[turbofan] Create ExplicitOperands to specify operands without virtual registers

src/compiler/instruction.h

 // 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.
 
 #ifndef V8_COMPILER_INSTRUCTION_H_
 #define V8_COMPILER_INSTRUCTION_H_
 
 #include <deque>
 #include <iosfwd>
 #include <map>
@@ skipping 13 matching lines @@
 namespace compiler {
 
 class Schedule;
 
 class InstructionOperand {
  public:
   static const int kInvalidVirtualRegister = -1;
 
   // TODO(dcarney): recover bit. INVALID can be represented as UNALLOCATED with
   // kInvalidVirtualRegister and some DCHECKS.
-  enum Kind { INVALID, UNALLOCATED, CONSTANT, IMMEDIATE, ALLOCATED };
+  enum Kind { INVALID, UNALLOCATED, CONSTANT, IMMEDIATE, EXPLICIT, ALLOCATED };
 
   InstructionOperand() : InstructionOperand(INVALID) {}
 
   Kind kind() const { return KindField::decode(value_); }
 
 #define INSTRUCTION_OPERAND_PREDICATE(name, type) \
   bool Is##name() const { return kind() == type; }
   INSTRUCTION_OPERAND_PREDICATE(Invalid, INVALID)
+  // UnallocatedOperands are place-holder operands created before register
+  // allocation. They later are assigned registers and become AllocatedOperands.
   INSTRUCTION_OPERAND_PREDICATE(Unallocated, UNALLOCATED)
+  // Constant operands participate in register allocation. They are allocated to
+  // registers but have a special "spilling" behavior. When a ConstantOperand
+  // value must be rematerialized, it is loaded from an immediate constant
+  // rather from an unspilled slot.
   INSTRUCTION_OPERAND_PREDICATE(Constant, CONSTANT)
+  // ImmediateOperands do not participate in register allocation and are only
+  // embedded directly in instructions, e.g. small integers and on some
+  // platforms Objects.
   INSTRUCTION_OPERAND_PREDICATE(Immediate, IMMEDIATE)
+  // ExplicitOperands do not participate in register allocation. They are
+  // created by the instruction selector for direct access to registers and
+  // stack slots, completely bypassing the register allocator. They are never
+  // associated with a virtual register
+  INSTRUCTION_OPERAND_PREDICATE(Explicit, EXPLICIT)
+  // AllocatedOperands are registers or stack slots that are assigned by the
+  // register allocator and are always associated with a virtual register.

[Jarin, 2015/10/26 13:37:02]

Thank you, the descriptions are great!

   INSTRUCTION_OPERAND_PREDICATE(Allocated, ALLOCATED)
 #undef INSTRUCTION_OPERAND_PREDICATE
 
   inline bool IsRegister() const;
   inline bool IsDoubleRegister() const;
   inline bool IsStackSlot() const;
   inline bool IsDoubleStackSlot() const;
 
   template <typename SubKindOperand>
   static SubKindOperand* New(Zone* zone, const SubKindOperand& op) {
     void* buffer = zone->New(sizeof(op));
     return new (buffer) SubKindOperand(op);
   }
 
   static void ReplaceWith(InstructionOperand* dest,
                           const InstructionOperand* src) {
     *dest = *src;
   }
 
   bool Equals(const InstructionOperand& that) const {
     return this->value_ == that.value_;
   }
 
   bool Compare(const InstructionOperand& that) const {
     return this->value_ < that.value_;
   }
 
-  bool EqualsModuloType(const InstructionOperand& that) const {
-    return this->GetValueModuloType() == that.GetValueModuloType();
+  bool EqualsCanonicalized(const InstructionOperand& that) const {
+    return this->GetCanonicalizedValue() == that.GetCanonicalizedValue();
   }
 
-  bool CompareModuloType(const InstructionOperand& that) const {
-    return this->GetValueModuloType() < that.GetValueModuloType();
+  bool CompareCanonicalized(const InstructionOperand& that) const {
+    return this->GetCanonicalizedValue() < that.GetCanonicalizedValue();
   }
 
  protected:
   explicit InstructionOperand(Kind kind) : value_(KindField::encode(kind)) {}
 
