LabelDef parameters - previously defined vs new

[Vlad Ureche]

Hi,

I've been working on SI-5788 and I stumbled upon two very different ways LabelDefs are generated:
 - if generated by the tailcalls phase, their parameters are existing symbols defined in the code before the tailcall
 - if generated by the virtualized pattern matcher, their parameters are new symbols, appearing there for the first time
Gist here - look for BEHAVIOR1 and BEHAVIOR2 for a quick lookup.

My question is: what should be the behavior of LabelDefs? Should they pick up existing symbols or not?

Thanks,
Vlad

[Adriaan Moors]

On Wed, May 16, 2012 at 1:51 PM, Vlad Ureche <vlad....@gmail.com> wrote:

Hi,

I've been working on SI-5788 and I stumbled upon two very different ways LabelDefs are generated:

really?

they seem to be generated quite similarly

 - if generated by the tailcalls phase, their parameters are existing symbols defined in the code before the tailcall

          val label     = method.newLabel(newTermName("_" + method.name), method.pos)

          val thisParam = method.newSyntheticValueParam(currentClass.typeOfThis)

          label setInfo MethodType(thisParam :: method.tpe.params, method.tpe.finalResultType)

 

 - if generated by the virtualized pattern matcher, their parameters are new symbols, appearing there for the first time

        val matchEnd = NoSymbol.newLabel(freshName("matchEnd"), NoPosition) setFlag SYNTH_CASE

        val matchRes = NoSymbol.newValueParameter(newTermName("x"), NoPosition, SYNTHETIC) setInfo restpe.withoutAnnotations //

        matchEnd setInfo MethodType(List(matchRes), restpe)

ignore the NoSymbol -- the owner is changed later (yes, I know, this needs to be fixed, and I will get to that)

[Adriaan Moors]

ah whoops, i missed the ` :: method.tpe.params`, sorry about that

so the same label has one symbol that's created for it, and reuses the parameters from the method

that seems pretty icky to me