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gcc/boehm-gc/mark_rts.c
Tom Tromey 73ffefd017 Initial revision 
From-SVN: r26246
1999-04-07 08:01:30 +00:00

462 lines
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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.
*/
/* Boehm, October 9, 1995 1:06 pm PDT */
# include <stdio.h>
# include "gc_priv.h"
/* MAX_ROOT_SETS is the maximum number of ranges that can be */
/* registered as static roots. */
# ifdef LARGE_CONFIG
# define MAX_ROOT_SETS 4096
# else
# ifdef PCR
# define MAX_ROOT_SETS 1024
# else
# ifdef MSWIN32
# define MAX_ROOT_SETS 512
/* Under NT, we add only written pages, which can result */
/* in many small root sets. */
# else
# define MAX_ROOT_SETS 64
# endif
# endif
# endif
# define MAX_EXCLUSIONS (MAX_ROOT_SETS/4)
/* Maximum number of segments that can be excluded from root sets. */
/* 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. */
struct roots {
ptr_t r_start;
ptr_t r_end;
# ifndef MSWIN32
struct roots * r_next;
# endif
GC_bool r_tmp;
/* Delete before registering new dynamic libraries */
};
static struct roots static_roots[MAX_ROOT_SETS];
static int n_root_sets = 0;
/* 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) static_roots[i].r_start,
(unsigned long) static_roots[i].r_end);
if (static_roots[i].r_tmp) {
GC_printf0(" (temporary)\n");
} else {
GC_printf0("\n");
}
total += static_roots[i].r_end - 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 = 0;
register int i;
if (p >= static_roots[last_root_set].r_start
&& p < static_roots[last_root_set].r_end) return(TRUE);
for (i = 0; i < n_root_sets; i++) {
if (p >= static_roots[i].r_start
&& p < static_roots[i].r_end) {
last_root_set = i;
return(TRUE);
}
}
return(FALSE);
}
#ifndef MSWIN32
# define LOG_RT_SIZE 6
# define RT_SIZE (1 << LOG_RT_SIZE) /* Power of 2, may be != MAX_ROOT_SETS */
static struct roots * root_index[RT_SIZE];
/* Hash table header. Used only to check whether a range is */
/* already present. */
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 = 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 = root_index[h];
root_index[h] = p;
}
# else /* MSWIN32 */
# 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;
# ifdef MSWIN32
/* 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 = 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 = 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 = static_roots[n_root_sets-1].r_start;
other -> r_end = 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");
}
static_roots[n_root_sets].r_start = (ptr_t)b;
static_roots[n_root_sets].r_end = (ptr_t)e;
static_roots[n_root_sets].r_tmp = tmp;
# ifndef MSWIN32
static_roots[n_root_sets].r_next = 0;
# endif
add_roots_to_index(static_roots + n_root_sets);
GC_root_size += (ptr_t)e - (ptr_t)b;
n_root_sets++;
}
void GC_clear_roots GC_PROTO((void))
{
DCL_LOCK_STATE;
DISABLE_SIGNALS();
LOCK();
n_root_sets = 0;
GC_root_size = 0;
# ifndef MSWIN32
{
register int i;
for (i = 0; i < RT_SIZE; i++) root_index[i] = 0;
}
# endif
UNLOCK();
ENABLE_SIGNALS();
}
/* Internal use only; lock held. */
void GC_remove_tmp_roots()
{
register int i;
for (i = 0; i < n_root_sets; ) {
if (static_roots[i].r_tmp) {
GC_root_size -= (static_roots[i].r_end - static_roots[i].r_start);
static_roots[i].r_start = static_roots[n_root_sets-1].r_start;
static_roots[i].r_end = static_roots[n_root_sets-1].r_end;
static_roots[i].r_tmp = static_roots[n_root_sets-1].r_tmp;
n_root_sets--;
} else {
i++;
}
}
# ifndef MSWIN32
{
register int i;
for (i = 0; i < RT_SIZE; i++) root_index[i] = 0;
for (i = 0; i < n_root_sets; i++) add_roots_to_index(static_roots + i);
}
# endif
}
ptr_t GC_approx_sp()
{
word dummy;
return((ptr_t)(&dummy));
}
/*
* Data structure for excluded static roots.
*/
struct exclusion {
ptr_t e_start;
ptr_t e_end;
};
struct exclusion excl_table[MAX_EXCLUSIONS];
/* Array of exclusions, ascending */
/* address order. */
size_t 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 = excl_table_entries - 1;
size_t mid;
while (high > low) {
mid = (low + high) >> 1;
/* low <= mid < high */
if ((word) excl_table[mid].e_end <= (word) start_addr) {
low = mid + 1;
} else {
high = mid;
}
}
if ((word) excl_table[low].e_end <= (word) start_addr) return 0;
return 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 == 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 - excl_table;
for (i = excl_table_entries; i > next_index; --i) {
excl_table[i] = excl_table[i-1];
}
} else {
next_index = excl_table_entries;
}
if (excl_table_entries == MAX_EXCLUSIONS) ABORT("Too many exclusions");
excl_table[next_index].e_start = (ptr_t)start;
excl_table[next_index].e_end = (ptr_t)finish;
++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;
}
}
/*
* 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.
*/
void GC_push_roots(all)
GC_bool all;
{
register int i;
/*
* push registers - i.e., call GC_push_one(r) for each
* register contents r.
*/
GC_push_regs(); /* usually defined in machine_dep.c */
/*
* 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. */
# if (defined(DYNAMIC_LOADING) || defined(MSWIN32) || defined(PCR)) \
&& !defined(SRC_M3)
GC_remove_tmp_roots();
GC_register_dynamic_libraries();
# endif
/* Mark everything in static data areas */
for (i = 0; i < n_root_sets; i++) {
GC_push_conditional_with_exclusions(
static_roots[i].r_start,
static_roots[i].r_end, all);
}
/*
* Now traverse stacks.
*/
# ifndef THREADS
/* Mark everything on the stack. */
# ifdef STACK_GROWS_DOWN
GC_push_all_stack( GC_approx_sp(), GC_stackbottom );
# else
GC_push_all_stack( GC_stackbottom, GC_approx_sp() );
# endif
# endif
if (GC_push_other_roots != 0) (*GC_push_other_roots)();
/* In the threads case, this also pushes thread stacks. */
}
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