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Added tests + fixed bunch of bugs in GC implementation

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This commit is contained in:
Egor Sheremetov 2023-04-26 14:22:14 +02:00
parent 3826c8dd32
commit 313997496d
9 changed files with 1577 additions and 1534 deletions
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15
runtime/Makefile
View file

@ -1,15 +1,22 @@
CC=gcc
all: gc_runtime.o gc.o runtime.o all: gc_runtime.o gc.o runtime.o test.o
ar rc runtime.a gc_runtime.o runtime.o gc.o ar rc runtime.a gc_runtime.o runtime.o gc.o
test.o: gc.o gc_runtime.o runtime.o virt_stack.o test_main.c test_util.s
$(CC) -o test.o -g2 -fstack-protector-all -m32 gc.o gc_runtime.o virt_stack.o runtime.o test_main.c test_util.s
virt_stack.o: virt_stack.h virt_stack.c
$(CC) -g2 -fstack-protector-all -m32 -c virt_stack.c
gc.o: gc.c gc.h gc.o: gc.c gc.h
$(CC) -g -fstack-protector-all -m32 -c gc.c $(CC) -g2 -fstack-protector-all -m32 -c gc.c
gc_runtime.o: gc_runtime.s gc_runtime.o: gc_runtime.s
$(CC) -g -fstack-protector-all -m32 -c gc_runtime.s $(CC) -g2 -fstack-protector-all -m32 -c gc_runtime.s
runtime.o: runtime.c runtime.h runtime.o: runtime.c runtime.h
$(CC) -g -fstack-protector-all -m32 -c runtime.c $(CC) -g2 -fstack-protector-all -m32 -c runtime.c
clean: clean:
$(RM) *.a *.o *~ $(RM) *.a *.o *~

251
runtime/gc.c
View file

@ -1,30 +1,46 @@
# define _GNU_SOURCE 1 # define _GNU_SOURCE 1
#include "gc.h"
#include "runtime_common.h"
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
#include <time.h> #include <time.h>
#include <sys/mman.h> #include <sys/mman.h>
#include <string.h> #include <string.h>
#include "gc.h" #include <assert.h>
#include "runtime_common.h"
#ifdef DEBUG_VERSION
#include <signal.h>
#endif
#ifndef DEBUG_VERSION #ifndef DEBUG_VERSION
static const size_t INIT_HEAP_SIZE = 1 << 18; static const size_t INIT_HEAP_SIZE = 1 << 18;
#else #else
static const size_t INIT_HEAP_SIZE = 8; static const size_t INIT_HEAP_SIZE = 8;
#endif #endif
static const size_t SIZE_T_CHARS = sizeof(size_t)/sizeof(char);
#ifdef DEBUG_VERSION #ifdef DEBUG_VERSION
static const size_t cur_id = 1; size_t cur_id = 0;
#endif #endif
static extra_roots_pool extra_roots; static extra_roots_pool extra_roots;
extern size_t __gc_stack_top, __gc_stack_bottom; extern size_t __gc_stack_top, __gc_stack_bottom;
#ifndef DEBUG_VERSION
extern const size_t __start_custom_data, __stop_custom_data;
#endif
#ifdef DEBUG_VERSION
memory_chunk heap;
#else
static memory_chunk heap; static memory_chunk heap;
#endif
void *alloc(size_t size) { void *alloc(size_t size) {
#ifdef DEBUG_VERSION
++cur_id;
#endif
size = BYTES_TO_WORDS(size); size = BYTES_TO_WORDS(size);
void *p = gc_alloc_on_existing_heap(size); void *p = gc_alloc_on_existing_heap(size);
if (!p) { if (!p) {
@ -35,54 +51,78 @@ void* alloc(size_t size) {
} }
void *gc_alloc_on_existing_heap(size_t size) { void *gc_alloc_on_existing_heap(size_t size) {
if (heap.current + size < heap.end) { if (heap.current + size <= heap.end) {
void *p = (void *) heap.current; void *p = (void *) heap.current;
heap.current += size; heap.current += size;
memset(p, 0, size * sizeof(size_t));
return p; return p;
} }
return NULL; return NULL;
} }
void *gc_alloc(size_t size) { void *gc_alloc(size_t size) {
// mark phase mark_phase();
// TODO: add extra roots and static area scan
__gc_root_scan_stack();
// compact phase compact_phase(size);
compact(size);
return gc_alloc_on_existing_heap(size); return gc_alloc_on_existing_heap(size);
} }
void compact(size_t additional_size) { void mark_phase(void) {
__gc_root_scan_stack();
scan_extra_roots();
#ifndef DEBUG_VERSION
scan_global_area();
#endif
}
void compact_phase(size_t additional_size) {
size_t live_size = compute_locations(); size_t live_size = compute_locations();
size_t next_heap_size = MAX(live_size * EXTRA_ROOM_HEAP_COEFFICIENT + additional_size, MINIMUM_HEAP_CAPACITY); size_t next_heap_size = MAX(live_size * EXTRA_ROOM_HEAP_COEFFICIENT + additional_size, MINIMUM_HEAP_CAPACITY);
size_t next_heap_pseudo_size = MAX(next_heap_size, heap.size); // this is weird but here is why it happens:
// if we allocate too little heap right now, we may loose access to some alive objects
// however, after we physically relocate all of our objects we will shrink allocated memory if it is possible
memory_chunk new_memory; memory_chunk old_heap = heap;
new_memory.begin = mremap( heap.begin = mremap(
heap.begin,
WORDS_TO_BYTES(heap.size),
WORDS_TO_BYTES(next_heap_pseudo_size),
MREMAP_MAYMOVE
);
if (heap.begin == MAP_FAILED) {
perror("ERROR: compact_phase: mremap failed\n");
exit(1);
}
heap.end = heap.begin + next_heap_pseudo_size;
heap.size = next_heap_pseudo_size;
heap.current = heap.begin + (old_heap.current - old_heap.begin);
update_references(&old_heap);
physically_relocate(&old_heap);
// shrink it if possible, otherwise this code won'test_small_tree_compaction do anything, in both cases references will remain valid
heap.begin = mremap(
heap.begin, heap.begin,
WORDS_TO_BYTES(heap.size), WORDS_TO_BYTES(heap.size),
WORDS_TO_BYTES(next_heap_size), WORDS_TO_BYTES(next_heap_size),
MREMAP_MAYMOVE 0 // in this case we don't set MREMAP_MAYMOVE because it shouldn'test_small_tree_compaction move :)
); );
if (new_memory.begin == MAP_FAILED) { if (heap.begin == MAP_FAILED) {
perror ("ERROR: compact: mremap failed\n"); perror("ERROR: compact_phase: mremap failed\n");
exit(1); exit(1);
} }
new_memory.end = new_memory.begin + next_heap_size; heap.end = heap.begin + next_heap_size;
new_memory.size = next_heap_size; heap.size = next_heap_size;
new_memory.current = new_memory.begin + live_size; heap.current = heap.begin + live_size;
update_references(&new_memory);
physically_relocate(&new_memory);
} }
size_t compute_locations() { size_t compute_locations() {
size_t *free_ptr = heap.begin; size_t *free_ptr = heap.begin;
heap_iterator scan_iter = heap_begin_iterator(); heap_iterator scan_iter = heap_begin_iterator();
for (; heap_is_done_iterator(&scan_iter); heap_next_obj_iterator(&scan_iter)) { for (; !heap_is_done_iterator(&scan_iter); heap_next_obj_iterator(&scan_iter)) {
void *header_ptr = scan_iter.current; void *header_ptr = scan_iter.current;
void *obj_content = get_object_content_ptr(header_ptr); void *obj_content = get_object_content_ptr(header_ptr);
size_t sz = BYTES_TO_WORDS(obj_size_header_ptr(header_ptr)); size_t sz = BYTES_TO_WORDS(obj_size_header_ptr(header_ptr));
@ -94,32 +134,66 @@ size_t compute_locations() {
} }
// it will return number of words // it will return number of words
return scan_iter.current - heap.begin; return free_ptr - heap.begin;
} }
// TODO: fix pointers on stack and in static area void scan_and_fix_region(memory_chunk *old_heap, void *start, void *end) {
