1 // Copyright 2013 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "src/hydrogen-dehoist.h" 6 #include "src/base/safe_math.h" 7 8 namespace v8 { 9 namespace internal { 10 11 static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) { 12 HValue* index = array_operation->GetKey()->ActualValue(); 13 if (!index->representation().IsSmiOrInteger32()) return; 14 if (!index->IsAdd() && !index->IsSub()) return; 15 16 HConstant* constant; 17 HValue* subexpression; 18 HBinaryOperation* binary_operation = HBinaryOperation::cast(index); 19 if (binary_operation->left()->IsConstant() && index->IsAdd()) { 20 subexpression = binary_operation->right(); 21 constant = HConstant::cast(binary_operation->left()); 22 } else if (binary_operation->right()->IsConstant()) { 23 subexpression = binary_operation->left(); 24 constant = HConstant::cast(binary_operation->right()); 25 } else { 26 return; 27 } 28 29 if (!constant->HasInteger32Value()) return; 30 int32_t sign = binary_operation->IsSub() ? -1 : 1; 31 int32_t value = constant->Integer32Value() * sign; 32 if (value < 0) return; 33 34 // Multiply value by elements size, bailing out on overflow. 35 int32_t elements_kind_size = 36 1 << ElementsKindToShiftSize(array_operation->elements_kind()); 37 v8::base::internal::CheckedNumeric<int32_t> multiply_result = value; 38 multiply_result = multiply_result * elements_kind_size; 39 if (!multiply_result.IsValid()) return; 40 value = multiply_result.ValueOrDie(); 41 42 // Ensure that the array operation can add value to existing base offset 43 // without overflowing. 44 if (!array_operation->TryIncreaseBaseOffset(value)) return; 45 46 array_operation->SetKey(subexpression); 47 if (binary_operation->HasNoUses()) { 48 binary_operation->DeleteAndReplaceWith(NULL); 49 } 50 51 array_operation->SetDehoisted(true); 52 } 53 54 55 void HDehoistIndexComputationsPhase::Run() { 56 const ZoneList<HBasicBlock*>* blocks(graph()->blocks()); 57 for (int i = 0; i < blocks->length(); ++i) { 58 for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) { 59 HInstruction* instr = it.Current(); 60 if (instr->IsLoadKeyed()) { 61 DehoistArrayIndex(HLoadKeyed::cast(instr)); 62 } else if (instr->IsStoreKeyed()) { 63 DehoistArrayIndex(HStoreKeyed::cast(instr)); 64 } 65 } 66 } 67 } 68 69 } } // namespace v8::internal 70
