| /* |
| * Copyright (C) 2016 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 "loop_optimization.h" |
| |
| #include "arch/arm/instruction_set_features_arm.h" |
| #include "arch/arm64/instruction_set_features_arm64.h" |
| #include "arch/instruction_set.h" |
| #include "arch/mips/instruction_set_features_mips.h" |
| #include "arch/mips64/instruction_set_features_mips64.h" |
| #include "arch/x86/instruction_set_features_x86.h" |
| #include "arch/x86_64/instruction_set_features_x86_64.h" |
| #include "driver/compiler_driver.h" |
| #include "linear_order.h" |
| #include "mirror/array-inl.h" |
| #include "mirror/string.h" |
| |
| namespace art { |
| |
| // Enables vectorization (SIMDization) in the loop optimizer. |
| static constexpr bool kEnableVectorization = true; |
| |
| // Enables scalar loop unrolling in the loop optimizer. |
| static constexpr bool kEnableScalarPeelingUnrolling = false; |
| |
| // |
| // Static helpers. |
| // |
| |
| // Base alignment for arrays/strings guaranteed by the Android runtime. |
| static uint32_t BaseAlignment() { |
| return kObjectAlignment; |
| } |
| |
| // Hidden offset for arrays/strings guaranteed by the Android runtime. |
| static uint32_t HiddenOffset(DataType::Type type, bool is_string_char_at) { |
| return is_string_char_at |
| ? mirror::String::ValueOffset().Uint32Value() |
| : mirror::Array::DataOffset(DataType::Size(type)).Uint32Value(); |
| } |
| |
| // Remove the instruction from the graph. A bit more elaborate than the usual |
| // instruction removal, since there may be a cycle in the use structure. |
| static void RemoveFromCycle(HInstruction* instruction) { |
| instruction->RemoveAsUserOfAllInputs(); |
| instruction->RemoveEnvironmentUsers(); |
| instruction->GetBlock()->RemoveInstructionOrPhi(instruction, /*ensure_safety=*/ false); |
| RemoveEnvironmentUses(instruction); |
| ResetEnvironmentInputRecords(instruction); |
| } |
| |
| // Detect a goto block and sets succ to the single successor. |
| static bool IsGotoBlock(HBasicBlock* block, /*out*/ HBasicBlock** succ) { |
| if (block->GetPredecessors().size() == 1 && |
| block->GetSuccessors().size() == 1 && |
| block->IsSingleGoto()) { |
| *succ = block->GetSingleSuccessor(); |
| return true; |
| } |
| return false; |
| } |
| |
| // Detect an early exit loop. |
| static bool IsEarlyExit(HLoopInformation* loop_info) { |
| HBlocksInLoopReversePostOrderIterator it_loop(*loop_info); |
| for (it_loop.Advance(); !it_loop.Done(); it_loop.Advance()) { |
| for (HBasicBlock* successor : it_loop.Current()->GetSuccessors()) { |
| if (!loop_info->Contains(*successor)) { |
| return true; |
| } |
| } |
| } |
| return false; |
| } |
| |
| // Forward declaration. |
| static bool IsZeroExtensionAndGet(HInstruction* instruction, |
| DataType::Type type, |
| /*out*/ HInstruction** operand); |
| |
| // Detect a sign extension in instruction from the given type. |
| // Returns the promoted operand on success. |
| static bool IsSignExtensionAndGet(HInstruction* instruction, |
| DataType::Type type, |
| /*out*/ HInstruction** operand) { |
| // Accept any already wider constant that would be handled properly by sign |
| // extension when represented in the *width* of the given narrower data type |
| // (the fact that Uint8/Uint16 normally zero extend does not matter here). |
| int64_t value = 0; |
| if (IsInt64AndGet(instruction, /*out*/ &value)) { |
| switch (type) { |
| case DataType::Type::kUint8: |
| case DataType::Type::kInt8: |
| if (IsInt<8>(value)) { |
| *operand = instruction; |
| return true; |
| } |
| return false; |
| case DataType::Type::kUint16: |
| case DataType::Type::kInt16: |
| if (IsInt<16>(value)) { |
| *operand = instruction; |
| return true; |
| } |
| return false; |
| default: |
| return false; |
| } |
| } |
| // An implicit widening conversion of any signed expression sign-extends. |
| if (instruction->GetType() == type) { |
| switch (type) { |
| case DataType::Type::kInt8: |
| case DataType::Type::kInt16: |
| *operand = instruction; |
| return true; |
| default: |
| return false; |
| } |
| } |
| // An explicit widening conversion of a signed expression sign-extends. |
| if (instruction->IsTypeConversion()) { |
| HInstruction* conv = instruction->InputAt(0); |
| DataType::Type from = conv->GetType(); |
| switch (instruction->GetType()) { |
| case DataType::Type::kInt32: |
| case DataType::Type::kInt64: |
| if (type == from && (from == DataType::Type::kInt8 || |
| from == DataType::Type::kInt16 || |
| from == DataType::Type::kInt32)) { |
| *operand = conv; |
| return true; |
| } |
| return false; |
| case DataType::Type::kInt16: |
| return type == DataType::Type::kUint16 && |
| from == DataType::Type::kUint16 && |
| IsZeroExtensionAndGet(instruction->InputAt(0), type, /*out*/ operand); |
| default: |
| return false; |
| } |
| } |
| return false; |
| } |
| |
| // Detect a zero extension in instruction from the given type. |
| // Returns the promoted operand on success. |
| static bool IsZeroExtensionAndGet(HInstruction* instruction, |
| DataType::Type type, |
| /*out*/ HInstruction** operand) { |
| // Accept any already wider constant that would be handled properly by zero |
| // extension when represented in the *width* of the given narrower data type |
| // (the fact that Int8/Int16 normally sign extend does not matter here). |
| int64_t value = 0; |
| if (IsInt64AndGet(instruction, /*out*/ &value)) { |
| switch (type) { |
| case DataType::Type::kUint8: |
| case DataType::Type::kInt8: |
| if (IsUint<8>(value)) { |
| *operand = instruction; |
| return true; |
| } |
| return false; |
| case DataType::Type::kUint16: |
| case DataType::Type::kInt16: |
| if (IsUint<16>(value)) { |
| *operand = instruction; |
| return true; |
| } |
| return false; |
| default: |
| return false; |
| } |
| } |
| // An implicit widening conversion of any unsigned expression zero-extends. |
| if (instruction->GetType() == type) { |
| switch (type) { |
| case DataType::Type::kUint8: |
| case DataType::Type::kUint16: |
| *operand = instruction; |
| return true; |
| default: |
| return false; |
| } |
| } |
| // An explicit widening conversion of an unsigned expression zero-extends. |
| if (instruction->IsTypeConversion()) { |
| HInstruction* conv = instruction->InputAt(0); |
| DataType::Type from = conv->GetType(); |
| switch (instruction->GetType()) { |
| case DataType::Type::kInt32: |
| case DataType::Type::kInt64: |
| if (type == from && from == DataType::Type::kUint16) { |
| *operand = conv; |
| return true; |
| } |
| return false; |
| case DataType::Type::kUint16: |
| return type == DataType::Type::kInt16 && |
| from == DataType::Type::kInt16 && |
| IsSignExtensionAndGet(instruction->InputAt(0), type, /*out*/ operand); |
| default: |
| return false; |
| } |
| } |
| return false; |
| } |
| |
| // Detect situations with same-extension narrower operands. |
| // Returns true on success and sets is_unsigned accordingly. |
| static bool IsNarrowerOperands(HInstruction* a, |
| HInstruction* b, |
| DataType::Type type, |
| /*out*/ HInstruction** r, |
| /*out*/ HInstruction** s, |
| /*out*/ bool* is_unsigned) { |
| DCHECK(a != nullptr && b != nullptr); |
| // Look for a matching sign extension. |
| DataType::Type stype = HVecOperation::ToSignedType(type); |
| if (IsSignExtensionAndGet(a, stype, r) && IsSignExtensionAndGet(b, stype, s)) { |
| *is_unsigned = false; |
| return true; |
| } |
| // Look for a matching zero extension. |
| DataType::Type utype = HVecOperation::ToUnsignedType(type); |
| if (IsZeroExtensionAndGet(a, utype, r) && IsZeroExtensionAndGet(b, utype, s)) { |
| *is_unsigned = true; |
| return true; |
| } |
| return false; |
| } |
| |
| // As above, single operand. |
| static bool IsNarrowerOperand(HInstruction* a, |
| DataType::Type type, |
| /*out*/ HInstruction** r, |
| /*out*/ bool* is_unsigned) { |
| DCHECK(a != nullptr); |
| // Look for a matching sign extension. |
| DataType::Type stype = HVecOperation::ToSignedType(type); |
| if (IsSignExtensionAndGet(a, stype, r)) { |
| *is_unsigned = false; |
| return true; |
| } |
| // Look for a matching zero extension. |
| DataType::Type utype = HVecOperation::ToUnsignedType(type); |
| if (IsZeroExtensionAndGet(a, utype, r)) { |
| *is_unsigned = true; |
| return true; |
| } |
| return false; |
| } |
| |
| // Compute relative vector length based on type difference. |
| static uint32_t GetOtherVL(DataType::Type other_type, DataType::Type vector_type, uint32_t vl) { |
| DCHECK(DataType::IsIntegralType(other_type)); |
| DCHECK(DataType::IsIntegralType(vector_type)); |
| DCHECK_GE(DataType::SizeShift(other_type), DataType::SizeShift(vector_type)); |
| return vl >> (DataType::SizeShift(other_type) - DataType::SizeShift(vector_type)); |
| } |
| |
| // Detect up to two added operands a and b and an acccumulated constant c. |
| static bool IsAddConst(HInstruction* instruction, |
| /*out*/ HInstruction** a, |
| /*out*/ HInstruction** b, |
| /*out*/ int64_t* c, |
| int32_t depth = 8) { // don't search too deep |
| int64_t value = 0; |
| // Enter add/sub while still within reasonable depth. |
| if (depth > 0) { |
| if (instruction->IsAdd()) { |
| return IsAddConst(instruction->InputAt(0), a, b, c, depth - 1) && |
| IsAddConst(instruction->InputAt(1), a, b, c, depth - 1); |
| } else if (instruction->IsSub() && |
| IsInt64AndGet(instruction->InputAt(1), &value)) { |
| *c -= value; |
| return IsAddConst(instruction->InputAt(0), a, b, c, depth - 1); |
| } |
| } |
| // Otherwise, deal with leaf nodes. |
| if (IsInt64AndGet(instruction, &value)) { |
| *c += value; |
| return true; |
| } else if (*a == nullptr) { |
| *a = instruction; |
| return true; |
| } else if (*b == nullptr) { |
| *b = instruction; |
| return true; |
| } |
| return false; // too many operands |
| } |
| |
| // Detect a + b + c with optional constant c. |
| static bool IsAddConst2(HGraph* graph, |
| HInstruction* instruction, |
| /*out*/ HInstruction** a, |
| /*out*/ HInstruction** b, |
| /*out*/ int64_t* c) { |
| if (IsAddConst(instruction, a, b, c) && *a != nullptr) { |
| if (*b == nullptr) { |
| // Constant is usually already present, unless accumulated. |
| *b = graph->GetConstant(instruction->GetType(), (*c)); |
| *c = 0; |
| } |
| return true; |
| } |
| return false; |
| } |
| |
| // Detect a direct a - b or a hidden a - (-c). |
| static bool IsSubConst2(HGraph* graph, |
| HInstruction* instruction, |
| /*out*/ HInstruction** a, |
| /*out*/ HInstruction** b) { |
| int64_t c = 0; |
| if (instruction->IsSub()) { |
| *a = instruction->InputAt(0); |
| *b = instruction->InputAt(1); |
| return true; |
| } else if (IsAddConst(instruction, a, b, &c) && *a != nullptr && *b == nullptr) { |
| // Constant for the hidden subtraction. |
| *b = graph->GetConstant(instruction->GetType(), -c); |
| return true; |
| } |
| return false; |
| } |
| |
| // Detect reductions of the following forms, |
| // x = x_phi + .. |
| // x = x_phi - .. |
| static bool HasReductionFormat(HInstruction* reduction, HInstruction* phi) { |
| if (reduction->IsAdd()) { |
| return (reduction->InputAt(0) == phi && reduction->InputAt(1) != phi) || |
| (reduction->InputAt(0) != phi && reduction->InputAt(1) == phi); |
| } else if (reduction->IsSub()) { |
