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Decided to put class instances on heap
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@Noisyfox
Noisyfox committed Jan 10, 2019
1 parent 3246ccf commit 9a1e3b2
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Showing 2 changed files with 69 additions and 49 deletions.
10 changes: 4 additions & 6 deletions native/runtime/include/vm_base.h
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Original file line number Diff line number Diff line change
Expand Up @@ -75,22 +75,20 @@ typedef struct {
FieldDesc *fields;
} FieldTable;

/**
* This class will not be allocated on heap.
* Instead it will be stored on native memory.
*/
struct _JavaClass {
OPA_ptr_t ref; // Class list ptr
OPA_ptr_t ref;
OPA_ptr_t clazz; // Always NULL for class instance
void *monitor;

const char *className;

JAVA_OBJECT classLoader;

JAVA_CLASS parentClass;
int interfaceCount;
JAVA_CLASS *parentInterfaces;

FieldTable* fieldTable; // Fields of parent classes are not included here.
FieldTable *fieldTable; // Fields of parent classes are not included here.
};

// Object prototype
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108 changes: 65 additions & 43 deletions native/runtime/memory/vm_gc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -147,6 +147,22 @@ static inline uint8_t *ptr_old_gen_bytemap_slot(void *ptr) {
return &oldGen->byteMap[slotNum];
}

static inline JAVA_BOOLEAN ptr_olg_gen_is_clean(void *ptr, JAVA_BOOLEAN young_only) {
if (young_only) {
uint8_t *bytemap_slot = ptr_old_gen_bytemap_slot(ptr);
if (bytemap_slot != NULL) {
// Check if it's marked as having ref to young gen
uint8_t mark = *bytemap_slot;
if ((mark & CARDTABLE_DIRTY) != CARDTABLE_DIRTY) {
// Doesn't have reference to young gen
return JAVA_TRUE;
}
}
}

return JAVA_FALSE;
}

int heap_init(VM_PARAM_CURRENT_CONTEXT, HeapConfig *config) {
mem_init();

Expand Down Expand Up @@ -462,23 +478,24 @@ static GCType gc_trigger(VM_PARAM_CURRENT_CONTEXT, GCType type) {

#define obj_marked(obj, flag) obj_test_flags_and((obj), (flag))

static JAVA_VOID mark_object(JAVA_OBJECT obj, uintptr_t gc_flag, JAVA_BOOLEAN young_only) {
if (obj == JAVA_NULL) {
return;
}
static JAVA_VOID mark_object(JAVA_OBJECT obj, uintptr_t gc_flag, JAVA_BOOLEAN young_only);

// Ignore any object that is a Class
JAVA_CLASS currentClass = obj_get_class(obj);
if (currentClass == (JAVA_CLASS) JAVA_NULL) {
return;
static JAVA_VOID mark_class(JAVA_CLASS clazz, uintptr_t gc_flag, JAVA_BOOLEAN young_only);

static inline JAVA_VOID mark_dirty_object(JAVA_OBJECT obj, uintptr_t gc_flag, JAVA_BOOLEAN young_only) {
if (ptr_olg_gen_is_clean(obj, young_only) != JAVA_TRUE) {
mark_object(obj, gc_flag, young_only);
}
}

// Already marked
if (obj_marked(obj, gc_flag) == JAVA_TRUE) {
return;
static inline JAVA_VOID mark_dirty_class(JAVA_CLASS clazz, uintptr_t gc_flag, JAVA_BOOLEAN young_only) {
if (ptr_olg_gen_is_clean(clazz, young_only) != JAVA_TRUE) {
mark_class(clazz, gc_flag, young_only);
}
}

// Mark current obj
static inline JAVA_VOID do_mark_obj(JAVA_OBJECT obj, uintptr_t gc_flag) {
// Mark obj
obj_reset_flags_masked(obj, OBJECT_FLAG_GC_MARK_MASK, gc_flag);

