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1454 lines
59 KiB
1454 lines
59 KiB
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "induction_var_analysis.h"
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#include "induction_var_range.h"
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namespace art {
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/**
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* Since graph traversal may enter a SCC at any position, an initial representation may be rotated,
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* along dependences, viz. any of (a, b, c, d), (d, a, b, c) (c, d, a, b), (b, c, d, a) assuming
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* a chain of dependences (mutual independent items may occur in arbitrary order). For proper
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* classification, the lexicographically first loop-phi is rotated to the front.
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*/
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static void RotateEntryPhiFirst(HLoopInformation* loop,
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ArenaVector<HInstruction*>* scc,
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ArenaVector<HInstruction*>* new_scc) {
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// Find very first loop-phi.
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const HInstructionList& phis = loop->GetHeader()->GetPhis();
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HInstruction* phi = nullptr;
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size_t phi_pos = -1;
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const size_t size = scc->size();
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for (size_t i = 0; i < size; i++) {
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HInstruction* other = (*scc)[i];
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if (other->IsLoopHeaderPhi() && (phi == nullptr || phis.FoundBefore(other, phi))) {
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phi = other;
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phi_pos = i;
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}
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}
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// If found, bring that loop-phi to front.
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if (phi != nullptr) {
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new_scc->clear();
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for (size_t i = 0; i < size; i++) {
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new_scc->push_back((*scc)[phi_pos]);
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if (++phi_pos >= size) phi_pos = 0;
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}
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DCHECK_EQ(size, new_scc->size());
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scc->swap(*new_scc);
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}
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}
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/**
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* Returns true if the from/to types denote a narrowing, integral conversion (precision loss).
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*/
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static bool IsNarrowingIntegralConversion(DataType::Type from, DataType::Type to) {
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switch (from) {
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case DataType::Type::kInt64:
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return to == DataType::Type::kUint8 ||
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to == DataType::Type::kInt8 ||
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to == DataType::Type::kUint16 ||
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to == DataType::Type::kInt16 ||
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to == DataType::Type::kInt32;
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case DataType::Type::kInt32:
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return to == DataType::Type::kUint8 ||
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to == DataType::Type::kInt8 ||
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to == DataType::Type::kUint16 ||
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to == DataType::Type::kInt16;
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case DataType::Type::kUint16:
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case DataType::Type::kInt16:
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return to == DataType::Type::kUint8 || to == DataType::Type::kInt8;
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default:
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return false;
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}
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}
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/**
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* Returns result of implicit widening type conversion done in HIR.
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*/
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static DataType::Type ImplicitConversion(DataType::Type type) {
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switch (type) {
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case DataType::Type::kBool:
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case DataType::Type::kUint8:
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case DataType::Type::kInt8:
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case DataType::Type::kUint16:
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case DataType::Type::kInt16:
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return DataType::Type::kInt32;
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default:
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return type;
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}
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}
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/**
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* Returns true if loop is guarded by "a cmp b" on entry.
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*/
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static bool IsGuardedBy(HLoopInformation* loop,
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IfCondition cmp,
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HInstruction* a,
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HInstruction* b) {
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// Chase back through straightline code to the first potential
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// block that has a control dependence.
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// guard: if (x) bypass
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// |
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// entry: straightline code
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// |
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// preheader
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// |
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// header
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HBasicBlock* guard = loop->GetPreHeader();
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HBasicBlock* entry = loop->GetHeader();
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while (guard->GetPredecessors().size() == 1 &&
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guard->GetSuccessors().size() == 1) {
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entry = guard;
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guard = guard->GetSinglePredecessor();
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}
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// Find guard.
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HInstruction* control = guard->GetLastInstruction();
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if (!control->IsIf()) {
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return false;
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}
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HIf* ifs = control->AsIf();
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HInstruction* if_expr = ifs->InputAt(0);
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if (if_expr->IsCondition()) {
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IfCondition other_cmp = ifs->IfTrueSuccessor() == entry
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? if_expr->AsCondition()->GetCondition()
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: if_expr->AsCondition()->GetOppositeCondition();
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if (if_expr->InputAt(0) == a && if_expr->InputAt(1) == b) {
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return cmp == other_cmp;
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} else if (if_expr->InputAt(1) == a && if_expr->InputAt(0) == b) {
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switch (cmp) {
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case kCondLT: return other_cmp == kCondGT;
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case kCondLE: return other_cmp == kCondGE;
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case kCondGT: return other_cmp == kCondLT;
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case kCondGE: return other_cmp == kCondLE;
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default: LOG(FATAL) << "unexpected cmp: " << cmp;
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}
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}
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}
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return false;
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}
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/* Finds first loop header phi use. */
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HInstruction* FindFirstLoopHeaderPhiUse(HLoopInformation* loop, HInstruction* instruction) {
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for (const HUseListNode<HInstruction*>& use : instruction->GetUses()) {
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if (use.GetUser()->GetBlock() == loop->GetHeader() &&
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use.GetUser()->IsPhi() &&
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use.GetUser()->InputAt(1) == instruction) {
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return use.GetUser();
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}
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}
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return nullptr;
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}
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/**
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* Relinks the Phi structure after break-loop rewriting.
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*/
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bool FixOutsideUse(HLoopInformation* loop,
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HInstruction* instruction,
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HInstruction* replacement,
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bool rewrite) {
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// Deal with regular uses.
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const HUseList<HInstruction*>& uses = instruction->GetUses();
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for (auto it = uses.begin(), end = uses.end(); it != end; ) {
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HInstruction* user = it->GetUser();
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size_t index = it->GetIndex();
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++it; // increment prior to potential removal
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if (user->GetBlock()->GetLoopInformation() != loop) {
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if (replacement == nullptr) {
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return false;
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} else if (rewrite) {
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user->ReplaceInput(replacement, index);
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}
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}
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}
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// Deal with environment uses.
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const HUseList<HEnvironment*>& env_uses = instruction->GetEnvUses();
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for (auto it = env_uses.begin(), end = env_uses.end(); it != end;) {
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HEnvironment* user = it->GetUser();
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size_t index = it->GetIndex();
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++it; // increment prior to potential removal
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if (user->GetHolder()->GetBlock()->GetLoopInformation() != loop) {
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if (replacement == nullptr) {
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return false;
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} else if (rewrite) {
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user->RemoveAsUserOfInput(index);
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user->SetRawEnvAt(index, replacement);
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replacement->AddEnvUseAt(user, index);
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}
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}
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}
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return true;
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}
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/**
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* Test and rewrite the loop body of a break-loop. Returns true on success.
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*/
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bool RewriteBreakLoopBody(HLoopInformation* loop,
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HBasicBlock* body,
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HInstruction* cond,
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HInstruction* index,
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HInstruction* upper,
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bool rewrite) {
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// Deal with Phis. Outside use prohibited, except for index (which gets exit value).
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for (HInstructionIterator it(loop->GetHeader()->GetPhis()); !it.Done(); it.Advance()) {
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HInstruction* exit_value = it.Current() == index ? upper : nullptr;
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if (!FixOutsideUse(loop, it.Current(), exit_value, rewrite)) {
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return false;
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}
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}
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// Deal with other statements in header.
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for (HInstruction* m = cond->GetPrevious(), *p = nullptr; m && !m->IsSuspendCheck(); m = p) {
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p = m->GetPrevious();
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if (rewrite) {
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m->MoveBefore(body->GetFirstInstruction(), false);
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}
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if (!FixOutsideUse(loop, m, FindFirstLoopHeaderPhiUse(loop, m), rewrite)) {
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return false;
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}
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}
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return true;
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}
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//
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// Class methods.
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//
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HInductionVarAnalysis::HInductionVarAnalysis(HGraph* graph, const char* name)
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: HOptimization(graph, name),
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global_depth_(0),
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stack_(graph->GetAllocator()->Adapter(kArenaAllocInductionVarAnalysis)),
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map_(std::less<HInstruction*>(),
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graph->GetAllocator()->Adapter(kArenaAllocInductionVarAnalysis)),
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scc_(graph->GetAllocator()->Adapter(kArenaAllocInductionVarAnalysis)),
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cycle_(std::less<HInstruction*>(),
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graph->GetAllocator()->Adapter(kArenaAllocInductionVarAnalysis)),
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type_(DataType::Type::kVoid),
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induction_(std::less<HLoopInformation*>(),
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graph->GetAllocator()->Adapter(kArenaAllocInductionVarAnalysis)),
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cycles_(std::less<HPhi*>(),
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graph->GetAllocator()->Adapter(kArenaAllocInductionVarAnalysis)) {
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}
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bool HInductionVarAnalysis::Run() {
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// Detects sequence variables (generalized induction variables) during an outer to inner
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// traversal of all loops using Gerlek's algorithm. The order is important to enable
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// range analysis on outer loop while visiting inner loops.
