[IRGen] Enabled mangled inherited conformances for conditional conformances.

Now that the runtime fills in the private slots with conditional requirement
information, we can always use mangled names for inherited conformances.

Fixes rdar://problem/46282080.

(cherry picked from commit e52a883)

Author: DougGregor

lib/IRGen/GenProto.cpp

@@ -1346,29 +1346,18 @@ class AccessorConformanceInfo : public ConformanceInfo {
         return;
       }
 
-      // If this isn't a conditional conformance, we can emit a mangled name.
-      // FIXME: Conditional conformances won't currently work because the
-      // witness tables for conditional requirements won't have been written
-      // into the private area yet.
-      if (SILConditionalConformances.empty()) {
-        if (isDependentConformance(astConf->getRootConformance(),
-                                   /*considerResilience=*/false))
-          RequiresSpecialization = true;
-
-        auto proto = Conformance.getProtocol();
-        CanType selfType = proto->getProtocolSelfType()->getCanonicalType();
-        AssociatedConformance requirement(proto, selfType, baseProto);
-        llvm::Constant *witnessEntry =
-          getAssociatedConformanceWitness(requirement, ConcreteType,
-                                          ProtocolConformanceRef(astConf));
-        Table.addBitCast(witnessEntry, IGM.Int8PtrTy);
-        return;
-      }
+      // Emit a mangled name.
+      if (isDependentConformance(astConf->getRootConformance(),
+                                 /*considerResilience=*/false))
+        RequiresSpecialization = true;
 
-      // Otherwise, we'll need to derive it at instantiation time.
-      RequiresSpecialization = true;
-      SpecializedBaseConformances.push_back({Table.size(), &conf});
-      Table.addNullPointer(IGM.Int8PtrTy);
+      auto proto = Conformance.getProtocol();
+      CanType selfType = proto->getProtocolSelfType()->getCanonicalType();
+      AssociatedConformance requirement(proto, selfType, baseProto);
+      llvm::Constant *witnessEntry =
+        getAssociatedConformanceWitness(requirement, ConcreteType,
+                                        ProtocolConformanceRef(astConf));
+      Table.addBitCast(witnessEntry, IGM.Int8PtrTy);
     }
 
     void addMethod(SILDeclRef requirement) {

test/Inputs/conditional_conformance_recursive.swift

@@ -18,11 +18,6 @@ protocol P3: P2 where A: P3 { }
 
 extension Wrapper: P3 where T: P3 { }
 
-// instantiation function for Wrapper<T>: P3
-// CHECK-LABEL: define internal void @"$s33conditional_conformance_recursive7WrapperVyxGAA2P3A2aERzrlWI"
-// CHECK-NOT: ret
-// CHECK: call i8** @swift_getWitnessTable
-
 // associated type witness table accessor for A : P2 in Wrapper<T>: P2
 // CHECK-LABEL: define internal swiftcc i8** @"$s33conditional_conformance_recursive7WrapperVyxGAA2P2A2aERzrl1A_AaEPWT"
 // CHECK: [[CONDITIONAL_REQ_BUFFER:%.*]] = alloca [1 x i8**]

test/Inputs/conditional_conformance_with_assoc.swift

@@ -234,13 +234,3 @@ extension X: Base where T: Base { }
 extension X: Sub where T: Sub, T.S == T {
    typealias S = X<T>
 }
-
-// Make sure we can recover the type metadata from X<T>.Type.
-// CHECK: define internal void @"$s34conditional_conformance_with_assoc1XVyxGAA3SubA2aERz1SQzRszlWI"(i8**, %swift.type* %"X<T>", i8**)
-// CHECK: entry:
-// CHECK:   [[XT_TYPE:%.*]] = bitcast %swift.type* %"X<T>" to %swift.type**
-// CHECK:   [[ADDR:%.*]] = getelementptr inbounds %swift.type*, %swift.type** [[XT_TYPE]], i64 2
-// CHECK:   [[T:%.*]] = load %swift.type*, %swift.type** [[ADDR]]
-// CHECK:   %T.Base = call swiftcc i8** @swift_getAssociatedConformanceWitness(i8** {{.*}}, %swift.type* %T, %swift.type* %T
-// CHECK:   ret void
-// CHECK: }