closure implementation: first steps
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Araq
parent
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commit
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10 changed files with 330 additions and 299 deletions
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@ -220,7 +220,7 @@ type
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sfDiscriminant, # field is a discriminant in a record/object
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sfDeprecated, # symbol is deprecated
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sfError, # usage of symbol should trigger a compile-time error
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sfInClosure, # variable is accessed by a closure
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sfInnerProc, # proc is an inner proc
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sfThread, # proc will run as a thread
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# variable is a thread variable
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sfCompileTime, # proc can be evaluated at compile time
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@ -976,6 +976,13 @@ proc hasSonWith(n: PNode, kind: TNodeKind): bool =
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return true
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result = false
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proc containsNode*(n: PNode, kinds: TNodeKinds): bool =
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case n.kind
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of nkEmpty..nkNilLit: result = n.kind in kinds
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else:
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for i in countup(0, sonsLen(n) - 1):
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if containsNode(n.sons[i], kinds): return true
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proc hasSubnodeWith(n: PNode, kind: TNodeKind): bool =
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case n.kind
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of nkEmpty..nkNilLit: result = n.kind == kind
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@ -1030,3 +1037,6 @@ proc isGenericRoutine*(s: PSym): bool =
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result = s.ast != nil and s.ast[genericParamsPos].kind != nkEmpty
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else: nil
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iterator items*(n: PNode): PNode =
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for i in 0.. <n.len: yield n.sons[i]
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201
compiler/lambdalifting.nim
Normal file
201
compiler/lambdalifting.nim
Normal file
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@ -0,0 +1,201 @@
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#
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#
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# The Nimrod Compiler
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# (c) Copyright 2012 Andreas Rumpf
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#
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# See the file "copying.txt", included in this
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# distribution, for details about the copyright.
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#
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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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# 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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deref.typ = x.typ.sons[0]
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addSon(deref, x)
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result = newNodeI(nkDotExpr, x.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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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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proc gatherVars(c: PTransf, n: PNode, owner: PSym, container: PNode) =
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# gather used vars for closure generation
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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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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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incl(container, s)
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of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: nil
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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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proc replaceVars(c: PTransf, n: PNode, owner, 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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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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# access through the closure param:
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n.sons[i] = indirectAccess(env, s)
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else:
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replaceVars(c, n.sons[i], owner, env)
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proc addFormalParam(routine: PSym, param: PSym) =
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addSon(routine.typ, param.typ)
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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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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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proc searchForInnerProcs(c: PTransf, n: PNode, owner: PSym, container: PNode) =
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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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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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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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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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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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# 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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# 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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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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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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# '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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result = newTransNode(nkStmtList, env.info, 0)
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var v = newNodeI(nkVarSection, env.info)
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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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# 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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# 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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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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return PTransNode(n)
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var s = n.sons[namePos].sym
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var body = s.getBody
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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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var closure = newNodeI(nkRecList, n.info)
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searchForInnerProcs(c, body, s, closure)
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if closure.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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# 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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# 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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var envSym = newTemp(c, envType, s.info)
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var newBody = createEnvStmt(c, closure, 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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# now we can transform 'body' as all rewriting entries have been created.
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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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proc generateThunk(c: PTransf, prc: PNode, closure: 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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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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@ -212,8 +212,8 @@ proc procTypeRel(mapping: var TIdTable, f, a: PType): TTypeRelation =
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case a.kind
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of tyNil: result = isSubtype
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of tyProc:
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if sonsLen(f) != sonsLen(a) or f.callconv != a.callconv: return
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of tyProc:
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if sonsLen(f) != sonsLen(a): return
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# Note: We have to do unification for the parameters before the
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# return type!
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result = isEqual # start with maximum; also correct for no
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@ -240,6 +240,12 @@ proc procTypeRel(mapping: var TIdTable, f, a: PType): TTypeRelation =
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elif tfThread in f.flags and a.flags * {tfThread, tfNoSideEffect} == {}:
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# noSideEffect implies ``tfThread``! XXX really?