-  inline uint64_t GetValueModuloType() const;
+  inline uint64_t GetCanonicalizedValue() const;
 
   class KindField : public BitField64<Kind, 0, 3> {};
 
   uint64_t value_;
 };
 
 
 struct PrintableInstructionOperand {
   const RegisterConfiguration* register_configuration_;
   InstructionOperand op_;
@@ skipping 251 matching lines @@
   }
 
   INSTRUCTION_OPERAND_CASTS(ImmediateOperand, IMMEDIATE);
 
   STATIC_ASSERT(KindField::kSize == 3);
   class TypeField : public BitField64<ImmediateType, 3, 1> {};
   class ValueField : public BitField64<int32_t, 32, 32> {};
 };
 
 
-class AllocatedOperand : public InstructionOperand {
+class LocationOperand : public InstructionOperand {
  public:
-  // TODO(dcarney): machine_type makes this now redundant. Just need to know is
-  // the operand is a slot or a register.
-  enum AllocatedKind {
-    STACK_SLOT,
-    DOUBLE_STACK_SLOT,
-    REGISTER,
-    DOUBLE_REGISTER
-  };
+  enum LocationKind { REGISTER, STACK_SLOT };
 
-  AllocatedOperand(AllocatedKind kind, MachineType machine_type, int index)
-      : InstructionOperand(ALLOCATED) {
-    DCHECK_IMPLIES(kind == REGISTER || kind == DOUBLE_REGISTER, index >= 0);
+  LocationOperand(InstructionOperand::Kind operand_kind,
+                  LocationOperand::LocationKind location_kind,
+                  MachineType machine_type, int index)
+      : InstructionOperand(operand_kind) {
+    DCHECK_IMPLIES(location_kind == REGISTER, index >= 0);
     DCHECK(IsSupportedMachineType(machine_type));
-    value_ |= AllocatedKindField::encode(kind);
+    value_ |= LocationKindField::encode(location_kind);
     value_ |= MachineTypeField::encode(machine_type);
     value_ |= static_cast<int64_t>(index) << IndexField::kShift;
   }
 
   int index() const {
-    DCHECK(STACK_SLOT == allocated_kind() ||
-           DOUBLE_STACK_SLOT == allocated_kind());
+    DCHECK(IsStackSlot() || IsDoubleStackSlot());
     return static_cast<int64_t>(value_) >> IndexField::kShift;
   }
 
   Register GetRegister() const {
-    DCHECK(REGISTER == allocated_kind() || DOUBLE_REGISTER == allocated_kind());
+    DCHECK(IsRegister());
     return Register::from_code(static_cast<int64_t>(value_) >>
                                IndexField::kShift);
   }
 
   DoubleRegister GetDoubleRegister() const {
-    DCHECK(REGISTER == allocated_kind() || DOUBLE_REGISTER == allocated_kind());
+    DCHECK(IsDoubleRegister());
     return DoubleRegister::from_code(static_cast<int64_t>(value_) >>
                                      IndexField::kShift);
   }
 
-  AllocatedKind allocated_kind() const {
-    return AllocatedKindField::decode(value_);
+  LocationKind location_kind() const {
+    return LocationKindField::decode(value_);
   }
 
   MachineType machine_type() const { return MachineTypeField::decode(value_); }
 
-  static AllocatedOperand* New(Zone* zone, AllocatedKind kind,
-                               MachineType machine_type, int index) {
-    return InstructionOperand::New(zone,
-                                   AllocatedOperand(kind, machine_type, index));
-  }
-
   static bool IsSupportedMachineType(MachineType machine_type) {
     if (RepresentationOf(machine_type) != machine_type) return false;
     switch (machine_type) {
       case kRepWord32:
       case kRepWord64:
       case kRepFloat32:
       case kRepFloat64:
       case kRepTagged:
         return true;
       default:
         return false;
     }
   }
 
-  INSTRUCTION_OPERAND_CASTS(AllocatedOperand, ALLOCATED);
+  static LocationOperand* cast(InstructionOperand* op) {
+    DCHECK(ALLOCATED == op->kind() || EXPLICIT == op->kind());
+    return static_cast<LocationOperand*>(op);
+  }
+
+  static const LocationOperand* cast(const InstructionOperand* op) {
+    DCHECK(ALLOCATED == op->kind() || EXPLICIT == op->kind());
+    return static_cast<const LocationOperand*>(op);
+  }
+
+  static LocationOperand cast(const InstructionOperand& op) {
+    DCHECK(ALLOCATED == op.kind() || EXPLICIT == op.kind());
+    return *static_cast<const LocationOperand*>(&op);
+  }
 
