{-# OPTIONS -optc-DNON_POSIX_SOURCE #-}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
module PrelRules ( primOpRules, builtinRules ) where
#include "HsVersions.h"
, narrow8WordLit, narrow16WordLit, narrow32WordLit
, char2IntLit, int2CharLit
, float2IntLit, int2FloatLit, double2IntLit, int2DoubleLit
- , float2DoubleLit, double2FloatLit
+ , float2DoubleLit, double2FloatLit, litFitsInChar
)
import PrimOp ( PrimOp(..), tagToEnumKey )
import TysWiredIn ( boolTy, trueDataConId, falseDataConId )
import Outputable
import FastString
import StaticFlags ( opt_SimplExcessPrecision )
-
-import Data.Bits as Bits ( Bits(..), shiftL, shiftR )
- -- shiftL and shiftR were not always methods of Bits
+import Data.Bits as Bits
import Data.Word ( Word )
\end{code}
primop_rule Narrow16WordOp = one_lit (litCoerce narrow16WordLit)
primop_rule Narrow32WordOp = one_lit (litCoerce narrow32WordLit)
primop_rule OrdOp = one_lit (litCoerce char2IntLit)
- primop_rule ChrOp = one_lit (litCoerce int2CharLit)
+ primop_rule ChrOp = one_lit (predLitCoerce litFitsInChar int2CharLit)
primop_rule Float2IntOp = one_lit (litCoerce float2IntLit)
primop_rule Int2FloatOp = one_lit (litCoerce int2FloatLit)
primop_rule Double2IntOp = one_lit (litCoerce double2IntLit)
litCoerce :: (Literal -> Literal) -> Literal -> Maybe CoreExpr
litCoerce fn lit = Just (Lit (fn lit))
+predLitCoerce :: (Literal -> Bool) -> (Literal -> Literal) -> Literal -> Maybe CoreExpr
+predLitCoerce p fn lit
+ | p lit = Just (Lit (fn lit))
+ | otherwise = Nothing
+
--------------------------
cmpOp :: (Ordering -> Bool) -> Literal -> Literal -> Maybe CoreExpr
cmpOp cmp l1 l2
%* *
%************************************************************************
+Note [Scoping for Builtin rules]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+When compiling a (base-package) module that defines one of the
+functions mentioned in the RHS of a built-in rule, there's a danger
+that we'll see
+
+ f = ...(eq String x)....
+
+ ....and lower down...
+
+ eqString = ...
+
+Then a rewrite would give
+
+ f = ...(eqString x)...
+ ....and lower down...
+ eqString = ...
+
+and lo, eqString is not in scope. This only really matters when we get to code
+generation. With -O we do a GlomBinds step that does a new SCC analysis on the whole
+set of bindings, which sorts out the dependency. Without -O we don't do any rule
+rewriting so again we are fine.
+
+(This whole thing doesn't show up for non-built-in rules because their dependencies
+are explicit.)
+
+
\begin{code}
builtinRules :: [CoreRule]
-- Rules for non-primops that can't be expressed using a RULE pragma