src/compiler/move-optimizer.cc - platform/external/v8 - Git at Google

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "src/compiler/move-optimizer.h"

 namespace v8 {
 namespace internal {
 namespace compiler {

 namespace {

 typedef std::pair<InstructionOperand, InstructionOperand> MoveKey;

 struct MoveKeyCompare {
   bool operator()(const MoveKey& a, const MoveKey& b) const {
     if (a.first.EqualsCanonicalized(b.first)) {
       return a.second.CompareCanonicalized(b.second);
     }
     return a.first.CompareCanonicalized(b.first);
   }
 };

 struct OperandCompare {
   bool operator()(const InstructionOperand& a,
                   const InstructionOperand& b) const {
     return a.CompareCanonicalized(b);
   }
 };

 typedef ZoneMap<MoveKey, unsigned, MoveKeyCompare> MoveMap;
 typedef ZoneSet<InstructionOperand, CompareOperandModuloType> OperandSet;


 bool GapsCanMoveOver(Instruction* instr, Zone* zone) {
   if (instr->IsNop()) return true;
   if (instr->ClobbersTemps() || instr->ClobbersRegisters() ||
       instr->ClobbersDoubleRegisters()) {
     return false;
   }
   if (instr->arch_opcode() != ArchOpcode::kArchNop) return false;

   ZoneSet<InstructionOperand, OperandCompare> operands(zone);
   for (size_t i = 0; i < instr->InputCount(); ++i) {
     operands.insert(*instr->InputAt(i));
   }
   for (size_t i = 0; i < instr->OutputCount(); ++i) {
     operands.insert(*instr->OutputAt(i));
   }
   for (size_t i = 0; i < instr->TempCount(); ++i) {
     operands.insert(*instr->TempAt(i));
   }
   for (int i = Instruction::GapPosition::FIRST_GAP_POSITION;
        i <= Instruction::GapPosition::LAST_GAP_POSITION; ++i) {
     ParallelMove* moves = instr->parallel_moves()[i];
     if (moves == nullptr) continue;
     for (MoveOperands* move : *moves) {
       if (operands.count(move->source()) > 0 ||
           operands.count(move->destination()) > 0) {
         return false;
       }
     }
   }
   return true;
 }


 int FindFirstNonEmptySlot(const Instruction* instr) {
   int i = Instruction::FIRST_GAP_POSITION;
   for (; i <= Instruction::LAST_GAP_POSITION; i++) {
     ParallelMove* moves = instr->parallel_moves()[i];
     if (moves == nullptr) continue;
     for (MoveOperands* move : *moves) {
       if (!move->IsRedundant()) return i;
       move->Eliminate();
     }
     moves->clear();  // Clear this redundant move.
   }
   return i;
 }

 }  // namespace


 MoveOptimizer::MoveOptimizer(Zone* local_zone, InstructionSequence* code)
     : local_zone_(local_zone),
       code_(code),
       to_finalize_(local_zone),
       local_vector_(local_zone) {}


 void MoveOptimizer::Run() {
   for (InstructionBlock* block : code()->instruction_blocks()) {
     CompressBlock(block);
   }
   for (InstructionBlock* block : code()->instruction_blocks()) {
     if (block->PredecessorCount() <= 1) continue;
     if (!block->IsDeferred()) {
       bool has_only_deferred = true;
       for (RpoNumber& pred_id : block->predecessors()) {
         if (!code()->InstructionBlockAt(pred_id)->IsDeferred()) {
           has_only_deferred = false;
           break;
         }
       }
       // This would pull down common moves. If the moves occur in deferred
       // blocks, and the closest common successor is not deferred, we lose the
       // optimization of just spilling/filling in deferred blocks, when the
       // current block is not deferred.
       if (has_only_deferred) continue;
     }
     OptimizeMerge(block);
   }
   for (Instruction* gap : to_finalize_) {
     FinalizeMoves(gap);
   }
 }


 void MoveOptimizer::CompressMoves(ParallelMove* left, ParallelMove* right) {
   if (right == nullptr) return;

