Class OwnershipLowering

java.lang.Object

org.ek9lang.compiler.phase9.OwnershipLowering

public final class OwnershipLowering
extends Object

THE ownership lowering (EK9_IR_OWNERSHIP_MODEL.md §11.1): rewrites every ownership-form instruction into today's opcodes, so both back ends keep consuming exactly what they consume now. Today's instructions pass through untouched (the mixed form, D-O9). Runs as the last step of IR_OPTIMISATION, after which no ownership opcode exists.

The lowering

ownership form	today's form
OWN v	RETAIN v
DROP v	RELEASE v
DROP_AT_EXIT v, s	SCOPE_REGISTER v, s
SLOT_DECLARE x, T, s [typed]	REFERENCE x, T (TYPED_REFERENCE when typed), and SCOPE_REGISTER x, s straight after the slot's first [init] assignment, wherever in the operation that is (a declaration can be hoisted out of the list that initialises it) - or straight after the declaration when nothing initialises it; nothing for a CALLER slot
SLOT_ASSIGN x, v [consume]	RELEASE x; STORE x, v (no RELEASE under [init])
SLOT_ASSIGN x, v [copy]	the same, then RETAIN x
FIELD_ASSIGN o.f, v [consume]	RELEASE_FIELD; STORE_FIELD (no RELEASE_FIELD under [init])
FIELD_ASSIGN o.f, v [copy]	the same, then RETAIN v
STATIC_FIELD_ASSIGN f, v [consume|copy, init]	STORE_STATIC_FIELD (then RETAIN v when [copy])
r = STATIC_FIELD_TAKE f	r = LOAD_STATIC_FIELD f

The lowering checks its output: every construct it lowers must be ARC-balanced in the lowered form (RetainReleaseBalanceVerifier, model rule V-L), or compilation stops - a wrong lowering is a compiler defect, never a silent leak. The ownership form it started from was IR_ANALYSIS's (OwnershipVerifier).

Constructor Summary

Constructors

Constructor	Description
OwnershipLowering()

Method Summary

Modifier and Type	Method	Description
void	lower(IRConstruct construct)	Lower every operation of a construct, then verify the lowered construct (V-L).
(package private) static List<IRInstr>	lowerList(List<IRInstr> instructions)	Lower an instruction list and every list nested in it, as one operation body.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

OwnershipLowering

public OwnershipLowering()

Method Details

lower

public void lower(IRConstruct construct)

Lower every operation of a construct, then verify the lowered construct (V-L).

lowerList

static List<IRInstr> lowerList(List<IRInstr> instructions)

Lower an instruction list and every list nested in it, as one operation body.