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gcc/boehm-gc/mark_rts.c

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/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* 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.
*/
# include <stdio.h>
# include "private/gc_priv.h"
/* Data structure for list of root sets. */
/* We keep a hash table, so that we can filter out duplicate additions. */
/* Under Win32, we need to do a better job of filtering overlaps, so */
/* we resort to sequential search, and pay the price. */
/* This is really declared in gc_priv.h:
struct roots {
ptr_t r_start;
ptr_t r_end;
# if !defined(MSWIN32) && !defined(MSWINCE)
struct roots * r_next;
# endif
GC_bool r_tmp;
-- Delete before registering new dynamic libraries
};
struct roots GC_static_roots[MAX_ROOT_SETS];
*/
int GC_no_dls = 0; /* Register dynamic library data segments. */
static int n_root_sets = 0;
/* GC_static_roots[0..n_root_sets) contains the valid root sets. */
# if !defined(NO_DEBUGGING)
/* For debugging: */
void GC_print_static_roots()
{
register int i;
size_t total = 0;
for (i = 0; i < n_root_sets; i++) {
GC_printf2("From 0x%lx to 0x%lx ",
(unsigned long) GC_static_roots[i].r_start,
(unsigned long) GC_static_roots[i].r_end);
if (GC_static_roots[i].r_tmp) {
GC_printf0(" (temporary)\n");
} else {
GC_printf0("\n");
}
total += GC_static_roots[i].r_end - GC_static_roots[i].r_start;
}
GC_printf1("Total size: %ld\n", (unsigned long) total);
if (GC_root_size != total) {
GC_printf1("GC_root_size incorrect: %ld!!\n",
(unsigned long) GC_root_size);
}
}
# endif /* NO_DEBUGGING */
/* Primarily for debugging support: */
/* Is the address p in one of the registered static */
/* root sections? */
GC_bool GC_is_static_root(p)
ptr_t p;
{
static int last_root_set = MAX_ROOT_SETS;
register int i;
if (last_root_set < n_root_sets
&& p >= GC_static_roots[last_root_set].r_start
&& p < GC_static_roots[last_root_set].r_end) return(TRUE);
for (i = 0; i < n_root_sets; i++) {
if (p >= GC_static_roots[i].r_start
&& p < GC_static_roots[i].r_end) {
last_root_set = i;
return(TRUE);
}
}
return(FALSE);
}
#if !defined(MSWIN32) && !defined(MSWINCE)
/*
# define LOG_RT_SIZE 6
# define RT_SIZE (1 << LOG_RT_SIZE) -- Power of 2, may be != MAX_ROOT_SETS
struct roots * GC_root_index[RT_SIZE];
-- Hash table header. Used only to check whether a range is
-- already present.
-- really defined in gc_priv.h
*/
static int rt_hash(addr)
char * addr;
{
word result = (word) addr;
# if CPP_WORDSZ > 8*LOG_RT_SIZE
result ^= result >> 8*LOG_RT_SIZE;
# endif
# if CPP_WORDSZ > 4*LOG_RT_SIZE
result ^= result >> 4*LOG_RT_SIZE;
# endif
result ^= result >> 2*LOG_RT_SIZE;
result ^= result >> LOG_RT_SIZE;
result &= (RT_SIZE-1);
return(result);
}
/* Is a range starting at b already in the table? If so return a */
/* pointer to it, else NIL. */
struct roots * GC_roots_present(b)
char *b;
{
register int h = rt_hash(b);
register struct roots *p = GC_root_index[h];
while (p != 0) {