   STATIC_ASSERT(KindField::kSize == 3);
-  class AllocatedKindField : public BitField64<AllocatedKind, 3, 2> {};
+  class LocationKindField : public BitField64<LocationKind, 3, 2> {};
   class MachineTypeField : public BitField64<MachineType, 5, 16> {};
   class IndexField : public BitField64<int32_t, 35, 29> {};
 };
 
 
+class ExplicitOperand : public LocationOperand {
+ public:
+  ExplicitOperand(LocationKind kind, MachineType machine_type, int index)
+      : LocationOperand(EXPLICIT, kind, machine_type, index) {}
+
+  static ExplicitOperand* New(Zone* zone, LocationKind kind,
+                              MachineType machine_type, int index) {
+    return InstructionOperand::New(zone,
+                                   ExplicitOperand(kind, machine_type, index));
+  }
+
+  INSTRUCTION_OPERAND_CASTS(ExplicitOperand, EXPLICIT);
+};
+
+
+class AllocatedOperand : public LocationOperand {
+ public:
+  AllocatedOperand(LocationKind kind, MachineType machine_type, int index)
+      : LocationOperand(ALLOCATED, kind, machine_type, index) {}
+
+  static AllocatedOperand* New(Zone* zone, LocationKind kind,
+                               MachineType machine_type, int index) {
+    return InstructionOperand::New(zone,
+                                   AllocatedOperand(kind, machine_type, index));
+  }
+
+  INSTRUCTION_OPERAND_CASTS(AllocatedOperand, ALLOCATED);
+};
+
+
 #undef INSTRUCTION_OPERAND_CASTS
 
 
-#define ALLOCATED_OPERAND_LIST(V)       \
-  V(StackSlot, STACK_SLOT)              \
-  V(DoubleStackSlot, DOUBLE_STACK_SLOT) \
-  V(Register, REGISTER)                 \
-  V(DoubleRegister, DOUBLE_REGISTER)
+bool InstructionOperand::IsRegister() const {
+  return (IsAllocated() || IsExplicit()) &&
+         LocationOperand::cast(this)->location_kind() ==
+             LocationOperand::REGISTER &&
+         !IsFloatingPoint(LocationOperand::cast(this)->machine_type());
+}
 
+bool InstructionOperand::IsDoubleRegister() const {
+  return (IsAllocated() || IsExplicit()) &&
+         LocationOperand::cast(this)->location_kind() ==
+             LocationOperand::REGISTER &&
+         IsFloatingPoint(LocationOperand::cast(this)->machine_type());
+}
 
-#define ALLOCATED_OPERAND_IS(SubKind, kOperandKind)          \
-  bool InstructionOperand::Is##SubKind() const {             \
-    return IsAllocated() &&                                  \
-           AllocatedOperand::cast(this)->allocated_kind() == \
-               AllocatedOperand::kOperandKind;               \
-  }
-ALLOCATED_OPERAND_LIST(ALLOCATED_OPERAND_IS)
-#undef ALLOCATED_OPERAND_IS
+bool InstructionOperand::IsStackSlot() const {
+  return (IsAllocated() || IsExplicit()) &&
+         LocationOperand::cast(this)->location_kind() ==
+             LocationOperand::STACK_SLOT &&
+         !IsFloatingPoint(LocationOperand::cast(this)->machine_type());
+}
 
+bool InstructionOperand::IsDoubleStackSlot() const {
+  return (IsAllocated() || IsExplicit()) &&
+         LocationOperand::cast(this)->location_kind() ==
+             LocationOperand::STACK_SLOT &&
+         IsFloatingPoint(LocationOperand::cast(this)->machine_type());
+}
 
