• simonpj@microsoft.com's avatar
    Major improvement to SpecConstr · cac2aca1
    simonpj@microsoft.com authored
    This patch improves the SpecConstr pass, by 
      a) making it work with join points
      b) making it generate specialisations transitively
    As part of it, SpecConstr now carries a substitution with it, which
    runs over the whole program as it goes.  This turned out to be 
    a big win; simplified the implementation quite a bit.
    I have *disabled* the specialisation on lambdas; it's pretty fragile,
    and sometimes generates more and more specialisations. Something to
    come back to, perhaps.
    I rejigged the flag-handling a bit.  Now the specification of passes
    in DynFlags is a bit nicer; see
    	- optLevelFlags top-level data structure
    	- runWhen function
    	- CoreDoPasses constructor
    There are now command-line flags
    which do the obvious thing.  -O2 switches on both spec-constr and liberate-case.
    You can use -fno-liberate-case, -fno-spec-constr after -O2 to switch them off again.
    The spec-threshold applies to both these transformations; default value 200 for now.