bool run()
{
ASSERT(m_graph.m_form == ThreadedCPS);
ASSERT(m_graph.m_unificationState == LocallyUnified);
// Ensure that all Phi functions are unified.
for (BlockIndex blockIndex = m_graph.m_blocks.size(); blockIndex--;) {
BasicBlock* block = m_graph.m_blocks[blockIndex].get();
if (!block)
continue;
ASSERT(block->isReachable);
for (unsigned phiIndex = block->phis.size(); phiIndex--;) {
Node* phi = block->phis[phiIndex];
for (unsigned childIdx = 0; childIdx < AdjacencyList::Size; ++childIdx) {
if (!phi->children.child(childIdx))
break;
phi->variableAccessData()->unify(
phi->children.child(childIdx)->variableAccessData());
}
}
}
// Ensure that all predictions are fixed up based on the unification.
for (unsigned i = 0; i < m_graph.m_variableAccessData.size(); ++i) {
VariableAccessData* data = &m_graph.m_variableAccessData[i];
data->find()->predict(data->nonUnifiedPrediction());
data->find()->mergeIsCaptured(data->isCaptured());
data->find()->mergeStructureCheckHoistingFailed(data->structureCheckHoistingFailed());
data->find()->mergeShouldNeverUnbox(data->shouldNeverUnbox());
data->find()->mergeIsLoadedFrom(data->isLoadedFrom());
}
m_graph.m_unificationState = GloballyUnified;
return true;
}
bool run()
{
for (unsigned i = m_graph.m_variableAccessData.size(); i--;) {
VariableAccessData* variable = &m_graph.m_variableAccessData[i];
if (!variable->isRoot())
continue;
variable->clearVotes();
}
// Identify the set of variables that are always subject to the same structure
// checks. For now, only consider monomorphic structure checks (one structure).
for (BlockIndex blockIndex = 0; blockIndex < m_graph.m_blocks.size(); ++blockIndex) {
BasicBlock* block = m_graph.m_blocks[blockIndex].get();
if (!block)
continue;
for (unsigned indexInBlock = 0; indexInBlock < block->size(); ++indexInBlock) {
NodeIndex nodeIndex = block->at(indexInBlock);
Node& node = m_graph[nodeIndex];
if (!node.shouldGenerate())
continue;
switch (node.op()) {
case CheckStructure: {
Node& child = m_graph[node.child1()];
if (child.op() != GetLocal)
break;
VariableAccessData* variable = child.variableAccessData();
variable->vote(VoteStructureCheck);
if (variable->isCaptured() || variable->structureCheckHoistingFailed())
break;
if (!isCellSpeculation(variable->prediction()))
break;
noticeStructureCheck(variable, node.structureSet());
break;
}
case ForwardCheckStructure:
case ForwardStructureTransitionWatchpoint:
// We currently rely on the fact that we're the only ones who would
// insert this node.
ASSERT_NOT_REACHED();
break;
case GetByOffset:
case PutByOffset:
case PutStructure:
case StructureTransitionWatchpoint:
case AllocatePropertyStorage:
case ReallocatePropertyStorage:
case GetPropertyStorage:
case GetByVal:
case PutByVal:
case PutByValAlias:
case GetArrayLength:
case CheckArray:
case GetIndexedPropertyStorage:
case Phantom:
// Don't count these uses.
break;
default:
m_graph.vote(node, VoteOther);
break;
}
}
}
// Disable structure hoisting on variables that appear to mostly be used in
// contexts where it doesn't make sense.
for (unsigned i = m_graph.m_variableAccessData.size(); i--;) {
VariableAccessData* variable = &m_graph.m_variableAccessData[i];
if (!variable->isRoot())
continue;
if (variable->voteRatio() >= Options::structureCheckVoteRatioForHoisting())
continue;
HashMap<VariableAccessData*, CheckData>::iterator iter = m_map.find(variable);
if (iter == m_map.end())
continue;
#if DFG_ENABLE(DEBUG_PROPAGATION_VERBOSE)
dataLog("Zeroing the structure to hoist for %s because the ratio is %lf.\n",
m_graph.nameOfVariableAccessData(variable), variable->voteRatio());
#endif
iter->second.m_structure = 0;
}
// Identify the set of variables that are live across a structure clobber.
