patch applied (ghc): Semi-tagging optimisation

[Simon Marlow]

Simon Marlow wrote:
> Mon Jan 22 03:40:16 PST 2007  Simon Marlow <simonmar at microsoft.com>
>   UNDO: Semi-tagging optimisation
>   In the generated code for case-of-variable, test the tag of the
>   scrutinee closure and only enter if it is unevaluated.  Also turn
>   *off* vectored returns.
> 
>     M ./compiler/codeGen/CgCallConv.hs -4 +3
>     M ./compiler/codeGen/CgCase.lhs -87 +12
>     M ./compiler/codeGen/CgInfoTbls.hs -1 +1
>     M ./compiler/codeGen/CgTailCall.lhs -1 +1
>     M ./compiler/codeGen/CgUtils.hs -3

Sorry folks, I pushed this by accident.  It's not ready yet.

Cheers,
	Simon