   MoveOpVector& eliminated = local_vector();
   DCHECK(eliminated.empty());

   if (!left->empty()) {
     // Modify the right moves in place and collect moves that will be killed by
     // merging the two gaps.
     for (MoveOperands* move : *right) {
       if (move->IsRedundant()) continue;
       MoveOperands* to_eliminate = left->PrepareInsertAfter(move);
       if (to_eliminate != nullptr) eliminated.push_back(to_eliminate);
     }
     // Eliminate dead moves.
     for (MoveOperands* to_eliminate : eliminated) {
       to_eliminate->Eliminate();
     }
     eliminated.clear();
   }
   // Add all possibly modified moves from right side.
   for (MoveOperands* move : *right) {
     if (move->IsRedundant()) continue;
     left->push_back(move);
   }
   // Nuke right.
   right->clear();
   DCHECK(eliminated.empty());
 }


 // Smash all consecutive moves into the left most move slot and accumulate them
 // as much as possible across instructions.
 void MoveOptimizer::CompressBlock(InstructionBlock* block) {
   Instruction* prev_instr = nullptr;
   for (int index = block->code_start(); index < block->code_end(); ++index) {
     Instruction* instr = code()->instructions()[index];
     int i = FindFirstNonEmptySlot(instr);
     bool has_moves = i <= Instruction::LAST_GAP_POSITION;

     if (i == Instruction::LAST_GAP_POSITION) {
       std::swap(instr->parallel_moves()[Instruction::FIRST_GAP_POSITION],
                 instr->parallel_moves()[Instruction::LAST_GAP_POSITION]);
     } else if (i == Instruction::FIRST_GAP_POSITION) {
       CompressMoves(instr->parallel_moves()[Instruction::FIRST_GAP_POSITION],
                     instr->parallel_moves()[Instruction::LAST_GAP_POSITION]);
     }
     // We either have no moves, or, after swapping or compressing, we have
     // all the moves in the first gap position, and none in the second/end gap
     // position.
     ParallelMove* first =
         instr->parallel_moves()[Instruction::FIRST_GAP_POSITION];
     ParallelMove* last =
         instr->parallel_moves()[Instruction::LAST_GAP_POSITION];
     USE(last);

     DCHECK(!has_moves ||
            (first != nullptr && (last == nullptr || last->empty())));

     if (prev_instr != nullptr) {
       if (has_moves) {
         // Smash first into prev_instr, killing left.
         ParallelMove* pred_moves = prev_instr->parallel_moves()[0];
         CompressMoves(pred_moves, first);
       }
       // Slide prev_instr down so we always know where to look for it.
       std::swap(prev_instr->parallel_moves()[0], instr->parallel_moves()[0]);
     }

     prev_instr = instr->parallel_moves()[0] == nullptr ? nullptr : instr;
     if (GapsCanMoveOver(instr, local_zone())) continue;
     if (prev_instr != nullptr) {
       to_finalize_.push_back(prev_instr);
       prev_instr = nullptr;
     }
   }
   if (prev_instr != nullptr) {
     to_finalize_.push_back(prev_instr);
   }
 }


 const Instruction* MoveOptimizer::LastInstruction(
     const InstructionBlock* block) const {
   return code()->instructions()[block->last_instruction_index()];
 }