if (p -> r_start == (ptr_t)b) return(p);
p = p -> r_next;
}
return(FALSE);
}
/* Add the given root structure to the index. */
static void add_roots_to_index(p)
struct roots *p;
{
register int h = rt_hash(p -> r_start);
p -> r_next = GC_root_index[h];
GC_root_index[h] = p;
}
# else /* MSWIN32 || MSWINCE */
# define add_roots_to_index(p)
# endif
word GC_root_size = 0;
void GC_add_roots(b, e)
char * b; char * e;
{
DCL_LOCK_STATE;
DISABLE_SIGNALS();
LOCK();
GC_add_roots_inner(b, e, FALSE);
UNLOCK();
ENABLE_SIGNALS();
}
/* Add [b,e) to the root set. Adding the same interval a second time */
/* is a moderately fast noop, and hence benign. We do not handle */
/* different but overlapping intervals efficiently. (We do handle */
/* them correctly.) */
/* Tmp specifies that the interval may be deleted before */
/* reregistering dynamic libraries. */
void GC_add_roots_inner(b, e, tmp)
char * b; char * e;
GC_bool tmp;
{
struct roots * old;
# if defined(MSWIN32) || defined(MSWINCE)
/* Spend the time to ensure that there are no overlapping */
/* or adjacent intervals. */
/* This could be done faster with e.g. a */
/* balanced tree. But the execution time here is */
/* virtually guaranteed to be dominated by the time it */
/* takes to scan the roots. */
{
register int i;
for (i = 0; i < n_root_sets; i++) {
old = GC_static_roots + i;
if ((ptr_t)b <= old -> r_end && (ptr_t)e >= old -> r_start) {
if ((ptr_t)b < old -> r_start) {
old -> r_start = (ptr_t)b;
GC_root_size += (old -> r_start - (ptr_t)b);
}
if ((ptr_t)e > old -> r_end) {
old -> r_end = (ptr_t)e;
GC_root_size += ((ptr_t)e - old -> r_end);
}
old -> r_tmp &= tmp;
break;
}
}
if (i < n_root_sets) {
/* merge other overlapping intervals */
struct roots *other;
for (i++; i < n_root_sets; i++) {
other = GC_static_roots + i;
b = (char *)(other -> r_start);
e = (char *)(other -> r_end);
if ((ptr_t)b <= old -> r_end && (ptr_t)e >= old -> r_start) {
if ((ptr_t)b < old -> r_start) {
old -> r_start = (ptr_t)b;
GC_root_size += (old -> r_start - (ptr_t)b);
}
if ((ptr_t)e > old -> r_end) {
old -> r_end = (ptr_t)e;
GC_root_size += ((ptr_t)e - old -> r_end);
}
old -> r_tmp &= other -> r_tmp;
/* Delete this entry. */
GC_root_size -= (other -> r_end - other -> r_start);
other -> r_start = GC_static_roots[n_root_sets-1].r_start;
other -> r_end = GC_static_roots[n_root_sets-1].r_end;
n_root_sets--;
}
}
return;
}
}
# else
old = GC_roots_present(b);
if (old != 0) {
if ((ptr_t)e <= old -> r_end) /* already there */ return;
/* else extend */
GC_root_size += (ptr_t)e - old -> r_end;
old -> r_end = (ptr_t)e;
return;
}
# endif
if (n_root_sets == MAX_ROOT_SETS) {
ABORT("Too many root sets\n");
}
GC_static_roots[n_root_sets].r_start = (ptr_t)b;
GC_static_roots[n_root_sets].r_end = (ptr_t)e;
GC_static_roots[n_root_sets].r_tmp = tmp;
# if !defined(MSWIN32) && !defined(MSWINCE)
GC_static_roots[n_root_sets].r_next = 0;
# endif
add_roots_to_index(GC_static_roots + n_root_sets);
GC_root_size += (ptr_t)e - (ptr_t)b;
n_root_sets++;
}
