X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Fcmm%2FOptimizationFuel.hs;h=175dcd09b18a4c602cb9531796d0f4b7abf89673;hp=5e400c4009f14916d7318a485a2840685cf11fcc;hb=8a9eb3cd35117c62ac9758d118c6f4109b7330cb;hpb=31a9d04804d9cacda35695c5397590516b964964

diff --git a/compiler/cmm/OptimizationFuel.hs b/compiler/cmm/OptimizationFuel.hs
index 5e400c4..175dcd0 100644
--- a/compiler/cmm/OptimizationFuel.hs
+++ b/compiler/cmm/OptimizationFuel.hs
@@ -1,3 +1,9 @@
+-- | 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
     , OptFuelState, initOptFuelState --, setTotalFuel
@@ -17,7 +23,7 @@ import ZipCfg
 --import GHC.Exts (State#)
 import Panic
 import Data.IORef
-import Monad
+import Control.Monad
 import StaticFlags (opt_Fuel)
 import UniqSupply