Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 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 | |
| 9 | namespace v8 { |
| 10 | namespace internal { |
| 11 | |
| 12 | static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) { |
| 13 | HValue* index = array_operation->GetKey()->ActualValue(); |
| 14 | if (!index->representation().IsSmiOrInteger32()) return; |
| 15 | if (!index->IsAdd() && !index->IsSub()) return; |
| 16 | |
| 17 | HConstant* constant; |
| 18 | HValue* subexpression; |
| 19 | HBinaryOperation* binary_operation = HBinaryOperation::cast(index); |
| 20 | if (binary_operation->left()->IsConstant() && index->IsAdd()) { |
| 21 | subexpression = binary_operation->right(); |
| 22 | constant = HConstant::cast(binary_operation->left()); |
| 23 | } else if (binary_operation->right()->IsConstant()) { |
| 24 | subexpression = binary_operation->left(); |
| 25 | constant = HConstant::cast(binary_operation->right()); |
| 26 | } else { |
| 27 | return; |
| 28 | } |
| 29 | |
| 30 | if (!constant->HasInteger32Value()) return; |
| 31 | v8::base::internal::CheckedNumeric<int32_t> checked_value = |
| 32 | constant->Integer32Value(); |
| 33 | int32_t sign = binary_operation->IsSub() ? -1 : 1; |
| 34 | checked_value = checked_value * sign; |
| 35 | |
| 36 | // Multiply value by elements size, bailing out on overflow. |
| 37 | int32_t elements_kind_size = |
| 38 | 1 << ElementsKindToShiftSize(array_operation->elements_kind()); |
| 39 | checked_value = checked_value * elements_kind_size; |
| 40 | if (!checked_value.IsValid()) return; |
| 41 | int32_t value = checked_value.ValueOrDie(); |
| 42 | if (value < 0) return; |
| 43 | |
| 44 | // Ensure that the array operation can add value to existing base offset |
| 45 | // without overflowing. |
| 46 | if (!array_operation->TryIncreaseBaseOffset(value)) return; |
| 47 | |
| 48 | array_operation->SetKey(subexpression); |
| 49 | if (binary_operation->HasNoUses()) { |
| 50 | binary_operation->DeleteAndReplaceWith(NULL); |
| 51 | } |
| 52 | |
| 53 | array_operation->SetDehoisted(true); |
| 54 | } |
| 55 | |
| 56 | |
| 57 | void HDehoistIndexComputationsPhase::Run() { |
| 58 | const ZoneList<HBasicBlock*>* blocks(graph()->blocks()); |
| 59 | for (int i = 0; i < blocks->length(); ++i) { |
| 60 | for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) { |
| 61 | HInstruction* instr = it.Current(); |
| 62 | if (instr->IsLoadKeyed()) { |
| 63 | DehoistArrayIndex(HLoadKeyed::cast(instr)); |
| 64 | } else if (instr->IsStoreKeyed()) { |
| 65 | DehoistArrayIndex(HStoreKeyed::cast(instr)); |
| 66 | } |
| 67 | } |
| 68 | } |
| 69 | } |
| 70 | |
| 71 | } // namespace internal |
| 72 | } // namespace v8 |