static GC_bool roots_were_cleared = FALSE;
void GC_clear_roots GC_PROTO((void))
{
DCL_LOCK_STATE;
DISABLE_SIGNALS();
LOCK();
roots_were_cleared = TRUE;
n_root_sets = 0;
GC_root_size = 0;
# if !defined(MSWIN32) && !defined(MSWINCE)
{
register int i;
for (i = 0; i < RT_SIZE; i++) GC_root_index[i] = 0;
}
# endif
UNLOCK();
ENABLE_SIGNALS();
}
/* Internal use only; lock held. */
static void GC_remove_root_at_pos(i)
int i;
{
GC_root_size -= (GC_static_roots[i].r_end - GC_static_roots[i].r_start);
GC_static_roots[i].r_start = GC_static_roots[n_root_sets-1].r_start;
GC_static_roots[i].r_end = GC_static_roots[n_root_sets-1].r_end;
GC_static_roots[i].r_tmp = GC_static_roots[n_root_sets-1].r_tmp;
n_root_sets--;
}
#if !defined(MSWIN32) && !defined(MSWINCE)
static void GC_rebuild_root_index()
{
register int i;
for (i = 0; i < RT_SIZE; i++) GC_root_index[i] = 0;
for (i = 0; i < n_root_sets; i++)
add_roots_to_index(GC_static_roots + i);
}
#endif
/* Internal use only; lock held. */
void GC_remove_tmp_roots()
{
register int i;
for (i = 0; i < n_root_sets; ) {
if (GC_static_roots[i].r_tmp) {
GC_remove_root_at_pos(i);
} else {
i++;
}
}
#if !defined(MSWIN32) && !defined(MSWINCE)
GC_rebuild_root_index();
#endif
}
#if !defined(MSWIN32) && !defined(MSWINCE)
void GC_remove_roots(b, e)
char * b; char * e;
{
DCL_LOCK_STATE;
DISABLE_SIGNALS();
LOCK();
GC_remove_roots_inner(b, e);
UNLOCK();
ENABLE_SIGNALS();
}
/* Should only be called when the lock is held */
void GC_remove_roots_inner(b,e)
char * b; char * e;
{
int i;
for (i = 0; i < n_root_sets; ) {
if (GC_static_roots[i].r_start >= (ptr_t)b && GC_static_roots[i].r_end <= (ptr_t)e) {
GC_remove_root_at_pos(i);
} else {
i++;
}
}
GC_rebuild_root_index();
}
#endif /* !defined(MSWIN32) && !defined(MSWINCE) */
#if defined(MSWIN32) || defined(_WIN32_WCE_EMULATION)
/* Workaround for the OS mapping and unmapping behind our back: */
/* Is the address p in one of the temporary static root sections? */
GC_bool GC_is_tmp_root(p)
ptr_t p;
{
static int last_root_set = MAX_ROOT_SETS;
register int i;
if (last_root_set < n_root_sets
&& p >= GC_static_roots[last_root_set].r_start
&& p < GC_static_roots[last_root_set].r_end)
return GC_static_roots[last_root_set].r_tmp;
for (i = 0; i < n_root_sets; i++) {
if (p >= GC_static_roots[i].r_start
&& p < GC_static_roots[i].r_end) {
last_root_set = i;
return GC_static_roots[i].r_tmp;
}
}
return(FALSE);
}
#endif /* MSWIN32 || _WIN32_WCE_EMULATION */
ptr_t GC_approx_sp()
{
VOLATILE word dummy;
dummy = 42; /* Force stack to grow if necessary. Otherwise the */
/* later accesses might cause the kernel to think we're */
/* doing something wrong. */
# ifdef _MSC_VER
# pragma warning(disable:4172)
# endif
return((ptr_t)(&dummy));
# ifdef _MSC_VER
# pragma warning(default:4172)
# endif
}
/*
* Data structure for excluded static roots.
* Real declaration is in gc_priv.h.
struct exclusion {
ptr_t e_start;
ptr_t e_end;
};
struct exclusion GC_excl_table[MAX_EXCLUSIONS];
-- Array of exclusions, ascending
-- address order.
