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/*
* Copyright (C) 2015-2016 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 "DFGLiveCatchVariablePreservationPhase.h"
#if ENABLE(DFG_JIT)
#include "DFGBasicBlockInlines.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()
{
if (!m_graph.m_hasExceptionHandlers)
return true;
DFG_ASSERT(m_graph, nullptr, m_graph.m_form == LoadStore);
m_currentBlockLiveness.resize(m_graph.block(0)->variablesAtTail.numberOfLocals());
InsertionSet insertionSet(m_graph);
for (BasicBlock* block : m_graph.blocksInNaturalOrder()) {
handleBlock(block, insertionSet);
insertionSet.execute(block);
}
return true;
}
bool willCatchException(CodeOrigin origin)
{
unsigned bytecodeIndexToCheck = origin.bytecodeIndex;
m_currentBlockLiveness.clearAll();
while (1) {
InlineCallFrame* inlineCallFrame = origin.inlineCallFrame;
CodeBlock* codeBlock = m_graph.baselineCodeBlockFor(inlineCallFrame);
if (HandlerInfo* handler = codeBlock->handlerForBytecodeOffset(bytecodeIndexToCheck)) {
unsigned catchBytecodeIndex = handler->target;
m_graph.forAllLocalsLiveInBytecode(CodeOrigin(catchBytecodeIndex, inlineCallFrame), [&] (VirtualRegister operand) {
m_currentBlockLiveness[operand.toLocal()] = true;
});
return true;
}
if (!inlineCallFrame)
return false;
bytecodeIndexToCheck = inlineCallFrame->directCaller.bytecodeIndex;
origin = inlineCallFrame->directCaller;
}
}
void handleBlock(BasicBlock* block, InsertionSet& insertionSet)
{
// Because precise jump targets ensures that the start of a "try" block is its
// own basic block, we will never have two "try" statements in the same DFG
// basic block. Therefore, checking the first node in the block is sufficient
// to checking if we're in a try block.
if (!willCatchException(block->at(0)->origin.semantic))
return;
Operands<VariableAccessData*> currentBlockAccessData(block->variablesAtTail.numberOfArguments(), block->variablesAtTail.numberOfLocals(), nullptr);
HashSet<InlineCallFrame*> seenInlineCallFrames;
{
for (unsigned i = 0; i < block->size(); i++) {
Node* node = block->at(i);
bool isPrimordialSetArgument = node->op() == SetArgument && node->local().isArgument() && node == m_graph.m_arguments[node->local().toArgument()];
InlineCallFrame* inlineCallFrame = node->origin.semantic.inlineCallFrame;
if (inlineCallFrame)
seenInlineCallFrames.add(inlineCallFrame);
if (node->op() == SetLocal || (node->op() == SetArgument && !isPrimordialSetArgument)) {
VirtualRegister operand = node->local();
int stackOffset = inlineCallFrame ? inlineCallFrame->stackOffset : 0;
if ((operand.isLocal() && m_currentBlockLiveness[operand.toLocal()])
|| (operand.offset() == stackOffset + CallFrame::thisArgumentOffset())) {
VariableAccessData* variableAccessData = currentBlockAccessData.operand(operand);
if (!variableAccessData)
variableAccessData = newVariableAccessData(operand);
insertionSet.insertNode(i, SpecNone,
Flush, node->origin, OpInfo(variableAccessData));
}
}
if (node->accessesStack(m_graph))
currentBlockAccessData.operand(node->local()) = node->variableAccessData();
}
}
// Insert Flush for everything at the end of the block.
{
NodeOrigin origin = block->at(block->size() - 1)->origin;
auto preserveLivenessAtEndOfBlock = [&] (VirtualRegister operand, bool alwaysInsert) {
if ((operand.isLocal() && m_currentBlockLiveness[operand.toLocal()])
|| operand.isArgument()
|| alwaysInsert) {
VariableAccessData* accessData = currentBlockAccessData.operand(operand);
if (!accessData)
accessData = newVariableAccessData(operand);
currentBlockAccessData.operand(operand) = accessData;
insertionSet.insertNode(block->size(), SpecNone,
Flush, origin, OpInfo(accessData));
}
};
for (unsigned local = 0; local < block->variablesAtTail.numberOfLocals(); local++)
preserveLivenessAtEndOfBlock(virtualRegisterForLocal(local), false);
for (InlineCallFrame* inlineCallFrame : seenInlineCallFrames)
preserveLivenessAtEndOfBlock(VirtualRegister(inlineCallFrame->stackOffset + CallFrame::thisArgumentOffset()), true);
preserveLivenessAtEndOfBlock(VirtualRegister(CallFrame::thisArgumentOffset()), true);
}
}
VariableAccessData* newVariableAccessData(VirtualRegister operand)
{
ASSERT(!operand.isConstant());
m_graph.m_variableAccessData.append(VariableAccessData(operand));
return &m_graph.m_variableAccessData.last();
}
FastBitVector m_currentBlockLiveness;
};
bool performLiveCatchVariablePreservationPhase(Graph& graph)
{
return runPhase<LiveCatchVariablePreservationPhase>(graph);
}
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)
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