/*
* Copyright (c) 1999 by Silicon Graphics. 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.
*/
#ifdef NURSERY
??? This implementation is incomplete. If you are trying to
??? compile this you are doing something wrong.
#include "nursery.h"
#define SCAN_STATICS_FOR_NURSERY
/* If this is not defined, the collector will not see */
/* references from static data areas to the nursery. */
struct copy_obj {
ptr_t forward; /* Forwarding link for copied objects. */
GC_copy_descriptor descr; /* Object descriptor */
word data[1];
}
ptr_t GC_nursery_start; /* Start of nursery area. */
/* Must be NURSERY_BLOCK_SIZE */
/* aligned. */
ptr_t GC_nursery_end; /* End of nursery area. */
unsigned char * GC_nursery_map;
/* GC_nursery_map[i] != 0 if an object */
/* starts on the ith 64-bit "word" of */
/* nursery. This simple structure has */
/* the advantage that */
/* allocation is cheap. Lookup is */
/* cheap for pointers to the head of */
/* an object, which should be the */
/* usual case. */
# define NURSERY_MAP_NOT_START 0 /* Not start of object. */
# define NURSERY_MAP_START 1 /* Start of object. */
# define NURSERY_MAP_PINNED 2 /* Start of pinned obj. */
# ifdef ALIGN_DOUBLE
# define NURSERY_WORD_SIZE (2 * sizeof(word))
# else
# define NURSERY_WORD_SIZE sizeof(word)
# endif
# define NURSERY_BLOCK_SIZE (HBLKSIZE/2)
/* HBLKSIZE must be a multiple of NURSERY_BLOCK_SIZE */
# define NURSERY_SIZE (1024 * NURSERY_BLOCK_SIZE)
size_t GC_nursery_size = NURSERY_SIZE;
/* Must be multiple of NURSERY_BLOCK_SIZE */
size_t GC_nursery_blocks; /* Number of blocks in the nursery. */
unsigned GC_next_nursery_block; /* index of next block we will attempt */
/* allocate from during this cycle. */
/* If it is pinned, we won't actually */
/* use it. */
unsigned short *GC_pinned; /* Number of pinned objects in ith */
/* nursery block. */
/* GC_pinned[i] != 0 if the ith nursery */
/* block is pinned, and thus not used */
/* for allocation. */
GC_copy_alloc_state global_alloc_state = (ptr_t)(-1); /* will overflow. */
/* Array of known rescuing pointers from the heap to the nursery. */
ptr_t ** nursery_rescuers;
/* Pointer to one past the last slot in rescuer table */
ptr_t ** nursery_rescuers_end;
/* Maximum number of known rescuing pointers. */
# define MAX_NURSERY_RESCUERS 32*1024
/* Add a rescuer to the list */
# define ADD_NURSERY_RESCUER(p) \
if (nursery_rescuers_end >= nursery_rescuers + MAX_NURSERY_RESCUERS) { \
ABORT("Nursery recuers overflow"); /* Fix later !!! */ \
} else { \
*nursery_rescuers_end++ = p; \
}
/* Remove rescuer at the given position in the table */
# define REMOVE_RESCUER(p) \
*p = *--nursery_rescuers_end
/* Should be called with allocator lock held. */
GC_nursery_init() {
GC_nursery_start = GET_MEM(GC_nursery_size);
GC_nursery_end = GC_nursery_start + GC_nursery_size;
GC_next_nursery_block = 0;
if (GC_nursery_start < GC_least_plausible_heap_addr) {
GC_least_plausible_heap_addr = GC_nursery_start;
}
if (GC_nursery_end > GC_greatest_plausible_heap_addr) {
GC_greatest_plausible_heap_addr = GC_nursery_end;
}
if (GC_nursery_start & (NURSERY_BLOCK_SIZE-1)) {
GC_err_printf1("Nursery area is misaligned!!");
/* This should be impossible, since GET_MEM returns HBLKSIZE */
/* aligned chunks, and that should be a multiple of */
/* NURSERY_BLOCK_SIZE */
ABORT("misaligned nursery");
}
GC_nursery_map = GET_MEM(GC_nursery_size/NURSERY_WORD_SIZE);
/* Map is cleared a block at a time when we allocate from the block. */
/* BZERO(GC_nursery_map, GC_nursery_size/NURSERY_WORD_SIZE); */
GC_nursery_blocks = GC_nursery_size/NURSERY_BLOCK_SIZE;
GC_pinned = GC_scratch_alloc(GC_nursery_blocks * sizeof(unsigned short));
BZERO(GC_pinned, GC_nursery_blocks);
nursery_rescuers = GET_MEM(MAX_NURSERY_RESCUERS * sizeof(ptr_t *));
nursery_rescuers_end = nursery_rescuers;
if (0 == GC_nursery_start || 0 == GC_nursery_map || 0 == nursery_rescuers)
ABORT("Insufficient memory for nursery");
}
#define PIN_OBJ(p) \
if (p >= GC_nursery_start && p < GC_nursery_end) { GC_pin_obj_checked(p); }
/* Pin the object at p, if it's in the nursery. */
void GC_pin_obj(ptr_t p) {
PIN_OBJ(p);
}
void (*GC_push_proc)(ptr_t) = 0;
/* Pin the object at p, which is known to be in the nursery. */
void GC_pin_obj_checked(ptr_t p) {
unsigned offset = p - GC_nursery_start;
unsigned word_offset = BYTES_TO_WORDS(offset);
unsigned blockno = (current - GC_nursery_start)/NURSERY_BLOCK_SIZE;
while (GC_nursery_map[word_offset] == NURSERY_MAP_NOT_START) {
--word_offset;
}
if (GC_nursery_map[word_offset] != NURSERY_MAP_PINNED) {
GC_nursery_map[word_offset] = NURSERY_MAP_PINNED;
++GC_pinned[blockno];
??Push object at GC_nursery_start + WORDS_TO_BYTES(word_offset)
??onto mark stack.