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for (HBasicBlock* graph_block : graph_->GetReversePostOrder()) {
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// Don't analyze irreducible loops.
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if (graph_block->IsLoopHeader() && !graph_block->GetLoopInformation()->IsIrreducible()) {
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VisitLoop(graph_block->GetLoopInformation());
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}
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}
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return !induction_.empty();
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}
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void HInductionVarAnalysis::VisitLoop(HLoopInformation* loop) {
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// Find strongly connected components (SSCs) in the SSA graph of this loop using Tarjan's
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// algorithm. Due to the descendant-first nature, classification happens "on-demand".
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global_depth_ = 0;
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DCHECK(stack_.empty());
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map_.clear();
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for (HBlocksInLoopIterator it_loop(*loop); !it_loop.Done(); it_loop.Advance()) {
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HBasicBlock* loop_block = it_loop.Current();
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DCHECK(loop_block->IsInLoop());
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if (loop_block->GetLoopInformation() != loop) {
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continue; // Inner loops visited later.
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}
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// Visit phi-operations and instructions.
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for (HInstructionIterator it(loop_block->GetPhis()); !it.Done(); it.Advance()) {
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HInstruction* instruction = it.Current();
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if (!IsVisitedNode(instruction)) {
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VisitNode(loop, instruction);
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}
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}
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for (HInstructionIterator it(loop_block->GetInstructions()); !it.Done(); it.Advance()) {
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HInstruction* instruction = it.Current();
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if (!IsVisitedNode(instruction)) {
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VisitNode(loop, instruction);
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}
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}
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}
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DCHECK(stack_.empty());
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map_.clear();
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// Determine the loop's trip-count.
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VisitControl(loop);
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}
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void HInductionVarAnalysis::VisitNode(HLoopInformation* loop, HInstruction* instruction) {
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const uint32_t d1 = ++global_depth_;
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map_.Put(instruction, NodeInfo(d1));
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stack_.push_back(instruction);
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// Visit all descendants.
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uint32_t low = d1;
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for (HInstruction* input : instruction->GetInputs()) {
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low = std::min(low, VisitDescendant(loop, input));
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}
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// Lower or found SCC?
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if (low < d1) {
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map_.find(instruction)->second.depth = low;
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} else {
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scc_.clear();
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cycle_.clear();
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// Pop the stack to build the SCC for classification.
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while (!stack_.empty()) {
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HInstruction* x = stack_.back();
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scc_.push_back(x);
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stack_.pop_back();
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map_.find(x)->second.done = true;
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if (x == instruction) {
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break;
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}
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}
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// Type of induction.
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type_ = scc_[0]->GetType();
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// Classify the SCC.
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if (scc_.size() == 1 && !scc_[0]->IsLoopHeaderPhi()) {
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ClassifyTrivial(loop, scc_[0]);
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} else {
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ClassifyNonTrivial(loop);
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}
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scc_.clear();
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cycle_.clear();
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}
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}
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uint32_t HInductionVarAnalysis::VisitDescendant(HLoopInformation* loop, HInstruction* instruction) {
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// If the definition is either outside the loop (loop invariant entry value)
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// or assigned in inner loop (inner exit value), the traversal stops.
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HLoopInformation* otherLoop = instruction->GetBlock()->GetLoopInformation();
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if (otherLoop != loop) {
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return global_depth_;
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}
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// Inspect descendant node.
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if (!IsVisitedNode(instruction)) {
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VisitNode(loop, instruction);
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return map_.find(instruction)->second.depth;
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} else {
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auto it = map_.find(instruction);
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return it->second.done ? global_depth_ : it->second.depth;
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}
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}
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void HInductionVarAnalysis::ClassifyTrivial(HLoopInformation* loop, HInstruction* instruction) {
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InductionInfo* info = nullptr;
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if (instruction->IsPhi()) {
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info = TransferPhi(loop, instruction, /*input_index*/ 0, /*adjust_input_size*/ 0);
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} else if (instruction->IsAdd()) {
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info = TransferAddSub(LookupInfo(loop, instruction->InputAt(0)),
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LookupInfo(loop, instruction->InputAt(1)), kAdd);
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} else if (instruction->IsSub()) {
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info = TransferAddSub(LookupInfo(loop, instruction->InputAt(0)),
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LookupInfo(loop, instruction->InputAt(1)), kSub);
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} else if (instruction->IsNeg()) {
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info = TransferNeg(LookupInfo(loop, instruction->InputAt(0)));
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} else if (instruction->IsMul()) {
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info = TransferMul(LookupInfo(loop, instruction->InputAt(0)),
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LookupInfo(loop, instruction->InputAt(1)));
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} else if (instruction->IsShl()) {
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HInstruction* mulc = GetShiftConstant(loop, instruction, /*initial*/ nullptr);
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if (mulc != nullptr) {
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info = TransferMul(LookupInfo(loop, instruction->InputAt(0)),
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LookupInfo(loop, mulc));
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}
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} else if (instruction->IsSelect()) {
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info = TransferPhi(loop, instruction, /*input_index*/ 0, /*adjust_input_size*/ 1);
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} else if (instruction->IsTypeConversion()) {
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info = TransferConversion(LookupInfo(loop, instruction->InputAt(0)),
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instruction->AsTypeConversion()->GetInputType(),
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instruction->AsTypeConversion()->GetResultType());
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} else if (instruction->IsBoundsCheck()) {
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info = LookupInfo(loop, instruction->InputAt(0)); // Pass-through.
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}
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// Successfully classified?
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if (info != nullptr) {
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AssignInfo(loop, instruction, info);
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}
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}
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void HInductionVarAnalysis::ClassifyNonTrivial(HLoopInformation* loop) {
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const size_t size = scc_.size();
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DCHECK_GE(size, 1u);
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// Rotate proper loop-phi to front.
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if (size > 1) {
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ArenaVector<HInstruction*> other(
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graph_->GetAllocator()->Adapter(kArenaAllocInductionVarAnalysis));
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RotateEntryPhiFirst(loop, &scc_, &other);
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}
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// Analyze from loop-phi onwards.
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HInstruction* phi = scc_[0];
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if (!phi->IsLoopHeaderPhi()) {
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return;
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}
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// External link should be loop invariant.
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InductionInfo* initial = LookupInfo(loop, phi->InputAt(0));
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if (initial == nullptr || initial->induction_class != kInvariant) {
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return;
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}
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// Store interesting cycle in each loop phi.
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for (size_t i = 0; i < size; i++) {
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if (scc_[i]->IsLoopHeaderPhi()) {
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AssignCycle(scc_[i]->AsPhi());
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}
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}
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// Singleton is wrap-around induction if all internal links have the same meaning.
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if (size == 1) {
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InductionInfo* update = TransferPhi(loop, phi, /*input_index*/ 1, /*adjust_input_size*/ 0);
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if (update != nullptr) {
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AssignInfo(loop, phi, CreateInduction(kWrapAround,
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kNop,
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initial,
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update,
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/*fetch*/ nullptr,
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type_));
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}
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return;
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}
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// Inspect remainder of the cycle that resides in scc_. The cycle_ mapping assigns
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// temporary meaning to its nodes, seeded from the phi instruction and back.
