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Add gc_object_is_old_generation

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Will be useful for write barriers.
This commit is contained in:
Andy Wingo 2024-10-01 15:44:55 +02:00
parent 42bf36d7cc
commit 1493bf6398
12 changed files with 119 additions and 4 deletions
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32
api/gc-api.h
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@ -179,6 +179,33 @@ static inline void* gc_allocate(struct gc_mutator *mut, size_t size) {
// FIXME: remove :P
GC_API_ void* gc_allocate_pointerless(struct gc_mutator *mut, size_t bytes);
GC_API_ int gc_object_is_old_generation_slow(struct gc_mutator *mut,
struct gc_ref obj) GC_NEVER_INLINE;
static inline int gc_object_is_old_generation(struct gc_mutator *mut,
struct gc_ref obj,
size_t obj_size) GC_ALWAYS_INLINE;
static inline int gc_object_is_old_generation(struct gc_mutator *mut,
struct gc_ref obj,
size_t obj_size) {
switch (gc_old_generation_check_kind(obj_size)) {
case GC_OLD_GENERATION_CHECK_ALLOC_TABLE: {
size_t alignment = gc_allocator_alloc_table_alignment();
GC_ASSERT(alignment);
uintptr_t addr = gc_ref_value(obj);
uintptr_t base = addr & ~(alignment - 1);
size_t granule_size = gc_allocator_small_granule_size();
uintptr_t granule = (addr & (alignment - 1)) / granule_size;
uint8_t *byte = (uint8_t*)(base + granule);
return (*byte) & gc_old_generation_check_alloc_table_bit_pattern();
}
case GC_OLD_GENERATION_CHECK_SLOW:
return gc_object_is_old_generation_slow(mut, obj);
default:
GC_CRASH();
}
}
GC_API_ void gc_write_barrier_slow(struct gc_mutator *mut, struct gc_ref obj,
size_t obj_size, struct gc_edge edge,
struct gc_ref new_val) GC_NEVER_INLINE;
@ -202,11 +229,14 @@ static inline void gc_write_barrier(struct gc_mutator *mut, struct gc_ref obj,
return;
}
case GC_WRITE_BARRIER_FIELD: {
if (!gc_object_is_old_generation(mut, obj, obj_size))
return;
size_t field_table_alignment = gc_write_barrier_field_table_alignment();
size_t fields_per_byte = gc_write_barrier_field_fields_per_byte();
uint8_t first_bit_pattern = gc_write_barrier_field_first_bit_pattern();
uintptr_t addr = (uintptr_t) gc_edge_loc(edge);
uintptr_t addr = gc_ref_value(obj);
uintptr_t base = addr & ~(field_table_alignment - 1);
uintptr_t field = (addr & (field_table_alignment - 1)) / sizeof(uintptr_t);
uintptr_t log_byte = field / fields_per_byte;