Merge pull request #26251 from jckarter/opaque-associated-type-witness-protocol-refinement-5.1

[5.1] IRGen: Use correct archetype conformance code path for opaque associated types.

Author: jckarter

lib/IRGen/GenMeta.cpp

@@ -1690,8 +1690,6 @@ namespace {
       auto opaqueType = O->getDeclaredInterfaceType()
                          ->castTo<OpaqueTypeArchetypeType>();
 
-      
-      
       for (auto proto : opaqueType->getConformsTo()) {
         auto conformance = ProtocolConformanceRef(proto);
         auto underlyingConformance = conformance

lib/IRGen/GenProto.cpp

@@ -1565,17 +1565,6 @@ void WitnessTableBuilder::defineAssociatedTypeWitnessTableAccessFunction(
   IGF.bindLocalTypeDataFromTypeMetadata(ConcreteType, IsExact, self,
                                         MetadataState::Abstract);
 
-  // If the associated type is opaque, use the runtime to fetch the conformance.
-  if (associatedRootOpaqueType) {
-    assert(associatedType == CanType(associatedRootOpaqueType)
-           && "associated type is nested type of opaque type?! not implemented");
-    auto wtable = emitOpaqueTypeWitnessTableRef(IGF,
-                          CanOpaqueTypeArchetypeType(associatedRootOpaqueType),
-                          associatedProtocol);
-    IGF.Builder.CreateRet(wtable);
-    return;
-  }
-  
   // Find abstract conformances.
   // TODO: provide an API to find the best metadata path to the conformance
   // and decide whether it's expensive enough to be worth caching.

test/IRGen/opaque_result_type_associated_type_conformance_path.swift

@@ -0,0 +1,22 @@
+// RUN: %target-swift-frontend -disable-availability-checking -emit-ir %s | %FileCheck %s
+
+protocol Butt { }
+
+protocol Tubb: Butt { }
+
+protocol P {
+  associatedtype A: Butt
+  associatedtype B: Butt
+  func foo(_ x: A) -> B
+}
+
+struct Foo<T: Tubb>: P {
+  func foo(_ x: T) -> some Tubb { return x }
+}
+
+// CHECK-LABEL: define {{.*}} @"$s030opaque_result_type_associated_C17_conformance_path3FooVyxGAA1PAA1B_AA4ButtPWT"
+// CHECK: [[TUBB_CONFORMANCE:%.*]] = call swiftcc i8** @swift_getOpaqueTypeConformance({{.*}}, i{{.*}} 1)
+// CHECK: [[BUTT_CONFORMANCE_ADDR:%.*]] = getelementptr {{.*}} [[TUBB_CONFORMANCE]], i32 1
+// CHECK: [[BUTT_CONFORMANCE_LOAD:%.*]] = load {{.*}} [[BUTT_CONFORMANCE_ADDR]]
+// CHECK: [[BUTT_CONFORMANCE:%.*]] = bitcast {{.*}} [[BUTT_CONFORMANCE_LOAD]]
+// CHECK: ret {{.*}} [[BUTT_CONFORMANCE]]