Reflection: Don't emit associated type records for conformances without associated types

This saves a bit of space. We don't care about conformances per se
in remote reflection, only what the associated types are.

Author: slavapestov

lib/IRGen/GenReflection.cpp

@@ -240,13 +240,18 @@ class AssociatedTypeMetadataBuilder : public ReflectionMetadataBuilder {
       return false;
     };
 
+    Conformance->forEachTypeWitness(/*resolver*/ nullptr, collectTypeWitness);
+
+    // If there are no associated types, don't bother emitting any
+    // metadata.
+    if (AssociatedTypes.empty())
+      return;
+
     addTypeRef(ModuleContext, ConformingType);
 
     auto ProtoTy = Conformance->getProtocol()->getDeclaredType();
     addTypeRef(ModuleContext, ProtoTy->getCanonicalType());
 
-    Conformance->forEachTypeWitness(/*resolver*/ nullptr, collectTypeWitness);
-
     addConstantInt32(AssociatedTypes.size());
     addConstantInt32(AssociatedTypeRecordSize);
 

test/Reflection/typeref_decoding.swift

@@ -582,15 +582,10 @@
 
 // CHECK: ASSOCIATED TYPES:
 // CHECK: =================
-// CHECK: - TypesToReflect.Box : Swift.AnyObject
-// CHECK: - TypesToReflect.C : Swift.AnyObject
-// CHECK: - TypesToReflect.C1 : Swift.AnyObject
 // CHECK: - TypesToReflect.C1 : TypesToReflect.ClassBoundP
 // CHECK: typealias Inner = A
 // CHECK: (generic_type_parameter depth=0 index=0)
 
-// CHECK: - TypesToReflect.C2 : Swift.AnyObject
-// CHECK: - TypesToReflect.C3 : Swift.AnyObject
 // CHECK: - TypesToReflect.C4 : TypesToReflect.P1
 // CHECK: typealias Inner = A
 // CHECK: (generic_type_parameter depth=0 index=0)

test/Reflection/typeref_decoding_objc.swift

@@ -22,21 +22,6 @@
 
 // CHECK-32: ASSOCIATED TYPES:
 // CHECK-32: =================
-// CHECK-32: - TypesToReflect.OC : Swift.AnyObject
-// CHECK-32: - TypesToReflect.OC : __ObjC.NSObjectProtocol
-// CHECK-32: - TypesToReflect.OC : Swift.Equatable
-// CHECK-32: - TypesToReflect.OC : Swift.Hashable
-// CHECK-32: - TypesToReflect.OC : Swift.CVarArg
-// CHECK-32: - TypesToReflect.OC : Swift.CustomStringConvertible
-// CHECK-32: - TypesToReflect.OC : Swift.CustomDebugStringConvertible
-// CHECK-32: - TypesToReflect.GenericOC : Swift.AnyObject
-// CHECK-32: - TypesToReflect.GenericOC : __ObjC.NSObjectProtocol
-// CHECK-32: - TypesToReflect.GenericOC : Swift.Equatable
-// CHECK-32: - TypesToReflect.GenericOC : Swift.Hashable
-// CHECK-32: - TypesToReflect.GenericOC : Swift.CVarArg
-// CHECK-32: - TypesToReflect.GenericOC : Swift.CustomStringConvertible
-// CHECK-32: - TypesToReflect.GenericOC : Swift.CustomDebugStringConvertible
-// CHECK-32: - TypesToReflect.HasObjCClasses : Swift.AnyObject
 
 // CHECK-32: BUILTIN TYPES:
 // CHECK-32: ==============
@@ -108,21 +93,6 @@
 
 // CHECK-64: ASSOCIATED TYPES:
 // CHECK-64: =================
-// CHECK-64: - TypesToReflect.OC : Swift.AnyObject
-// CHECK-64: - TypesToReflect.OC : __ObjC.NSObjectProtocol
-// CHECK-64: - TypesToReflect.OC : Swift.Equatable
-// CHECK-64: - TypesToReflect.OC : Swift.Hashable
-// CHECK-64: - TypesToReflect.OC : Swift.CVarArg
-// CHECK-64: - TypesToReflect.OC : Swift.CustomStringConvertible
-// CHECK-64: - TypesToReflect.OC : Swift.CustomDebugStringConvertible
-// CHECK-64: - TypesToReflect.GenericOC : Swift.AnyObject
-// CHECK-64: - TypesToReflect.GenericOC : __ObjC.NSObjectProtocol
-// CHECK-64: - TypesToReflect.GenericOC : Swift.Equatable
-// CHECK-64: - TypesToReflect.GenericOC : Swift.Hashable
-// CHECK-64: - TypesToReflect.GenericOC : Swift.CVarArg
-// CHECK-64: - TypesToReflect.GenericOC : Swift.CustomStringConvertible
-// CHECK-64: - TypesToReflect.GenericOC : Swift.CustomDebugStringConvertible
-// CHECK-64: - TypesToReflect.HasObjCClasses : Swift.AnyObject
 
 // CHECK-64: BUILTIN TYPES:
 // CHECK-64: ==============