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for (size_t i = 1; i < size; i++) {
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HInstruction* instruction = scc_[i];
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InductionInfo* update = nullptr;
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if (instruction->IsPhi()) {
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update = SolvePhiAllInputs(loop, phi, instruction);
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} else if (instruction->IsAdd()) {
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update = SolveAddSub(
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loop, phi, instruction, instruction->InputAt(0), instruction->InputAt(1), kAdd, true);
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} else if (instruction->IsSub()) {
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update = SolveAddSub(
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loop, phi, instruction, instruction->InputAt(0), instruction->InputAt(1), kSub, true);
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} else if (instruction->IsMul()) {
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update = SolveOp(
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loop, phi, instruction, instruction->InputAt(0), instruction->InputAt(1), kMul);
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} else if (instruction->IsDiv()) {
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update = SolveOp(
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loop, phi, instruction, instruction->InputAt(0), instruction->InputAt(1), kDiv);
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} else if (instruction->IsRem()) {
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update = SolveOp(
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loop, phi, instruction, instruction->InputAt(0), instruction->InputAt(1), kRem);
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} else if (instruction->IsShl()) {
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HInstruction* mulc = GetShiftConstant(loop, instruction, /*initial*/ nullptr);
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if (mulc != nullptr) {
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update = SolveOp(loop, phi, instruction, instruction->InputAt(0), mulc, kMul);
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}
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} else if (instruction->IsShr() || instruction->IsUShr()) {
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HInstruction* divc = GetShiftConstant(loop, instruction, initial);
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if (divc != nullptr) {
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update = SolveOp(loop, phi, instruction, instruction->InputAt(0), divc, kDiv);
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}
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} else if (instruction->IsXor()) {
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update = SolveOp(
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loop, phi, instruction, instruction->InputAt(0), instruction->InputAt(1), kXor);
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} else if (instruction->IsEqual()) {
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update = SolveTest(loop, phi, instruction, 0);
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} else if (instruction->IsNotEqual()) {
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update = SolveTest(loop, phi, instruction, 1);
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} else if (instruction->IsSelect()) {
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update = SolvePhi(instruction, /*input_index*/ 0, /*adjust_input_size*/ 1); // acts like Phi
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} else if (instruction->IsTypeConversion()) {
|
|
update = SolveConversion(loop, phi, instruction->AsTypeConversion());
|
|
}
|
|
if (update == nullptr) {
|
|
return;
|
|
}
|
|
cycle_.Put(instruction, update);
|
|
}
|
|
|
|
// Success if all internal links received the same temporary meaning.
|
|
InductionInfo* induction = SolvePhi(phi, /*input_index*/ 1, /*adjust_input_size*/ 0);
|
|
if (induction != nullptr) {
|
|
switch (induction->induction_class) {
|
|
case kInvariant:
|
|
// Construct combined stride of the linear induction.
|
|
induction = CreateInduction(kLinear, kNop, induction, initial, /*fetch*/ nullptr, type_);
|
|
FALLTHROUGH_INTENDED;
|
|
case kPolynomial:
|
|
case kGeometric:
|
|
case kWrapAround:
|
|
// Classify first phi and then the rest of the cycle "on-demand".
|
|
// Statements are scanned in order.
|
|
AssignInfo(loop, phi, induction);
|
|
for (size_t i = 1; i < size; i++) {
|
|
ClassifyTrivial(loop, scc_[i]);
|
|
}
|
|
break;
|
|
case kPeriodic:
|
|
// Classify all elements in the cycle with the found periodic induction while
|
|
// rotating each first element to the end. Lastly, phi is classified.
|
|
// Statements are scanned in reverse order.
|
|
for (size_t i = size - 1; i >= 1; i--) {
|
|
AssignInfo(loop, scc_[i], induction);
|
|
induction = RotatePeriodicInduction(induction->op_b, induction->op_a);
|
|
}
|
|
AssignInfo(loop, phi, induction);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::RotatePeriodicInduction(
|
|
InductionInfo* induction,
|
|
InductionInfo* last) {
|
|
// Rotates a periodic induction of the form
|
|
// (a, b, c, d, e)
|
|
// into
|
|
// (b, c, d, e, a)
|
|
// in preparation of assigning this to the previous variable in the sequence.
|
|
if (induction->induction_class == kInvariant) {
|
|
return CreateInduction(kPeriodic,
|
|
kNop,
|
|
induction,
|
|
last,
|
|
/*fetch*/ nullptr,
|
|
type_);
|
|
}
|
|
return CreateInduction(kPeriodic,
|
|
kNop,
|
|
induction->op_a,
|
|
RotatePeriodicInduction(induction->op_b, last),
|
|
/*fetch*/ nullptr,
|
|
type_);
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::TransferPhi(HLoopInformation* loop,
|
|
HInstruction* phi,
|
|
size_t input_index,
|
|
size_t adjust_input_size) {
|
|
// Match all phi inputs from input_index onwards exactly.
|
|
HInputsRef inputs = phi->GetInputs();
|
|
DCHECK_LT(input_index, inputs.size());
|
|
InductionInfo* a = LookupInfo(loop, inputs[input_index]);
|
|
for (size_t i = input_index + 1, n = inputs.size() - adjust_input_size; i < n; i++) {
|
|
InductionInfo* b = LookupInfo(loop, inputs[i]);
|
|
if (!InductionEqual(a, b)) {
|
|
return nullptr;
|
|
}
|
|
}
|
|
return a;
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::TransferAddSub(InductionInfo* a,
|
|
InductionInfo* b,
|
|
InductionOp op) {
|
|
// Transfer over an addition or subtraction: any invariant, linear, polynomial, geometric,
|
|
// wrap-around, or periodic can be combined with an invariant to yield a similar result.
|
|
// Two linear or two polynomial inputs can be combined too. Other combinations fail.
|
|
if (a != nullptr && b != nullptr) {
|
|
if (IsNarrowingLinear(a) || IsNarrowingLinear(b)) {
|
|
return nullptr; // no transfer
|
|
} else if (a->induction_class == kInvariant && b->induction_class == kInvariant) {
|
|
return CreateInvariantOp(op, a, b); // direct invariant
|
|
} else if ((a->induction_class == kLinear && b->induction_class == kLinear) ||
|
|
(a->induction_class == kPolynomial && b->induction_class == kPolynomial)) {
|
|
// Rule induc(a, b) + induc(a', b') -> induc(a + a', b + b').
|
|
InductionInfo* new_a = TransferAddSub(a->op_a, b->op_a, op);
|
|
InductionInfo* new_b = TransferAddSub(a->op_b, b->op_b, op);
|
|
if (new_a != nullptr && new_b != nullptr) {
|
|
return CreateInduction(a->induction_class, a->operation, new_a, new_b, a->fetch, type_);
|
|
}
|
|
} else if (a->induction_class == kInvariant) {
|
|
// Rule a + induc(a', b') -> induc(a', a + b') or induc(a + a', a + b').
|
|
InductionInfo* new_a = b->op_a;
|
|
InductionInfo* new_b = TransferAddSub(a, b->op_b, op);
|
|
if (b->induction_class == kWrapAround || b->induction_class == kPeriodic) {
|
|
new_a = TransferAddSub(a, new_a, op);
|
|
} else if (op == kSub) { // Negation required.
|
|
new_a = TransferNeg(new_a);
|
|
}
|
|
if (new_a != nullptr && new_b != nullptr) {
|
|
return CreateInduction(b->induction_class, b->operation, new_a, new_b, b->fetch, type_);
|
|
}
|
|
} else if (b->induction_class == kInvariant) {
|
|
// Rule induc(a, b) + b' -> induc(a, b + b') or induc(a + b', b + b').
|
|
InductionInfo* new_a = a->op_a;
|
|
InductionInfo* new_b = TransferAddSub(a->op_b, b, op);
|
|
if (a->induction_class == kWrapAround || a->induction_class == kPeriodic) {
|
|
new_a = TransferAddSub(new_a, b, op);
|
|
}
|
|
if (new_a != nullptr && new_b != nullptr) {
|
|
return CreateInduction(a->induction_class, a->operation, new_a, new_b, a->fetch, type_);
|
|
}
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::TransferNeg(InductionInfo* a) {
|
|
// Transfer over a unary negation: an invariant, linear, polynomial, geometric (mul),
|
|
// wrap-around, or periodic input yields a similar but negated induction as result.
|
|
if (a != nullptr) {
|
|
if (IsNarrowingLinear(a)) {
|
|
return nullptr; // no transfer
|
|
} else if (a->induction_class == kInvariant) {
|
|
return CreateInvariantOp(kNeg, nullptr, a); // direct invariant
|
|
} else if (a->induction_class != kGeometric || a->operation == kMul) {
|
|
// Rule - induc(a, b) -> induc(-a, -b).
|
|
InductionInfo* new_a = TransferNeg(a->op_a);
|
|
InductionInfo* new_b = TransferNeg(a->op_b);
|
|
if (new_a != nullptr && new_b != nullptr) {
|
|
return CreateInduction(a->induction_class, a->operation, new_a, new_b, a->fetch, type_);
|
|
}
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::TransferMul(InductionInfo* a,
|
|
InductionInfo* b) {
|
|
// Transfer over a multiplication: any invariant, linear, polynomial, geometric (mul),
|
|
// wrap-around, or periodic can be multiplied with an invariant to yield a similar
|
|
// but multiplied result. Two non-invariant inputs cannot be multiplied, however.
|
|
if (a != nullptr && b != nullptr) {
|
|
if (IsNarrowingLinear(a) || IsNarrowingLinear(b)) {
|
|
return nullptr; // no transfer
|
|
} else if (a->induction_class == kInvariant && b->induction_class == kInvariant) {
|
|
return CreateInvariantOp(kMul, a, b); // direct invariant
|
|
} else if (a->induction_class == kInvariant && (b->induction_class != kGeometric ||
|
|
b->operation == kMul)) {
|
|
// Rule a * induc(a', b') -> induc(a * a', b * b').
|
|
InductionInfo* new_a = TransferMul(a, b->op_a);
|
|
InductionInfo* new_b = TransferMul(a, b->op_b);
|
|
if (new_a != nullptr && new_b != nullptr) {
|
|
return CreateInduction(b->induction_class, b->operation, new_a, new_b, b->fetch, type_);
|
|
}
|
|
} else if (b->induction_class == kInvariant && (a->induction_class != kGeometric ||
|
|
a->operation == kMul)) {
|
|
// Rule induc(a, b) * b' -> induc(a * b', b * b').
|
|
InductionInfo* new_a = TransferMul(a->op_a, b);
|
|
InductionInfo* new_b = TransferMul(a->op_b, b);
|
|
if (new_a != nullptr && new_b != nullptr) {
|
|
return CreateInduction(a->induction_class, a->operation, new_a, new_b, a->fetch, type_);
|
|
}
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::TransferConversion(
|
|
InductionInfo* a,
|
|
DataType::Type from,
|
|
DataType::Type to) {
|
|
if (a != nullptr) {
|
|
// Allow narrowing conversion on linear induction in certain cases:
|
|
// induction is already at narrow type, or can be made narrower.
|
|
if (IsNarrowingIntegralConversion(from, to) &&
|
|
a->induction_class == kLinear &&
|
|
(a->type == to || IsNarrowingIntegralConversion(a->type, to))) {
|
|
return CreateInduction(kLinear, kNop, a->op_a, a->op_b, a->fetch, to);
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::SolvePhi(HInstruction* phi,
|
|
size_t input_index,
|
|
size_t adjust_input_size) {
|
|
// Match all phi inputs from input_index onwards exactly.
|
|
HInputsRef inputs = phi->GetInputs();
|
|
DCHECK_LT(input_index, inputs.size());
|
|
auto ita = cycle_.find(inputs[input_index]);
|
|
if (ita != cycle_.end()) {
|
|
for (size_t i = input_index + 1, n = inputs.size() - adjust_input_size; i < n; i++) {
|
|
auto itb = cycle_.find(inputs[i]);
|
|
if (itb == cycle_.end() ||
|
|
!HInductionVarAnalysis::InductionEqual(ita->second, itb->second)) {
|
|
return nullptr;
|
|
}
|
|
}
|
|
return ita->second;
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::SolvePhiAllInputs(
|
|
HLoopInformation* loop,
|
|
HInstruction* entry_phi,
|
|
HInstruction* phi) {
|
|
// Match all phi inputs.
|
|
InductionInfo* match = SolvePhi(phi, /*input_index*/ 0, /*adjust_input_size*/ 0);
|
|
if (match != nullptr) {
|
|
return match;
|
|
}
|
|
|
|
// Otherwise, try to solve for a periodic seeded from phi onward.
|
|
// Only tight multi-statement cycles are considered in order to
|
|
// simplify rotating the periodic during the final classification.
|
|
if (phi->IsLoopHeaderPhi() && phi->InputCount() == 2) {
|
|
InductionInfo* a = LookupInfo(loop, phi->InputAt(0));
|
|
if (a != nullptr && a->induction_class == kInvariant) {
|
|
if (phi->InputAt(1) == entry_phi) {
|
|
InductionInfo* initial = LookupInfo(loop, entry_phi->InputAt(0));
|
|
return CreateInduction(kPeriodic, kNop, a, initial, /*fetch*/ nullptr, type_);
|
|
}
|
|
InductionInfo* b = SolvePhi(phi, /*input_index*/ 1, /*adjust_input_size*/ 0);
|
|
if (b != nullptr && b->induction_class == kPeriodic) {
|
|
return CreateInduction(kPeriodic, kNop, a, b, /*fetch*/ nullptr, type_);
|
|
}
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::SolveAddSub(HLoopInformation* loop,
|
|
HInstruction* entry_phi,
|
|
HInstruction* instruction,
|
|
HInstruction* x,
|
|
HInstruction* y,
|
|
InductionOp op,
|
|
bool is_first_call) {
|
|
// Solve within a cycle over an addition or subtraction.
|
|
InductionInfo* b = LookupInfo(loop, y);
|
|
if (b != nullptr) {
|
|
if (b->induction_class == kInvariant) {
|
|
// Adding or subtracting an invariant value, seeded from phi,
|
|
// keeps adding to the stride of the linear induction.
|
|
if (x == entry_phi) {
|
|
return (op == kAdd) ? b : CreateInvariantOp(kNeg, nullptr, b);
|
|
}
|
|
auto it = cycle_.find(x);
|
|
if (it != cycle_.end()) {
|
|
InductionInfo* a = it->second;
|
|
if (a->induction_class == kInvariant) {
|
|
return CreateInvariantOp(op, a, b);
|
|
}
|
|
}
|
|
} else if (b->induction_class == kLinear && b->type == type_) {
|
|
// Solve within a tight cycle that adds a term that is already classified as a linear
|
|
// induction for a polynomial induction k = k + i (represented as sum over linear terms).
|
|
if (x == entry_phi && entry_phi->InputCount() == 2 && instruction == entry_phi->InputAt(1)) {
|
|
InductionInfo* initial = LookupInfo(loop, entry_phi->InputAt(0));
|
|
InductionInfo* new_a = op == kAdd ? b : TransferNeg(b);
|
|
if (new_a != nullptr) {
|
|
return CreateInduction(kPolynomial, kNop, new_a, initial, /*fetch*/ nullptr, type_);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Try some alternatives before failing.
|
|
if (op == kAdd) {
|
|
// Try the other way around for an addition if considered for first time.
|
|
if (is_first_call) {
|
|
return SolveAddSub(loop, entry_phi, instruction, y, x, op, false);
|
|
}
|
|
} else if (op == kSub) {
|
|
// Solve within a tight cycle that is formed by exactly two instructions,
|
|
// one phi and one update, for a periodic idiom of the form k = c - k.
|
|
if (y == entry_phi && entry_phi->InputCount() == 2 && instruction == entry_phi->InputAt(1)) {
|
|
InductionInfo* a = LookupInfo(loop, x);
|
|
if (a != nullptr && a->induction_class == kInvariant) {
|
|
InductionInfo* initial = LookupInfo(loop, entry_phi->InputAt(0));
|
|
return CreateInduction(kPeriodic,
|
|
kNop,
|
|
CreateInvariantOp(kSub, a, initial),
|
|
initial,
|
|
/*fetch*/ nullptr,
|
|
type_);
|
|
}
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::SolveOp(HLoopInformation* loop,
|
|
HInstruction* entry_phi,
|
|
HInstruction* instruction,
|
|
HInstruction* x,
|
|
HInstruction* y,
|
|
InductionOp op) {
|
|
// Solve within a tight cycle for a binary operation k = k op c or, for some op, k = c op k.
