Remove -fkill-absence and -fkill-one-shot flagswip/dmdanal-remove-killUsage

They seem to be a benchmarking vestige of the Cardinality paper and
probably shouldn't have been merged to HEAD in the first place.

3 files changed, 3 insertions, 41 deletions

diff --git a/compiler/GHC/Core/Op/DmdAnal.hs b/compiler/GHC/Core/Op/DmdAnal.hs
index 57544519d3..eb9f277f8a 100644
--- a/compiler/GHC/Core/Op/DmdAnal.hs
+++ b/compiler/GHC/Core/Op/DmdAnal.hs
@@ -603,7 +603,7 @@ dmdAnalRhsLetDown rec_flag env let_dmd id rhs
     -- TODO: Won't the following line unnecessarily trim down arity for join
     --       points returning a lambda in a C(S) context?
     sig            = mkStrictSigForArity rhs_arity (mkDmdType sig_fv rhs_dmds rhs_div)
-    id'            = set_idStrictness env id sig
+    id'            = setIdStrictness id sig
         -- See Note [NOINLINE and strictness]
 
 
@@ -1171,8 +1171,7 @@ findBndrDmd :: AnalEnv -> Bool -> DmdType -> Id -> (DmdType, Demand)
 findBndrDmd env arg_of_dfun dmd_ty id
   = (dmd_ty', dmd')
   where
-    dmd' = killUsageDemand (ae_dflags env) $
-           strictify $
+    dmd' = strictify $
            trimToType starting_dmd (findTypeShape fam_envs id_ty)
 
     (dmd_ty', starting_dmd) = peelFV dmd_ty id
@@ -1191,10 +1190,6 @@ findBndrDmd env arg_of_dfun dmd_ty id
 
     fam_envs = ae_fam_envs env
 
-set_idStrictness :: AnalEnv -> Id -> StrictSig -> Id
-set_idStrictness env id sig
-  = setIdStrictness id (killUsageSig (ae_dflags env) sig)
-
 {- Note [Initialising strictness]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 See section 9.2 (Finding fixpoints) of the paper.
diff --git a/compiler/GHC/Driver/Session.hs b/compiler/GHC/Driver/Session.hs
index bdb8daebce..cf9b84dcf4 100644
--- a/compiler/GHC/Driver/Session.hs
+++ b/compiler/GHC/Driver/Session.hs
@@ -3568,8 +3568,6 @@ fFlagsDeps = [
   flagGhciSpec "implicit-import-qualified"    Opt_ImplicitImportQualified,
   flagSpec "irrefutable-tuples"               Opt_IrrefutableTuples,
   flagSpec "keep-going"                       Opt_KeepGoing,
-  flagSpec "kill-absence"                     Opt_KillAbsence,
-  flagSpec "kill-one-shot"                    Opt_KillOneShot,
   flagSpec "late-dmd-anal"                    Opt_LateDmdAnal,
   flagSpec "late-specialise"                  Opt_LateSpecialise,
   flagSpec "liberate-case"                    Opt_LiberateCase,
diff --git a/compiler/basicTypes/Demand.hs b/compiler/basicTypes/Demand.hs
index 196bedb8ee..28282d4382 100644
--- a/compiler/basicTypes/Demand.hs
+++ b/compiler/basicTypes/Demand.hs
@@ -50,7 +50,7 @@ module Demand (
         TypeShape(..), peelTsFuns, trimToType,
 
         useCount, isUsedOnce, reuseEnv,
-        killUsageDemand, killUsageSig, zapUsageDemand, zapUsageEnvSig,
+        zapUsageDemand, zapUsageEnvSig,
         zapUsedOnceDemand, zapUsedOnceSig,
         strictifyDictDmd, strictifyDmd
 
@@ -60,7 +60,6 @@ module Demand (
 
 import GhcPrelude
 
-import GHC.Driver.Session
 import Outputable
 import Var ( Var )
 import VarEnv
@@ -1754,14 +1753,6 @@ that it is going to diverge. This is the reason why we use the
 function appIsBottom, which, given a strictness signature and a number
 of arguments, says conservatively if the function is going to diverge
 or not.
-
-Zap absence or one-shot information, under control of flags
-
-Note [Killing usage information]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The flags -fkill-one-shot and -fkill-absence let you switch off the generation
-of absence or one-shot information altogether.  This is only used for performance
-tests, to see how important they are.
 -}
 
 zapUsageEnvSig :: StrictSig -> StrictSig
@@ -1790,34 +1781,12 @@ zapUsedOnceSig :: StrictSig -> StrictSig
 zapUsedOnceSig (StrictSig (DmdType env ds r))
     = StrictSig (DmdType env (map zapUsedOnceDemand ds) r)
 
-killUsageDemand :: DynFlags -> Demand -> Demand
--- See Note [Killing usage information]
-killUsageDemand dflags dmd
-  | Just kfs <- killFlags dflags = kill_usage kfs dmd
-  | otherwise                    = dmd
-
-killUsageSig :: DynFlags -> StrictSig -> StrictSig
--- See Note [Killing usage information]
-killUsageSig dflags sig@(StrictSig (DmdType env ds r))
-  | Just kfs <- killFlags dflags = StrictSig (DmdType env (map (kill_usage kfs) ds) r)
-  | otherwise                    = sig
-
 data KillFlags = KillFlags
     { kf_abs         :: Bool
     , kf_used_once   :: Bool
     , kf_called_once :: Bool
     }
 
-killFlags :: DynFlags -> Maybe KillFlags
--- See Note [Killing usage information]
-killFlags dflags
-  | not kf_abs && not kf_used_once = Nothing
-  | otherwise                      = Just (KillFlags {..})
-  where
-    kf_abs         = gopt Opt_KillAbsence dflags
-    kf_used_once   = gopt Opt_KillOneShot dflags
-    kf_called_once = kf_used_once
-
 kill_usage :: KillFlags -> Demand -> Demand
 kill_usage kfs (JD {sd = s, ud = u}) = JD {sd = s, ud = zap_musg kfs u}