[Turbofan] Add the concept of aliasing to RegisterConfiguration.

src/compiler/move-optimizer.cc

Index: src/compiler/move-optimizer.cc
diff --git a/src/compiler/move-optimizer.cc b/src/compiler/move-optimizer.cc
index 715eb414bbff8288a37b38f9850b67a224735e2a..5e163a76c1beb29816fbdb6e33e9b281e50d830b 100644
--- a/src/compiler/move-optimizer.cc
+++ b/src/compiler/move-optimizer.cc
@@ -28,20 +28,34 @@ typedef ZoneMap<MoveKey, unsigned, MoveKeyCompare> MoveMap;
 typedef ZoneSet<InstructionOperand, CompareOperandModuloType> OperandSet;
 
 bool Blocks(const OperandSet& set, const InstructionOperand& operand) {
-  if (!operand.IsFPRegister()) return set.find(operand) != set.end();
+  if (set.find(operand) != set.end()) return true;
+  // Only FP registers alias.
+  if (!operand.IsFPRegister()) return false;
 
   const LocationOperand& loc = LocationOperand::cast(operand);
-  if (loc.representation() == MachineRepresentation::kFloat64) {
-    return set.find(operand) != set.end() ||
-           set.find(LocationOperand(loc.kind(), loc.location_kind(),
-                                    MachineRepresentation::kFloat32,
-                                    loc.register_code())) != set.end();
-  }
-  DCHECK_EQ(MachineRepresentation::kFloat32, loc.representation());
-  return set.find(operand) != set.end() ||
-         set.find(LocationOperand(loc.kind(), loc.location_kind(),
-                                  MachineRepresentation::kFloat64,
-                                  loc.register_code())) != set.end();
+  MachineRepresentation rep = loc.representation();
+  MachineRepresentation other_fp_rep = rep == MachineRepresentation::kFloat64
+                                           ? MachineRepresentation::kFloat32
+                                           : MachineRepresentation::kFloat64;
+  const RegisterConfiguration* config =
+      RegisterConfiguration::ArchDefault(RegisterConfiguration::TURBOFAN);
+  if (config->fp_aliasing_kind() != RegisterConfiguration::COMBINE) {
+    // Overlap aliasing case.
+    return set.find(LocationOperand(loc.kind(), loc.location_kind(),
+                                    other_fp_rep, loc.register_code())) !=
+           set.end();
+  }
+  // Combine aliasing case.
+  int alias_base_index;
+  int aliases = config->GetAliases(rep, loc.register_code(), other_fp_rep,
+                                   &alias_base_index);
+  while (aliases--) {
+    int aliased_reg = alias_base_index + aliases;
+    if (set.find(LocationOperand(loc.kind(), loc.location_kind(), other_fp_rep,
+                                 aliased_reg)) != set.end())
+      return true;
+  }
+  return false;
 }
 
 int FindFirstNonEmptySlot(const Instruction* instr) {