|
|
if (entry_phi->InputCount() == 2 && instruction == entry_phi->InputAt(1)) {
|
|
InductionInfo* c = nullptr;
|
|
InductionInfo* b = LookupInfo(loop, y);
|
|
if (b != nullptr && b->induction_class == kInvariant && entry_phi == x) {
|
|
c = b;
|
|
} else if (op != kDiv && op != kRem) {
|
|
InductionInfo* a = LookupInfo(loop, x);
|
|
if (a != nullptr && a->induction_class == kInvariant && entry_phi == y) {
|
|
c = a;
|
|
}
|
|
}
|
|
// Found suitable operand left or right?
|
|
if (c != nullptr) {
|
|
InductionInfo* initial = LookupInfo(loop, entry_phi->InputAt(0));
|
|
switch (op) {
|
|
case kMul:
|
|
case kDiv:
|
|
// Restrict base of geometric induction to direct fetch.
|
|
if (c->operation == kFetch) {
|
|
return CreateInduction(kGeometric,
|
|
op,
|
|
initial,
|
|
CreateConstant(0, type_),
|
|
c->fetch,
|
|
type_);
|
|
}
|
|
break;
|
|
case kRem:
|
|
// Idiomatic MOD wrap-around induction.
|
|
return CreateInduction(kWrapAround,
|
|
kNop,
|
|
initial,
|
|
CreateInvariantOp(kRem, initial, c),
|
|
/*fetch*/ nullptr,
|
|
type_);
|
|
case kXor:
|
|
// Idiomatic XOR periodic induction.
|
|
return CreateInduction(kPeriodic,
|
|
kNop,
|
|
CreateInvariantOp(kXor, initial, c),
|
|
initial,
|
|
/*fetch*/ nullptr,
|
|
type_);
|
|
default:
|
|
LOG(FATAL) << op;
|
|
UNREACHABLE();
|
|
}
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::SolveTest(HLoopInformation* loop,
|
|
HInstruction* entry_phi,
|
|
HInstruction* instruction,
|
|
int64_t opposite_value) {
|
|
// Detect hidden XOR construction in x = (x == false) or x = (x != true).
|
|
int64_t value = -1;
|
|
HInstruction* x = instruction->InputAt(0);
|
|
HInstruction* y = instruction->InputAt(1);
|
|
if (IsExact(LookupInfo(loop, x), &value) && value == opposite_value) {
|
|
return SolveOp(loop, entry_phi, instruction, graph_->GetIntConstant(1), y, kXor);
|
|
} else if (IsExact(LookupInfo(loop, y), &value) && value == opposite_value) {
|
|
return SolveOp(loop, entry_phi, instruction, x, graph_->GetIntConstant(1), kXor);
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::SolveConversion(
|
|
HLoopInformation* loop,
|
|
HInstruction* entry_phi,
|
|
HTypeConversion* conversion) {
|
|
DataType::Type from = conversion->GetInputType();
|
|
DataType::Type to = conversion->GetResultType();
|
|
// A narrowing conversion is allowed as *last* operation of the cycle of a linear induction
|
|
// with an initial value that fits the type, provided that the narrowest encountered type is
|
|
// recorded with the induction to account for the precision loss. The narrower induction does
|
|
// *not* transfer to any wider operations, however, since these may yield out-of-type values
|
|
if (entry_phi->InputCount() == 2 && conversion == entry_phi->InputAt(1)) {
|
|
int64_t min = DataType::MinValueOfIntegralType(to);
|
|
int64_t max = DataType::MaxValueOfIntegralType(to);
|
|
int64_t value = 0;
|
|
InductionInfo* initial = LookupInfo(loop, entry_phi->InputAt(0));
|
|
if (IsNarrowingIntegralConversion(from, to) &&
|
|
IsAtLeast(initial, &value) && value >= min &&
|
|
IsAtMost(initial, &value) && value <= max) {
|
|
auto it = cycle_.find(conversion->GetInput());
|
|
if (it != cycle_.end() && it->second->induction_class == kInvariant) {
|
|
type_ = to;
|
|
return it->second;
|
|
}
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
//
|
|
// Loop trip count analysis methods.
|
|
//
|
|
|
|
void HInductionVarAnalysis::VisitControl(HLoopInformation* loop) {
|
|
HInstruction* control = loop->GetHeader()->GetLastInstruction();
|
|
if (control->IsIf()) {
|
|
HIf* ifs = control->AsIf();
|
|
HBasicBlock* if_true = ifs->IfTrueSuccessor();
|
|
HBasicBlock* if_false = ifs->IfFalseSuccessor();
|
|
HInstruction* if_expr = ifs->InputAt(0);
|
|
// Determine if loop has following structure in header.
|
|
// loop-header: ....
|
|
// if (condition) goto X
|
|
if (if_expr->IsCondition()) {
|
|
HCondition* condition = if_expr->AsCondition();
|
|
InductionInfo* a = LookupInfo(loop, condition->InputAt(0));
|
|
InductionInfo* b = LookupInfo(loop, condition->InputAt(1));
|
|
DataType::Type type = ImplicitConversion(condition->InputAt(0)->GetType());
|
|
// Determine if the loop control uses a known sequence on an if-exit (X outside) or on
|
|
// an if-iterate (X inside), expressed as if-iterate when passed into VisitCondition().
|
|
if (a == nullptr || b == nullptr) {
|
|
return; // Loop control is not a sequence.
|
|
} else if (if_true->GetLoopInformation() != loop && if_false->GetLoopInformation() == loop) {
|
|
VisitCondition(loop, if_false, a, b, type, condition->GetOppositeCondition());
|
|
} else if (if_true->GetLoopInformation() == loop && if_false->GetLoopInformation() != loop) {
|
|
VisitCondition(loop, if_true, a, b, type, condition->GetCondition());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void HInductionVarAnalysis::VisitCondition(HLoopInformation* loop,
|
|
HBasicBlock* body,
|
|
InductionInfo* a,
|
|
InductionInfo* b,
|
|
DataType::Type type,
|
|
IfCondition cmp) {
|
|
if (a->induction_class == kInvariant && b->induction_class == kLinear) {
|
|
// Swap condition if induction is at right-hand-side (e.g. U > i is same as i < U).
|
|
switch (cmp) {
|
|
case kCondLT: VisitCondition(loop, body, b, a, type, kCondGT); break;
|
|
case kCondLE: VisitCondition(loop, body, b, a, type, kCondGE); break;
|
|
case kCondGT: VisitCondition(loop, body, b, a, type, kCondLT); break;
|
|
case kCondGE: VisitCondition(loop, body, b, a, type, kCondLE); break;
|
|
case kCondNE: VisitCondition(loop, body, b, a, type, kCondNE); break;
|
|
default: break;
|
|
}
|
|
} else if (a->induction_class == kLinear && b->induction_class == kInvariant) {
|
|
// Analyze condition with induction at left-hand-side (e.g. i < U).
|
|
InductionInfo* lower_expr = a->op_b;
|
|
InductionInfo* upper_expr = b;
|
|
InductionInfo* stride_expr = a->op_a;
|
|
// Test for constant stride and integral condition.
|
|
int64_t stride_value = 0;
|
|
if (!IsExact(stride_expr, &stride_value)) {
|
|
return; // unknown stride
|
|
} else if (type != DataType::Type::kInt32 && type != DataType::Type::kInt64) {
|
|
return; // not integral
|
|
}
|
|
// Since loops with a i != U condition will not be normalized by the method below, first
|
|
// try to rewrite a break-loop with terminating condition i != U into an equivalent loop
|
|
// with non-strict end condition i <= U or i >= U if such a rewriting is possible and safe.
|
|
if (cmp == kCondNE && RewriteBreakLoop(loop, body, stride_value, type)) {
|
|
cmp = stride_value > 0 ? kCondLE : kCondGE;
|
|
}
|
|
// If this rewriting failed, try to rewrite condition i != U into strict end condition i < U
|
|
// or i > U if this end condition is reached exactly (tested by verifying if the loop has a
|
|
// unit stride and the non-strict condition would be always taken).
|
|
if (cmp == kCondNE && ((stride_value == +1 && IsTaken(lower_expr, upper_expr, kCondLE)) ||
|
|
(stride_value == -1 && IsTaken(lower_expr, upper_expr, kCondGE)))) {
|
|
cmp = stride_value > 0 ? kCondLT : kCondGT;
|
|
}
|
|
// A mismatch between the type of condition and the induction is only allowed if the,
|
|
// necessarily narrower, induction range fits the narrower control.
