| // Copyright 2013 the V8 project authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "src/hydrogen-dehoist.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) { |
| HValue* index = array_operation->GetKey()->ActualValue(); |
| if (!index->representation().IsSmiOrInteger32()) return; |
| if (!index->IsAdd() && !index->IsSub()) return; |
| |
| HConstant* constant; |
| HValue* subexpression; |
| HBinaryOperation* binary_operation = HBinaryOperation::cast(index); |
| if (binary_operation->left()->IsConstant() && index->IsAdd()) { |
| subexpression = binary_operation->right(); |
| constant = HConstant::cast(binary_operation->left()); |
| } else if (binary_operation->right()->IsConstant()) { |
| subexpression = binary_operation->left(); |
| constant = HConstant::cast(binary_operation->right()); |
| } else { |
| return; |
| } |
| |
| if (!constant->HasInteger32Value()) return; |
| int32_t sign = binary_operation->IsSub() ? -1 : 1; |
| int32_t value = constant->Integer32Value() * sign; |
| // We limit offset values to 30 bits because we want to avoid the risk of |
| // overflows when the offset is added to the object header size. |
| if (value >= 1 << array_operation->MaxBaseOffsetBits() || value < 0) return; |
| array_operation->SetKey(subexpression); |
| if (binary_operation->HasNoUses()) { |
| binary_operation->DeleteAndReplaceWith(NULL); |
| } |
| value <<= ElementsKindToShiftSize(array_operation->elements_kind()); |
| array_operation->IncreaseBaseOffset(static_cast<uint32_t>(value)); |
| array_operation->SetDehoisted(true); |
| } |
| |
| |
| void HDehoistIndexComputationsPhase::Run() { |
| const ZoneList<HBasicBlock*>* blocks(graph()->blocks()); |
| for (int i = 0; i < blocks->length(); ++i) { |
| for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) { |
| HInstruction* instr = it.Current(); |
| if (instr->IsLoadKeyed()) { |
| DehoistArrayIndex(HLoadKeyed::cast(instr)); |
| } else if (instr->IsStoreKeyed()) { |
| DehoistArrayIndex(HStoreKeyed::cast(instr)); |
| } |
| } |
| } |
| } |
| |
| } } // namespace v8::internal |