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Diffstat (limited to 'src/compiler/scala/tools/nsc/transform/LazyVals.scala')
| -rw-r--r-- | src/compiler/scala/tools/nsc/transform/LazyVals.scala | 293 |
1 files changed, 0 insertions, 293 deletions
diff --git a/src/compiler/scala/tools/nsc/transform/LazyVals.scala b/src/compiler/scala/tools/nsc/transform/LazyVals.scala deleted file mode 100644 index b6695efb0b..0000000000 --- a/src/compiler/scala/tools/nsc/transform/LazyVals.scala +++ /dev/null @@ -1,293 +0,0 @@ -package scala.tools.nsc -package transform - -import scala.collection.{ mutable, immutable } - -abstract class LazyVals extends Transform with TypingTransformers with ast.TreeDSL { - // inherits abstract value `global` and class `Phase` from Transform - - import global._ // the global environment - import definitions._ // standard classes and methods - import typer.{typed, atOwner} // methods to type trees - import CODE._ - - val phaseName: String = "lazyvals" - private val FLAGS_PER_BYTE: Int = 8 // Byte - private def bitmapKind = ByteClass - - def newTransformer(unit: CompilationUnit): Transformer = - new LazyValues(unit) - - private def lazyUnit(sym: Symbol) = sym.tpe.resultType.typeSymbol == UnitClass - - object LocalLazyValFinder extends Traverser { - var result: Boolean = _ - - def find(t: Tree) = {result = false; traverse(t); result} - def find(ts: List[Tree]) = {result = false; traverseTrees(ts); result} - - override def traverse(t: Tree) { - if (!result) - t match { - case v@ValDef(_, _, _, _) if v.symbol.isLazy => - result = true - - case d@DefDef(_, _, _, _, _, _) if d.symbol.isLazy && lazyUnit(d.symbol) => - d.symbol.resetFlag(symtab.Flags.LAZY) - result = true - - case ClassDef(_, _, _, _) | DefDef(_, _, _, _, _, _) | ModuleDef(_, _, _) => - - case LabelDef(name, _, _) if nme.isLoopHeaderLabel(name) => - - case _ => - super.traverse(t) - } - } - } - - /** - * Transform local lazy accessors to check for the initialized bit. - */ - class LazyValues(unit: CompilationUnit) extends TypingTransformer(unit) { - /** map from method symbols to the number of lazy values it defines. */ - private val lazyVals = perRunCaches.newMap[Symbol, Int]() withDefaultValue 0 - - import symtab.Flags._ - - /** Perform the following transformations: - * - for a lazy accessor inside a method, make it check the initialization bitmap - * - for all methods, add enough int vars to allow one flag per lazy local value - * - blocks in template bodies behave almost like methods. A single bitmaps section is - * added in the first block, for all lazy values defined in such blocks. - * - remove ACCESSOR flags: accessors in traits are not statically implemented, - * but moved to the host class. local lazy values should be statically implemented. - */ - override def transform(tree: Tree): Tree = { - val sym = tree.symbol - curTree = tree - - tree match { - - case Block(_, _) => - val block1 = super.transform(tree) - val Block(stats, expr) = block1 - val stats1 = stats.flatMap(_ match { - case Block(List(d1@DefDef(_, n1, _, _, _, _)), d2@DefDef(_, n2, _, _, _, _)) if (nme.newLazyValSlowComputeName(n2) == n1) => - List(d1, d2) - case stat => - List(stat) - }) - treeCopy.Block(block1, stats1, expr) - - case DefDef(_, _, _, _, _, rhs) => atOwner(tree.symbol) { - val (res, slowPathDef) = if (!sym.owner.isClass && sym.isLazy) { - val enclosingClassOrDummyOrMethod = { - val enclMethod = sym.enclMethod - - if (enclMethod != NoSymbol ) { - val enclClass = sym.enclClass - if (enclClass != NoSymbol && enclMethod == enclClass.enclMethod) - enclClass - else - enclMethod - } else - sym.owner - } - debuglog(s"determined