LocalValueNumbering* lvn = temp_.gvn.gvn->PrepareBasicBlock(bb);
if (lvn != nullptr) {
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
lvn->GetValueNumber(mir);
}
}
bool change = (lvn != nullptr) && temp_.gvn.gvn->FinishBasicBlock(bb);
return change;
}
void MIRGraph::ApplyGlobalValueNumberingEnd() {
// Perform modifications.
DCHECK(temp_.gvn.gvn != nullptr);
if (temp_.gvn.gvn->Good()) {
temp_.gvn.gvn->StartPostProcessing();
if (max_nested_loops_ != 0u) {
TopologicalSortIterator iter(this);
for (BasicBlock* bb = iter.Next(); bb != nullptr; bb = iter.Next()) {
ScopedArenaAllocator allocator(&cu_->arena_stack); // Reclaim memory after each LVN.
LocalValueNumbering* lvn = temp_.gvn.gvn->PrepareBasicBlock(bb, &allocator);
if (lvn != nullptr) {
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
lvn->GetValueNumber(mir);
}
bool change = temp_.gvn.gvn->FinishBasicBlock(bb);
DCHECK(!change) << PrettyMethod(cu_->method_idx, *cu_->dex_file);
}
}
}
// GVN was successful, running the LVN would be useless.
cu_->disable_opt |= (1u << kLocalValueNumbering);
} else {
LOG(WARNING) << "GVN failed for " << PrettyMethod(cu_->method_idx, *cu_->dex_file);
DisableGVNDependentOptimizations(cu_);
}
}
bool MIRGraph::EliminateDeadCodeGate() {
if ((cu_->disable_opt & (1 << kGvnDeadCodeElimination)) != 0 || temp_.gvn.gvn == nullptr) {
return false;
}
DCHECK(temp_scoped_alloc_ != nullptr);
temp_.gvn.dce = new (temp_scoped_alloc_.get()) GvnDeadCodeElimination(temp_.gvn.gvn,
temp_scoped_alloc_.get());
return true;
}
bool MIRGraph::EliminateDeadCode(BasicBlock* bb) {
DCHECK(temp_scoped_alloc_ != nullptr);
DCHECK(temp_.gvn.gvn != nullptr);
if (bb->block_type != kDalvikByteCode) {
return false;
}
DCHECK(temp_.gvn.dce != nullptr);
temp_.gvn.dce->Apply(bb);
return false; // No need to repeat.
}
void MIRGraph::EliminateDeadCodeEnd() {
if (kIsDebugBuild) {
// DCE can make some previously dead vregs alive again. Make sure the obsolete
// live-in information is not used anymore.
AllNodesIterator iter(this);
for (BasicBlock* bb = iter.Next(); bb != nullptr; bb = iter.Next()) {
if (bb->data_flow_info != nullptr) {
bb->data_flow_info->live_in_v = nullptr;
}
}
}
}
void MIRGraph::GlobalValueNumberingCleanup() {
// If the GVN didn't run, these pointers should be null and everything is effectively no-op.