*/
size_t GC_excl_table_entries = 0; /* Number of entries in use. */
/* Return the first exclusion range that includes an address >= start_addr */
/* Assumes the exclusion table contains at least one entry (namely the */
/* GC data structures). */
struct exclusion * GC_next_exclusion(start_addr)
ptr_t start_addr;
{
size_t low = 0;
size_t high = GC_excl_table_entries - 1;
size_t mid;
while (high > low) {
mid = (low + high) >> 1;
/* low <= mid < high */
if ((word) GC_excl_table[mid].e_end <= (word) start_addr) {
low = mid + 1;
} else {
high = mid;
}
}
if ((word) GC_excl_table[low].e_end <= (word) start_addr) return 0;
return GC_excl_table + low;
}
void GC_exclude_static_roots(start, finish)
GC_PTR start;
GC_PTR finish;
{
struct exclusion * next;
size_t next_index, i;
if (0 == GC_excl_table_entries) {
next = 0;
} else {
next = GC_next_exclusion(start);
}
if (0 != next) {
if ((word)(next -> e_start) < (word) finish) {
/* incomplete error check. */
ABORT("exclusion ranges overlap");
}
if ((word)(next -> e_start) == (word) finish) {
/* extend old range backwards */
next -> e_start = (ptr_t)start;
return;
}
next_index = next - GC_excl_table;
for (i = GC_excl_table_entries; i > next_index; --i) {
GC_excl_table[i] = GC_excl_table[i-1];
}
} else {
next_index = GC_excl_table_entries;
}
if (GC_excl_table_entries == MAX_EXCLUSIONS) ABORT("Too many exclusions");
GC_excl_table[next_index].e_start = (ptr_t)start;
GC_excl_table[next_index].e_end = (ptr_t)finish;
++GC_excl_table_entries;
}
/* Invoke push_conditional on ranges that are not excluded. */
void GC_push_conditional_with_exclusions(bottom, top, all)
ptr_t bottom;
ptr_t top;
int all;
{
struct exclusion * next;
ptr_t excl_start;
while (bottom < top) {
next = GC_next_exclusion(bottom);
if (0 == next || (excl_start = next -> e_start) >= top) {
GC_push_conditional(bottom, top, all);
return;
}
if (excl_start > bottom) GC_push_conditional(bottom, excl_start, all);
bottom = next -> e_end;
}
}
/*
* In the absence of threads, push the stack contents.
* In the presence of threads, push enough of the current stack
* to ensure that callee-save registers saved in collector frames have been
* seen.
*/
void GC_push_current_stack(cold_gc_frame)
ptr_t cold_gc_frame;
{
# if defined(THREADS)
if (0 == cold_gc_frame) return;
# ifdef STACK_GROWS_DOWN
GC_push_all_eager(GC_approx_sp(), cold_gc_frame);
/* For IA64, the register stack backing store is handled */
/* in the thread-specific code. */
# else
GC_push_all_eager( cold_gc_frame, GC_approx_sp() );
# endif
# else
# ifdef STACK_GROWS_DOWN
GC_push_all_stack_partially_eager( GC_approx_sp(), GC_stackbottom,
cold_gc_frame );
# ifdef IA64
/* We also need to push the register stack backing store. */
/* This should really be done in the same way as the */
/* regular stack. For now we fudge it a bit. */
/* Note that the backing store grows up, so we can't use */
/* GC_push_all_stack_partially_eager. */
{
extern word GC_save_regs_ret_val;
/* Previously set to backing store pointer. */
ptr_t bsp = (ptr_t) GC_save_regs_ret_val;
ptr_t cold_gc_bs_pointer;
if (GC_all_interior_pointers) {
cold_gc_bs_pointer = bsp - 2048;
if (cold_gc_bs_pointer < BACKING_STORE_BASE) {
cold_gc_bs_pointer = BACKING_STORE_BASE;
} else {
GC_push_all_stack(BACKING_STORE_BASE, cold_gc_bs_pointer);
}
} else {
cold_gc_bs_pointer = BACKING_STORE_BASE;
}
GC_push_all_eager(cold_gc_bs_pointer, bsp);
/* All values should be sufficiently aligned that we */
/* dont have to worry about the boundary. */
}
# endif
# else
GC_push_all_stack_partially_eager( GC_stackbottom, GC_approx_sp(),
cold_gc_frame );
# endif
# endif /* !THREADS */
}
/*
* Push GC internal roots. Only called if there is some reason to believe
* these would not otherwise get registered.