|
|
if (type != a->type &&
|
|
!FitsNarrowerControl(lower_expr, upper_expr, stride_value, a->type, cmp)) {
|
|
return; // mismatched type
|
|
}
|
|
// Normalize a linear loop control with a nonzero stride:
|
|
// stride > 0, either i < U or i <= U
|
|
// stride < 0, either i > U or i >= U
|
|
if ((stride_value > 0 && (cmp == kCondLT || cmp == kCondLE)) ||
|
|
(stride_value < 0 && (cmp == kCondGT || cmp == kCondGE))) {
|
|
VisitTripCount(loop, lower_expr, upper_expr, stride_expr, stride_value, type, cmp);
|
|
}
|
|
}
|
|
}
|
|
|
|
void HInductionVarAnalysis::VisitTripCount(HLoopInformation* loop,
|
|
InductionInfo* lower_expr,
|
|
InductionInfo* upper_expr,
|
|
InductionInfo* stride_expr,
|
|
int64_t stride_value,
|
|
DataType::Type type,
|
|
IfCondition cmp) {
|
|
// Any loop of the general form:
|
|
//
|
|
// for (i = L; i <= U; i += S) // S > 0
|
|
// or for (i = L; i >= U; i += S) // S < 0
|
|
// .. i ..
|
|
//
|
|
// can be normalized into:
|
|
//
|
|
// for (n = 0; n < TC; n++) // where TC = (U + S - L) / S
|
|
// .. L + S * n ..
|
|
//
|
|
// taking the following into consideration:
|
|
//
|
|
// (1) Using the same precision, the TC (trip-count) expression should be interpreted as
|
|
// an unsigned entity, for example, as in the following loop that uses the full range:
|
|
// for (int i = INT_MIN; i < INT_MAX; i++) // TC = UINT_MAX
|
|
// (2) The TC is only valid if the loop is taken, otherwise TC = 0, as in:
|
|
// for (int i = 12; i < U; i++) // TC = 0 when U <= 12
|
|
// If this cannot be determined at compile-time, the TC is only valid within the
|
|
// loop-body proper, not the loop-header unless enforced with an explicit taken-test.
|
|
// (3) The TC is only valid if the loop is finite, otherwise TC has no value, as in:
|
|
// for (int i = 0; i <= U; i++) // TC = Inf when U = INT_MAX
|
|
// If this cannot be determined at compile-time, the TC is only valid when enforced
|
|
// with an explicit finite-test.
|
|
// (4) For loops which early-exits, the TC forms an upper bound, as in:
|
|
// for (int i = 0; i < 10 && ....; i++) // TC <= 10
|
|
InductionInfo* trip_count = upper_expr;
|
|
const bool is_taken = IsTaken(lower_expr, upper_expr, cmp);
|
|
const bool is_finite = IsFinite(upper_expr, stride_value, type, cmp);
|
|
const bool cancels = (cmp == kCondLT || cmp == kCondGT) && std::abs(stride_value) == 1;
|
|
if (!cancels) {
|
|
// Convert exclusive integral inequality into inclusive integral inequality,
|
|
// viz. condition i < U is i <= U - 1 and condition i > U is i >= U + 1.
|
|
if (cmp == kCondLT) {
|
|
trip_count = CreateInvariantOp(kSub, trip_count, CreateConstant(1, type));
|
|
} else if (cmp == kCondGT) {
|
|
trip_count = CreateInvariantOp(kAdd, trip_count, CreateConstant(1, type));
|
|
}
|
|
// Compensate for stride.
|
|
trip_count = CreateInvariantOp(kAdd, trip_count, stride_expr);
|
|
}
|
|
trip_count = CreateInvariantOp(
|
|
kDiv, CreateInvariantOp(kSub, trip_count, lower_expr), stride_expr);
|
|
// Assign the trip-count expression to the loop control. Clients that use the information
|
|
// should be aware that the expression is only valid under the conditions listed above.
|
|
InductionOp tcKind = kTripCountInBodyUnsafe; // needs both tests
|
|
if (is_taken && is_finite) {
|
|
tcKind = kTripCountInLoop; // needs neither test
|
|
} else if (is_finite) {
|
|
tcKind = kTripCountInBody; // needs taken-test
|
|
} else if (is_taken) {
|
|
tcKind = kTripCountInLoopUnsafe; // needs finite-test
|
|
}
|
|
InductionOp op = kNop;
|
|
switch (cmp) {
|
|
case kCondLT: op = kLT; break;
|
|
case kCondLE: op = kLE; break;
|
|
case kCondGT: op = kGT; break;
|
|
case kCondGE: op = kGE; break;
|
|
default: LOG(FATAL) << "CONDITION UNREACHABLE";
|
|
}
|
|
// Associate trip count with control instruction, rather than the condition (even
|
|
// though it's its use) since former provides a convenient use-free placeholder.
|
|
HInstruction* control = loop->GetHeader()->GetLastInstruction();
|
|
InductionInfo* taken_test = CreateInvariantOp(op, lower_expr, upper_expr);
|
|
DCHECK(control->IsIf());
|
|
AssignInfo(loop, control, CreateTripCount(tcKind, trip_count, taken_test, type));
|
|
}
|
|
|
|
bool HInductionVarAnalysis::IsTaken(InductionInfo* lower_expr,
|
|
InductionInfo* upper_expr,
|
|
IfCondition cmp) {
|
|
int64_t lower_value;
|
|
int64_t upper_value;
|
|
switch (cmp) {
|
|
case kCondLT:
|
|
return IsAtMost(lower_expr, &lower_value)
|
|
&& IsAtLeast(upper_expr, &upper_value)
|
|
&& lower_value < upper_value;
|
|
case kCondLE:
|
|
return IsAtMost(lower_expr, &lower_value)
|
|
&& IsAtLeast(upper_expr, &upper_value)
|
|
&& lower_value <= upper_value;
|
|
case kCondGT:
|
|
return IsAtLeast(lower_expr, &lower_value)
|
|
&& IsAtMost(upper_expr, &upper_value)
|
|
&& lower_value > upper_value;
|
|
case kCondGE:
|
|
return IsAtLeast(lower_expr, &lower_value)
|
|
&& IsAtMost(upper_expr, &upper_value)
|
|
&& lower_value >= upper_value;
|
|
default:
|
|
LOG(FATAL) << "CONDITION UNREACHABLE";
|
|
UNREACHABLE();
|
|
}
|
|
}
|
|
|
|
bool HInductionVarAnalysis::IsFinite(InductionInfo* upper_expr,
|
|
int64_t stride_value,
|
|
DataType::Type type,
|
|
IfCondition cmp) {
|
|
int64_t min = DataType::MinValueOfIntegralType(type);
|
|
int64_t max = DataType::MaxValueOfIntegralType(type);
|
|
// Some rules under which it is certain at compile-time that the loop is finite.
|
|
int64_t value;
|
|
switch (cmp) {
|
|
case kCondLT:
|
|
return stride_value == 1 ||
|
|
(IsAtMost(upper_expr, &value) && value <= (max - stride_value + 1));
|
|
case kCondLE:
|
|
return (IsAtMost(upper_expr, &value) && value <= (max - stride_value));
|
|
case kCondGT:
|
|
return stride_value == -1 ||
|
|
(IsAtLeast(upper_expr, &value) && value >= (min - stride_value - 1));
|
|
case kCondGE:
|
|
return (IsAtLeast(upper_expr, &value) && value >= (min - stride_value));
|
|
default:
|
|
LOG(FATAL) << "CONDITION UNREACHABLE";
|
|
UNREACHABLE();
|
|
}
|
|
}
|
|
|
|
bool HInductionVarAnalysis::FitsNarrowerControl(InductionInfo* lower_expr,
|
|
InductionInfo* upper_expr,
|
|
int64_t stride_value,
|
|
DataType::Type type,
|
|
IfCondition cmp) {
|
|
int64_t min = DataType::MinValueOfIntegralType(type);
|
|
int64_t max = DataType::MaxValueOfIntegralType(type);
|
|
// Inclusive test need one extra.
