Make vectInfoParallelVars a DVarSet

We dump it in the interface file, so we need to do it in a
deterministic order. I haven't seen any problems with this
during my testing, but that's probably because it's unused.

Test Plan: ./validate

Reviewers: simonmar, austin, bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2313

GHC Trac Issues: #4012

8 files changed, 19 insertions, 17 deletions

diff --git a/compiler/iface/MkIface.hs b/compiler/iface/MkIface.hs
index 67bbd9505b..fcf63af369 100644
--- a/compiler/iface/MkIface.hs
+++ b/compiler/iface/MkIface.hs
@@ -327,7 +327,7 @@ mkIface_ hsc_env maybe_old_fingerprint
        { ifaceVectInfoVar            = [Var.varName v | (v, _  ) <- varEnvElts  vVar]
        , ifaceVectInfoTyCon          = [tyConName t   | (t, t_v) <- nameEnvElts vTyCon, t /= t_v]
        , ifaceVectInfoTyConReuse     = [tyConName t   | (t, t_v) <- nameEnvElts vTyCon, t == t_v]
-       , ifaceVectInfoParallelVars   = [Var.varName v | v <- varSetElems vParallelVars]
+       , ifaceVectInfoParallelVars   = [Var.varName v | v <- dVarSetElems vParallelVars]
        , ifaceVectInfoParallelTyCons = nameSetElemsStable vParallelTyCons
        }
 
diff --git a/compiler/iface/TcIface.hs b/compiler/iface/TcIface.hs
index 694bbd7c92..320594ca74 100644
--- a/compiler/iface/TcIface.hs
+++ b/compiler/iface/TcIface.hs
@@ -779,7 +779,7 @@ tcIfaceVectInfo mod typeEnv (IfaceVectInfo
                   { vectInfoVar            = mkVarEnv  vVars `extendVarEnvList` concat vScSels
                   , vectInfoTyCon          = mkNameEnv vTyCons
                   , vectInfoDataCon        = mkNameEnv (concat vDataCons)
-                  , vectInfoParallelVars   = mkVarSet  vParallelVars
+                  , vectInfoParallelVars   = mkDVarSet vParallelVars
                   , vectInfoParallelTyCons = parallelTyConsSet
                   }
        }
diff --git a/compiler/main/HscTypes.hs b/compiler/main/HscTypes.hs
index 79e5f694cf..a5eee7c5d8 100644
--- a/compiler/main/HscTypes.hs
+++ b/compiler/main/HscTypes.hs
@@ -2642,7 +2642,7 @@ data VectInfo
     { vectInfoVar            :: VarEnv  (Var    , Var  )    -- ^ @(f, f_v)@ keyed on @f@
     , vectInfoTyCon          :: NameEnv (TyCon  , TyCon)    -- ^ @(T, T_v)@ keyed on @T@
     , vectInfoDataCon        :: NameEnv (DataCon, DataCon)  -- ^ @(C, C_v)@ keyed on @C@
-    , vectInfoParallelVars   :: VarSet                      -- ^ set of parallel variables
+    , vectInfoParallelVars   :: DVarSet                     -- ^ set of parallel variables
     , vectInfoParallelTyCons :: NameSet                     -- ^ set of parallel type constructors
     }
 
@@ -2673,14 +2673,14 @@ data IfaceVectInfo
 
 noVectInfo :: VectInfo
 noVectInfo
-  = VectInfo emptyVarEnv emptyNameEnv emptyNameEnv emptyVarSet emptyNameSet
+  = VectInfo emptyVarEnv emptyNameEnv emptyNameEnv emptyDVarSet emptyNameSet
 
 plusVectInfo :: VectInfo -> VectInfo -> VectInfo
 plusVectInfo vi1 vi2 =
   VectInfo (vectInfoVar            vi1 `plusVarEnv`    vectInfoVar            vi2)
            (vectInfoTyCon          vi1 `plusNameEnv`   vectInfoTyCon          vi2)
            (vectInfoDataCon        vi1 `plusNameEnv`   vectInfoDataCon        vi2)
-           (vectInfoParallelVars   vi1 `unionVarSet`   vectInfoParallelVars   vi2)
+           (vectInfoParallelVars   vi1 `unionDVarSet`  vectInfoParallelVars   vi2)
            (vectInfoParallelTyCons vi1 `unionNameSet` vectInfoParallelTyCons vi2)
 
 concatVectInfo :: [VectInfo] -> VectInfo
diff --git a/compiler/main/TidyPgm.hs b/compiler/main/TidyPgm.hs
index 401f939d44..daf3d00584 100644
--- a/compiler/main/TidyPgm.hs
+++ b/compiler/main/TidyPgm.hs
@@ -493,11 +493,12 @@ tidyVectInfo (_, var_env) info@(VectInfo { vectInfoVar          = vars
                          , isDataConWorkId var || not (isImplicitId var)
                          ]
 
