Disable cast optimization for address-only types.

The code gen assumes the type is loadable. Disable for now to avoid bugs.

Author: jckarter

include/swift/SIL/SILBuilder.h

@@ -424,6 +424,7 @@ class SILBuilder {
   }
 
   LoadInst *createLoad(SILLocation Loc, SILValue LV) {
+    assert(LV->getType().isLoadable(F.getModule()));
     return insert(new (F.getModule())
                       LoadInst(getSILDebugLocation(Loc), LV));
   }

lib/SILOptimizer/Utils/Local.cpp

@@ -1426,6 +1426,11 @@ optimizeBridgedObjCToSwiftCast(SILInstruction *Inst,
   assert(Src->getType().isAddress() && "Source should have an address type");
   assert(Dest->getType().isAddress() && "Source should have an address type");
 
+  if (!Src->getType().isLoadable(M) || !Dest->getType().isLoadable(M)) {
+    // TODO: Handle address only types.
+    return nullptr;
+  }
+
   if (SILBridgedTy != Src->getType()) {
     // Check if we can simplify a cast into:
     // - ObjCTy to _ObjectiveCBridgeable._ObjectiveCType.
@@ -1603,6 +1608,11 @@ optimizeBridgedSwiftToObjCCast(SILInstruction *Inst,
 
   auto &M = Inst->getModule();
   auto Loc = Inst->getLoc();
+  
+  if (!Src->getType().isLoadable(M) || !Dest->getType().isLoadable(M)) {
+    // TODO: Handle address-only types.
+    return nullptr;
+  }
 
   // Find the _BridgedToObjectiveC protocol.
   auto BridgedProto =