delete temp_.gvn.dce;
temp_.gvn.dce = nullptr;
delete temp_.gvn.gvn;
temp_.gvn.gvn = nullptr;
temp_.gvn.ifield_ids = nullptr;
temp_.gvn.sfield_ids = nullptr;
temp_scoped_alloc_.reset();
}
void MIRGraph::ComputeInlineIFieldLoweringInfo(uint16_t field_idx, MIR* invoke, MIR* iget_or_iput) {
uint32_t method_index = invoke->meta.method_lowering_info;
if (temp_.smi.processed_indexes->IsBitSet(method_index)) {
iget_or_iput->meta.ifield_lowering_info = temp_.smi.lowering_infos[method_index];
DCHECK_EQ(field_idx, GetIFieldLoweringInfo(iget_or_iput).FieldIndex());
return;
}
const MirMethodLoweringInfo& method_info = GetMethodLoweringInfo(invoke);
MethodReference target = method_info.GetTargetMethod();
ScopedObjectAccess soa(Thread::Current());
StackHandleScope<1> hs(soa.Self());
Handle<mirror::DexCache> dex_cache(
hs.NewHandle(cu_->class_linker->FindDexCache(hs.Self(), *target.dex_file)));
DexCompilationUnit inlined_unit(cu_,
cu_->class_loader,
cu_->class_linker,
*target.dex_file,
nullptr /* code_item not used */,
0u /* class_def_idx not used */,
target.dex_method_index,
0u /* access_flags not used */,
nullptr /* verified_method not used */,
dex_cache);
DexMemAccessType type = IGetOrIPutMemAccessType(iget_or_iput->dalvikInsn.opcode);
MirIFieldLoweringInfo inlined_field_info(field_idx, type, false);
MirIFieldLoweringInfo::Resolve(soa, cu_->compiler_driver, &inlined_unit, &inlined_field_info, 1u);
DCHECK(inlined_field_info.IsResolved());
uint32_t field_info_index = ifield_lowering_infos_.size();
ifield_lowering_infos_.push_back(inlined_field_info);
temp_.smi.processed_indexes->SetBit(method_index);
temp_.smi.lowering_infos[method_index] = field_info_index;
iget_or_iput->meta.ifield_lowering_info = field_info_index;
}
bool MIRGraph::InlineSpecialMethodsGate() {
if ((cu_->disable_opt & (1 << kSuppressMethodInlining)) != 0 ||
method_lowering_infos_.size() == 0u) {
return false;
}
if (cu_->compiler_driver->GetMethodInlinerMap() == nullptr) {
// This isn't the Quick compiler.
return false;
}
return true;
}
void MIRGraph::InlineSpecialMethodsStart() {
// Prepare for inlining getters/setters. Since we're inlining at most 1 IGET/IPUT from
// each INVOKE, we can index the data by the MIR::meta::method_lowering_info index.
DCHECK(temp_scoped_alloc_.get() == nullptr);
temp_scoped_alloc_.reset(ScopedArenaAllocator::Create(&cu_->arena_stack));
temp_.smi.num_indexes = method_lowering_infos_.size();
temp_.smi.processed_indexes = new (temp_scoped_alloc_.get()) ArenaBitVector(
temp_scoped_alloc_.get(), temp_.smi.num_indexes, false, kBitMapMisc);
temp_.smi.processed_indexes->ClearAllBits();
temp_.smi.lowering_infos =
temp_scoped_alloc_->AllocArray<uint16_t>(temp_.smi.num_indexes, kArenaAllocGrowableArray);
}
void MIRGraph::InlineSpecialMethods(BasicBlock* bb) {
if (bb->block_type != kDalvikByteCode) {
return;
}
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
if (MIR::DecodedInstruction::IsPseudoMirOp(mir->dalvikInsn.opcode)) {
continue;
}
if (!(mir->dalvikInsn.FlagsOf() & Instruction::kInvoke)) {
continue;
}
const MirMethodLoweringInfo& method_info = GetMethodLoweringInfo(mir);
if (!method_info.FastPath() || !method_info.IsSpecial()) {
continue;
}
InvokeType sharp_type = method_info.GetSharpType();
if ((sharp_type != kDirect) && (sharp_type != kStatic)) {
continue;
}
if (sharp_type == kStatic) {
bool needs_clinit = !method_info.IsClassInitialized() &&
((mir->optimization_flags & MIR_CLASS_IS_INITIALIZED) == 0);
if (needs_clinit) {
continue;
}
}
DCHECK(cu_->compiler_driver->GetMethodInlinerMap() != nullptr);
MethodReference target = method_info.GetTargetMethod();
if (cu_->compiler_driver->GetMethodInlinerMap()->GetMethodInliner(target.dex_file)
->GenInline(this, bb, mir, target.dex_method_index)) {
if (cu_->verbose || cu_->print_pass) {
LOG(INFO) << "SpecialMethodInliner: Inlined " << method_info.GetInvokeType() << " ("
<< sharp_type << ") call to \"" << PrettyMethod(target.dex_method_index,
*target.dex_file)
<< "\" from \"" << PrettyMethod(cu_->method_idx, *cu_->dex_file)
<< "\" @0x" << std::hex << mir->offset;
}
}
}
}
void MIRGraph::InlineSpecialMethodsEnd() {
// Clean up temporaries.
DCHECK(temp_.smi.lowering_infos != nullptr);
temp_.smi.lowering_infos = nullptr;
temp_.smi.num_indexes = 0u;
DCHECK(temp_.smi.processed_indexes != nullptr);
temp_.smi.processed_indexes = nullptr;
DCHECK(temp_scoped_alloc_.get() != nullptr);
temp_scoped_alloc_.reset();
}
void MIRGraph::DumpCheckStats() {
Checkstats* stats =
static_cast<Checkstats*>(arena_->Alloc(sizeof(Checkstats), kArenaAllocDFInfo));
checkstats_ = stats;
AllNodesIterator iter(this);
for (BasicBlock* bb = iter.Next(); bb != nullptr; bb = iter.Next()) {
CountChecks(bb);
}
if (stats->null_checks > 0) {
float eliminated = static_cast<float>(stats->null_checks_eliminated);
float checks = static_cast<float>(stats->null_checks);
LOG(INFO) << "Null Checks: " << PrettyMethod(cu_->method_idx, *cu_->dex_file) << " "
<< stats->null_checks_eliminated << " of " << stats->null_checks << " -> "
<< (eliminated/checks) * 100.0 << "%";
}
if (stats->range_checks > 0) {
float eliminated = static_cast<float>(stats->range_checks_eliminated);
float checks = static_cast<float>(stats->range_checks);
LOG(INFO) << "Range Checks: " << PrettyMethod(cu_->method_idx, *cu_->dex_file) << " "
<< stats->range_checks_eliminated << " of " << stats->range_checks << " -> "
<< (eliminated/checks) * 100.0 << "%";
}
}
bool MIRGraph::BuildExtendedBBList(class BasicBlock* bb) {
if (bb->visited) return false;
if (!((bb->block_type == kEntryBlock) || (bb->block_type == kDalvikByteCode)
|| (bb->block_type == kExitBlock))) {
// Ignore special blocks
bb->visited = true;
return false;
}
// Must be head of extended basic block.
BasicBlock* start_bb = bb;
extended_basic_blocks_.push_back(bb->id);
bool terminated_by_return = false;
bool do_local_value_numbering = false;
// Visit blocks strictly dominated by this head.
while (bb != nullptr) {
bb->visited = true;
terminated_by_return |= bb->terminated_by_return;
do_local_value_numbering |= bb->use_lvn;
bb = NextDominatedBlock(bb);
}
if (terminated_by_return || do_local_value_numbering) {
// Do lvn for all blocks in this extended set.
bb = start_bb;
while (bb != nullptr) {
bb->use_lvn = do_local_value_numbering;
bb->dominates_return = terminated_by_return;
bb = NextDominatedBlock(bb);
}
}
return false; // Not iterative - return value will be ignored
}
void MIRGraph::BasicBlockOptimizationStart() {
if ((cu_->disable_opt & (1 << kLocalValueNumbering)) == 0) {
temp_scoped_alloc_.reset(ScopedArenaAllocator::Create(&cu_->arena_stack));
temp_.gvn.ifield_ids =
GlobalValueNumbering::PrepareGvnFieldIds(temp_scoped_alloc_.get(), ifield_lowering_infos_);
temp_.gvn.sfield_ids =
GlobalValueNumbering::PrepareGvnFieldIds(temp_scoped_alloc_.get(), sfield_lowering_infos_);
}
}
void MIRGraph::BasicBlockOptimization() {
if ((cu_->disable_opt & (1 << kSuppressExceptionEdges)) != 0) {
ClearAllVisitedFlags();
PreOrderDfsIterator iter2(this);
for (BasicBlock* bb = iter2.Next(); bb != nullptr; bb = iter2.Next()) {
BuildExtendedBBList(bb);
}
// Perform extended basic block optimizations.
for (unsigned int i = 0; i < extended_basic_blocks_.size(); i++) {
BasicBlockOpt(GetBasicBlock(extended_basic_blocks_[i]));
}
} else {
PreOrderDfsIterator iter(this);
for (BasicBlock* bb = iter.Next(); bb != nullptr; bb = iter.Next()) {
BasicBlockOpt(bb);
}
}
}
void MIRGraph::BasicBlockOptimizationEnd() {
// Clean up after LVN.
