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
9namespace v8 {
10namespace internal {
11
12static 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
57void 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
73