[IRGen] Metadata for the conforming type in a witness table access need not be complete.

When calling a witness table accessor, IRGen was forcing the
conforming type to have complete metadata, even though only abstract
metadata is required for that query. This could cause cyclic metadata
dependencies when checking conditional conformances.

Fixes SR-5958.

lib/IRGen/GenProto.cpp

@@ -1114,7 +1114,7 @@ static llvm::Value *emitWitnessTableAccessorCall(
 
   // Emit the source metadata if we haven't yet.
   if (!*srcMetadataCache) {
-    *srcMetadataCache = IGF.emitTypeMetadataRef(
+    *srcMetadataCache = IGF.emitAbstractTypeMetadataRef(
       conformance->getType()->getCanonicalType());
   }
 

test/IRGen/witness_method.sil

@@ -64,12 +64,14 @@ struct SyncUp<Deliverable> : Synergy {
 
 // CHECK-LABEL: define{{( dllexport)?}}{{( protected)?}} swiftcc void @testGenericWitnessMethod(%swift.opaque* noalias nocapture sret, %T14witness_method6SyncUpV* noalias nocapture, %swift.type* %T)
 // CHECK: entry:
-// CHECK:   [[TMP:%.*]] = call swiftcc %swift.metadata_response @"$s14witness_method6SyncUpVMa"([[INT]] 0, %swift.type* %T)
+// CHECK:   [[TMP:%.*]] = call swiftcc %swift.metadata_response @"$s14witness_method6SyncUpVMa"([[INT]] 255, %swift.type* %T)
 // CHECK:   [[METADATA:%.*]] = extractvalue %swift.metadata_response [[TMP]], 0
 // CHECK:   [[WTABLE:%.*]] = call i8** @swift_getWitnessTable(
 // CHECK:   [[WITNESS_ADDR:%.*]] = getelementptr inbounds i8*, i8** [[WTABLE]], i32 2
 // CHECK:   [[WITNESS_FN:%.*]] = load i8*, i8** [[WITNESS_ADDR]]
 // CHECK:   [[WITNESS:%.*]] = bitcast i8* [[WITNESS_FN]] to void (%swift.opaque*, %swift.opaque*, %swift.type*, i8**)*
+// CHECK:   [[TMP:%.*]] = call swiftcc %swift.metadata_response @swift_checkMetadataState(i64 0, %swift.type* [[METADATA]])
+// CHECK:   [[METADATA:%.*]] = extractvalue %swift.metadata_response [[TMP]], 0
 // CHECK:   [[ARG:%.*]] = bitcast %T14witness_method6SyncUpV* %1 to %swift.opaque*
 // CHECK:   call swiftcc void [[WITNESS]](%swift.opaque* noalias nocapture sret %0, %swift.opaque* noalias nocapture swiftself [[ARG]], %swift.type* [[METADATA]], i8** [[WTABLE]])
 // CHECK:   ret void

test/Inputs/conditional_conformance_basic_conformances.swift

@@ -84,10 +84,10 @@ public func single_concrete() {
 // CHECK-NEXT:    br i1 [[IS_NULL]], label %cacheIsNull, label %cont
 
 // CHECK:       cacheIsNull:
-// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s42conditional_conformance_basic_conformances6SingleVyAA4IsP2VGMa"(i64 0)
+// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s42conditional_conformance_basic_conformances6SingleVyAA4IsP2VGMa"(i64 255)
 // CHECK-NEXT:    [[Single_TYPE:%.*]] = extractvalue %swift.metadata_response [[T0]], 0
 
-// CHECK-NEXT:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [1 x i8**], [1 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
+// CHECK:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [1 x i8**], [1 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
 // CHECK-NEXT:    [[A_P2_PTR:%.*]] = getelementptr inbounds i8**, i8*** [[CONDITIONAL_REQUIREMENTS]], i32 0
 // CHECK-NEXT:    store i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @"$s42conditional_conformance_basic_conformances4IsP2VAA0F0AAWP", i32 0, i32 0), i8*** [[A_P2_PTR]], align 8
 
