further steps to closure support
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Araq
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20 changed files with 379 additions and 138 deletions
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@ -9,34 +9,46 @@
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# This include file implements lambda lifting for the transformator.
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# - Things to consider: Does capturing of 'result' work? (unknown)
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# - Do generic inner procs work? (should)
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# - Does nesting of closures work? (not yet)
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# - Test that iterators within closures work etc.
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const
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procDefs = {nkLambda, nkProcDef, nkMethodDef, nkIteratorDef, nkMacroDef,
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nkConverterDef}
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proc indirectAccess(a, b: PSym): PNode =
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proc indirectAccess(a, b: PSym, info: TLineInfo): PNode =
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# returns a[].b as a node
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var x = newSymNode(a)
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var y = newSymNode(b)
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var deref = newNodeI(nkHiddenDeref, x.info)
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let x = newSymNode(a)
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var deref = newNodeI(nkHiddenDeref, info)
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deref.typ = x.typ.sons[0]
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let field = getSymFromList(deref.typ.n, b.name)
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addSon(deref, x)
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result = newNodeI(nkDotExpr, x.info)
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result = newNodeI(nkDotExpr, info)
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addSon(result, deref)
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addSon(result, y)
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result.typ = y.typ
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addSon(result, newSymNode(field))
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result.typ = field.typ
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proc Incl(container: PNode, s: PSym) =
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for x in container:
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if x.sym.id == s.id: return
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container.add(newSymNode(s))
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type
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TCapture = seq[PSym]
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proc gatherVars(c: PTransf, n: PNode, owner: PSym, container: PNode) =
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# gather used vars for closure generation
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proc Capture(cap: var TCapture, s: PSym) =
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for x in cap:
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if x.name.id == s.name.id: return
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cap.add(s)
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proc captureToTuple(cap: TCapture, owner: PSym): PType =
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result = newType(tyTuple, owner)
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result.n = newNodeI(nkRecList, owner.info)
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for s in cap:
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var field = newSym(skField, s.name, s.owner)
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let typ = s.typ
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field.typ = typ
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field.position = sonsLen(result)
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addSon(result.n, newSymNode(field))
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addSon(result, typ)
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proc gatherVars(c: PTransf, n: PNode, outerProc: PSym, cap: var TCapture) =
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# gather used vars for closure generation into 'cap'
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case n.kind
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of nkSym:
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var s = n.sym
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@ -45,82 +57,88 @@ proc gatherVars(c: PTransf, n: PNode, owner: PSym, container: PNode) =
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of skVar, skLet: found = sfGlobal notin s.flags
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of skTemp, skForVar, skParam, skResult: found = true
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else: nil
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if found and owner.id != s.owner.id:
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incl(container, s)
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if found and outerProc.id == s.owner.id:
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#echo "captured: ", s.name.s
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Capture(cap, s)
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of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: nil
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else:
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else:
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for i in countup(0, sonsLen(n) - 1):
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gatherVars(c, n.sons[i], owner, container)
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gatherVars(c, n.sons[i], outerProc, cap)
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proc replaceVars(c: PTransf, n: PNode, owner, env: PSym) =
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proc replaceVars(c: PTransf, n: PNode, outerProc, env: PSym) =
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for i in countup(0, safeLen(n) - 1):
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if n.kind == nkSym:
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let s = n.sym
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let a = n.sons[i]
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if a.kind == nkSym:
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let s = a.sym
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var found = false
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case s.kind
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of skVar, skLet: found = sfGlobal notin s.flags
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of skTemp, skForVar, skParam, skResult: found = true
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else: nil
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if found and owner.id != s.owner.id:
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if found and outerProc.id == s.owner.id:
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# access through the closure param:
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n.sons[i] = indirectAccess(env, s)
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n.sons[i] = indirectAccess(env, s, n.info)
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else:
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replaceVars(c, n.sons[i], owner, env)
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replaceVars(c, a, outerProc, env)
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proc addFormalParam(routine: PType, param: PSym) =
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addSon(routine, param.typ)
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addSon(routine.n, newSymNode(param))
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proc addFormalParam(routine: PSym, param: PSym) =
