SILGen: Emit accessors as part of their storage

This removes an intricate set of invariants that must be kept consistent
between Parse and SILGen. It will also make it easier to implement local
variables with 'lazy' and property wrappers in the future.

Author: slavapestov

lib/SILGen/SILGen.cpp

@@ -1316,48 +1316,17 @@ void SILGenModule::visitVarDecl(VarDecl *vd) {
   if (vd->hasStorage())
     addGlobalVariable(vd);
 
-  // Emit the variable's opaque accessors.
-  vd->visitExpectedOpaqueAccessors([&](AccessorKind kind) {
-    auto accessor = vd->getAccessor(kind);
-    if (!accessor) return;
-
-    // Only emit the accessor if it wasn't added to the surrounding decl
-    // list by the parser.  We can test that easily by looking at the impl
-    // info, since all of these accessors have a corresponding access kind
-    // whose impl should definitely point at the accessor if it was parsed.
-    //
-    // This is an unfortunate formation rule, but it's easier than messing
-    // with the invariants for now.
-    bool shouldEmit = [&] {
-      auto impl = vd->getImplInfo();
-      switch (kind) {
-      case AccessorKind::Get:
-        return impl.getReadImpl() != ReadImplKind::Get &&
-               !(impl.getReadImpl() == ReadImplKind::Stored &&
-                 impl.getWriteImpl() == WriteImplKind::StoredWithObservers);
-      case AccessorKind::Read:
-        return impl.getReadImpl() != ReadImplKind::Read;
-      case AccessorKind::Set:
-        return impl.getWriteImpl() != WriteImplKind::Set &&
-               impl.getWriteImpl() != WriteImplKind::StoredWithObservers;
-      case AccessorKind::Modify:
-        return impl.getReadWriteImpl() != ReadWriteImplKind::Modify;
-#define ACCESSOR(ID) \
-      case AccessorKind::ID:
-#define OPAQUE_ACCESSOR(ID, KEYWORD)
-#include "swift/AST/AccessorKinds.def"
-        llvm_unreachable("not an opaque accessor");
-      }
-      llvm_unreachable("covered switch");
-    }();
-    if (!shouldEmit) return;
-
+  for (auto *accessor : vd->getAllAccessors())
     emitFunction(accessor);
-  });
 
   tryEmitPropertyDescriptor(vd);
 }
 
+void SILGenModule::visitSubscriptDecl(SubscriptDecl *sd) {
+  for (auto *accessor : sd->getAllAccessors())
+    emitFunction(accessor);
+}
+
 bool
 SILGenModule::canStorageUseStoredKeyPathComponent(AbstractStorageDecl *decl,
                                                   ResilienceExpansion expansion) {

lib/SILGen/SILGen.h

@@ -188,12 +188,14 @@ class LLVM_LIBRARY_VISIBILITY SILGenModule : public ASTVisitor<SILGenModule> {
   void visitTypeAliasDecl(TypeAliasDecl *d) {}
   void visitOpaqueTypeDecl(OpaqueTypeDecl *d) {}
   void visitAbstractTypeParamDecl(AbstractTypeParamDecl *d) {}
-  void visitSubscriptDecl(SubscriptDecl *d) {}
   void visitConstructorDecl(ConstructorDecl *d) {}
   void visitDestructorDecl(DestructorDecl *d) {}
   void visitModuleDecl(ModuleDecl *d) { }
   void visitMissingMemberDecl(MissingMemberDecl *d) {}
 
+  // Emitted as part of its storage.
+  void visitAccessorDecl(AccessorDecl *ad) {}
+
   void visitFuncDecl(FuncDecl *fd);
   void visitPatternBindingDecl(PatternBindingDecl *vd);
   void visitTopLevelCodeDecl(TopLevelCodeDecl *td);
@@ -202,6 +204,7 @@ class LLVM_LIBRARY_VISIBILITY SILGenModule : public ASTVisitor<SILGenModule> {
   void visitNominalTypeDecl(NominalTypeDecl *ntd);
   void visitExtensionDecl(ExtensionDecl *ed);
   void visitVarDecl(VarDecl *vd);
+  void visitSubscriptDecl(SubscriptDecl *sd);
 
   void emitAbstractFuncDecl(AbstractFunctionDecl *AFD);
 

lib/SILGen/SILGenDecl.cpp

@@ -1192,6 +1192,10 @@ void SILGenFunction::visitPatternBindingDecl(PatternBindingDecl *PBD) {
 
 void SILGenFunction::visitVarDecl(VarDecl *D) {
   // We handle emitting the variable storage when we see the pattern binding.
+
+  // Emit the variable's accessors.
+  for (auto *accessor : D->getAllAccessors())
+    SGM.emitFunction(accessor);
 }
 
 /// Emit literals for the major, minor, and subminor components of the version

lib/SILGen/SILGenFunction.h

@@ -1787,6 +1787,9 @@ class LLVM_LIBRARY_VISIBILITY SILGenFunction
     llvm_unreachable("Not yet implemented");
   }
 
+  // Emitted as part of its storage.
+  void visitAccessorDecl(AccessorDecl *D) {}
+
   void visitFuncDecl(FuncDecl *D);
   void visitPatternBindingDecl(PatternBindingDecl *D);