remove (now unused) TypeLowering::isValid()

Author: dduan

include/swift/SIL/TypeLowering.h

@@ -151,12 +151,6 @@ class TypeLowering {
     return !isAddressOnly();
   }
 
-  /// True if the type was successfully lowered, false if there was an error
-  /// during type lowering.
-  virtual bool isValid() const {
-    return true;
-  }
-  
   /// Returns true if the type is trivial, meaning it is a loadable
   /// value type with no reference type members that require releasing.
   bool isTrivial() const {

lib/SILOptimizer/Mandatory/PredictableMemOpt.cpp

@@ -41,8 +41,6 @@ getFullyReferenceableStruct(SILType Ty) {
 }
 
 static unsigned getNumSubElements(SILType T, SILModule &M) {
-  if (!M.getTypeLowering(T).isValid())
-    return 0;
 
   if (auto TT = T.getAs<TupleType>()) {
     unsigned NumElements = 0;