void update_references(memory_chunk *next_memory) { for (size_t *ptr = (size_t *) start; ptr < (size_t *) end; ++ptr) {
size_t ptr_value = *ptr;
// this can't be expressed via is_valid_heap_pointer, because this pointer may point area corresponding to the old heap
if (is_valid_pointer((size_t *) ptr_value)
&& (size_t) old_heap->begin <= ptr_value
&& ptr_value < (size_t) old_heap->current
) {
void *obj_ptr = (void*) heap.begin + ((void *) ptr_value - (void *) old_heap->begin);
void *new_addr = (void*) heap.begin + ((void *) get_forward_address(obj_ptr) - (void *) old_heap->begin);
size_t content_offset = get_header_size(get_type_row_ptr(obj_ptr));
*(void **) ptr = new_addr + content_offset;
}
}
}
void update_references(memory_chunk *old_heap) {
heap_iterator it = heap_begin_iterator(); heap_iterator it = heap_begin_iterator();
while (!heap_is_done_iterator(&it)) { while (!heap_is_done_iterator(&it)) {
if (is_marked(get_object_content_ptr(it.current))) {
for ( for (
obj_field_iterator field_iter = ptr_field_begin_iterator(it.current); obj_field_iterator field_iter = ptr_field_begin_iterator(it.current);
!field_is_done_iterator(&field_iter); !field_is_done_iterator(&field_iter);
obj_next_ptr_field_iterator(&field_iter) obj_next_ptr_field_iterator(&field_iter)
) { ) {
void *field_obj_content = *(void **) field_iter.cur_field; // TODO: create iterator method 'dereference', so that code would be a bit more readable
// this pointer should also be modified according to old_heap->begin
void *field_obj_content_addr = (void *) heap.begin + (*(void **) field_iter.cur_field - (void *) old_heap->begin); // TODO: vstack_create iterator method 'dereference', so that code would be a bit more readable
// important, we calculate new_addr very carefully here, because objects may relocate to another memory chunk // important, we calculate new_addr very carefully here, because objects may relocate to another memory chunk
size_t *new_addr = next_memory->begin + ((size_t *) get_forward_address(field_obj_content) - heap.begin); void *new_addr =
heap.begin + ((size_t *) get_forward_address(field_obj_content_addr) - (size_t *) old_heap->begin);
// update field reference to point to new_addr // update field reference to point to new_addr
// since, we want fields to point to actual content, we need to add this extra content_offset // since, we want fields to point to an actual content, we need to add this extra content_offset
// because forward_address itself is pointer to object header // because forward_address itself is a pointer to the object's header
size_t content_offset = get_header_size(get_type_row_ptr(field_obj_content)); size_t content_offset = get_header_size(get_type_row_ptr(field_obj_content_addr));
if (!is_valid_heap_pointer((void *) (new_addr + content_offset))) {
fprintf(stderr, "ur: incorrect pointer assignment: on object with id %d", TO_DATA(get_object_content_ptr(it.current))->id);
exit(1);
}
*(void **) field_iter.cur_field = new_addr + content_offset; *(void **) field_iter.cur_field = new_addr + content_offset;
} }
}
heap_next_obj_iterator(&it); heap_next_obj_iterator(&it);
} }
// fix pointers from stack
scan_and_fix_region(old_heap, (void*) __gc_stack_top, (void*) __gc_stack_bottom);
// fix pointers from extra_roots
scan_and_fix_region(old_heap, (void*) extra_roots.roots, (size_t*) extra_roots.roots + extra_roots.current_free);
#ifndef DEBUG_VERSION
// fix pointers from static area
scan_and_fix_region(old_heap, (void*) &__start_custom_data, (void*) &__stop_custom_data);
#endif
} }
void physically_relocate(memory_chunk *next_memory) { void physically_relocate(memory_chunk *old_heap) {
heap_iterator from_iter = heap_begin_iterator(); heap_iterator from_iter = heap_begin_iterator();
while (!heap_is_done_iterator(&from_iter)) { while (!heap_is_done_iterator(&from_iter)) {
@ -127,16 +201,20 @@ void physically_relocate(memory_chunk *next_memory) {
if (is_marked(obj)) { if (is_marked(obj)) {
// Move the object from its old location to its new location relative to // Move the object from its old location to its new location relative to
// the heap's (possibly new) location, 'to' points to future object header // the heap's (possibly new) location, 'to' points to future object header
void* to = next_memory->begin + ((size_t *) get_forward_address(obj) - heap.begin); size_t *to = heap.begin + ((size_t *) get_forward_address(obj) - (size_t *) old_heap->begin);
memmove(to, from_iter.current, BYTES_TO_WORDS(obj_size_header_ptr(obj))); memmove(to, from_iter.current, obj_size_header_ptr(from_iter.current));
unmark_object(to + ((size_t *) obj - from_iter.current)); unmark_object(get_object_content_ptr(to));
} }
heap_next_obj_iterator(&from_iter); heap_next_obj_iterator(&from_iter);
} }
} }
bool is_valid_heap_pointer(const size_t *p) { bool is_valid_heap_pointer(const size_t *p) {
return !UNBOXED(p) && (size_t) heap.begin <= (size_t) p && (size_t) p < (size_t) heap.end; return !UNBOXED(p) && (size_t) heap.begin <= (size_t) p && (size_t) p < (size_t) heap.current;
}
bool is_valid_pointer(const size_t *p) {
return !UNBOXED(p);
} }
void mark(void *obj) { void mark(void *obj) {
@ -153,10 +231,26 @@ void mark(void *obj) {
!field_is_done_iterator(&ptr_field_it); !field_is_done_iterator(&ptr_field_it);
obj_next_ptr_field_iterator(&ptr_field_it) obj_next_ptr_field_iterator(&ptr_field_it)
) { ) {
mark(ptr_field_it.cur_field); mark(* (void **) ptr_field_it.cur_field);
} }
} }
void scan_extra_roots(void) {
for (int i = 0; i < extra_roots.current_free; ++i) {
// this dereferencing is safe since runtime is pushing correct pointers into extra_roots
mark(*extra_roots.roots[i]);
}
}
#ifndef DEBUG_VERSION
void scan_global_area(void) {
// __start_custom_data is pointing to beginning of global area, thus all dereferencings are safe
for (const size_t *ptr = &__start_custom_data; ptr < &__stop_custom_data; ++ptr) {
mark(*(void **)ptr);
}
}
#endif
extern void gc_test_and_mark_root(size_t **root) { extern void gc_test_and_mark_root(size_t **root) {
mark((void *) *root); mark((void *) *root);
} }
@ -178,6 +272,19 @@ extern void __init (void) {
clear_extra_roots(); clear_extra_roots();
} }
extern void __shutdown(void) {
munmap(heap.begin, heap.size);
#ifdef DEBUG_VERSION
cur_id = 0;
#endif
heap.begin = NULL;
heap.end = NULL;
heap.size = 0;
heap.current = NULL;
__gc_stack_top = 0;
__gc_stack_bottom = 0;
}
void clear_extra_roots(void) { void clear_extra_roots(void) {
extra_roots.current_free = 0; extra_roots.current_free = 0;
} }
@ -207,18 +314,19 @@ void pop_extra_root (void ** p) {
#ifdef DEBUG_VERSION #ifdef DEBUG_VERSION
void objects_snapshot(void *objects_ptr, size_t objects_cnt) { size_t objects_snapshot(int *object_ids_buf, size_t object_ids_buf_size) {