// Increase living time if it's in young gen
Expand All @@ -492,6 +509,30 @@ static JAVA_VOID mark_object(JAVA_OBJECT obj, uintptr_t gc_flag, JAVA_BOOLEAN yo
uintptr_t age_flags = age << OBJECT_FLAG_AGE_SHIFT;
obj_reset_flags_masked(obj, OBJECT_FLAG_GC_MARK_MASK, age_flags);
}
}

static JAVA_VOID mark_object(JAVA_OBJECT obj, uintptr_t gc_flag, JAVA_BOOLEAN young_only) {
if (obj == JAVA_NULL) {
return;
}

// Class instance need to be handled separately
JAVA_CLASS currentClass = obj_get_class(obj);
if (currentClass == (JAVA_CLASS) JAVA_NULL) {
mark_class((JAVA_CLASS) obj, gc_flag, young_only);
return;
}

// Already marked
if (obj_marked(obj, gc_flag) == JAVA_TRUE) {
return;
}

// Mark current obj
do_mark_obj(obj, gc_flag);

// Mark class instance first
mark_dirty_class(currentClass, gc_flag, young_only);

// Then walk pass all instance fields and mark reference fields
while (currentClass != (JAVA_CLASS) JAVA_NULL) {
Expand All @@ -510,19 +551,7 @@ static JAVA_VOID mark_object(JAVA_OBJECT obj, uintptr_t gc_flag, JAVA_BOOLEAN yo
}

JAVA_OBJECT referencedObj = *((JAVA_OBJECT *) (ptr_inc(obj, desc->offset)));
if (young_only) {
uint8_t *bytemap_slot = ptr_old_gen_bytemap_slot(referencedObj);
if (bytemap_slot != NULL) {
// Check if it's marked as having ref to young gen
uint8_t mark = *bytemap_slot;
if ((mark & CARDTABLE_DIRTY) != CARDTABLE_DIRTY) {
// Doesn't have reference to young gen, skip
continue;
}
}
}

mark_object(referencedObj, gc_flag, young_only);
mark_dirty_object(referencedObj, gc_flag, young_only);
}

// Then mark parent class fields
Expand All @@ -541,7 +570,10 @@ static JAVA_VOID mark_class(JAVA_CLASS clazz, uintptr_t gc_flag, JAVA_BOOLEAN yo
}

// Mark current class
obj_reset_flags_masked((JAVA_OBJECT) clazz, OBJECT_FLAG_GC_MARK_MASK, gc_flag);
do_mark_obj((JAVA_OBJECT) clazz, gc_flag);

// Mark classloader first
mark_dirty_object(clazz->classLoader, gc_flag, young_only);

// Then walk pass all static fields and mark reference fields
FieldTable *fieldTable = clazz->fieldTable;
Expand All @@ -558,34 +590,24 @@ static JAVA_VOID mark_class(JAVA_CLASS clazz, uintptr_t gc_flag, JAVA_BOOLEAN yo
}

JAVA_OBJECT referencedObj = *((JAVA_OBJECT *) (ptr_inc(clazz, desc->offset)));
if (young_only) {
uint8_t *bytemap_slot = ptr_old_gen_bytemap_slot(referencedObj);
if (bytemap_slot != NULL) {
// Check if it's marked as having ref to young gen
uint8_t mark = *bytemap_slot;
if ((mark & CARDTABLE_DIRTY) != CARDTABLE_DIRTY) {
// Doesn't have reference to young gen, skip
continue;
}
}
}

mark_object(referencedObj, gc_flag, young_only);
mark_dirty_object(referencedObj, gc_flag, young_only);
}

// We don't need to mark parent classes here since we will mark all classes
// Mark parent classes
mark_dirty_class(clazz->parentClass, gc_flag, young_only);
for (int i = 0; i < clazz->interfaceCount; i++) {
mark_dirty_class(clazz->parentInterfaces[i], gc_flag, young_only);
}
}

static JAVA_VOID gc_minor(uintptr_t gc_flag) {
VMThreadContext *thread = NULL;

// TODO: go through all Class instances first since they are out of heap

while ((thread = thread_managed_next(thread)) != NULL) {
// Mark the thread object first
mark_object(thread->currentThread, gc_flag, JAVA_TRUE);

// Then mark the thread stack
// TODO: Then mark the thread stack

}
}
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