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// Copyright 2013 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/crankshaft/hydrogen-dehoist.h"
#include "src/base/safe_math.h"
#include "src/objects-inl.h"
namespace v8 {
namespace internal {
static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) {
HValue* index = array_operation->GetKey()->ActualValue();
if (!index->representation().IsSmiOrInteger32()) return;
if (!index->IsAdd() && !index->IsSub()) return;
HConstant* constant;
HValue* subexpression;
HBinaryOperation* binary_operation = HBinaryOperation::cast(index);
if (binary_operation->left()->IsConstant() && index->IsAdd()) {
subexpression = binary_operation->right();
constant = HConstant::cast(binary_operation->left());
} else if (binary_operation->right()->IsConstant()) {
subexpression = binary_operation->left();
constant = HConstant::cast(binary_operation->right());
} else {
return;
}
if (!constant->HasInteger32Value()) return;
v8::base::internal::CheckedNumeric<int32_t> checked_value =
constant->Integer32Value();
int32_t sign = binary_operation->IsSub() ? -1 : 1;
checked_value = checked_value * sign;
// Multiply value by elements size, bailing out on overflow.
int32_t elements_kind_size =
1 << ElementsKindToShiftSize(array_operation->elements_kind());
checked_value = checked_value * elements_kind_size;
if (!checked_value.IsValid()) return;
int32_t value = checked_value.ValueOrDie();
if (value < 0) return;
// Ensure that the array operation can add value to existing base offset
// without overflowing.
if (!array_operation->TryIncreaseBaseOffset(value)) return;
array_operation->SetKey(subexpression);
if (binary_operation->HasNoUses()) {
binary_operation->DeleteAndReplaceWith(NULL);
}
array_operation->SetDehoisted(true);
}
void HDehoistIndexComputationsPhase::Run() {
const ZoneList<HBasicBlock*>* blocks(graph()->blocks());
for (int i = 0; i < blocks->length(); ++i) {
for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) {
HInstruction* instr = it.Current();
if (instr->IsLoadKeyed()) {
DehoistArrayIndex(HLoadKeyed::cast(instr));
} else if (instr->IsStoreKeyed()) {
DehoistArrayIndex(HStoreKeyed::cast(instr));
}
}
}
}
} // namespace internal
} // namespace v8
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