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bring back liftdestructors.nim to its simpler logic

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Araq
2026-06-20 10:22:18 +02:00
parent 8e5ba13fe3
commit da2925bae8
1 changed files with 6 additions and 39 deletions
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45
compiler/liftdestructors.nim
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@@ -761,28 +761,6 @@ proc cyclicType*(g: ModuleGraph, t: PType): bool =
of tyProc: result = t.callConv == ccClosure
else: result = false
proc recHasNilFieldType(n: PNode): bool =
case n.kind
of nkSym: result = n.sym == nil or n.sym.typ == nil
of nkRecList, nkRecCase:
for ch in n:
if recHasNilFieldType(ch): return true
result = false
else: result = false
proc isTypeErasedEnvRef(config: ConfigRef; elemType: PType): bool =
## IC: a foreign closure-env object can load (cross-module) with nil-typed
## derived fields when its hook key diverges across the NIF boundary. Per the
## closure type-erasure principle, destroying such a `ref` must go through RTTI
## (`nimDestroyAndDispose` / `nimDecRefIsLastCyclicDyn`), NEVER a statically
## lifted concrete env destructor — the producer module emits that destructor
## and registers it in the env object's type info. Detect the incomplete load
## so `atomicRefOp` takes the dynamic-dispatch path and never walks the nil
## field (which would SIGSEGV).
if not config.icLoweredBodies: return false
let obj = elemType.skipTypes({tyGenericInst, tyAlias, tySink, tyOwned})
result = obj.kind == tyObject and obj.n != nil and recHasNilFieldType(obj.n)
proc atomicRefOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
#[ bug #15753 is really subtle. Usually the classical write barrier for reference
counting looks like this::
@@ -815,17 +793,13 @@ proc atomicRefOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
]#
var actions = newNodeI(nkStmtList, c.info)
let elemType = t.elementType
# (b) type-erasure: a foreign closure env that loaded incomplete cross-module
# must be destroyed via RTTI, not by lifting its concrete (nil-fielded) object.
let erased = isTypeErasedEnvRef(c.g.config, elemType)
if not erased:
createTypeBoundOps(c.g, c.c, elemType, c.info, c.idgen)
createTypeBoundOps(c.g, c.c, elemType, c.info, c.idgen)
# YRC uses dedicated runtime procs for the entire write barrier:
if c.g.config.selectedGC == gcYrc:
let desc =
if isFinal(elemType) and not erased:
if isFinal(elemType):
let ti = genBuiltin(c, mGetTypeInfoV2, "getTypeInfoV2", newNodeIT(nkType, x.info, elemType))
ti.typ = getSysType(c.g, c.info, tyPointer)
ti
@@ -840,18 +814,14 @@ proc atomicRefOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
return
else: discard # fall through for destructor, trace, wasMoved
# `erased` must short-circuit BEFORE canFormAcycle/isPureObject/isFinal, which
# walk the (nil-fielded) type graph. Assume cyclic + dynamic — the dyn runtime
# calls work for any ref via its type info.
let isCyclic = erased or
(c.g.config.selectedGC in {gcOrc, gcYrc} and types.canFormAcycle(c.g, elemType))
let isCyclic = c.g.config.selectedGC in {gcOrc, gcYrc} and types.canFormAcycle(c.g, elemType)
let isInheritableAcyclicRef = (not erased) and c.g.config.selectedGC in {gcOrc, gcYrc} and
let isInheritableAcyclicRef = c.g.config.selectedGC in {gcOrc, gcYrc} and
(not isPureObject(elemType)) and
tfAcyclic in skipTypes(elemType, abstractInst+{tyOwned}-{tyTypeDesc}).flags
# dynamic Acyclic refs need to use dyn decRef
let useStatic = (not erased) and isFinal(elemType)
let useStatic = isFinal(elemType)
let tmp =
if isCyclic and c.kind in {attachedAsgn, attachedSink, attachedDup}:
@@ -865,10 +835,7 @@ proc atomicRefOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
alignOf.typ = getSysType(c.g, c.info, tyInt)
actions.add callCodegenProc(c.g, "nimRawDispose", c.info, tmp, alignOf)
else:
# `nimDestroyAndDispose` resolves the real destructor via the object's RTTI,
# so the env destructor the producer emitted runs — no static lift needed.
if not erased:
addDestructorCall(c, elemType, newNodeI(nkStmtList, c.info), genDeref(tmp, nkDerefExpr))
addDestructorCall(c, elemType, newNodeI(nkStmtList, c.info), genDeref(tmp, nkDerefExpr))
actions.add callCodegenProc(c.g, "nimDestroyAndDispose", c.info, tmp)
var cond: PNode