| /* |
| * Copyright (C) 2012, 2013 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 "DFGAbstractState.h" |
| #include "DFGBasicBlock.h" |
| #include "DFGGraph.h" |
| #include "DFGInsertionSet.h" |
| #include "DFGPhase.h" |
| #include "GetByIdStatus.h" |
| #include "Operations.h" |
| #include "PutByIdStatus.h" |
| |
| namespace JSC { namespace DFG { |
| |
| class ConstantFoldingPhase : public Phase { |
| public: |
| ConstantFoldingPhase(Graph& graph) |
| : Phase(graph, "constant folding") |
| , m_state(graph) |
| , m_insertionSet(graph) |
| { |
| } |
| |
| bool run() |
| { |
| bool changed = false; |
| |
| for (BlockIndex blockIndex = 0; blockIndex < m_graph.m_blocks.size(); ++blockIndex) { |
| BasicBlock* block = m_graph.m_blocks[blockIndex].get(); |
| if (!block) |
| continue; |
| if (!block->cfaDidFinish) |
| changed |= paintUnreachableCode(blockIndex); |
| if (block->cfaFoundConstants) |
| changed |= foldConstants(blockIndex); |
| } |
| |
| return changed; |
| } |
| |
| private: |
| bool foldConstants(BlockIndex blockIndex) |
| { |
| #if DFG_ENABLE(DEBUG_PROPAGATION_VERBOSE) |
| dataLogF("Constant folding considering Block #%u.\n", blockIndex); |
| #endif |
| BasicBlock* block = m_graph.m_blocks[blockIndex].get(); |
| 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 eliminated = false; |
| |
| switch (node->op()) { |
| case CheckArgumentsNotCreated: { |
| if (!isEmptySpeculation( |
| m_state.variables().operand( |
| m_graph.argumentsRegisterFor(node->codeOrigin)).m_type)) |
| break; |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| |
| case CheckStructure: |
| case ForwardCheckStructure: |
| 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_currentKnownStructure.isSubsetOf(set)) { |
| m_state.execute(indexInBlock); // Catch the fact that we may filter on cell. |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| StructureAbstractValue& structureValue = value.m_futurePossibleStructure; |
| if (structureValue.isSubsetOf(set) |
| && structureValue.hasSingleton()) { |
| Structure* structure = structureValue.singleton(); |
| m_state.execute(indexInBlock); // Catch the fact that we may filter on cell. |
| node->convertToStructureTransitionWatchpoint(structure); |
| 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 CheckFunction: { |
| if (m_state.forNode(node->child1()).value() != node->function()) |
| break; |
| node->convertToPhantom(); |
| eliminated = true; |
| break; |
| } |
| |
| case GetById: |
| case GetByIdFlush: { |
| CodeOrigin codeOrigin = node->codeOrigin; |
| Edge childEdge = node->child1(); |
| Node* child = childEdge.node(); |
| unsigned identifierNumber = node->identifierNumber(); |
| |
| if (childEdge.useKind() != CellUse) |
| break; |
| |
| Structure* structure = m_state.forNode(child).bestProvenStructure(); |
| if (!structure) |
| break; |
| |
| bool needsWatchpoint = !m_state.forNode(child).m_currentKnownStructure.hasSingleton(); |
| |
| GetByIdStatus status = GetByIdStatus::computeFor( |
| globalData(), structure, codeBlock()->identifier(identifierNumber)); |
| |
| if (!status.isSimple()) { |
| // FIXME: We could handle prototype cases. |
| // https://bugs.webkit.org/show_bug.cgi?id=110386 |
| break; |
| } |
| |
| ASSERT(status.structureSet().size() == 1); |
| ASSERT(status.chain().isEmpty()); |
| ASSERT(status.structureSet().singletonStructure() == structure); |
| |
| // Now before we do anything else, push the CFA forward over the GetById |
| // and make sure we signal to the loop that it should continue and not |
| // do any eliminations. |
| m_state.execute(indexInBlock); |
| eliminated = true; |
| |
| if (needsWatchpoint) { |
| ASSERT(m_state.forNode(child).m_futurePossibleStructure.isSubsetOf(StructureSet(structure))); |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, StructureTransitionWatchpoint, codeOrigin, |
| OpInfo(structure), childEdge); |
| } else if (m_state.forNode(child).m_type & ~SpecCell) { |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, Phantom, codeOrigin, childEdge); |
| } |
| |
| childEdge.setUseKind(KnownCellUse); |
| |
| Edge propertyStorage; |
| |
| if (isInlineOffset(status.offset())) |
| propertyStorage = childEdge; |
| else { |
| propertyStorage = Edge(m_insertionSet.insertNode( |
| indexInBlock, SpecNone, GetButterfly, codeOrigin, childEdge)); |
| } |
| |
| node->convertToGetByOffset(m_graph.m_storageAccessData.size(), propertyStorage); |
| |
| StorageAccessData storageAccessData; |