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result = isNone
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elif f.callconv != a.callconv:
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# valid to pass a 'nimcall' thingie to 'closure':
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if f.callconv == ccClosure and a.callconv == ccDefault:
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result = isConvertible
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else:
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result = isNone
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else: nil
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proc typeRel(mapping: var TIdTable, f, a: PType): TTypeRelation =
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@ -45,7 +45,8 @@ type
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transCon: PTransCon # top of a TransCon stack
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inlining: int # > 0 if we are in inlining context (copy vars)
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blocksyms: seq[PSym]
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procToEnv: TIdTable # mapping from a proc to its generated explicit
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# 'env' var (for closure generation)
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PTransf = ref TTransfContext
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proc newTransNode(a: PNode): PTransNode {.inline.} =
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@ -502,77 +503,14 @@ proc transformFor(c: PTransf, n: PNode): PTransNode =
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popTransCon(c)
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#echo "transformed: ", renderTree(n)
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proc getMagicOp(call: PNode): TMagic =
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if call.sons[0].kind == nkSym and
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call.sons[0].sym.kind in {skProc, skMethod, skConverter}:
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result = call.sons[0].sym.magic
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else:
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result = mNone
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proc gatherVars(c: PTransf, n: PNode, marked: var TIntSet, owner: PSym,
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container: PNode) =
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# gather used vars for closure generation
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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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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 and not ContainsOrIncl(marked, s.id):
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incl(s.flags, sfInClosure)
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addSon(container, copyNode(n)) # DON'T make a copy of the symbol!
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of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit:
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nil
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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], marked, owner, container)
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proc addFormalParam(routine: PSym, param: PSym) =
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addSon(routine.typ, param.typ)
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addSon(routine.ast.sons[paramsPos], newSymNode(param))
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proc indirectAccess(a, b: PSym): 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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deref.typ = x.typ.sons[0]
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addSon(deref, x)
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result = newNodeI(nkDotExpr, x.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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proc transformLambda(c: PTransf, n: PNode): PNode =
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var marked = initIntSet()
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result = n
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if n.sons[namePos].kind != nkSym: InternalError(n.info, "transformLambda")
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var s = n.sons[namePos].sym
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var closure = newNodeI(nkRecList, n.info)
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var body = s.getBody
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gatherVars(c, body, marked, s, closure)
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# add closure type to the param list (even if closure is empty!):
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var cl = newType(tyObject, s)
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cl.n = closure
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addSon(cl, nil) # no super class
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var p = newType(tyRef, s)
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addSon(p, cl)
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var param = newSym(skParam, getIdent(genPrefix & "Cl"), s)
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param.typ = p
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addFormalParam(s, param)
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# all variables that are accessed should be accessed by the new closure
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# parameter:
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if sonsLen(closure) > 0:
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var newC = newTransCon(c.transCon.owner)
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for i in countup(0, sonsLen(closure) - 1):
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IdNodeTablePut(newC.mapping, closure.sons[i].sym,
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indirectAccess(param, closure.sons[i].sym))
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pushTransCon(c, newC)
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n.sons[bodyPos] = transform(c, body).pnode
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popTransCon(c)
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include lambdalifting
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proc transformCase(c: PTransf, n: PNode): PTransNode =
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# removes `elif` branches of a case stmt
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@ -670,23 +608,10 @@ proc transform(c: PTransf, n: PNode): PTransNode =
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of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit:
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# nothing to be done for leaves:
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result = PTransNode(n)
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of nkBracketExpr:
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result = transformArrayAccess(c, n)
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of nkLambda:
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var s = n.sons[namePos].sym
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n.sons[bodyPos] = PNode(transform(c, s.getBody))
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result = PTransNode(n)
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when false: result = transformLambda(c, n)
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of nkForStmt:
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result = transformFor(c, n)
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of nkCaseStmt:
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result = transformCase(c, n)
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of nkProcDef, nkMethodDef, nkIteratorDef, nkMacroDef, nkConverterDef:
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if n.sons[genericParamsPos].kind == nkEmpty:
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var s = n.sons[namePos].sym
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n.sons[bodyPos] = PNode(transform(c, s.getBody))
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if n.kind == nkMethodDef: methodDef(s, false)
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result = PTransNode(n)
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of nkBracketExpr: result = transformArrayAccess(c, n)
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of procDefs: result = transformProc(c, n)
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of nkForStmt: result = transformFor(c, n)
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of nkCaseStmt: result = transformCase(c, n)
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of nkContinueStmt:
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result = PTransNode(newNode(nkBreakStmt))
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var labl = c.blockSyms[c.blockSyms.high]
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@ -748,6 +673,7 @@ proc openTransf(module: PSym, filename: string): PPassContext =
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new(n)
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n.blocksyms = @[]
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n.module = module
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initIdTable(n.procToEnv)
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result = n
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proc openTransfCached(module: PSym, filename: string,
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