[Emacs-diffs] Changes to emacs/gc/ptr_chck.c [Boehm-versions]

[Dave Love]

Index: emacs/gc/ptr_chck.c
diff -c /dev/null emacs/gc/ptr_chck.c:1.2.2.1.2.1
*** /dev/null   Mon Jun 16 11:20:05 2003
--- emacs/gc/ptr_chck.c Mon Jun 16 11:19:52 2003
***************
*** 0 ****
--- 1,328 ----
+ /* 
+  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
+  *
+  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
+  *
+  * Permission is hereby granted to use or copy this program
+  * for any purpose,  provided the above notices are retained on all copies.
+  * Permission to modify the code and to distribute modified code is granted,
+  * provided the above notices are retained, and a notice that the code was
+  * modified is included with the above copyright notice.
+  */
+ 
+ /*
+  * These are checking routines calls to which could be inserted by a
+  * preprocessor to validate C pointer arithmetic.
+  */
+ 
+ #include "private/gc_pmark.h"
+ 
+ #ifdef __STDC__
+ void GC_default_same_obj_print_proc(GC_PTR p, GC_PTR q)
+ #else
+ void GC_default_same_obj_print_proc (p, q)
+ GC_PTR p, q;
+ #endif
+ {
+     GC_err_printf2("0x%lx and 0x%lx are not in the same object\n",
+                  (unsigned long)p, (unsigned long)q);
+     ABORT("GC_same_obj test failed");
+ }
+ 
+ void (*GC_same_obj_print_proc) GC_PROTO((GC_PTR, GC_PTR))
+               = GC_default_same_obj_print_proc;
+ 
+ /* Check that p and q point to the same object.  Call         */
+ /* *GC_same_obj_print_proc if they don't.                     */
+ /* Returns the first argument.  (Return value may be hard     */
+ /* to use,due to typing issues.  But if we had a suitable     */
+ /* preprocessor ...)                                          */
+ /* Succeeds if neither p nor q points to the heap.            */
+ /* We assume this is performance critical.  (It shouldn't     */
+ /* be called by production code, but this can easily make     */
+ /* debugging intolerably slow.)                                       */
+ #ifdef __STDC__
+   GC_PTR GC_same_obj(register void *p, register void *q)
+ #else
+   GC_PTR GC_same_obj(p, q)
+   register char *p, *q;
+ #endif
+ {
+     register struct hblk *h;
+     register hdr *hhdr;
+     register ptr_t base, limit;
+     register word sz;
+     
+     if (!GC_is_initialized) GC_init();
+     hhdr = HDR((word)p);
+     if (hhdr == 0) {
+       if (divHBLKSZ((word)p) != divHBLKSZ((word)q)
+           && HDR((word)q) != 0) {
+           goto fail;
+       }
+       return(p);
+     }
+     /* If it's a pointer to the middle of a large object, move it     */
+     /* to the beginning.                                              */
+     if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
+       h = HBLKPTR(p) - (word)hhdr;
+       hhdr = HDR(h);
+       while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
+          h = FORWARDED_ADDR(h, hhdr);
+          hhdr = HDR(h);
+       }
+       limit = (ptr_t)((word *)h + hhdr -> hb_sz);
+       if ((ptr_t)p >= limit || (ptr_t)q >= limit || (ptr_t)q < (ptr_t)h ) {
+           goto fail;
+       }
+       return(p);
+     }
+     sz = WORDS_TO_BYTES(hhdr -> hb_sz);
+     if (sz > MAXOBJBYTES) {
+       base = (ptr_t)HBLKPTR(p);
+       limit = base + sz;
+       if ((ptr_t)p >= limit) {
+         goto fail;
+       }
+     } else {
+       register int map_entry;
+       register int pdispl = HBLKDISPL(p);
+       
+       map_entry = MAP_ENTRY((hhdr -> hb_map), pdispl);
+       if (map_entry > CPP_MAX_OFFSET) {
+          map_entry = BYTES_TO_WORDS(pdispl) % BYTES_TO_WORDS(sz);
+        if (HBLKPTR(p) != HBLKPTR(q)) goto fail;
+               /* W/o this check, we might miss an error if    */
+               /* q points to the first object on a page, and  */
