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/crankshaft/hydrogen-dehoist.h" 6 7 #include "src/base/safe_math.h" 8 #include "src/objects-inl.h" 9 10 namespace v8 { 11 namespace internal { 12 13 static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) { 14 HValue* index = array_operation->GetKey()->ActualValue(); 15 if (!index->representation().IsSmiOrInteger32()) return; 16 if (!index->IsAdd() && !index->IsSub()) return; 17 18 HConstant* constant; 19 HValue* subexpression; 20 HBinaryOperation* binary_operation = HBinaryOperation::cast(index); 21 if (binary_operation->left()->IsConstant() && index->IsAdd()) { 22 subexpression = binary_operation->right(); 23 constant = HConstant::cast(binary_operation->left()); 24 } else if (binary_operation->right()->IsConstant()) { 25 subexpression = binary_operation->left(); 26 constant = HConstant::cast(binary_operation->right()); 27 } else { 28 return; 29 } 30 31 if (!constant->HasInteger32Value()) return; 32 v8::base::internal::CheckedNumeric<int32_t> checked_value = 33 constant->Integer32Value(); 34 int32_t sign = binary_operation->IsSub() ? -1 : 1; 35 checked_value = checked_value * sign; 36 37 // Multiply value by elements size, bailing out on overflow. 38 int32_t elements_kind_size = 39 1 << ElementsKindToShiftSize(array_operation->elements_kind()); 40 checked_value = checked_value * elements_kind_size; 41 if (!checked_value.IsValid()) return; 42 int32_t value = checked_value.ValueOrDie(); 43 if (value < 0) return; 44 45 // Ensure that the array operation can add value to existing base offset 46 // without overflowing. 47 if (!array_operation->TryIncreaseBaseOffset(value)) return; 48 49 array_operation->SetKey(subexpression); 50 if (binary_operation->HasNoUses()) { 51 binary_operation->DeleteAndReplaceWith(NULL); 52 } 53 54 array_operation->SetDehoisted(true); 55 } 56 57 58 void HDehoistIndexComputationsPhase::Run() { 59 const ZoneList<HBasicBlock*>* blocks(graph()->blocks()); 60 for (int i = 0; i < blocks->length(); ++i) { 61 for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) { 62 HInstruction* instr = it.Current(); 63 if (instr->IsLoadKeyed()) { 64 DehoistArrayIndex(HLoadKeyed::cast(instr)); 65 } else if (instr->IsStoreKeyed()) { 66 DehoistArrayIndex(HStoreKeyed::cast(instr)); 67 } 68 } 69 } 70 } 71 72 } // namespace internal 73 } // namespace v8 74