temp_.gvn.ifield_ids = nullptr;
temp_.gvn.sfield_ids = nullptr;
temp_scoped_alloc_.reset();
}
void MIRGraph::StringChange() {
AllNodesIterator iter(this);
for (BasicBlock* bb = iter.Next(); bb != nullptr; bb = iter.Next()) {
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
// Look for new instance opcodes, skip otherwise
Instruction::Code opcode = mir->dalvikInsn.opcode;
if (opcode == Instruction::NEW_INSTANCE) {
uint32_t type_idx = mir->dalvikInsn.vB;
if (cu_->compiler_driver->IsStringTypeIndex(type_idx, cu_->dex_file)) {
LOG(FATAL) << "Quick cannot compile String allocations";
}
} else if ((opcode == Instruction::INVOKE_DIRECT) ||
(opcode == Instruction::INVOKE_DIRECT_RANGE)) {
uint32_t method_idx = mir->dalvikInsn.vB;
DexFileMethodInliner* inliner =
cu_->compiler_driver->GetMethodInlinerMap()->GetMethodInliner(cu_->dex_file);
if (inliner->IsStringInitMethodIndex(method_idx)) {
LOG(FATAL) << "Quick cannot compile String allocations";
}
}
}
}
}
bool MIRGraph::EliminateSuspendChecksGate() {
if (kLeafOptimization || // Incompatible (could create loops without suspend checks).
(cu_->disable_opt & (1 << kSuspendCheckElimination)) != 0 || // Disabled.
GetMaxNestedLoops() == 0u || // Nothing to do.
GetMaxNestedLoops() >= 32u || // Only 32 bits in suspend_checks_in_loops_[.].
// Exclude 32 as well to keep bit shifts well-defined.
!HasInvokes()) { // No invokes to actually eliminate any suspend checks.
return false;
}
suspend_checks_in_loops_ = arena_->AllocArray<uint32_t>(GetNumBlocks(), kArenaAllocMisc);
return true;
}
bool MIRGraph::EliminateSuspendChecks(BasicBlock* bb) {
if (bb->block_type != kDalvikByteCode) {
return false;
}
DCHECK_EQ(GetTopologicalSortOrderLoopHeadStack()->size(), bb->nesting_depth);
if (bb->nesting_depth == 0u) {
// Out of loops.
DCHECK_EQ(suspend_checks_in_loops_[bb->id], 0u); // The array was zero-initialized.
return false;
}
uint32_t suspend_checks_in_loops = (1u << bb->nesting_depth) - 1u; // Start with all loop heads.
bool found_invoke = false;
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
if ((IsInstructionInvoke(mir->dalvikInsn.opcode) ||
IsInstructionQuickInvoke(mir->dalvikInsn.opcode)) &&
!GetMethodLoweringInfo(mir).IsIntrinsic()) {
// Non-intrinsic invoke, rely on a suspend point in the invoked method.
found_invoke = true;
break;
}
}
if (!found_invoke) {
// Intersect suspend checks from predecessors.
uint16_t bb_topo_idx = topological_order_indexes_[bb->id];
uint32_t pred_mask_union = 0u;
for (BasicBlockId pred_id : bb->predecessors) {
uint16_t pred_topo_idx = topological_order_indexes_[pred_id];
if (pred_topo_idx < bb_topo_idx) {
// Determine the loop depth of the predecessors relative to this block.
size_t pred_loop_depth = topological_order_loop_head_stack_.size();
while (pred_loop_depth != 0u &&
pred_topo_idx < topological_order_loop_head_stack_[pred_loop_depth - 1].first) {
--pred_loop_depth;
}
DCHECK_LE(pred_loop_depth, GetBasicBlock(pred_id)->nesting_depth);
uint32_t pred_mask = (1u << pred_loop_depth) - 1u;
// Intersect pred_mask bits in suspend_checks_in_loops with
// suspend_checks_in_loops_[pred_id].
uint32_t pred_loops_without_checks = pred_mask & ~suspend_checks_in_loops_[pred_id];
suspend_checks_in_loops = suspend_checks_in_loops & ~pred_loops_without_checks;
pred_mask_union |= pred_mask;
}
}
// DCHECK_EQ() may not hold for unnatural loop heads, so use DCHECK_GE().
