A SILModule Always Has An Associated Context

Now that the integrated REPL has been removed,
there is always an associated decl context, and
we can assert as such.

Author: hamishknight

include/swift/SIL/SILModule.h

@@ -366,15 +366,15 @@ class SILModule {
   ASTContext &getASTContext() const;
   SourceManager &getSourceManager() const { return getASTContext().SourceMgr; }
 
-  /// Get the Swift DeclContext associated with this SIL module.
+  /// Get the Swift DeclContext associated with this SIL module. This is never
+  /// null.
   ///
   /// All AST declarations within this context are assumed to have been fully
   /// processed as part of generating this module. This allows certain passes
   /// to make additional assumptions about these declarations.
   ///
   /// If this is the same as TheSwiftModule, the entire module is being
-  /// compiled as a single unit. If this is null, no context-based assumptions
-  /// can be made.
+  /// compiled as a single unit.
   const DeclContext *getAssociatedContext() const {
     return AssociatedDeclContext;
   }

lib/IRGen/IRGenModule.cpp

@@ -1203,14 +1203,9 @@ static bool isFirstObjectFileInModule(IRGenModule &IGM) {
   if (IGM.getSILModule().isWholeModule())
     return IGM.IRGen.getPrimaryIGM() == &IGM;
 
-  const DeclContext *DC = IGM.getSILModule().getAssociatedContext();
-  if (!DC)
-    return false;
-
-  assert(!isa<ModuleDecl>(DC) && "that would be a whole module build");
-  assert(isa<FileUnit>(DC) && "compiling something smaller than a file?");
-  ModuleDecl *containingModule = cast<FileUnit>(DC)->getParentModule();
-  return containingModule->getFiles().front() == DC;
+  auto *file = cast<FileUnit>(IGM.getSILModule().getAssociatedContext());
+  auto *containingModule = file->getParentModule();
+  return containingModule->getFiles().front() == file;
 }
 
 void IRGenModule::emitAutolinkInfo() {

lib/SIL/IR/SIL.cpp

@@ -127,12 +127,6 @@ bool SILModule::isTypeMetadataAccessible(CanType type) {
     // Private declarations are inaccessible from different files unless
     // this is WMO and we're in the same module.
     case FormalLinkage::Private: {
-      // The only time we don't have an associated DC is in the
-      // integrated REPL, where we also don't have a concept of other
-      // source files within the current module.
-      if (!AssociatedDeclContext)
-        return (decl->getModuleContext() != getSwiftModule());
-
       // The associated DC should be either a SourceFile or, in WMO mode,
       // a ModuleDecl.  In the WMO modes, IRGen will ensure that private
       // declarations are usable throughout the module.  Therefore, in

lib/SIL/IR/SILModule.cpp

@@ -99,6 +99,8 @@ SILModule::SILModule(ModuleDecl *SwiftModule, TypeConverter &TC,
       AssociatedDeclContext(associatedDC),
       Stage(SILStage::Raw), wholeModule(wholeModule), Options(Options),
       serialized(false), SerializeSILAction(), Types(TC) {
+  assert(AssociatedDeclContext);
+
   // We always add the base SILModule serialization callback.
   std::unique_ptr<DeserializationNotificationHandler> callback(
       new SILModule::SerializationCallback());

lib/SILGen/SILGenExpr.cpp

@@ -4099,8 +4099,6 @@ static bool isVerbatimNullableTypeInC(SILModule &M, Type ty) {
 
   // Other types like UnsafePointer can also be nullable.
   const DeclContext *DC = M.getAssociatedContext();
-  if (!DC)
-    DC = M.getSwiftModule();
   ty = OptionalType::get(ty);
   return ty->isTriviallyRepresentableIn(ForeignLanguage::C, DC);
 }

lib/SILOptimizer/Transforms/SpeculativeDevirtualizer.cpp

@@ -285,8 +285,6 @@ static bool isDefaultCaseKnown(ClassHierarchyAnalysis *CHA,
   auto *Method = CMI->getMember().getAbstractFunctionDecl();
   assert(Method && "not a function");
 
-  const DeclContext *DC = AI.getModule().getAssociatedContext();
-
   if (CD->isFinal())
     return true;
 
@@ -295,13 +293,8 @@ static bool isDefaultCaseKnown(ClassHierarchyAnalysis *CHA,
   if (CD->checkAncestry(AncestryFlags::ObjC))
     return false;
 
-  // Without an associated context we cannot perform any
-  // access-based optimizations.
-  if (!DC)
-    return false;
-
   // Only handle classes defined within the SILModule's associated context.
-  if (!CD->isChildContextOf(DC))
+  if (!CD->isChildContextOf(AI.getModule().getAssociatedContext()))
     return false;
 
   if (!CD->hasAccess())

lib/SILOptimizer/Utils/Devirtualize.cpp

@@ -89,13 +89,6 @@ static bool isEffectivelyFinalMethod(FullApplySite applySite, CanType classType,
   if (cd && cd->isFinal())
     return true;
 
-  const DeclContext *dc = applySite.getModule().getAssociatedContext();
-
-  // Without an associated context we cannot perform any
-  // access-based optimizations.
-  if (!dc)
-    return false;
-
   auto *cmi = cast<MethodInst>(applySite.getCallee());
 
   if (!calleesAreStaticallyKnowable(applySite.getModule(), cmi->getMember()))
@@ -149,18 +142,11 @@ static bool isEffectivelyFinalMethod(FullApplySite applySite, CanType classType,
 ///   it is a whole-module compilation.
 static bool isKnownFinalClass(ClassDecl *cd, SILModule &module,
                               ClassHierarchyAnalysis *cha) {
-  const DeclContext *dc = module.getAssociatedContext();
-
   if (cd->isFinal())
     return true;
 
-  // Without an associated context we cannot perform any
-  // access-based optimizations.
-  if (!dc)
-    return false;
-
   // Only handle classes defined within the SILModule's associated context.
-  if (!cd->isChildContextOf(dc))
+  if (!cd->isChildContextOf(module.getAssociatedContext()))
     return false;
 
   if (!cd->hasAccess())

lib/SILOptimizer/Utils/InstOptUtils.cpp

@@ -1815,12 +1815,8 @@ bool swift::calleesAreStaticallyKnowable(SILModule &module, SILDeclRef decl) {
 /// knowable based on the Decl and the compilation mode?
 bool swift::calleesAreStaticallyKnowable(SILModule &module,
                                          AbstractFunctionDecl *afd) {
-  const DeclContext *assocDC = module.getAssociatedContext();
-  if (!assocDC)
-    return false;
-
   // Only handle members defined within the SILModule's associated context.
-  if (!afd->isChildContextOf(assocDC))
+  if (!afd->isChildContextOf(module.getAssociatedContext()))
     return false;
 
   if (afd->isDynamic()) {
@@ -1859,12 +1855,8 @@ bool swift::calleesAreStaticallyKnowable(SILModule &module,
 // FIXME: Merge this with calleesAreStaticallyKnowable above
 bool swift::calleesAreStaticallyKnowable(SILModule &module,
                                          EnumElementDecl *eed) {
-  const DeclContext *assocDC = module.getAssociatedContext();
-  if (!assocDC)
-    return false;
-
   // Only handle members defined within the SILModule's associated context.
-  if (!eed->isChildContextOf(assocDC))
+  if (!eed->isChildContextOf(module.getAssociatedContext()))
     return false;
 
   if (eed->isDynamic()) {

lib/Serialization/SerializeSIL.cpp

@@ -2645,9 +2645,6 @@ void SILSerializer::writeSILBlock(const SILModule *SILMod) {
   // Go through all SILVTables in SILMod and write them if we should
   // serialize everything.
   // FIXME: Resilience: could write out vtable for fragile classes.
-  const DeclContext *assocDC = SILMod->getAssociatedContext();
-  assert(assocDC && "cannot serialize SIL without an associated DeclContext");
-  (void)assocDC;
   for (const SILVTable &vt : SILMod->getVTables()) {
     if ((ShouldSerializeAll || vt.isSerialized()) &&
         SILMod->shouldSerializeEntitiesAssociatedWithDeclContext(vt.getClass()))