| return (reduction->InputAt(0) == phi && reduction->InputAt(1) != phi); |
| } |
| return false; |
| } |
| |
| // Translates vector operation to reduction kind. |
| static HVecReduce::ReductionKind GetReductionKind(HVecOperation* reduction) { |
| if (reduction->IsVecAdd() || reduction->IsVecSub() || reduction->IsVecSADAccumulate()) { |
| return HVecReduce::kSum; |
| } |
| LOG(FATAL) << "Unsupported SIMD reduction " << reduction->GetId(); |
| UNREACHABLE(); |
| } |
| |
| // Test vector restrictions. |
| static bool HasVectorRestrictions(uint64_t restrictions, uint64_t tested) { |
| return (restrictions & tested) != 0; |
| } |
| |
| // Insert an instruction. |
| static HInstruction* Insert(HBasicBlock* block, HInstruction* instruction) { |
| DCHECK(block != nullptr); |
| DCHECK(instruction != nullptr); |
| block->InsertInstructionBefore(instruction, block->GetLastInstruction()); |
| return instruction; |
| } |
| |
| // Check that instructions from the induction sets are fully removed: have no uses |
| // and no other instructions use them. |
| static bool CheckInductionSetFullyRemoved(ScopedArenaSet<HInstruction*>* iset) { |
| for (HInstruction* instr : *iset) { |
| if (instr->GetBlock() != nullptr || |
| !instr->GetUses().empty() || |
| !instr->GetEnvUses().empty() || |
| HasEnvironmentUsedByOthers(instr)) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| // Tries to statically evaluate condition of the specified "HIf" for other condition checks. |
| static void TryToEvaluateIfCondition(HIf* instruction, HGraph* graph) { |
| HInstruction* cond = instruction->InputAt(0); |
| |
| // If a condition 'cond' is evaluated in an HIf instruction then in the successors of the |
| // IF_BLOCK we statically know the value of the condition 'cond' (TRUE in TRUE_SUCC, FALSE in |
| // FALSE_SUCC). Using that we can replace another evaluation (use) EVAL of the same 'cond' |
| // with TRUE value (FALSE value) if every path from the ENTRY_BLOCK to EVAL_BLOCK contains the |
| // edge HIF_BLOCK->TRUE_SUCC (HIF_BLOCK->FALSE_SUCC). |
| // if (cond) { if(cond) { |
| // if (cond) {} if (1) {} |
| // } else { =======> } else { |
| // if (cond) {} if (0) {} |
| // } } |
| if (!cond->IsConstant()) { |
| HBasicBlock* true_succ = instruction->IfTrueSuccessor(); |
| HBasicBlock* false_succ = instruction->IfFalseSuccessor(); |
| |
| DCHECK_EQ(true_succ->GetPredecessors().size(), 1u); |
| DCHECK_EQ(false_succ->GetPredecessors().size(), 1u); |
| |
| const HUseList<HInstruction*>& uses = cond->GetUses(); |
| for (auto it = uses.begin(), end = uses.end(); it != end; /* ++it below */) { |
| HInstruction* user = it->GetUser(); |
| size_t index = it->GetIndex(); |
| HBasicBlock* user_block = user->GetBlock(); |
| // Increment `it` now because `*it` may disappear thanks to user->ReplaceInput(). |
| ++it; |
| if (true_succ->Dominates(user_block)) { |
| user->ReplaceInput(graph->GetIntConstant(1), index); |
| } else if (false_succ->Dominates(user_block)) { |
| user->ReplaceInput(graph->GetIntConstant(0), index); |
| } |
| } |
| } |
| } |
| |
| // |
| // Public methods. |
| // |
| |
| HLoopOptimization::HLoopOptimization(HGraph* graph, |
| CompilerDriver* compiler_driver, |
| HInductionVarAnalysis* induction_analysis, |
| OptimizingCompilerStats* stats, |
| const char* name) |
| : HOptimization(graph, name, stats), |
| compiler_driver_(compiler_driver), |
| induction_range_(induction_analysis), |
| loop_allocator_(nullptr), |
| global_allocator_(graph_->GetAllocator()), |
| top_loop_(nullptr), |
| last_loop_(nullptr), |
| iset_(nullptr), |
| reductions_(nullptr), |
| simplified_(false), |
| vector_length_(0), |
| vector_refs_(nullptr), |
| vector_static_peeling_factor_(0), |
| vector_dynamic_peeling_candidate_(nullptr), |
| vector_runtime_test_a_(nullptr), |
| vector_runtime_test_b_(nullptr), |
| vector_map_(nullptr), |
| vector_permanent_map_(nullptr), |
| vector_mode_(kSequential), |
| vector_preheader_(nullptr), |
| vector_header_(nullptr), |
| vector_body_(nullptr), |
| vector_index_(nullptr), |
| arch_loop_helper_(ArchDefaultLoopHelper::Create(compiler_driver_ != nullptr |
| ? compiler_driver_->GetInstructionSet() |
| : InstructionSet::kNone, |
| global_allocator_)) { |
| } |
| |
| bool HLoopOptimization::Run() { |
| // Skip if there is no loop or the graph has try-catch/irreducible loops. |
| // TODO: make this less of a sledgehammer. |
| if (!graph_->HasLoops() || graph_->HasTryCatch() || graph_->HasIrreducibleLoops()) { |
| return false; |
| } |
| |
| // Phase-local allocator. |
| ScopedArenaAllocator allocator(graph_->GetArenaStack()); |
| loop_allocator_ = &allocator; |
| |
| // Perform loop optimizations. |
| bool didLoopOpt = LocalRun(); |
| if (top_loop_ == nullptr) { |
| graph_->SetHasLoops(false); // no more loops |
| } |
| |
| // Detach. |
| loop_allocator_ = nullptr; |
| last_loop_ = top_loop_ = nullptr; |
| |
| return didLoopOpt; |
| } |
| |
| // |
| // Loop setup and traversal. |
| // |
| |
| bool HLoopOptimization::LocalRun() { |
| bool didLoopOpt = false; |
| // Build the linear order using the phase-local allocator. This step enables building |
| // a loop hierarchy that properly reflects the outer-inner and previous-next relation. |
| ScopedArenaVector<HBasicBlock*> linear_order(loop_allocator_->Adapter(kArenaAllocLinearOrder)); |
| LinearizeGraph(graph_, &linear_order); |
| |
| // Build the loop hierarchy. |
| for (HBasicBlock* block : linear_order) { |
| if (block->IsLoopHeader()) { |
| AddLoop(block->GetLoopInformation()); |
| } |
| } |
| |
| // Traverse the loop hierarchy inner-to-outer and optimize. Traversal can use |
| // temporary data structures using the phase-local allocator. All new HIR |
| // should use the global allocator. |
| if (top_loop_ != nullptr) { |
| ScopedArenaSet<HInstruction*> iset(loop_allocator_->Adapter(kArenaAllocLoopOptimization)); |
| ScopedArenaSafeMap<HInstruction*, HInstruction*> reds( |
| std::less<HInstruction*>(), loop_allocator_->Adapter(kArenaAllocLoopOptimization)); |
| ScopedArenaSet<ArrayReference> refs(loop_allocator_->Adapter(kArenaAllocLoopOptimization)); |
| ScopedArenaSafeMap<HInstruction*, HInstruction*> map( |
| std::less<HInstruction*>(), loop_allocator_->Adapter(kArenaAllocLoopOptimization)); |
| ScopedArenaSafeMap<HInstruction*, HInstruction*> perm( |
| std::less<HInstruction*>(), loop_allocator_->Adapter(kArenaAllocLoopOptimization)); |
| // Attach. |
| iset_ = &iset; |
| reductions_ = &reds; |
| vector_refs_ = &refs; |
| vector_map_ = ↦ |
| vector_permanent_map_ = &perm; |
| // Traverse. |
| didLoopOpt = TraverseLoopsInnerToOuter(top_loop_); |
| // Detach. |
| iset_ = nullptr; |
| reductions_ = nullptr; |
| vector_refs_ = nullptr; |
| vector_map_ = nullptr; |
| vector_permanent_map_ = nullptr; |
| } |
| return didLoopOpt; |
| } |
| |
| void HLoopOptimization::AddLoop(HLoopInformation* loop_info) { |
| DCHECK(loop_info != nullptr); |
| LoopNode* node = new (loop_allocator_) LoopNode(loop_info); |
| if (last_loop_ == nullptr) { |
| // First loop. |
| DCHECK(top_loop_ == nullptr); |
| last_loop_ = top_loop_ = node; |
| } else if (loop_info->IsIn(*last_loop_->loop_info)) { |
| // Inner loop. |
| node->outer = last_loop_; |
| DCHECK(last_loop_->inner == nullptr); |
| last_loop_ = last_loop_->inner = node; |
| } else { |
| // Subsequent loop. |
| while (last_loop_->outer != nullptr && !loop_info->IsIn(*last_loop_->outer->loop_info)) { |
| last_loop_ = last_loop_->outer; |
| } |
| node->outer = last_loop_->outer; |
| node->previous = last_loop_; |
| DCHECK(last_loop_->next == nullptr); |
| last_loop_ = last_loop_->next = node; |
| } |
| } |
| |
| void HLoopOptimization::RemoveLoop(LoopNode* node) { |
| DCHECK(node != nullptr); |
| DCHECK(node->inner == nullptr); |
| if (node->previous != nullptr) { |
| // Within sequence. |
| node->previous->next = node->next; |
| if (node->next != nullptr) { |
| node->next->previous = node->previous; |
| } |
| } else { |
| // First of sequence. |
| if (node->outer != nullptr) { |
| node->outer->inner = node->next; |
| } else { |
| top_loop_ = node->next; |
| } |
| if (node->next != nullptr) { |
| node->next->outer = node->outer; |
| node->next->previous = nullptr; |
| } |
| } |
| } |
| |
| bool HLoopOptimization::TraverseLoopsInnerToOuter(LoopNode* node) { |
| bool changed = false; |
| for ( ; node != nullptr; node = node->next) { |
| // Visit inner loops first. Recompute induction information for this |
| // loop if the induction of any inner loop has changed. |
| if (TraverseLoopsInnerToOuter(node->inner)) { |
| induction_range_.ReVisit(node->loop_info); |
| changed = true; |
| } |
| // Repeat simplifications in the loop-body until no more changes occur. |
| // Note that since each simplification consists of eliminating code (without |
| // introducing new code), this process is always finite. |
| do { |
| simplified_ = false; |
| SimplifyInduction(node); |
| SimplifyBlocks(node); |
| changed = simplified_ || changed; |
| } while (simplified_); |
| // Optimize inner loop. |
| if (node->inner == nullptr) { |
| changed = OptimizeInnerLoop(node) || changed; |
| } |
| } |
| return changed; |
| } |
| |
| // |
| // Optimization. |
| // |
| |
| void HLoopOptimization::SimplifyInduction(LoopNode* node) { |
| HBasicBlock* header = node->loop_info->GetHeader(); |
| HBasicBlock* preheader = node->loop_info->GetPreHeader(); |
| // Scan the phis in the header to find opportunities to simplify an induction |
| // cycle that is only used outside the loop. Replace these uses, if any, with |
| // the last value and remove the induction cycle. |
| // Examples: for (int i = 0; x != null; i++) { .... no i .... } |
| // for (int i = 0; i < 10; i++, k++) { .... no k .... } return k; |
| for (HInstructionIterator it(header->GetPhis()); !it.Done(); it.Advance()) { |
| HPhi* phi = it.Current()->AsPhi(); |
| if (TrySetPhiInduction(phi, /*restrict_uses*/ true) && |
| TryAssignLastValue(node->loop_info, phi, preheader, /*collect_loop_uses*/ false)) { |
| // Note that it's ok to have replaced uses after the loop with the last value, without |
| // being able to remove the cycle. Environment uses (which are the reason we may not be |
| // able to remove the cycle) within the loop will still hold the right value. We must |
| // have tried first, however, to replace outside uses. |
| if (CanRemoveCycle()) { |
| simplified_ = true; |
| for (HInstruction* i : *iset_) { |
| RemoveFromCycle(i); |
| } |
| DCHECK(CheckInductionSetFullyRemoved(iset_)); |
| } |
| } |
| } |
| } |
| |
| void HLoopOptimization::SimplifyBlocks(LoopNode* node) { |
| // Iterate over all basic blocks in the loop-body. |
| for (HBlocksInLoopIterator it(*node->loop_info); !it.Done(); it.Advance()) { |
| HBasicBlock* block = it.Current(); |
| // Remove dead instructions from the loop-body. |
| RemoveDeadInstructions(block->GetPhis()); |
| RemoveDeadInstructions(block->GetInstructions()); |
| // Remove trivial control flow blocks from the loop-body. |
| if (block->GetPredecessors().size() == 1 && |
| block->GetSuccessors().size() == 1 && |
| block->GetSingleSuccessor()->GetPredecessors().size() == 1) { |
| simplified_ = true; |
| block->MergeWith(block->GetSingleSuccessor()); |
| } else if (block->GetSuccessors().size() == 2) { |
