Eagerly emit getters at Onone.

Force SILGen to also eagerly emit getters when compiling at Onone.
The reason for this is that getters (even not user-written ones,
generated by result builders) can, and are often called by users
debugging swift programs, and should be available for that reason.

rdar://133329303

include/swift/SIL/SILDeclRef.h

@@ -576,6 +576,10 @@ struct SILDeclRef {
   /// for e.g a lazy variable getter.
   bool hasUserWrittenCode() const;
 
+  /// Returns true if this is a function that should be emitted because it is
+  /// accessible in the debugger.
+  bool shouldBeEmittedForDebugger() const;
+
   /// Return the scope in which the parent class of a method (i.e. class
   /// containing this declaration) can be subclassed, returning NotApplicable if
   /// this is not a method, there is no such class, or the class cannot be

lib/SIL/IR/SILDeclRef.cpp

@@ -387,6 +387,39 @@ bool SILDeclRef::hasUserWrittenCode() const {
   llvm_unreachable("Unhandled case in switch!");
 }
 
+bool SILDeclRef::shouldBeEmittedForDebugger() const {
+  if (!isFunc())
+    return false;
+
+  if (getASTContext().SILOpts.OptMode != OptimizationMode::NoOptimization)
+    return false;;
+
+  if (!getASTContext().SILOpts.ShouldFunctionsBePreservedToDebugger)
+    return false;
+
+  if (getASTContext().LangOpts.hasFeature(Feature::Embedded))
+    return false;
+
+  ValueDecl *decl = getDecl();
+  DeclAttributes &attrs = decl->getAttrs();
+  if (attrs.hasSemanticsAttr("no.preserve.debugger"))
+    return false;
+
+  if (getLinkage(ForDefinition) == SILLinkage::Shared)
+    return false;
+  
+  if (auto decl = getDecl()) 
+    if (!decl->isImplicit())
+      return true;
+
+  // Synthesized getters are still callable in the debugger.
+  if (auto *accessor = dyn_cast_or_null<AccessorDecl>(getFuncDecl())) {
+    return accessor->isSynthesized() && accessor->isGetterOrSetter();
+  };
+
+  return false;
+}
+
 namespace {
 enum class LinkageLimit {
   /// No limit.

lib/SILGen/SILGen.cpp

@@ -1198,8 +1198,9 @@ void SILGenModule::emitOrDelayFunction(SILDeclRef constant) {
   auto emitAfter = lastEmittedFunction;
 
   // Implicit decls may be delayed if they can't be used externally.
-  auto linkage = constant.getLinkage(ForDefinition);
+  auto linkage = constant.getLinkage(ForDefinition);;
-  bool mayDelay = !constant.hasUserWrittenCode() &&
+  bool mayDelay = !constant.shouldBeEmittedForDebugger() &&
+                  !constant.hasUserWrittenCode() &&
                   !constant.isDynamicallyReplaceable() &&
                   !isPossiblyUsedExternally(linkage, M.isWholeModule());
 

test/IRGen/preserve_for_debugger.swift

@@ -55,6 +55,8 @@ class Baz: Foo {
 
 struct Qux {
   @Bar(wrappedValue: Baz()) private var baz: Baz
+  // Baz instance that is never accessed.
+  @Bar(wrappedValue: Baz()) private var baz2: Baz
 
     func f() {
         print(self.baz) // break here
@@ -64,3 +66,4 @@ let qux = Qux()
 qux.f()
 
 // CHECK: !DISubprogram(name: "baz.get"
+// CHECK: !DISubprogram(name: "baz2.get"