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#include <stdlib.h>
#include "compiler.h"
#include "memory.h"
#include "vm.h"
#ifdef DEBUG_LOG_GC
#include "debug.h"
#include <stdio.h>
#endif
void *reallocate(void *pointer, size_t oldSize, size_t newSize) {
if (newSize > oldSize) {
#ifdef DEBUG_STRESS_GC
collectGarbage();
#endif
}
if (newSize == 0) {
free(pointer);
return NULL;
}
void *result = realloc(pointer, newSize);
if (result == NULL)
exit(1);
return result;
}
void markObject(Obj *object) {
if (object == NULL)
return;
if (object->isMarked)
return;
#ifdef DEBUG_LOG_GC
printf("%p mark ", (void *)object);
printValue(OBJ_VAL(object));
printf("\n");
#endif
object->isMarked = true;
if (vm.grayCapacity < vm.grayCount + 1) {
vm.grayCapacity = GROW_CAPACITY(vm.grayCapacity);
vm.grayStack =
(Obj **)realloc(vm.grayStack, sizeof(Obj *) * vm.grayCapacity);
if (vm.grayStack == NULL)
exit(1);
}
vm.grayStack[vm.grayCount++] = object;
}
void markValue(Value value) {
if (IS_OBJ(value))
markObject(AS_OBJ(value));
}
static void markArray(ValueArray *array) {
for (int i = 0; i < array->count; i++) {
markValue(array->values[i]);
}
}
static void blackenObject(Obj *object) {
#ifdef DEBUG_LOG_GC
printf("%p blacken ", (void *)object);
printValue(OBJ_VAL(object));
printf("\n");
#endif
switch (object->type) {
case OBJ_CLOSURE: {
ObjClosure *closure = (ObjClosure *)object;
markObject((Obj *)closure->function);
for (int i = 0; i < closure->upvalueCount; i++) {
markObject((Obj *)closure->upvalues[i]);
}
break;
}
case OBJ_FUNCTION: {
ObjFunction *function = (ObjFunction *)object;
markObject((Obj *)function->name);
markArray(&function->chunk.constants);
break;
}
case OBJ_UPVALUE:
markValue(((ObjUpvalue *)object)->closed);
break;
case OBJ_NATIVE:
case OBJ_STRING:
break;
}
}
static void freeObject(Obj *object) {
#ifdef DEBUG_LOG_GC
printf("%p free type %d\n", (void *)object, object->type);
#endif // DEBUG_LOG_GC
switch (object->type) {
case OBJ_CLOSURE: {
ObjClosure *closure = (ObjClosure *)object;
FREE_ARRAY(ObjUpvalue *, closure->upvalues, closure->upvalueCount);
FREE(ObjClosure, object);
break;
}
case OBJ_FUNCTION: {
ObjFunction *function = (ObjFunction *)object;
freeChunk(&function->chunk);
FREE(ObjFunction, object);
break;
}
case OBJ_NATIVE:
FREE(ObjNative, object);
break;
case OBJ_STRING: {
ObjString *string = (ObjString *)object;
FREE_ARRAY(char, string->chars, string->length + 1);
FREE(ObjString, object);
break;
}
case OBJ_UPVALUE:
FREE(ObjUpvalue, object);
break;
}
}
static void markRoots() {
for (Value *slot = vm.stack; slot < vm.stackTop; slot++) {
markValue(*slot);
}
for (int i = 0; i < vm.frameCount; i++) {
markObject((Obj *)vm.frames[i].closure);
}
for (ObjUpvalue *upvalue = vm.openUpvalues; upvalue != NULL;
upvalue = upvalue->next) {
markObject((Obj *)upvalue);
}
markTable(&vm.globals);
markCompilerRoots();
}
static void traceReferences() {
while (vm.grayCount > 0) {
Obj *object = vm.grayStack[--vm.grayCount];
blackenObject(object);
}
}
static void sweep() {
Obj *previous = NULL;
Obj *object = vm.objects;
while (object != NULL) {
if (object->isMarked) {
object->isMarked = false;
previous = object;
object = object->next;
} else {
Obj *unreached = object;
object = object->next;
if (previous != NULL) {
previous->next = object;
} else {
vm.objects = object;
}
freeObject(unreached);
}
}
}
void collectGarbage() {
#ifdef DEBUG_LOG_GC
printf("-- gc begin\n");
#endif
markRoots();
traceReferences();
tableRemoveWhite(&vm.strings);
sweep();
#ifdef DEBUG_LOG_GC
printf("-- gd end\n");
#endif
}
void freeObjects() {
Obj *object = vm.objects;
while (object != NULL) {
Obj *next = object->next;
freeObject(object);
object = next;
}
free(vm.grayStack);
}
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