| // Trivial if block can be bypassed to either branch. |
| HBasicBlock* succ0 = block->GetSuccessors()[0]; |
| HBasicBlock* succ1 = block->GetSuccessors()[1]; |
| HBasicBlock* meet0 = nullptr; |
| HBasicBlock* meet1 = nullptr; |
| if (succ0 != succ1 && |
| IsGotoBlock(succ0, &meet0) && |
| IsGotoBlock(succ1, &meet1) && |
| meet0 == meet1 && // meets again |
| meet0 != block && // no self-loop |
| meet0->GetPhis().IsEmpty()) { // not used for merging |
| simplified_ = true; |
| succ0->DisconnectAndDelete(); |
| if (block->Dominates(meet0)) { |
| block->RemoveDominatedBlock(meet0); |
| succ1->AddDominatedBlock(meet0); |
| meet0->SetDominator(succ1); |
| } |
| } |
| } |
| } |
| } |
| |
| bool HLoopOptimization::TryOptimizeInnerLoopFinite(LoopNode* node) { |
| HBasicBlock* header = node->loop_info->GetHeader(); |
| HBasicBlock* preheader = node->loop_info->GetPreHeader(); |
| // Ensure loop header logic is finite. |
| int64_t trip_count = 0; |
| if (!induction_range_.IsFinite(node->loop_info, &trip_count)) { |
| return false; |
| } |
| // Ensure there is only a single loop-body (besides the header). |
| HBasicBlock* body = nullptr; |
| for (HBlocksInLoopIterator it(*node->loop_info); !it.Done(); it.Advance()) { |
| if (it.Current() != header) { |
| if (body != nullptr) { |
| return false; |
| } |
| body = it.Current(); |
| } |
| } |
| CHECK(body != nullptr); |
| // Ensure there is only a single exit point. |
| if (header->GetSuccessors().size() != 2) { |
| return false; |
| } |
| HBasicBlock* exit = (header->GetSuccessors()[0] == body) |
| ? header->GetSuccessors()[1] |
| : header->GetSuccessors()[0]; |
| // Ensure exit can only be reached by exiting loop. |
| if (exit->GetPredecessors().size() != 1) { |
| return false; |
| } |
| // Detect either an empty loop (no side effects other than plain iteration) or |
| // a trivial loop (just iterating once). Replace subsequent index uses, if any, |
| // with the last value and remove the loop, possibly after unrolling its body. |
| HPhi* main_phi = nullptr; |
| if (TrySetSimpleLoopHeader(header, &main_phi)) { |
| bool is_empty = IsEmptyBody(body); |
| if (reductions_->empty() && // TODO: possible with some effort |
| (is_empty || trip_count == 1) && |
| TryAssignLastValue(node->loop_info, main_phi, preheader, /*collect_loop_uses*/ true)) { |
| if (!is_empty) { |
| // Unroll the loop-body, which sees initial value of the index. |
| main_phi->ReplaceWith(main_phi->InputAt(0)); |
| preheader->MergeInstructionsWith(body); |
| } |
| body->DisconnectAndDelete(); |
| exit->RemovePredecessor(header); |
| header->RemoveSuccessor(exit); |
| header->RemoveDominatedBlock(exit); |
| header->DisconnectAndDelete(); |
| preheader->AddSuccessor(exit); |
| preheader->AddInstruction(new (global_allocator_) HGoto()); |
| preheader->AddDominatedBlock(exit); |
| exit->SetDominator(preheader); |
| RemoveLoop(node); // update hierarchy |
| return true; |
| } |
| } |
| // Vectorize loop, if possible and valid. |
| if (kEnableVectorization && |
| TrySetSimpleLoopHeader(header, &main_phi) && |
| ShouldVectorize(node, body, trip_count) && |
| TryAssignLastValue(node->loop_info, main_phi, preheader, /*collect_loop_uses*/ true)) { |
| Vectorize(node, body, exit, trip_count); |
| graph_->SetHasSIMD(true); // flag SIMD usage |
| MaybeRecordStat(stats_, MethodCompilationStat::kLoopVectorized); |
| return true; |
| } |
| return false; |
| } |
| |
| bool HLoopOptimization::OptimizeInnerLoop(LoopNode* node) { |
| return TryOptimizeInnerLoopFinite(node) || |
| TryPeelingForLoopInvariantExitsElimination(node) || |
| TryUnrollingForBranchPenaltyReduction(node); |
| } |
| |
| |
| |
| // |
| // Loop unrolling: generic part methods. |
| // |
| |
| bool HLoopOptimization::TryUnrollingForBranchPenaltyReduction(LoopNode* node) { |
| // Don't run peeling/unrolling if compiler_driver_ is nullptr (i.e., running under tests) |
| // as InstructionSet is needed. |
| if (!kEnableScalarPeelingUnrolling || compiler_driver_ == nullptr) { |
| return false; |
| } |
| |
| HLoopInformation* loop_info = node->loop_info; |
| int64_t trip_count = 0; |
| // Only unroll loops with a known tripcount. |
| if (!induction_range_.HasKnownTripCount(loop_info, &trip_count)) { |
| return false; |
| } |
| |
| uint32_t unrolling_factor = arch_loop_helper_->GetScalarUnrollingFactor(loop_info, trip_count); |
| if (unrolling_factor == kNoUnrollingFactor) { |
| return false; |
| } |
| |
| LoopAnalysisInfo loop_analysis_info(loop_info); |
| LoopAnalysis::CalculateLoopBasicProperties(loop_info, &loop_analysis_info); |
| |
| // Check "IsLoopClonable" last as it can be time-consuming. |
| if (arch_loop_helper_->IsLoopTooBigForScalarPeelingUnrolling(&loop_analysis_info) || |
| (loop_analysis_info.GetNumberOfExits() > 1) || |
| loop_analysis_info.HasInstructionsPreventingScalarUnrolling() || |
| !PeelUnrollHelper::IsLoopClonable(loop_info)) { |
| return false; |
| } |
| |
| // TODO: support other unrolling factors. |
| DCHECK_EQ(unrolling_factor, 2u); |
| |
| // Perform unrolling. |
| PeelUnrollSimpleHelper helper(loop_info); |
| helper.DoUnrolling(); |
| |
| // Remove the redundant loop check after unrolling. |
| HIf* copy_hif = |
| helper.GetBasicBlockMap()->Get(loop_info->GetHeader())->GetLastInstruction()->AsIf(); |
| int32_t constant = loop_info->Contains(*copy_hif->IfTrueSuccessor()) ? 1 : 0; |
| copy_hif->ReplaceInput(graph_->GetIntConstant(constant), 0u); |
| |
| return true; |
| } |
| |
| bool HLoopOptimization::TryPeelingForLoopInvariantExitsElimination(LoopNode* node) { |
| // Don't run peeling/unrolling if compiler_driver_ is nullptr (i.e., running under tests) |
| // as InstructionSet is needed. |
| if (!kEnableScalarPeelingUnrolling || compiler_driver_ == nullptr) { |
| return false; |
| } |
| |
| HLoopInformation* loop_info = node->loop_info; |
| // Check 'IsLoopClonable' the last as it might be time-consuming. |
| if (!arch_loop_helper_->IsLoopPeelingEnabled()) { |
| return false; |
| } |
| |
| LoopAnalysisInfo loop_analysis_info(loop_info); |
| LoopAnalysis::CalculateLoopBasicProperties(loop_info, &loop_analysis_info); |
| |
| // Check "IsLoopClonable" last as it can be time-consuming. |
| if (arch_loop_helper_->IsLoopTooBigForScalarPeelingUnrolling(&loop_analysis_info) || |
| loop_analysis_info.HasInstructionsPreventingScalarPeeling() || |
| !LoopAnalysis::HasLoopAtLeastOneInvariantExit(loop_info) || |
| !PeelUnrollHelper::IsLoopClonable(loop_info)) { |
| return false; |
| } |
| |
| // Perform peeling. |
| PeelUnrollSimpleHelper helper(loop_info); |
| helper.DoPeeling(); |
| |
| const SuperblockCloner::HInstructionMap* hir_map = helper.GetInstructionMap(); |
| for (auto entry : *hir_map) { |
| HInstruction* copy = entry.second; |
| if (copy->IsIf()) { |
| TryToEvaluateIfCondition(copy->AsIf(), graph_); |
| } |
| } |
| |
| return true; |
| } |
| |
| // |
| // Loop vectorization. The implementation is based on the book by Aart J.C. Bik: |
| // "The Software Vectorization Handbook. Applying Multimedia Extensions for Maximum Performance." |
| // Intel Press, June, 2004 (http://www.aartbik.com/). |
| // |
| |
| bool HLoopOptimization::ShouldVectorize(LoopNode* node, HBasicBlock* block, int64_t trip_count) { |
| // Reset vector bookkeeping. |
| vector_length_ = 0; |
| vector_refs_->clear(); |
| vector_static_peeling_factor_ = 0; |
| vector_dynamic_peeling_candidate_ = nullptr; |
| vector_runtime_test_a_ = |
| vector_runtime_test_b_ = nullptr; |
| |
| // Phis in the loop-body prevent vectorization. |
| if (!block->GetPhis().IsEmpty()) { |
| return false; |
| } |
| |
| // Scan the loop-body, starting a right-hand-side tree traversal at each left-hand-side |
| // occurrence, which allows passing down attributes down the use tree. |
| for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) { |
| if (!VectorizeDef(node, it.Current(), /*generate_code*/ false)) { |
| return false; // failure to vectorize a left-hand-side |
| } |
| } |
| |
| // Prepare alignment analysis: |
| // (1) find desired alignment (SIMD vector size in bytes). |
| // (2) initialize static loop peeling votes (peeling factor that will |
| // make one particular reference aligned), never to exceed (1). |
| // (3) variable to record how many references share same alignment. |
| // (4) variable to record suitable candidate for dynamic loop peeling. |
| uint32_t desired_alignment = GetVectorSizeInBytes(); |
| DCHECK_LE(desired_alignment, 16u); |
| uint32_t peeling_votes[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; |
| uint32_t max_num_same_alignment = 0; |
| const ArrayReference* peeling_candidate = nullptr; |
| |
| // Data dependence analysis. Find each pair of references with same type, where |
| // at least one is a write. Each such pair denotes a possible data dependence. |
| // This analysis exploits the property that differently typed arrays cannot be |
| // aliased, as well as the property that references either point to the same |
| // array or to two completely disjoint arrays, i.e., no partial aliasing. |
| // Other than a few simply heuristics, no detailed subscript analysis is done. |
| // The scan over references also prepares finding a suitable alignment strategy. |
| for (auto i = vector_refs_->begin(); i != vector_refs_->end(); ++i) { |
| uint32_t num_same_alignment = 0; |
| // Scan over all next references. |
| for (auto j = i; ++j != vector_refs_->end(); ) { |
| if (i->type == j->type && (i->lhs || j->lhs)) { |
| // Found same-typed a[i+x] vs. b[i+y], where at least one is a write. |
| HInstruction* a = i->base; |
| HInstruction* b = j->base; |
| HInstruction* x = i->offset; |
| HInstruction* y = j->offset; |
| if (a == b) { |
| // Found a[i+x] vs. a[i+y]. Accept if x == y (loop-independent data dependence). |
| // Conservatively assume a loop-carried data dependence otherwise, and reject. |
| if (x != y) { |
| return false; |
| } |
| // Count the number of references that have the same alignment (since |
| // base and offset are the same) and where at least one is a write, so |
| // e.g. a[i] = a[i] + b[i] counts a[i] but not b[i]). |
| num_same_alignment++; |
| } else { |
| // Found a[i+x] vs. b[i+y]. Accept if x == y (at worst loop-independent data dependence). |
| // Conservatively assume a potential loop-carried data dependence otherwise, avoided by |
| // generating an explicit a != b disambiguation runtime test on the two references. |
| if (x != y) { |
| // To avoid excessive overhead, we only accept one a != b test. |
| if (vector_runtime_test_a_ == nullptr) { |
| // First test found. |
| vector_runtime_test_a_ = a; |
| vector_runtime_test_b_ = b; |
| } else if ((vector_runtime_test_a_ != a || vector_runtime_test_b_ != b) && |
| (vector_runtime_test_a_ != b || vector_runtime_test_b_ != a)) { |
| return false; // second test would be needed |
| } |
| } |
| } |
| } |
| } |
| // Update information for finding suitable alignment strategy: |
| // (1) update votes for static loop peeling, |
| // (2) update suitable candidate for dynamic loop peeling. |
| Alignment alignment = ComputeAlignment(i->offset, i->type, i->is_string_char_at); |
| if (alignment.Base() >= desired_alignment) { |
| // If the array/string object has a known, sufficient alignment, use the |
