KOS_OP_ITEM_FAST_STORE_FAST

• Style: EXTRA (FASTVAR, FASTVAR, NOARG, NOARG).

• Stack: [..., obj] → [...]. Set obj[key] = value with the object on the stack, the key read from a fast slot and the value read from a fast slot.

• Cache: one KOS_CACHE_ITEM slot; the site elects a body for the container kind it first sees through the shared helper in eval/eval_item.c (see the items section of the VM reference).

• Compiler form: The lowering of ITEM_VAR_STORE_VAR: every named operand has a fast slot.

• Implementation: koskari/lib/opcode/ITEM_FAST_STORE_FAST.c