DFGLiveCatchVariablePreservationPhase.cpp [plain text]
#include "config.h"
#include "DFGLiveCatchVariablePreservationPhase.h"
#if ENABLE(DFG_JIT)
#include "DFGBasicBlockInlines.h"
#include "DFGBlockSet.h"
#include "DFGGraph.h"
#include "DFGInsertionSet.h"
#include "DFGPhase.h"
#include "FullBytecodeLiveness.h"
#include "JSCInlines.h"
namespace JSC { namespace DFG {
class LiveCatchVariablePreservationPhase : public Phase {
public:
LiveCatchVariablePreservationPhase(Graph& graph)
: Phase(graph, "live catch variable preservation phase")
{
}
bool run()
{
DFG_ASSERT(m_graph, nullptr, m_graph.m_form == LoadStore);
if (!m_graph.m_hasExceptionHandlers)
return false;
InsertionSet insertionSet(m_graph);
if (m_graph.m_hasExceptionHandlers) {
for (BasicBlock* block : m_graph.blocksInNaturalOrder()) {
handleBlockForTryCatch(block, insertionSet);
insertionSet.execute(block);
}
}
return true;
}
bool isValidFlushLocation(BasicBlock* startingBlock, unsigned index, VirtualRegister operand)
{
Vector<BasicBlock*, 4> worklist;
BlockSet seen;
auto addPredecessors = [&] (BasicBlock* block) {
for (BasicBlock* predecessor : block->predecessors) {
bool isNewEntry = seen.add(predecessor);
if (isNewEntry)
worklist.append(predecessor);
}
};
auto flushIsDefinitelyInvalid = [&] (BasicBlock* block, unsigned index) {
bool allGood = false;
for (unsigned i = index; i--; ) {
if (block->at(i)->accessesStack(m_graph) && block->at(i)->local() == operand) {
allGood = true;
break;
}
}
if (allGood)
return false;
if (block->predecessors.isEmpty()) {
return true;
}
addPredecessors(block);
return false;
};
if (flushIsDefinitelyInvalid(startingBlock, index))
return false;
while (!worklist.isEmpty()) {
BasicBlock* block = worklist.takeLast();
if (flushIsDefinitelyInvalid(block, block->size()))
return false;
}
return true;
}
void handleBlockForTryCatch(BasicBlock* block, InsertionSet& insertionSet)
{
HandlerInfo* currentExceptionHandler = nullptr;
FastBitVector liveAtCatchHead;
liveAtCatchHead.resize(m_graph.block(0)->variablesAtTail.numberOfLocals());
HandlerInfo* cachedHandlerResult;
CodeOrigin cachedCodeOrigin;
auto catchHandler = [&] (CodeOrigin origin) -> HandlerInfo* {
ASSERT(origin);
if (origin == cachedCodeOrigin)
return cachedHandlerResult;
unsigned bytecodeIndexToCheck = origin.bytecodeIndex;
cachedCodeOrigin = origin;
while (1) {
InlineCallFrame* inlineCallFrame = origin.inlineCallFrame;
CodeBlock* codeBlock = m_graph.baselineCodeBlockFor(inlineCallFrame);
if (HandlerInfo* handler = codeBlock->handlerForBytecodeOffset(bytecodeIndexToCheck)) {
liveAtCatchHead.clearAll();
unsigned catchBytecodeIndex = handler->target;
m_graph.forAllLocalsLiveInBytecode(CodeOrigin(catchBytecodeIndex, inlineCallFrame), [&] (VirtualRegister operand) {
liveAtCatchHead[operand.toLocal()] = true;
});
cachedHandlerResult = handler;
break;
}
if (!inlineCallFrame) {
cachedHandlerResult = nullptr;
break;
}
bytecodeIndexToCheck = inlineCallFrame->directCaller.bytecodeIndex;
origin = inlineCallFrame->directCaller;
}
return cachedHandlerResult;
};
Operands<VariableAccessData*> currentBlockAccessData(block->variablesAtTail.numberOfArguments(), block->variablesAtTail.numberOfLocals(), nullptr);
HashSet<InlineCallFrame*> seenInlineCallFrames;
auto flushEverything = [&] (NodeOrigin origin, unsigned index) {
RELEASE_ASSERT(currentExceptionHandler);
auto flush = [&] (VirtualRegister operand, bool alwaysInsert) {
if ((operand.isLocal() && liveAtCatchHead[operand.toLocal()])
|| operand.isArgument()
|| alwaysInsert) {
ASSERT(isValidFlushLocation(block, index, operand));
VariableAccessData* accessData = currentBlockAccessData.operand(operand);
if (!accessData)
accessData = newVariableAccessData(operand);
currentBlockAccessData.operand(operand) = accessData;
insertionSet.insertNode(index, SpecNone,
Flush, origin, OpInfo(accessData));
}
};
for (unsigned local = 0; local < block->variablesAtTail.numberOfLocals(); local++)
flush(virtualRegisterForLocal(local), false);
for (InlineCallFrame* inlineCallFrame : seenInlineCallFrames)
flush(VirtualRegister(inlineCallFrame->stackOffset + CallFrame::thisArgumentOffset()), true);
flush(VirtualRegister(CallFrame::thisArgumentOffset()), true);
seenInlineCallFrames.clear();
};
for (unsigned nodeIndex = 0; nodeIndex < block->size(); nodeIndex++) {
Node* node = block->at(nodeIndex);
{
HandlerInfo* newHandler = catchHandler(node->origin.semantic);
if (newHandler != currentExceptionHandler && currentExceptionHandler)
flushEverything(node->origin, nodeIndex);
currentExceptionHandler = newHandler;
}
if (currentExceptionHandler && (node->op() == SetLocal || node->op() == SetArgument)) {
InlineCallFrame* inlineCallFrame = node->origin.semantic.inlineCallFrame;
if (inlineCallFrame)
seenInlineCallFrames.add(inlineCallFrame);
VirtualRegister operand = node->local();
int stackOffset = inlineCallFrame ? inlineCallFrame->stackOffset : 0;
if ((operand.isLocal() && liveAtCatchHead[operand.toLocal()])
|| operand.isArgument()
|| (operand.offset() == stackOffset + CallFrame::thisArgumentOffset())) {
ASSERT(isValidFlushLocation(block, nodeIndex, operand));
VariableAccessData* variableAccessData = currentBlockAccessData.operand(operand);
if (!variableAccessData)
variableAccessData = newVariableAccessData(operand);
insertionSet.insertNode(nodeIndex, SpecNone,
Flush, node->origin, OpInfo(variableAccessData));
}
}
if (node->accessesStack(m_graph))
currentBlockAccessData.operand(node->local()) = node->variableAccessData();
}
if (currentExceptionHandler) {
NodeOrigin origin = block->at(block->size() - 1)->origin;
flushEverything(origin, block->size());
}
}
VariableAccessData* newVariableAccessData(VirtualRegister operand)
{
ASSERT(!operand.isConstant());
m_graph.m_variableAccessData.append(VariableAccessData(operand));
return &m_graph.m_variableAccessData.last();
}
};
bool performLiveCatchVariablePreservationPhase(Graph& graph)
{
return runPhase<LiveCatchVariablePreservationPhase>(graph);
}
} }
#endif // ENABLE(DFG_JIT)