| // initial offset to compute the static loop peeling vote (this always |
| // works, since elements have natural alignment). |
| uint32_t offset = alignment.Offset() & (desired_alignment - 1u); |
| uint32_t vote = (offset == 0) |
| ? 0 |
| : ((desired_alignment - offset) >> DataType::SizeShift(i->type)); |
| DCHECK_LT(vote, 16u); |
| ++peeling_votes[vote]; |
| } else if (BaseAlignment() >= desired_alignment && |
| num_same_alignment > max_num_same_alignment) { |
| // Otherwise, if the array/string object has a known, sufficient alignment |
| // for just the base but with an unknown offset, record the candidate with |
| // the most occurrences for dynamic loop peeling (again, the peeling always |
| // works, since elements have natural alignment). |
| max_num_same_alignment = num_same_alignment; |
| peeling_candidate = &(*i); |
| } |
| } // for i |
| |
| // Find a suitable alignment strategy. |
| SetAlignmentStrategy(peeling_votes, peeling_candidate); |
| |
| // Does vectorization seem profitable? |
| if (!IsVectorizationProfitable(trip_count)) { |
| return false; |
| } |
| |
| // Success! |
| return true; |
| } |
| |
| void HLoopOptimization::Vectorize(LoopNode* node, |
| HBasicBlock* block, |
| HBasicBlock* exit, |
| int64_t trip_count) { |
| HBasicBlock* header = node->loop_info->GetHeader(); |
| HBasicBlock* preheader = node->loop_info->GetPreHeader(); |
| |
| // Pick a loop unrolling factor for the vector loop. |
| uint32_t unroll = arch_loop_helper_->GetSIMDUnrollingFactor( |
| block, trip_count, MaxNumberPeeled(), vector_length_); |
| uint32_t chunk = vector_length_ * unroll; |
| |
| DCHECK(trip_count == 0 || (trip_count >= MaxNumberPeeled() + chunk)); |
| |
| // A cleanup loop is needed, at least, for any unknown trip count or |
| // for a known trip count with remainder iterations after vectorization. |
| bool needs_cleanup = trip_count == 0 || |
| ((trip_count - vector_static_peeling_factor_) % chunk) != 0; |
| |
| // Adjust vector bookkeeping. |
| HPhi* main_phi = nullptr; |
| bool is_simple_loop_header = TrySetSimpleLoopHeader(header, &main_phi); // refills sets |
| DCHECK(is_simple_loop_header); |
| vector_header_ = header; |
| vector_body_ = block; |
| |
| // Loop induction type. |
| DataType::Type induc_type = main_phi->GetType(); |
| DCHECK(induc_type == DataType::Type::kInt32 || induc_type == DataType::Type::kInt64) |
| << induc_type; |
| |
| // Generate the trip count for static or dynamic loop peeling, if needed: |
| // ptc = <peeling factor>; |
| HInstruction* ptc = nullptr; |
| if (vector_static_peeling_factor_ != 0) { |
| // Static loop peeling for SIMD alignment (using the most suitable |
| // fixed peeling factor found during prior alignment analysis). |
| DCHECK(vector_dynamic_peeling_candidate_ == nullptr); |
| ptc = graph_->GetConstant(induc_type, vector_static_peeling_factor_); |
| } else if (vector_dynamic_peeling_candidate_ != nullptr) { |
| // Dynamic loop peeling for SIMD alignment (using the most suitable |
| // candidate found during prior alignment analysis): |
| // rem = offset % ALIGN; // adjusted as #elements |
| // ptc = rem == 0 ? 0 : (ALIGN - rem); |
| uint32_t shift = DataType::SizeShift(vector_dynamic_peeling_candidate_->type); |
| uint32_t align = GetVectorSizeInBytes() >> shift; |
| uint32_t hidden_offset = HiddenOffset(vector_dynamic_peeling_candidate_->type, |
| vector_dynamic_peeling_candidate_->is_string_char_at); |
| HInstruction* adjusted_offset = graph_->GetConstant(induc_type, hidden_offset >> shift); |
| HInstruction* offset = Insert(preheader, new (global_allocator_) HAdd( |
| induc_type, vector_dynamic_peeling_candidate_->offset, adjusted_offset)); |
| HInstruction* rem = Insert(preheader, new (global_allocator_) HAnd( |
| induc_type, offset, graph_->GetConstant(induc_type, align - 1u))); |
| HInstruction* sub = Insert(preheader, new (global_allocator_) HSub( |
| induc_type, graph_->GetConstant(induc_type, align), rem)); |
| HInstruction* cond = Insert(preheader, new (global_allocator_) HEqual( |
| rem, graph_->GetConstant(induc_type, 0))); |
| ptc = Insert(preheader, new (global_allocator_) HSelect( |
| cond, graph_->GetConstant(induc_type, 0), sub, kNoDexPc)); |
| needs_cleanup = true; // don't know the exact amount |
| } |
| |
| // Generate loop control: |
| // stc = <trip-count>; |
| // ptc = min(stc, ptc); |
| // vtc = stc - (stc - ptc) % chunk; |
| // i = 0; |
| HInstruction* stc = induction_range_.GenerateTripCount(node->loop_info, graph_, preheader); |
| HInstruction* vtc = stc; |
| if (needs_cleanup) { |
| DCHECK(IsPowerOfTwo(chunk)); |
| HInstruction* diff = stc; |
| if (ptc != nullptr) { |
| if (trip_count == 0) { |
| HInstruction* cond = Insert(preheader, new (global_allocator_) HAboveOrEqual(stc, ptc)); |
| ptc = Insert(preheader, new (global_allocator_) HSelect(cond, ptc, stc, kNoDexPc)); |
| } |
| diff = Insert(preheader, new (global_allocator_) HSub(induc_type, stc, ptc)); |
| } |
| HInstruction* rem = Insert( |
| preheader, new (global_allocator_) HAnd(induc_type, |
| diff, |
| graph_->GetConstant(induc_type, chunk - 1))); |
| vtc = Insert(preheader, new (global_allocator_) HSub(induc_type, stc, rem)); |
| } |
| vector_index_ = graph_->GetConstant(induc_type, 0); |
| |
| // Generate runtime disambiguation test: |
| // vtc = a != b ? vtc : 0; |
| if (vector_runtime_test_a_ != nullptr) { |
| HInstruction* rt = Insert( |
| preheader, |
| new (global_allocator_) HNotEqual(vector_runtime_test_a_, vector_runtime_test_b_)); |
| vtc = Insert(preheader, |
| new (global_allocator_) |
| HSelect(rt, vtc, graph_->GetConstant(induc_type, 0), kNoDexPc)); |
| needs_cleanup = true; |
| } |
| |
| // Generate alignment peeling loop, if needed: |
| // for ( ; i < ptc; i += 1) |
| // <loop-body> |
| // |
| // NOTE: The alignment forced by the peeling loop is preserved even if data is |
| // moved around during suspend checks, since all analysis was based on |
| // nothing more than the Android runtime alignment conventions. |
| if (ptc != nullptr) { |
| vector_mode_ = kSequential; |
| GenerateNewLoop(node, |
| block, |
| graph_->TransformLoopForVectorization(vector_header_, vector_body_, exit), |
| vector_index_, |
| ptc, |
| graph_->GetConstant(induc_type, 1), |
| kNoUnrollingFactor); |
| } |
| |
| // Generate vector loop, possibly further unrolled: |
| // for ( ; i < vtc; i += chunk) |
| // <vectorized-loop-body> |
| vector_mode_ = kVector; |
| GenerateNewLoop(node, |
| block, |
| graph_->TransformLoopForVectorization(vector_header_, vector_body_, exit), |
| vector_index_, |
| vtc, |
| graph_->GetConstant(induc_type, vector_length_), // increment per unroll |
| unroll); |
| HLoopInformation* vloop = vector_header_->GetLoopInformation(); |
| |
| // Generate cleanup loop, if needed: |
| // for ( ; i < stc; i += 1) |
| // <loop-body> |
| if (needs_cleanup) { |
| vector_mode_ = kSequential; |
| GenerateNewLoop(node, |
| block, |
| graph_->TransformLoopForVectorization(vector_header_, vector_body_, exit), |
| vector_index_, |
| stc, |
| graph_->GetConstant(induc_type, 1), |
| kNoUnrollingFactor); |
| } |
| |
| // Link reductions to their final uses. |
| for (auto i = reductions_->begin(); i != reductions_->end(); ++i) { |
| if (i->first->IsPhi()) { |
| HInstruction* phi = i->first; |
| HInstruction* repl = ReduceAndExtractIfNeeded(i->second); |
| // Deal with regular uses. |
| for (const HUseListNode<HInstruction*>& use : phi->GetUses()) { |
| induction_range_.Replace(use.GetUser(), phi, repl); // update induction use |
| } |
| phi->ReplaceWith(repl); |
| } |
| } |
| |
| // Remove the original loop by disconnecting the body block |
| // and removing all instructions from the header. |
| block->DisconnectAndDelete(); |
| while (!header->GetFirstInstruction()->IsGoto()) { |
| header->RemoveInstruction(header->GetFirstInstruction()); |
| } |
| |
| // Update loop hierarchy: the old header now resides in the same outer loop |
| // as the old preheader. Note that we don't bother putting sequential |
| // loops back in the hierarchy at this point. |
| header->SetLoopInformation(preheader->GetLoopInformation()); // outward |
| node->loop_info = vloop; |
| } |
| |
| void HLoopOptimization::GenerateNewLoop(LoopNode* node, |
| HBasicBlock* block, |
| HBasicBlock* new_preheader, |
| HInstruction* lo, |
| HInstruction* hi, |
| HInstruction* step, |
| uint32_t unroll) { |
| DCHECK(unroll == 1 || vector_mode_ == kVector); |
| DataType::Type induc_type = lo->GetType(); |
| // Prepare new loop. |
| vector_preheader_ = new_preheader, |
| vector_header_ = vector_preheader_->GetSingleSuccessor(); |
| vector_body_ = vector_header_->GetSuccessors()[1]; |
| HPhi* phi = new (global_allocator_) HPhi(global_allocator_, |
| kNoRegNumber, |
| 0, |
| HPhi::ToPhiType(induc_type)); |
| // Generate header and prepare body. |
| // for (i = lo; i < hi; i += step) |
| // <loop-body> |
| HInstruction* cond = new (global_allocator_) HAboveOrEqual(phi, hi); |
| vector_header_->AddPhi(phi); |
| vector_header_->AddInstruction(cond); |
| vector_header_->AddInstruction(new (global_allocator_) HIf(cond)); |
| vector_index_ = phi; |
| vector_permanent_map_->clear(); // preserved over unrolling |
| for (uint32_t u = 0; u < unroll; u++) { |
| // Generate instruction map. |
| vector_map_->clear(); |
| for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) { |
| bool vectorized_def = VectorizeDef(node, it.Current(), /*generate_code*/ true); |
| DCHECK(vectorized_def); |
| } |
| // Generate body from the instruction map, but in original program order. |
| HEnvironment* env = vector_header_->GetFirstInstruction()->GetEnvironment(); |
| for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) { |
| auto i = vector_map_->find(it.Current()); |
| if (i != vector_map_->end() && !i->second->IsInBlock()) { |
| Insert(vector_body_, i->second); |
| // Deal with instructions that need an environment, such as the scalar intrinsics. |
| if (i->second->NeedsEnvironment()) { |
| i->second->CopyEnvironmentFromWithLoopPhiAdjustment(env, vector_header_); |
| } |
| } |
| } |
| // Generate the induction. |
| vector_index_ = new (global_allocator_) HAdd(induc_type, vector_index_, step); |
| Insert(vector_body_, vector_index_); |
| } |
| // Finalize phi inputs for the reductions (if any). |
| for (auto i = reductions_->begin(); i != reductions_->end(); ++i) { |
| if (!i->first->IsPhi()) { |
| DCHECK(i->second->IsPhi()); |
| GenerateVecReductionPhiInputs(i->second->AsPhi(), i->first); |
| } |
| } |
| // Finalize phi inputs for the loop index. |
| phi->AddInput(lo); |
| phi->AddInput(vector_index_); |
| vector_index_ = phi; |
| } |
| |
| bool HLoopOptimization::VectorizeDef(LoopNode* node, |
| HInstruction* instruction, |
| bool generate_code) { |
| // Accept a left-hand-side array base[index] for |
| // (1) supported vector type, |
| // (2) loop-invariant base, |
| // (3) unit stride index, |
| // (4) vectorizable right-hand-side value. |
| uint64_t restrictions = kNone; |
| if (instruction->IsArraySet()) { |
| DataType::Type type = instruction->AsArraySet()->GetComponentType(); |
| HInstruction* base = instruction->InputAt(0); |
| HInstruction* index = instruction->InputAt(1); |
| HInstruction* value = instruction->InputAt(2); |
| HInstruction* offset = nullptr; |