size_t *ids_ptr = (size_t *) objects_ptr; size_t *ids_ptr = (size_t *) object_ids_buf;
size_t i = 0; size_t i = 0;
for ( for (
heap_iterator it = heap_begin_iterator(); heap_iterator it = heap_begin_iterator();
!heap_is_done_iterator(&it) && i < objects_cnt; !heap_is_done_iterator(&it) && i < object_ids_buf_size;
heap_next_obj_iterator(&it) heap_next_obj_iterator(&it), ++i
) { ) {
void *header_ptr = it.current; void *header_ptr = it.current;
data *d = TO_DATA(get_object_content_ptr(header_ptr)); data *d = TO_DATA(get_object_content_ptr(header_ptr));
ids_ptr[i] = d->id; ids_ptr[i] = d->id;
} }
return i;
} }
void set_stack(size_t stack_top, size_t stack_bottom) { void set_stack(size_t stack_top, size_t stack_bottom) {
@ -241,7 +349,7 @@ size_t get_forward_address(void *obj) {
return GET_FORWARD_ADDRESS(d->forward_address); return GET_FORWARD_ADDRESS(d->forward_address);
} }
size_t set_forward_address(void *obj, size_t addr) { void set_forward_address(void *obj, size_t addr) {
data *d = TO_DATA(obj); data *d = TO_DATA(obj);
SET_FORWARD_ADDRESS(d->forward_address, addr); SET_FORWARD_ADDRESS(d->forward_address, addr);
} }
@ -296,7 +404,12 @@ lama_type get_type_header_ptr(void *ptr) {
case SEXP_TAG: case SEXP_TAG:
return SEXP; return SEXP;
default: default:
#ifdef DEBUG_VERSION
fprintf(stderr, "ERROR: get_type_header_ptr: unknown object header, cur_id=%d", cur_id);
raise(SIGINT); // only for debug purposes
#else
perror("ERROR: get_type_header_ptr: unknown object header"); perror("ERROR: get_type_header_ptr: unknown object header");
#endif
exit(1); exit(1);
} }
} }
@ -319,6 +432,9 @@ size_t obj_size_header_ptr(void *ptr) {
return sexp_size(len); return sexp_size(len);
default: default:
perror("ERROR: obj_size_header_ptr: unknown object header"); perror("ERROR: obj_size_header_ptr: unknown object header");
#ifdef DEBUG_VERSION
raise(SIGINT); // only for debug purposes
#endif
exit(1); exit(1);
} }
} }
@ -336,18 +452,22 @@ size_t closure_size(size_t sz) {
return get_header_size(CLOSURE) + MEMBER_SIZE * sz; return get_header_size(CLOSURE) + MEMBER_SIZE * sz;
} }
size_t sexp_size(size_t sz) { size_t sexp_size(size_t members) {
return get_header_size(SEXP) + MEMBER_SIZE * sz; return get_header_size(SEXP) + MEMBER_SIZE * members;
} }
obj_field_iterator field_begin_iterator(void *obj) { obj_field_iterator field_begin_iterator(void *obj) {
lama_type type = get_type_row_ptr(obj); lama_type type = get_type_header_ptr(obj);
obj_field_iterator it = { .type=type, .obj_ptr=get_obj_header_ptr(obj, type), .cur_field=obj }; obj_field_iterator it = {.type=type, .obj_ptr=obj, .cur_field=get_object_content_ptr(obj)};
// since string doesn't have any actual fields we set cur_field to the end of object // since string doesn't have any actual fields we set cur_field to the end of object
if (type == STRING) { if (type == STRING) {
it.cur_field = get_end_of_obj(it.obj_ptr); it.cur_field = get_end_of_obj(it.obj_ptr);
} }
// skip first member which is basically pointer to the code
if (type == CLOSURE) {
it.cur_field += MEMBER_SIZE;
}
return it; return it;
} }
@ -357,7 +477,7 @@ obj_field_iterator ptr_field_begin_iterator(void *obj) {
if (field_is_done_iterator(&it)) { if (field_is_done_iterator(&it)) {
return it; return it;
} }
if (is_valid_heap_pointer(it.cur_field)) { if (is_valid_pointer(*(size_t **) it.cur_field)) {
return it; return it;
} }
obj_next_ptr_field_iterator(&it); obj_next_ptr_field_iterator(&it);
@ -371,7 +491,7 @@ void obj_next_field_iterator(obj_field_iterator *it) {
void obj_next_ptr_field_iterator(obj_field_iterator *it) { void obj_next_ptr_field_iterator(obj_field_iterator *it) {
do { do {
obj_next_field_iterator(it); obj_next_field_iterator(it);
} while (!field_is_done_iterator(it) && !is_valid_heap_pointer(it->cur_field)); } while (!field_is_done_iterator(it) && !is_valid_pointer(*(size_t **) it->cur_field));
} }
bool field_is_done_iterator(obj_field_iterator *it) { bool field_is_done_iterator(obj_field_iterator *it) {
@ -401,7 +521,42 @@ size_t get_header_size(lama_type type) {
return SEXP_ONLY_HEADER_SZ + DATA_HEADER_SZ; return SEXP_ONLY_HEADER_SZ + DATA_HEADER_SZ;
default: default:
perror("ERROR: get_header_size: unknown object type"); perror("ERROR: get_header_size: unknown object type");
#ifdef DEBUG_VERSION
raise(SIGINT); // only for debug purposes
#endif
exit(1); exit(1);
} }
} }
void *alloc_string(int len) {
data *obj = alloc(string_size(len));
obj->data_header = STRING_TAG | (len << 3);
obj->id = cur_id;
obj->forward_address = 0;
return obj;
}
void *alloc_array(int len) {
data *obj = alloc(array_size(len));
obj->data_header = ARRAY_TAG | (len << 3);
obj->id = cur_id;
obj->forward_address = 0;
return obj;
}
void *alloc_sexp(int members) {
sexp *obj = alloc(sexp_size(members));
obj->sexp_header = obj->contents.data_header = SEXP_TAG | (members << 3);
obj->contents.id = cur_id;
obj->contents.forward_address = 0;
obj->tag = 0;
return obj;
}
void *alloc_closure(int captured) {
data *obj = alloc(closure_size(captured));
obj->data_header = CLOSURE_TAG | (captured << 3);
obj->id = cur_id;
obj->forward_address = 0;
return obj;
}

58
runtime/gc.h
View file

@ -1,22 +1,26 @@
#ifndef __LAMA_GC__ #ifndef __LAMA_GC__
#define __LAMA_GC__ #define __LAMA_GC__
// this flag makes GC behavior a bit different for testing purposes.
#define DEBUG_VERSION
# define GET_MARK_BIT(x) (((int) (x)) & 1) # define GET_MARK_BIT(x) (((int) (x)) & 1)
# define SET_MARK_BIT(x) (x = (((int) (x)) | 1)) # define SET_MARK_BIT(x) (x = (((int) (x)) | 1))
# define RESET_MARK_BIT(x) (x = (((int) (x)) & (~1))) # define RESET_MARK_BIT(x) (x = (((int) (x)) & (~1)))
# define GET_FORWARD_ADDRESS(x) (((int) (x)) & (~1)) // since last bit is used as mark-bit and due to correct alignment we can expect that last bit doesn't influence address (it should always be zero) # define GET_FORWARD_ADDRESS(x) (((size_t) (x)) & (~1)) // since last bit is used as mark-bit and due to correct alignment we can expect that last bit doesn'test_small_tree_compaction influence address (it should always be zero)
# define SET_FORWARD_ADDRESS(x, addr) (x = (((int) (x)) | ((int) (addr)))) # define SET_FORWARD_ADDRESS(x, addr) (x = (GET_MARK_BIT(x) | ((int) (addr))))
# define EXTRA_ROOM_HEAP_COEFFICIENT 2 // TODO: tune this parameter # define EXTRA_ROOM_HEAP_COEFFICIENT 2 // TODO: tune this parameter
#ifdef DEBUG_VERSION
# define MINIMUM_HEAP_CAPACITY (1<<8) // TODO: tune this parameter # define MINIMUM_HEAP_CAPACITY (1<<8) // TODO: tune this parameter
#else
# define MINIMUM_HEAP_CAPACITY (1<<8) // TODO: tune this parameter
#endif
#include <stddef.h> #include <stddef.h>
#include <stdbool.h> #include <stdbool.h>
#include "runtime_common.h" #include "runtime_common.h"
// this flag makes GC behavior a bit different for testing purposes.
