Vectorise Case on products

3 files changed, 84 insertions, 3 deletions

diff --git a/compiler/vectorise/VectCore.hs b/compiler/vectorise/VectCore.hs
index 1ccc3813ce..de832793f6 100644
--- a/compiler/vectorise/VectCore.hs
+++ b/compiler/vectorise/VectCore.hs
@@ -7,13 +7,17 @@ module VectCore (
   vNonRec, vRec,
 
   vVar, vType, vNote, vLet,
-  vLams, vLamsWithoutLC, vVarApps
+  vLams, vLamsWithoutLC, vVarApps,
+  vCaseDEFAULT, vCaseProd
 ) where
 
 #include "HsVersions.h"
 
 import CoreSyn
+import CoreUtils      ( exprType )
+import DataCon        ( DataCon )
 import Type           ( Type )
+import Id             ( mkWildId )
 import Var
 
 type Vect a = (a,a)
@@ -69,4 +73,20 @@ vVarApps lc (ve, le) vvs = (ve `mkVarApps` vs, le `mkVarApps` (lc : ls))
   where
     (vs,ls) = unzip vvs 
 
-
+vCaseDEFAULT :: VExpr -> VVar -> Type -> Type -> VExpr -> VExpr
+vCaseDEFAULT (vscrut, lscrut) (vbndr, lbndr) vty lty (vbody, lbody)
+  = (Case vscrut vbndr vty (mkDEFAULT vbody),
+     Case lscrut lbndr lty (mkDEFAULT lbody))
+  where
+    mkDEFAULT e = [(DEFAULT, [], e)]
+
+vCaseProd :: VExpr -> Type -> Type
+          -> DataCon -> DataCon -> [Var] -> [VVar] -> VExpr -> VExpr
+vCaseProd (vscrut, lscrut) vty lty vdc ldc sh_bndrs bndrs
+          (vbody,lbody)
+  = (Case vscrut (mkWildId $ exprType vscrut) vty
+          [(DataAlt vdc, vbndrs, vbody)],
+     Case lscrut (mkWildId $ exprType lscrut) lty
+          [(DataAlt ldc, sh_bndrs ++ lbndrs, lbody)])
+  where
+    (vbndrs, lbndrs) = unzip bndrs
diff --git a/compiler/vectorise/VectUtils.hs b/compiler/vectorise/VectUtils.hs
index eec57d7538..46766ea8d1 100644
--- a/compiler/vectorise/VectUtils.hs
+++ b/compiler/vectorise/VectUtils.hs
@@ -4,7 +4,7 @@ module VectUtils (
   mkDataConTag,
   splitClosureTy,
   mkPADictType, mkPArrayType,
-  parrayReprTyCon, parrayReprDataCon,
+  parrayReprTyCon, parrayReprDataCon, mkVScrut,
   paDictArgType, paDictOfType, paDFunType,
   paMethod, lengthPA, replicatePA, emptyPA, liftPA,
   polyAbstract, polyApply, polyVApply,
@@ -120,6 +120,12 @@ parrayReprDataCon ty
       let [dc] = tyConDataCons tc
       return (dc, arg_tys)
 
+mkVScrut :: VExpr -> VM (VExpr, TyCon, [Type])
+mkVScrut (ve, le)
+  = do
+      (tc, arg_tys) <- parrayReprTyCon (exprType ve)
+      return ((ve, unwrapFamInstScrut tc arg_tys le), tc, arg_tys)
+
 paDictArgType :: TyVar -> VM (Maybe Type)
 paDictArgType tv = go (TyVarTy tv) (tyVarKind tv)
   where
diff --git a/compiler/vectorise/Vectorise.hs b/compiler/vectorise/Vectorise.hs
index 06fc542212..03fa131ca9 100644
--- a/compiler/vectorise/Vectorise.hs
+++ b/compiler/vectorise/Vectorise.hs
@@ -154,6 +154,14 @@ vectBndrIn v p
       x <- p
       return (vv, x)
 
+vectBndrIn' :: Var -> (VVar -> VM a) -> VM (VVar, a)
+vectBndrIn' v p
+  = localV
+  $ do
+      vv <- vectBndr v
+      x  <- p vv
+      return (vv, x)
+
 vectBndrsIn :: [Var] -> VM a -> VM ([VVar], a)
 vectBndrsIn vs p
   = localV
@@ -227,6 +235,12 @@ vectExpr (_, AnnApp fn arg)
       arg' <- vectExpr arg
       mkClosureApp fn' arg'
 
+vectExpr (_, AnnCase scrut bndr ty alts)
+  | isAlgType scrut_ty
+  = vectAlgCase scrut bndr ty alts
+  where
+    scrut_ty = exprType (deAnnotate scrut)
+
 vectExpr (_, AnnCase expr bndr ty alts)
   = panic "vectExpr: case"
 
@@ -279,3 +293,44 @@ vectTyAppExpr :: CoreExprWithFVs -> [Type] -> VM VExpr
 vectTyAppExpr (_, AnnVar v) tys = vectPolyVar v tys
 vectTyAppExpr e tys = pprPanic "vectTyAppExpr" (ppr $ deAnnotate e)
 
+type CoreAltWithFVs = AnnAlt Id VarSet
+
+-- We convert
+--
+--   case e :: t of v { ... }
+--
+-- to
+--
+--   V:    let v = e in case v of _ { ... }
+--   L:    let v = e in case v `cast` ... of _ { ... }
+--
+-- When lifting, we have to do it this way because v must have the type
+-- [:V(T):] but the scrutinee must be cast to the representation type.
+--   
+
+-- FIXME: this is too lazy
+vectAlgCase scrut bndr ty [(DEFAULT, [], body)]
+  = do
+      vscrut <- vectExpr scrut
+      vty    <- vectType ty
+      lty    <- mkPArrayType vty
+      (vbndr, vbody) <- vectBndrIn bndr (vectExpr body)
+      return $ vCaseDEFAULT vscrut vbndr vty lty vbody
+
+vectAlgCase scrut bndr ty [(DataAlt dc, bndrs, body)]
+  = do
+      vty <- vectType ty
+      lty <- mkPArrayType vty
+      vexpr <- vectExpr scrut
+      (vbndr, (vbndrs, vbody)) <- vectBndrIn bndr
+                                . vectBndrsIn bndrs
+                                $ vectExpr body
+
+      (vscrut, arr_tc, arg_tys) <- mkVScrut (vVar vbndr)
+      vect_dc <- maybeV (lookupDataCon dc)
+      let [arr_dc] = tyConDataCons arr_tc
+      let shape_tys = take (dataConRepArity arr_dc - length bndrs)
+                           (dataConRepArgTys arr_dc)
+      shape_bndrs <- mapM (newLocalVar FSLIT("s")) shape_tys
+      return . vLet (vNonRec vbndr vexpr)
+             $ vCaseProd vscrut vty lty vect_dc arr_dc shape_bndrs vbndrs vbody