| // For narrow types, explicit type conversion may have been |
| // optimized way, so set the no hi bits restriction here. |
| if (DataType::Size(type) <= 2) { |
| restrictions |= kNoHiBits; |
| } |
| if (TrySetVectorType(type, &restrictions) && |
| node->loop_info->IsDefinedOutOfTheLoop(base) && |
| induction_range_.IsUnitStride(instruction, index, graph_, &offset) && |
| VectorizeUse(node, value, generate_code, type, restrictions)) { |
| if (generate_code) { |
| GenerateVecSub(index, offset); |
| GenerateVecMem(instruction, vector_map_->Get(index), vector_map_->Get(value), offset, type); |
| } else { |
| vector_refs_->insert(ArrayReference(base, offset, type, /*lhs*/ true)); |
| } |
| return true; |
| } |
| return false; |
| } |
| // Accept a left-hand-side reduction for |
| // (1) supported vector type, |
| // (2) vectorizable right-hand-side value. |
| auto redit = reductions_->find(instruction); |
| if (redit != reductions_->end()) { |
| DataType::Type type = instruction->GetType(); |
| // Recognize SAD idiom or direct reduction. |
| if (VectorizeSADIdiom(node, instruction, generate_code, type, restrictions) || |
| (TrySetVectorType(type, &restrictions) && |
| VectorizeUse(node, instruction, generate_code, type, restrictions))) { |
| if (generate_code) { |
| HInstruction* new_red = vector_map_->Get(instruction); |
| vector_permanent_map_->Put(new_red, vector_map_->Get(redit->second)); |
| vector_permanent_map_->Overwrite(redit->second, new_red); |
| } |
| return true; |
| } |
| return false; |
| } |
| // Branch back okay. |
| if (instruction->IsGoto()) { |
| return true; |
| } |
| // Otherwise accept only expressions with no effects outside the immediate loop-body. |
| // Note that actual uses are inspected during right-hand-side tree traversal. |
| return !IsUsedOutsideLoop(node->loop_info, instruction) && !instruction->DoesAnyWrite(); |
| } |
| |
| bool HLoopOptimization::VectorizeUse(LoopNode* node, |
| HInstruction* instruction, |
| bool generate_code, |
| DataType::Type type, |
| uint64_t restrictions) { |
| // Accept anything for which code has already been generated. |
| if (generate_code) { |
| if (vector_map_->find(instruction) != vector_map_->end()) { |
| return true; |
| } |
| } |
| // Continue the right-hand-side tree traversal, passing in proper |
| // types and vector restrictions along the way. During code generation, |
| // all new nodes are drawn from the global allocator. |
| if (node->loop_info->IsDefinedOutOfTheLoop(instruction)) { |
| // Accept invariant use, using scalar expansion. |
| if (generate_code) { |
| GenerateVecInv(instruction, type); |
| } |
| return true; |
| } else if (instruction->IsArrayGet()) { |
| // Deal with vector restrictions. |
| bool is_string_char_at = instruction->AsArrayGet()->IsStringCharAt(); |
| if (is_string_char_at && HasVectorRestrictions(restrictions, kNoStringCharAt)) { |
| return false; |
| } |
| // Accept a right-hand-side array base[index] for |
| // (1) matching vector type (exact match or signed/unsigned integral type of the same size), |
| // (2) loop-invariant base, |
| // (3) unit stride index, |
| // (4) vectorizable right-hand-side value. |
| HInstruction* base = instruction->InputAt(0); |
| HInstruction* index = instruction->InputAt(1); |
| HInstruction* offset = nullptr; |
| if (HVecOperation::ToSignedType(type) == HVecOperation::ToSignedType(instruction->GetType()) && |
| node->loop_info->IsDefinedOutOfTheLoop(base) && |
| induction_range_.IsUnitStride(instruction, index, graph_, &offset)) { |
| if (generate_code) { |
| GenerateVecSub(index, offset); |
| GenerateVecMem(instruction, vector_map_->Get(index), nullptr, offset, type); |
| } else { |
| vector_refs_->insert(ArrayReference(base, offset, type, /*lhs*/ false, is_string_char_at)); |
| } |
| return true; |
| } |
| } else if (instruction->IsPhi()) { |
| // Accept particular phi operations. |
| if (reductions_->find(instruction) != reductions_->end()) { |
| // Deal with vector restrictions. |
| if (HasVectorRestrictions(restrictions, kNoReduction)) { |
| return false; |
| } |
| // Accept a reduction. |
| if (generate_code) { |
| GenerateVecReductionPhi(instruction->AsPhi()); |
| } |
| return true; |
| } |
| // TODO: accept right-hand-side induction? |
| return false; |
| } else if (instruction->IsTypeConversion()) { |
| // Accept particular type conversions. |
| HTypeConversion* conversion = instruction->AsTypeConversion(); |
| HInstruction* opa = conversion->InputAt(0); |
| DataType::Type from = conversion->GetInputType(); |
| DataType::Type to = conversion->GetResultType(); |
| if (DataType::IsIntegralType(from) && DataType::IsIntegralType(to)) { |
| uint32_t size_vec = DataType::Size(type); |
| uint32_t size_from = DataType::Size(from); |
| uint32_t size_to = DataType::Size(to); |
| // Accept an integral conversion |
| // (1a) narrowing into vector type, "wider" operations cannot bring in higher order bits, or |
| // (1b) widening from at least vector type, and |
| // (2) vectorizable operand. |
| if ((size_to < size_from && |
| size_to == size_vec && |
| VectorizeUse(node, opa, generate_code, type, restrictions | kNoHiBits)) || |
| (size_to >= size_from && |
| size_from >= size_vec && |
| VectorizeUse(node, opa, generate_code, type, restrictions))) { |
| if (generate_code) { |
| if (vector_mode_ == kVector) { |
| vector_map_->Put(instruction, vector_map_->Get(opa)); // operand pass-through |
| } else { |
| GenerateVecOp(instruction, vector_map_->Get(opa), nullptr, type); |
| } |
| } |
| return true; |
| } |
| } else if (to == DataType::Type::kFloat32 && from == DataType::Type::kInt32) { |
| DCHECK_EQ(to, type); |
| // Accept int to float conversion for |
| // (1) supported int, |
| // (2) vectorizable operand. |
| if (TrySetVectorType(from, &restrictions) && |
| VectorizeUse(node, opa, generate_code, from, restrictions)) { |
| if (generate_code) { |
| GenerateVecOp(instruction, vector_map_->Get(opa), nullptr, type); |
| } |
| return true; |
| } |
| } |
| return false; |
| } else if (instruction->IsNeg() || instruction->IsNot() || instruction->IsBooleanNot()) { |
| // Accept unary operator for vectorizable operand. |
| HInstruction* opa = instruction->InputAt(0); |
| if (VectorizeUse(node, opa, generate_code, type, restrictions)) { |
| if (generate_code) { |
| GenerateVecOp(instruction, vector_map_->Get(opa), nullptr, type); |
| } |
| return true; |
| } |
| } else if (instruction->IsAdd() || instruction->IsSub() || |
| instruction->IsMul() || instruction->IsDiv() || |
| instruction->IsAnd() || instruction->IsOr() || instruction->IsXor()) { |
| // Deal with vector restrictions. |
| if ((instruction->IsMul() && HasVectorRestrictions(restrictions, kNoMul)) || |
| (instruction->IsDiv() && HasVectorRestrictions(restrictions, kNoDiv))) { |
| return false; |
| } |
| // Accept binary operator for vectorizable operands. |
| HInstruction* opa = instruction->InputAt(0); |
| HInstruction* opb = instruction->InputAt(1); |
| if (VectorizeUse(node, opa, generate_code, type, restrictions) && |
| VectorizeUse(node, opb, generate_code, type, restrictions)) { |
| if (generate_code) { |
| GenerateVecOp(instruction, vector_map_->Get(opa), vector_map_->Get(opb), type); |
| } |
| return true; |
| } |
| } else if (instruction->IsShl() || instruction->IsShr() || instruction->IsUShr()) { |
| // Recognize halving add idiom. |
| if (VectorizeHalvingAddIdiom(node, instruction, generate_code, type, restrictions)) { |
| return true; |
| } |
| // Deal with vector restrictions. |
| HInstruction* opa = instruction->InputAt(0); |
| HInstruction* opb = instruction->InputAt(1); |
| HInstruction* r = opa; |
| bool is_unsigned = false; |
| if ((HasVectorRestrictions(restrictions, kNoShift)) || |
| (instruction->IsShr() && HasVectorRestrictions(restrictions, kNoShr))) { |
| return false; // unsupported instruction |
| } else if (HasVectorRestrictions(restrictions, kNoHiBits)) { |
| // Shifts right need extra care to account for higher order bits. |
| // TODO: less likely shr/unsigned and ushr/signed can by flipping signess. |
| if (instruction->IsShr() && |
| (!IsNarrowerOperand(opa, type, &r, &is_unsigned) || is_unsigned)) { |
| return false; // reject, unless all operands are sign-extension narrower |
| } else if (instruction->IsUShr() && |
| (!IsNarrowerOperand(opa, type, &r, &is_unsigned) || !is_unsigned)) { |
| return false; // reject, unless all operands are zero-extension narrower |
| } |
| } |
| // Accept shift operator for vectorizable/invariant operands. |
| // TODO: accept symbolic, albeit loop invariant shift factors. |
| DCHECK(r != nullptr); |
| if (generate_code && vector_mode_ != kVector) { // de-idiom |
| r = opa; |
| } |
| int64_t distance = 0; |
| if (VectorizeUse(node, r, generate_code, type, restrictions) && |
| IsInt64AndGet(opb, /*out*/ &distance)) { |
| // Restrict shift distance to packed data type width. |
| int64_t max_distance = DataType::Size(type) * 8; |
| if (0 <= distance && distance < max_distance) { |
| if (generate_code) { |
| GenerateVecOp(instruction, vector_map_->Get(r), opb, type); |
| } |
| return true; |
| } |
| } |
| } else if (instruction->IsAbs()) { |
| // Deal with vector restrictions. |
| HInstruction* opa = instruction->InputAt(0); |
| HInstruction* r = opa; |
| bool is_unsigned = false; |
| if (HasVectorRestrictions(restrictions, kNoAbs)) { |
| return false; |
| } else if (HasVectorRestrictions(restrictions, kNoHiBits) && |
| (!IsNarrowerOperand(opa, type, &r, &is_unsigned) || is_unsigned)) { |
| return false; // reject, unless operand is sign-extension narrower |
| } |
| // Accept ABS(x) for vectorizable operand. |
| DCHECK(r != nullptr); |
| if (generate_code && vector_mode_ != kVector) { // de-idiom |
| r = opa; |
| } |
| if (VectorizeUse(node, r, generate_code, type, restrictions)) { |
| if (generate_code) { |
| GenerateVecOp(instruction, |
| vector_map_->Get(r), |
| nullptr, |
| HVecOperation::ToProperType(type, is_unsigned)); |
| } |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| uint32_t HLoopOptimization::GetVectorSizeInBytes() { |
| switch (compiler_driver_->GetInstructionSet()) { |
| case InstructionSet::kArm: |
| case InstructionSet::kThumb2: |
| return 8; // 64-bit SIMD |
| default: |
| return 16; // 128-bit SIMD |
| } |
| } |
| |
| bool HLoopOptimization::TrySetVectorType(DataType::Type type, uint64_t* restrictions) { |
| const InstructionSetFeatures* features = compiler_driver_->GetInstructionSetFeatures(); |
| switch (compiler_driver_->GetInstructionSet()) { |
| case InstructionSet::kArm: |
| case InstructionSet::kThumb2: |
| // Allow vectorization for all ARM devices, because Android assumes that |
| // ARM 32-bit always supports advanced SIMD (64-bit SIMD). |
| switch (type) { |
| case DataType::Type::kBool: |
| case DataType::Type::kUint8: |
| case DataType::Type::kInt8: |
| *restrictions |= kNoDiv | kNoReduction; |
| return TrySetVectorLength(8); |
| case DataType::Type::kUint16: |
| case DataType::Type::kInt16: |
| *restrictions |= kNoDiv | kNoStringCharAt | kNoReduction; |
| return TrySetVectorLength(4); |
| case DataType::Type::kInt32: |
| *restrictions |= kNoDiv | kNoWideSAD; |
| return TrySetVectorLength(2); |
| default: |
| break; |
| } |
| return false; |