#define DEBUG_VERSION
typedef enum { ARRAY, CLOSURE, STRING, SEXP } lama_type; typedef enum { ARRAY, CLOSURE, STRING, SEXP } lama_type;
typedef struct { typedef struct {
@ -53,27 +57,37 @@ void* gc_alloc(size_t);
// takes number of words as a parameter // takes number of words as a parameter
void *gc_alloc_on_existing_heap(size_t); void *gc_alloc_on_existing_heap(size_t);
void collect(); // specific for mark-and-compact_phase gc
// specific for mark-and-compact gc
void mark(void *obj); void mark(void *obj);
void mark_phase(void);
// written in ASM, scans stack for pointers to the heap and starts marking process
extern void __gc_root_scan_stack(void); // TODO: write without ASM, since it is absolutely not necessary
// marks each pointer from extra roots
void scan_extra_roots(void);
#ifndef DEBUG_VERSION
// marks each valid pointer from global area
void scan_global_area(void);
#endif
// takes number of words that are required to be allocated somewhere on the heap // takes number of words that are required to be allocated somewhere on the heap
void compact(size_t additional_size); void compact_phase(size_t additional_size);
// specific for Lisp-2 algorithm // specific for Lisp-2 algorithm
size_t compute_locations(); size_t compute_locations();
void update_references(memory_chunk *); void update_references(memory_chunk *);
void physically_relocate(memory_chunk *); void physically_relocate(memory_chunk *);
// written in ASM // written in ASM
extern void __gc_init (void); // MANDATORY TO CALL BEFORE ANY INTERACTION WITH GC (apart from cases where we are working with virtual stack as happens in tests) extern void __gc_init (void); // MANDATORY TO CALL BEFORE ANY INTERACTION WITH GC (apart from cases where we are working with virtual stack as happens in tests)
extern void __init (void); // should be called before interaction with GC in case of using in tests with virtual stack, otherwise it is automatically invoked by __gc_init
extern void __shutdown (void); // mostly useful for tests but basically you want to call this in case you want to deallocate all object allocated via GC
// written in ASM
extern void __pre_gc (void); extern void __pre_gc (void);
// written in ASM
extern void __post_gc (void); extern void __post_gc (void);
extern void __gc_root_scan_stack(void); // TODO: write without ASM, since it is absolutely not necessary
// invoked from ASM // invoked from ASM
extern void gc_test_and_mark_root(size_t ** root); extern void gc_test_and_mark_root(size_t ** root);
inline bool is_valid_heap_pointer(const size_t *); inline bool is_valid_heap_pointer(const size_t *);
inline bool is_valid_pointer(const size_t *);
void clear_extra_roots (void); void clear_extra_roots (void);
@ -86,8 +100,11 @@ void pop_extra_root (void ** p);
#ifdef DEBUG_VERSION #ifdef DEBUG_VERSION
// test-only function, these pointer parameters are just a fancy way to return two values at a time // makes a snapshot of current objects in heap (both alive and dead), writes these ids to object_ids_buf,
void objects_snapshot(void *objects_ptr, size_t objects_cnt); // returns number of ids dumped
// object_ids_buf is pointer to area preallocated by user for dumping ids of objects in heap
// object_ids_buf_size is in WORDS, NOT BYTES
size_t objects_snapshot(int *object_ids_buf, size_t object_ids_buf_size);
// essential function to mock program stack // essential function to mock program stack
void set_stack(size_t stack_top, size_t stack_bottom); void set_stack(size_t stack_top, size_t stack_bottom);
@ -100,11 +117,15 @@ void set_extra_roots(size_t extra_roots_size, void** extra_roots_ptr);
/* Utility functions */ /* Utility functions */
// accepts pointer to the start of the region and to the end of the region
// scans it and if it meets a pointer, it should be modified in according to forward address
void scan_and_fix_region(memory_chunk *old_heap, void *start, void *end);
// takes a pointer to an object content as an argument, returns forwarding address // takes a pointer to an object content as an argument, returns forwarding address
size_t get_forward_address(void *obj); size_t get_forward_address(void *obj);
// takes a pointer to an object content as an argument, sets forwarding address to value 'addr' // takes a pointer to an object content as an argument, sets forwarding address to value 'addr'
size_t set_forward_address(void *obj, size_t addr); void set_forward_address(void *obj, size_t addr);
// takes a pointer to an object content as an argument, returns whether this object was marked as live // takes a pointer to an object content as an argument, returns whether this object was marked as live
bool is_marked(void *obj); bool is_marked(void *obj);
@ -139,8 +160,8 @@ size_t string_size(size_t len);
// TODO: ask if it is actually so? number of captured elements is actually sz-1 and 1 extra word is code ptr? // TODO: ask if it is actually so? number of captured elements is actually sz-1 and 1 extra word is code ptr?
// returns number of bytes that are required to allocate closure with 'sz-1' captured values (header included) // returns number of bytes that are required to allocate closure with 'sz-1' captured values (header included)
size_t closure_size(size_t sz); size_t closure_size(size_t sz);
// returns number of bytes that are required to allocate s-expression with 'sz' fields (header included) // returns number of bytes that are required to allocate s-expression with 'members' fields (header included)
size_t sexp_size(size_t sz); size_t sexp_size(size_t members);
// returns an iterator over object fields, obj is ptr to object header // returns an iterator over object fields, obj is ptr to object header
// (in case of s-exp, it is mandatory that obj ptr is very beginning of the object, // (in case of s-exp, it is mandatory that obj ptr is very beginning of the object,
@ -161,4 +182,9 @@ void* get_obj_header_ptr(void *ptr, lama_type type);
void* get_object_content_ptr(void *header_ptr); void* get_object_content_ptr(void *header_ptr);
void* get_end_of_obj(void *header_ptr); void* get_end_of_obj(void *header_ptr);
void *alloc_string(int len);
void *alloc_array(int len);
void *alloc_sexp(int members);
void *alloc_closure(int captured);
#endif #endif

9
runtime/gc_runtime.s
View file

@ -17,7 +17,8 @@ __gc_stack_top: .long 0
.extern gc_test_and_copy_root .extern gc_test_and_copy_root
.text .text
__gc_init: movl %ebp, __gc_stack_bottom __gc_init:
movl %ebp, __gc_stack_bottom
addl $4, __gc_stack_bottom addl $4, __gc_stack_bottom
call __init call __init
ret ret
@ -60,7 +61,9 @@ __gc_root_scan_stack:
pushl %ebx pushl %ebx
pushl %edx pushl %edx
movl __gc_stack_top, %eax movl __gc_stack_top, %eax
jmp next // jmp next
cmpl %eax, __gc_stack_bottom
jb returnn
loop: loop:
movl (%eax), %ebx movl (%eax), %ebx
@ -106,7 +109,7 @@ gc_run_t:
next: next:
addl $4, %eax addl $4, %eax
cmpl %eax, __gc_stack_bottom cmpl %eax, __gc_stack_bottom
jne loop jnb loop
returnn: returnn:
movl $0, %eax movl $0, %eax
popl %edx popl %edx

605
runtime/runtime.c
View file

@ -13,12 +13,6 @@
//# define DEBUG_PRINT 1 //# define DEBUG_PRINT 1
/* GC memory_chunk structure and data; declared here in order to allow debug print */
static memory_chunk from_space;
static memory_chunk to_space;
size_t *current;
/* end */
# ifdef __ENABLE_GC__ # ifdef __ENABLE_GC__
/* GC extern invariant for built-in functions */ /* GC extern invariant for built-in functions */
@ -66,7 +60,7 @@ void Lassert (void *f, char *s, ...) {
do if (!UNBOXED(x) && TAG(TO_DATA(x)->data_header) \ do if (!UNBOXED(x) && TAG(TO_DATA(x)->data_header) \
!= STRING_TAG) failure ("string value expected in %s\n", memo); while (0) != STRING_TAG) failure ("string value expected in %s\n", memo); while (0)
extern void* alloc (size_t); //extern void* alloc (size_t);
extern void* Bsexp (int n, ...); extern void* Bsexp (int n, ...);
extern int LtagHash (char*); extern int LtagHash (char*);
@ -224,12 +218,8 @@ int Ls__Infix_37 (void *p, void *q) {
} }
extern int Llength (void *p) { extern int Llength (void *p) {
data *a = (data*) BOX (NULL);
ASSERT_BOXED(".length", p); ASSERT_BOXED(".length", p);
return BOX(obj_size_row_ptr(p));
a = TO_DATA(p);
return BOX(LEN(a->data_header));
} }
