| /* |
| * Copyright (C) 2012, 2013, 2014 Apple Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
| * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "config.h" |
| #include "DFGConstantFoldingPhase.h" |
| |
| #if ENABLE(DFG_JIT) |
| |
| #include "DFGAbstractInterpreterInlines.h" |
| #include "DFGBasicBlock.h" |
| #include "DFGGraph.h" |
| #include "DFGInPlaceAbstractState.h" |
| #include "DFGInsertionSet.h" |
| #include "DFGPhase.h" |
| #include "GetByIdStatus.h" |
| #include "JSCInlines.h" |
| #include "PutByIdStatus.h" |
| |
| namespace JSC { namespace DFG { |
| |
| class ConstantFoldingPhase : public Phase { |
| public: |
| ConstantFoldingPhase(Graph& graph) |
| : Phase(graph, "constant folding") |
| , m_state(graph) |
| , m_interpreter(graph, m_state) |
| , m_insertionSet(graph) |
| { |
| } |
| |
| bool run() |
| { |
| bool changed = false; |
| |
| for (BlockIndex blockIndex = 0; blockIndex < m_graph.numBlocks(); ++blockIndex) { |
| BasicBlock* block = m_graph.block(blockIndex); |
| if (!block) |
| continue; |
| if (block->cfaFoundConstants) |
| changed |= foldConstants(block); |
| } |
| |
| if (changed && m_graph.m_form == SSA) { |
| // It's now possible that we have Upsilons pointed at JSConstants. Fix that. |
| for (BlockIndex blockIndex = m_graph.numBlocks(); blockIndex--;) { |
| BasicBlock* block = m_graph.block(blockIndex); |
| if (!block) |
| continue; |
| fixUpsilons(block); |
| } |
| } |
| |
| return changed; |
| } |
| |
| private: |
| bool foldConstants(BasicBlock* block) |
| { |
| bool changed = false; |
| m_state.beginBasicBlock(block); |
| for (unsigned indexInBlock = 0; indexInBlock < block->size(); ++indexInBlock) { |
| if (!m_state.isValid()) |
| break; |
| |
| Node* node = block->at(indexInBlock); |
| |
| bool alreadyHandled = false; |
| bool eliminated = false; |
| |
| switch (node->op()) { |
| case BooleanToNumber: { |
| if (node->child1().useKind() == UntypedUse |
| && !m_interpreter.needsTypeCheck(node->child1(), SpecBoolean)) |
| node->child1().setUseKind(BooleanUse); |
| break; |
| } |
| |
| case CheckArgumentsNotCreated: { |
| if (!isEmptySpeculation( |
| m_state.variables().operand( |
| m_graph.argumentsRegisterFor(node->origin.semantic)).m_type)) |
| break; |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| |
| case CheckStructure: |
| case ArrayifyToStructure: { |
| AbstractValue& value = m_state.forNode(node->child1()); |
| StructureSet set; |
| if (node->op() == ArrayifyToStructure) |
| set = node->structure(); |
| else |
| set = node->structureSet(); |
| if (value.m_structure.isSubsetOf(set)) { |
| m_interpreter.execute(indexInBlock); // Catch the fact that we may filter on cell. |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| break; |
| } |
| |
| case CheckStructureImmediate: { |
| AbstractValue& value = m_state.forNode(node->child1()); |
| StructureSet& set = node->structureSet(); |
| |
| if (value.value()) { |
| if (Structure* structure = jsDynamicCast<Structure*>(value.value())) { |
| if (set.contains(structure)) { |
| m_interpreter.execute(indexInBlock); |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| } |
| } |
| |
| if (PhiChildren* phiChildren = m_interpreter.phiChildren()) { |
| bool allGood = true; |
| phiChildren->forAllTransitiveIncomingValues( |
| node, |
| [&] (Node* incoming) { |
| if (Structure* structure = incoming->dynamicCastConstant<Structure*>()) { |
| if (set.contains(structure)) |
| return; |
| } |
| allGood = false; |
| }); |
| if (allGood) { |
| m_interpreter.execute(indexInBlock); |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| } |
| break; |
| } |
| |
| case CheckArray: |
| case Arrayify: { |
| if (!node->arrayMode().alreadyChecked(m_graph, node, m_state.forNode(node->child1()))) |
| break; |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| |
| case PutStructure: { |
| if (m_state.forNode(node->child1()).m_structure.onlyStructure() != node->transition()->next) |
| break; |
| |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| |
| case CheckCell: { |
| if (m_state.forNode(node->child1()).value() != node->cellOperand()->value()) |
| break; |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| |
| case CheckNotEmpty: { |
| if (m_state.forNode(node->child1()).m_type & SpecEmpty) |
| break; |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| |
| case CheckInBounds: { |
| JSValue left = m_state.forNode(node->child1()).value(); |
| JSValue right = m_state.forNode(node->child2()).value(); |
| if (left && right && left.isInt32() && right.isInt32() |
| && static_cast<uint32_t>(left.asInt32()) < static_cast<uint32_t>(right.asInt32())) { |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| |
| break; |
| } |
| |
| case MultiGetByOffset: { |
| Edge baseEdge = node->child1(); |
| Node* base = baseEdge.node(); |
| MultiGetByOffsetData& data = node->multiGetByOffsetData(); |
| |
| // First prune the variants, then check if the MultiGetByOffset can be |
| // strength-reduced to a GetByOffset. |
| |
| AbstractValue baseValue = m_state.forNode(base); |
| |
| m_interpreter.execute(indexInBlock); // Push CFA over this node after we get the state before. |
| alreadyHandled = true; // Don't allow the default constant folder to do things to this. |
| |
| for (unsigned i = 0; i < data.variants.size(); ++i) { |
| GetByIdVariant& variant = data.variants[i]; |
| variant.structureSet().filter(baseValue); |
| if (variant.structureSet().isEmpty()) { |
| data.variants[i--] = data.variants.last(); |
| data.variants.removeLast(); |
| changed = true; |
| } |
| } |
| |
| if (data.variants.size() != 1) |
| break; |
| |
| emitGetByOffset( |
| indexInBlock, node, baseValue, data.variants[0], data.identifierNumber); |
| changed = true; |
| break; |
| } |
| |
| case MultiPutByOffset: { |
| Edge baseEdge = node->child1(); |
| Node* base = baseEdge.node(); |
| MultiPutByOffsetData& data = node->multiPutByOffsetData(); |
| |
| AbstractValue baseValue = m_state.forNode(base); |
| |
| m_interpreter.execute(indexInBlock); // Push CFA over this node after we get the state before. |
| alreadyHandled = true; // Don't allow the default constant folder to do things to this. |
| |
| |
| for (unsigned i = 0; i < data.variants.size(); ++i) { |
| PutByIdVariant& variant = data.variants[i]; |
| variant.oldStructure().filter(baseValue); |
| |
| if (variant.oldStructure().isEmpty()) { |
| data.variants[i--] = data.variants.last(); |
| data.variants.removeLast(); |
| changed = true; |
| continue; |
| } |
| |
| if (variant.kind() == PutByIdVariant::Transition |
| && variant.oldStructure().onlyStructure() == variant.newStructure()) { |
| variant = PutByIdVariant::replace( |
| variant.oldStructure(), |
| variant.offset()); |
| changed = true; |
| } |
| } |
| |
| if (data.variants.size() != 1) |
| break; |
| |
| emitPutByOffset( |
| indexInBlock, node, baseValue, data.variants[0], data.identifierNumber); |
| changed = true; |
| break; |
| } |
| |
| case GetById: |
| case GetByIdFlush: { |
| Edge childEdge = node->child1(); |
| Node* child = childEdge.node(); |
| unsigned identifierNumber = node->identifierNumber(); |
| |
| AbstractValue baseValue = m_state.forNode(child); |
| |
| m_interpreter.execute(indexInBlock); // Push CFA over this node after we get the state before. |
| alreadyHandled = true; // Don't allow the default constant folder to do things to this. |
| |
| if (baseValue.m_structure.isTop() || baseValue.m_structure.isClobbered() |
| || (node->child1().useKind() == UntypedUse || (baseValue.m_type & ~SpecCell))) |
| break; |
| |
| GetByIdStatus status = GetByIdStatus::computeFor( |
| baseValue.m_structure.set(), m_graph.identifiers()[identifierNumber]); |
| if (!status.isSimple()) |
| break; |
| |
| for (unsigned i = status.numVariants(); i--;) { |
| if (!status[i].constantChecks().isEmpty() |