@@ -219,10 +219,10 @@ public func double_concrete_concrete() {
 // CHECK-NEXT:    br i1 [[IS_NULL]], label %cacheIsNull, label %cont
 
 // CHECK:       cacheIsNull:
-// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s42conditional_conformance_basic_conformances6DoubleVyAA4IsP2VAA0F2P3VGMa"(i64 0)
+// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s42conditional_conformance_basic_conformances6DoubleVyAA4IsP2VAA0F2P3VGMa"(i64 255)
 // CHECK-NEXT:    [[Double_TYPE:%.*]] = extractvalue %swift.metadata_response [[T0]], 0
 
-// CHECK-NEXT:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [2 x i8**], [2 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
+// CHECK:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [2 x i8**], [2 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
 // CHECK-NEXT:    [[B_P2_PTR:%.*]] = getelementptr inbounds i8**, i8*** [[CONDITIONAL_REQUIREMENTS]], i32 0
 // CHECK-NEXT:    store i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @"$s42conditional_conformance_basic_conformances4IsP2VAA0F0AAWP", i32 0, i32 0), i8*** [[B_P2_PTR]], align 8
 // CHECK-NEXT:    [[C_P3_PTR:%.*]] = getelementptr inbounds i8**, i8*** [[CONDITIONAL_REQUIREMENTS]], i32 1

test/Inputs/conditional_conformance_subclass.swift

@@ -83,9 +83,9 @@ public func subclassgeneric_concrete() {
 // CHECK-NEXT:    br i1 [[IS_NULL]], label %cacheIsNull, label %cont
 
 // CHECK:       cacheIsNull:
-// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s32conditional_conformance_subclass15SubclassGenericCyAA4IsP2VGMa"(i64 0)
+// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s32conditional_conformance_subclass15SubclassGenericCyAA4IsP2VGMa"(i64 255)
 // CHECK-NEXT:    [[SubclassGeneric_TYPE:%.*]] = extractvalue %swift.metadata_response [[T0]], 0
-// CHECK-NEXT:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [1 x i8**], [1 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
+// CHECK:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [1 x i8**], [1 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
 // CHECK-NEXT:    [[A_P2_PTR:%.*]] = getelementptr inbounds i8**, i8*** [[CONDITIONAL_REQUIREMENTS]], i32 0
 // CHECK-NEXT:    store i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @"$s32conditional_conformance_subclass4IsP2VAA0E0AAWP", i32 0, i32 0), i8*** [[A_P2_PTR]], align 8
 // CHECK-NEXT:    [[Base_P1:%.*]] = call i8** @swift_getWitnessTable
@@ -118,9 +118,9 @@ public func subclassconcrete() {
 // CHECK-NEXT:    br i1 [[IS_NULL]], label %cacheIsNull, label %cont
 
 // CHECK:       cacheIsNull:
-// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s32conditional_conformance_subclass16SubclassConcreteCMa"(i64 0)
+// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s32conditional_conformance_subclass16SubclassConcreteCMa"(i64 255)
 // CHECK-NEXT:    [[SubclassConcrete_TYPE:%.*]] = extractvalue %swift.metadata_response [[T0]], 0
-// CHECK-NEXT:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [1 x i8**], [1 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
+// CHECK:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [1 x i8**], [1 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
 // CHECK-NEXT:    [[A_P2_PTR:%.*]] = getelementptr inbounds i8**, i8*** [[CONDITIONAL_REQUIREMENTS]], i32 0
 // CHECK-NEXT:    store i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @"$s32conditional_conformance_subclass4IsP2VAA0E0AAWP", i32 0, i32 0), i8*** [[A_P2_PTR]], align 8
 // CHECK-NEXT:    [[Base_P1:%.*]] = call i8** @swift_getWitnessTable
@@ -153,9 +153,9 @@ public func subclassgenericconcrete() {
 // CHECK-NEXT:    br i1 [[IS_NULL]], label %cacheIsNull, label %cont
 
