SILGen: Force lazy conformances referenced from various places in the AST

SILGen has the ability to lazily emit ClangImporter-synthesized
conformances. Sema builds a per-SourceFile list of "used" conformances,
which are forced to be emitted by SILGen. All other conformances can be
emitted lazily.

Some of these "used" conformances are in fact not referenced by SILGen
at all, but must exist for emission by IRGen so that they can be
referenced from type metadata accessors, as well as available at
runtime for the dynamic cast machinery.

To handle these cases, add an AST walk to SILGen which emits the types
of stored properties, the superclass of a class, and a few other
things that might not be referenced directly from SIL.

For now, this is all redundant because Sema forces the right
conformances anyway, but that's going to change soon.

Author: slavapestov

lib/SILGen/SILGen.h

@@ -431,6 +431,10 @@ class LLVM_LIBRARY_VISIBILITY SILGenModule : public ASTVisitor<SILGenModule> {
   /// Emit all lazy conformances referenced from this function body.
   void emitLazyConformancesForFunction(SILFunction *F);
 
+  /// Emit all lazy conformances referenced from this type's signature and
+  /// stored properties (or in the case of enums, associated values).
+  void emitLazyConformancesForType(NominalTypeDecl *NTD);
+
   /// Mark a protocol conformance as used, so we know we need to emit it if
   /// it's in our TU.
   void useConformance(ProtocolConformanceRef conformance);

lib/SILGen/SILGenLazyConformance.cpp

@@ -249,4 +249,42 @@ void SILGenModule::emitLazyConformancesForFunction(SILFunction *F) {
   for (auto &BB : *F)
     for (auto &I : BB)
       emitter.visit(&I);
+}
+
+void SILGenModule::emitLazyConformancesForType(NominalTypeDecl *NTD) {
+  auto *genericSig = NTD->getGenericSignature();
+
+  if (genericSig) {
+    for (auto reqt : genericSig->getRequirements()) {
+      if (reqt.getKind() != RequirementKind::Layout)
+        useConformancesFromType(reqt.getSecondType()->getCanonicalType());
+    }
+  }
+
+  if (auto *ED = dyn_cast<EnumDecl>(NTD)) {
+    for (auto *EED : ED->getAllElements()) {
+      if (EED->hasAssociatedValues()) {
+        useConformancesFromType(EED->getArgumentInterfaceType()
+                                   ->getCanonicalType(genericSig));
+      }
+    }
+  }
+
+  if (isa<StructDecl>(NTD) || isa<ClassDecl>(NTD)) {
+    for (auto *VD : NTD->getStoredProperties()) {
+      useConformancesFromType(VD->getValueInterfaceType()
+                                ->getCanonicalType(genericSig));
+    }
+  }
+
+  if (auto *CD = dyn_cast<ClassDecl>(NTD))
+    if (auto superclass = CD->getSuperclass())
+      useConformancesFromType(superclass->getCanonicalType(genericSig));
+
+  if (auto *PD = dyn_cast<ProtocolDecl>(NTD)) {
+    for (auto reqt : PD->getRequirementSignature()) {
+      if (reqt.getKind() != RequirementKind::Layout)
+        useConformancesFromType(reqt.getSecondType()->getCanonicalType());
+    }
+  }
 }

lib/SILGen/SILGenType.cpp

@@ -949,6 +949,8 @@ class SILGenType : public TypeMemberVisitor<SILGenType> {
 
   /// Emit SIL functions for all the members of the type.
   void emitType() {
+    SGM.emitLazyConformancesForType(theType);
+
     for (Decl *member : theType->getMembers())
       visit(member);