DFGVarargsForwardingPhase.cpp [plain text]
#include "config.h"
#include "DFGVarargsForwardingPhase.h"
#if ENABLE(DFG_JIT)
#include "ButterflyInlines.h"
#include "ClonedArguments.h"
#include "DFGArgumentsUtilities.h"
#include "DFGClobberize.h"
#include "DFGForAllKills.h"
#include "DFGGraph.h"
#include "DFGPhase.h"
#include <wtf/ListDump.h>
namespace JSC { namespace DFG {
namespace {
class VarargsForwardingPhase : public Phase {
static constexpr bool verbose = false;
public:
VarargsForwardingPhase(Graph& graph)
: Phase(graph, "varargs forwarding")
{
}
bool run()
{
DFG_ASSERT(m_graph, nullptr, m_graph.m_form != SSA);
if (verbose) {
dataLog("Graph before varargs forwarding:\n");
m_graph.dump();
}
m_changed = false;
for (BasicBlock* block : m_graph.blocksInNaturalOrder())
handleBlock(block);
return m_changed;
}
private:
void handleBlock(BasicBlock* block)
{
for (unsigned nodeIndex = 0; nodeIndex < block->size(); ++nodeIndex) {
Node* node = block->at(nodeIndex);
switch (node->op()) {
case CreateDirectArguments:
case CreateClonedArguments:
handleCandidate(block, nodeIndex);
break;
default:
break;
}
}
}
void handleCandidate(BasicBlock* block, unsigned candidateNodeIndex)
{
Node* candidate = block->at(candidateNodeIndex);
if (verbose)
dataLog("Handling candidate ", candidate, "\n");
Vector<Node*, 1> candidateButterflies;
unsigned lastUserIndex = candidateNodeIndex;
Vector<Operand, 2> relevantLocals; for (unsigned nodeIndex = candidateNodeIndex + 1; nodeIndex < block->size(); ++nodeIndex) {
Node* node = block->at(nodeIndex);
auto defaultEscape = [&] {
if (m_graph.uses(node, candidate)) {
if (verbose)
dataLog(" Escape at ", node, "\n");
return true;
}
return false;
};
bool validGetByOffset = false;
switch (node->op()) {
case MovHint:
if (node->child1() != candidate)
break;
lastUserIndex = nodeIndex;
if (!relevantLocals.contains(node->unlinkedOperand()))
relevantLocals.append(node->unlinkedOperand());
break;
case CheckVarargs:
case Check: {
bool sawEscape = false;
m_graph.doToChildren(
node,
[&] (Edge edge) {
if (edge == candidate) {
lastUserIndex = nodeIndex;
if (edge.willNotHaveCheck())
return;
if (alreadyChecked(edge.useKind(), SpecObject))
return;
sawEscape = true;
}
});
if (sawEscape) {
if (verbose)
dataLog(" Escape at ", node, "\n");
return;
}
break;
}
case VarargsLength:
case LoadVarargs:
if (m_graph.uses(node, candidate))
lastUserIndex = nodeIndex;
break;
case CallVarargs:
case ConstructVarargs:
case TailCallVarargs:
case TailCallVarargsInlinedCaller:
if (node->child1() == candidate || node->child2() == candidate) {
if (verbose)
dataLog(" Escape at ", node, "\n");
return;
}
if (node->child2() == candidate)
lastUserIndex = nodeIndex;
break;
case SetLocal:
if (node->child1() == candidate && node->variableAccessData()->isLoadedFrom()) {
if (verbose)
dataLog(" Escape at ", node, "\n");
return;
}
break;
case GetArrayLength: {
if (node->arrayMode().type() == Array::DirectArguments && node->child1() == candidate && node->child1()->op() == CreateDirectArguments) {
lastUserIndex = nodeIndex;
break;
}
if (defaultEscape())
return;
break;
}
case GetButterfly: {
if (node->child1() == candidate && candidate->op() == CreateClonedArguments) {
lastUserIndex = nodeIndex;
candidateButterflies.append(node);
break;
}
if (defaultEscape())
return;
break;
}
case FilterGetByStatus:
case FilterPutByIdStatus:
case FilterCallLinkStatus:
case FilterInByIdStatus:
case FilterDeleteByStatus:
break;
case GetByOffset: {
if (node->child1()->op() == GetButterfly
&& candidateButterflies.contains(node->child1().node())
&& node->child2() == candidate
&& node->storageAccessData().offset == clonedArgumentsLengthPropertyOffset) {
ASSERT(node->child1()->child1() == candidate);
ASSERT(isOutOfLineOffset(clonedArgumentsLengthPropertyOffset));
lastUserIndex = nodeIndex;
validGetByOffset = true;
break;
}
if (defaultEscape())
return;
break;
}
default:
if (defaultEscape())
return;
break;
}
if (!validGetByOffset) {
for (Node* butterfly : candidateButterflies) {
if (m_graph.uses(node, butterfly)) {
if (verbose)
dataLog(" Butterfly escaped at ", node, "\n");
return;
}
}
}
forAllKilledOperands(
m_graph, node, block->tryAt(nodeIndex + 1),
[&] (Operand operand) {
if (verbose)