| case InstructionSet::kArm64: |
| // Allow vectorization for all ARM devices, because Android assumes that |
| // ARMv8 AArch64 always supports advanced SIMD (128-bit SIMD). |
| switch (type) { |
| case DataType::Type::kBool: |
| case DataType::Type::kUint8: |
| case DataType::Type::kInt8: |
| *restrictions |= kNoDiv; |
| return TrySetVectorLength(16); |
| case DataType::Type::kUint16: |
| case DataType::Type::kInt16: |
| *restrictions |= kNoDiv; |
| return TrySetVectorLength(8); |
| case DataType::Type::kInt32: |
| *restrictions |= kNoDiv; |
| return TrySetVectorLength(4); |
| case DataType::Type::kInt64: |
| *restrictions |= kNoDiv | kNoMul; |
| return TrySetVectorLength(2); |
| case DataType::Type::kFloat32: |
| *restrictions |= kNoReduction; |
| return TrySetVectorLength(4); |
| case DataType::Type::kFloat64: |
| *restrictions |= kNoReduction; |
| return TrySetVectorLength(2); |
| default: |
| return false; |
| } |
| case InstructionSet::kX86: |
| case InstructionSet::kX86_64: |
| // Allow vectorization for SSE4.1-enabled X86 devices only (128-bit SIMD). |
| if (features->AsX86InstructionSetFeatures()->HasSSE4_1()) { |
| switch (type) { |
| case DataType::Type::kBool: |
| case DataType::Type::kUint8: |
| case DataType::Type::kInt8: |
| *restrictions |= |
| kNoMul | kNoDiv | kNoShift | kNoAbs | kNoSignedHAdd | kNoUnroundedHAdd | kNoSAD; |
| return TrySetVectorLength(16); |
| case DataType::Type::kUint16: |
| case DataType::Type::kInt16: |
| *restrictions |= kNoDiv | kNoAbs | kNoSignedHAdd | kNoUnroundedHAdd | kNoSAD; |
| return TrySetVectorLength(8); |
| case DataType::Type::kInt32: |
| *restrictions |= kNoDiv | kNoSAD; |
| return TrySetVectorLength(4); |
| case DataType::Type::kInt64: |
| *restrictions |= kNoMul | kNoDiv | kNoShr | kNoAbs | kNoSAD; |
| return TrySetVectorLength(2); |
| case DataType::Type::kFloat32: |
| *restrictions |= kNoReduction; |
| return TrySetVectorLength(4); |
| case DataType::Type::kFloat64: |
| *restrictions |= kNoReduction; |
| return TrySetVectorLength(2); |
| default: |
| break; |
| } // switch type |
| } |
| return false; |
| case InstructionSet::kMips: |
| if (features->AsMipsInstructionSetFeatures()->HasMsa()) { |
| switch (type) { |
| case DataType::Type::kBool: |
| case DataType::Type::kUint8: |
| case DataType::Type::kInt8: |
| *restrictions |= kNoDiv; |
| return TrySetVectorLength(16); |
| case DataType::Type::kUint16: |
| case DataType::Type::kInt16: |
| *restrictions |= kNoDiv | kNoStringCharAt; |
| return TrySetVectorLength(8); |
| case DataType::Type::kInt32: |
| *restrictions |= kNoDiv; |
| return TrySetVectorLength(4); |
| case DataType::Type::kInt64: |
| *restrictions |= kNoDiv; |
| return TrySetVectorLength(2); |
| case DataType::Type::kFloat32: |
| *restrictions |= kNoReduction; |
| return TrySetVectorLength(4); |
| case DataType::Type::kFloat64: |
| *restrictions |= kNoReduction; |
| return TrySetVectorLength(2); |
| default: |
| break; |
| } // switch type |
| } |
| return false; |
| case InstructionSet::kMips64: |
| if (features->AsMips64InstructionSetFeatures()->HasMsa()) { |
| switch (type) { |
| case DataType::Type::kBool: |
| case DataType::Type::kUint8: |
| case DataType::Type::kInt8: |
| *restrictions |= kNoDiv; |
| return TrySetVectorLength(16); |
| case DataType::Type::kUint16: |
| case DataType::Type::kInt16: |
| *restrictions |= kNoDiv | kNoStringCharAt; |
| return TrySetVectorLength(8); |
| case DataType::Type::kInt32: |
| *restrictions |= kNoDiv; |
| return TrySetVectorLength(4); |
| case DataType::Type::kInt64: |
| *restrictions |= kNoDiv; |
| return TrySetVectorLength(2); |
| case DataType::Type::kFloat32: |
| *restrictions |= kNoReduction; |
| return TrySetVectorLength(4); |
| case DataType::Type::kFloat64: |
| *restrictions |= kNoReduction; |
| return TrySetVectorLength(2); |
| default: |
| break; |
| } // switch type |
| } |
| return false; |
| default: |
| return false; |
| } // switch instruction set |
| } |
| |
| bool HLoopOptimization::TrySetVectorLength(uint32_t length) { |
| DCHECK(IsPowerOfTwo(length) && length >= 2u); |
| // First time set? |
| if (vector_length_ == 0) { |
| vector_length_ = length; |
| } |
| // Different types are acceptable within a loop-body, as long as all the corresponding vector |
| // lengths match exactly to obtain a uniform traversal through the vector iteration space |
| // (idiomatic exceptions to this rule can be handled by further unrolling sub-expressions). |
| return vector_length_ == length; |
| } |
| |
| void HLoopOptimization::GenerateVecInv(HInstruction* org, DataType::Type type) { |
| if (vector_map_->find(org) == vector_map_->end()) { |
| // In scalar code, just use a self pass-through for scalar invariants |
| // (viz. expression remains itself). |
| if (vector_mode_ == kSequential) { |
| vector_map_->Put(org, org); |
| return; |
| } |
| // In vector code, explicit scalar expansion is needed. |
| HInstruction* vector = nullptr; |
| auto it = vector_permanent_map_->find(org); |
| if (it != vector_permanent_map_->end()) { |
| vector = it->second; // reuse during unrolling |
| } else { |
| // Generates ReplicateScalar( (optional_type_conv) org ). |
| HInstruction* input = org; |
| DataType::Type input_type = input->GetType(); |
| if (type != input_type && (type == DataType::Type::kInt64 || |
| input_type == DataType::Type::kInt64)) { |
| input = Insert(vector_preheader_, |
| new (global_allocator_) HTypeConversion(type, input, kNoDexPc)); |
| } |
| vector = new (global_allocator_) |
| HVecReplicateScalar(global_allocator_, input, type, vector_length_, kNoDexPc); |
| vector_permanent_map_->Put(org, Insert(vector_preheader_, vector)); |
| } |
| vector_map_->Put(org, vector); |
| } |
| } |
| |
| void HLoopOptimization::GenerateVecSub(HInstruction* org, HInstruction* offset) { |
| if (vector_map_->find(org) == vector_map_->end()) { |
| HInstruction* subscript = vector_index_; |
| int64_t value = 0; |
| if (!IsInt64AndGet(offset, &value) || value != 0) { |
| subscript = new (global_allocator_) HAdd(DataType::Type::kInt32, subscript, offset); |
| if (org->IsPhi()) { |
| Insert(vector_body_, subscript); // lacks layout placeholder |
| } |
| } |
| vector_map_->Put(org, subscript); |
| } |
| } |
| |
| void HLoopOptimization::GenerateVecMem(HInstruction* org, |
| HInstruction* opa, |
| HInstruction* opb, |
| HInstruction* offset, |
| DataType::Type type) { |
| uint32_t dex_pc = org->GetDexPc(); |
| HInstruction* vector = nullptr; |
| if (vector_mode_ == kVector) { |
| // Vector store or load. |
| bool is_string_char_at = false; |
| HInstruction* base = org->InputAt(0); |
| if (opb != nullptr) { |
| vector = new (global_allocator_) HVecStore( |
| global_allocator_, base, opa, opb, type, org->GetSideEffects(), vector_length_, dex_pc); |
| } else { |
| is_string_char_at = org->AsArrayGet()->IsStringCharAt(); |
| vector = new (global_allocator_) HVecLoad(global_allocator_, |
| base, |
| opa, |
| type, |
| org->GetSideEffects(), |
| vector_length_, |
| is_string_char_at, |
| dex_pc); |
| } |
| // Known (forced/adjusted/original) alignment? |
| if (vector_dynamic_peeling_candidate_ != nullptr) { |
| if (vector_dynamic_peeling_candidate_->offset == offset && // TODO: diffs too? |
| DataType::Size(vector_dynamic_peeling_candidate_->type) == DataType::Size(type) && |
| vector_dynamic_peeling_candidate_->is_string_char_at == is_string_char_at) { |
| vector->AsVecMemoryOperation()->SetAlignment( // forced |
| Alignment(GetVectorSizeInBytes(), 0)); |
| } |
| } else { |
| vector->AsVecMemoryOperation()->SetAlignment( // adjusted/original |
| ComputeAlignment(offset, type, is_string_char_at, vector_static_peeling_factor_)); |
| } |
| } else { |
| // Scalar store or load. |
| DCHECK(vector_mode_ == kSequential); |
| if (opb != nullptr) { |
| DataType::Type component_type = org->AsArraySet()->GetComponentType(); |
| vector = new (global_allocator_) HArraySet( |
| org->InputAt(0), opa, opb, component_type, org->GetSideEffects(), dex_pc); |
| } else { |
| bool is_string_char_at = org->AsArrayGet()->IsStringCharAt(); |
| vector = new (global_allocator_) HArrayGet( |
| org->InputAt(0), opa, org->GetType(), org->GetSideEffects(), dex_pc, is_string_char_at); |
| } |
| } |
| vector_map_->Put(org, vector); |
| } |
| |
| void HLoopOptimization::GenerateVecReductionPhi(HPhi* phi) { |
| DCHECK(reductions_->find(phi) != reductions_->end()); |
| DCHECK(reductions_->Get(phi->InputAt(1)) == phi); |
| HInstruction* vector = nullptr; |
| if (vector_mode_ == kSequential) { |
| HPhi* new_phi = new (global_allocator_) HPhi( |
| global_allocator_, kNoRegNumber, 0, phi->GetType()); |
| vector_header_->AddPhi(new_phi); |
| vector = new_phi; |
| } else { |
| // Link vector reduction back to prior unrolled update, or a first phi. |
| auto it = vector_permanent_map_->find(phi); |
| if (it != vector_permanent_map_->end()) { |
| vector = it->second; |
| } else { |
| HPhi* new_phi = new (global_allocator_) HPhi( |
| global_allocator_, kNoRegNumber, 0, HVecOperation::kSIMDType); |
| vector_header_->AddPhi(new_phi); |
| vector = new_phi; |
| } |
| } |
| vector_map_->Put(phi, vector); |
| } |
| |
| void HLoopOptimization::GenerateVecReductionPhiInputs(HPhi* phi, HInstruction* reduction) { |
| HInstruction* new_phi = vector_map_->Get(phi); |
| HInstruction* new_init = reductions_->Get(phi); |
| HInstruction* new_red = vector_map_->Get(reduction); |
| // Link unrolled vector loop back to new phi. |
| for (; !new_phi->IsPhi(); new_phi = vector_permanent_map_->Get(new_phi)) { |
| DCHECK(new_phi->IsVecOperation()); |
| } |
| // Prepare the new initialization. |
| if (vector_mode_ == kVector) { |
| // Generate a [initial, 0, .., 0] vector for add or |
| // a [initial, initial, .., initial] vector for min/max. |
| HVecOperation* red_vector = new_red->AsVecOperation(); |
| HVecReduce::ReductionKind kind = GetReductionKind(red_vector); |
| uint32_t vector_length = red_vector->GetVectorLength(); |
| DataType::Type type = red_vector->GetPackedType(); |
| if (kind == HVecReduce::ReductionKind::kSum) { |
| new_init = Insert(vector_preheader_, |
| new (global_allocator_) HVecSetScalars(global_allocator_, |
| &new_init, |
| type, |
| vector_length, |
| 1, |
| kNoDexPc)); |
| } else { |
| new_init = Insert(vector_preheader_, |
| new (global_allocator_) HVecReplicateScalar(global_allocator_, |
| new_init, |
| type, |
| vector_length, |
| kNoDexPc)); |
| } |
| } else { |
| new_init = ReduceAndExtractIfNeeded(new_init); |
| } |
| // Set the phi inputs. |
| DCHECK(new_phi->IsPhi()); |
| new_phi->AsPhi()->AddInput(new_init); |
| new_phi->AsPhi()->AddInput(new_red); |
| // New feed value for next phi (safe mutation in iteration). |
| reductions_->find(phi)->second = new_phi; |
| } |
| |
| HInstruction* HLoopOptimization::ReduceAndExtractIfNeeded(HInstruction* instruction) { |
| if (instruction->IsPhi()) { |
| HInstruction* input = instruction->InputAt(1); |
| if (HVecOperation::ReturnsSIMDValue(input)) { |
| DCHECK(!input->IsPhi()); |
| HVecOperation* input_vector = input->AsVecOperation(); |
| uint32_t vector_length = input_vector->GetVectorLength(); |
| DataType::Type type = input_vector->GetPackedType(); |
| HVecReduce::ReductionKind kind = GetReductionKind(input_vector); |
