Change the algorithm and generated code for parallel moves on IA32.

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 7f9b5bd2cd95e9e211d6bc405fcd8ca985de5c1c..d29d0c836737a65771fd71bb773b37b0961dcf26 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -58,157 +58,6 @@ class SafepointGenerator : public PostCallGenerator {
 };
 
 
-class LGapNode: public ZoneObject {
- public:
-  explicit LGapNode(LOperand* operand)
-      : operand_(operand), resolved_(false), visited_id_(-1) { }
-
-  LOperand* operand() const { return operand_; }
-  bool IsResolved() const { return !IsAssigned() || resolved_; }
-  void MarkResolved() {
-    ASSERT(!IsResolved());
-    resolved_ = true;
-  }
-  int visited_id() const { return visited_id_; }
-  void set_visited_id(int id) {
-    ASSERT(id > visited_id_);
-    visited_id_ = id;
-  }
-
-  bool IsAssigned() const { return assigned_from_.is_set(); }
-  LGapNode* assigned_from() const { return assigned_from_.get(); }
-  void set_assigned_from(LGapNode* n) { assigned_from_.set(n); }
-
- private:
-  LOperand* operand_;
-  SetOncePointer<LGapNode> assigned_from_;
-  bool resolved_;
-  int visited_id_;
-};
-
-
-LGapResolver::LGapResolver()
-    : nodes_(32),
-      identified_cycles_(4),
-      result_(16),
-      next_visited_id_(0) {
-}
-
-
-const ZoneList<LMoveOperands>* LGapResolver::Resolve(
-    const ZoneList<LMoveOperands>* moves,
-    LOperand* marker_operand) {
-  nodes_.Rewind(0);
-  identified_cycles_.Rewind(0);
-  result_.Rewind(0);
-  next_visited_id_ = 0;
-
-  for (int i = 0; i < moves->length(); ++i) {
-    LMoveOperands move = moves->at(i);
-    if (!move.IsRedundant()) RegisterMove(move);
-  }
-
-  for (int i = 0; i < identified_cycles_.length(); ++i) {
-    ResolveCycle(identified_cycles_[i], marker_operand);
-  }
-
-  int unresolved_nodes;
-  do {
-    unresolved_nodes = 0;
-    for (int j = 0; j < nodes_.length(); j++) {
-      LGapNode* node = nodes_[j];
-      if (!node->IsResolved() && node->assigned_from()->IsResolved()) {
-        AddResultMove(node->assigned_from(), node);
-        node->MarkResolved();
-      }
-      if (!node->IsResolved()) ++unresolved_nodes;
-    }
-  } while (unresolved_nodes > 0);
-  return &result_;
-}
-
-
-void LGapResolver::AddResultMove(LGapNode* from, LGapNode* to) {
-  AddResultMove(from->operand(), to->operand());
-}
-
-
-void LGapResolver::AddResultMove(LOperand* from, LOperand* to) {
-  result_.Add(LMoveOperands(from, to));
-}
-
-
-void LGapResolver::ResolveCycle(LGapNode* start, LOperand* marker_operand) {
-  ZoneList<LOperand*> cycle_operands(8);
-  cycle_operands.Add(marker_operand);
-  LGapNode* cur = start;
-  do {
-    cur->MarkResolved();
-    cycle_operands.Add(cur->operand());
-    cur = cur->assigned_from();
-  } while (cur != start);
-  cycle_operands.Add(marker_operand);
-
-  for (int i = cycle_operands.length() - 1; i > 0; --i) {
-    LOperand* from = cycle_operands[i];
-    LOperand* to = cycle_operands[i - 1];
-    AddResultMove(from, to);
-  }
-}
-
-
-bool LGapResolver::CanReach(LGapNode* a, LGapNode* b, int visited_id) {
-  ASSERT(a != b);
-  LGapNode* cur = a;
-  while (cur != b && cur->visited_id() != visited_id && cur->IsAssigned()) {
-    cur->set_visited_id(visited_id);
-    cur = cur->assigned_from();
-  }
-
-  return cur == b;
-}
-
-
-bool LGapResolver::CanReach(LGapNode* a, LGapNode* b) {
-  ASSERT(a != b);
-  return CanReach(a, b, next_visited_id_++);
-}
-
-
-void LGapResolver::RegisterMove(LMoveOperands move) {
-  if (move.from()->IsConstantOperand()) {
-    // Constant moves should be last in the machine code. Therefore add them
-    // first to the result set.
-    AddResultMove(move.from(), move.to());
-  } else {
-    LGapNode* from = LookupNode(move.from());
-    LGapNode* to = LookupNode(move.to());
-    if (to->IsAssigned() && to->assigned_from() == from) {
-      move.Eliminate();
-      return;
-    }
-    ASSERT(!to->IsAssigned());
-    if (CanReach(from, to)) {
-      // This introduces a cycle. Save.
-      identified_cycles_.Add(from);
-    }
-    to->set_assigned_from(from);
-  }
-}
-
-
-LGapNode* LGapResolver::LookupNode(LOperand* operand) {
-  for (int i = 0; i < nodes_.length(); ++i) {
-    if (nodes_[i]->operand()->Equals(operand)) return nodes_[i];
-  }
-
-  // No node found => create a new one.
-  LGapNode* result = new LGapNode(operand);
-  nodes_.Add(result);
-  return result;
-}
-
-
 #define __ masm()->
 