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addSon(routine.typ, param.typ)
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#addFormalParam(routine.typ, param)
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addSon(routine.ast.sons[paramsPos], newSymNode(param))
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proc isInnerProc(s, owner: PSym): bool {.inline.} =
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proc isInnerProc(s, outerProc: PSym): bool {.inline.} =
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result = s.kind in {skProc, skMacro, skIterator, skMethod, skConverter} and
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s.owner.id == owner.id and not isGenericRoutine(s)
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s.owner.id == outerProc.id and not isGenericRoutine(s) and
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s.typ.callConv == ccClosure
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proc searchForInnerProcs(c: PTransf, n: PNode, owner: PSym, container: PNode) =
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proc searchForInnerProcs(c: PTransf, n: PNode, outerProc: PSym,
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cap: var TCapture) =
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case n.kind
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of nkSym:
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let s = n.sym
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if isInnerProc(s, owner):
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gatherVars(c, s.getBody, owner, container)
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if isInnerProc(s, outerProc):
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gatherVars(c, s.getBody, outerProc, cap)
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of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: nil
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else:
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for i in 0.. <len(n):
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searchForInnerProcs(c, n.sons[i], owner, container)
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searchForInnerProcs(c, n.sons[i], outerProc, cap)
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proc makeClosure(c: PTransf, prc, env: PSym): PNode =
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var tup = newType(tyTuple, c.module)
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tup.addson(prc.typ)
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tup.addson(env.typ)
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result = newNodeIT(nkPar, prc.info, tup)
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proc makeClosure(c: PTransf, prc, env: PSym, info: TLineInfo): PNode =
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result = newNodeIT(nkClosure, info, prc.typ)
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result.add(newSymNode(prc))
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result.add(newSymNode(env))
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proc transformInnerProcs(c: PTransf, n: PNode, owner, env: PSym) =
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proc transformInnerProcs(c: PTransf, n: PNode, outerProc, env: PSym) =
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case n.kind
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of nkSym:
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let innerProc = n.sym
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if isInnerProc(innerProc, owner):
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if isInnerProc(innerProc, outerProc):
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# inner proc could capture outer vars:
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var param = newTemp(c, env.typ, n.info)
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param.kind = skParam
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addFormalParam(innerProc, param)
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# 'anon' should be replaced by '(anon, env)':
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IdNodeTablePut(c.transCon.mapping, innerProc,
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makeClosure(c, innerProc, env))
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makeClosure(c, innerProc, env, n.info))
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# access all non-local vars through the 'env' param:
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var body = innerProc.getBody
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replaceVars(c, body, innerProc, param)
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# XXX does not work with recursion!
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replaceVars(c, body, outerProc, param)
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innerProc.ast.sons[bodyPos] = body
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of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: nil
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else:
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for i in 0.. <len(n):
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transformInnerProcs(c, n.sons[i], owner, env)
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transformInnerProcs(c, n.sons[i], outerProc, env)
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proc newCall(a, b: PSym): PNode =
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result = newNodeI(nkCall, a.info)
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result.add newSymNode(a)
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result.add newSymNode(b)
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proc createEnvStmt(c: PTransf, varList: PNode, env: PSym): PTransNode =
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proc createEnvStmt(c: PTransf, varList: TCapture, env: PSym): PTransNode =
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# 'varlist' can contain parameters or variables. We don't eliminate yet
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# local vars that end up in an environment. This could even be a for loop
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# var!
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@ -129,17 +147,33 @@ proc createEnvStmt(c: PTransf, varList: PNode, env: PSym): PTransNode =
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addVar(v, newSymNode(env))
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result.add(v.ptransNode)
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# add 'new' statement:
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result.add(newCall(getSysSym"new", env).ptransnode)
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result.add(newCall(getSysSym"internalNew", env).ptransnode)
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# add assignment statements:
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for v in varList:
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assert v.kind == nkSym
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let fieldAccess = indirectAccess(env, v.sym)
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if v.sym.kind == skParam:
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let fieldAccess = indirectAccess(env, v, env.info)
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if v.kind == skParam:
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# add ``env.param = param``
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result.add(newAsgnStmt(c, fieldAccess, v.ptransNode))
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IdNodeTablePut(c.transCon.mapping, v.sym, fieldAccess)
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result.add(newAsgnStmt(c, fieldAccess, newSymNode(v).ptransNode))
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IdNodeTablePut(c.transCon.mapping, v, fieldAccess)
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proc transformProcFin(c: PTransf, n: PNode, s: PSym): PTransNode =
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# to be safe: XXX this a mystery how it could ever happen that: s.ast != n.