| HBasicBlock* exit = instruction->GetBlock()->GetSuccessors()[0]; |
| // Generate a vector reduction and scalar extract |
| // x = REDUCE( [x_1, .., x_n] ) |
| // y = x_1 |
| // along the exit of the defining loop. |
| HInstruction* reduce = new (global_allocator_) HVecReduce( |
| global_allocator_, instruction, type, vector_length, kind, kNoDexPc); |
| exit->InsertInstructionBefore(reduce, exit->GetFirstInstruction()); |
| instruction = new (global_allocator_) HVecExtractScalar( |
| global_allocator_, reduce, type, vector_length, 0, kNoDexPc); |
| exit->InsertInstructionAfter(instruction, reduce); |
| } |
| } |
| return instruction; |
| } |
| |
| #define GENERATE_VEC(x, y) \ |
| if (vector_mode_ == kVector) { \ |
| vector = (x); \ |
| } else { \ |
| DCHECK(vector_mode_ == kSequential); \ |
| vector = (y); \ |
| } \ |
| break; |
| |
| void HLoopOptimization::GenerateVecOp(HInstruction* org, |
| HInstruction* opa, |
| HInstruction* opb, |
| DataType::Type type) { |
| uint32_t dex_pc = org->GetDexPc(); |
| HInstruction* vector = nullptr; |
| DataType::Type org_type = org->GetType(); |
| switch (org->GetKind()) { |
| case HInstruction::kNeg: |
| DCHECK(opb == nullptr); |
| GENERATE_VEC( |
| new (global_allocator_) HVecNeg(global_allocator_, opa, type, vector_length_, dex_pc), |
| new (global_allocator_) HNeg(org_type, opa, dex_pc)); |
| case HInstruction::kNot: |
| DCHECK(opb == nullptr); |
| GENERATE_VEC( |
| new (global_allocator_) HVecNot(global_allocator_, opa, type, vector_length_, dex_pc), |
| new (global_allocator_) HNot(org_type, opa, dex_pc)); |
| case HInstruction::kBooleanNot: |
| DCHECK(opb == nullptr); |
| GENERATE_VEC( |
| new (global_allocator_) HVecNot(global_allocator_, opa, type, vector_length_, dex_pc), |
| new (global_allocator_) HBooleanNot(opa, dex_pc)); |
| case HInstruction::kTypeConversion: |
| DCHECK(opb == nullptr); |
| GENERATE_VEC( |
| new (global_allocator_) HVecCnv(global_allocator_, opa, type, vector_length_, dex_pc), |
| new (global_allocator_) HTypeConversion(org_type, opa, dex_pc)); |
| case HInstruction::kAdd: |
| GENERATE_VEC( |
| new (global_allocator_) HVecAdd(global_allocator_, opa, opb, type, vector_length_, dex_pc), |
| new (global_allocator_) HAdd(org_type, opa, opb, dex_pc)); |
| case HInstruction::kSub: |
| GENERATE_VEC( |
| new (global_allocator_) HVecSub(global_allocator_, opa, opb, type, vector_length_, dex_pc), |
| new (global_allocator_) HSub(org_type, opa, opb, dex_pc)); |
| case HInstruction::kMul: |
| GENERATE_VEC( |
| new (global_allocator_) HVecMul(global_allocator_, opa, opb, type, vector_length_, dex_pc), |
| new (global_allocator_) HMul(org_type, opa, opb, dex_pc)); |
| case HInstruction::kDiv: |
| GENERATE_VEC( |
| new (global_allocator_) HVecDiv(global_allocator_, opa, opb, type, vector_length_, dex_pc), |
| new (global_allocator_) HDiv(org_type, opa, opb, dex_pc)); |
| case HInstruction::kAnd: |
| GENERATE_VEC( |
| new (global_allocator_) HVecAnd(global_allocator_, opa, opb, type, vector_length_, dex_pc), |
| new (global_allocator_) HAnd(org_type, opa, opb, dex_pc)); |
| case HInstruction::kOr: |
| GENERATE_VEC( |
| new (global_allocator_) HVecOr(global_allocator_, opa, opb, type, vector_length_, dex_pc), |
| new (global_allocator_) HOr(org_type, opa, opb, dex_pc)); |
| case HInstruction::kXor: |
| GENERATE_VEC( |
| new (global_allocator_) HVecXor(global_allocator_, opa, opb, type, vector_length_, dex_pc), |
| new (global_allocator_) HXor(org_type, opa, opb, dex_pc)); |
| case HInstruction::kShl: |
| GENERATE_VEC( |
| new (global_allocator_) HVecShl(global_allocator_, opa, opb, type, vector_length_, dex_pc), |
| new (global_allocator_) HShl(org_type, opa, opb, dex_pc)); |
| case HInstruction::kShr: |
| GENERATE_VEC( |
| new (global_allocator_) HVecShr(global_allocator_, opa, opb, type, vector_length_, dex_pc), |
| new (global_allocator_) HShr(org_type, opa, opb, dex_pc)); |
| case HInstruction::kUShr: |
| GENERATE_VEC( |
| new (global_allocator_) HVecUShr(global_allocator_, opa, opb, type, vector_length_, dex_pc), |
| new (global_allocator_) HUShr(org_type, opa, opb, dex_pc)); |
| case HInstruction::kAbs: |
| DCHECK(opb == nullptr); |
| GENERATE_VEC( |
| new (global_allocator_) HVecAbs(global_allocator_, opa, type, vector_length_, dex_pc), |
| new (global_allocator_) HAbs(org_type, opa, dex_pc)); |
| default: |
| break; |
| } // switch |
| CHECK(vector != nullptr) << "Unsupported SIMD operator"; |
| vector_map_->Put(org, vector); |
| } |
| |
| #undef GENERATE_VEC |
| |
| // |
| // Vectorization idioms. |
| // |
| |
| // Method recognizes the following idioms: |
| // rounding halving add (a + b + 1) >> 1 for unsigned/signed operands a, b |
| // truncated halving add (a + b) >> 1 for unsigned/signed operands a, b |
| // Provided that the operands are promoted to a wider form to do the arithmetic and |
| // then cast back to narrower form, the idioms can be mapped into efficient SIMD |
| // implementation that operates directly in narrower form (plus one extra bit). |
| // TODO: current version recognizes implicit byte/short/char widening only; |
| // explicit widening from int to long could be added later. |
| bool HLoopOptimization::VectorizeHalvingAddIdiom(LoopNode* node, |
| HInstruction* instruction, |
| bool generate_code, |
| DataType::Type type, |
| uint64_t restrictions) { |
| // Test for top level arithmetic shift right x >> 1 or logical shift right x >>> 1 |
| // (note whether the sign bit in wider precision is shifted in has no effect |
| // on the narrow precision computed by the idiom). |
| if ((instruction->IsShr() || |
| instruction->IsUShr()) && |
| IsInt64Value(instruction->InputAt(1), 1)) { |
| // Test for (a + b + c) >> 1 for optional constant c. |
| HInstruction* a = nullptr; |
| HInstruction* b = nullptr; |
| int64_t c = 0; |
| if (IsAddConst2(graph_, instruction->InputAt(0), /*out*/ &a, /*out*/ &b, /*out*/ &c)) { |
| // Accept c == 1 (rounded) or c == 0 (not rounded). |
| bool is_rounded = false; |
| if (c == 1) { |
| is_rounded = true; |
| } else if (c != 0) { |
| return false; |
| } |
| // Accept consistent zero or sign extension on operands a and b. |
| HInstruction* r = nullptr; |
| HInstruction* s = nullptr; |
| bool is_unsigned = false; |
| if (!IsNarrowerOperands(a, b, type, &r, &s, &is_unsigned)) { |
| return false; |
| } |
| // Deal with vector restrictions. |
| if ((!is_unsigned && HasVectorRestrictions(restrictions, kNoSignedHAdd)) || |
| (!is_rounded && HasVectorRestrictions(restrictions, kNoUnroundedHAdd))) { |
| return false; |
| } |
| // Accept recognized halving add for vectorizable operands. Vectorized code uses the |
| // shorthand idiomatic operation. Sequential code uses the original scalar expressions. |
| DCHECK(r != nullptr && s != nullptr); |
| if (generate_code && vector_mode_ != kVector) { // de-idiom |
| r = instruction->InputAt(0); |
| s = instruction->InputAt(1); |
| } |
| if (VectorizeUse(node, r, generate_code, type, restrictions) && |
| VectorizeUse(node, s, generate_code, type, restrictions)) { |
| if (generate_code) { |
| if (vector_mode_ == kVector) { |
| vector_map_->Put(instruction, new (global_allocator_) HVecHalvingAdd( |
| global_allocator_, |
| vector_map_->Get(r), |
| vector_map_->Get(s), |
| HVecOperation::ToProperType(type, is_unsigned), |
| vector_length_, |
| is_rounded, |
| kNoDexPc)); |
| MaybeRecordStat(stats_, MethodCompilationStat::kLoopVectorizedIdiom); |
| } else { |
| GenerateVecOp(instruction, vector_map_->Get(r), vector_map_->Get(s), type); |
| } |
| } |
| return true; |
| } |
| } |
| } |
| return false; |
| } |
| |
| // Method recognizes the following idiom: |
| // q += ABS(a - b) for signed operands a, b |
| // Provided that the operands have the same type or are promoted to a wider form. |
| // Since this may involve a vector length change, the idiom is handled by going directly |
| // to a sad-accumulate node (rather than relying combining finer grained nodes later). |
| // TODO: unsigned SAD too? |
| bool HLoopOptimization::VectorizeSADIdiom(LoopNode* node, |
| HInstruction* instruction, |
| bool generate_code, |
| DataType::Type reduction_type, |
| uint64_t restrictions) { |
| // Filter integral "q += ABS(a - b);" reduction, where ABS and SUB |
| // are done in the same precision (either int or long). |
| if (!instruction->IsAdd() || |
| (reduction_type != DataType::Type::kInt32 && reduction_type != DataType::Type::kInt64)) { |
| return false; |
| } |
| HInstruction* q = instruction->InputAt(0); |
| HInstruction* v = instruction->InputAt(1); |
| HInstruction* a = nullptr; |
| HInstruction* b = nullptr; |
| if (v->IsAbs() && |
| v->GetType() == reduction_type && |
| IsSubConst2(graph_, v->InputAt(0), /*out*/ &a, /*out*/ &b)) { |
| DCHECK(a != nullptr && b != nullptr); |
| } else { |
| return false; |
| } |
| // Accept same-type or consistent sign extension for narrower-type on operands a and b. |
| // The same-type or narrower operands are called r (a or lower) and s (b or lower). |
| // We inspect the operands carefully to pick the most suited type. |
| HInstruction* r = a; |
| HInstruction* s = b; |
| bool is_unsigned = false; |
| DataType::Type sub_type = a->GetType(); |
| if (DataType::Size(b->GetType()) < DataType::Size(sub_type)) { |
| sub_type = b->GetType(); |
| } |
| if (a->IsTypeConversion() && |
| DataType::Size(a->InputAt(0)->GetType()) < DataType::Size(sub_type)) { |
| sub_type = a->InputAt(0)->GetType(); |
| } |
| if (b->IsTypeConversion() && |
| DataType::Size(b->InputAt(0)->GetType()) < DataType::Size(sub_type)) { |
| sub_type = b->InputAt(0)->GetType(); |
| } |
| if (reduction_type != sub_type && |
| (!IsNarrowerOperands(a, b, sub_type, &r, &s, &is_unsigned) || is_unsigned)) { |
| return false; |
| } |
| // Try same/narrower type and deal with vector restrictions. |
| if (!TrySetVectorType(sub_type, &restrictions) || |
| HasVectorRestrictions(restrictions, kNoSAD) || |
| (reduction_type != sub_type && HasVectorRestrictions(restrictions, kNoWideSAD))) { |
| return false; |
| } |
| // Accept SAD idiom for vectorizable operands. Vectorized code uses the shorthand |
| // idiomatic operation. Sequential code uses the original scalar expressions. |
| DCHECK(r != nullptr && s != nullptr); |
| if (generate_code && vector_mode_ != kVector) { // de-idiom |
| r = s = v->InputAt(0); |
| } |
| if (VectorizeUse(node, q, generate_code, sub_type, restrictions) && |
| VectorizeUse(node, r, generate_code, sub_type, restrictions) && |
| VectorizeUse(node, s, generate_code, sub_type, restrictions)) { |
| if (generate_code) { |
| if (vector_mode_ == kVector) { |
| vector_map_->Put(instruction, new (global_allocator_) HVecSADAccumulate( |
| global_allocator_, |
| vector_map_->Get(q), |
| vector_map_->Get(r), |
| vector_map_->Get(s), |
| HVecOperation::ToProperType(reduction_type, is_unsigned), |
| GetOtherVL(reduction_type, sub_type, vector_length_), |
| kNoDexPc)); |
| MaybeRecordStat(stats_, MethodCompilationStat::kLoopVectorizedIdiom); |
| } else { |
| GenerateVecOp(v, vector_map_->Get(r), nullptr, reduction_type); |
| GenerateVecOp(instruction, vector_map_->Get(q), vector_map_->Get(v), reduction_type); |
| } |
| } |
| return true; |
| } |
| return false; |
| } |
| |
| // |
| // Vectorization heuristics. |
