[Emacs-diffs] master f8ad6b3 09/10: New type Lisp_Misc_Ptr

[Paul Eggert]

branch: master
commit f8ad6b311bf142defe4c203b64713c5a5051c4a7
Author: Paul Eggert <address@hidden>
Commit: Paul Eggert <address@hidden>

    New type Lisp_Misc_Ptr
    
    This is a streamlined version of Lisp_Save_Value, which contains just
    a pointer, as that is all Lisp_Save_Values are used for any more.
    With the previous changes, these objects are not primarily used as
    save values, so just call them "Misc" rather than "Save".
    * src/alloc.c (make_misc_ptr): New function.
    (mark_object): Mark Lisp_Misc_Ptr too.
    * src/lisp.h (Lisp_Misc_Ptr): New constant.
    (struct Lisp_Misc_Ptr): New type.
    (make_mint_ptr, mint_ptrp, xmint_pointer):
    Use Lisp_Misc_Ptr, not Lisp_Save_Value.
    (union Lisp_Misc): Add Lisp_Misc_Ptr.
    * src/print.c (print_object): Print Lisp_Misc_Ptr.
---
 src/alloc.c   | 12 ++++++++++++
 src/font.h    |  2 +-
 src/lisp.h    | 29 ++++++++++++++++++++---------
 src/print.c   |  7 +++++++
 src/w32font.c |  2 +-
 5 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/src/alloc.c b/src/alloc.c
index 1d3ec4f..6b57c83 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -3827,6 +3827,14 @@ free_save_value (Lisp_Object save)
   free_misc (save);
 }
 
+Lisp_Object
+make_misc_ptr (void *a)
+{
+  Lisp_Object val = allocate_misc (Lisp_Misc_Ptr);
+  XUNTAG (val, Lisp_Misc, struct Lisp_Misc_Ptr)->pointer = a;
+  return val;
+}
+
 /* Return a Lisp_Misc_Overlay object with specified START, END and PLIST.  */
 
 Lisp_Object
@@ -6692,6 +6700,10 @@ mark_object (Lisp_Object arg)
          mark_save_value (XSAVE_VALUE (obj));
          break;
 
+       case Lisp_Misc_Ptr:
+         XMISCANY (obj)->gcmarkbit = true;
+         break;
+
        case Lisp_Misc_Overlay:
          mark_overlay (XOVERLAY (obj));
           break;
diff --git a/src/font.h b/src/font.h
index 6ec32de..e84c6f3 100644
--- a/src/font.h
+++ b/src/font.h
@@ -613,7 +613,7 @@ struct font_driver
      (symbols).  */
   Lisp_Object (*list_family) (struct frame *f);
 
-  /* Optional (if FONT_EXTRA_INDEX is not Lisp_Save_Value).
+  /* Optional.
      Free FONT_EXTRA_INDEX field of FONT_ENTITY.  */
   void (*free_entity) (Lisp_Object font_entity);
 
diff --git a/src/lisp.h b/src/lisp.h
index f02b50b..12f326f 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -513,6 +513,7 @@ enum Lisp_Misc_Type
     Lisp_Misc_Overlay,
     Lisp_Misc_Save_Value,
     Lisp_Misc_Finalizer,
+    Lisp_Misc_Ptr,
 #ifdef HAVE_MODULES
     Lisp_Misc_User_Ptr,
 #endif
@@ -539,10 +540,11 @@ enum Lisp_Fwd_Type
 
    First, there are already a couple of Lisp types that can be used if
    your new type does not need to be exposed to Lisp programs nor
-   displayed to users.  These are Lisp_Save_Value, a Lisp_Misc
+   displayed to users.  These are Lisp_Misc_Ptr, a Lisp_Misc
    subtype; and PVEC_OTHER, a kind of vectorlike object.  The former
-   is suitable for temporarily stashing away pointers and integers in
-   a Lisp object.  The latter is useful for vector-like Lisp objects
+   is suitable for stashing a pointer in a Lisp object; the pointer
+   might be to some low-level C object that contains auxiliary
+   information.  The latter is useful for vector-like Lisp objects
    that need to be used as part of other objects, but which are never
    shown to users or Lisp code (search for PVEC_OTHER in xterm.c for
    an example).
@@ -2494,14 +2496,22 @@ XSAVE_FUNCPOINTER (Lisp_Object obj, int n)
   return XSAVE_VALUE (obj)->data[n].funcpointer;
 }
 