 void MoveOptimizer::OptimizeMerge(InstructionBlock* block) {
   DCHECK(block->PredecessorCount() > 1);
   // Ensure that the last instruction in all incoming blocks don't contain
   // things that would prevent moving gap moves across them.
   for (RpoNumber& pred_index : block->predecessors()) {
     const InstructionBlock* pred = code()->InstructionBlockAt(pred_index);
     const Instruction* last_instr =
         code()->instructions()[pred->last_instruction_index()];
     if (last_instr->IsCall()) return;
     if (last_instr->TempCount() != 0) return;
     if (last_instr->OutputCount() != 0) return;
     for (size_t i = 0; i < last_instr->InputCount(); ++i) {
       const InstructionOperand* op = last_instr->InputAt(i);
       if (!op->IsConstant() && !op->IsImmediate()) return;
     }
   }
   // TODO(dcarney): pass a ZonePool down for this?
   MoveMap move_map(local_zone());
   size_t correct_counts = 0;
   // Accumulate set of shared moves.
   for (RpoNumber& pred_index : block->predecessors()) {
     const InstructionBlock* pred = code()->InstructionBlockAt(pred_index);
     const Instruction* instr = LastInstruction(pred);
     if (instr->parallel_moves()[0] == nullptr ||
         instr->parallel_moves()[0]->empty()) {
       return;
     }
     for (const MoveOperands* move : *instr->parallel_moves()[0]) {
       if (move->IsRedundant()) continue;
       InstructionOperand src = move->source();
       InstructionOperand dst = move->destination();
       MoveKey key = {src, dst};
       auto res = move_map.insert(std::make_pair(key, 1));
       if (!res.second) {
         res.first->second++;
         if (res.first->second == block->PredecessorCount()) {
           correct_counts++;
         }
       }
     }
   }
   if (move_map.empty() || correct_counts != move_map.size()) return;
   // Find insertion point.
   Instruction* instr = nullptr;
   for (int i = block->first_instruction_index();
        i <= block->last_instruction_index(); ++i) {
     instr = code()->instructions()[i];
     if (!GapsCanMoveOver(instr, local_zone()) || !instr->AreMovesRedundant())
       break;
   }
   DCHECK_NOT_NULL(instr);
   bool gap_initialized = true;
   if (instr->parallel_moves()[0] == nullptr ||
       instr->parallel_moves()[0]->empty()) {
     to_finalize_.push_back(instr);
   } else {
     // Will compress after insertion.
     gap_initialized = false;
     std::swap(instr->parallel_moves()[0], instr->parallel_moves()[1]);
   }
   ParallelMove* moves = instr->GetOrCreateParallelMove(
       static_cast<Instruction::GapPosition>(0), code_zone());
   // Delete relevant entries in predecessors and move everything to block.
   bool first_iteration = true;
   for (RpoNumber& pred_index : block->predecessors()) {
     const InstructionBlock* pred = code()->InstructionBlockAt(pred_index);
     for (MoveOperands* move : *LastInstruction(pred)->parallel_moves()[0]) {
       if (move->IsRedundant()) continue;
       MoveKey key = {move->source(), move->destination()};
       auto it = move_map.find(key);
       USE(it);
       DCHECK(it != move_map.end());
       if (first_iteration) {
         moves->AddMove(move->source(), move->destination());
       }
       move->Eliminate();
     }
     first_iteration = false;
   }
   // Compress.
   if (!gap_initialized) {
     CompressMoves(instr->parallel_moves()[0], instr->parallel_moves()[1]);
   }
 }


 namespace {

 bool IsSlot(const InstructionOperand& op) {
   return op.IsStackSlot() || op.IsDoubleStackSlot();
 }


 bool LoadCompare(const MoveOperands* a, const MoveOperands* b) {
   if (!a->source().EqualsCanonicalized(b->source())) {
     return a->source().CompareCanonicalized(b->source());
   }
   if (IsSlot(a->destination()) && !IsSlot(b->destination())) return false;
   if (!IsSlot(a->destination()) && IsSlot(b->destination())) return true;
   return a->destination().CompareCanonicalized(b->destination());
 }

 }  // namespace


 // Split multiple loads of the same constant or stack slot off into the second
 // slot and keep remaining moves in the first slot.
 void MoveOptimizer::FinalizeMoves(Instruction* instr) {
   MoveOpVector& loads = local_vector();
   DCHECK(loads.empty());

   // Find all the loads.
   for (MoveOperands* move : *instr->parallel_moves()[0]) {
     if (move->IsRedundant()) continue;
     if (move->source().IsConstant() || IsSlot(move->source())) {
       loads.push_back(move);
     }
   }
   if (loads.empty()) return;
   // Group the loads by source, moving the preferred destination to the
   // beginning of the group.
   std::sort(loads.begin(), loads.end(), LoadCompare);
   MoveOperands* group_begin = nullptr;
   for (MoveOperands* load : loads) {
     // New group.
     if (group_begin == nullptr ||
         !load->source().EqualsCanonicalized(group_begin->source())) {
       group_begin = load;
       continue;
     }
     // Nothing to be gained from splitting here.
     if (IsSlot(group_begin->destination())) continue;
     // Insert new move into slot 1.
     ParallelMove* slot_1 = instr->GetOrCreateParallelMove(
         static_cast<Instruction::GapPosition>(1), code_zone());
     slot_1->AddMove(group_begin->destination(), load->destination());
     load->Eliminate();
   }
   loads.clear();
 }

