Refactor into a GC library (gc.c and gc.h) and a test program (gc_test.c).
Also, allocate GC memory ranges dynamically during startup (gc_init()) rather than statically.
This commit is contained in:
parent
61b83a1293
commit
8db40406a0
22
Makefile
22
Makefile
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@ -1,18 +1,30 @@
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CFLAGS = -std=c99 -O2 -DNDEBUG
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CFLAGS = -std=c99
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all: gc
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ifeq ($(DEBUG),yes)
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CFLAGS += -g
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PROFILE = no
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dummy := $(shell $(MAKE) clean)
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else
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CFLAGS += -O2 -DNDEBUG
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endif
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all: gc_test
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.PHONY: all clean
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ifneq ($(PROFILE),no)
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CFLAGS += -fprofile-generate
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LDFLAGS += -fprofile-generate
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endif
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ifneq (,$(wildcard *.gcda))
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CFLAGS += -fprofile-use
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dummy := $(shell rm -f gc)
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dummy := $(shell rm -f gc_test *.o)
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endif
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clean:
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-rm -f gc gc.gcda gc.gcno
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-rm -f gc_test *.o *.gcda *.gcno
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gc: gc.c
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gc_test: gc_test.o gc.o
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gc_test.o: gc_test.c gc.h
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gc.o: gc.c gc.h
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244
gc.c
244
gc.c
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@ -1,5 +1,3 @@
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#include <sys/time.h>
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#include <assert.h>
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#include <inttypes.h>
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#include <stdbool.h>
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@ -8,115 +6,13 @@
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#include <string.h>
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#include <time.h>
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#ifndef NDEBUG
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# define debug(printf_args) ((void)printf printf_args)
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#else
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# define debug(printf_args) ((void)0)
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#endif
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#include "gc.h"
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typedef uintptr_t value_t;
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extern int gc_counter;
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extern int gc_ticks;
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/* NIL: 00000000 00000000 00000000 00000000 */
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/* Pair: aaaaaaaa aaaaaaaa aaaaaaaa aaaaaa00 (where aa... >= 1024) */
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/* Object: aaaaaaaa aaaaaaaa aaaaaaaa aaaaaa10 */
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/* Fixnum: snnnnnnn nnnnnnnn nnnnnnnn nnnnnnn1 */
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/* Special values (0 <= n < 1024) */
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/* These correspond to pairs within the first page of memory */
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#define SPECIAL_VALUE(n) ((value_t)(4*n))
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#define MAX_SPECIAL SPECIAL_VALUE(1023)
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#define NIL SPECIAL_VALUE(0)
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#define BROKEN_HEART SPECIAL_VALUE(1)
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#define TYPE_TAG_BOX SPECIAL_VALUE(2)
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#define TYPE_TAG_VECTOR SPECIAL_VALUE(3)
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#define TYPE_TAG_BYTESTR SPECIAL_VALUE(4)
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typedef struct pair
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{
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value_t car;
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value_t cdr;
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} pair_t;
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typedef struct object
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{
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value_t tag;
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union {
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value_t values[0];
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char bytes[0];
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} payload;
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} object_t;
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typedef struct vector
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{
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value_t tag;
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size_t size;
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value_t elements[0];
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} vector_t;
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typedef struct byte_string
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{
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value_t tag;
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size_t size;
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uint8_t bytes[0];
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} byte_string_t;
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typedef struct gc_root
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{
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value_t value;
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struct gc_root *prev;
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struct gc_root *next;
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} gc_root_t;
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static inline bool is_pair(value_t v)
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{
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return ((v & 0x3) == 0) && (v > MAX_SPECIAL);
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}
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static inline bool is_object(value_t v)
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{
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return ((v & 0x1) == 0) && (v > MAX_SPECIAL);
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}
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static inline bool is_fixnum(value_t v)
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{
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return (v & 1) != 0;
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}
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static inline value_t to_fixnum(intptr_t n)
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{
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return (value_t)(n << 1) | 1;
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}
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static inline intptr_t from_fixnum(value_t n)
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{
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return ((intptr_t)n) >> 1;
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}