DCHECK_GE(((1u << (IsLoopHead(bb->id) ? bb->nesting_depth - 1u: bb->nesting_depth)) - 1u),
pred_mask_union);
suspend_checks_in_loops &= pred_mask_union;
}
suspend_checks_in_loops_[bb->id] = suspend_checks_in_loops;
if (suspend_checks_in_loops == 0u) {
return false;
}
// Apply MIR_IGNORE_SUSPEND_CHECK if appropriate.
if (bb->taken != NullBasicBlockId) {
DCHECK(bb->last_mir_insn != nullptr);
DCHECK(IsInstructionIfCc(bb->last_mir_insn->dalvikInsn.opcode) ||
IsInstructionIfCcZ(bb->last_mir_insn->dalvikInsn.opcode) ||
IsInstructionGoto(bb->last_mir_insn->dalvikInsn.opcode) ||
(static_cast<int>(bb->last_mir_insn->dalvikInsn.opcode) >= kMirOpFusedCmplFloat &&
static_cast<int>(bb->last_mir_insn->dalvikInsn.opcode) <= kMirOpFusedCmpLong));
if (!IsSuspendCheckEdge(bb, bb->taken) &&
(bb->fall_through == NullBasicBlockId || !IsSuspendCheckEdge(bb, bb->fall_through))) {
bb->last_mir_insn->optimization_flags |= MIR_IGNORE_SUSPEND_CHECK;
}
} else if (bb->fall_through != NullBasicBlockId && IsSuspendCheckEdge(bb, bb->fall_through)) {
// We've got a fall-through suspend edge. Add an artificial GOTO to force suspend check.
MIR* mir = NewMIR();
mir->dalvikInsn.opcode = Instruction::GOTO;
mir->dalvikInsn.vA = 0; // Branch offset.
mir->offset = GetBasicBlock(bb->fall_through)->start_offset;
mir->m_unit_index = current_method_;
mir->ssa_rep = reinterpret_cast<SSARepresentation*>(
arena_->Alloc(sizeof(SSARepresentation), kArenaAllocDFInfo)); // Zero-initialized.
bb->AppendMIR(mir);
std::swap(bb->fall_through, bb->taken); // The fall-through has become taken.
}
return true;
}
bool MIRGraph::CanThrow(MIR* mir) const {
if ((mir->dalvikInsn.FlagsOf() & Instruction::kThrow) == 0) {
return false;
}
const int opt_flags = mir->optimization_flags;
uint64_t df_attributes = GetDataFlowAttributes(mir);
// First, check if the insn can still throw NPE.
if (((df_attributes & DF_HAS_NULL_CHKS) != 0) && ((opt_flags & MIR_IGNORE_NULL_CHECK) == 0)) {
return true;
}
// Now process specific instructions.
if ((df_attributes & DF_IFIELD) != 0) {
// The IGET/IPUT family. We have processed the IGET/IPUT null check above.
DCHECK_NE(opt_flags & MIR_IGNORE_NULL_CHECK, 0);
// If not fast, weird things can happen and the insn can throw.
const MirIFieldLoweringInfo& field_info = GetIFieldLoweringInfo(mir);
bool fast = (df_attributes & DF_DA) != 0 ? field_info.FastGet() : field_info.FastPut();
return !fast;
} else if ((df_attributes & DF_SFIELD) != 0) {
// The SGET/SPUT family. Check for potentially throwing class initialization.
// Also, if not fast, weird things can happen and the insn can throw.
const MirSFieldLoweringInfo& field_info = GetSFieldLoweringInfo(mir);
bool fast = (df_attributes & DF_DA) != 0 ? field_info.FastGet() : field_info.FastPut();
bool is_class_initialized = field_info.IsClassInitialized() ||
((mir->optimization_flags & MIR_CLASS_IS_INITIALIZED) != 0);
return !(fast && is_class_initialized);
} else if ((df_attributes & DF_HAS_RANGE_CHKS) != 0) {
// Only AGET/APUT have range checks. We have processed the AGET/APUT null check above.