enclosing class/dummy/method for lazy val as $enclosingClassOrDummyOrMethod given symbol $sym") - val idx = lazyVals(enclosingClassOrDummyOrMethod) - lazyVals(enclosingClassOrDummyOrMethod) = idx + 1 - val (rhs1, sDef) = mkLazyDef(enclosingClassOrDummyOrMethod, transform(rhs), idx, sym) - sym.resetFlag((if (lazyUnit(sym)) 0 else LAZY) | ACCESSOR) - (rhs1, sDef) - } else - (transform(rhs), EmptyTree) - - val ddef1 = deriveDefDef(tree)(_ => if (LocalLazyValFinder.find(res)) typed(addBitmapDefs(sym, res)) else res) - if (slowPathDef != EmptyTree) Block(slowPathDef, ddef1) else ddef1 - } - - case Template(_, _, body) => atOwner(currentOwner) { - val body1 = super.transformTrees(body) - var added = false - val stats = - for (stat <- body1) yield stat match { - case Block(_, _) | Apply(_, _) | If(_, _, _) | Try(_, _, _) if !added => - // Avoid adding bitmaps when they are fully overshadowed by those - // that are added inside loops - if (LocalLazyValFinder.find(stat)) { - added = true - typed(addBitmapDefs(sym, stat)) - } else stat - case ValDef(_, _, _, _) => - typed(deriveValDef(stat)(addBitmapDefs(stat.symbol, _))) - case _ => - stat - } - val innerClassBitmaps = if (!added && currentOwner.isClass && bitmaps.contains(currentOwner)) { - // add bitmap to inner class if necessary - val toAdd0 = bitmaps(currentOwner).map(s => typed(ValDef(s, ZERO))) - toAdd0.foreach(t => { - if (currentOwner.info.decl(t.symbol.name) == NoSymbol) { - t.symbol.setFlag(PROTECTED) - currentOwner.info.decls.enter(t.symbol) - } - }) - toAdd0 - } else List() - deriveTemplate(tree)(_ => innerClassBitmaps ++ stats) - } - - case ValDef(_, _, _, _) if !sym.owner.isModule && !sym.owner.isClass => - deriveValDef(tree) { rhs0 => - val rhs = transform(rhs0) - if (LocalLazyValFinder.find(rhs)) typed(addBitmapDefs(sym, rhs)) else rhs - } - - case l@LabelDef(name0, params0, ifp0@If(_, _, _)) if name0.startsWith(nme.WHILE_PREFIX) => - val ifp1 = super.transform(ifp0) - val If(cond0, thenp0, elsep0) = ifp1 - - if (LocalLazyValFinder.find(thenp0)) - deriveLabelDef(l)(_ => treeCopy.If(ifp1, cond0, typed(addBitmapDefs(sym.owner, thenp0)), elsep0)) - else - l - - case l@LabelDef(name0, params0, block@Block(stats0, expr)) - if name0.startsWith(nme.WHILE_PREFIX) || name0.startsWith(nme.DO_WHILE_PREFIX) => - val stats1 = super.transformTrees(stats0) - if (LocalLazyValFinder.find(stats1)) - deriveLabelDef(l)(_ => treeCopy.Block(block, typed(addBitmapDefs(sym.owner, stats1.head))::stats1.tail, expr)) - else - l - - case _ => super.transform(tree) - } - } - - /** Add the bitmap definitions to the rhs of a method definition. - * If the rhs has been tail-call transformed, insert the bitmap - * definitions inside the top-level label definition, so that each - * iteration has the lazy values uninitialized. Otherwise add them - * at the very beginning of the method. - */ - private def addBitmapDefs(methSym: Symbol, rhs: Tree): Tree = { - def prependStats(stats: List[Tree], tree: Tree): Block = tree match { - case Block(stats1, res) => Block(stats ::: stats1, res) - case _ => Block(stats, tree) - } - - val bmps = bitmaps(methSym) map (ValDef(_, ZERO)) - - def isMatch(params: List[Ident]) = (params.tail corresponds methSym.tpe.params)(_.tpe == _.tpe) - - if (bmps.isEmpty) rhs else rhs match { - case Block(assign, l @ LabelDef(name, params, _)) - if (name string_== "_" + methSym.name) && isMatch(params) => - Block(assign, deriveLabelDef(l)(rhs => typed(prependStats(bmps, rhs)))) - - case _ => prependStats(bmps, rhs) - } - } - - def mkSlowPathDef(clazz: Symbol, lzyVal: Symbol, cond: Tree, syncBody: List[Tree], - stats: List[Tree], retVal: Tree): Tree = { - // Q: is there a reason to first set owner to `clazz` (by using clazz.newMethod), and then - // changing it to lzyVal.owner very soon after? Could we just do lzyVal.owner.newMethod? - val defSym = clazz.newMethod(nme.newLazyValSlowComputeName(lzyVal.name.toTermName), lzyVal.pos, STABLE | PRIVATE) - defSym setInfo MethodType(List(), lzyVal.tpe.resultType) - defSym.owner = lzyVal.owner - debuglog(s"crete slow compute path $defSym with owner ${defSym.owner} for lazy val $lzyVal") - if (bitmaps.contains(lzyVal)) - bitmaps(lzyVal).map(_.owner = defSym) - val rhs: Tree = gen.mkSynchronizedCheck(clazz, cond, syncBody, stats).changeOwner(currentOwner -> defSym) - - DefDef(defSym, addBitmapDefs(lzyVal, BLOCK(rhs, retVal))) - } - - - def mkFastPathBody(clazz: Symbol, lzyVal: Symbol, cond: Tree, syncBody: List[Tree], - stats: List[Tree], retVal: Tree): (Tree, Tree) = { - val slowPathDef: Tree = mkSlowPathDef(clazz, lzyVal, cond, syncBody, stats, retVal) - (If(cond, Apply(Ident(slowPathDef.symbol), Nil), retVal), slowPathDef) - } - - /** return a 'lazified' version of rhs. Rhs should conform to the - * following schema: - * { - * l$ = <rhs> - * l$ - * } or - * <rhs> when the lazy value has type Unit (for which there is no field - * to cache its value. - * - * Similarly as for normal lazy val members (see Mixin), the result will be a tree of the form - * { if ((bitmap&n & MASK) == 0) this.l$compute() - * else l$ - * - * def l$compute() = { synchronized(enclosing_class_or_dummy) { - * if ((bitmap$n & MASK) == 0) { - * l$ = <rhs> - * bitmap$n = bimap$n | MASK - * }} - * l$ - * } - * } - * where bitmap$n is a byte value acting as a bitmap of initialized values. It is - * the 'n' is (offset / 8), the MASK is (1 << (offset % 8)). If the value has type - * unit, no field is used to cache the value, so the l$compute will now look as following: - * { - * def l$compute() = { synchronized(enclosing_class_or_dummy) { - * if ((bitmap$n & MASK) == 0) { - * <rhs>; - * bitmap$n = bimap$n | MASK - * }} - * () - * } - * } - */ - private def mkLazyDef(methOrClass: Symbol, tree: Tree, offset: Int, lazyVal: Symbol): (Tree, Tree) = { - val bitmapSym = getBitmapFor(methOrClass, offset) - val mask = LIT(1 << (offset % FLAGS_PER_BYTE)) - val bitmapRef = if (methOrClass.isClass) Select(This(methOrClass), bitmapSym) else Ident(bitmapSym) - - def mkBlock(stmt: Tree) = BLOCK(stmt, mkSetFlag(bitmapSym, mask, bitmapRef), UNIT) - - debuglog(s"create complete lazy def in $methOrClass for $lazyVal") - val (block, res) = tree match { - case Block(List(assignment), res) if !lazyUnit(lazyVal) => - (mkBlock(assignment), res) - case rhs => - (mkBlock(rhs), UNIT) - } - - val cond = (bitmapRef GEN_& (mask, bitmapKind)) GEN_== (ZERO, bitmapKind) - val lazyDefs = mkFastPathBody(methOrClass.enclClass, lazyVal, cond, List(block), Nil, res) - (atPos(tree.pos)(localTyper.typed {lazyDefs._1 }), atPos(tree.pos)(localTyper.typed {lazyDefs._2 })) - } - - private def mkSetFlag(bmp: Symbol, mask: Tree, bmpRef: Tree): Tree = - bmpRef === (bmpRef GEN_| (mask, bitmapKind)) - - val bitmaps = mutable.Map[Symbol, List[Symbol]]() withDefaultValue Nil - - /** Return the symbol corresponding of the right bitmap int inside meth, - * given offset. - */ - private def getBitmapFor(meth: Symbol, offset: Int): Symbol = { - val n = offset / FLAGS_PER_BYTE - val bmps = bitmaps(meth) - if (bmps.length > n) - bmps(n) - else { - val sym = meth.newVariable(nme.newBitmapName(nme.BITMAP_NORMAL, n), meth.pos).setInfo(ByteTpe) - enteringTyper { - sym addAnnotation VolatileAttr - } - - bitmaps(meth) = (sym :: bmps).reverse - sym - } - } - } -} |