dataLog(" Killing ", operand, " while we are interested in ", listDump(relevantLocals), "\n");
for (unsigned i = 0; i < relevantLocals.size(); ++i) {
if (operand == relevantLocals[i]) {
relevantLocals[i--] = relevantLocals.last();
relevantLocals.removeLast();
lastUserIndex = nodeIndex;
ASSERT(!relevantLocals.contains(operand));
break;
}
}
});
}
if (verbose)
dataLog("Selected lastUserIndex = ", lastUserIndex, ", ", block->at(lastUserIndex), "\n");
for (unsigned nodeIndex = candidateNodeIndex + 1; nodeIndex <= lastUserIndex; ++nodeIndex) {
Node* node = block->at(nodeIndex);
switch (node->op()) {
case MovHint:
case ZombieHint:
case KillStack:
if (argumentsInvolveStackSlot(candidate, node->unlinkedOperand())) {
if (verbose)
dataLog(" Interference at ", node, "\n");
return;
}
break;
case PutStack:
if (argumentsInvolveStackSlot(candidate, node->stackAccessData()->operand)) {
if (verbose)
dataLog(" Interference at ", node, "\n");
return;
}
break;
case SetLocal:
case Flush:
if (argumentsInvolveStackSlot(candidate, node->operand())) {
if (verbose)
dataLog(" Interference at ", node, "\n");
return;
}
break;
default: {
bool doesInterfere = false;
clobberize(
m_graph, node, NoOpClobberize(),
[&] (AbstractHeap heap) {
if (heap.kind() != Stack) {
ASSERT(!heap.overlaps(Stack));
return;
}
ASSERT(!heap.payload().isTop());
if (argumentsInvolveStackSlot(candidate, heap.operand()))
doesInterfere = true;
},
NoOpClobberize());
if (doesInterfere) {
if (verbose)
dataLog(" Interference at ", node, "\n");
return;
}
} }
}
if (verbose)
dataLog(" Will do forwarding!\n");
m_changed = true;
switch (candidate->op()) {
case CreateDirectArguments:
candidate->setOpAndDefaultFlags(PhantomDirectArguments);
break;
case CreateClonedArguments:
candidate->setOpAndDefaultFlags(PhantomClonedArguments);
break;
default:
DFG_CRASH(m_graph, candidate, "bad node type");
break;
}
InsertionSet insertionSet(m_graph);
for (unsigned nodeIndex = candidateNodeIndex + 1; nodeIndex <= lastUserIndex; ++nodeIndex) {
Node* node = block->at(nodeIndex);
switch (node->op()) {
case Check:
case CheckVarargs:
case MovHint:
case PutHint:
break;
case VarargsLength: {
if (node->argumentsChild() != candidate)
break;
node->convertToIdentityOn(emitCodeToGetArgumentsArrayLength(insertionSet, candidate, nodeIndex, node->origin, true));
break;
}
case LoadVarargs:
if (node->argumentsChild() != candidate)
break;
node->setOpAndDefaultFlags(ForwardVarargs);
break;
case CallVarargs:
if (node->child3() != candidate)
break;
node->setOpAndDefaultFlags(CallForwardVarargs);
break;
case ConstructVarargs:
if (node->child3() != candidate)
break;
node->setOpAndDefaultFlags(ConstructForwardVarargs);
break;
case TailCallVarargs:
if (node->child3() != candidate)
break;
node->setOpAndDefaultFlags(TailCallForwardVarargs);
break;
case TailCallVarargsInlinedCaller:
if (node->child3() != candidate)
break;
node->setOpAndDefaultFlags(TailCallForwardVarargsInlinedCaller);
break;
case SetLocal:
break;
case GetButterfly: {
if (node->child1().node() == candidate) {
ASSERT(candidateButterflies.contains(node));
node->child1() = Edge();
node->remove(m_graph);
}
break;
}
case FilterGetByStatus:
case FilterPutByIdStatus:
case FilterCallLinkStatus:
case FilterInByIdStatus:
case FilterDeleteByStatus:
if (node->child1().node() == candidate)
node->remove(m_graph);
break;
case GetByOffset: {
if (node->child2() == candidate) {
ASSERT(candidateButterflies.contains(node->child1().node())); ASSERT(node->storageAccessData().offset == clonedArgumentsLengthPropertyOffset);
node->convertToIdentityOn(
emitCodeToGetArgumentsArrayLength(insertionSet, candidate, nodeIndex, node->origin));
}
break;
}
case GetArrayLength:
if (node->arrayMode().type() == Array::DirectArguments && node->child1() == candidate) {
node->convertToIdentityOn(
emitCodeToGetArgumentsArrayLength(insertionSet, candidate, nodeIndex, node->origin));
}
break;
default:
if (!ASSERT_ENABLED)
break;
m_graph.doToChildren(
node,
[&] (Edge edge) {
DFG_ASSERT(m_graph, node, edge != candidate);
});
break;
}
}
insertionSet.execute(block);
}
bool m_changed;
};
}
bool performVarargsForwarding(Graph& graph)
{
return runPhase<VarargsForwardingPhase>(graph);
}
} }
#endif // ENABLE(DFG_JIT)