Operands<VariableAccessData*> live(
m_graph.m_blocks[0]->variablesAtTail.numberOfArguments(),
m_graph.m_blocks[0]->variablesAtTail.numberOfLocals());
for (BlockIndex blockIndex = 0; blockIndex < m_graph.m_blocks.size(); ++blockIndex) {
BasicBlock* block = m_graph.m_blocks[blockIndex].get();
if (!block)
continue;
ASSERT(live.numberOfArguments() == block->variablesAtTail.numberOfArguments());
ASSERT(live.numberOfLocals() == block->variablesAtTail.numberOfLocals());
for (unsigned i = live.size(); i--;) {
NodeIndex indexAtTail = block->variablesAtTail[i];
VariableAccessData* variable;
if (indexAtTail == NoNode)
variable = 0;
else
variable = m_graph[indexAtTail].variableAccessData();
live[i] = variable;
}
for (unsigned indexInBlock = block->size(); indexInBlock--;) {
NodeIndex nodeIndex = block->at(indexInBlock);
Node& node = m_graph[nodeIndex];
if (!node.shouldGenerate())
continue;
switch (node.op()) {
case GetLocal:
case Flush:
// This is a birth.
live.operand(node.local()) = node.variableAccessData();
break;
case SetLocal:
case SetArgument:
ASSERT(live.operand(node.local())); // Must be live.
ASSERT(live.operand(node.local()) == node.variableAccessData()); // Must have the variable we expected.
// This is a death.
live.operand(node.local()) = 0;
break;
// Use the CFA's notion of what clobbers the world.
case ValueAdd:
if (m_graph.addShouldSpeculateInteger(node))
break;
if (Node::shouldSpeculateNumber(m_graph[node.child1()], m_graph[node.child2()]))
break;
clobber(live);
break;
case CompareLess:
case CompareLessEq:
case CompareGreater:
case CompareGreaterEq:
case CompareEq: {
Node& left = m_graph[node.child1()];
Node& right = m_graph[node.child2()];
if (Node::shouldSpeculateInteger(left, right))
break;
if (Node::shouldSpeculateNumber(left, right))
break;
if (node.op() == CompareEq) {
if ((m_graph.isConstant(node.child1().index())
&& m_graph.valueOfJSConstant(node.child1().index()).isNull())
|| (m_graph.isConstant(node.child2().index())
&& m_graph.valueOfJSConstant(node.child2().index()).isNull()))
break;
if (Node::shouldSpeculateFinalObject(left, right))
break;
if (Node::shouldSpeculateArray(left, right))
break;
if (left.shouldSpeculateFinalObject() && right.shouldSpeculateFinalObjectOrOther())
break;
if (right.shouldSpeculateFinalObject() && left.shouldSpeculateFinalObjectOrOther())
break;
if (left.shouldSpeculateArray() && right.shouldSpeculateArrayOrOther())
break;
if (right.shouldSpeculateArray() && left.shouldSpeculateArrayOrOther())
break;
}
clobber(live);
break;
}
case GetByVal:
case PutByVal:
case PutByValAlias:
if (m_graph.byValIsPure(node))
break;
clobber(live);
break;
case GetMyArgumentsLengthSafe:
case GetMyArgumentByValSafe:
case GetById:
case GetByIdFlush:
case PutStructure:
case PhantomPutStructure:
case PutById:
case PutByIdDirect:
case Call:
case Construct:
case Resolve:
case ResolveBase:
case ResolveBaseStrictPut:
case ResolveGlobal:
clobber(live);
break;
default:
ASSERT(node.op() != Phi);
break;
}
}
}
bool changed = false;
#if DFG_ENABLE(DEBUG_PROPAGATION_VERBOSE)
for (HashMap<VariableAccessData*, CheckData>::iterator it = m_map.begin();
it != m_map.end(); ++it) {
if (!it->second.m_structure) {
dataLog("Not hoisting checks for %s because of heuristics.\n", m_graph.nameOfVariableAccessData(it->first));
continue;
}
if (it->second.m_isClobbered && !it->second.m_structure->transitionWatchpointSetIsStillValid()) {
dataLog("Not hoisting checks for %s because the structure is clobbered and has an invalid watchpoint set.\n", m_graph.nameOfVariableAccessData(it->first));
continue;
}
dataLog("Hoisting checks for %s\n", m_graph.nameOfVariableAccessData(it->first));
}
#endif // DFG_ENABLE(DEBUG_PROPAGATION_VERBOSE)
// Make changes:
// 1) If a variable's live range does not span a clobber, then inject structure
// checks before the SetLocal.
// 2) If a variable's live range spans a clobber but is watchpointable, then
// inject structure checks before the SetLocal and replace all other structure
// checks on that variable with structure transition watchpoints.
