/*

* 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.

*/

/* Boehm, September 19, 1995 1:26 pm PDT */

#include "gc_priv.h"

#include "gc_mark.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 + HDR_WORDS + 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 > WORDS_TO_BYTES(MAXOBJSZ)) {

base = (ptr_t)HBLKPTR(p);

limit = base + sz;

if ((ptr_t)p >= limit) {

goto fail;

}

} else {

# ifdef ALL_INTERIOR_POINTERS

register map_entry_type map_entry;

register int pdispl;

pdispl = HBLKDISPL(p);

map_entry = MAP_ENTRY((hhdr -> hb_map), pdispl);

if (map_entry == OBJ_INVALID) {

goto fail;

} else {

base = (char *)((word)p & ~(WORDS_TO_BYTES(1) - 1));

base -= WORDS_TO_BYTES(map_entry);

}

# else

register int offset = HBLKDISPL(p) - HDR_BYTES;

register word correction = offset % sz;

if (HBLKPTR(p) != HBLKPTR(q)) {

/* The following computation otherwise fails in this case */

goto fail;

}

base = (ptr_t)p - correction;

# endif

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 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);

# ifdef ALL_INTERIOR_POINTERS

while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {

h = FORWARDED_ADDR(h, hhdr);

hhdr = HDR(h);

}

# endif

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 > MAXOBJSZ && (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(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 & DS_TAGS) {

case DS_LENGTH:

if ((word)((ptr_t)p - (ptr_t)base) > (word)descr) goto fail;

break;

case 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 DS_PROC:

/* We could try to decipher this partially. */

/* For now we just punt. */

break;

case DS_PER_OBJECT:

descr = *(word *)((ptr_t)base + (descr & ~DS_TAGS));

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);

# ifndef ALL_INTERIOR_POINTERS

(void) GC_is_valid_displacement(result);

# endif

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);

# ifndef ALL_INTERIOR_POINTERS

(void) GC_is_valid_displacement(result);

# endif

*p = result;

return(initial);

}