IRGen: Some progress toward tuple conformances

Author: slavapestov

include/swift/SIL/SILWitnessTable.h

@@ -238,12 +238,8 @@ class SILWitnessTable : public llvm::ilist_node<SILWitnessTable>,
   /// Return the protocol for which this witness table is a conformance.
   ProtocolDecl *getProtocol() const;
 
-  /// Return the formal type which conforms to the protocol.
-  ///
-  /// Note that this will not be a substituted type: it may only be meaningful
-  /// in the abstract context of the conformance rather than the context of any
-  /// particular use of it.
-  CanType getConformingType() const;
+  /// Return the nominal type declaration which conforms to the protocol.
+  NominalTypeDecl *getConformingNominal() const;
 
   /// Return the symbol name of the witness table that will be propagated to the
   /// object file level.

lib/IRGen/GenDecl.cpp

@@ -4080,8 +4080,8 @@ void IRGenModule::appendLLVMUsedConditionalEntry(
   auto *protocol = getAddrOfProtocolDescriptor(conformance->getProtocol())
                        ->stripPointerCasts();
   auto *type = getAddrOfTypeContextDescriptor(
-                   conformance->getType()->getAnyNominal(), DontRequireMetadata)
-                   ->stripPointerCasts();
+                   conformance->getDeclContext()->getSelfNominalTypeDecl(),
+                   DontRequireMetadata)->stripPointerCasts();
 
   llvm::Metadata *metadata[] = {
       // (1) which variable is being conditionalized, "target"

lib/IRGen/GenProto.cpp

@@ -1984,7 +1984,7 @@ namespace {
       // Add a relative reference to the type, with the type reference
       // kind stored in the flags.
       auto ref = IGM.getTypeEntityReference(
-                   Conformance->getType()->getAnyNominal());
+                   Conformance->getDeclContext()->getSelfNominalTypeDecl());
       B.addRelativeAddress(ref.getValue());
       Flags = Flags.withTypeReferenceKind(ref.getKind());
     }
@@ -2474,8 +2474,9 @@ void IRGenModule::emitSILWitnessTable(SILWitnessTable *wt) {
   // Record this conformance descriptor.
   addProtocolConformance(std::move(description));
 
-  IRGen.noteUseOfTypeContextDescriptor(conf->getType()->getAnyNominal(),
-                                       RequireMetadata);
+  IRGen.noteUseOfTypeContextDescriptor(
+      conf->getDeclContext()->getSelfNominalTypeDecl(),
+      RequireMetadata);
 }
 
 /// True if a function's signature in LLVM carries polymorphic parameters.

lib/IRGen/IRGenModule.cpp

@@ -1284,10 +1284,7 @@ bool IRGenerator::canEmitWitnessTableLazily(SILWitnessTable *wt) {
   if (wt->getLinkage() == SILLinkage::Shared)
     return true;
 
-  NominalTypeDecl *ConformingTy =
-    wt->getConformingType()->getNominalOrBoundGenericNominal();
-
-  switch (ConformingTy->getEffectiveAccess()) {
+  switch (wt->getConformingNominal()->getEffectiveAccess()) {
     case AccessLevel::Private:
     case AccessLevel::FilePrivate:
       return true;

lib/IRGen/Linking.cpp

@@ -803,15 +803,15 @@ SILLinkage LinkEntity::getLinkage(ForDefinition_t forDefinition) const {
 
   case Kind::ProtocolWitnessTableLazyAccessFunction:
   case Kind::ProtocolWitnessTableLazyCacheVariable: {
-    auto ty = getType();
-    ValueDecl *nominal = nullptr;
-    if (auto *otat = ty->getAs<OpaqueTypeArchetypeType>()) {
-      nominal = otat->getDecl();
+    TypeDecl *typeDecl = nullptr;
+    if (auto *otat = getType()->getAs<OpaqueTypeArchetypeType>()) {
+      typeDecl = otat->getDecl();
     } else {
-      nominal = ty->getAnyNominal();
+      typeDecl = getProtocolConformance()->getDeclContext()
+          ->getSelfNominalTypeDecl();
     }
-    assert(nominal);
-    if (getDeclLinkage(nominal) == FormalLinkage::Private ||
+    assert(typeDecl);
+    if (getDeclLinkage(typeDecl) == FormalLinkage::Private ||
         getLinkageAsConformance() == SILLinkage::Private) {
       return SILLinkage::Private;
     } else {

lib/SIL/IR/SILWitnessTable.cpp

@@ -43,8 +43,8 @@ ProtocolDecl *SILWitnessTable::getProtocol() const {
   return getConformance()->getProtocol();
 }
 
-CanType SILWitnessTable::getConformingType() const {
-  return getConformance()->getType()->getCanonicalType();
+NominalTypeDecl *SILWitnessTable::getConformingNominal() const {
+  return getConformance()->getDeclContext()->getSelfNominalTypeDecl();
 }
 
 void SILWitnessTable::addWitnessTable() {

test/IRGen/tuple_conformances.swift

@@ -0,0 +1,34 @@
+// RUN: %target-swift-frontend -emit-ir -parse-stdlib -primary-file %s -enable-experimental-feature TupleConformances -parse-as-library | %FileCheck %s
+
+import Swift
+
+protocol P {
+  func f()
+}
+
+extension P {
+  func f() {}
+}
+
+extension Builtin.TheTupleType: P where repeat each Elements: P {
+}
+
+func takesP<T: P>(_ t: T) {
+  t.f()
+}
+
+struct S: P {}
+
+func use() {
+  takesP((S(), S()))
+}
+
+// CHECK-LABEL: define internal swiftcc void @"$sxxQp_t18tuple_conformances1PA2aBP1fyyFTW"({{i32|i64}} %0, ptr %"{{.*}}", ptr {{.*}} swiftself %1, ptr %Self, ptr %SelfWitnessTable) {{.*}} {
+
+// CHECK-LABEL: define hidden swiftcc void @"$s18tuple_conformances3useyyF"() {{.*}} {
+// CHECK: call ptr @"$s18tuple_conformances1SV_ACtxxQp_tAA1PAAWl"()
+// CHECK: ret void
+
+// CHECK-LABEL: define linkonce_odr hidden ptr @"$s18tuple_conformances1SV_ACtxxQp_tAA1PAAWl"() {{.*}} {
+
+