DCHECK_NE(opt_flags & MIR_IGNORE_NULL_CHECK, 0);
// Non-throwing only if range check has been eliminated.
return ((opt_flags & MIR_IGNORE_RANGE_CHECK) == 0);
} else if (mir->dalvikInsn.opcode == Instruction::CHECK_CAST &&
(opt_flags & MIR_IGNORE_CHECK_CAST) != 0) {
return false;
} else if (mir->dalvikInsn.opcode == Instruction::ARRAY_LENGTH ||
static_cast<int>(mir->dalvikInsn.opcode) == kMirOpNullCheck) {
// No more checks for these (null check was processed above).
return false;
}
return true;
}
bool MIRGraph::HasAntiDependency(MIR* first, MIR* second) {
DCHECK(first->ssa_rep != nullptr);
DCHECK(second->ssa_rep != nullptr);
if ((second->ssa_rep->num_defs > 0) && (first->ssa_rep->num_uses > 0)) {
int vreg0 = SRegToVReg(second->ssa_rep->defs[0]);
int vreg1 = (second->ssa_rep->num_defs == 2) ?
SRegToVReg(second->ssa_rep->defs[1]) : INVALID_VREG;
for (int i = 0; i < first->ssa_rep->num_uses; i++) {
int32_t use = SRegToVReg(first->ssa_rep->uses[i]);
if (use == vreg0 || use == vreg1) {
return true;
}
}
}
return false;
}
void MIRGraph::CombineMultiplyAdd(MIR* mul_mir, MIR* add_mir, bool mul_is_first_addend,
bool is_wide, bool is_sub) {
if (is_wide) {
if (is_sub) {
add_mir->dalvikInsn.opcode = static_cast<Instruction::Code>(kMirOpMsubLong);
} else {
add_mir->dalvikInsn.opcode = static_cast<Instruction::Code>(kMirOpMaddLong);
}
} else {
if (is_sub) {
add_mir->dalvikInsn.opcode = static_cast<Instruction::Code>(kMirOpMsubInt);
} else {
add_mir->dalvikInsn.opcode = static_cast<Instruction::Code>(kMirOpMaddInt);
}
}
add_mir->ssa_rep->num_uses = is_wide ? 6 : 3;
int32_t addend0 = INVALID_SREG;
int32_t addend1 = INVALID_SREG;
if (is_wide) {
addend0 = mul_is_first_addend ? add_mir->ssa_rep->uses[2] : add_mir->ssa_rep->uses[0];
addend1 = mul_is_first_addend ? add_mir->ssa_rep->uses[3] : add_mir->ssa_rep->uses[1];
} else {
addend0 = mul_is_first_addend ? add_mir->ssa_rep->uses[1] : add_mir->ssa_rep->uses[0];
}
AllocateSSAUseData(add_mir, add_mir->ssa_rep->num_uses);
add_mir->ssa_rep->uses[0] = mul_mir->ssa_rep->uses[0];
add_mir->ssa_rep->uses[1] = mul_mir->ssa_rep->uses[1];
// Clear the original multiply product ssa use count, as it is not used anymore.
raw_use_counts_[mul_mir->ssa_rep->defs[0]] = 0;
use_counts_[mul_mir->ssa_rep->defs[0]] = 0;
if (is_wide) {
DCHECK_EQ(add_mir->ssa_rep->num_uses, 6);
add_mir->ssa_rep->uses[2] = mul_mir->ssa_rep->uses[2];
add_mir->ssa_rep->uses[3] = mul_mir->ssa_rep->uses[3];
add_mir->ssa_rep->uses[4] = addend0;
add_mir->ssa_rep->uses[5] = addend1;
raw_use_counts_[mul_mir->ssa_rep->defs[1]] = 0;
use_counts_[mul_mir->ssa_rep->defs[1]] = 0;
} else {
DCHECK_EQ(add_mir->ssa_rep->num_uses, 3);
add_mir->ssa_rep->uses[2] = addend0;
}
// Copy in the decoded instruction information.
add_mir->dalvikInsn.vB = SRegToVReg(add_mir->ssa_rep->uses[0]);
if (is_wide) {
add_mir->dalvikInsn.vC = SRegToVReg(add_mir->ssa_rep->uses[2]);
add_mir->dalvikInsn.arg[0] = SRegToVReg(add_mir->ssa_rep->uses[4]);
} else {
add_mir->dalvikInsn.vC = SRegToVReg(add_mir->ssa_rep->uses[1]);
add_mir->dalvikInsn.arg[0] = SRegToVReg(add_mir->ssa_rep->uses[2]);
}
// Original multiply MIR is set to Nop.