static char* chars = "_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'"; static char* chars = "_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'";
@ -373,7 +363,6 @@ static void printValue (void *p) {
for (i = 0; i < LEN(a->data_header); i++) { for (i = 0; i < LEN(a->data_header); i++) {
if (i) printValue ((void*)((int*) a->contents)[i]); if (i) printValue ((void*)((int*) a->contents)[i]);
else printStringBuf ("0x%x", (void*)((int*) a->contents)[i]); else printStringBuf ("0x%x", (void*)((int*) a->contents)[i]);
if (i != LEN(a->data_header) - 1) printStringBuf (", "); if (i != LEN(a->data_header) - 1) printStringBuf (", ");
} }
printStringBuf (">"); printStringBuf (">");
@ -397,9 +386,7 @@ static void printValue (void *p) {
if (strcmp (tag, "cons") == 0) { if (strcmp (tag, "cons") == 0) {
data *b = a; data *b = a;
printStringBuf ("{"); printStringBuf ("{");
while (LEN(a->data_header)) { while (LEN(a->data_header)) {
printValue ((void*)((int*) b->contents)[0]); printValue ((void*)((int*) b->contents)[0]);
b = (data*)((int*) b->contents)[1]; b = (data*)((int*) b->contents)[1];
@ -409,7 +396,6 @@ static void printValue (void *p) {
} }
else break; else break;
} }
printStringBuf ("}"); printStringBuf ("}");
} }
else { else {
@ -513,11 +499,9 @@ extern void* Lsubstring (void *subj, int p, int l) {
__pre_gc (); __pre_gc ();
push_extra_root (&subj); push_extra_root (&subj);
r = (data*) alloc (ll + 1 + sizeof (int)); r = (data*) alloc_string(ll);
pop_extra_root (&subj); pop_extra_root (&subj);
r->data_header = STRING_TAG | (ll << 3);
strncpy (r->contents, (char*) subj + pp, ll); strncpy (r->contents, (char*) subj + pp, ll);
__post_gc (); __post_gc ();
@ -532,7 +516,7 @@ extern void* Lsubstring (void *subj, int p, int l) {
extern struct re_pattern_buffer *Lregexp (char *regexp) { extern struct re_pattern_buffer *Lregexp (char *regexp) {
regex_t *b = (regex_t*) malloc (sizeof (regex_t)); regex_t *b = (regex_t*) malloc (sizeof (regex_t));
/* printf ("regexp: %s,\t%x\n", regexp, b); */ /* printf ("regexp: %s,\test_small_tree_compaction%x\n", regexp, b); */
memset (b, 0, sizeof (regex_t)); memset (b, 0, sizeof (regex_t));
@ -597,13 +581,21 @@ void *Lclone (void *p) {
break; break;
case ARRAY_TAG: case ARRAY_TAG:
#ifdef DEBUG_PRINT
print_indent ();
printf ("Lclone: array &p=%p p=%p ebp=%p\n", &p, p, ebp); fflush (stdout);
#endif
obj = (data *) alloc_array(l);
memcpy(obj, TO_DATA(p), array_size(l));
res = (void *) obj->contents;
break;
case CLOSURE_TAG: case CLOSURE_TAG:
#ifdef DEBUG_PRINT #ifdef DEBUG_PRINT
print_indent (); print_indent ();
printf ("Lclone: closure or array &p=%p p=%p ebp=%p\n", &p, p, ebp); fflush (stdout); printf ("Lclone: closure &p=%p p=%p ebp=%p\n", &p, p, ebp); fflush (stdout);
#endif #endif
obj = (data*) alloc (sizeof(int) * (l+1)); obj = (data *) alloc_closure(l);
memcpy (obj, TO_DATA(p), sizeof(int) * (l+1)); memcpy (obj, TO_DATA(p), closure_size(l));
res = (void*) (obj->contents); res = (void*) (obj->contents);
break; break;
@ -611,8 +603,8 @@ void *Lclone (void *p) {
#ifdef DEBUG_PRINT #ifdef DEBUG_PRINT
print_indent (); printf ("Lclone: sexp\n"); fflush (stdout); print_indent (); printf ("Lclone: sexp\n"); fflush (stdout);
#endif #endif
sobj = (sexp*) alloc (sizeof(int) * (l+2)); sobj = (sexp*) alloc_sexp(l);
memcpy (sobj, TO_SEXP(p), sizeof(int) * (l+2)); memcpy (sobj, TO_SEXP(p), sexp_size(l));
res = (void*) sobj->contents.contents; res = (void*) sobj->contents.contents;
break; break;
@ -806,9 +798,7 @@ extern void* LmakeArray (int length) {
__pre_gc (); __pre_gc ();
n = UNBOX(length); n = UNBOX(length);
r = (data*) alloc (sizeof(int) * (n+1)); r = (data*) alloc_array(n);
r->data_header = ARRAY_TAG | (n << 3);
p = (int*) r->contents; p = (int*) r->contents;
while (n--) *p++ = BOX(0); while (n--) *p++ = BOX(0);
@ -826,9 +816,7 @@ extern void* LmakeString (int length) {
__pre_gc () ; __pre_gc () ;
r = (data*) alloc (n + 1 + sizeof (int)); r = (data*) alloc_string(n); // '\0' in the end of the string is taken into account
r->data_header = STRING_TAG | (n << 3);
__post_gc(); __post_gc();
@ -837,7 +825,7 @@ extern void* LmakeString (int length) {
extern void* Bstring (void *p) { extern void* Bstring (void *p) {
int n = strlen (p); int n = strlen (p);
data *s = NULL; void *s = NULL;
__pre_gc (); __pre_gc ();
#ifdef DEBUG_PRINT #ifdef DEBUG_PRINT
@ -852,7 +840,7 @@ extern void* Bstring (void *p) {
print_indent (); print_indent ();
printf ("\tBstring: call strncpy: %p %p %p %i\n", &p, p, s, n); fflush(stdout); printf ("\tBstring: call strncpy: %p %p %p %i\n", &p, p, s, n); fflush(stdout);
#endif #endif
strncpy ((char*)s, p, n + 1); strncpy ((char*)s, p, n + 1); // +1 because of '\0' in the end of C-strings
#ifdef DEBUG_PRINT #ifdef DEBUG_PRINT
print_indent (); print_indent ();
printf ("\tBstring: ends\n"); fflush(stdout); printf ("\tBstring: ends\n"); fflush(stdout);
@ -921,9 +909,8 @@ extern void* Bclosure (int bn, void *entry, ...) {
push_extra_root ((void**)argss); push_extra_root ((void**)argss);
} }
r = (data*) alloc (sizeof(int) * (n+2)); r = (data*) alloc_closure(n + 1);
r->data_header = CLOSURE_TAG | ((n + 1) << 3);
((void**) r->contents)[0] = entry; ((void**) r->contents)[0] = entry;
va_start(args, entry); va_start(args, entry);
@ -963,9 +950,7 @@ extern void* Barray (int bn, ...) {
indent++; print_indent (); indent++; print_indent ();
printf ("Barray: create n = %d\n", n); fflush(stdout); printf ("Barray: create n = %d\n", n); fflush(stdout);
#endif #endif
r = (data*) alloc (sizeof(int) * (n+1)); r = (data*) alloc_array(n);
r->data_header = ARRAY_TAG | (n << 3);
va_start(args, bn); va_start(args, bn);
@ -983,6 +968,10 @@ extern void* Barray (int bn, ...) {
return r->contents; return r->contents;
} }
#ifdef DEBUG_VERSION
extern memory_chunk heap;
#endif
extern void* Bsexp (int bn, ...) { extern void* Bsexp (int bn, ...) {
va_list args; va_list args;
int i; int i;
@ -998,17 +987,22 @@ extern void* Bsexp (int bn, ...) {
indent++; print_indent (); indent++; print_indent ();
printf("Bsexp: allocate %zu!\n",sizeof(int) * (n+1)); fflush (stdout); printf("Bsexp: allocate %zu!\n",sizeof(int) * (n+1)); fflush (stdout);
#endif #endif
r = (sexp*) alloc (sizeof(int) * (n+1)); int fields_cnt = n - 1;
r = (sexp*) alloc_sexp(fields_cnt);
d = &(r->contents); d = &(r->contents);
r->tag = 0; r->tag = 0;
d->data_header = SEXP_TAG | ((n - 1) << 3);
va_start(args, bn); va_start(args, bn);
for (i=0; i<n-1; i++) { for (i=0; i<n-1; i++) {
ai = va_arg(args, int); ai = va_arg(args, int);
#ifdef DEBUG_VERSION
if (!UNBOXED(ai)) {
assert(is_valid_heap_pointer((size_t *) ai));
}
#endif
p = (size_t*) ai; p = (size_t*) ai;
((int*)d->contents)[i] = ai; ((int*)d->contents)[i] = ai;
} }
@ -1039,7 +1033,7 @@ extern int Btag (void *d, int t, int n) {
return BOX(TAG(r->data_header) == SEXP_TAG && TO_SEXP(d)->tag == UNBOX(t) && LEN(r->data_header) == UNBOX(n)); return BOX(TAG(r->data_header) == SEXP_TAG && TO_SEXP(d)->tag == UNBOX(t) && LEN(r->data_header) == UNBOX(n));
#else #else
return BOX(TAG(r->data_header) == SEXP_TAG && return BOX(TAG(r->data_header) == SEXP_TAG &&
GET_SEXP_TAG(TO_SEXP(d)->data_header) == UNBOX(t) && LEN(r->data_header) == UNBOX(n)); GET_SEXP_TAG(TO_SEXP(d)->data_header) == UNBOX(test_small_tree_compaction) && LEN(r->data_header) == UNBOX(n));
#endif #endif
} }
} }
@ -1164,15 +1158,13 @@ extern void* /*Lstrcat*/ Li__Infix_4343 (void *a, void *b) {
push_extra_root (&a); push_extra_root (&a);
push_extra_root (&b); push_extra_root (&b);
d = (data *) alloc (sizeof(int) + LEN(da->data_header) + LEN(db->data_header) + 1); d = alloc_string(LEN(da->data_header) + LEN(db->data_header));
pop_extra_root (&b); pop_extra_root (&b);
pop_extra_root (&a); pop_extra_root (&a);
da = TO_DATA(a); da = TO_DATA(a);
db = TO_DATA(b); db = TO_DATA(b);
d->data_header = STRING_TAG | ((LEN(da->data_header) + LEN(db->data_header)) << 3);
strncpy (d->contents , da->contents, LEN(da->data_header)); strncpy (d->contents , da->contents, LEN(da->data_header));
strncpy (d->contents + LEN(da->data_header), db->contents, LEN(db->data_header)); strncpy (d->contents + LEN(da->data_header), db->contents, LEN(db->data_header));
@ -1214,7 +1206,7 @@ extern void* LgetEnv (char *var) {
void *s; void *s;
if (e == NULL) if (e == NULL)
return BOX(0); // TODO add (void*) cast? return (void*) BOX(0); // TODO add (void*) cast?
