Set DNER for all local fields (#77341)

Not just the promoted ones.

src/coreclr/jit/morph.cpp

@@ -16386,10 +16386,6 @@ void Compiler::fgMorphLocalField(GenTree* tree, GenTree* parent)
             }
             else
             {
-                // There is no existing field that has all the parts that we need
-                // So we must ensure that the struct lives in memory.
-                lvaSetVarDoNotEnregister(lclNum DEBUGARG(DoNotEnregisterReason::LocalField));
-
 #ifdef DEBUG
                 // We can't convert this guy to a float because he really does have his
                 // address taken..
@@ -16405,6 +16401,12 @@ void Compiler::fgMorphLocalField(GenTree* tree, GenTree* parent)
             JITDUMP("Replacing GT_LCL_FLD of struct with local var V%02u\n", lclNum);
         }
     }
+
+    // If we haven't replaced the field, make sure to set DNER on the local.
+    if (tree->OperIs(GT_LCL_FLD))
+    {
+        lvaSetVarDoNotEnregister(lclNum DEBUGARG(DoNotEnregisterReason::LocalField));
+    }
 }
 
 //------------------------------------------------------------------------