-// TODO(dcarney): these subkinds are now pretty useless, nuke.
-#define ALLOCATED_OPERAND_CLASS(SubKind, kOperandKind)                       \
-  class SubKind##Operand final : public AllocatedOperand {                   \
-   public:                                                                   \
-    explicit SubKind##Operand(MachineType machine_type, int index)           \
-        : AllocatedOperand(kOperandKind, machine_type, index) {}             \
-                                                                             \
-    static SubKind##Operand* New(Zone* zone, MachineType machine_type,       \
-                                 int index) {                                \
-      return InstructionOperand::New(zone,                                   \
-                                     SubKind##Operand(machine_type, index)); \
-    }                                                                        \
-                                                                             \
-    static SubKind##Operand* cast(InstructionOperand* op) {                  \
-      DCHECK_EQ(kOperandKind, AllocatedOperand::cast(op)->allocated_kind()); \
-      return reinterpret_cast<SubKind##Operand*>(op);                        \
-    }                                                                        \
-                                                                             \
-    static const SubKind##Operand* cast(const InstructionOperand* op) {      \
-      DCHECK_EQ(kOperandKind, AllocatedOperand::cast(op)->allocated_kind()); \
-      return reinterpret_cast<const SubKind##Operand*>(op);                  \
-    }                                                                        \
-                                                                             \
-    static SubKind##Operand cast(const InstructionOperand& op) {             \
-      DCHECK_EQ(kOperandKind, AllocatedOperand::cast(op).allocated_kind());  \
-      return *static_cast<const SubKind##Operand*>(&op);                     \
-    }                                                                        \
-  };
-ALLOCATED_OPERAND_LIST(ALLOCATED_OPERAND_CLASS)
-#undef ALLOCATED_OPERAND_CLASS
-
-
-uint64_t InstructionOperand::GetValueModuloType() const {
-  if (IsAllocated()) {
+uint64_t InstructionOperand::GetCanonicalizedValue() const {
+  if (IsAllocated() || IsExplicit()) {
     // TODO(dcarney): put machine type last and mask.
-    return AllocatedOperand::MachineTypeField::update(this->value_, kMachNone);
+    MachineType canonicalized_machine_type =
+        IsFloatingPoint(LocationOperand::cast(this)->machine_type())
+            ? kMachFloat64
+            : kMachNone;
+    return InstructionOperand::KindField::update(
+        LocationOperand::MachineTypeField::update(this->value_,
+                                                  canonicalized_machine_type),
+        LocationOperand::EXPLICIT);
   }
   return this->value_;
 }
 
 
 // Required for maps that don't care about machine type.
 struct CompareOperandModuloType {
   bool operator()(const InstructionOperand& a,
                   const InstructionOperand& b) const {
-    return a.CompareModuloType(b);
+    return a.CompareCanonicalized(b);
   }
 };
 
 
 class MoveOperands final : public ZoneObject {
  public:
   MoveOperands(const InstructionOperand& source,
                const InstructionOperand& destination)
       : source_(source), destination_(destination) {
     DCHECK(!source.IsInvalid() && !destination.IsInvalid());
@@ skipping 11 matching lines @@
 
   // The gap resolver marks moves as "in-progress" by clearing the
   // destination (but not the source).
   bool IsPending() const {
     return destination_.IsInvalid() && !source_.IsInvalid();
   }
   void SetPending() { destination_ = InstructionOperand(); }
 
   // True if this move a move into the given destination operand.
   bool Blocks(const InstructionOperand& operand) const {
-    return !IsEliminated() && source().EqualsModuloType(operand);
+    return !IsEliminated() && source().EqualsCanonicalized(operand);
   }
 
   // A move is redundant if it's been eliminated or if its source and
   // destination are the same.
   bool IsRedundant() const {
     DCHECK_IMPLIES(!destination_.IsInvalid(), !destination_.IsConstant());
-    return IsEliminated() || source_.EqualsModuloType(destination_);
+    return IsEliminated() || source_.EqualsCanonicalized(destination_);
   }
 
   // We clear both operands to indicate move that's been eliminated.
   void Eliminate() { source_ = destination_ = InstructionOperand(); }
   bool IsEliminated() const {
     DCHECK_IMPLIES(source_.IsInvalid(), destination_.IsInvalid());
     return source_.IsInvalid();
   }
 
  private:
@@ skipping 684 matching lines @@
 
 
 std::ostream& operator<<(std::ostream& os,
                          const PrintableInstructionSequence& code);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_H_