X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fcmm%2FOptimizationFuel.hs;h=175dcd09b18a4c602cb9531796d0f4b7abf89673;hb=7fc01c4671980ea3c66d549c0ece4d82fd3f5ade;hp=7ec9d488554c603870de9b52c788f53d5fd80c5c;hpb=25628e2771424cae1b3366322e8ce6f8a85440f9;p=ghc-hetmet.git

diff --git a/compiler/cmm/OptimizationFuel.hs b/compiler/cmm/OptimizationFuel.hs
index 7ec9d48..175dcd0 100644
--- a/compiler/cmm/OptimizationFuel.hs
+++ b/compiler/cmm/OptimizationFuel.hs
@@ -1,30 +1,29 @@
+-- | Optimisation fuel is used to control the amount of work the optimiser does.
+--
+-- Every optimisation step consumes a certain amount of fuel and stops when
+-- it runs out of fuel.  This can be used e.g. to debug optimiser bugs: Run
+-- the optimiser with varying amount of fuel to find out the exact number of
+-- steps where a bug is introduced in the output.
 module OptimizationFuel
-    ( OptimizationFuel ,  canRewriteWithFuel, maybeRewriteWithFuel, oneLessFuel
+    ( OptimizationFuel,  canRewriteWithFuel, maybeRewriteWithFuel, oneLessFuel
     , OptFuelState, initOptFuelState --, setTotalFuel
     , tankFilledTo, diffFuel
     , FuelConsumer
     , FuelUsingMonad, FuelState
     , lastFuelPass, fuelExhausted, fuelRemaining, fuelDecrement, fuelDec1
-    --, lastFuelPassInState , fuelExhaustedInState, fuelRemainingInState
-    --, fuelDecrementState
-    --, runFuel
-    , runFuelIO
-    --, runFuelWithLastPass
-    , fuelConsumingPass
+    , runFuelIO, fuelConsumingPass
     , FuelMonad
     , liftUniq
     , lGraphOfGraph -- needs to be able to create a unique ID...
     )
 where
 
-import StackSlot
+import BlockId
 import ZipCfg
-
 --import GHC.Exts (State#)
 import Panic
-
 import Data.IORef
-import Monad
+import Control.Monad
 import StaticFlags (opt_Fuel)
 import UniqSupply
 
@@ -66,7 +65,7 @@ diffFuel (OptimizationFuel f) (OptimizationFuel f') = f - f'
 -- type OptimizationFuel = State# () -- would like this, but it won't work
 data OptimizationFuel = OptimizationFuel
   deriving Show
-tankFilledTo _ = undefined -- should be impossible to evaluate
+tankFilledTo _ = panic "tankFilledTo" -- should be impossible to evaluate
   -- realWorld# might come in handy, too...
 canRewriteWithFuel OptimizationFuel = True
 maybeRewriteWithFuel _ ma = ma
@@ -139,28 +138,3 @@ lGraphOfGraph :: Graph m l -> FuelMonad (LGraph m l)
 lGraphOfGraph (Graph tail blocks) =
   do entry <- liftM BlockId $ getUniqueM
      return $ LGraph entry (insertBlock (Block entry tail) blocks)
-
-
--- JD: I'm not sure what NR's plans are for the following code.
--- Perhaps these functions will be useful in the future, or perhaps I've made
--- them obsoltete.
-
---initialFuelState :: OptimizationFuel -> FuelState
---initialFuelState fuel = FuelState fuel "unoptimized program"
---runFuel             :: FuelMonad a -> FuelConsumer a
---runFuelWithLastPass :: FuelMonad a -> FuelConsumer (a, String)
-
---runFuel             (FuelMonad f) fuel = let (a, s) = f $ initialFuelState fuel
---                                         in (a, fs_fuellimit s)
---runFuelWithLastPass (FuelMonad f) fuel = let (a, s) = f $ initialFuelState fuel
---                                         in ((a, fs_lastpass s), fs_fuellimit s)
-
--- lastFuelPassInState :: FuelState -> String
--- lastFuelPassInState = fs_lastpass
-
--- fuelExhaustedInState :: FuelState -> Bool
--- fuelExhaustedInState = canRewriteWithFuel . fs_fuellimit
-
--- fuelRemainingInState :: FuelState -> OptimizationFuel
--- fuelRemainingInState = fs_fuellimit
-