[turbofan]: Add better encapsulation to LinkageLocation

src/compiler/linkage-impl.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_LINKAGE_IMPL_H_
 #define V8_COMPILER_LINKAGE_IMPL_H_
 
 #include "src/code-stubs.h"
 #include "src/compiler/osr.h"
 
@@ skipping 104 matching lines @@
     // Add context.
     locations.AddParam(regloc(LinkageTraits::ContextReg()));
     types.AddParam(kMachAnyTagged);
 
     CallDescriptor::Flags flags = Linkage::FrameStateInputCount(function_id) > 0
                                       ? CallDescriptor::kNeedsFrameState
                                       : CallDescriptor::kNoFlags;
 
     // The target for runtime calls is a code object.
     MachineType target_type = kMachAnyTagged;
-    LinkageLocation target_loc = LinkageLocation::AnyRegister();
+    LinkageLocation target_loc = LinkageLocation::ForAnyRegister();
     return new (zone) CallDescriptor(     // --
         CallDescriptor::kCallCodeObject,  // kind
         target_type,                      // target MachineType
         target_loc,                       // target location
         types.Build(),                    // machine_sig
         locations.Build(),                // location_sig
         js_parameter_count,               // js_parameter_count
         properties,                       // properties
         kNoCalleeSaved,                   // callee-saved
         kNoCalleeSaved,                   // callee-saved fp
@@ skipping 39 matching lines @@
         locations.AddParam(stackloc(stack_slot));
         types.AddParam(kMachAnyTagged);
       }
     }
     // Add context.
     locations.AddParam(regloc(LinkageTraits::ContextReg()));
     types.AddParam(kMachAnyTagged);
 
     // The target for stub calls is a code object.
     MachineType target_type = kMachAnyTagged;
-    LinkageLocation target_loc = LinkageLocation::AnyRegister();
+    LinkageLocation target_loc = LinkageLocation::ForAnyRegister();
     return new (zone) CallDescriptor(     // --
         CallDescriptor::kCallCodeObject,  // kind
         target_type,                      // target MachineType
         target_loc,                       // target location
         types.Build(),                    // machine_sig
         locations.Build(),                // location_sig
         js_parameter_count,               // js_parameter_count
         properties,                       // properties
         kNoCalleeSaved,                   // callee-saved registers
         kNoCalleeSaved,                   // callee-saved fp
@@ skipping 11 matching lines @@
     locations.AddParam(regloc(LinkageTraits::InterpreterBytecodeOffsetReg()));
 
     STATIC_ASSERT(1 == Linkage::kInterpreterBytecodeArrayParameter);
     types.AddParam(kMachAnyTagged);
     locations.AddParam(regloc(LinkageTraits::InterpreterBytecodeArrayReg()));
 
     STATIC_ASSERT(2 == Linkage::kInterpreterDispatchTableParameter);
     types.AddParam(kMachPtr);
     locations.AddParam(regloc(LinkageTraits::InterpreterDispatchTableReg()));
 
-    LinkageLocation target_loc = LinkageLocation::AnyRegister();
+    LinkageLocation target_loc = LinkageLocation::ForAnyRegister();
     return new (zone) CallDescriptor(          // --
         CallDescriptor::kInterpreterDispatch,  // kind
         kMachNone,                             // target MachineType
         target_loc,                            // target location
         types.Build(),                         // machine_sig
         locations.Build(),                     // location_sig
         0,                                     // js_parameter_count
         Operator::kNoProperties,               // properties
         kNoCalleeSaved,                        // callee-saved registers
         kNoCalleeSaved,                        // callee-saved fp regs
         CallDescriptor::kSupportsTailCalls,    // flags
         "interpreter-dispatch");
   }
 
   static LinkageLocation regloc(Register reg) {
-    return LinkageLocation(Register::ToAllocationIndex(reg));
+    return LinkageLocation::ForRegister(Register::ToAllocationIndex(reg));
   }
 
   static LinkageLocation stackloc(int i) {
-    DCHECK_LT(i, 0);
-    return LinkageLocation(i);
+    return LinkageLocation::ForCallerFrameSlot(i);
   }
 
   static MachineType reptyp(Representation representation) {
     switch (representation.kind()) {
       case Representation::kInteger8:
         return kMachInt8;
       case Representation::kUInteger8:
         return kMachUint8;
       case Representation::kInteger16:
         return kMachInt16;
@@ skipping 24 matching lines @@
   int parameter_count = static_cast<int>(incoming_->JSParameterCount() - 1);
   int first_stack_slot = OsrHelper::FirstStackSlotIndex(parameter_count);
 
   if (index == kOsrContextSpillSlotIndex) {
     // Context. Use the parameter location of the context spill slot.
     // Parameter (arity + 1) is special for the context of the function frame.
     int context_index = 1 + 1 + parameter_count;  // target + receiver + params
     return incoming_->GetInputLocation(context_index);
   } else if (index >= first_stack_slot) {
     // Local variable stored in this (callee) stack.
-    int spill_index =
-        LinkageLocation::ANY_REGISTER + 1 + index - first_stack_slot;
-    // TODO(titzer): bailout instead of crashing here.
-    CHECK(spill_index <= LinkageLocation::MAX_STACK_SLOT);
-    return LinkageLocation(spill_index);
+    int spill_index = index - first_stack_slot;
+    return LinkageLocation::ForCalleeFrameSlot(spill_index);
   } else {
     // Parameter. Use the assigned location from the incoming call descriptor.
     int parameter_index = 1 + index;  // skip index 0, which is the target.
     return incoming_->GetInputLocation(parameter_index);
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_LINKAGE_IMPL_H_