-    tidy_parallelVars = mkVarSet [ tidy_var
-                                 | var <- varSetElems parallelVars
-                                 , let tidy_var = lookup_var var
-                                 , isExternalId tidy_var && isExportedId tidy_var
-                                 ]
+    tidy_parallelVars = mkDVarSet
+                          [ tidy_var
+                          | var <- dVarSetElems parallelVars
+                          , let tidy_var = lookup_var var
+                          , isExternalId tidy_var && isExportedId tidy_var
+                          ]
 
     lookup_var var = lookupWithDefaultVarEnv var_env var var
 
diff --git a/compiler/vectorise/Vectorise/Env.hs b/compiler/vectorise/Vectorise/Env.hs
index c3b0ee1b02..e4ab79eed7 100644
--- a/compiler/vectorise/Vectorise/Env.hs
+++ b/compiler/vectorise/Vectorise/Env.hs
@@ -30,6 +30,7 @@ import NameSet
 import Name
 import NameEnv
 import FastString
+import UniqDFM
 
 
 import Data.Maybe
@@ -86,7 +87,7 @@ data GlobalEnv
           -- ^Mapping from global variables to their vectorised versions — aka the /vectorisation
           -- map/.
 
-        , global_parallel_vars        :: VarSet
+        , global_parallel_vars        :: DVarSet
           -- ^The domain of 'global_vars'.
           --
           -- This information is not redundant as it is impossible to extract the domain from a
@@ -208,8 +209,8 @@ modVectInfo env mg_ids mg_tyCons vectDecls info
     { vectInfoVar            = mk_env ids      (global_vars     env)
     , vectInfoTyCon          = mk_env tyCons   (global_tycons   env)
     , vectInfoDataCon        = mk_env dataCons (global_datacons env)
-    , vectInfoParallelVars   = (global_parallel_vars   env `minusVarSet`  vectInfoParallelVars   info)
-                               `intersectVarSet` (mkVarSet ids)
+    , vectInfoParallelVars   = (global_parallel_vars   env `minusDVarSet`  vectInfoParallelVars   info)
+                               `udfmIntersectUFM` (mkVarSet ids)
     , vectInfoParallelTyCons =  global_parallel_tycons env `minusNameSet` vectInfoParallelTyCons info
     }
   where
diff --git a/compiler/vectorise/Vectorise/Exp.hs b/compiler/vectorise/Vectorise/Exp.hs
index 368d99a1e3..770adb77de 100644
--- a/compiler/vectorise/Vectorise/Exp.hs
+++ b/compiler/vectorise/Vectorise/Exp.hs
@@ -1039,13 +1039,13 @@ vectAvoidInfo :: VarSet -> CoreExprWithFVs -> VM CoreExprWithVectInfo
 vectAvoidInfo pvs ce@(_, AnnVar v)
   = do
     { gpvs <- globalParallelVars
-    ; vi <- if v `elemVarSet` pvs || v `elemVarSet` gpvs
+    ; vi <- if v `elemVarSet` pvs || v `elemDVarSet` gpvs
             then return VIParr
             else vectAvoidInfoTypeOf ce
     ; viTrace ce vi []
     ; when (vi == VIParr) $
         traceVt "  reason:" $ if v `elemVarSet` pvs  then text "local"  else
-                              if v `elemVarSet` gpvs then text "global" else text "parallel type"
+                              if v `elemDVarSet` gpvs then text "global" else text "parallel type"
 
     ; return ((fvs, vi), AnnVar v)
     }
diff --git a/compiler/vectorise/Vectorise/Monad.hs b/compiler/vectorise/Vectorise/Monad.hs
index 4e7ee168b7..7c04dfe0b1 100644
--- a/compiler/vectorise/Vectorise/Monad.hs
+++ b/compiler/vectorise/Vectorise/Monad.hs
@@ -185,7 +185,7 @@ dumpVar dflags var
 addGlobalParallelVar :: Var -> VM ()
 addGlobalParallelVar var
   = do { traceVt "addGlobalParallelVar" (ppr var)
-       ; updGEnv $ \env -> env{global_parallel_vars = extendVarSet (global_parallel_vars env) var}
+       ; updGEnv $ \env -> env{global_parallel_vars = extendDVarSet (global_parallel_vars env) var}
        }
 
 -- |Mark the given type constructor as parallel — i.e., its values might embed parallel arrays.
diff --git a/compiler/vectorise/Vectorise/Monad/Global.hs b/compiler/vectorise/Vectorise/Monad/Global.hs
index 0d3e0c0c91..cd642f37b6 100644
--- a/compiler/vectorise/Vectorise/Monad/Global.hs
+++ b/compiler/vectorise/Vectorise/Monad/Global.hs
@@ -135,7 +135,7 @@ lookupVectDecl var
 
 -- |Get the set of global parallel variables.
 --
-globalParallelVars :: VM VarSet
+globalParallelVars :: VM DVarSet
 globalParallelVars = readGEnv global_parallel_vars
 
 -- |Get the set of all parallel type constructors (those that may embed parallelism) including both