 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
	// Copyright 2014 the V8 project authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "src/compiler/move-optimizer.h"

	namespace v8 {
	namespace internal {
	namespace compiler {

	namespace {

	typedef std::pair<InstructionOperand, InstructionOperand> MoveKey;

	struct MoveKeyCompare {
	bool operator()(const MoveKey& a, const MoveKey& b) const {
	if (a.first.EqualsCanonicalized(b.first)) {
	return a.second.CompareCanonicalized(b.second);
	}
	return a.first.CompareCanonicalized(b.first);
	}
	};

	struct OperandCompare {
	bool operator()(const InstructionOperand& a,
	const InstructionOperand& b) const {
	return a.CompareCanonicalized(b);
	}
	};

	typedef ZoneMap<MoveKey, unsigned, MoveKeyCompare> MoveMap;
	typedef ZoneSet<InstructionOperand, CompareOperandModuloType> OperandSet;


	bool GapsCanMoveOver(Instruction* instr, Zone* zone) {
	if (instr->IsNop()) return true;
	if (instr->ClobbersTemps() \|\| instr->ClobbersRegisters() \|\|
	instr->ClobbersDoubleRegisters()) {
	return false;
	}
	if (instr->arch_opcode() != ArchOpcode::kArchNop) return false;

	ZoneSet<InstructionOperand, OperandCompare> operands(zone);
	for (size_t i = 0; i < instr->InputCount(); ++i) {
	operands.insert(*instr->InputAt(i));
	}
	for (size_t i = 0; i < instr->OutputCount(); ++i) {
	operands.insert(*instr->OutputAt(i));
	}
	for (size_t i = 0; i < instr->TempCount(); ++i) {
	operands.insert(*instr->TempAt(i));
	}
	for (int i = Instruction::GapPosition::FIRST_GAP_POSITION;
	i <= Instruction::GapPosition::LAST_GAP_POSITION; ++i) {
	ParallelMove* moves = instr->parallel_moves()[i];
	if (moves == nullptr) continue;
	for (MoveOperands* move : *moves) {
	if (operands.count(move->source()) > 0 \|\|
	operands.count(move->destination()) > 0) {
	return false;
	}
	}
	}
	return true;
	}


	int FindFirstNonEmptySlot(const Instruction* instr) {
	int i = Instruction::FIRST_GAP_POSITION;
	for (; i <= Instruction::LAST_GAP_POSITION; i++) {
	ParallelMove* moves = instr->parallel_moves()[i];
	if (moves == nullptr) continue;
	for (MoveOperands* move : *moves) {
	if (!move->IsRedundant()) return i;
	move->Eliminate();
	}
	moves->clear(); // Clear this redundant move.
	}
	return i;
	}

	} // namespace


	MoveOptimizer::MoveOptimizer(Zone* local_zone, InstructionSequence* code)
	: local_zone_(local_zone),
	code_(code),
	to_finalize_(local_zone),
	local_vector_(local_zone) {}


	void MoveOptimizer::Run() {
	for (InstructionBlock* block : code()->instruction_blocks()) {
	CompressBlock(block);
	}
	for (InstructionBlock* block : code()->instruction_blocks()) {
	if (block->PredecessorCount() <= 1) continue;
	if (!block->IsDeferred()) {
	bool has_only_deferred = true;
	for (RpoNumber& pred_id : block->predecessors()) {
	if (!code()->InstructionBlockAt(pred_id)->IsDeferred()) {
	has_only_deferred = false;
	break;
	}
	}
	// This would pull down common moves. If the moves occur in deferred
	// blocks, and the closest common successor is not deferred, we lose the
	// optimization of just spilling/filling in deferred blocks, when the
	// current block is not deferred.
	if (has_only_deferred) continue;
	}
	OptimizeMerge(block);
	}
	for (Instruction* gap : to_finalize_) {
	FinalizeMoves(gap);
	}
	}


	void MoveOptimizer::CompressMoves(ParallelMove* left, ParallelMove* right) {
	if (right == nullptr) return;

