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Rework write barrier fast/slow paths

This commit is contained in:
Andy Wingo 2024-10-02 21:36:33 +02:00
parent 1ecb45a437
commit 095515eaed

View file

@ -210,15 +210,15 @@ 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;
static inline void gc_write_barrier(struct gc_mutator *mut, struct gc_ref obj,
size_t obj_size, struct gc_edge edge,
struct gc_ref new_val) GC_ALWAYS_INLINE;
static inline void gc_write_barrier(struct gc_mutator *mut, struct gc_ref obj,
size_t obj_size, struct gc_edge edge,
struct gc_ref new_val) {
static inline int gc_write_barrier_fast(struct gc_mutator *mut, struct gc_ref obj,
size_t obj_size, struct gc_edge edge,
struct gc_ref new_val) GC_ALWAYS_INLINE;
static inline int gc_write_barrier_fast(struct gc_mutator *mut, struct gc_ref obj,
size_t obj_size, struct gc_edge edge,
struct gc_ref new_val) {
switch (gc_write_barrier_kind(obj_size)) {
case GC_WRITE_BARRIER_NONE:
return;
return 0;
case GC_WRITE_BARRIER_CARD: {
size_t card_table_alignment = gc_write_barrier_card_table_alignment();
size_t card_size = gc_write_barrier_card_size();
@ -226,11 +226,11 @@ static inline void gc_write_barrier(struct gc_mutator *mut, struct gc_ref obj,
uintptr_t base = addr & ~(card_table_alignment - 1);
uintptr_t card = (addr & (card_table_alignment - 1)) / card_size;
atomic_store_explicit((uint8_t*)(base + card), 1, memory_order_relaxed);
return;
return 0;
}
case GC_WRITE_BARRIER_FIELD: {
if (!gc_object_is_old_generation(mut, obj, obj_size))
return;
return 0;
size_t field_table_alignment = gc_write_barrier_field_table_alignment();
size_t fields_per_byte = gc_write_barrier_field_fields_per_byte();
@ -243,18 +243,25 @@ static inline void gc_write_barrier(struct gc_mutator *mut, struct gc_ref obj,
uint8_t log_bit = first_bit_pattern << (field % fields_per_byte);
uint8_t *byte_loc = (uint8_t*)(base + log_byte);
uint8_t byte = atomic_load_explicit(byte_loc, memory_order_relaxed);
if (!(byte & log_bit))
gc_write_barrier_slow(mut, obj, obj_size, edge, new_val);
return;
return byte & log_bit;
}
case GC_WRITE_BARRIER_SLOW:
gc_write_barrier_slow(mut, obj, obj_size, edge, new_val);
return;
return 1;
default:
GC_CRASH();
}
}
static inline void gc_write_barrier(struct gc_mutator *mut, struct gc_ref obj,
size_t obj_size, struct gc_edge edge,
struct gc_ref new_val) GC_ALWAYS_INLINE;
static inline void gc_write_barrier(struct gc_mutator *mut, struct gc_ref obj,
size_t obj_size, struct gc_edge edge,
struct gc_ref new_val) {
if (GC_UNLIKELY(gc_write_barrier_fast(mut, obj, obj_size, edge, new_val)))
gc_write_barrier_slow(mut, obj, obj_size, edge, new_val);
}
GC_API_ void gc_pin_object(struct gc_mutator *mut, struct gc_ref obj);
GC_API_ void gc_safepoint_slow(struct gc_mutator *mut) GC_NEVER_INLINE;