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.
5 #include "src/hydrogen-dehoist.h"
6 #include "src/base/safe_math.h"
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;
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());
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;
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();
42 // Ensure that the array operation can add value to existing base offset
43 // without overflowing.
44 if (!array_operation->TryIncreaseBaseOffset(value)) return;
46 array_operation->SetKey(subexpression);
47 if (binary_operation->HasNoUses()) {
48 binary_operation->DeleteAndReplaceWith(NULL);
51 array_operation->SetDehoisted(true);
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));
69 } } // namespace v8::internal