[turbofan] cleanup ParallelMove

src/compiler/gap-resolver.cc

 // 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/gap-resolver.h"
 
 #include <algorithm>
 #include <functional>
 #include <set>
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
-typedef ZoneList<MoveOperands>::iterator op_iterator;
+namespace {
 
-#ifdef ENABLE_SLOW_DCHECKS
-struct InstructionOperandComparator {
-  bool operator()(const InstructionOperand* x,
-                  const InstructionOperand* y) const {
-    return *x < *y;
-  }
-};
-#endif
-
-// No operand should be the destination for more than one move.
-static void VerifyMovesAreInjective(ZoneList<MoveOperands>* moves) {
-#ifdef ENABLE_SLOW_DCHECKS
-  std::set<InstructionOperand*, InstructionOperandComparator> seen;
-  for (op_iterator i = moves->begin(); i != moves->end(); ++i) {
-    SLOW_DCHECK(seen.find(i->destination()) == seen.end());
-    seen.insert(i->destination());
-  }
-#endif
+inline bool Blocks(MoveOperands* move, InstructionOperand destination) {
+  return move->Blocks(destination);
 }
 
 
-void GapResolver::Resolve(ParallelMove* parallel_move) const {
-  ZoneList<MoveOperands>* moves = parallel_move->move_operands();
-  // TODO(svenpanne) Use the member version of remove_if when we use real lists.
-  op_iterator end =
-      std::remove_if(moves->begin(), moves->end(),
-                     std::mem_fun_ref(&MoveOperands::IsRedundant));
-  moves->Rewind(static_cast<int>(end - moves->begin()));
+inline bool IsRedundant(MoveOperands* move) { return move->IsRedundant(); }
 
-  VerifyMovesAreInjective(moves);
+}  // namespace
 
-  for (op_iterator move = moves->begin(); move != moves->end(); ++move) {
-    if (!move->IsEliminated()) PerformMove(moves, &*move);
+
+void GapResolver::Resolve(ParallelMove* moves) const {
+  // Clear redundant moves.
+  auto it =
+      std::remove_if(moves->begin(), moves->end(), std::ptr_fun(IsRedundant));
+  moves->erase(it, moves->end());
+  for (auto move : *moves) {
+    if (!move->IsEliminated()) PerformMove(moves, move);
   }
 }
 
 
-void GapResolver::PerformMove(ZoneList<MoveOperands>* moves,
-                              MoveOperands* move) const {
+void GapResolver::PerformMove(ParallelMove* moves, MoveOperands* move) const {
   // Each call to this function performs a move and deletes it from the move
   // graph.  We first recursively perform any move blocking this one.  We mark a
   // move as "pending" on entry to PerformMove in order to detect cycles in the
   // move graph.  We use operand swaps to resolve cycles, which means that a
   // call to PerformMove could change any source operand in the move graph.
   DCHECK(!move->IsPending());
   DCHECK(!move->IsRedundant());
 
   // Clear this move's destination to indicate a pending move.  The actual
   // destination is saved on the side.
-  DCHECK_NOT_NULL(move->source());  // Or else it will look eliminated.
-  InstructionOperand* destination = move->destination();
-  move->set_destination(NULL);
+  DCHECK(!move->source().IsInvalid());  // Or else it will look eliminated.
+  InstructionOperand destination = move->destination();
+  move->SetPending();
 
   // Perform a depth-first traversal of the move graph to resolve dependencies.
   // Any unperformed, unpending move with a source the same as this one's
   // destination blocks this one so recursively perform all such moves.
-  for (op_iterator other = moves->begin(); other != moves->end(); ++other) {
+  for (auto other : *moves) {
     if (other->Blocks(destination) && !other->IsPending()) {
       // Though PerformMove can change any source operand in the move graph,
       // this call cannot create a blocking move via a swap (this loop does not
       // miss any).  Assume there is a non-blocking move with source A and this
       // move is blocked on source B and there is a swap of A and B.  Then A and
       // B must be involved in the same cycle (or they would not be swapped).
       // Since this move's destination is B and there is only a single incoming
       // edge to an operand, this move must also be involved in the same cycle.
       // In that case, the blocking move will be created but will be "pending"
       // when we return from PerformMove.
       PerformMove(moves, other);
     }
   }
 
   // We are about to resolve this move and don't need it marked as pending, so
   // restore its destination.
   move->set_destination(destination);
 
   // This move's source may have changed due to swaps to resolve cycles and so
   // it may now be the last move in the cycle.  If so remove it.
-  InstructionOperand* source = move->source();
-  if (source->Equals(destination)) {
+  InstructionOperand source = move->source();
+  if (source == destination) {
     move->Eliminate();
     return;
   }
 
   // The move may be blocked on a (at most one) pending move, in which case we
   // have a cycle.  Search for such a blocking move and perform a swap to
   // resolve it.
-  op_iterator blocker = std::find_if(
-      moves->begin(), moves->end(),
-      std::bind2nd(std::mem_fun_ref(&MoveOperands::Blocks), destination));
+  auto blocker = std::find_if(moves->begin(), moves->end(),
+                              std::bind2nd(std::ptr_fun(&Blocks), destination));
   if (blocker == moves->end()) {
     // The easy case: This move is not blocked.
-    assembler_->AssembleMove(source, destination);
+    assembler_->AssembleMove(&source, &destination);
     move->Eliminate();
     return;
   }
 
-  DCHECK(blocker->IsPending());
+  DCHECK((*blocker)->IsPending());
   // Ensure source is a register or both are stack slots, to limit swap cases.
-  if (source->IsStackSlot() || source->IsDoubleStackSlot()) {
+  if (source.IsStackSlot() || source.IsDoubleStackSlot()) {
     std::swap(source, destination);
   }
-  assembler_->AssembleSwap(source, destination);
+  assembler_->AssembleSwap(&source, &destination);
   move->Eliminate();
 
   // Any unperformed (including pending) move with a source of either this
   // move's source or destination needs to have their source changed to
   // reflect the state of affairs after the swap.
-  for (op_iterator other = moves->begin(); other != moves->end(); ++other) {
+  for (auto other : *moves) {
     if (other->Blocks(source)) {
       other->set_source(destination);
     } else if (other->Blocks(destination)) {
       other->set_source(source);
     }
   }
 }
 }
 }
 }  // namespace v8::internal::compiler