| || status[i].alternateBase()) { |
| // FIXME: We could handle prototype cases. |
| // https://bugs.webkit.org/show_bug.cgi?id=110386 |
| break; |
| } |
| } |
| |
| if (status.numVariants() == 1) { |
| emitGetByOffset(indexInBlock, node, baseValue, status[0], identifierNumber); |
| changed = true; |
| break; |
| } |
| |
| if (!isFTL(m_graph.m_plan.mode)) |
| break; |
| |
| MultiGetByOffsetData* data = m_graph.m_multiGetByOffsetData.add(); |
| data->variants = status.variants(); |
| data->identifierNumber = identifierNumber; |
| node->convertToMultiGetByOffset(data); |
| changed = true; |
| break; |
| } |
| |
| case PutById: |
| case PutByIdDirect: |
| case PutByIdFlush: { |
| NodeOrigin origin = node->origin; |
| Edge childEdge = node->child1(); |
| Node* child = childEdge.node(); |
| unsigned identifierNumber = node->identifierNumber(); |
| |
| ASSERT(childEdge.useKind() == CellUse); |
| |
| AbstractValue baseValue = m_state.forNode(child); |
| |
| m_interpreter.execute(indexInBlock); // Push CFA over this node after we get the state before. |
| alreadyHandled = true; // Don't allow the default constant folder to do things to this. |
| |
| if (baseValue.m_structure.isTop() || baseValue.m_structure.isClobbered()) |
| break; |
| |
| PutByIdStatus status = PutByIdStatus::computeFor( |
| m_graph.globalObjectFor(origin.semantic), |
| baseValue.m_structure.set(), |
| m_graph.identifiers()[identifierNumber], |
| node->op() == PutByIdDirect); |
| |
| if (!status.isSimple()) |
| break; |
| |
| ASSERT(status.numVariants()); |
| |
| if (status.numVariants() > 1 && !isFTL(m_graph.m_plan.mode)) |
| break; |
| |
| changed = true; |
| |
| for (unsigned i = status.numVariants(); i--;) |
| addChecks(origin, indexInBlock, status[i].constantChecks()); |
| |
| if (status.numVariants() == 1) { |
| emitPutByOffset(indexInBlock, node, baseValue, status[0], identifierNumber); |
| break; |
| } |
| |
| ASSERT(isFTL(m_graph.m_plan.mode)); |
| |
| MultiPutByOffsetData* data = m_graph.m_multiPutByOffsetData.add(); |
| data->variants = status.variants(); |
| data->identifierNumber = identifierNumber; |
| node->convertToMultiPutByOffset(data); |
| break; |
| } |
| |
| case ToPrimitive: { |
| if (m_state.forNode(node->child1()).m_type & ~(SpecFullNumber | SpecBoolean | SpecString | SpecCellOther)) |
| break; |
| |
| node->convertToIdentity(); |
| changed = true; |
| break; |
| } |
| |
| case GetMyArgumentByVal: { |
| InlineCallFrame* inlineCallFrame = node->origin.semantic.inlineCallFrame; |
| JSValue value = m_state.forNode(node->child1()).m_value; |
| if (inlineCallFrame && value && value.isInt32()) { |
| int32_t index = value.asInt32(); |
| if (index >= 0 |
| && static_cast<size_t>(index + 1) < inlineCallFrame->arguments.size()) { |
| // Roll the interpreter over this. |
| m_interpreter.execute(indexInBlock); |
| eliminated = true; |
| |
| int operand = |
| inlineCallFrame->stackOffset + |
| m_graph.baselineCodeBlockFor(inlineCallFrame)->argumentIndexAfterCapture(index); |
| |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, CheckArgumentsNotCreated, node->origin); |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, Phantom, node->origin, node->children); |
| |
| if (m_graph.m_form == SSA) |
| node->convertToGetStack(m_graph.m_stackAccessData.add(VirtualRegister(operand), FlushedJSValue)); |
| else |
| node->convertToGetLocalUnlinked(VirtualRegister(operand)); |
| break; |
| } |
| } |
| |
| break; |
| } |
| |
| case Check: { |
| alreadyHandled = true; |
| m_interpreter.execute(indexInBlock); |
| for (unsigned i = 0; i < AdjacencyList::Size; ++i) { |
| Edge edge = node->children.child(i); |
| if (!edge) |
| break; |
| if (edge.isProved() || edge.willNotHaveCheck()) { |
| node->children.removeEdge(i--); |
| changed = true; |
| } |
| } |
| break; |
| } |
| |
| default: |
| break; |
| } |
| |
| if (eliminated) { |
| changed = true; |
| continue; |
| } |
| |