+               /* points just before the page.                 */
+       }
+       base = (char *)((word)p & ~(WORDS_TO_BYTES(1) - 1));
+       base -= WORDS_TO_BYTES(map_entry);
+       limit = base + sz;
+     }
+     /* [base, limit) delimits the object containing p, if any.        */
+     /* If p is not inside a valid object, then either q is    */
+     /* also outside any valid object, or it is outside                */
+     /* [base, limit).                                         */
+     if ((ptr_t)q >= limit || (ptr_t)q < base) {
+       goto fail;
+     }
+     return(p);
+ fail:
+     (*GC_same_obj_print_proc)((ptr_t)p, (ptr_t)q);
+     return(p);
+ }
+ 
+ #ifdef __STDC__
+ void GC_default_is_valid_displacement_print_proc (GC_PTR p)
+ #else
+ void GC_default_is_valid_displacement_print_proc (p)
+ GC_PTR p;
+ #endif
+ {
+     GC_err_printf1("0x%lx does not point to valid object displacement\n",
+                  (unsigned long)p);
+     ABORT("GC_is_valid_displacement test failed");
+ }
+ 
+ void (*GC_is_valid_displacement_print_proc) GC_PROTO((GC_PTR)) = 
+       GC_default_is_valid_displacement_print_proc;
+ 
+ /* Check that if p is a pointer to a heap page, then it points to     */
+ /* a valid displacement within a heap object.                         */
+ /* Uninteresting with GC_all_interior_pointers.                               
*/
+ /* Always returns its argument.                                               
*/
+ /* Note that we don't lock, since nothing relevant about the header   */
+ /* should change while we have a valid object pointer to the block.   */
+ #ifdef __STDC__
+   void * GC_is_valid_displacement(void *p)
+ #else
+   char *GC_is_valid_displacement(p)
+   char *p;
+ #endif
+ {
+     register hdr *hhdr;
+     register word pdispl;
+     register struct hblk *h;
+     register map_entry_type map_entry;
+     register word sz;
+     
+     if (!GC_is_initialized) GC_init();
+     hhdr = HDR((word)p);
+     if (hhdr == 0) return(p);
+     h = HBLKPTR(p);
+     if (GC_all_interior_pointers) {
+       while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
+          h = FORWARDED_ADDR(h, hhdr);
+          hhdr = HDR(h);
+       }
+     }
+     if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
+       goto fail;
+     }
+     sz = WORDS_TO_BYTES(hhdr -> hb_sz);
+     pdispl = HBLKDISPL(p);
+     map_entry = MAP_ENTRY((hhdr -> hb_map), pdispl);
+     if (map_entry == OBJ_INVALID
+       || sz > MAXOBJBYTES && (ptr_t)p >= (ptr_t)h + sz) {
+       goto fail;
+     }
+     return(p);
+ fail:
+     (*GC_is_valid_displacement_print_proc)((ptr_t)p);
+     return(p);
+ }
+ 
+ #ifdef __STDC__
+ void GC_default_is_visible_print_proc(GC_PTR p)
+ #else
+ void GC_default_is_visible_print_proc(p)
+ GC_PTR p;
+ #endif
+ {
+     GC_err_printf1("0x%lx is not a GC visible pointer location\n",
+                  (unsigned long)p);
+     ABORT("GC_is_visible test failed");
+ }
+ 
+ void (*GC_is_visible_print_proc) GC_PROTO((GC_PTR p)) = 
+       GC_default_is_visible_print_proc;
+ 
+ /* Could p be a stack address? */
+ GC_bool GC_on_stack(p)
+ ptr_t p;
+ {
+ #   ifdef THREADS
+       return(TRUE);
+ #   else
+       int dummy;
+ #     ifdef STACK_GROWS_DOWN
+           if ((ptr_t)p >= (ptr_t)(&dummy) && (ptr_t)p < GC_stackbottom ) {
+               return(TRUE);
+           }
+ #     else
+           if ((ptr_t)p <= (ptr_t)(&dummy) && (ptr_t)p > GC_stackbottom ) {
+               return(TRUE);
+           }
+ #     endif
+       return(FALSE);
+ #   endif
+ }
+ 
+ /* Check that p is visible                                            */
+ /* to the collector as a possibly pointer containing location.                