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static inline value_t pair_value(pair_t *p)
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{
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return (value_t)p;
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}
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static inline value_t object_value(void *obj)
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{
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return (value_t)obj | 2;
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}
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object_t *get_object(value_t v);
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pair_t *get_pair(value_t pair);
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value_t get_cdr(value_t pair);
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void replace_car(value_t pair, value_t car);
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void replace_cdr(value_t pair, value_t cdr);
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value_t cons(value_t car, value_t cdr);
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void register_gc_root(gc_root_t *root, value_t v);
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void unregister_gc_root(gc_root_t *root);
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void *gc_alloc(size_t nbytes);
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void collect_garbage(size_t min_free);
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/***********************************************/
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/* Alignment must ensure each object has enough room to hold a pair (BH . new_addr) */
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#define GC_ALIGNMENT ((size_t)(sizeof(pair_t)))
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/* Pairs are a type of object, but the value representation is different */
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object_t *get_object(value_t v)
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@ -130,13 +26,11 @@ object_t *get_object(value_t v)
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pair_t *get_pair(value_t v)
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{
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if (is_pair(v))
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return (pair_t*)v;
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return (pair_t*)(v - 2);
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else
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abort();
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}
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static int cons_counter = 0;
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value_t cons(value_t car, value_t cdr)
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{
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gc_root_t car_root, cdr_root;
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@ -152,26 +46,23 @@ value_t cons(value_t car, value_t cdr)
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unregister_gc_root(&car_root);
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unregister_gc_root(&cdr_root);
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++cons_counter;
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return pair_value(p);
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}
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/* Equal to the max. active set size. */
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#define GC_RANGE_SIZE (256*1024*1024)
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static char *gc_ranges[2];
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static size_t gc_min_size;
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static size_t gc_max_size;
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static size_t gc_soft_limit;
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/* GC starts after this much space has been allocated. Increases by 5% each time. */
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#define GC_INIT_SIZE 1024
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static int gc_current_range;
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static size_t gc_free_space;
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static char *gc_free_ptr;
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/* Alignment must ensure each object has enough room to hold a pair (BH . new_addr) */
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#define GC_ALIGNMENT ((size_t)(sizeof(pair_t)))
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static pair_t gc_ranges[2][GC_RANGE_SIZE / sizeof(pair_t)];
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static char *gc_free_ptr = (char*)&gc_ranges[0][0];
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static size_t gc_free_space = GC_INIT_SIZE;
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static size_t gc_soft_limit = GC_INIT_SIZE;
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static int current_gc_range = 0;
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static gc_root_t gc_root_list = { NIL, &gc_root_list, &gc_root_list };
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static gc_root_t gc_root_list = {
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.value = NIL,
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.prev = &gc_root_list,
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.next = &gc_root_list
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};
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static inline size_t gc_align(size_t nbytes) __attribute__ ((const));
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static int gc_range_of(void *object) __attribute__ ((const));
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@ -194,6 +85,24 @@ static int gc_range_of(void *object)
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return -1;
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}
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void gc_init(size_t min_size, size_t max_size)
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{
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assert(min_size <= max_size);
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gc_ranges[0] = (char*)malloc(max_size);
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gc_ranges[1] = (char*)malloc(max_size);
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assert(gc_ranges[0] && gc_ranges[1]);
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gc_current_range = 0;
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gc_free_ptr = gc_ranges[gc_current_range];
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gc_min_size = min_size;
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gc_max_size = max_size;
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gc_soft_limit = gc_min_size;
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gc_free_space = gc_soft_limit;
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}
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void register_gc_root(gc_root_t *root, value_t v)
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{
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root->value = v;
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@ -216,13 +125,6 @@ void unregister_gc_root(gc_root_t *root)
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root->prev = root->next = root;
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}
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static void out_of_memory(void) __attribute__ ((noreturn));
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static void out_of_memory(void)
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{
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fprintf(stderr, "Out of memory!\n");
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abort();
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}
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void *gc_alloc(size_t nbytes)
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{
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nbytes = gc_align(nbytes);
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@ -244,7 +146,7 @@ static void transfer_object(value_t *value)