	MoveOpVector& eliminated = local_vector();
	DCHECK(eliminated.empty());

	if (!left->empty()) {
	// Modify the right moves in place and collect moves that will be killed by
	// merging the two gaps.
	for (MoveOperands* move : *right) {
	if (move->IsRedundant()) continue;
	MoveOperands* to_eliminate = left->PrepareInsertAfter(move);
	if (to_eliminate != nullptr) eliminated.push_back(to_eliminate);
	}
	// Eliminate dead moves.
	for (MoveOperands* to_eliminate : eliminated) {
	to_eliminate->Eliminate();
	}
	eliminated.clear();
	}
	// Add all possibly modified moves from right side.
	for (MoveOperands* move : *right) {
	if (move->IsRedundant()) continue;
	left->push_back(move);
	}
	// Nuke right.
	right->clear();
	DCHECK(eliminated.empty());
	}


	// Smash all consecutive moves into the left most move slot and accumulate them
	// as much as possible across instructions.
	void MoveOptimizer::CompressBlock(InstructionBlock* block) {
	Instruction* prev_instr = nullptr;
	for (int index = block->code_start(); index < block->code_end(); ++index) {
	Instruction* instr = code()->instructions()[index];
	int i = FindFirstNonEmptySlot(instr);
	bool has_moves = i <= Instruction::LAST_GAP_POSITION;

	if (i == Instruction::LAST_GAP_POSITION) {
	std::swap(instr->parallel_moves()[Instruction::FIRST_GAP_POSITION],
	instr->parallel_moves()[Instruction::LAST_GAP_POSITION]);
	} else if (i == Instruction::FIRST_GAP_POSITION) {
	CompressMoves(instr->parallel_moves()[Instruction::FIRST_GAP_POSITION],
	instr->parallel_moves()[Instruction::LAST_GAP_POSITION]);
	}
	// We either have no moves, or, after swapping or compressing, we have
	// all the moves in the first gap position, and none in the second/end gap
	// position.
	ParallelMove* first =
	instr->parallel_moves()[Instruction::FIRST_GAP_POSITION];
	ParallelMove* last =
	instr->parallel_moves()[Instruction::LAST_GAP_POSITION];
	USE(last);

	DCHECK(!has_moves \|\|
	(first != nullptr && (last == nullptr \|\| last->empty())));

	if (prev_instr != nullptr) {
	if (has_moves) {
	// Smash first into prev_instr, killing left.
	ParallelMove* pred_moves = prev_instr->parallel_moves()[0];
	CompressMoves(pred_moves, first);
	}
	// Slide prev_instr down so we always know where to look for it.
	std::swap(prev_instr->parallel_moves()[0], instr->parallel_moves()[0]);
	}

	prev_instr = instr->parallel_moves()[0] == nullptr ? nullptr : instr;
	if (GapsCanMoveOver(instr, local_zone())) continue;
	if (prev_instr != nullptr) {
	to_finalize_.push_back(prev_instr);
	prev_instr = nullptr;
	}
	}
	if (prev_instr != nullptr) {
	to_finalize_.push_back(prev_instr);
	}
	}


	const Instruction* MoveOptimizer::LastInstruction(
	const InstructionBlock* block) const {
	return code()->instructions()[block->last_instruction_index()];
	}


