| Something I've pondered is adding a more-expressive form of RULES which
| works using general pattern matching:
Yes, but it would need the rule-matcher in the Simplifier to be more
sophisticated. Have a look in specialise/Rules.lhs.
No need to be so ambitious; just moving towards what you can do in PrelRules
would be an improvement
Simon
|
| {-# XRULES
| "*#-to-shift" (*#)
| (CoreLit (CoreInt num)) obj
| | num .&. (num - 1) == 0 ->
| CoreApp (CoreVar "GHC.Prim.iShiftL#")
| [obj, CoreLit (CoreInt (lg2 num))]
| obj (CoreLit (CoreInt num))
| | num .&. (num - 1) == 0 ->
| CoreApp (CoreVar "GHC.Prim.iShiftL#")
| [obj, CoreLit (CoreInt (lg2 num))]
| #-}
|
| This would require reusing the TH infrastructure, and (depending on how
| much we can abstract) might leak too many details of Core to be
| useful; on the other hand it would allow some very interesting domain
| optimizations to be done.
|
| Views might be nice here.
|
| Opinions on whether something like this is a good idea?
|
| Stefan
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