InsertionSet<NodeIndex> insertionSet;
for (BlockIndex blockIndex = 0; blockIndex < m_graph.m_blocks.size(); ++blockIndex) {
BasicBlock* block = m_graph.m_blocks[blockIndex].get();
if (!block)
continue;
for (unsigned indexInBlock = 0; indexInBlock < block->size(); ++indexInBlock) {
NodeIndex nodeIndex = block->at(indexInBlock);
Node& node = m_graph[nodeIndex];
// Be careful not to use 'node' after appending to the graph. In those switch
// cases where we need to append, we first carefully extract everything we need
// from the node, before doing any appending.
if (!node.shouldGenerate())
continue;
switch (node.op()) {
case SetArgument: {
ASSERT(!blockIndex);
// Insert a GetLocal and a CheckStructure immediately following this
// SetArgument, if the variable was a candidate for structure hoisting.
// If the basic block previously only had the SetArgument as its
// variable-at-tail, then replace it with this GetLocal.
VariableAccessData* variable = node.variableAccessData();
HashMap<VariableAccessData*, CheckData>::iterator iter = m_map.find(variable);
if (iter == m_map.end())
break;
if (!iter->second.m_structure)
break;
if (iter->second.m_isClobbered && !iter->second.m_structure->transitionWatchpointSetIsStillValid())
break;
node.ref();
CodeOrigin codeOrigin = node.codeOrigin;
Node getLocal(GetLocal, codeOrigin, OpInfo(variable), nodeIndex);
getLocal.predict(variable->prediction());
getLocal.ref();
NodeIndex getLocalIndex = m_graph.size();
m_graph.append(getLocal);
insertionSet.append(indexInBlock + 1, getLocalIndex);
Node checkStructure(CheckStructure, codeOrigin, OpInfo(m_graph.addStructureSet(iter->second.m_structure)), getLocalIndex);
checkStructure.ref();
NodeIndex checkStructureIndex = m_graph.size();
m_graph.append(checkStructure);
insertionSet.append(indexInBlock + 1, checkStructureIndex);
if (block->variablesAtTail.operand(variable->local()) == nodeIndex)
block->variablesAtTail.operand(variable->local()) = getLocalIndex;
m_graph.substituteGetLocal(*block, indexInBlock, variable, getLocalIndex);
changed = true;
break;
}
case SetLocal: {
VariableAccessData* variable = node.variableAccessData();
HashMap<VariableAccessData*, CheckData>::iterator iter = m_map.find(variable);
if (iter == m_map.end())
break;
if (!iter->second.m_structure)
break;
if (iter->second.m_isClobbered && !iter->second.m_structure->transitionWatchpointSetIsStillValid())
break;
// First insert a dead SetLocal to tell OSR that the child's value should
// be dropped into this bytecode variable if the CheckStructure decides
// to exit.
CodeOrigin codeOrigin = node.codeOrigin;
NodeIndex child1 = node.child1().index();
Node setLocal(SetLocal, codeOrigin, OpInfo(variable), child1);
NodeIndex setLocalIndex = m_graph.size();
m_graph.append(setLocal);
insertionSet.append(indexInBlock, setLocalIndex);
m_graph[child1].ref();
// Use a ForwardCheckStructure to indicate that we should exit to the
// next bytecode instruction rather than reexecuting the current one.
Node checkStructure(ForwardCheckStructure, codeOrigin, OpInfo(m_graph.addStructureSet(iter->second.m_structure)), child1);
checkStructure.ref();
NodeIndex checkStructureIndex = m_graph.size();
m_graph.append(checkStructure);
insertionSet.append(indexInBlock, checkStructureIndex);
changed = true;
break;
}
case CheckStructure: {
Node& child = m_graph[node.child1()];
if (child.op() != GetLocal)
break;
HashMap<VariableAccessData*, CheckData>::iterator iter = m_map.find(child.variableAccessData());
if (iter == m_map.end())
break;
if (!iter->second.m_structure)
break;
if (!iter->second.m_isClobbered) {
node.setOpAndDefaultFlags(Phantom);
ASSERT(node.refCount() == 1);
break;
}
if (!iter->second.m_structure->transitionWatchpointSetIsStillValid())
break;
ASSERT(iter->second.m_structure == node.structureSet().singletonStructure());
node.convertToStructureTransitionWatchpoint();
changed = true;
break;
}
default:
break;
}
}
insertionSet.execute(*block);
}
return changed;
}