``Long-distance'' floating of bindings towards the top level.
\begin{code}
-module FloatOut ( floatOutwards ) where
+{-# 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
-#include "HsVersions.h"
+module FloatOut ( floatOutwards ) where
import CoreSyn
-import CoreUtils ( mkSCC, exprIsHNF, exprIsTrivial )
+import CoreUtils
import DynFlags ( DynFlags, DynFlag(..), FloatOutSwitches(..) )
import ErrUtils ( dumpIfSet_dyn )
import UniqSupply ( UniqSupply )
import List ( partition )
import Outputable
+import FastString
\end{code}
-----------------
let { (tlets, ntlets, lams) = get_stats (sum_stats fss) };
dumpIfSet_dyn dflags Opt_D_dump_simpl_stats "FloatOut stats:"
- (hcat [ int tlets, ptext SLIT(" Lets floated to top level; "),
- int ntlets, ptext SLIT(" Lets floated elsewhere; from "),
- int lams, ptext SLIT(" Lambda groups")]);
+ (hcat [ int tlets, ptext (sLit " Lets floated to top level; "),
+ int ntlets, ptext (sLit " Lets floated elsewhere; from "),
+ int lams, ptext (sLit " Lambda groups")]);
endPass dflags float_msg Opt_D_verbose_core2core (concat binds_s')
{- no specific flag for dumping float-out -}
floatRhs lvl arg -- Used for nested non-rec rhss, and fn args
-- See Note [Floating out of RHS]
= case (floatExpr lvl arg) of { (fsa, floats, arg') ->
- if exprIsHNF arg' || exprIsTrivial arg' then
+ if exprIsCheap arg' then
(fsa, floats, arg')
else
case (partitionByMajorLevel lvl floats) of { (floats', heres) ->
-- bindings just after the '='. And some of them might (correctly)
-- be strict even though the 'let f' is lazy, because f, being a value,
-- gets its demand-info zapped by the simplifier.
+--
+-- We use exprIsCheap because that is also what's used by the simplifier
+-- to decide whether to float a let out of a let
floatExpr _ (Var v) = (zeroStats, [], Var v)
floatExpr _ (Type ty) = (zeroStats, [], Type ty)
= Rec [(binder, mkSCC dupd_cc rhs) | (binder, rhs) <- pairs]
floatExpr lvl (Note InlineMe expr) -- Other than SCCs
- = case floatExpr InlineCtxt expr of { (fs, floating_defns, expr') ->
- -- There can be some floating_defns, arising from
- -- ordinary lets that were there all the time. It seems
- -- more efficient to test once here than to avoid putting
- -- them into floating_defns (which would mean testing for
- -- inlineCtxt at every let)
- (fs, [], Note InlineMe (install floating_defns expr')) } -- See notes in SetLevels
+ = (zeroStats, [], Note InlineMe (unTag expr))
+ -- Do no floating at all inside INLINE. [_$_]
+ -- The SetLevels pass did not clone the bindings, so it's
+ -- unsafe to do any floating, even if we dump the results
+ -- inside the Note (which is what we used to do).
floatExpr lvl (Note note expr) -- Other than SCCs
= case (floatExpr lvl expr) of { (fs, floating_defns, expr') ->
floatList f (a:as) = case f a of { (fs_a, binds_a, b) ->
case floatList f as of { (fs_as, binds_as, bs) ->
(fs_a `add_stats` fs_as, binds_a ++ binds_as, b:bs) }}
+
+unTagBndr :: TaggedBndr tag -> CoreBndr
+unTagBndr (TB b _) = b
+
+unTag :: TaggedExpr tag -> CoreExpr
+unTag (Var v) = Var v
+unTag (Lit l) = Lit l
+unTag (Type ty) = Type ty
+unTag (Note n e) = Note n (unTag e)
+unTag (App e1 e2) = App (unTag e1) (unTag e2)
+unTag (Lam b e) = Lam (unTagBndr b) (unTag e)
+unTag (Cast e co) = Cast (unTag e) co
+unTag (Let (Rec prs) e) = Let (Rec [(unTagBndr b,unTag r) | (b, r) <- prs]) (unTag e)
+unTag (Let (NonRec b r) e) = Let (NonRec (unTagBndr b) (unTag r)) (unTag e)
+unTag (Case e b ty alts) = Case (unTag e) (unTagBndr b) ty
+ [(c, map unTagBndr bs, unTag r) | (c,bs,r) <- alts]
\end{code}
%************************************************************************