Fix bug in ParallelMoveResolver::EmitSwap: implement swaps of FPU spill slots.

runtime/vm/locations.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_LOCATIONS_H_
 #define VM_LOCATIONS_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/bitfield.h"
@@ skipping 17 matching lines @@
 
 
 // Location objects are used to connect register allocator and code generator.
 // Instruction templates used by code generator have a corresponding
 // LocationSummary object which specifies expected location for every input
 // and output.
 // Each location is encoded as a single word: for non-constant locations
 // low 3 bits denote location kind, rest is kind specific location payload
 // e.g. for REGISTER kind payload is register code (value of the Register
 // enumeration), constant locations contain a tagged (low 2 bits are set to 01)
-// Object handle
+// Object handle.
+//
+// Locations must satisfy the following invariant: if two locations' encodings
+// are bitwise unequal then these two locations are guaranteed to be disjoint.
+// Properties like representation belong to the value that is stored in
+// the location not to the location itself.
 class Location : public ValueObject {
  private:
   enum {
     // Number of bits required to encode Kind value.
     kBitsForKind = 4,
     kBitsForPayload = kWordSize * kBitsPerByte - kBitsForKind,
   };
 
   static const uword kInvalidLocation = 0;
   static const uword kConstantMask = 0x3;
 
   static const intptr_t kMachineRegisterMask = 0x6;
   static const intptr_t kMachineRegister = 0x6;
 
  public:
   // Constant payload can overlap with kind field so Kind values
   // have to be chosen in a way that their last 2 bits are never
   // the same as kConstant.
+  // Note that two locations with different kinds should never point to
+  // the same place. For example kQuadStackSlot location should never intersect
+  // with kDoubleStackSlot location.
   enum Kind {
     // This location is invalid.  Payload must be zero.
     kInvalid = 0,
 
     // Constant value. This location contains a tagged Object handle.
     kConstant = 1,
 
     // Unallocated location represents a location that is not fixed and can be
     // allocated by a register allocator.  Each unallocated location has
     // a policy that specifies what kind of location is suitable. Payload
     // contains register allocation policy.
     kUnallocated = 2,
 
-    // Spill slot allocated by the register allocator.  Payload contains
+    // Spill slots allocated by the register allocator.  Payload contains
     // a spill index.
-    kStackSlot = 3,
-    kDoubleStackSlot = 4,
-    kFloat32x4StackSlot = 8,
-    kUint32x4StackSlot = 10,
+    kStackSlot = 3,  // Word size slot.
+    kDoubleStackSlot = 4,  // 64bit stack slot.
+    kQuadStackSlot = 8,  // 128bit stack slot.
 
     // Register location represents a fixed register.  Payload contains
     // register code.
     kRegister = 6,
 
     // FpuRegister location represents a fixed fpu register.  Payload contains
     // its code.
     kFpuRegister = 7,
   };
 
@@ skipping 82 matching lines @@
   static Location NoLocation() {
     return Location();
   }
 
   Policy policy() const {
     ASSERT(IsUnallocated());
     return PolicyField::decode(payload());
   }
 
   // Register locations.
-  static Location RegisterLocation(Register reg, Representation rep = kTagged) {
-    uword payload =
-        RegisterField::encode(reg) |
-        RepresentationField::encode(rep);
-    return Location(kRegister, payload);
+  static Location RegisterLocation(Register reg) {
+    return Location(kRegister, reg);
   }
 
   bool IsRegister() const {
     return kind() == kRegister;
   }
 
   Register reg() const {
     ASSERT(IsRegister());
-    return RegisterField::decode(payload());
-  }
-
-
-  Representation representation() const {
-    return RepresentationField::decode(payload());
+    return static_cast<Register>(payload());
   }
 
   // FpuRegister locations.
-  static Location FpuRegisterLocation(FpuRegister reg, Representation rep) {
-    uword payload =
-        FpuRegisterField::encode(reg) | RepresentationField::encode(rep);
-    return Location(kFpuRegister, payload);
+  static Location FpuRegisterLocation(FpuRegister reg) {
+    return Location(kFpuRegister, reg);
   }
 
   bool IsFpuRegister() const {
     return kind() == kFpuRegister;
   }
 
   FpuRegister fpu_reg() const {
     ASSERT(IsFpuRegister());
-    return FpuRegisterField::decode(payload());
+    return static_cast<FpuRegister>(payload());
   }
 
   static bool IsMachineRegisterKind(Kind kind) {
     return (kind & kMachineRegisterMask) == kMachineRegister;
   }
 
   static Location MachineRegisterLocation(Kind kind,
-                                          intptr_t reg,
-                                          Representation rep) {
+                                          intptr_t reg) {
     if (kind == kRegister) {
       return RegisterLocation(static_cast<Register>(reg));
     } else {
       ASSERT(kind == kFpuRegister);
-      return FpuRegisterLocation(static_cast<FpuRegister>(reg), rep);
+      return FpuRegisterLocation(static_cast<FpuRegister>(reg));
     }
   }
 
   bool IsMachineRegister() const {
     return IsMachineRegisterKind(kind());
   }
 
   intptr_t register_code() const {
     ASSERT(IsMachineRegister());
-    return static_cast<intptr_t>(RegisterField::decode(payload()));
+    return static_cast<intptr_t>(payload());
   }
 
