[turbofan]: Add better encapsulation to LinkageLocation

src/compiler/instruction-selector-impl.h

Index: src/compiler/instruction-selector-impl.h
diff --git a/src/compiler/instruction-selector-impl.h b/src/compiler/instruction-selector-impl.h
index b34a914efcca285a4a80aa6470be2b16a7d8893b..db9e100e018b429a8718475d348a795b51292035 100644
--- a/src/compiler/instruction-selector-impl.h
+++ b/src/compiler/instruction-selector-impl.h
@@ -208,30 +208,28 @@ class OperandGenerator {
   UnallocatedOperand ToUnallocatedOperand(LinkageLocation location,
                                           MachineType type,
                                           int virtual_register) {
-    if (location.location_ == LinkageLocation::ANY_REGISTER) {
+    if (location.IsAnyRegister()) {
       // any machine register.
       return UnallocatedOperand(UnallocatedOperand::MUST_HAVE_REGISTER,
                                 virtual_register);
     }
-    if (location.location_ < 0) {
+    if (location.IsCallerFrameSlot()) {
       // a location on the caller frame.
       return UnallocatedOperand(UnallocatedOperand::FIXED_SLOT,
-                                location.location_, virtual_register);
+                                location.AsCallerFrameSlot(), virtual_register);
     }
-    if (location.location_ > LinkageLocation::ANY_REGISTER) {
+    if (location.IsCalleeFrameSlot()) {
       // a spill location on this (callee) frame.
-      return UnallocatedOperand(
-          UnallocatedOperand::FIXED_SLOT,
-          location.location_ - LinkageLocation::ANY_REGISTER - 1,
-          virtual_register);
+      return UnallocatedOperand(UnallocatedOperand::FIXED_SLOT,
+                                location.AsCalleeFrameSlot(), virtual_register);
     }
     // a fixed register.
     if (RepresentationOf(type) == kRepFloat64) {
       return UnallocatedOperand(UnallocatedOperand::FIXED_DOUBLE_REGISTER,
-                                location.location_, virtual_register);
+                                location.AsRegister(), virtual_register);
     }
     return UnallocatedOperand(UnallocatedOperand::FIXED_REGISTER,
-                              location.location_, virtual_register);
+                              location.AsRegister(), virtual_register);
   }
 
   InstructionSelector* selector_;