|
|
if (stride_value != 1 && stride_value != -1) {
|
|
return false; // non-unit stride
|
|
} else if (cmp == kCondLE) {
|
|
max--;
|
|
} else if (cmp == kCondGE) {
|
|
min++;
|
|
}
|
|
// Do both bounds fit the range?
|
|
int64_t value = 0;
|
|
return IsAtLeast(lower_expr, &value) && value >= min &&
|
|
IsAtMost(lower_expr, &value) && value <= max &&
|
|
IsAtLeast(upper_expr, &value) && value >= min &&
|
|
IsAtMost(upper_expr, &value) && value <= max;
|
|
}
|
|
|
|
bool HInductionVarAnalysis::RewriteBreakLoop(HLoopInformation* loop,
|
|
HBasicBlock* body,
|
|
int64_t stride_value,
|
|
DataType::Type type) {
|
|
// Only accept unit stride.
|
|
if (std::abs(stride_value) != 1) {
|
|
return false;
|
|
}
|
|
// Simple terminating i != U condition, used nowhere else.
|
|
HIf* ifs = loop->GetHeader()->GetLastInstruction()->AsIf();
|
|
HInstruction* cond = ifs->InputAt(0);
|
|
if (ifs->GetPrevious() != cond || !cond->HasOnlyOneNonEnvironmentUse()) {
|
|
return false;
|
|
}
|
|
int c = LookupInfo(loop, cond->InputAt(0))->induction_class == kLinear ? 0 : 1;
|
|
HInstruction* index = cond->InputAt(c);
|
|
HInstruction* upper = cond->InputAt(1 - c);
|
|
// Safe to rewrite into i <= U?
|
|
IfCondition cmp = stride_value > 0 ? kCondLE : kCondGE;
|
|
if (!index->IsPhi() || !IsFinite(LookupInfo(loop, upper), stride_value, type, cmp)) {
|
|
return false;
|
|
}
|
|
// Body consists of update to index i only, used nowhere else.
|
|
if (body->GetSuccessors().size() != 1 ||
|
|
body->GetSingleSuccessor() != loop->GetHeader() ||
|
|
!body->GetPhis().IsEmpty() ||
|
|
body->GetInstructions().IsEmpty() ||
|
|
body->GetFirstInstruction() != index->InputAt(1) ||
|
|
!body->GetFirstInstruction()->HasOnlyOneNonEnvironmentUse() ||
|
|
!body->GetFirstInstruction()->GetNext()->IsGoto()) {
|
|
return false;
|
|
}
|
|
// Always taken or guarded by enclosing condition.
|
|
if (!IsTaken(LookupInfo(loop, index)->op_b, LookupInfo(loop, upper), cmp) &&
|
|
!IsGuardedBy(loop, cmp, index->InputAt(0), upper)) {
|
|
return false;
|
|
}
|
|
// Test if break-loop body can be written, and do so on success.
|
|
if (RewriteBreakLoopBody(loop, body, cond, index, upper, /*rewrite*/ false)) {
|
|
RewriteBreakLoopBody(loop, body, cond, index, upper, /*rewrite*/ true);
|
|
} else {
|
|
return false;
|
|
}
|
|
// Rewrite condition in HIR.
|
|
if (ifs->IfTrueSuccessor() != body) {
|
|
cmp = (cmp == kCondLE) ? kCondGT : kCondLT;
|
|
}
|
|
HInstruction* rep = nullptr;
|
|
switch (cmp) {
|
|
case kCondLT: rep = new (graph_->GetAllocator()) HLessThan(index, upper); break;
|
|
case kCondGT: rep = new (graph_->GetAllocator()) HGreaterThan(index, upper); break;
|
|
case kCondLE: rep = new (graph_->GetAllocator()) HLessThanOrEqual(index, upper); break;
|
|
case kCondGE: rep = new (graph_->GetAllocator()) HGreaterThanOrEqual(index, upper); break;
|
|
default: LOG(FATAL) << cmp; UNREACHABLE();
|
|
}
|
|
loop->GetHeader()->ReplaceAndRemoveInstructionWith(cond, rep);
|
|
return true;
|
|
}
|
|
|
|
//
|
|
// Helper methods.
|
|
//
|
|
|
|
void HInductionVarAnalysis::AssignInfo(HLoopInformation* loop,
|
|
HInstruction* instruction,
|
|
InductionInfo* info) {
|
|
auto it = induction_.find(loop);
|
|
if (it == induction_.end()) {
|
|
it = induction_.Put(loop,
|
|
ArenaSafeMap<HInstruction*, InductionInfo*>(
|
|
std::less<HInstruction*>(),
|
|
graph_->GetAllocator()->Adapter(kArenaAllocInductionVarAnalysis)));
|
|
}
|
|
it->second.Put(instruction, info);
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::LookupInfo(HLoopInformation* loop,
|
|
HInstruction* instruction) {
|
|
auto it = induction_.find(loop);
|
|
if (it != induction_.end()) {
|
|
auto loop_it = it->second.find(instruction);
|
|
if (loop_it != it->second.end()) {
|
|
return loop_it->second;
|
|
}
|
|
}
|
|
if (loop->IsDefinedOutOfTheLoop(instruction)) {
|
|
InductionInfo* info = CreateInvariantFetch(instruction);
|
|
AssignInfo(loop, instruction, info);
|
|
return info;
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::CreateConstant(int64_t value,
|
|
DataType::Type type) {
|
|
HInstruction* constant;
|
|
switch (type) {
|
|
case DataType::Type::kFloat64: constant = graph_->GetDoubleConstant(value); break;
|
|
case DataType::Type::kFloat32: constant = graph_->GetFloatConstant(value); break;
|
|
case DataType::Type::kInt64: constant = graph_->GetLongConstant(value); break;
|
|
default: constant = graph_->GetIntConstant(value); break;
|
|
}
|
|
return CreateInvariantFetch(constant);
|
|
}
|
|
|
|
HInductionVarAnalysis::InductionInfo* HInductionVarAnalysis::CreateSimplifiedInvariant(
|
|
InductionOp op,
|
|
InductionInfo* a,
|
|
InductionInfo* b) {
|
|
// Perform some light-weight simplifications during construction of a new invariant.
|
|
// This often safes memory and yields a more concise representation of the induction.
|
|
// More exhaustive simplifications are done by later phases once induction nodes are
|
|
// translated back into HIR code (e.g. by loop optimizations or BCE).
|
|
int64_t value = -1;
|
|
if (IsExact(a, &value)) {
|
|
if (value == 0) {
|
|
// Simplify 0 + b = b, 0 ^ b = b, 0 * b = 0.
|
|
if (op == kAdd || op == kXor) {
|
|
return b;
|
|
} else if (op == kMul) {
|
|
return a;
|
|
}
|
|
} else if (op == kMul) {
|
|
// Simplify 1 * b = b, -1 * b = -b
|
|
if (value == 1) {
|
|
return b;
|
|
} else if (value == -1) {
|
|
return CreateSimplifiedInvariant(kNeg, nullptr, b);
|
|
}
|
|
}
|
|
}
|
|
if (IsExact(b, &value)) {
|
|
if (value == 0) {
|
|
// Simplify a + 0 = a, a - 0 = a, a ^ 0 = a, a * 0 = 0, -0 = 0.
|
|
if (op == kAdd || op == kSub || op == kXor) {
|
|
return a;
|
|
} else if (op == kMul || op == kNeg) {
|
|
return b;
|
|
}
|
|
} else if (op == kMul || op == kDiv) {
|
|
// Simplify a * 1 = a, a / 1 = a, a * -1 = -a, a / -1 = -a
|
|
if (value == 1) {
|
|
return a;
|
|
} else if (value == -1) {
|
|
return CreateSimplifiedInvariant(kNeg, nullptr, a);
|
|
}
|
|
}
|
|
} else if (b->operation == kNeg) {
|
|
// Simplify a + (-b) = a - b, a - (-b) = a + b, -(-b) = b.
|
|
if (op == kAdd) {
|
|
return CreateSimplifiedInvariant(kSub, a, b->op_b);
|
|
} else if (op == kSub) {
|
|
return CreateSimplifiedInvariant(kAdd, a, b->op_b);
|
|
} else if (op == kNeg) {
|
|
return b->op_b;
|
|
}
|
|
} else if (b->operation == kSub) {
|
|
// Simplify - (a - b) = b - a.
|
|
if (op == kNeg) {
|
|
return CreateSimplifiedInvariant(kSub, b->op_b, b->op_a);
|
|
}
|
|
}
|
|
return new (graph_->GetAllocator()) InductionInfo(
|
|
kInvariant, op, a, b, nullptr, ImplicitConversion(b->type));
|
|
}
|
|
|
|
HInstruction* HInductionVarAnalysis::GetShiftConstant(HLoopInformation* loop,
|
|
HInstruction* instruction,
|
|
InductionInfo* initial) {
|
|
DCHECK(instruction->IsShl() || instruction->IsShr() || instruction->IsUShr());
|
|
// Shift-rights are only the same as division for non-negative initial inputs.
|
|
// Otherwise we would round incorrectly.
|
|
if (initial != nullptr) {
|
|
int64_t value = -1;
|
|
if (!IsAtLeast(initial, &value) || value < 0) {
|
|
return nullptr;
|
|
}
|
|
}
|
|
// Obtain the constant needed to treat shift as equivalent multiplication or division.
|
|
// This yields an existing instruction if the constant is already there. Otherwise, this
|
|
// has a side effect on the HIR. The restriction on the shift factor avoids generating a
|
|
// negative constant (viz. 1 << 31 and 1L << 63 set the sign bit). The code assumes that
|
|
// generalization for shift factors outside [0,32) and [0,64) ranges is done earlier.
|
|
InductionInfo* b = LookupInfo(loop, instruction->InputAt(1));
|
|
int64_t value = -1;
|
|
if (IsExact(b, &value)) {
|
|
DataType::Type type = instruction->InputAt(0)->GetType();
|
|
if (type == DataType::Type::kInt32 && 0 <= value && value < 31) {
|
|
return graph_->GetIntConstant(1 << value);
|
|
}
|
|
if (type == DataType::Type::kInt64 && 0 <= value && value < 63) {
|
|
return graph_->GetLongConstant(1L << value);
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
void HInductionVarAnalysis::AssignCycle(HPhi* phi) {
|
|
ArenaSet<HInstruction*>* set = &cycles_.Put(phi, ArenaSet<HInstruction*>(
|
|
graph_->GetAllocator()->Adapter(kArenaAllocInductionVarAnalysis)))->second;
|
|
for (HInstruction* i : scc_) {
|
|
set->insert(i);
|
|
}
|
|
}
|
|
|
|
ArenaSet<HInstruction*>* HInductionVarAnalysis::LookupCycle(HPhi* phi) {
|
|
auto it = cycles_.find(phi);
|
|
if (it != cycles_.end()) {
|
|
return &it->second;
|
|
}
|
|
return nullptr;
|
|
}
|
|
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bool HInductionVarAnalysis::IsExact(InductionInfo* info, int64_t* value) {
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return InductionVarRange(this).IsConstant(info, InductionVarRange::kExact, value);
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}
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bool HInductionVarAnalysis::IsAtMost(InductionInfo* info, int64_t* value) {
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return InductionVarRange(this).IsConstant(info, InductionVarRange::kAtMost, value);
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}
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bool HInductionVarAnalysis::IsAtLeast(InductionInfo* info, int64_t* value) {
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return InductionVarRange(this).IsConstant(info, InductionVarRange::kAtLeast, value);
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}
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bool HInductionVarAnalysis::IsNarrowingLinear(InductionInfo* info) {
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return info != nullptr &&
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info->induction_class == kLinear &&
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(info->type == DataType::Type::kUint8 ||
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info->type == DataType::Type::kInt8 ||
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info->type == DataType::Type::kUint16 ||
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info->type == DataType::Type::kInt16 ||
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(info->type == DataType::Type::kInt32 && (info->op_a->type == DataType::Type::kInt64 ||
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info->op_b->type == DataType::Type::kInt64)));
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}
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bool HInductionVarAnalysis::InductionEqual(InductionInfo* info1,
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InductionInfo* info2) {
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// Test structural equality only, without accounting for simplifications.
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if (info1 != nullptr && info2 != nullptr) {
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return
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info1->induction_class == info2->induction_class &&
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info1->operation == info2->operation &&
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info1->fetch == info2->fetch &&
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info1->type == info2->type &&
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InductionEqual(info1->op_a, info2->op_a) &&
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InductionEqual(info1->op_b, info2->op_b);
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}
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// Otherwise only two nullptrs are considered equal.
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return info1 == info2;
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}
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std::string HInductionVarAnalysis::FetchToString(HInstruction* fetch) {
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DCHECK(fetch != nullptr);
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if (fetch->IsIntConstant()) {
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return std::to_string(fetch->AsIntConstant()->GetValue());
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} else if (fetch->IsLongConstant()) {
|
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return std::to_string(fetch->AsLongConstant()->GetValue());
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}
|
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return std::to_string(fetch->GetId()) + ":" + fetch->DebugName();
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|
}
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|
|
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std::string HInductionVarAnalysis::InductionToString(InductionInfo* info) {
|
|
if (info != nullptr) {
|
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if (info->induction_class == kInvariant) {
|
|
std::string inv = "(";
|
|
inv += InductionToString(info->op_a);
|
|
switch (info->operation) {
|
|
case kNop: inv += " @ "; break;
|
|
case kAdd: inv += " + "; break;
|
|
case kSub:
|
|
case kNeg: inv += " - "; break;
|
|
case kMul: inv += " * "; break;
|
|
case kDiv: inv += " / "; break;
|
|
case kRem: inv += " % "; break;
|
|
case kXor: inv += " ^ "; break;
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|
case kLT: inv += " < "; break;
|
|
case kLE: inv += " <= "; break;
|
|
case kGT: inv += " > "; break;
|
|
case kGE: inv += " >= "; break;
|
|
case kFetch: inv += FetchToString(info->fetch); break;
|
|
case kTripCountInLoop: inv += " (TC-loop) "; break;
|
|
case kTripCountInBody: inv += " (TC-body) "; break;
|
|
case kTripCountInLoopUnsafe: inv += " (TC-loop-unsafe) "; break;
|
|
case kTripCountInBodyUnsafe: inv += " (TC-body-unsafe) "; break;
|
|
}
|
|
inv += InductionToString(info->op_b);
|
|
inv += ")";
|
|
return inv;
|
|
} else {
|
|
if (info->induction_class == kLinear) {
|
|
DCHECK(info->operation == kNop);
|
|
return "(" + InductionToString(info->op_a) + " * i + " +
|
|
InductionToString(info->op_b) + "):" +
|
|
DataType::PrettyDescriptor(info->type);
|
|
} else if (info->induction_class == kPolynomial) {
|
|
DCHECK(info->operation == kNop);
|
|
return "poly(sum_lt(" + InductionToString(info->op_a) + ") + " +
|
|
InductionToString(info->op_b) + "):" +
|
|
DataType::PrettyDescriptor(info->type);
|
|
} else if (info->induction_class == kGeometric) {
|
|
DCHECK(info->operation == kMul || info->operation == kDiv);
|
|
DCHECK(info->fetch != nullptr);
|
|
return "geo(" + InductionToString(info->op_a) + " * " +
|
|
FetchToString(info->fetch) +
|
|
(info->operation == kMul ? " ^ i + " : " ^ -i + ") +
|
|
InductionToString(info->op_b) + "):" +
|
|
DataType::PrettyDescriptor(info->type);
|
|
} else if (info->induction_class == kWrapAround) {
|
|
DCHECK(info->operation == kNop);
|
|
return "wrap(" + InductionToString(info->op_a) + ", " +
|
|
InductionToString(info->op_b) + "):" +
|
|
DataType::PrettyDescriptor(info->type);
|
|
} else if (info->induction_class == kPeriodic) {
|
|
DCHECK(info->operation == kNop);
|
|
return "periodic(" + InductionToString(info->op_a) + ", " +
|
|
InductionToString(info->op_b) + "):" +
|
|
DataType::PrettyDescriptor(info->type);
|
|
}
|
|
}
|
|
}
|
|
return "";
|
|
}
|
|
|
|
} // namespace art
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