[Turbofan] Make RegisterAllocatorVerifier tolerant of shared slots.

src/compiler/register-allocator-verifier.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_REGISTER_ALLOCATOR_VERIFIER_H_
 #define V8_REGISTER_ALLOCATOR_VERIFIER_H_
 
 #include "src/zone-containers.h"
 
 namespace v8 {
@@ skipping 160 matching lines @@
 
  private:
   enum ConstraintType {
     kConstant,
     kImmediate,
     kRegister,
     kFixedRegister,
     kFPRegister,
     kFixedFPRegister,
     kSlot,
-    kFPSlot,
     kFixedSlot,
     kNone,
     kNoneFP,
     kExplicit,
     kSameAsFirst,
     kRegisterAndSlot
   };
 
   struct OperandConstraint {
     ConstraintType type_;
-    int value_;  // subkind index when relevant
+    // Constant or immediate value, register code, slot index, or slot size
+    // when relevant.
+    int value_;
     int spilled_slot_;
     int virtual_register_;
   };
 
   struct InstructionConstraint {
     const Instruction* instruction_;
     size_t operand_constaints_size_;
     OperandConstraint* operand_constraints_;
   };
 
@@ skipping 54 matching lines @@
   ZoneMap<RpoNumber, DelayedAssessments*> outstanding_assessments_;
 
   DISALLOW_COPY_AND_ASSIGN(RegisterAllocatorVerifier);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif