Remove legacy special return mechanism

In turn making the new one temporarily public, since a Rakudo extop
relies upon it.

src/core/callstack.h

@@ -380,7 +380,7 @@ MVMCallStackHeapFrame * MVM_callstack_allocate_heap_frame(MVMThreadContext *tc,
         MVMuint32 work_size);
 MVMint32 MVM_callstack_ensure_work_and_env_space(MVMThreadContext *tc, MVMuint32 needed_work,
         MVMuint32 needed_env);
-void * MVM_callstack_allocate_special_return(MVMThreadContext *tc,
+MVM_PUBLIC void * MVM_callstack_allocate_special_return(MVMThreadContext *tc,
         MVMSpecialReturn special_return, MVMSpecialReturn special_unwind,
         MVMSpecialReturnMark mark_data, size_t data_size);
 MVMCallStackDispatchRecord * MVM_callstack_allocate_dispatch_record(MVMThreadContext *tc);

src/core/frame.c

@@ -903,32 +903,6 @@ static MVMuint64 remove_one_frame(MVMThreadContext *tc, MVMuint8 unwind) {
 
     /* Switch back to the caller frame if there is one. */
     if (caller && (returner != tc->thread_entry_frame || tc->nested_interpreter)) {
-        /* Handle any special return hooks. */
-        if (caller->extra) {
-            MVMFrameExtra *e = caller->extra;
-            if (e->special_return || e->special_unwind) {
-                MVMSpecialReturn  sr  = e->special_return;
-                MVMSpecialReturn  su  = e->special_unwind;
-                void             *srd = e->special_return_data;
-                e->special_return           = NULL;
-                e->special_unwind           = NULL;
-                e->special_return_data      = NULL;
-                e->mark_special_return_data = NULL;
-                if (unwind && su)
-                    su(tc, srd);
-                else if (!unwind && sr)
-                    sr(tc, srd);
-                /* The special_return or special_unwind handler may schedule a
-                   finalizer call for the current runloop. If we are already in
-                   the top most call frame of the runloop, we need to replace
-                   the thread_entry_frame with the finalizer call. Otherwise we
-                   won't run the special code for ending the runloop when the
-                   finalizer returns. */
-                if (returner == tc->thread_entry_frame && tc->cur_frame != caller)
-                    tc->thread_entry_frame = tc->cur_frame;
-            }
-        }
-
         if (returner == tc->thread_entry_frame && tc->cur_frame == caller) {
             tc->cur_frame = NULL;
             return 0;
@@ -1757,19 +1731,6 @@ MVMFrameExtra * MVM_frame_extra(MVMThreadContext *tc, MVMFrame *f) {
     return f->extra;
 }
 
-/* Set up special return data on a frame. */
-void MVM_frame_special_return(MVMThreadContext *tc, MVMFrame *f,
-                               MVMSpecialReturn special_return,
-                               MVMSpecialReturn special_unwind,
-                               void *special_return_data,
-                               MVMSpecialReturnDataMark mark_special_return_data) {
-    MVMFrameExtra *e = MVM_frame_extra(tc, f);
-    e->special_return = special_return;
-    e->special_unwind = special_unwind;
-    e->special_return_data = special_return_data;
-    e->mark_special_return_data = mark_special_return_data;
-}
-
 /* Gets the code object of the caller, provided there is one. Works even in
  * the face that the caller was an inline (however, the current frame that is
  * using the op must not be itself inlined). */

src/core/frame.h

@@ -13,8 +13,6 @@
 typedef void (* MVMSpecialReturn)(MVMThreadContext *tc, void *data);
 
 /* Function pointer for marking the special return handler data. */
-typedef void (* MVMSpecialReturnDataMark)(MVMThreadContext *tc, MVMFrame *frame,
-                                          MVMGCWorklist *worklist); /* XXX Legacy */
 typedef void (* MVMSpecialReturnMark)(MVMThreadContext *tc, void *data,
                                       MVMGCWorklist *worklist);
 
@@ -96,20 +94,6 @@ struct MVMFrame {
 /* Extra data that a handful of call frames optionally need. It is needed
  * only while the frame is in dynamic scope; after that it can go away. */
 struct MVMFrameExtra {
-    /* If we want to invoke a special handler upon a return to this
-     * frame, this function pointer is set. */
-    MVMSpecialReturn special_return;
-
-    /* If we want to invoke a special handler upon unwinding past a
-     * frame, this function pointer is set. */
-    MVMSpecialReturn special_unwind;
-
-    /* Data slot for the special return handler function. */
-    void *special_return_data;
-
-    /* Flag for if special_return_data need to be GC marked. */
-    MVMSpecialReturnDataMark mark_special_return_data;
-
     /* Cache for dynlex lookup; if the name is non-null, the cache is valid
      * and the register can be accessed directly to find the contextual. */
     MVMString   *dynlex_cache_name;
@@ -199,7 +183,4 @@ MVM_PUBLIC MVMRegister * MVM_frame_try_get_lexical(MVMThreadContext *tc, MVMFram
 MVMuint16 MVM_frame_translate_to_primspec(MVMThreadContext *tc, MVMuint16 kind);
 MVMuint16 MVM_frame_lexical_primspec(MVMThreadContext *tc, MVMFrame *f, MVMString *name);
 MVMFrameExtra * MVM_frame_extra(MVMThreadContext *tc, MVMFrame *f);
-MVM_PUBLIC void MVM_frame_special_return(MVMThreadContext *tc, MVMFrame *f,
-    MVMSpecialReturn special_return, MVMSpecialReturn special_unwind,
-    void *special_return_data, MVMSpecialReturnDataMark mark_special_return_data);
 MVMObject * MVM_frame_caller_code(MVMThreadContext *tc);

src/gc/roots.c

@@ -420,8 +420,6 @@ void MVM_gc_root_add_frame_roots_to_worklist(MVMThreadContext *tc, MVMGCWorklist
     /* Mark frame extras if needed. */
     if (cur_frame->extra) {
         MVMFrameExtra *e = cur_frame->extra;
-        if (e->special_return_data && e->mark_special_return_data)
-            e->mark_special_return_data(tc, cur_frame, worklist);
         if (e->dynlex_cache_name)
             MVM_gc_worklist_add(tc, worklist, &e->dynlex_cache_name);
         MVM_gc_worklist_add(tc, worklist, &e->exit_handler_result);

src/profiler/heapsnapshot.c

@@ -614,10 +614,6 @@ static void process_workitems(MVMThreadContext *tc, MVMHeapSnapshotState *ss) {
 
                 if (frame->extra) {
                     MVMFrameExtra *e = frame->extra;
-                    if (e->special_return_data && e->mark_special_return_data) {
-                        e->mark_special_return_data(tc, frame, ss->gcwl);
-                        process_gc_worklist(tc, ss, "Special return data");
-                    }
                     MVM_profile_heap_add_collectable_rel_const_cstr(tc, ss,
                         (MVMCollectable *)e->dynlex_cache_name,
                         "Dynamic lexical cache name");