*/
void GC_push_gc_structures GC_PROTO((void))
{
GC_push_finalizer_structures();
GC_push_stubborn_structures();
# if defined(THREADS)
GC_push_thread_structures();
# endif
}
#ifdef THREAD_LOCAL_ALLOC
void GC_mark_thread_local_free_lists();
#endif
void GC_cond_register_dynamic_libraries()
{
# if (defined(DYNAMIC_LOADING) || defined(MSWIN32) || defined(MSWINCE) \
|| defined(PCR)) && !defined(SRC_M3)
GC_remove_tmp_roots();
if (!GC_no_dls) GC_register_dynamic_libraries();
# else
GC_no_dls = TRUE;
# endif
}
/*
* Call the mark routines (GC_tl_push for a single pointer, GC_push_conditional
* on groups of pointers) on every top level accessible pointer.
* If all is FALSE, arrange to push only possibly altered values.
* Cold_gc_frame is an address inside a GC frame that
* remains valid until all marking is complete.
* A zero value indicates that it's OK to miss some
* register values.
*/
void GC_push_roots(all, cold_gc_frame)
GC_bool all;
ptr_t cold_gc_frame;
{
int i;
int kind;
/*
* Next push static data. This must happen early on, since it's
* not robust against mark stack overflow.
*/
/* Reregister dynamic libraries, in case one got added. */
/* There is some argument for doing this as late as possible, */
/* especially on win32, where it can change asynchronously. */
/* In those cases, we do it here. But on other platforms, it's */
/* not safe with the world stopped, so we do it earlier. */
# if !defined(REGISTER_LIBRARIES_EARLY)
GC_cond_register_dynamic_libraries();
# endif
/* Mark everything in static data areas */
for (i = 0; i < n_root_sets; i++) {
GC_push_conditional_with_exclusions(
GC_static_roots[i].r_start,
GC_static_roots[i].r_end, all);
}
/* Mark all free list header blocks, if those were allocated from */
/* the garbage collected heap. This makes sure they don't */
/* disappear if we are not marking from static data. It also */
/* saves us the trouble of scanning them, and possibly that of */
/* marking the freelists. */
for (kind = 0; kind < GC_n_kinds; kind++) {
GC_PTR base = GC_base(GC_obj_kinds[kind].ok_freelist);
if (0 != base) {
GC_set_mark_bit(base);
}
}
/* Mark from GC internal roots if those might otherwise have */
/* been excluded. */
if (GC_no_dls || roots_were_cleared) {
GC_push_gc_structures();
}
/* Mark thread local free lists, even if their mark */
/* descriptor excludes the link field. */
/* If the world is not stopped, this is unsafe. It is */
/* also unnecessary, since we will do this again with the */
/* world stopped. */
# ifdef THREAD_LOCAL_ALLOC
if (GC_world_stopped) GC_mark_thread_local_free_lists();
# endif
/*
* Now traverse stacks, and mark from register contents.
* These must be done last, since they can legitimately overflow
* the mark stack.
*/
# ifdef USE_GENERIC_PUSH_REGS
GC_generic_push_regs(cold_gc_frame);
/* Also pushes stack, so that we catch callee-save registers */
/* saved inside the GC_push_regs frame. */
# else
/*
* push registers - i.e., call GC_push_one(r) for each
* register contents r.
*/
GC_push_regs(); /* usually defined in machine_dep.c */
GC_push_current_stack(cold_gc_frame);
/* In the threads case, this only pushes collector frames. */
/* In the case of linux threads on IA64, the hot section of */
/* the main stack is marked here, but the register stack */
/* backing store is handled in the threads-specific code. */
# endif
if (GC_push_other_roots != 0) (*GC_push_other_roots)();
/* In the threads case, this also pushes thread stacks. */
/* Note that without interior pointer recognition lots */
/* of stuff may have been pushed already, and this */
/* should be careful about mark stack overflows. */
}
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