| storageAccessData.offset = indexRelativeToBase(status.offset()); |
| storageAccessData.identifierNumber = identifierNumber; |
| m_graph.m_storageAccessData.append(storageAccessData); |
| break; |
| } |
| |
| case PutById: |
| case PutByIdDirect: { |
| CodeOrigin codeOrigin = node->codeOrigin; |
| Edge childEdge = node->child1(); |
| Node* child = childEdge.node(); |
| unsigned identifierNumber = node->identifierNumber(); |
| |
| ASSERT(childEdge.useKind() == CellUse); |
| |
| Structure* structure = m_state.forNode(child).bestProvenStructure(); |
| if (!structure) |
| break; |
| |
| bool needsWatchpoint = !m_state.forNode(child).m_currentKnownStructure.hasSingleton(); |
| |
| PutByIdStatus status = PutByIdStatus::computeFor( |
| globalData(), |
| m_graph.globalObjectFor(codeOrigin), |
| structure, |
| codeBlock()->identifier(identifierNumber), |
| node->op() == PutByIdDirect); |
| |
| if (!status.isSimpleReplace() && !status.isSimpleTransition()) |
| break; |
| |
| ASSERT(status.oldStructure() == structure); |
| |
| // Now before we do anything else, push the CFA forward over the PutById |
| // and make sure we signal to the loop that it should continue and not |
| // do any eliminations. |
| m_state.execute(indexInBlock); |
| eliminated = true; |
| |
| if (needsWatchpoint) { |
| ASSERT(m_state.forNode(child).m_futurePossibleStructure.isSubsetOf(StructureSet(structure))); |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, StructureTransitionWatchpoint, codeOrigin, |
| OpInfo(structure), childEdge); |
| } else if (m_state.forNode(child).m_type & ~SpecCell) { |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, Phantom, codeOrigin, childEdge); |
| } |
| |
| childEdge.setUseKind(KnownCellUse); |
| |
| StructureTransitionData* transitionData = 0; |
| if (status.isSimpleTransition()) { |
| transitionData = m_graph.addStructureTransitionData( |
| StructureTransitionData(structure, status.newStructure())); |
| |
| if (node->op() == PutById) { |
| if (!structure->storedPrototype().isNull()) { |
| addStructureTransitionCheck( |
| codeOrigin, indexInBlock, |
| structure->storedPrototype().asCell()); |
| } |
| |
| for (WriteBarrier<Structure>* it = status.structureChain()->head(); *it; ++it) { |
| JSValue prototype = (*it)->storedPrototype(); |
| if (prototype.isNull()) |
| continue; |
| ASSERT(prototype.isCell()); |
| addStructureTransitionCheck( |
| codeOrigin, indexInBlock, prototype.asCell()); |
| } |
| } |
| } |
| |
| Edge propertyStorage; |
| |
| if (isInlineOffset(status.offset())) |
| propertyStorage = childEdge; |
| else if (status.isSimpleReplace() || structure->outOfLineCapacity() == status.newStructure()->outOfLineCapacity()) { |
| propertyStorage = Edge(m_insertionSet.insertNode( |
| indexInBlock, SpecNone, GetButterfly, codeOrigin, childEdge)); |
| } else if (!structure->outOfLineCapacity()) { |
| ASSERT(status.newStructure()->outOfLineCapacity()); |
| ASSERT(!isInlineOffset(status.offset())); |
| propertyStorage = Edge(m_insertionSet.insertNode( |
| indexInBlock, SpecNone, AllocatePropertyStorage, |
| codeOrigin, OpInfo(transitionData), childEdge)); |
| } else { |
| ASSERT(structure->outOfLineCapacity()); |
| ASSERT(status.newStructure()->outOfLineCapacity() > structure->outOfLineCapacity()); |
| ASSERT(!isInlineOffset(status.offset())); |
| |
| propertyStorage = Edge(m_insertionSet.insertNode( |
| indexInBlock, SpecNone, ReallocatePropertyStorage, codeOrigin, |
| OpInfo(transitionData), childEdge, |
| Edge(m_insertionSet.insertNode( |
| indexInBlock, SpecNone, GetButterfly, codeOrigin, childEdge)))); |
| } |
| |
| if (status.isSimpleTransition()) { |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, PutStructure, codeOrigin, |
| OpInfo(transitionData), childEdge); |
| } |
| |
| node->convertToPutByOffset(m_graph.m_storageAccessData.size(), propertyStorage); |
| |
| StorageAccessData storageAccessData; |
| storageAccessData.offset = indexRelativeToBase(status.offset()); |
| storageAccessData.identifierNumber = identifierNumber; |
| m_graph.m_storageAccessData.append(storageAccessData); |
| break; |
| } |
| |
| default: |
| break; |
| } |
| |
| if (eliminated) { |
| changed = true; |
| continue; |
| } |
| |
| m_state.execute(indexInBlock); |
| if (!node->shouldGenerate() || m_state.didClobber() || node->hasConstant()) |
| continue; |
| JSValue value = m_state.forNode(node).value(); |
| if (!value) |
| continue; |
| |