 // CHECK:       cacheIsNull:
-// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s32conditional_conformance_subclass23SubclassGenericConcreteCMa"(i64 0)
+// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s32conditional_conformance_subclass23SubclassGenericConcreteCMa"(i64 255)
 // CHECK-NEXT:    [[SubclassGenericConcrete_TYPE:%.*]] = extractvalue %swift.metadata_response [[T0]], 0
-// CHECK-NEXT:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [1 x i8**], [1 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
+// CHECK:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [1 x i8**], [1 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
 // CHECK-NEXT:    [[A_P2_PTR:%.*]] = getelementptr inbounds i8**, i8*** [[CONDITIONAL_REQUIREMENTS]], i32 0
 // CHECK-NEXT:    store i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @"$s32conditional_conformance_subclass4IsP2VAA0E0AAWP", i32 0, i32 0), i8*** [[A_P2_PTR]], align 8
 // CHECK-NEXT:    [[Base_P1:%.*]] = call i8** @swift_getWitnessTable

test/Inputs/conditional_conformance_with_assoc.swift

@@ -200,9 +200,9 @@ public func concrete_concrete() {
 // CHECK-NEXT:    br i1 [[IS_NULL]], label %cacheIsNull, label %cont
 
 // CHECK:       cacheIsNull:
-// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s34conditional_conformance_with_assoc6DoubleVyAA8IsAlsoP2VAA0F2P3VGMa"(i64 0)
+// CHECK-NEXT:    [[T0:%.*]] = call swiftcc %swift.metadata_response @"$s34conditional_conformance_with_assoc6DoubleVyAA8IsAlsoP2VAA0F2P3VGMa"(i64 255)
 // CHECK-NEXT:    [[Double_TYPE:%.*]] = extractvalue %swift.metadata_response [[T0]], 0
-// CHECK-NEXT:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [3 x i8**], [3 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
+// CHECK:    [[CONDITIONAL_REQUIREMENTS:%.*]] = getelementptr inbounds [3 x i8**], [3 x i8**]* %conditional.requirement.buffer, i32 0, i32 0
 // CHECK-NEXT:    [[C_P3_PTR:%.*]] = getelementptr inbounds i8**, i8*** [[CONDITIONAL_REQUIREMENTS]], i32 0
 // CHECK-NEXT:    store i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @"$s34conditional_conformance_with_assoc4IsP3VAA0F0AAWP", i32 0, i32 0), i8*** [[C_P3_PTR]], align 8
 // CHECK-NEXT:    [[B_AT2_P2_PTR:%.*]] = getelementptr inbounds i8**, i8*** [[CONDITIONAL_REQUIREMENTS]], i32 1

test/Runtime/lazy_witness_table_cycle.swift

@@ -0,0 +1,31 @@
+// RUN: %target-run-simple-swift
+// REQUIRES: executable_test
+// REQUIRES: objc_interop
+
+// SR-5958
+import Foundation
+
+public struct Property: Equatable, Hashable, Codable {
+    public var value: PropertyValue<Property>
+}
+
+public enum PropertyValue<P>: Equatable, Hashable where P: Equatable & Hashable {
+    case invalid
+    case date(date: Date?)
+}
+
+extension PropertyValue: Codable where P: Codable {
+    public func encode(to encoder: Encoder) throws {}
+    public init(from decoder: Decoder) throws { self = .invalid }
+}
+
+extension String: Error {}
+
+let encoder = JSONEncoder()
+let json = try! encoder.encode(
+  Property(value: .invalid)
+)
+
+let decoder = JSONDecoder()
+let result = try! decoder.decode(Property.self, from: json)
+print(result)