-extern Lisp_Object make_save_ptr (void *);
+struct Lisp_Misc_Ptr
+  {
+    ENUM_BF (Lisp_Misc_Type) type : 16;        /* = Lisp_Misc_Ptr */
+    bool_bf gcmarkbit : 1;
+    unsigned spacer : 15;
+    void *pointer;
+  };
+
+extern Lisp_Object make_misc_ptr (void *);
 
 /* A mint_ptr object OBJ represents a C-language pointer P efficiently.
    Preferably (and typically), OBJ is a Lisp integer I such that
    XINTPTR (I) == P, as this represents P within a single Lisp value
    without requiring any auxiliary memory.  However, if P would be
    damaged by being tagged as an integer and then untagged via
-   XINTPTR, then OBJ is a Lisp_Save_Value with pointer component P.
+   XINTPTR, then OBJ is a Lisp_Misc_Ptr with pointer component P.
 
    mint_ptr objects are efficiency hacks intended for C code.
    Although xmint_ptr can be given any mint_ptr generated by non-buggy
@@ -2515,14 +2525,13 @@ INLINE Lisp_Object
 make_mint_ptr (void *a)
 {
   Lisp_Object val = TAG_PTR (Lisp_Int0, a);
-  return INTEGERP (val) && XINTPTR (val) == a ? val : make_save_ptr (a);
+  return INTEGERP (val) && XINTPTR (val) == a ? val : make_misc_ptr (a);
 }
 
 INLINE bool
 mint_ptrp (Lisp_Object x)
 {
-  return (INTEGERP (x)
-         || (SAVE_VALUEP (x) && XSAVE_VALUE (x)->save_type == SAVE_POINTER));
+  return INTEGERP (x) || (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Ptr);
 }
 
 INLINE void *
@@ -2531,7 +2540,7 @@ xmint_pointer (Lisp_Object a)
   eassert (mint_ptrp (a));
   if (INTEGERP (a))
     return XINTPTR (a);
-  return XSAVE_POINTER (a, 0);
+  return XUNTAG (a, Lisp_Misc, struct Lisp_Misc_Ptr)->pointer;
 }
 
 /* Get and set the Nth saved integer.  */
@@ -2618,6 +2627,7 @@ union Lisp_Misc
     struct Lisp_Overlay u_overlay;
     struct Lisp_Save_Value u_save_value;
     struct Lisp_Finalizer u_finalizer;
+    struct Lisp_Misc_Ptr u_misc_ptr;
 #ifdef HAVE_MODULES
     struct Lisp_User_Ptr u_user_ptr;
 #endif
@@ -3855,6 +3865,7 @@ extern ptrdiff_t inhibit_garbage_collection (void);
 extern Lisp_Object make_save_int_int_int (ptrdiff_t, ptrdiff_t, ptrdiff_t);
 extern Lisp_Object make_save_obj_obj_obj_obj (Lisp_Object, Lisp_Object,
                                              Lisp_Object, Lisp_Object);
+extern Lisp_Object make_save_ptr (void *);
 extern Lisp_Object make_save_ptr_int (void *, ptrdiff_t);
 extern Lisp_Object make_save_ptr_ptr (void *, void *);
 extern Lisp_Object make_save_funcptr_ptr_obj (void (*) (void), void *,
diff --git a/src/print.c b/src/print.c
index 234f44a..741d1cc 100644
--- a/src/print.c
+++ b/src/print.c
@@ -2178,6 +2178,13 @@ print_object (Lisp_Object obj, Lisp_Object printcharfun, 
bool escapeflag)
          print_c_string ("#<misc free cell>", printcharfun);
          break;
 
+       case Lisp_Misc_Ptr:
+         {
+           int i = sprintf (buf, "#<ptr %p>", xmint_pointer (obj));
+           strout (buf, i, i, printcharfun);
+         }
+         break;
+
        case Lisp_Misc_Save_Value:
          {
            int i;
diff --git a/src/w32font.c b/src/w32font.c
index 9cbc3ee..65409b9 100644
--- a/src/w32font.c
+++ b/src/w32font.c
@@ -718,7 +718,7 @@ w32font_draw (struct glyph_string *s, int from, int to,
 }
 
 /* w32 implementation of free_entity for font backend.
-   Optional (if FONT_EXTRA_INDEX is not Lisp_Save_Value).
+   Optional.
    Free FONT_EXTRA_INDEX field of FONT_ENTITY.
 static void
 w32font_free_entity (Lisp_Object entity);