| CodeOrigin codeOrigin = node->codeOrigin; |
| AdjacencyList children = node->children; |
| |
| if (node->op() == GetLocal) { |
| // GetLocals without a Phi child are guaranteed dead. We don't have to |
| // do anything about them. |
| if (!node->child1()) |
| continue; |
| |
| if (m_graph.m_form != LoadStore) { |
| VariableAccessData* variable = node->variableAccessData(); |
| Node* phi = node->child1().node(); |
| if (phi->op() == Phi |
| && block->variablesAtHead.operand(variable->local()) == phi |
| && block->variablesAtTail.operand(variable->local()) == node) { |
| |
| // Keep the graph threaded for easy cases. This is improves compile |
| // times. It would be correct to just dethread here. |
| |
| m_graph.convertToConstant(node, value); |
| Node* phantom = m_insertionSet.insertNode( |
| indexInBlock, SpecNone, PhantomLocal, codeOrigin, |
| OpInfo(variable), Edge(phi)); |
| block->variablesAtHead.operand(variable->local()) = phantom; |
| block->variablesAtTail.operand(variable->local()) = phantom; |
| |
| changed = true; |
| |
| continue; |
| } |
| |
| m_graph.dethread(); |
| } |
| } else |
| ASSERT(!node->hasVariableAccessData()); |
| |
| m_graph.convertToConstant(node, value); |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, Phantom, codeOrigin, children); |
| |
| changed = true; |
| } |
| m_state.reset(); |
| m_insertionSet.execute(block); |
| |
| return changed; |
| } |
| |
| #if !ASSERT_DISABLED |
| bool isCapturedAtOrAfter(BasicBlock* block, unsigned indexInBlock, int operand) |
| { |
| for (; indexInBlock < block->size(); ++indexInBlock) { |
| Node* node = block->at(indexInBlock); |
| if (!node->hasLocal()) |
| continue; |
| if (node->local() != operand) |
| continue; |
| if (node->variableAccessData()->isCaptured()) |
| return true; |
| } |
| return false; |
| } |
| #endif // !ASSERT_DISABLED |
| |
| void addStructureTransitionCheck(CodeOrigin codeOrigin, unsigned indexInBlock, JSCell* cell) |
| { |
| Node* weakConstant = m_insertionSet.insertNode( |
| indexInBlock, speculationFromValue(cell), WeakJSConstant, codeOrigin, OpInfo(cell)); |
| |
| if (cell->structure()->transitionWatchpointSetIsStillValid()) { |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, StructureTransitionWatchpoint, codeOrigin, |
| OpInfo(cell->structure()), Edge(weakConstant, CellUse)); |
| return; |
| } |
| |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, CheckStructure, codeOrigin, |
| OpInfo(m_graph.addStructureSet(cell->structure())), Edge(weakConstant, CellUse)); |
| } |
| |
| // This is necessary because the CFA may reach conclusions about constants based on its |
| // assumption that certain code must exit, but then those constants may lead future |
| // reexecutions of the CFA to believe that the same code will now no longer exit. Thus |
| // to ensure soundness, we must paint unreachable code as such, by inserting an |
| // unconditional ForceOSRExit wherever we find that a node would have always exited. |
| // This will only happen in cases where we are making static speculations, or we're |
| // making totally wrong speculations due to imprecision on the prediction propagator. |
| bool paintUnreachableCode(BlockIndex blockIndex) |
| { |
| bool changed = false; |
| |
| #if DFG_ENABLE(DEBUG_PROPAGATION_VERBOSE) |
| dataLogF("Painting unreachable code in Block #%u.\n", blockIndex); |
| #endif |
| BasicBlock* block = m_graph.m_blocks[blockIndex].get(); |
| m_state.beginBasicBlock(block); |
| |
| for (unsigned indexInBlock = 0; indexInBlock < block->size(); ++indexInBlock) { |
| m_state.execute(indexInBlock); |
| if (m_state.isValid()) |
| continue; |
| |
| Node* node = block->at(indexInBlock); |
| switch (node->op()) { |
| case Return: |
| case Throw: |
| case ThrowReferenceError: |
| case ForceOSRExit: |
| // Do nothing. These nodes will already do the right thing. |
| break; |
| |
| default: |
| m_insertionSet.insertNode( |
| indexInBlock, SpecNone, ForceOSRExit, node->codeOrigin); |
| changed = true; |
| break; |
| } |
| break; |
| } |
| m_state.reset(); |
| m_insertionSet.execute(block); |
| |
| return changed; |
| } |
| |
| AbstractState m_state; |
| InsertionSet m_insertionSet; |
| }; |
| |
| bool performConstantFolding(Graph& graph) |
| { |
| SamplingRegion samplingRegion("DFG Constant Folding Phase"); |
| return runPhase<ConstantFoldingPhase>(graph); |
| } |
| |
| } } // namespace JSC::DFG |
| |
| #endif // ENABLE(DFG_JIT) |
| |
| |