-  static uword make_stack_index_payload(intptr_t stack_index,
-                                        Representation rep) {
+  static uword EncodeStackIndex(intptr_t stack_index) {
     ASSERT((-kStackIndexBias <= stack_index) &&
-       (stack_index < kStackIndexBias));
-    uword payload =
-      IndexField::encode(static_cast<uword>(kStackIndexBias + stack_index));
-    return payload | RepresentationField::encode(rep);
+           (stack_index < kStackIndexBias));
+    return static_cast<uword>(kStackIndexBias + stack_index);
   }
 
   // Spill slots.
-  static Location StackSlot(intptr_t stack_index,
-                            Representation rep = kTagged) {
-    uword payload = make_stack_index_payload(stack_index, rep);
+  static Location StackSlot(intptr_t stack_index) {
+    uword payload = EncodeStackIndex(stack_index);
     Location loc(kStackSlot, payload);
     // Ensure that sign is preserved.
     ASSERT(loc.stack_index() == stack_index);
     return loc;
   }
 
   bool IsStackSlot() const {
     return kind() == kStackSlot;
   }
 
-  static Location DoubleStackSlot(intptr_t stack_index, Representation rep) {
-    uword payload = make_stack_index_payload(stack_index, rep);
+  static Location DoubleStackSlot(intptr_t stack_index) {
+    uword payload = EncodeStackIndex(stack_index);
     Location loc(kDoubleStackSlot, payload);
     // Ensure that sign is preserved.
     ASSERT(loc.stack_index() == stack_index);
     return loc;
   }
 
   bool IsDoubleStackSlot() const {
     return kind() == kDoubleStackSlot;
   }
 
-  static Location Float32x4StackSlot(intptr_t stack_index) {
-    uword payload = make_stack_index_payload(stack_index, kUnboxedFloat32x4);
-    Location loc(kFloat32x4StackSlot, payload);
+  static Location QuadStackSlot(intptr_t stack_index) {
+    uword payload = EncodeStackIndex(stack_index);
+    Location loc(kQuadStackSlot, payload);
     // Ensure that sign is preserved.
     ASSERT(loc.stack_index() == stack_index);
     return loc;
   }
 
-  bool IsFloat32x4StackSlot() const {
-    return kind() == kFloat32x4StackSlot;
+  bool IsQuadStackSlot() const {
+    return kind() == kQuadStackSlot;
   }
 
-  static Location Uint32x4StackSlot(intptr_t stack_index) {
-    uword payload = make_stack_index_payload(stack_index, kUnboxedUint32x4);
-    Location loc(kUint32x4StackSlot, payload);
-    // Ensure that sign is preserved.
-    ASSERT(loc.stack_index() == stack_index);
-    return loc;
-  }
-
-  bool IsUint32x4StackSlot() const {
-    return kind() == kUint32x4StackSlot;
-  }
-
-
   intptr_t stack_index() const {
-    ASSERT(IsStackSlot() || IsDoubleStackSlot() || IsFloat32x4StackSlot() ||
-           IsUint32x4StackSlot());
+    ASSERT(IsStackSlot() || IsDoubleStackSlot() || IsQuadStackSlot());
     // Decode stack index manually to preserve sign.
-    return IndexField::decode(payload()) - kStackIndexBias;
+    return payload() - kStackIndexBias;
   }
 
   // Return a memory operand for stack slot locations.
   Address ToStackSlotAddress() const;
 
   // Constants.
   static Location RegisterOrConstant(Value* value);
   static Location RegisterOrSmiConstant(Value* value);
   static Location FixedRegisterOrConstant(Value* value, Register reg);
   static Location FixedRegisterOrSmiConstant(Value* value, Register reg);
@@ skipping 23 matching lines @@
   uword payload() const {
     return PayloadField::decode(value_);
   }
 
   typedef BitField<Kind, 0, kBitsForKind> KindField;
   typedef BitField<uword, kBitsForKind, kBitsForPayload> PayloadField;
 
   // Layout for kUnallocated locations payload.
   typedef BitField<Policy, 0, 3> PolicyField;
 
-  // Layout for register locations payload.
-  static const intptr_t kBitsForRepresentation = 3;
-  COMPILE_ASSERT(kNumRepresentations <= (1 << kBitsForRepresentation),
-                 invalid_enum);
-  static const intptr_t kBitsForRegister =
-      kBitsForPayload - kBitsForRepresentation;
-  typedef BitField<Representation,
-                   0,
-                   kBitsForRepresentation> RepresentationField;
-  typedef BitField<Register,
-                   kBitsForRepresentation,
-                   kBitsForRegister> RegisterField;
-  typedef BitField<FpuRegister,
-                   kBitsForRepresentation,
-                   kBitsForRegister> FpuRegisterField;
-
   // Layout for stack slots.
-  static const intptr_t kBitsForIndex =
-      kBitsForPayload - kBitsForRepresentation;
-  typedef BitField<uword,
-                   kBitsForRepresentation,
-                   kBitsForIndex> IndexField;
   static const intptr_t kStackIndexBias =
-      static_cast<intptr_t>(1) << (kBitsForIndex - 1);
+      static_cast<intptr_t>(1) << (kBitsForPayload - 1);
 
   // Location either contains kind and payload fields or a tagged handle for
   // a constant locations. Values of enumeration Kind are selected in such a
   // way that none of them can be interpreted as a kConstant tag.
   uword value_;
 };
 
 
 class RegisterSet : public ValueObject {
  public:
@@ skipping 141 matching lines @@
   BitmapBuilder* stack_bitmap_;
 
   const ContainsCall contains_call_;
   RegisterSet live_registers_;
 };
 
 
 }  // namespace dart
 
 #endif  // VM_LOCATIONS_H_