	void MoveOptimizer::OptimizeMerge(InstructionBlock* block) {
	DCHECK(block->PredecessorCount() > 1);
	// Ensure that the last instruction in all incoming blocks don't contain
	// things that would prevent moving gap moves across them.
	for (RpoNumber& pred_index : block->predecessors()) {
	const InstructionBlock* pred = code()->InstructionBlockAt(pred_index);
	const Instruction* last_instr =
	code()->instructions()[pred->last_instruction_index()];
	if (last_instr->IsCall()) return;
	if (last_instr->TempCount() != 0) return;
	if (last_instr->OutputCount() != 0) return;
	for (size_t i = 0; i < last_instr->InputCount(); ++i) {
	const InstructionOperand* op = last_instr->InputAt(i);
	if (!op->IsConstant() && !op->IsImmediate()) return;
	}
	}
	// TODO(dcarney): pass a ZonePool down for this?
	MoveMap move_map(local_zone());
	size_t correct_counts = 0;
	// Accumulate set of shared moves.
	for (RpoNumber& pred_index : block->predecessors()) {
	const InstructionBlock* pred = code()->InstructionBlockAt(pred_index);
	const Instruction* instr = LastInstruction(pred);
	if (instr->parallel_moves()[0] == nullptr \|\|
	instr->parallel_moves()[0]->empty()) {
	return;
	}
	for (const MoveOperands* move : *instr->parallel_moves()[0]) {
	if (move->IsRedundant()) continue;
	InstructionOperand src = move->source();
	InstructionOperand dst = move->destination();
	MoveKey key = {src, dst};
	auto res = move_map.insert(std::make_pair(key, 1));
	if (!res.second) {
	res.first->second++;
	if (res.first->second == block->PredecessorCount()) {
	correct_counts++;
	}
	}
	}
	}
	if (move_map.empty() \|\| correct_counts != move_map.size()) return;
	// Find insertion point.
	Instruction* instr = nullptr;
	for (int i = block->first_instruction_index();
	i <= block->last_instruction_index(); ++i) {
	instr = code()->instructions()[i];
	if (!GapsCanMoveOver(instr, local_zone()) \|\| !instr->AreMovesRedundant())
	break;
	}
	DCHECK_NOT_NULL(instr);
	bool gap_initialized = true;
	if (instr->parallel_moves()[0] == nullptr \|\|
	instr->parallel_moves()[0]->empty()) {
	to_finalize_.push_back(instr);
	} else {
	// Will compress after insertion.
	gap_initialized = false;
	std::swap(instr->parallel_moves()[0], instr->parallel_moves()[1]);
	}
	ParallelMove* moves = instr->GetOrCreateParallelMove(
	static_cast<Instruction::GapPosition>(0), code_zone());
	// Delete relevant entries in predecessors and move everything to block.
	bool first_iteration = true;
	for (RpoNumber& pred_index : block->predecessors()) {
	const InstructionBlock* pred = code()->InstructionBlockAt(pred_index);
	for (MoveOperands* move : *LastInstruction(pred)->parallel_moves()[0]) {
	if (move->IsRedundant()) continue;
	MoveKey key = {move->source(), move->destination()};
	auto it = move_map.find(key);
	USE(it);
	DCHECK(it != move_map.end());
	if (first_iteration) {
	moves->AddMove(move->source(), move->destination());
	}
	move->Eliminate();
	}
	first_iteration = false;
	}
	// Compress.
	if (!gap_initialized) {
	CompressMoves(instr->parallel_moves()[0], instr->parallel_moves()[1]);
	}
	}


	namespace {

	bool IsSlot(const InstructionOperand& op) {
	return op.IsStackSlot() \|\| op.IsDoubleStackSlot();
	}


	bool LoadCompare(const MoveOperands* a, const MoveOperands* b) {
	if (!a->source().EqualsCanonicalized(b->source())) {
	return a->source().CompareCanonicalized(b->source());
	}
	if (IsSlot(a->destination()) && !IsSlot(b->destination())) return false;
	if (!IsSlot(a->destination()) && IsSlot(b->destination())) return true;
	return a->destination().CompareCanonicalized(b->destination());
	}

	} // namespace


	// Split multiple loads of the same constant or stack slot off into the second
	// slot and keep remaining moves in the first slot.
	void MoveOptimizer::FinalizeMoves(Instruction* instr) {
	MoveOpVector& loads = local_vector();
	DCHECK(loads.empty());

	// Find all the loads.
	for (MoveOperands* move : *instr->parallel_moves()[0]) {
	if (move->IsRedundant()) continue;
	if (move->source().IsConstant() \|\| IsSlot(move->source())) {
	loads.push_back(move);
	}
	}
	if (loads.empty()) return;
	// Group the loads by source, moving the preferred destination to the
	// beginning of the group.
	std::sort(loads.begin(), loads.end(), LoadCompare);
	MoveOperands* group_begin = nullptr;
	for (MoveOperands* load : loads) {
	// New group.
	if (group_begin == nullptr \|\|
	!load->source().EqualsCanonicalized(group_begin->source())) {
	group_begin = load;
	continue;
	}
	// Nothing to be gained from splitting here.
	if (IsSlot(group_begin->destination())) continue;
	// Insert new move into slot 1.
	ParallelMove* slot_1 = instr->GetOrCreateParallelMove(
	static_cast<Instruction::GapPosition>(1), code_zone());
	slot_1->AddMove(group_begin->destination(), load->destination());
	load->Eliminate();
	}
	loads.clear();
	}

	} // namespace compiler
	} // namespace internal
	} // namespace v8