From 02d8ef242da4547fc6ebce8fc4df47581206a745 Mon Sep 17 00:00:00 2001
From: Andrea Corallo <akrl@sdf.org>
Date: Thu, 7 May 2020 22:31:57 +0100
Subject: [PATCH] Move symbol value into separate binding

---
 src/alloc.c | 22 ++++++++++++----------
 src/lisp.h  | 18 +++++++++++-------
 2 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/src/alloc.c b/src/alloc.c
index 4bbc6e37649..5199238b6bf 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -3524,7 +3524,7 @@ init_symbol (Lisp_Object val, Lisp_Object name)
   set_symbol_plist (val, Qnil);
   p->u.s.redirect = SYMBOL_PLAINVAL;
   p->u.s.val.value = Qunbound;
-  set_symbol_function (val, Qnil);
+  p->u.s._function = Qnil;
   set_symbol_next (val, NULL);
   p->u.s.gcmarkbit = false;
   p->u.s.interned = SYMBOL_UNINTERNED;
@@ -4510,7 +4510,7 @@ live_symbol_holding (struct mem_node *m, void *p)
 	{
 	  cp = ptr_bounds_copy (cp, b);
 	  struct Lisp_Symbol *s = p = cp -= offset % sizeof b->symbols[0];
-	  if (!deadp (SYMBOL_FUNCTION (s)))
+	  if (!deadp (s->u.s._function))
 	    return make_lisp_symbol (s);
 	}
     }
@@ -6647,8 +6647,8 @@ mark_object (Lisp_Object arg)
         CHECK_ALLOCATED_AND_LIVE_SYMBOL ();
         set_symbol_marked(ptr);
 	/* Attempt to catch bogus objects.  */
-	eassert (valid_lisp_object_p (SYMBOL_FUNCTION (ptr)));
-	mark_object (SYMBOL_FUNCTION (ptr));
+	eassert (valid_lisp_object_p (ptr->u.s._function));
+	mark_object (ptr->u.s._function);
 	mark_object (ptr->u.s.plist);
 	switch (ptr->u.s.redirect)
 	  {
@@ -7005,7 +7005,9 @@ sweep_symbols (void)
               sym->u.s.next = symbol_free_list;
               symbol_free_list = sym;
 	      /* FIXME */
-              symbol_free_list->u.s._function = dead_object ();
+	      if (!NILP (sym->u.s._function))
+		XBINDING (symbol_free_list->u.s._function)->b[curr_lexspace] =
+		  dead_object ();
               ++this_free;
             }
           else
@@ -7013,7 +7015,7 @@ sweep_symbols (void)
               ++num_used;
               sym->u.s.gcmarkbit = 0;
               /* Attempt to catch bogus objects.  */
-              eassert (valid_lisp_object_p (SYMBOL_FUNCTION (sym)));
+              eassert (valid_lisp_object_p (sym->u.s._function));
             }
         }
 
@@ -7167,10 +7169,10 @@ symbol_uses_obj (Lisp_Object symbol, Lisp_Object obj)
   struct Lisp_Symbol *sym = XSYMBOL (symbol);
   Lisp_Object val = find_symbol_value (symbol);
   return (EQ (val, obj)
-	  || EQ (SYMBOL_FUNCTION (sym), obj)
-	  || (!NILP (SYMBOL_FUNCTION (sym))
-	      && COMPILEDP (SYMBOL_FUNCTION (sym))
-	      && EQ (AREF (SYMBOL_FUNCTION (sym), COMPILED_BYTECODE), obj))
+	  || EQ (sym->u.s._function, obj)
+	  || (!NILP (sym->u.s._function)
+	      && COMPILEDP (sym->u.s._function)
+	      && EQ (AREF (sym->u.s._function, COMPILED_BYTECODE), obj))
 	  || (!NILP (val)
 	      && COMPILEDP (val)
 	      && EQ (AREF (val, COMPILED_BYTECODE), obj)));
diff --git a/src/lisp.h b/src/lisp.h
index 7bf822253ac..29df243c0aa 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2171,7 +2171,7 @@ typedef jmp_buf sys_jmp_buf;
 
 extern EMACS_INT curr_lexspace;
 
-INLINE Lisp_Object make_binding (void);
+INLINE Lisp_Object make_binding (Lisp_Object);
 
 struct Lisp_Binding
 {
@@ -2219,7 +2219,9 @@ SYMBOL_VAL (struct Lisp_Symbol *sym)
 INLINE Lisp_Object
 SYMBOL_FUNCTION (struct Lisp_Symbol *sym)
 {
-  return sym->u.s._function;
+  if (!NILP (sym->u.s._function))
+    return XBINDING (sym->u.s._function)->b[curr_lexspace];
+  return Qnil;
 }
 
 INLINE struct Lisp_Symbol *
@@ -2247,7 +2249,7 @@ SET_SYMBOL_VAL (struct Lisp_Symbol *sym, Lisp_Object v)
 {
   eassert (sym->u.s.redirect == SYMBOL_PLAINVAL);
   if (EQ (sym->u.s.val.value, Qunbound))
-    sym->u.s.val.value = make_binding ();
+    sym->u.s.val.value = make_binding (Qunbound);
   struct Lisp_Binding *binding = XBINDING (sym->u.s.val.value);
   binding->b[curr_lexspace] = v;
 }
@@ -3429,8 +3431,10 @@ set_hash_value_slot (struct Lisp_Hash_Table *h, ptrdiff_t idx, Lisp_Object val)
 INLINE void
 set_symbol_function (Lisp_Object sym, Lisp_Object function)
 {
-  /* FIXME */
-  XSYMBOL (sym)->u.s._function = function;
+  struct Lisp_Symbol *s = XSYMBOL (sym);
+  if (NILP (s->u.s._function))
+    s->u.s._function = make_binding (Qnil);
+  XBINDING (s->u.s._function)->b[curr_lexspace] = function;
 }
 
 INLINE void
@@ -5086,13 +5090,13 @@ maybe_gc (void)
 }
 
 INLINE Lisp_Object
-make_binding (void)
+make_binding (Lisp_Object init_val)
 {
   struct Lisp_Binding *binding =
     ALLOCATE_ZEROED_PSEUDOVECTOR (struct Lisp_Binding,
 				  b[MAX_LEXSPACES - 1], PVEC_BINDING);
   for (EMACS_INT i = 0; i < MAX_LEXSPACES; i++)
-    binding->b[i] = Qunbound;
+    binding->b[i] = init_val;
   return make_lisp_ptr (binding, Lisp_Vectorlike);
 }
 
-- 
2.39.5