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destructors: do not produce strong backrefs in closure environments so that refcounting works

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This commit is contained in:
Araq
2019-01-30 18:17:40 +01:00
parent 0c2c2dca2a
commit 0a628f36f0
1 changed files with 17 additions and 4 deletions
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21
compiler/lambdalifting.nim
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@@ -320,17 +320,30 @@ proc getEnvTypeForOwner(c: var DetectionPass; owner: PSym;
rawAddSon(result, obj)
c.ownerToType[owner.id] = result
proc getEnvTypeForOwnerUp(c: var DetectionPass; owner: PSym;
info: TLineInfo): PType =
var r = c.getEnvTypeForOwner(owner, info)
result = newType(tyPtr, owner)
rawAddSon(result, r.base)
proc createUpField(c: var DetectionPass; dest, dep: PSym; info: TLineInfo) =
let refObj = c.getEnvTypeForOwner(dest, info) # getHiddenParam(dest).typ
let obj = refObj.lastSon
let fieldType = c.getEnvTypeForOwner(dep, info) #getHiddenParam(dep).typ
# The assumption here is that gcDestructors means we cannot deal
# with cycles properly, so it's better to produce a weak ref (=ptr) here.
# This seems to be generally correct but since it's a bit risky it's only
# enabled for gcDestructors.
let fieldType = if c.graph.config.selectedGc == gcDestructors:
c.getEnvTypeForOwnerUp(dep, info) #getHiddenParam(dep).typ
else:
c.getEnvTypeForOwner(dest, info)
if refObj == fieldType:
localError(c.graph.config, dep.info, "internal error: invalid up reference computed")
let upIdent = getIdent(c.graph.cache, upName)
let upField = lookupInRecord(obj.n, upIdent)
if upField != nil:
if upField.typ != fieldType:
if upField.typ.base != fieldType.base:
localError(c.graph.config, dep.info, "internal error: up references do not agree")
else:
let result = newSym(skField, upIdent, obj.owner, obj.owner.info)
@@ -555,7 +568,7 @@ proc rawClosureCreation(owner: PSym;
let upField = lookupInRecord(env.typ.lastSon.n, getIdent(d.graph.cache, upName))
if upField != nil:
let up = getUpViaParam(d.graph, owner)
if up != nil and upField.typ == up.typ:
if up != nil and upField.typ.base == up.typ.base:
result.add(newAsgnStmt(rawIndirectAccess(env, upField, env.info),
up, env.info))
#elif oldenv != nil and oldenv.typ == upField.typ:
@@ -586,7 +599,7 @@ proc closureCreationForIter(iter: PNode;
let upField = lookupInRecord(v.typ.lastSon.n, getIdent(d.graph.cache, upName))
if upField != nil:
let u = setupEnvVar(owner, d, c)
if u.typ == upField.typ:
if u.typ.base == upField.typ.base:
result.add(newAsgnStmt(rawIndirectAccess(vnode, upField, iter.info),
u, iter.info))
else: