2714fd2399
This reverts commit r21712 TBR=danno@chromium.org Review URL: https://codereview.chromium.org/315843005 git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21715 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
59 lines
2.1 KiB
C++
59 lines
2.1 KiB
C++
// Copyright 2013 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "src/hydrogen-dehoist.h"
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namespace v8 {
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namespace internal {
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static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) {
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HValue* index = array_operation->GetKey()->ActualValue();
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if (!index->representation().IsSmiOrInteger32()) return;
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if (!index->IsAdd() && !index->IsSub()) return;
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HConstant* constant;
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HValue* subexpression;
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HBinaryOperation* binary_operation = HBinaryOperation::cast(index);
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if (binary_operation->left()->IsConstant() && index->IsAdd()) {
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subexpression = binary_operation->right();
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constant = HConstant::cast(binary_operation->left());
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} else if (binary_operation->right()->IsConstant()) {
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subexpression = binary_operation->left();
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constant = HConstant::cast(binary_operation->right());
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} else {
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return;
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}
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if (!constant->HasInteger32Value()) return;
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int32_t sign = binary_operation->IsSub() ? -1 : 1;
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int32_t value = constant->Integer32Value() * sign;
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// We limit offset values to 30 bits because we want to avoid the risk of
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// overflows when the offset is added to the object header size.
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if (value >= 1 << array_operation->MaxBaseOffsetBits() || value < 0) return;
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array_operation->SetKey(subexpression);
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if (binary_operation->HasNoUses()) {
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binary_operation->DeleteAndReplaceWith(NULL);
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}
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value <<= ElementsKindToShiftSize(array_operation->elements_kind());
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array_operation->IncreaseBaseOffset(static_cast<uint32_t>(value));
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array_operation->SetDehoisted(true);
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}
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void HDehoistIndexComputationsPhase::Run() {
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const ZoneList<HBasicBlock*>* blocks(graph()->blocks());
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for (int i = 0; i < blocks->length(); ++i) {
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for (HInstructionIterator it(blocks->at(i)); !it.Done(); it.Advance()) {
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HInstruction* instr = it.Current();
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if (instr->IsLoadKeyed()) {
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DehoistArrayIndex(HLoadKeyed::cast(instr));
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} else if (instr->IsStoreKeyed()) {
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DehoistArrayIndex(HStoreKeyed::cast(instr));
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}
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}
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}
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}
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} } // namespace v8::internal
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