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s.ast.sons[bodyPos] = n.sons[bodyPos]
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if n.kind == nkMethodDef: methodDef(s, false)
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# should 's' be replaced by a tuple ('s', env)?
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var tc = c.transCon
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var repl: PNode = nil
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while tc != nil:
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repl = IdNodeTableGet(tc.mapping, s)
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if repl != nil: break
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tc = tc.next
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if repl != nil:
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result = PTransNode(repl)
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else:
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result = PTransNode(n)
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proc transformProc(c: PTransf, n: PNode): PTransNode =
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# don't process generics:
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if n.sons[genericParamsPos].kind != nkEmpty:
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@ -147,34 +181,32 @@ proc transformProc(c: PTransf, n: PNode): PTransNode =
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var s = n.sons[namePos].sym
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var body = s.getBody
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if body.kind == nkEmpty:
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return PTransNode(n)
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if not containsNode(body, procDefs):
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# fast path: no inner procs, so no closure needed:
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n.sons[bodyPos] = PNode(transform(c, body))
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if n.kind == nkMethodDef: methodDef(s, false)
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return PTransNode(n)
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return transformProcFin(c, n, s)
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var closure = newNodeI(nkRecList, n.info)
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searchForInnerProcs(c, body, s, closure)
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# create environment:
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var cap: TCapture = @[]
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searchForInnerProcs(c, body, s, cap)
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if closure.len == 0:
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if cap.len == 0:
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# fast path: no captured variables, so no closure needed:
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n.sons[bodyPos] = PNode(transform(c, body))
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if n.kind == nkMethodDef: methodDef(s, false)
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return PTransNode(n)
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return transformProcFin(c, n, s)
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# create environment:
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var envDesc = newType(tyObject, s)
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envDesc.n = closure
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addSon(envDesc, nil) # no super class
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var envType = newType(tyRef, s)
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addSon(envType, envDesc)
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addSon(envType, captureToTuple(cap, s))
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# XXX currently we always do a heap allocation. A simple escape analysis
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# could turn the closure into a stack allocation. Later versions will
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# implement that.
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# Currently we always do a heap allocation. A simple escape analysis
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# could turn the closure into a stack allocation. Later versions might
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# implement that. This would require backend changes too though.
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var envSym = newTemp(c, envType, s.info)
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var newBody = createEnvStmt(c, closure, envSym)
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var newBody = createEnvStmt(c, cap, envSym)
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# modify any local proc to gain a new parameter; this also creates the
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# mapping entries that turn (localProc) into (localProc, env):
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transformInnerProcs(c, body, s, envSym)
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@ -183,19 +215,18 @@ proc transformProc(c: PTransf, n: PNode): PTransNode =
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# Careful this transforms the inner procs too!
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newBody.add(transform(c, body))
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n.sons[bodyPos] = newBody.pnode
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if n.kind == nkMethodDef: methodDef(s, false)
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result = newBody
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result = transformProcFin(c, n, s)
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proc generateThunk(c: PTransf, prc: PNode, closure: PType): PNode =
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proc generateThunk(c: PTransf, prc: PNode, dest: PType): PNode =
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## Converts 'prc' into '(thunk, nil)' so that it's compatible with
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## a closure.
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# XXX we hack around here by generating a 'cast' instead of a proper thunk.
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result = newNodeIT(nkPar, prc.info, closure)
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var conv = newNodeIT(nkHiddenStdConv, prc.info, closure.sons[0])
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result = newNodeIT(nkClosure, prc.info, dest)
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var conv = newNodeIT(nkHiddenStdConv, prc.info, dest)
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conv.add(emptyNode)
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conv.add(prc)
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result.add(conv)
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result.add(newNodeIT(nkNilLit, prc.info, closure.sons[1]))
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result.add(newNodeIT(nkNilLit, prc.info, getSysType(tyNil)))
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