[sil-verifier] Verify correctly that lowered SIL optional types are lowered types of formal optional types.

lib/AST/ASTDumper.cpp

@@ -2753,29 +2753,34 @@ namespace {
       OS << ")";
     }
 
+    void printMetatypeRepresentation(MetatypeRepresentation representation) {
+      OS << " ";
+      switch (representation) {
+      case MetatypeRepresentation::Thin:
+        OS << "@thin";
+        break;
+      case MetatypeRepresentation::Thick:
+        OS << "@thick";
+        break;
+      case MetatypeRepresentation::ObjC:
+        OS << "@objc";
+        break;
+      }
+    }
+
     void visitMetatypeType(MetatypeType *T, StringRef label) {
       printCommon(T, label, "metatype_type");
-      if (T->hasRepresentation()) {
-        OS << " ";
-        switch (T->getRepresentation()) {
-        case MetatypeRepresentation::Thin:
-          OS << "@thin";
-          break;
-        case MetatypeRepresentation::Thick:
-          OS << "@thick";
-          break;
-        case MetatypeRepresentation::ObjC:
-          OS << "@objc";
-          break;
-        }
-      }
+      if (T->hasRepresentation())
+        printMetatypeRepresentation(T->getRepresentation());
       printRec(T->getInstanceType());
       OS << ")";
     }
 
     void visitExistentialMetatypeType(ExistentialMetatypeType *T,
                                       StringRef label) {
       printCommon(T, label, "existential_metatype_type");
+      if (T->hasRepresentation())
+        printMetatypeRepresentation(T->getRepresentation());
       printRec(T->getInstanceType());
       OS << ")";
     }

lib/SIL/SILVerifier.cpp

@@ -1491,8 +1491,9 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
       if (auto dynamicSelf = dyn_cast<DynamicSelfType>(formalObjectType)) {
         formalObjectType = dynamicSelf->getSelfType()->getCanonicalType();
       }
-      return ((loweredOptionalKind == formalOptionalKind) &&
-              loweredObjectType == formalObjectType);
+      return loweredOptionalKind == formalOptionalKind &&
+             isLoweringOf(SILType::getPrimitiveAddressType(loweredObjectType),
+                          formalObjectType);
     }
 
     // Metatypes preserve their instance type through lowering.

test/SIL/verifier-value-metatype-lowering.sil

@@ -0,0 +1,22 @@
+// RUN: %target-sil-opt -module-name Swift %s
+// REQUIRES: asserts
+//
+// Make sure that we properly verify the lowering of optional value
+// metatypes. This shouldn't crash.
+//
+// rdar://28536812
+
+enum Optional<T> {
+case none
+case some(T)
+}
+
+sil @foo : $@convention(thin) () -> () {
+  %0 = enum $Optional<@thick Any.Type>, #Optional.none!enumelt
+  %1 = alloc_stack $Optional<@thick Any.Type>
+  store %0 to %1 : $*Optional<@thick Any.Type>
+  %2 = value_metatype $@thick Optional<Any.Type>.Type, %1 : $*Optional<@thick Any.Type>
+  dealloc_stack %1 : $*Optional<@thick Any.Type>
+  %3 = tuple()
+  return %3 : $()
+}