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object_t *obj = get_object(*value);
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value_t new_value;
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assert(gc_range_of(obj) != current_gc_range);
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assert(gc_range_of(obj) != gc_current_range);
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if (obj->tag == BROKEN_HEART)
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{
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@ -296,10 +198,10 @@ static void transfer_object(value_t *value)
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#ifndef NDEBUG
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if (is_pair(new_value))
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{
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if (gc_range_of(get_pair(new_value)) != current_gc_range)
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if (gc_range_of(get_pair(new_value)) != gc_current_range)
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{
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debug(("Invalid address after transfer: 0x%0.8X. Current GC: %d.\n",
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get_pair(new_value), current_gc_range));
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get_pair(new_value), gc_current_range));
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abort();
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}
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}
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@ -360,9 +262,12 @@ void collect_garbage(size_t min_free)
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else
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collecting = true;
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++gc_counter;
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gc_ticks -= (int)clock();
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/* Swap ranges; new "current" range is initially empty, old one is full */
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current_gc_range = 1 - current_gc_range;
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gc_free_ptr = (char*)&gc_ranges[current_gc_range][0];
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gc_current_range = 1 - gc_current_range;
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gc_free_ptr = (char*)&gc_ranges[gc_current_range][0];
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gc_free_space = gc_soft_limit;
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object_ptr = gc_free_ptr;
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@ -388,12 +293,12 @@ void collect_garbage(size_t min_free)
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size_t min_limit = bytes_used + min_free;
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size_t new_limit = (3 * min_limit) / 2;
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if (new_limit > GC_RANGE_SIZE)
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new_limit = GC_RANGE_SIZE;
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else if (new_limit < GC_INIT_SIZE)
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new_limit = GC_INIT_SIZE;
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if (new_limit > gc_max_size)
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new_limit = gc_max_size;
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else if (new_limit < gc_min_size)
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new_limit = gc_min_size;
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gc_free_space += (new_limit - gc_soft_limit);
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gc_free_space = (gc_free_space + new_limit) - gc_soft_limit;
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gc_soft_limit = new_limit;
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}
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@ -404,57 +309,8 @@ void collect_garbage(size_t min_free)
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/* Done collecting. */
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collecting = false;
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}
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int main(int argc, char **argv)
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{
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struct timeval start_time;
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gc_root_t list_root;
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int count = 0;
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gettimeofday(&start_time, NULL);
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srand((unsigned int)start_time.tv_usec);
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register_gc_root(&list_root, NIL);
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while (1)
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{
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int r = rand() & 0xffff;
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if (r == 0)
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list_root.value = to_fixnum(rand());
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else if (r & 1)
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list_root.value = cons(to_fixnum(rand()), list_root.value);
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else if (r & 2)
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list_root.value = cons(list_root.value, to_fixnum(rand()));
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else if (r & 4)
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{
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list_root.value = cons(list_root.value, cons(to_fixnum(-1), NIL));
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get_pair(get_pair(list_root.value)->cdr)->cdr = list_root.value;
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}
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if (cons_counter >= 1000000)
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{
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struct timeval end_time;
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double seconds;
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gettimeofday(&end_time, NULL);
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seconds = (end_time.tv_sec - start_time.tv_sec)
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+ 0.000001 * (end_time.tv_usec - start_time.tv_usec);
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printf("%d conses took %.6f seconds.\n", cons_counter, seconds);
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gettimeofday(&start_time, NULL);
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cons_counter = 0;
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if (++count == 50)
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break;
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}
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}
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unregister_gc_root(&list_root);
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return 0;
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gc_ticks += (int)clock();
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}
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/* vim:set sw=2 expandtab: */
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@ -0,0 +1,126 @@
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#ifndef GC_H_6b8a27c99f2eb5eb5437e045fa4af1c3
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#define GC_H_6b8a27c99f2eb5eb5437e045fa4af1c3
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#include <assert.h>
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#include <inttypes.h>
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#include <stdbool.h>
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#include <stdio.h>
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#ifndef NDEBUG
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# define debug(printf_args) ((void)printf printf_args)
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#else
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# define debug(printf_args) ((void)0)
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#endif
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typedef uintptr_t value_t;