mul_mir->dalvikInsn.opcode = static_cast<Instruction::Code>(kMirOpNop);
}
void MIRGraph::MultiplyAddOpt(BasicBlock* bb) {
if (bb->block_type == kDead) {
return;
}
ScopedArenaAllocator allocator(&cu_->arena_stack);
ScopedArenaSafeMap<uint32_t, MIR*> ssa_mul_map(std::less<uint32_t>(), allocator.Adapter());
ScopedArenaSafeMap<uint32_t, MIR*>::iterator map_it;
for (MIR* mir = bb->first_mir_insn; mir != nullptr; mir = mir->next) {
Instruction::Code opcode = mir->dalvikInsn.opcode;
bool is_sub = true;
bool is_candidate_multiply = false;
switch (opcode) {
case Instruction::MUL_INT:
case Instruction::MUL_INT_2ADDR:
is_candidate_multiply = true;
break;
case Instruction::MUL_LONG:
case Instruction::MUL_LONG_2ADDR:
if (cu_->target64) {
is_candidate_multiply = true;
}
break;
case Instruction::ADD_INT:
case Instruction::ADD_INT_2ADDR:
is_sub = false;
FALLTHROUGH_INTENDED;
case Instruction::SUB_INT:
case Instruction::SUB_INT_2ADDR:
if (((map_it = ssa_mul_map.find(mir->ssa_rep->uses[0])) != ssa_mul_map.end()) && !is_sub) {
// a*b+c
CombineMultiplyAdd(map_it->second, mir, true /* product is the first addend */,
false /* is_wide */, false /* is_sub */);
ssa_mul_map.erase(mir->ssa_rep->uses[0]);
} else if ((map_it = ssa_mul_map.find(mir->ssa_rep->uses[1])) != ssa_mul_map.end()) {
// c+a*b or c-a*b
CombineMultiplyAdd(map_it->second, mir, false /* product is the second addend */,
false /* is_wide */, is_sub);
ssa_mul_map.erase(map_it);
}
break;
case Instruction::ADD_LONG:
case Instruction::ADD_LONG_2ADDR:
is_sub = false;
FALLTHROUGH_INTENDED;
case Instruction::SUB_LONG:
case Instruction::SUB_LONG_2ADDR:
if (!cu_->target64) {
break;
}
if ((map_it = ssa_mul_map.find(mir->ssa_rep->uses[0])) != ssa_mul_map.end() && !is_sub) {
// a*b+c
CombineMultiplyAdd(map_it->second, mir, true /* product is the first addend */,
true /* is_wide */, false /* is_sub */);
ssa_mul_map.erase(map_it);
} else if ((map_it = ssa_mul_map.find(mir->ssa_rep->uses[2])) != ssa_mul_map.end()) {
// c+a*b or c-a*b
CombineMultiplyAdd(map_it->second, mir, false /* product is the second addend */,
true /* is_wide */, is_sub);
ssa_mul_map.erase(map_it);
}
break;
default:
if (!ssa_mul_map.empty() && CanThrow(mir)) {
// Should not combine multiply and add MIRs across potential exception.
ssa_mul_map.clear();
}
break;
}
// Exclude the case when an MIR writes a vreg which is previous candidate multiply MIR's uses.
// It is because that current RA may allocate the same physical register to them. For this
// kind of cases, the multiplier has been updated, we should not use updated value to the
// multiply-add insn.
if (ssa_mul_map.size() > 0) {
for (auto it = ssa_mul_map.begin(); it != ssa_mul_map.end();) {
MIR* mul = it->second;
if (HasAntiDependency(mul, mir)) {
it = ssa_mul_map.erase(it);
} else {
++it;
}
}
}
if (is_candidate_multiply &&
(GetRawUseCount(mir->ssa_rep->defs[0]) == 1) && (mir->next != nullptr)) {
ssa_mul_map.Put(mir->ssa_rep->defs[0], mir);
}
}
}
} // namespace art