(mark_object): Declare ptr volatile, or don't use it

after a recursive call.  Delete the aborts if ptr is clobbered.

diff --git a/src/alloc.c b/src/alloc.c
index a411071067f2c14e13050a466fbf84916950c56d..c141f4a1e220f4b882188f098e3aff0b27811bdd 100644 (file)
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -1469,11 +1469,6 @@ mark_object (objptr)
 {
   register Lisp_Object obj;
 
-#ifdef DEBUG_MOLE
-  if (*(int *) ((char *)__builtin_frame_address (0) - 16) == 0)
-    abort ();
-#endif
-
   obj = *objptr;
   XUNMARK (obj);
 
@@ -1531,17 +1526,19 @@ mark_object (objptr)
       {
        register struct Lisp_Vector *ptr = XVECTOR (obj);
        register int size = ptr->size;
+       /* The reason we use ptr1 is to avoid an apparent hardware bug
+          that happens occasionally on the FSF's HP 300s.
+          The bug is that a2 gets clobbered by recursive calls to mark_object.
+          The clobberage seems to happen during function entry,
+          perhaps in the moveml instruction.
+          Yes, this is a crock, but we have to do it.  */
        struct Lisp_Vector *volatile ptr1 = ptr;
        register int i;
 
        if (size & ARRAY_MARK_FLAG) break;   /* Already marked */
        ptr->size |= ARRAY_MARK_FLAG; /* Else mark it */
        for (i = 0; i < size; i++)     /* and then mark its elements */
-         {
-           if (ptr != ptr1)
-             abort ();
-           mark_object (&ptr->contents[i]);
-         }
+         mark_object (&ptr1->contents[i]);
       }
       break;
 
@@ -1552,6 +1549,7 @@ mark_object (objptr)
       {
        register struct Lisp_Vector *ptr = XVECTOR (obj);
        register int size = ptr->size;
+       /* See comment above under Lisp_Vector.  */
        struct Lisp_Vector *volatile ptr1 = ptr;
        register int i;
 
@@ -1559,12 +1557,10 @@ mark_object (objptr)
        ptr->size |= ARRAY_MARK_FLAG; /* Else mark it */
        for (i = 0; i < size; i++)     /* and then mark its elements */
          {
-           if (ptr != ptr1)
-             abort ();
            if (i != COMPILED_CONSTANTS)
-             mark_object (&ptr->contents[i]);
+             mark_object (&ptr1->contents[i]);
          }
-       objptr = &ptr->contents[COMPILED_CONSTANTS];
+       objptr = &ptr1->contents[COMPILED_CONSTANTS];
        obj = *objptr;
        goto loop;
       }
@@ -1572,7 +1568,8 @@ mark_object (objptr)
 #ifdef MULTI_FRAME
     case Lisp_Frame:
       {
-       register struct frame *ptr = XFRAME (obj);
+       /* See comment above under Lisp_Vector for why this is volatile.  */
+       register struct frame *volatile ptr = XFRAME (obj);
        register int size = ptr->size;
 
        if (size & ARRAY_MARK_FLAG) break;   /* Already marked */
@@ -1595,24 +1592,17 @@ mark_object (objptr)
 
     case Lisp_Symbol:
       {
-       register struct Lisp_Symbol *ptr = XSYMBOL (obj);
+       /* See comment above under Lisp_Vector for why this is volatile.  */
+       register struct Lisp_Symbol *volatile ptr = XSYMBOL (obj);
        struct Lisp_Symbol *ptrx;
 
        if (XMARKBIT (ptr->plist)) break;
        XMARK (ptr->plist);
        mark_object ((Lisp_Object *) &ptr->value);
-       if ((unsigned int) ptr <= 4)
-         abort ();
        mark_object (&ptr->function);
-       if ((unsigned int) ptr <= 4)
-         abort ();
        mark_object (&ptr->plist);
-       if ((unsigned int) ptr <= 4)
-         abort ();
        XSETTYPE (*(Lisp_Object *) &ptr->name, Lisp_String);
        mark_object (&ptr->name);
-       if ((unsigned int) ptr <= 4)
-         abort ();
        ptr = ptr->next;
        if (ptr)
          {
@@ -1646,12 +1636,9 @@ mark_object (objptr)
            XUNMARK (obj);
            goto loop;
          }
-       if (ptr == 0)
-         abort ();
        mark_object (&ptr->car);
-       if (ptr == 0)
-         abort ();
-       objptr = &ptr->cdr;
+       /* See comment above under Lisp_Vector for why not use ptr here.  */
+       objptr = &XCONS (obj)->cdr;
        obj = ptr->cdr;
        goto loop;
       }