Two Hoopl questions

[Simon Peyton-Jones]

Yes it'll generate two uniques.  I think that's fine.  

Simon

|  -----Original Message-----
|  From: ghc-devs [mailto:ghc-devs-bounces at haskell.org] On Behalf Of Jan Stolarek
|  Sent: 26 July 2013 16:56
|  To: ghc-devs
|  Subject: Re: Two Hoopl questions
|  
|  OK, let's make it "Three Hoopl questions".
|  
|  3) Consider this rewriting function:
|  
|  cpRwMiddle dflags (CmmStore lhs rhs) _ = do
|    u <- getUniqueUs
|    let regSize      = cmmExprType dflags rhs
|        newReg       = CmmLocal $ LocalReg u regSize
|        newRegAssign = CmmAssign newReg rhs
|        newMemAssign = CmmStore lhs (CmmReg newReg)
|    return . Just . GUnit . BCons newRegAssign . BMiddle $ newMemAssign
|  
|  Is this a correct way of generating new Uniques? If this function is evaluated twice
|  will it generate two different uniques?
|  
|  Janek
|  
|  ----- Oryginalna wiadomość -----
|  Od: "Jan Stolarek" <jan.stolarek at p.lodz.pl>
|  Do: "ghc-devs" <ghc-devs at haskell.org>
|  Wysłane: piątek, 26 lipiec 2013 10:50:01
|  Temat: Two Hoopl questions
|  
|  I have two questions about using Hoopl:
|  
|  1) I'm debugging some Hoopl transformations that often fall into an infinite loop.
|  Probably the easiest way to find the cause would be to allow only a limited number
|  of iterations and then examining the rewritten output. I think that optimization
|  fuel was designed exactly with this scenario in mind, but Compiler.Hoopl module
|  in hoopl library does not re-export functions needed to use Fuel (e.g.
|  runWithFuel). Why are these functions hidden? Is there another interface for using
|  fuel?
|  
|  2) In my algorithm I need to initialize all of the blocks in a graph with bottom
|  element of a lattice, except for the entry block, which needs some other initial
|  values. I've written something like this:
|  
|  cmmCopyPropagation dflags graph = do
|      let entry_blk = g_entry graph
|      g' <- dataflowPassFwd graph [(entry_blk, (Top , Top))] $
|              analRewFwd cpLattice cpTransfer cpRewrite
|      return . fst $ g'
|  
|  cpLattice = DataflowLattice "copy propagation" (Bottom, Bottom) cpJoin
|  
|  However, it seems that Bottom values passed to cpLattice are ignored - I could
|  replace them with `undefined` and the code would still run without causing an
|  error. Is there something obviously wrong in the way I pass initial fact values to
|  dataflowPassFwd, or should I look for the problem in other parts of my code?
|  
|  Janek
|  
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