*/
+ /* If it isn't invoke *GC_is_visible_print_proc.                      */
+ /* Returns the argument in all cases.  May erroneously succeed                
*/
+ /* in hard cases.  (This is intended for debugging use with           */
+ /* untyped allocations.  The idea is that it should be possible, though       
*/
+ /* slow, to add such a call to all indirect pointer stores.)          */
+ /* Currently useless for multithreaded worlds.                                
*/
+ #ifdef __STDC__
+   void * GC_is_visible(void *p)
+ #else
+   char *GC_is_visible(p)
+   char *p;
+ #endif
+ {
+     register hdr *hhdr;
+     
+     if ((word)p & (ALIGNMENT - 1)) goto fail;
+     if (!GC_is_initialized) GC_init();
+ #   ifdef THREADS
+       hhdr = HDR((word)p);
+         if (hhdr != 0 && GC_base(p) == 0) {
+             goto fail;
+         } else {
+             /* May be inside thread stack.  We can't do much. */
+             return(p);
+         }
+ #   else
+       /* Check stack first: */
+         if (GC_on_stack(p)) return(p);
+       hhdr = HDR((word)p);
+       if (hhdr == 0) {
+           GC_bool result;
+           
+           if (GC_is_static_root(p)) return(p);
+           /* Else do it again correctly:      */
+ #           if (defined(DYNAMIC_LOADING) || defined(MSWIN32) || \
+               defined(MSWINCE) || defined(PCR)) \
+                 && !defined(SRC_M3)
+               DISABLE_SIGNALS();
+               GC_register_dynamic_libraries();
+               result = GC_is_static_root(p);
+               ENABLE_SIGNALS();
+               if (result) return(p);
+ #         endif
+           goto fail;
+       } else {
+           /* p points to the heap. */
+           word descr;
+           ptr_t base = GC_base(p);    /* Should be manually inlined? */
+           
+           if (base == 0) goto fail;
+           if (HBLKPTR(base) != HBLKPTR(p)) hhdr = HDR((word)p);
+           descr = hhdr -> hb_descr;
+     retry:
+           switch(descr & GC_DS_TAGS) {
+               case GC_DS_LENGTH:
+                   if ((word)((ptr_t)p - (ptr_t)base) > (word)descr) goto fail;
+                   break;
+               case GC_DS_BITMAP:
+                   if ((ptr_t)p - (ptr_t)base
+                        >= WORDS_TO_BYTES(BITMAP_BITS)
+                        || ((word)p & (sizeof(word) - 1))) goto fail;
+                   if (!((1 << (WORDSZ - ((ptr_t)p - (ptr_t)base) - 1))
+                         & descr)) goto fail;
+                   break;
+               case GC_DS_PROC:
+                   /* We could try to decipher this partially.         */
+                   /* For now we just punt.                            */
+                   break;
+               case GC_DS_PER_OBJECT:
+                   if ((signed_word)descr >= 0) {
+                     descr = *(word *)((ptr_t)base + (descr & ~GC_DS_TAGS));
+                   } else {
+                     ptr_t type_descr = *(ptr_t *)base;
+                     descr = *(word *)(type_descr
+                             - (descr - (GC_DS_PER_OBJECT
+                                         - GC_INDIR_PER_OBJ_BIAS)));
+                   }
+                   goto retry;
+           }
+           return(p);
+       }
+ #   endif
+ fail:
+     (*GC_is_visible_print_proc)((ptr_t)p);
+     return(p);
+ }
+ 
+ 
+ GC_PTR GC_pre_incr (p, how_much)
+ GC_PTR *p;
+ size_t how_much;
+ {
+     GC_PTR initial = *p;
+     GC_PTR result = GC_same_obj((GC_PTR)((word)initial + how_much), initial);
+     
+     if (!GC_all_interior_pointers) {
+       (void) GC_is_valid_displacement(result);
+     }
+     return (*p = result);
+ }
+ 
+ GC_PTR GC_post_incr (p, how_much)
+ GC_PTR *p;
+ size_t how_much;
+ {
+     GC_PTR initial = *p;
+     GC_PTR result = GC_same_obj((GC_PTR)((word)initial + how_much), initial);
+  
+     if (!GC_all_interior_pointers) {
+       (void) GC_is_valid_displacement(result);
+     }
+     *p = result;
+     return(initial);
+ }