}
}
void GC_scan_region_for_nursery(ptr_t low, ptr_t high) {
# if CPP_WORDSZ/8 != ALIGNMENT
--> fix this
# endif
word * l = (word *)((word)low + ALIGNMENT - 1 & ~(ALIGNMENT - 1));
word * h = (word *)((word)high & ~(ALIGNMENT - 1));
word * p;
for (p = l; p < h; ++p) {
PIN_OBJ(p);
}
}
/* Invoke GC_scan_region_for_nursery on ranges that are not excluded. */
void GC_scan_region_for_nursery_with_exclusions(ptr_t bottom, ptr_t top)
{
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_scan_region_for_nursery(bottom, top);
return;
}
if (excl_start > bottom)
GC_scan_region_for_nursery(bottom, excl_start);
bottom = next -> e_end;
}
}
void GC_scan_stacks_for_nursery(void) {
# ifdef THREADS
--> fix this
# endif
# ifdef STACK_GROWS_DOWN
ptr_t stack_low = GC_approx_sp();
ptr_t stack_high = GC_stackbottom;
# else
ptr_t stack_low = GC_stackbottom;
ptr_t stack_high = GC_approx_sp();
# endif
GC_scan_region_for_nursery(stack_low, stack_high);
# ifdef IA64
GC_scan_region_for_nursery(BACKING_STORE_BASE,
(ptr_t) GC_save_regs_ret_val);
# endif
}
void GC_scan_roots_for_nursery(void) {
/* Scan registers. */
/* Direct GC_push_one to call GC_pin_obj instead of marking */
/* and pushing objects. */
/* This is a bit ugly, but we don't have to touch the */
/* platform-dependent code. */
void (*old_push_proc)(ptr_t) = GC_push_proc;
GC_push_proc = GC_pin_obj;
GC_push_regs();
GC_push_proc = old_push_proc;
GC_scan_stacks_for_nursery();
# ifdef SCAN_STATICS_FOR_NURSERY
# 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_scan_region_for_nursery_with_exclusions (
GC_static_roots[i].r_start,
GC_static_roots[i].r_end);
}
# endif
}
/* Array of known rescuing pointers from the heap to the nursery. */
ptr_t ** nursery_rescuers;
/* Caller holds allocation lock. */
void GC_collect_nursery(void) {
int i;
ptr_t scan_ptr = 0;
STOP_WORLD;
for (i = 0; i < GC_nursery_blocks; ++i) GC_pinned[i] = 0;
GC_scan_roots_for_nursery();
/* All objects referenced by roots are now pinned. */
/* Their contents are described by */
/* mark stack entries. */
/* Pin blocks corresponding to valid allocation states. */
/* that probably happens automagically if the allocation */
/* states are kept where we can see them. */
/* It will take work if static roots are not scanned. */
/* We want to do this both for correctness and to avoid */
/* promoting very young objects. */
/* Somehow capture dirty bits. Update rescuers array to */
/* reflect newly valid and invalid references from dirty */
/* pages. Other references should remain valid, since the */
/* referents should have been pinned. */
/* Traverse the old object heap. Pin objects in the */
/* nursery that are ambiguously referenced, copy those */
/* that are unambiguously referenced. */
/* Traverse objects in mark stack. */
/* If referenced object is in pinned block, add contents */
/* to mark stack. If referenced object is forwarded, */
/* update pointer. Otherwise reallocate the object in the */
/* old heap, copy its contents, and then enqueue its */
/* contents in the mark stack. */
START_WORLD;
}
/* Initialize an allocation state so that it can be used for */
/* allocation. This implicitly reserves a small section of the */
/* nursery for use with this allocator. */
/* Also called to replenish an allocator that has been */
/* exhausted. */
void GC_init_copy_alloc_state(GC_copy_alloc_state *)
unsigned next_block;
ptr_t block_addr;
LOCK();
next_block = GC_next_nursery_block;
while(is_pinned[next_block] && next_block < GC_nursery_blocks) {
++next_block;
}
if (next_block < GC_nursery_blocks) {
block_addr = GC_nursery_start + NURSERY_BLOCK_SIZE * next_block;
GC_next_nursery_block = next_block + 1;
BZERO(GC_nursery_map + next_block *
(NURSERY_BLOCK_SIZE/NURSERY_WORD_SIZE),
NURSERY_BLOCK_SIZE/NURSERY_WORD_SIZE);
*GC_copy_alloc_state = block_addr;
UNLOCK();
} else {
GC_collect_nursery();
GC_next_nursery_block = 0;
UNLOCK();
get_new_block(s);
}
}
GC_PTR GC_copying_malloc2(GC_copy_descriptor *d, GC_copy_alloc_state *s) {
size_t sz = GC_SIZE_FROM_DESCRIPTOR(d);
ptrdiff_t offset;
ptr_t result = *s;
ptr_t new = result + sz;
if (new & COPY_BLOCK_MASK <= result & COPY_BLOCK_MASK> {
GC_init_copy_alloc_state(s);
result = *s;
new = result + sz;
GC_ASSERT(new & COPY_BLOCK_MASK > result & COPY_BLOCK_MASK>
}
(struct copy_obj *)result -> descr = d;
(struct copy_obj *)result -> forward = 0;
offset = (result - GC_nursery_start)/NURSERY_WORD_SIZE;
GC_nursery_map[offset] = NURSERY_MAP_NOT_START;
}
GC_PTR GC_copying_malloc(GC_copy_descriptor *d) {
}
#endif /* NURSERY */
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