gc: implement slot-based bitmap indexing with division magic

Replace the BASE_SLOT_SIZE-granularity bitmap scheme with slot-based
indexing where each bit represents one slot regardless of size.

Key changes:
- Add slot_div_magic field to heap_page for fast division
- Use Go-inspired formula: slot_index = (offset * div_magic) >> 32
- Update all bitmap iteration to use one-bit-per-slot scheme
- Remove slot_bits_mask from rb_heap_t (no longer needed)

This enables arbitrary slot sizes (not just power-of-two multiples of
BASE_SLOT_SIZE) by decoupling bitmap indexing from slot size.

Functions updated:
- gc_sweep_plane/gc_sweep_page
- rgengc_rememberset_mark/rgengc_rememberset_mark_plane
- gc_marks_wb_unprotected_objects/gc_marks_wb_unprotected_objects_plane
- gc_compact_plane/gc_compact_page
- invalidate_moved_plane/invalidate_moved_page
- RVALUE_AGE_GET/RVALUE_AGE_SET_BITMAP

Inspired by Go runtime's mbitmap.go divideByElemSize().

0 files changed, 0 insertions, 0 deletions