__pre_gc (); __pre_gc ();
@ -1346,9 +1338,9 @@ extern void* Lfexists (char *fname) {
f = fopen (fname, "r"); f = fopen (fname, "r");
if (f) return BOX(1); // (void*) cast? if (f) return (void*) BOX(1); // (void*) cast?
return BOX(0); // (void*) cast? return (void*) BOX(0); // (void*) cast?
} }
extern void* Lfst (void *v) { extern void* Lfst (void *v) {
@ -1457,520 +1449,3 @@ extern void LenableGC () {
extern void LdisableGC () { extern void LdisableGC () {
enable_GC = 0; enable_GC = 0;
} }
extern const size_t __start_custom_data, __stop_custom_data;
# ifdef __ENABLE_GC__
extern void __gc_init ();
# else
# define __gc_init __gc_init_subst
void __gc_init_subst () {}
# endif
extern void __gc_root_scan_stack ();
/* ======================================== */
/* Mark-and-copy */
/* ======================================== */
//static size_t SPACE_SIZE = 16;
static size_t SPACE_SIZE = 256 * 1024 * 1024;
// static size_t SPACE_SIZE = 128;
// static size_t SPACE_SIZE = 1024 * 1024;
static int free_pool (memory_chunk * p) {
size_t *a = p->begin, b = p->size;
p->begin = NULL;
p->size = 0;
p->end = NULL;
p->current = NULL;
return munmap((void *)a, b);
}
static void init_to_space (int flag) {
size_t space_size = 0;
if (flag) SPACE_SIZE = SPACE_SIZE << 1;
space_size = SPACE_SIZE * sizeof(size_t);
to_space.begin = mmap (NULL, space_size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_32BIT, -1, 0);
if (to_space.begin == MAP_FAILED) {
perror ("EROOR: init_to_space: mmap failed\n");
exit (1);
}
to_space.current = to_space.begin;
to_space.end = to_space.begin + SPACE_SIZE;
to_space.size = SPACE_SIZE;
}
static void gc_swap_spaces (void) {
#ifdef DEBUG_PRINT
indent++; print_indent ();
printf ("gc_swap_spaces\n"); fflush (stdout);
#endif
free_pool (&from_space);
from_space.begin = to_space.begin;
from_space.current = current;
from_space.end = to_space.end;
from_space.size = to_space.size;
to_space.begin = NULL;
to_space.current = NULL;
to_space.end = NULL;
to_space.size = 0;
#ifdef DEBUG_PRINT
indent--;
#endif
}
# define IS_VALID_HEAP_POINTER(p)\
(!UNBOXED(p) && \
(size_t)from_space.begin <= (size_t)p && \
(size_t)from_space.end > (size_t)p)
# define IN_PASSIVE_SPACE(p) \
((size_t)to_space.begin <= (size_t)p && \
(size_t)to_space.end > (size_t)p)
# define IS_FORWARD_PTR(p) \
(!UNBOXED(p) && IN_PASSIVE_SPACE(p))
int is_valid_heap_pointer (void *p) {
return IS_VALID_HEAP_POINTER(p);
}
extern size_t * gc_copy (size_t *obj);
static void copy_elements (size_t *where, size_t *from, int len) {
int i = 0;
void * p = NULL;
#ifdef DEBUG_PRINT
indent++; print_indent ();
printf ("copy_elements: start; len = %d\n", len); fflush (stdout);
#endif
for (i = 0; i < len; i++) {
size_t elem = from[i];
if (!IS_VALID_HEAP_POINTER(elem)) {
*where = elem;
where++;
#ifdef DEBUG_PRINT
print_indent ();
printf ("copy_elements: copy NON ptr: %zu %p \n", elem, elem); fflush (stdout);
#endif
}
else {
#ifdef DEBUG_PRINT
print_indent ();
printf ("copy_elements: fix element: %p -> %p\n", elem, *where);
fflush (stdout);
#endif
p = gc_copy ((size_t*) elem);
*where = (size_t) p;
where ++;
}
#ifdef DEBUG_PRINT
print_indent ();
printf ("copy_elements: iteration end: where = %p, *where = %p, i = %d, \
len = %d\n", where, *where, i, len); fflush (stdout);
#endif
}
#ifdef DEBUG_PRINT
print_indent ();
printf ("\tcopy_elements: end\n"); fflush (stdout);
indent--;
#endif
}
static int extend_spaces (void) {
void *p = (void *) BOX (NULL);
size_t old_space_size = SPACE_SIZE * sizeof(size_t),
new_space_size = (SPACE_SIZE << 1) * sizeof(size_t);
p = mremap(to_space.begin, old_space_size, new_space_size, 0);
#ifdef DEBUG_PRINT
indent++; print_indent ();
#endif
if (p == MAP_FAILED) {
#ifdef DEBUG_PRINT
print_indent ();
printf ("extend: extend_spaces: mremap failed\n"); fflush (stdout);
#endif
return 1;
}
#ifdef DEBUG_PRINT
print_indent ();
printf ("extend: %p %p %p %p\n", p, to_space.begin, to_space.end, current);
fflush (stdout);
indent--;
#endif
to_space.end += SPACE_SIZE;
SPACE_SIZE = SPACE_SIZE << 1;
to_space.size = SPACE_SIZE;
return 0;
}
extern size_t * gc_copy (size_t *obj) {
data *d = TO_DATA(obj);
sexp *s = NULL;
size_t *copy = NULL;
int i = 0;
#ifdef DEBUG_PRINT
int len1, len2, len3;
void * objj;
void * newobjj = (void*)current;
indent++; print_indent ();
printf ("gc_copy: %p cur = %p starts\n", obj, current);
fflush (stdout);
#endif
if (!IS_VALID_HEAP_POINTER(obj)) {
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc_copy: invalid ptr: %p\n", obj); fflush (stdout);
indent--;
#endif
return obj;
}
if (!IN_PASSIVE_SPACE(current) && current != to_space.end) {
#ifdef DEBUG_PRINT
print_indent ();
printf("ERROR: gc_copy: out-of-space %p %p %p\n",
current, to_space.begin, to_space.end);
fflush(stdout);
#endif
perror("ERROR: gc_copy: out-of-space\n");
exit (1);
}
if (IS_FORWARD_PTR(d->data_header)) {
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc_copy: IS_FORWARD_PTR: return! %p -> %p\n", obj, (size_t *) d->data_header);
fflush(stdout);
indent--;
#endif
return (size_t *) d->data_header;
}
copy = current;
#ifdef DEBUG_PRINT
objj = d;
#endif
switch (TAG(d->data_header)) {
case CLOSURE_TAG:
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc_copy:closure_tag; len = %zu\n", LEN(d->data_header)); fflush (stdout);
#endif
i = LEN(d->data_header);
// current += LEN(d->data_header) + 1;
// current += ((LEN(d->data_header) + 1) * sizeof(int) -1) / sizeof(size_t) + 1;
current += i+1;
*copy = d->data_header;
copy++;
d->data_header = (int) copy;
copy_elements (copy, obj, i);
break;
case ARRAY_TAG:
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc_copy:array_tag; len = %zu\n", LEN(d->data_header)); fflush (stdout);
#endif
current += ((LEN(d->data_header) + 1) * sizeof (int) - 1) / sizeof (size_t) + 1;
*copy = d->data_header;
copy++;
i = LEN(d->data_header);
d->data_header = (int) copy;
copy_elements (copy, obj, i);
break;
case STRING_TAG:
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc_copy:string_tag; len = %d\n", LEN(d->data_header) + 1); fflush (stdout);
#endif
current += (LEN(d->data_header) + sizeof(int)) / sizeof(size_t) + 1;
*copy = d->data_header;
copy++;
d->data_header = (int) copy;
strcpy ((char*)&copy[0], (char*) obj);
break;
case SEXP_TAG :
s = TO_SEXP(obj);
#ifdef DEBUG_PRINT
objj = s;
len1 = LEN(s->contents.data_header);
len2 = LEN(s->data_header);
len3 = LEN(d->data_header);
print_indent ();
printf ("gc_copy:sexp_tag; len1 = %li, len2=%li, len3 = %li\n",
len1, len2, len3);
fflush (stdout);
#endif
i = LEN(s->contents.data_header);
current += i + 2;
*copy = s->tag;
copy++;
*copy = d->data_header;
copy++;
d->data_header = (int) copy;
copy_elements (copy, obj, i);
break;
default:
#ifdef DEBUG_PRINT
print_indent ();
printf ("ERROR: gc_copy: weird data_header: %p", TAG(d->data_header)); fflush (stdout);
indent--;
#endif
perror ("ERROR: gc_copy: weird data_header");
exit (1);
return (obj);
}
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc_copy: %p(%p) -> %p (%p); new-current = %p\n",
obj, objj, copy, newobjj, current);
fflush (stdout);
indent--;
#endif
return copy;
}
extern void gc_test_and_copy_root (size_t ** root) {
#ifdef DEBUG_PRINT
indent++;
#endif
if (IS_VALID_HEAP_POINTER(*root)) {