| if (alreadyHandled) |
| continue; |
| |
| m_interpreter.execute(indexInBlock); |
| if (!m_state.isValid()) { |
| // If we invalidated then we shouldn't attempt to constant-fold. Here's an |
| // example: |
| // |
| // c: JSConstant(4.2) |
| // x: ValueToInt32(Check:Int32:@const) |
| // |
| // It would be correct for an analysis to assume that execution cannot |
| // proceed past @x. Therefore, constant-folding @x could be rather bad. But, |
| // the CFA may report that it found a constant even though it also reported |
| // that everything has been invalidated. This will only happen in a couple of |
| // the constant folding cases; most of them are also separately defensive |
| // about such things. |
| break; |
| } |
| if (!node->shouldGenerate() || m_state.didClobber() || node->hasConstant()) |
| continue; |
| |
| // Interesting fact: this freezing that we do right here may turn an fragile value into |
| // a weak value. See DFGValueStrength.h. |
| FrozenValue* value = m_graph.freeze(m_state.forNode(node).value()); |
| if (!*value) |
| continue; |
| |
| NodeOrigin origin = node->origin; |
| AdjacencyList children = node->children; |
| |
| m_graph.convertToConstant(node, value); |
| if (!children.isEmpty()) { |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, Phantom, origin, children); |
| } |
| |
| changed = true; |
| } |
| m_state.reset(); |
| m_insertionSet.execute(block); |
| |
| return changed; |
| } |
| |
| void emitGetByOffset(unsigned indexInBlock, Node* node, const AbstractValue& baseValue, const GetByIdVariant& variant, unsigned identifierNumber) |
| { |
| NodeOrigin origin = node->origin; |
| Edge childEdge = node->child1(); |
| |
| addBaseCheck(indexInBlock, node, baseValue, variant.structureSet()); |
| |
| JSValue baseForLoad; |
| if (variant.alternateBase()) |
| baseForLoad = variant.alternateBase(); |
| else |
| baseForLoad = baseValue.m_value; |
| if (JSValue value = m_graph.tryGetConstantProperty(baseForLoad, variant.baseStructure(), variant.offset())) { |
| m_graph.convertToConstant(node, m_graph.freeze(value)); |
| return; |
| } |
| |
| if (variant.alternateBase()) { |
| Node* child = m_insertionSet.insertConstant(indexInBlock, origin, variant.alternateBase()); |
| childEdge = Edge(child, KnownCellUse); |
| } else |
| childEdge.setUseKind(KnownCellUse); |
| |
| Edge propertyStorage; |
| |
| if (isInlineOffset(variant.offset())) |
| propertyStorage = childEdge; |
| else { |
| propertyStorage = Edge(m_insertionSet.insertNode( |
| indexInBlock, SpecNone, GetButterfly, origin, childEdge)); |
| } |
| |
| StorageAccessData& data = *m_graph.m_storageAccessData.add(); |
| data.offset = variant.offset(); |
| data.identifierNumber = identifierNumber; |
| |
| node->convertToGetByOffset(data, propertyStorage); |
| } |
| |
| void emitPutByOffset(unsigned indexInBlock, Node* node, const AbstractValue& baseValue, const PutByIdVariant& variant, unsigned identifierNumber) |
| { |
| NodeOrigin origin = node->origin; |
| Edge childEdge = node->child1(); |
| |
| addBaseCheck(indexInBlock, node, baseValue, variant.oldStructure()); |
| |
| childEdge.setUseKind(KnownCellUse); |
| |
| Transition* transition = 0; |
| if (variant.kind() == PutByIdVariant::Transition) { |
| transition = m_graph.m_transitions.add( |
| variant.oldStructureForTransition(), variant.newStructure()); |
| } |
| |
| Edge propertyStorage; |
| |
| if (isInlineOffset(variant.offset())) |
| propertyStorage = childEdge; |
| else if (!variant.reallocatesStorage()) { |
| propertyStorage = Edge(m_insertionSet.insertNode( |
| indexInBlock, SpecNone, GetButterfly, origin, childEdge)); |
| } else if (!variant.oldStructureForTransition()->outOfLineCapacity()) { |
| ASSERT(variant.newStructure()->outOfLineCapacity()); |
| ASSERT(!isInlineOffset(variant.offset())); |
| Node* allocatePropertyStorage = m_insertionSet.insertNode( |
| indexInBlock, SpecNone, AllocatePropertyStorage, |