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/* NIL: 00000000 00000000 00000000 00000000 */
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/* Object: aaaaaaaa aaaaaaaa aaaaaaaa aaaaaa00 (where aa... >= 1024) */
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/* Pair: aaaaaaaa aaaaaaaa aaaaaaaa aaaaaa10 */
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/* Fixnum: snnnnnnn nnnnnnnn nnnnnnnn nnnnnnn1 */
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#define NIL ((value_t)0)
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/* Special values (0 <= n < 1024) */
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/* These correspond to objects within the first page of memory */
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#define SPECIAL_VALUE(n) ((value_t)(4*n+2))
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#define MAX_SPECIAL SPECIAL_VALUE(1023)
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#define BROKEN_HEART SPECIAL_VALUE(0)
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#define TYPE_TAG_BOX SPECIAL_VALUE(1)
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#define TYPE_TAG_VECTOR SPECIAL_VALUE(2)
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#define TYPE_TAG_BYTESTR SPECIAL_VALUE(3)
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typedef struct pair
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{
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value_t car;
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value_t cdr;
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} pair_t;
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typedef struct object
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{
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value_t tag;
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union {
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value_t values[0];
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char bytes[0];
|
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} payload;
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} object_t;
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typedef struct vector
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{
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value_t tag;
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size_t size;
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value_t elements[0];
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} vector_t;
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|
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typedef struct byte_string
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{
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value_t tag;
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size_t size;
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uint8_t bytes[0];
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} byte_string_t;
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typedef struct gc_root
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{
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value_t value;
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struct gc_root *prev;
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struct gc_root *next;
|
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} gc_root_t;
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static inline bool is_pair(value_t v)
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{
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return ((v & 0x3) == 2);
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}
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|
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static inline bool is_object(value_t v)
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{
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/* Neither pairs nor objects can exist below (void*)4096. */
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return ((v & 0x1) == 0) && (v > MAX_SPECIAL);
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}
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static inline bool is_fixnum(value_t v)
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{
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return (v & 1) != 0;
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}
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static inline value_t to_fixnum(intptr_t n)
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{
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return (value_t)(n << 1) | 1;
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}
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static inline intptr_t from_fixnum(value_t n)
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{
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return ((intptr_t)n) >> 1;
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}
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|
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static inline value_t pair_value(pair_t *p)
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{
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assert((uintptr_t)p >= 4096);
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assert(((uintptr_t)p & 3) == 0);
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return (value_t)p + 2;
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}
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static inline value_t object_value(void *obj)
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{
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assert((uintptr_t)obj >= 4096);
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assert(((uintptr_t)obj & 3) == 0);
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return (value_t)obj;
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}
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object_t *get_object(value_t v);
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pair_t *get_pair(value_t pair);
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value_t get_cdr(value_t pair);
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value_t cons(value_t car, value_t cdr);
|
||||
|
||||
void gc_init(size_t min_size, size_t max_size);
|
||||
void register_gc_root(gc_root_t *root, value_t v);
|
||||
void unregister_gc_root(gc_root_t *root);
|
||||
void *gc_alloc(size_t nbytes);
|
||||
void collect_garbage(size_t min_free);
|
||||
|
||||
/* To be provided by the main application */
|
||||
void out_of_memory(void) __attribute__ ((noreturn));
|
||||
|
||||
#endif
|
||||
|
||||
/* vim:set sw=2 expandtab: */
|
||||
|
|
@ -0,0 +1,69 @@
|
|||
#include <sys/time.h>
|
||||
|
||||
#include <inttypes.h>
|
||||
#include <stdbool.h>
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include <time.h>
|
||||
|
||||
#include "gc.h"
|
||||
|
||||
int gc_counter;
|
||||
int gc_ticks;
|
||||
|
||||
void out_of_memory(void)
|
||||
{
|
||||
fprintf(stderr, "Out of memory!\n");
|
||||
abort();
|
||||
}
|
||||
|
||||
int main(int argc, char **argv)
|
||||
{
|
||||
gc_root_t list_root;
|
||||
int count = 0;
|
||||
|
||||
gc_init(1024, 256*1024*1024);
|
||||
|
||||
gc_counter = 0;
|
||||
gc_ticks = 0;
|
||||
|
||||
srand((unsigned int)time(NULL));
|
||||
|
||||
register_gc_root(&list_root, NIL);
|
||||
|
||||
while (1)
|
||||
{
|
||||
int r = rand() & 0xffff;
|
||||
|
||||
if (r == 0)
|
||||
list_root.value = to_fixnum(rand());
|
||||
else if (r & 1)
|
||||
list_root.value = cons(to_fixnum(rand()), list_root.value);
|
||||
else if (r & 2)
|
||||
list_root.value = cons(list_root.value, to_fixnum(rand()));
|
||||
else if (r & 4)
|
||||
{
|
||||
list_root.value = cons(list_root.value, cons(to_fixnum(-1), NIL));
|
||||
get_pair(get_pair(list_root.value)->cdr)->cdr = list_root.value;
|
||||
}
|
||||
|
||||
if (gc_counter >= 1000)
|
||||
{
|
||||
fprintf(stderr, "%d collections in %0.3f seconds = %0.3f usec / GC\n",
|
||||
gc_counter,
|
||||
gc_ticks / (double)CLOCKS_PER_SEC,
|
||||
(1000000 * (gc_ticks / (double)CLOCKS_PER_SEC)) / gc_counter);
|
||||
gc_counter = gc_ticks = 0;
|
||||
|
||||
if (++count == 10)
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
unregister_gc_root(&list_root);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* vim:set sw=2 expandtab: */
|
||||
Loading…
Reference in New Issue