 bool LCodeGen::GenerateCode() {
@@ -427,6 +276,14 @@ Operand LCodeGen::ToOperand(LOperand* op) const {
 }
 
 
+Operand LCodeGen::HighOperand(LOperand* op) {
+  ASSERT(op->IsDoubleStackSlot());
+  int index = op->index();
+  int offset = (index >= 0) ? index + 3 : index - 1;
+  return Operand(ebp, -offset * kPointerSize);
+}
+
+
 void LCodeGen::WriteTranslation(LEnvironment* environment,
                                 Translation* translation) {
   if (environment == NULL) return;
@@ -762,66 +619,7 @@ void LCodeGen::DoLabel(LLabel* label) {
 
 
 void LCodeGen::DoParallelMove(LParallelMove* move) {
-  // xmm0 must always be a scratch register.
-  XMMRegister xmm_scratch = xmm0;
-  LUnallocated marker_operand(LUnallocated::NONE);
-
-  Register cpu_scratch = esi;
-  bool destroys_cpu_scratch = false;
-
-  const ZoneList<LMoveOperands>* moves =
-      resolver_.Resolve(move->move_operands(), &marker_operand);
-  for (int i = moves->length() - 1; i >= 0; --i) {
-    LMoveOperands move = moves->at(i);
-    LOperand* from = move.from();
-    LOperand* to = move.to();
-    ASSERT(!from->IsDoubleRegister() ||
-           !ToDoubleRegister(from).is(xmm_scratch));
-    ASSERT(!to->IsDoubleRegister() || !ToDoubleRegister(to).is(xmm_scratch));
-    ASSERT(!from->IsRegister() || !ToRegister(from).is(cpu_scratch));
-    ASSERT(!to->IsRegister() || !ToRegister(to).is(cpu_scratch));
-    if (from->IsConstantOperand()) {
-      __ mov(ToOperand(to), ToImmediate(from));
-    } else if (from == &marker_operand) {
-      if (to->IsRegister() || to->IsStackSlot()) {
-        __ mov(ToOperand(to), cpu_scratch);
-        ASSERT(destroys_cpu_scratch);
-      } else {
-        ASSERT(to->IsDoubleRegister() || to->IsDoubleStackSlot());
-        __ movdbl(ToOperand(to), xmm_scratch);
-      }
-    } else if (to == &marker_operand) {
-      if (from->IsRegister() || from->IsStackSlot()) {
-        __ mov(cpu_scratch, ToOperand(from));
-        destroys_cpu_scratch = true;
-      } else {
-        ASSERT(from->IsDoubleRegister() || from->IsDoubleStackSlot());
-        __ movdbl(xmm_scratch, ToOperand(from));
-      }
-    } else if (from->IsRegister()) {
-      __ mov(ToOperand(to), ToRegister(from));
-    } else if (to->IsRegister()) {
-      __ mov(ToRegister(to), ToOperand(from));
-    } else if (from->IsStackSlot()) {
-      ASSERT(to->IsStackSlot());
-      __ push(eax);
-      __ mov(eax, ToOperand(from));
-      __ mov(ToOperand(to), eax);
-      __ pop(eax);
-    } else if (from->IsDoubleRegister()) {
-      __ movdbl(ToOperand(to), ToDoubleRegister(from));
-    } else if (to->IsDoubleRegister()) {
-      __ movdbl(ToDoubleRegister(to), ToOperand(from));
-    } else {
-      ASSERT(to->IsDoubleStackSlot() && from->IsDoubleStackSlot());
-      __ movdbl(xmm_scratch, ToOperand(from));
-      __ movdbl(ToOperand(to), xmm_scratch);
-    }
-  }
-
-  if (destroys_cpu_scratch) {
-    __ mov(cpu_scratch, Operand(ebp, -kPointerSize));
-  }
+  resolver_.Resolve(move);
 }