| // |
| |
| Alignment HLoopOptimization::ComputeAlignment(HInstruction* offset, |
| DataType::Type type, |
| bool is_string_char_at, |
| uint32_t peeling) { |
| // Combine the alignment and hidden offset that is guaranteed by |
| // the Android runtime with a known starting index adjusted as bytes. |
| int64_t value = 0; |
| if (IsInt64AndGet(offset, /*out*/ &value)) { |
| uint32_t start_offset = |
| HiddenOffset(type, is_string_char_at) + (value + peeling) * DataType::Size(type); |
| return Alignment(BaseAlignment(), start_offset & (BaseAlignment() - 1u)); |
| } |
| // Otherwise, the Android runtime guarantees at least natural alignment. |
| return Alignment(DataType::Size(type), 0); |
| } |
| |
| void HLoopOptimization::SetAlignmentStrategy(uint32_t peeling_votes[], |
| const ArrayReference* peeling_candidate) { |
| // Current heuristic: pick the best static loop peeling factor, if any, |
| // or otherwise use dynamic loop peeling on suggested peeling candidate. |
| uint32_t max_vote = 0; |
| for (int32_t i = 0; i < 16; i++) { |
| if (peeling_votes[i] > max_vote) { |
| max_vote = peeling_votes[i]; |
| vector_static_peeling_factor_ = i; |
| } |
| } |
| if (max_vote == 0) { |
| vector_dynamic_peeling_candidate_ = peeling_candidate; |
| } |
| } |
| |
| uint32_t HLoopOptimization::MaxNumberPeeled() { |
| if (vector_dynamic_peeling_candidate_ != nullptr) { |
| return vector_length_ - 1u; // worst-case |
| } |
| return vector_static_peeling_factor_; // known exactly |
| } |
| |
| bool HLoopOptimization::IsVectorizationProfitable(int64_t trip_count) { |
| // Current heuristic: non-empty body with sufficient number of iterations (if known). |
| // TODO: refine by looking at e.g. operation count, alignment, etc. |
| // TODO: trip count is really unsigned entity, provided the guarding test |
| // is satisfied; deal with this more carefully later |
| uint32_t max_peel = MaxNumberPeeled(); |
| if (vector_length_ == 0) { |
| return false; // nothing found |
| } else if (trip_count < 0) { |
| return false; // guard against non-taken/large |
| } else if ((0 < trip_count) && (trip_count < (vector_length_ + max_peel))) { |
| return false; // insufficient iterations |
| } |
| return true; |
| } |
| |
| // |
| // Helpers. |
| // |
| |
| bool HLoopOptimization::TrySetPhiInduction(HPhi* phi, bool restrict_uses) { |
| // Start with empty phi induction. |
| iset_->clear(); |
| |
| // Special case Phis that have equivalent in a debuggable setup. Our graph checker isn't |
| // smart enough to follow strongly connected components (and it's probably not worth |
| // it to make it so). See b/33775412. |
| if (graph_->IsDebuggable() && phi->HasEquivalentPhi()) { |
| return false; |
| } |
| |
| // Lookup phi induction cycle. |
| ArenaSet<HInstruction*>* set = induction_range_.LookupCycle(phi); |
| if (set != nullptr) { |
| for (HInstruction* i : *set) { |
| // Check that, other than instructions that are no longer in the graph (removed earlier) |
| // each instruction is removable and, when restrict uses are requested, other than for phi, |
| // all uses are contained within the cycle. |
| if (!i->IsInBlock()) { |
| continue; |
| } else if (!i->IsRemovable()) { |
| return false; |
| } else if (i != phi && restrict_uses) { |
| // Deal with regular uses. |
| for (const HUseListNode<HInstruction*>& use : i->GetUses()) { |
| if (set->find(use.GetUser()) == set->end()) { |
| return false; |
| } |
| } |
| } |
| iset_->insert(i); // copy |
| } |
| return true; |
| } |
| return false; |
| } |
| |
| bool HLoopOptimization::TrySetPhiReduction(HPhi* phi) { |
| DCHECK(iset_->empty()); |
| // Only unclassified phi cycles are candidates for reductions. |
| if (induction_range_.IsClassified(phi)) { |
| return false; |
| } |
| // Accept operations like x = x + .., provided that the phi and the reduction are |
| // used exactly once inside the loop, and by each other. |
| HInputsRef inputs = phi->GetInputs(); |
| if (inputs.size() == 2) { |
| HInstruction* reduction = inputs[1]; |
| if (HasReductionFormat(reduction, phi)) { |
| HLoopInformation* loop_info = phi->GetBlock()->GetLoopInformation(); |
| uint32_t use_count = 0; |
| bool single_use_inside_loop = |
| // Reduction update only used by phi. |
| reduction->GetUses().HasExactlyOneElement() && |
| !reduction->HasEnvironmentUses() && |
| // Reduction update is only use of phi inside the loop. |
| IsOnlyUsedAfterLoop(loop_info, phi, /*collect_loop_uses*/ true, &use_count) && |
| iset_->size() == 1; |
| iset_->clear(); // leave the way you found it |
| if (single_use_inside_loop) { |
| // Link reduction back, and start recording feed value. |
| reductions_->Put(reduction, phi); |
| reductions_->Put(phi, phi->InputAt(0)); |
| return true; |
| } |
| } |
| } |
| return false; |
| } |
| |
| bool HLoopOptimization::TrySetSimpleLoopHeader(HBasicBlock* block, /*out*/ HPhi** main_phi) { |
| // Start with empty phi induction and reductions. |
| iset_->clear(); |
| reductions_->clear(); |
| |
| // Scan the phis to find the following (the induction structure has already |
| // been optimized, so we don't need to worry about trivial cases): |
| // (1) optional reductions in loop, |
| // (2) the main induction, used in loop control. |
| HPhi* phi = nullptr; |
| for (HInstructionIterator it(block->GetPhis()); !it.Done(); it.Advance()) { |
| if (TrySetPhiReduction(it.Current()->AsPhi())) { |
| continue; |
| } else if (phi == nullptr) { |
| // Found the first candidate for main induction. |
| phi = it.Current()->AsPhi(); |
| } else { |
| return false; |
| } |
| } |
| |
| // Then test for a typical loopheader: |
| // s: SuspendCheck |
| // c: Condition(phi, bound) |
| // i: If(c) |
| if (phi != nullptr && TrySetPhiInduction(phi, /*restrict_uses*/ false)) { |
| HInstruction* s = block->GetFirstInstruction(); |
| if (s != nullptr && s->IsSuspendCheck()) { |
| HInstruction* c = s->GetNext(); |
| if (c != nullptr && |
| c->IsCondition() && |
| c->GetUses().HasExactlyOneElement() && // only used for termination |
| !c->HasEnvironmentUses()) { // unlikely, but not impossible |
| HInstruction* i = c->GetNext(); |
| if (i != nullptr && i->IsIf() && i->InputAt(0) == c) { |
| iset_->insert(c); |
| iset_->insert(s); |
| *main_phi = phi; |
| return true; |
| } |
| } |
| } |
| } |
| return false; |
| } |
| |
| bool HLoopOptimization::IsEmptyBody(HBasicBlock* block) { |
| if (!block->GetPhis().IsEmpty()) { |
| return false; |
| } |
| for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) { |
| HInstruction* instruction = it.Current(); |
| if (!instruction->IsGoto() && iset_->find(instruction) == iset_->end()) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| bool HLoopOptimization::IsUsedOutsideLoop(HLoopInformation* loop_info, |
| HInstruction* instruction) { |
| // Deal with regular uses. |
| for (const HUseListNode<HInstruction*>& use : instruction->GetUses()) { |
| if (use.GetUser()->GetBlock()->GetLoopInformation() != loop_info) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| bool HLoopOptimization::IsOnlyUsedAfterLoop(HLoopInformation* loop_info, |
| HInstruction* instruction, |
| bool collect_loop_uses, |
| /*out*/ uint32_t* use_count) { |
| // Deal with regular uses. |
| for (const HUseListNode<HInstruction*>& use : instruction->GetUses()) { |
| HInstruction* user = use.GetUser(); |
| if (iset_->find(user) == iset_->end()) { // not excluded? |
| HLoopInformation* other_loop_info = user->GetBlock()->GetLoopInformation(); |
| if (other_loop_info != nullptr && other_loop_info->IsIn(*loop_info)) { |
| // If collect_loop_uses is set, simply keep adding those uses to the set. |
| // Otherwise, reject uses inside the loop that were not already in the set. |
| if (collect_loop_uses) { |
| iset_->insert(user); |
| continue; |
| } |
| return false; |
| } |
| ++*use_count; |
| } |
| } |
| return true; |
| } |
| |
| bool HLoopOptimization::TryReplaceWithLastValue(HLoopInformation* loop_info, |
| HInstruction* instruction, |
| HBasicBlock* block) { |
| // Try to replace outside uses with the last value. |
| if (induction_range_.CanGenerateLastValue(instruction)) { |
| HInstruction* replacement = induction_range_.GenerateLastValue(instruction, graph_, block); |
| // Deal with regular uses. |
| const HUseList<HInstruction*>& uses = instruction->GetUses(); |
| for (auto it = uses.begin(), end = uses.end(); it != end;) { |
| HInstruction* user = it->GetUser(); |
| size_t index = it->GetIndex(); |
| ++it; // increment before replacing |
| if (iset_->find(user) == iset_->end()) { // not excluded? |
| if (kIsDebugBuild) { |
| // We have checked earlier in 'IsOnlyUsedAfterLoop' that the use is after the loop. |
| HLoopInformation* other_loop_info = user->GetBlock()->GetLoopInformation(); |
| CHECK(other_loop_info == nullptr || !other_loop_info->IsIn(*loop_info)); |
| } |
| user->ReplaceInput(replacement, index); |
| induction_range_.Replace(user, instruction, replacement); // update induction |
| } |
| } |
| // Deal with environment uses. |
| const HUseList<HEnvironment*>& env_uses = instruction->GetEnvUses(); |
| for (auto it = env_uses.begin(), end = env_uses.end(); it != end;) { |
| HEnvironment* user = it->GetUser(); |
| size_t index = it->GetIndex(); |
| ++it; // increment before replacing |
| if (iset_->find(user->GetHolder()) == iset_->end()) { // not excluded? |
| // Only update environment uses after the loop. |
| HLoopInformation* other_loop_info = user->GetHolder()->GetBlock()->GetLoopInformation(); |
| if (other_loop_info == nullptr || !other_loop_info->IsIn(*loop_info)) { |
| user->RemoveAsUserOfInput(index); |
| user->SetRawEnvAt(index, replacement); |
| replacement->AddEnvUseAt(user, index); |
| } |
| } |
| } |
| return true; |
| } |
| return false; |
| } |
| |
| bool HLoopOptimization::TryAssignLastValue(HLoopInformation* loop_info, |
| HInstruction* instruction, |
| HBasicBlock* block, |
| bool collect_loop_uses) { |
| // Assigning the last value is always successful if there are no uses. |
| // Otherwise, it succeeds in a no early-exit loop by generating the |
| // proper last value assignment. |
| uint32_t use_count = 0; |
| return IsOnlyUsedAfterLoop(loop_info, instruction, collect_loop_uses, &use_count) && |
| (use_count == 0 || |
| (!IsEarlyExit(loop_info) && TryReplaceWithLastValue(loop_info, instruction, block))); |
| } |
| |
| void HLoopOptimization::RemoveDeadInstructions(const HInstructionList& list) { |
| for (HBackwardInstructionIterator i(list); !i.Done(); i.Advance()) { |
| HInstruction* instruction = i.Current(); |
| if (instruction->IsDeadAndRemovable()) { |
| simplified_ = true; |
| instruction->GetBlock()->RemoveInstructionOrPhi(instruction); |
| } |
| } |
| } |
| |
| bool HLoopOptimization::CanRemoveCycle() { |
| for (HInstruction* i : *iset_) { |
| // We can never remove instructions that have environment |
| // uses when we compile 'debuggable'. |
| if (i->HasEnvironmentUses() && graph_->IsDebuggable()) { |
| return false; |
| } |
| // A deoptimization should never have an environment input removed. |
| for (const HUseListNode<HEnvironment*>& use : i->GetEnvUses()) { |
| if (use.GetUser()->GetHolder()->IsDeoptimize()) { |
| return false; |
| } |
| } |
| } |
| return true; |
| } |
| |
| } // namespace art |