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc_test_and_copy_root: root %p top=%p bot=%p *root %p \n", root, __gc_stack_top, __gc_stack_bottom, *root);
fflush (stdout);
#endif
*root = gc_copy (*root);
}
#ifdef DEBUG_PRINT
else {
print_indent ();
printf ("gc_test_and_copy_root: INVALID HEAP POINTER root %p *root %p\n", root, *root);
fflush (stdout);
}
indent--;
#endif
}
extern void gc_root_scan_data (void) {
size_t * p = (size_t*)&__start_custom_data;
while (p < (size_t*)&__stop_custom_data) {
gc_test_and_copy_root ((size_t**)p);
p++;
}
}
static void* gc (size_t size) {
if (! enable_GC) {
Lfailure ("GC disabled");
}
current = to_space.begin;
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc: current:%p; to_space.b =%p; to_space.e =%p; \
f_space.b = %p; f_space.e = %p; __gc_stack_top=%p; __gc_stack_bottom=%p\n",
current, to_space.begin, to_space.end, from_space.begin, from_space.end,
__gc_stack_top, __gc_stack_bottom);
fflush (stdout);
#endif
gc_root_scan_data ();
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc: data is scanned\n"); fflush (stdout);
#endif
__gc_root_scan_stack ();
for (int i = 0; i < extra_roots.current_free; i++) {
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc: extra_root № %i: %p %p\n", i, extra_roots.roots[i],
(size_t*) extra_roots.roots[i]);
fflush (stdout);
#endif
gc_test_and_copy_root ((size_t**)extra_roots.roots[i]);
}
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc: no more extra roots\n"); fflush (stdout);
#endif
if (!IN_PASSIVE_SPACE(current)) {
printf ("gc: ASSERT: !IN_PASSIVE_SPACE(current) to_begin = %p to_end = %p \
current = %p\n", to_space.begin, to_space.end, current);
fflush (stdout);
perror ("ASSERT: !IN_PASSIVE_SPACE(current)\n");
exit (1);
}
while (current + size >= to_space.end) {
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc: pre-extend_spaces : %p %zu %p \n", current, size, to_space.end);
fflush (stdout);
#endif
if (extend_spaces ()) {
gc_swap_spaces ();
init_to_space (1);
return gc (size);
}
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc: post-extend_spaces: %p %zu %p \n", current, size, to_space.end);
fflush (stdout);
#endif
}
assert (IN_PASSIVE_SPACE(current));
assert (current + size < to_space.end);
gc_swap_spaces ();
from_space.current = current + size;
#ifdef DEBUG_PRINT
print_indent ();
printf ("gc: end: (allocate!) return %p; from_space.current %p; \
from_space.end %p \n\n",
current, from_space.current, from_space.end);
fflush (stdout);
indent--;
#endif
return (void *) current;
}
#ifdef DEBUG_PRINT
static void printFromSpace (void) {
size_t * cur = from_space.begin, *tmp = NULL;
data * d = NULL;
sexp * s = NULL;
size_t len = 0;
size_t elem_number = 0;
printf ("\nHEAP SNAPSHOT\n===================\n");
printf ("f_begin = %p, f_end = %p,\n", from_space.begin, from_space.end);
while (cur < from_space.current) {
printf ("data at %p", cur);
d = (data *) cur;
switch (TAG(d->data_header)) {
case STRING_TAG:
printf ("(=>%p): STRING\n\t%s; len = %i %zu\n",
d->contents, d->contents,
LEN(d->data_header), LEN(d->data_header) + 1 + sizeof(int));
fflush (stdout);
len = (LEN(d->data_header) + sizeof(int)) / sizeof(size_t) + 1;
break;
case CLOSURE_TAG:
printf ("(=>%p): CLOSURE\n\t", d->contents);
len = LEN(d->data_header);
for (int i = 0; i < len; i++) {
int elem = ((int*)d->contents)[i];
if (UNBOXED(elem)) printf ("%d ", elem);
else printf ("%p ", elem);
}
len += 1;
printf ("\n");
fflush (stdout);
break;
case ARRAY_TAG:
printf ("(=>%p): ARRAY\n\t", d->contents);
len = LEN(d->data_header);
for (int i = 0; i < len; i++) {
int elem = ((int*)d->contents)[i];
if (UNBOXED(elem)) printf ("%d ", elem);
else printf ("%p ", elem);
}
len += 1;
printf ("\n");
fflush (stdout);
break;
case SEXP_TAG:
s = (sexp *) d;
d = (data *) &(s->contents);
char * data_header = de_hash (GET_SEXP_TAG(s->data_header));
printf ("(=>%p): SEXP\n\tdata_header(%s) ", s->contents.contents, data_header);
len = LEN(d->data_header);
tmp = (s->contents.contents);
for (int i = 0; i < len; i++) {
int elem = ((int*)tmp)[i];
if (UNBOXED(elem)) printf ("%d ", UNBOX(elem));
else printf ("%p ", elem);
}
len += 2;
printf ("\n");
fflush (stdout);
break;
case 0:
printf ("\nprintFromSpace: end: %zu elements\n===================\n\n",
elem_number);
return;
default:
printf ("\nprintFromSpace: ERROR: bad data_header %d", TAG(d->data_header));
perror ("\nprintFromSpace: ERROR: bad data_header");
fflush (stdout);
exit (1);
}
cur += len;
printf ("len = %zu, new cur = %p\n", len, cur);
elem_number++;
}
printf ("\nprintFromSpace: end: the whole space is printed:\
%zu elements\n===================\n\n", elem_number);
fflush (stdout);
}
#endif
#ifdef __ENABLE_GC__
// alloc: allocates `size` bytes in heap
extern void * alloc (size_t size) {
void * p = (void*)BOX(NULL);
size = (size - 1) / sizeof(size_t) + 1; // convert bytes to words
#ifdef DEBUG_PRINT
indent++; print_indent ();
printf ("alloc: current: %p %zu words!", from_space.current, size);
fflush (stdout);
#endif
if (from_space.current + size < from_space.end) {
p = (void*) from_space.current;
from_space.current += size;
#ifdef DEBUG_PRINT
print_indent ();
printf (";new current: %p \n", from_space.current); fflush (stdout);
indent--;
#endif
return p;
}
init_to_space (0);
#ifdef DEBUG_PRINT
print_indent ();
printf ("alloc: call gc: %zu\n", size); fflush (stdout);
printFromSpace(); fflush (stdout);
p = gc (size);
print_indent ();
printf("alloc: gc END %p %p %p %p\n\n", from_space.begin,
from_space.end, from_space.current, p); fflush (stdout);
printFromSpace(); fflush (stdout);
indent--;
return p;
#else
return gc (size);
#endif
}
# endif

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#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "gc.h"
#include "runtime_common.h"
// function from runtime that maps string to int value
extern int LtagHash (char *s);
extern void* Bsexp (int n, ...);
extern void* Barray (int bn, ...);
extern void* Bstring (void*);
extern void* Bclosure (int bn, void *entry, ...);
extern size_t __gc_stack_top, __gc_stack_bottom;
void test_correct_structure_sizes(void) {
// something like induction base
assert((array_size(0) == get_header_size(ARRAY)));
assert((string_size(0) == get_header_size(STRING) + 1)); // +1 is because of '\0'
assert((sexp_size(0) == get_header_size(SEXP)));
assert((closure_size(0) == get_header_size(CLOSURE)));
// just check correctness for some small sizes
for (int k = 1; k < 20; ++k) {
assert((array_size(k) == get_header_size(ARRAY) + sizeof (int) * k));
assert((string_size(k) == get_header_size(STRING) + k + 1));
assert((sexp_size(k) == get_header_size(SEXP) + sizeof (int) * k));
assert((closure_size(k) == get_header_size(CLOSURE) + sizeof (int) * k));
}
}
void no_gc_tests(void) {
test_correct_structure_sizes();
}
// unfortunately there is no generic function pointer that can hold pointer to function with arbitrary signature
extern size_t call_runtime_function(void *virt_stack_pointer, void *function_pointer, size_t num_args, ...);
#include "virt_stack.h"
virt_stack* init_test() {
__init();
virt_stack *st = vstack_create();
vstack_init(st);
__gc_stack_bottom = (size_t) vstack_top(st);
return st;
