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

4 files changed, 8 insertions, 7 deletions

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