| origin, OpInfo(transition), childEdge); |
| m_insertionSet.insertNode(indexInBlock, SpecNone, StoreBarrier, origin, Edge(node->child1().node(), KnownCellUse)); |
| propertyStorage = Edge(allocatePropertyStorage); |
| } else { |
| ASSERT(variant.oldStructureForTransition()->outOfLineCapacity()); |
| ASSERT(variant.newStructure()->outOfLineCapacity() > variant.oldStructureForTransition()->outOfLineCapacity()); |
| ASSERT(!isInlineOffset(variant.offset())); |
| |
| Node* reallocatePropertyStorage = m_insertionSet.insertNode( |
| indexInBlock, SpecNone, ReallocatePropertyStorage, origin, |
| OpInfo(transition), childEdge, |
| Edge(m_insertionSet.insertNode( |
| indexInBlock, SpecNone, GetButterfly, origin, childEdge))); |
| m_insertionSet.insertNode(indexInBlock, SpecNone, StoreBarrier, origin, Edge(node->child1().node(), KnownCellUse)); |
| propertyStorage = Edge(reallocatePropertyStorage); |
| } |
| |
| StorageAccessData& data = *m_graph.m_storageAccessData.add(); |
| data.offset = variant.offset(); |
| data.identifierNumber = identifierNumber; |
| |
| node->convertToPutByOffset(data, propertyStorage); |
| |
| if (variant.kind() == PutByIdVariant::Transition) { |
| // FIXME: PutStructure goes last until we fix either |
| // https://bugs.webkit.org/show_bug.cgi?id=142921 or |
| // https://bugs.webkit.org/show_bug.cgi?id=142924. |
| m_insertionSet.insertNode( |
| indexInBlock + 1, SpecNone, PutStructure, origin, OpInfo(transition), childEdge); |
| } |
| } |
| |
| void addBaseCheck( |
| unsigned indexInBlock, Node* node, const AbstractValue& baseValue, const StructureSet& set) |
| { |
| if (!baseValue.m_structure.isSubsetOf(set)) { |
| // Arises when we prune MultiGetByOffset. We could have a |
| // MultiGetByOffset with a single variant that checks for structure S, |
| // and the input has structures S and T, for example. |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, CheckStructure, node->origin, |
| OpInfo(m_graph.addStructureSet(set)), node->child1()); |
| return; |
| } |
| |
| if (baseValue.m_type & ~SpecCell) { |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, Phantom, node->origin, node->child1()); |
| } |
| } |
| |
| void addChecks( |
| NodeOrigin origin, unsigned indexInBlock, const ConstantStructureCheckVector& checks) |
| { |
| for (unsigned i = 0; i < checks.size(); ++i) { |
| addStructureTransitionCheck( |
| origin, indexInBlock, checks[i].constant(), checks[i].structure()); |
| } |
| } |
| |
| void addStructureTransitionCheck(NodeOrigin origin, unsigned indexInBlock, JSCell* cell, Structure* structure) |
| { |
| if (m_graph.registerStructure(cell->structure()) == StructureRegisteredAndWatched) |
| return; |
| |
| m_graph.registerStructure(structure); |
| |
| Node* weakConstant = m_insertionSet.insertNode( |
| indexInBlock, speculationFromValue(cell), JSConstant, origin, |
| OpInfo(m_graph.freeze(cell))); |
| |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, CheckStructure, origin, |
| OpInfo(m_graph.addStructureSet(structure)), Edge(weakConstant, CellUse)); |
| } |
| |
| void fixUpsilons(BasicBlock* block) |
| { |
| for (unsigned nodeIndex = block->size(); nodeIndex--;) { |
| Node* node = block->at(nodeIndex); |
| if (node->op() != Upsilon) |
| continue; |
| switch (node->phi()->op()) { |
| case Phi: |
| break; |
| case JSConstant: |
| case DoubleConstant: |
| case Int52Constant: |
| node->convertToPhantom(); |
| break; |
| default: |
| DFG_CRASH(m_graph, node, "Bad Upsilon phi() pointer"); |
| break; |
| } |
| } |
| } |
| |
| InPlaceAbstractState m_state; |
| AbstractInterpreter<InPlaceAbstractState> m_interpreter; |
| InsertionSet m_insertionSet; |
| }; |
| |
| bool performConstantFolding(Graph& graph) |
| { |
| SamplingRegion samplingRegion("DFG Constant Folding Phase"); |
| return runPhase<ConstantFoldingPhase>(graph); |
| } |
| |
| } } // namespace JSC::DFG |
| |
| #endif // ENABLE(DFG_JIT) |
| |
| |
