Add literal-shift rewrite rules

[ghc-hetmet.git] / compiler / prelude / PrelRules.lhs

diff --git a/compiler/prelude/PrelRules.lhs b/compiler/prelude/PrelRules.lhs
index 8604647..0775670 100644 (file)
--- a/compiler/prelude/PrelRules.lhs
+++ b/compiler/prelude/PrelRules.lhs
@@ -45,7 +45,7 @@ import Outputable
 import FastString
 import StaticFlags      ( opt_SimplExcessPrecision )
 
-import Data.Bits       ( Bits(..) )
+import Data.Bits as Bits       ( Bits(..) )
 #if __GLASGOW_HASKELL__ >= 500
 import Data.Word       ( Word )
 #else
@@ -98,6 +98,9 @@ primOpRules op op_name = primop_rule op
     primop_rule IntQuotOp   = two_lits (intOp2Z    quot)
     primop_rule IntRemOp    = two_lits (intOp2Z    rem)
     primop_rule IntNegOp    = one_lit  negOp
+    primop_rule ISllOp      = two_lits (intShiftOp2 Bits.shiftL)
+    primop_rule ISraOp      = two_lits (intShiftOp2 Bits.shiftR)
+    primop_rule ISrlOp      = two_lits (intShiftOp2 shiftRightLogical)
 
        -- Word operations
 #if __GLASGOW_HASKELL__ >= 500
@@ -112,6 +115,8 @@ primOpRules op op_name = primop_rule op
     primop_rule OrOp        = two_lits (wordBitOp2 (.|.))
     primop_rule XorOp       = two_lits (wordBitOp2 xor)
 #endif
+    primop_rule SllOp       = two_lits (wordShiftOp2 Bits.shiftL)
+    primop_rule SrlOp       = two_lits (wordShiftOp2 shiftRightLogical)
 
        -- coercions
     primop_rule Word2IntOp     = one_lit (litCoerce word2IntLit)
@@ -223,42 +228,67 @@ cmpOp cmp l1 l2
 
 --------------------------
 
-negOp (MachFloat 0.0) = Nothing  -- can't represent -0.0 as a Rational
-negOp (MachFloat f)   = Just (mkFloatVal (-f))
+negOp :: Literal -> Maybe CoreExpr     -- Negate
+negOp (MachFloat 0.0)  = Nothing  -- can't represent -0.0 as a Rational
+negOp (MachFloat f)    = Just (mkFloatVal (-f))
 negOp (MachDouble 0.0) = Nothing
 negOp (MachDouble d)   = Just (mkDoubleVal (-d))
 negOp (MachInt i)      = intResult (-i)
 negOp l                       = Nothing
 
 --------------------------
+intOp2 :: (Integer->Integer->Integer) -> Literal -> Literal -> Maybe CoreExpr
 intOp2 op (MachInt i1) (MachInt i2) = intResult (i1 `op` i2)
 intOp2 op l1          l2           = Nothing           -- Could find LitLit
 
+intOp2Z :: (Integer->Integer->Integer) -> Literal -> Literal -> Maybe CoreExpr
+-- Like intOp2, but Nothing if i2=0
 intOp2Z op (MachInt i1) (MachInt i2)
-  | i2 /= 0 = Just (mkIntVal (i1 `op` i2))
+  | i2 /= 0 = intResult (i1 `op` i2)
 intOp2Z op l1 l2 = Nothing             -- LitLit or zero dividend
 
+intShiftOp2 :: (Integer->Int->Integer) -> Literal -> Literal -> Maybe CoreExpr
+       -- Shifts take an Int; hence second arg of op is Int
+intShiftOp2 op (MachInt i1) (MachInt i2) = intResult (i1 `op` fromInteger i2)
+intShiftOp2 op l1           l2           = Nothing 
+
+shiftRightLogical :: Integer -> Int -> Integer
+-- Shift right, putting zeros in rather than sign-propagating as Bits.shiftR would do
+-- Do this by converting to Word and back.  Obviously this won't work for big 
+-- values, but its ok as we use it here
+shiftRightLogical x n = fromIntegral (fromInteger x `shiftR` n :: Word)
+
+
 --------------------------
 #if __GLASGOW_HASKELL__ >= 500
+wordOp2 :: (Integer->Integer->Integer) -> Literal -> Literal -> Maybe CoreExpr
 wordOp2 op (MachWord w1) (MachWord w2)
   = wordResult (w1 `op` w2)
 wordOp2 op l1 l2 = Nothing             -- Could find LitLit
 #endif
 
+wordOp2Z :: (Integer->Integer->Integer) -> Literal -> Literal -> Maybe CoreExpr
 wordOp2Z op (MachWord w1) (MachWord w2)
-  | w2 /= 0 = Just (mkWordVal (w1 `op` w2))
+  | w2 /= 0 = wordResult (w1 `op` w2)
 wordOp2Z op l1 l2 = Nothing    -- LitLit or zero dividend
 
 #if __GLASGOW_HASKELL__ >= 500
 wordBitOp2 op l1@(MachWord w1) l2@(MachWord w2)
-  = Just (mkWordVal (w1 `op` w2))
+  = wordResult (w1 `op` w2)
 #else
 -- Integer is not an instance of Bits, so we operate on Word64
 wordBitOp2 op l1@(MachWord w1) l2@(MachWord w2)
-  = Just (mkWordVal ((fromIntegral::Word64->Integer) (fromIntegral w1 `op` fromIntegral w2)))
+  = wordResult ((fromIntegral::Word64->Integer) (fromIntegral w1 `op` fromIntegral w2))
 #endif
 wordBitOp2 op l1 l2 = Nothing          -- Could find LitLit
 
+wordShiftOp2 :: (Integer->Int->Integer) -> Literal -> Literal -> Maybe CoreExpr
+       -- Shifts take an Int; hence second arg of op is Int
+wordShiftOp2 op (MachWord x) (MachInt n) 
+  = wordResult (x `op` fromInteger n)
+       -- Do the shift at type Integer
+wordShiftOp2 op l1 l2 = Nothing        
+
 --------------------------
 floatOp2  op (MachFloat f1) (MachFloat f2)
   = Just (mkFloatVal (f1 `op` f2))