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/*
* Copyright (C) 2013-2018 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 "DFGStackLayoutPhase.h"
#if ENABLE(DFG_JIT)
#include "DFGGraph.h"
#include "DFGPhase.h"
#include "DFGValueSource.h"
#include "JSCInlines.h"
namespace JSC { namespace DFG {
class StackLayoutPhase : public Phase {
static const bool verbose = false;
public:
StackLayoutPhase(Graph& graph)
: Phase(graph, "stack layout")
{
}
bool run()
{
// This enumerates the locals that we actually care about and packs them. So for example
// if we use local 1, 3, 4, 5, 7, then we remap them: 1->0, 3->1, 4->2, 5->3, 7->4. We
// treat a variable as being "used" if there exists an access to it (SetLocal, GetLocal,
// Flush, PhantomLocal).
BitVector usedLocals;
// Collect those variables that are used from IR.
bool hasNodesThatNeedFixup = false;
for (BlockIndex blockIndex = m_graph.numBlocks(); blockIndex--;) {
BasicBlock* block = m_graph.block(blockIndex);
if (!block)
continue;
for (unsigned nodeIndex = block->size(); nodeIndex--;) {
Node* node = block->at(nodeIndex);
switch (node->op()) {
case GetLocal:
case SetLocal:
case Flush:
case PhantomLocal: {
VariableAccessData* variable = node->variableAccessData();
if (variable->local().isArgument())
break;
usedLocals.set(variable->local().toLocal());
break;
}
case LoadVarargs:
case ForwardVarargs: {
LoadVarargsData* data = node->loadVarargsData();
if (data->count.isLocal())
usedLocals.set(data->count.toLocal());
if (data->start.isLocal()) {
// This part really relies on the contiguity of stack layout
// assignments.
ASSERT(VirtualRegister(data->start.offset() + data->limit - 1).isLocal());
for (unsigned i = data->limit; i--;)
usedLocals.set(VirtualRegister(data->start.offset() + i).toLocal());
} // the else case shouldn't happen.
hasNodesThatNeedFixup = true;
break;
}
case PutStack:
case GetStack: {
StackAccessData* stack = node->stackAccessData();
if (stack->local.isArgument())
break;
usedLocals.set(stack->local.toLocal());
break;
}
default:
break;
}
}
}
for (InlineCallFrameSet::iterator iter = m_graph.m_plan.inlineCallFrames()->begin(); !!iter; ++iter) {
InlineCallFrame* inlineCallFrame = *iter;
if (inlineCallFrame->isVarargs()) {
usedLocals.set(VirtualRegister(
CallFrameSlot::argumentCount + inlineCallFrame->stackOffset).toLocal());
}
for (unsigned argument = inlineCallFrame->argumentsWithFixup.size(); argument--;) {
usedLocals.set(VirtualRegister(
virtualRegisterForArgument(argument).offset() +
inlineCallFrame->stackOffset).toLocal());
}
}
Vector<unsigned> allocation(usedLocals.size());
m_graph.m_nextMachineLocal = codeBlock()->calleeSaveSpaceAsVirtualRegisters();
for (unsigned i = 0; i < usedLocals.size(); ++i) {
if (!usedLocals.get(i)) {
allocation[i] = UINT_MAX;
continue;
}
allocation[i] = m_graph.m_nextMachineLocal++;
}
for (unsigned i = m_graph.m_variableAccessData.size(); i--;) {
VariableAccessData* variable = &m_graph.m_variableAccessData[i];
if (!variable->isRoot())
continue;
if (variable->local().isArgument()) {
variable->machineLocal() = variable->local();
continue;
}
size_t local = variable->local().toLocal();
if (local >= allocation.size())
continue;
if (allocation[local] == UINT_MAX)
continue;
variable->machineLocal() = assign(allocation, variable->local());
}
for (StackAccessData* data : m_graph.m_stackAccessData) {
if (!data->local.isLocal()) {
data->machineLocal = data->local;
continue;
}
if (static_cast<size_t>(data->local.toLocal()) >= allocation.size())
continue;
if (allocation[data->local.toLocal()] == UINT_MAX)
continue;
data->machineLocal = assign(allocation, data->local);
}
if (!m_graph.needsScopeRegister())
codeBlock()->setScopeRegister(VirtualRegister());
else
codeBlock()->setScopeRegister(assign(allocation, codeBlock()->scopeRegister()));
for (unsigned i = m_graph.m_inlineVariableData.size(); i--;) {
InlineVariableData data = m_graph.m_inlineVariableData[i];
InlineCallFrame* inlineCallFrame = data.inlineCallFrame;
if (inlineCallFrame->isVarargs()) {
inlineCallFrame->argumentCountRegister = assign(
allocation, VirtualRegister(inlineCallFrame->stackOffset + CallFrameSlot::argumentCount));
}
for (unsigned argument = inlineCallFrame->argumentsWithFixup.size(); argument--;) {
ArgumentPosition& position = m_graph.m_argumentPositions[
data.argumentPositionStart + argument];
VariableAccessData* variable = position.someVariable();
ValueSource source;
if (!variable)
source = ValueSource(SourceIsDead);
else {
source = ValueSource::forFlushFormat(
variable->machineLocal(), variable->flushFormat());
}
inlineCallFrame->argumentsWithFixup[argument] = source.valueRecovery();
}
RELEASE_ASSERT(inlineCallFrame->isClosureCall == !!data.calleeVariable);
if (inlineCallFrame->isClosureCall) {
VariableAccessData* variable = data.calleeVariable->find();
ValueSource source = ValueSource::forFlushFormat(
variable->machineLocal(),
variable->flushFormat());
inlineCallFrame->calleeRecovery = source.valueRecovery();
} else
RELEASE_ASSERT(inlineCallFrame->calleeRecovery.isConstant());
}
// Fix Varargs' variable references.
if (hasNodesThatNeedFixup) {
for (BlockIndex blockIndex = m_graph.numBlocks(); blockIndex--;) {
BasicBlock* block = m_graph.block(blockIndex);
if (!block)
continue;
for (unsigned nodeIndex = block->size(); nodeIndex--;) {
Node* node = block->at(nodeIndex);
switch (node->op()) {
case LoadVarargs:
case ForwardVarargs: {
LoadVarargsData* data = node->loadVarargsData();
data->machineCount = assign(allocation, data->count);
data->machineStart = assign(allocation, data->start);
break;
}
default:
break;
}
}
}
}
return true;
}
private:
VirtualRegister assign(const Vector<unsigned>& allocation, VirtualRegister src)
{
VirtualRegister result = src;
if (result.isLocal()) {
unsigned myAllocation = allocation[result.toLocal()];
if (myAllocation == UINT_MAX)
result = VirtualRegister();
else
result = virtualRegisterForLocal(myAllocation);
}
return result;
}
};
bool performStackLayout(Graph& graph)
{
return runPhase<StackLayoutPhase>(graph);
}
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)