}
void cleanup_test(virt_stack *st) {
vstack_destruct(st);
__shutdown();
}
void force_gc_cycle(virt_stack *st) {
__gc_stack_top = (size_t) vstack_top(st);
gc_alloc(0);
__gc_stack_top = 0;
}
void test_simple_string_alloc(void) {
virt_stack *st = init_test();
for (int i = 0; i < 5; ++i) {
vstack_push(st, BOX(i));
}
vstack_push(st, call_runtime_function(vstack_top(st), Bstring, 1, "abc"));
const int N = 10;
int ids[N];
size_t alive = objects_snapshot(ids, N);
assert((alive == 1));
cleanup_test(st);
}
void test_simple_array_alloc(void) {
virt_stack* st = init_test();
// allocate array [ BOX(1) ] and push it onto the stack
vstack_push(st, call_runtime_function(vstack_top(st), Barray, 2, BOX(1), BOX(1)));
const int N = 10;
int ids[N];
size_t alive = objects_snapshot(ids, N);
assert((alive == 1));
cleanup_test(st);
}
void test_simple_sexp_alloc(void) {
virt_stack* st = init_test();
// allocate sexp with one boxed field and push it onto the stack
// calling runtime function Bsexp(BOX(2), BOX(1), LtagHash("test"))
vstack_push(st, call_runtime_function(vstack_top(st), Bsexp, 3, BOX(2), BOX(1), LtagHash("test")));
const int N = 10;
int ids[N];
size_t alive = objects_snapshot(ids, N);
assert((alive == 1));
cleanup_test(st);
}
void test_simple_closure_alloc(void) {
virt_stack* st = init_test();
// allocate closure with boxed captured value and push it onto the stack
vstack_push(st, call_runtime_function(vstack_top(st), Bclosure, 3, BOX(1), NULL, BOX(1)));
const int N = 10;
int ids[N];
size_t alive = objects_snapshot(ids, N);
assert((alive == 1));
cleanup_test(st);
}
void test_single_object_allocation_with_collection_virtual_stack(void) {
virt_stack *st = init_test();
vstack_push(st, call_runtime_function(vstack_top(st), Bstring, 1, "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"));
const int N = 10;
int ids[N];
size_t alive = objects_snapshot(ids, N);
assert((alive == 1));
cleanup_test(st);
}
void test_garbage_is_reclaimed(void) {
virt_stack *st = init_test();
call_runtime_function(vstack_top(st), Bstring, 1, "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
force_gc_cycle(st);
const int N = 10;
int ids[N];
size_t alive = objects_snapshot(ids, N);
assert((alive == 0));
cleanup_test(st);
}
void test_alive_are_not_reclaimed(void) {
virt_stack *st = init_test();
vstack_push(st, call_runtime_function(vstack_top(st), Bstring, 1, "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"));
force_gc_cycle(st);
const int N = 10;
int ids[N];
size_t alive = objects_snapshot(ids, N);
assert((alive == 1));
cleanup_test(st);
}
void test_small_tree_compaction(void) {
virt_stack *st = init_test();
// this one will increase heap size
call_runtime_function(vstack_top(st), Bstring, 1, "aaaaaaaaaaaaaaaaaaaaaa");
size_t l = call_runtime_function(vstack_top(st), Bstring, 1, "left-s");
size_t r = call_runtime_function(vstack_top(st), Bstring, 1, "right-s");
vstack_push(st, call_runtime_function(vstack_top(st), Bsexp, 4, BOX(3), (size_t)l, (size_t) r, LtagHash("tree")));
force_gc_cycle(st);
const int SZ = 10;
int ids[SZ];
size_t alive = objects_snapshot(ids, SZ);
assert((alive == 3));
// check that order is indeed preserved
for (int i = 0; i < alive - 1; ++i) {
assert((ids[i] < ids[i + 1]));
}
cleanup_test(st);
}
extern size_t cur_id;
size_t generate_random_obj_forest(virt_stack *st, int cnt, int seed) {
srand(seed);
int cur_sz = 0;
size_t alive = 0;
while (cnt) {
--cnt;
if (cur_sz == 0) {
vstack_push(st, BOX(1));
++cur_sz;
continue;
}
size_t pos[2] = {rand() % vstack_size(st), rand() % vstack_size(st)};
size_t field[2];
for (int t = 0; t < 2; ++t) {
field[t] = vstack_kth_from_start(st, pos[t]);
}
size_t obj;
if (rand() % 2) {
obj = call_runtime_function(vstack_top(st), Bsexp, 4, BOX(3), field[0], field[1], LtagHash("test"));
} else {
obj = BOX(1);
}
// whether object is stored on stack
if (rand() % 2 != 0) {
vstack_push(st, obj);
if ((obj & 1) == 0) {
++alive;
}
}
++cur_sz;
}
force_gc_cycle(st);
return alive;
}
void run_stress_test_random_obj_forest(int seed) {
virt_stack *st = init_test();
const int SZ = 10000;
size_t expectedAlive = generate_random_obj_forest(st, SZ, seed);
int ids[SZ];
size_t alive = objects_snapshot(ids, SZ);
assert(alive == expectedAlive);
// check that order is indeed preserved
for (int i = 0; i < alive - 1; ++i) {
assert((ids[i] < ids[i + 1]));
}
cleanup_test(st);
}
int main(int argc, char ** argv) {
no_gc_tests();
test_simple_string_alloc();
test_simple_array_alloc();
test_simple_sexp_alloc();
test_simple_closure_alloc();
test_single_object_allocation_with_collection_virtual_stack();
test_garbage_is_reclaimed();
test_alive_are_not_reclaimed();
test_small_tree_compaction();
// stress test
for (int s = 0; s < 100; ++s) {
run_stress_test_random_obj_forest(s);
}
}

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# this is equivalent C-signature for this function
# size_t call_runtime_function(void *stack, void *func_ptr, int num_args, ...)
.globl call_runtime_function
.type call_runtime_function, @function
call_runtime_function:
pushl %ebp
movl %esp, %ebp
# store old stack pointer
movl %esp, %edi
# move esp to point to the virtual stack
movl 8(%ebp), %esp
# push arguments onto the stack
movl 16(%ebp), %ecx # num_args
test %ecx, %ecx
jz f_call # in case function doesn't have any parameters
leal 16(%ebp), %eax # pointer to value BEFORE first argument
leal (%eax,%ecx,4), %edx # pointer to last argument (right-to-left)
push_args_loop:
pushl (%edx)
subl $4, %edx
subl $1, %ecx
jnz push_args_loop
# call the function
f_call:
movl 12(%ebp), %eax
call *%eax
# restore the old stack pointer
movl %edi, %esp
# pop the old frame pointer and return
popl %ebp # epilogue
ret

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#include "virt_stack.h"
#include <malloc.h>
virt_stack *vstack_create() {
return malloc(sizeof (virt_stack));
}
void vstack_destruct(virt_stack *st) {
free(st);
}
void vstack_init(virt_stack *st) {
st->cur = RUNTIME_VSTACK_SIZE;
st->buf[st->cur] = 0;
}
void vstack_push(virt_stack *st, size_t value) {
if (st->cur == 0) {
assert(0);
}
--st->cur;
st->buf[st->cur] = value;
}
size_t vstack_pop(virt_stack *st) {
if (st->cur == RUNTIME_VSTACK_SIZE) {
assert(0);
}
size_t value = st->buf[st->cur];
++st->cur;
return value;
}
void* vstack_top(virt_stack *st) {
return st->buf + st->cur;
}
size_t vstack_size(virt_stack *st) {
return RUNTIME_VSTACK_SIZE - st->cur;
}
size_t vstack_kth_from_start(virt_stack *st, size_t k) {
assert(vstack_size(st) > k);
return st->buf[RUNTIME_VSTACK_SIZE - 1 - k];
}

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//
// Created by egor on 24.04.23.
//
#ifndef LAMA_RUNTIME_VIRT_STACK_H
#define LAMA_RUNTIME_VIRT_STACK_H
#define RUNTIME_VSTACK_SIZE 100000
#include <stddef.h>
#include <assert.h>
struct {
size_t buf[RUNTIME_VSTACK_SIZE + 1];
size_t cur;
} typedef virt_stack;
virt_stack *vstack_create();
void vstack_destruct(virt_stack *st);
void vstack_init(virt_stack *st);
void vstack_push(virt_stack *st, size_t value);
size_t vstack_pop(virt_stack *st);
void* vstack_top(virt_stack *st);
size_t vstack_size(virt_stack *st);
size_t vstack_kth_from_start(virt_stack *st, size_t k);
#endif //LAMA_RUNTIME_VIRT_STACK_H