X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FdeSugar%2FDsExpr.lhs;h=b823437e27349f1b917613d6f3e7930cde7b3e5d;hb=51873bdac451ee4a7e4b2ebc26a8706c08eab8e1;hp=0633717d09538b9f0f1077a42729eb7efa4e3731;hpb=6febb616f1ff46942434e9df39c6e4977b07cc6f;p=ghc-hetmet.git

diff --git a/compiler/deSugar/DsExpr.lhs b/compiler/deSugar/DsExpr.lhs
index 0633717..b823437 100644
--- a/compiler/deSugar/DsExpr.lhs
+++ b/compiler/deSugar/DsExpr.lhs
@@ -505,10 +505,8 @@ dsExpr (HsBinTick ixT ixF e) = do
 
 \begin{code}
 
-#ifdef DEBUG
 -- HsSyn constructs that just shouldn't be here:
 dsExpr (ExprWithTySig _ _)  = panic "dsExpr:ExprWithTySig"
-#endif
 
 
 findField :: [HsRecField Id arg] -> Name -> [arg]
@@ -541,13 +539,18 @@ fruitless allocations.  Essentially, whenever we see a list literal
    
    If fusion fails to occur then build will get inlined and (since we
    defined a RULE for foldr (:) []) we will get back exactly the
-   normal desugaring for an explicit list! However, if it does occur
-   then we can potentially save quite a bit of allocation (up to 25\%
-   of the total in some nofib programs!)
+   normal desugaring for an explicit list.
+
+This optimisation can be worth a lot: up to 25% of the total
+allocation in some nofib programs. Specifically
+
+        Program           Size    Allocs   Runtime  CompTime
+        rewrite          +0.0%    -26.3%      0.02     -1.8%
+           ansi          -0.3%    -13.8%      0.00     +0.0%
+           lift          +0.0%     -8.7%      0.00     -2.3%
 
 Of course, if rules aren't turned on then there is pretty much no
 point doing this fancy stuff, and it may even be harmful.
-
 \begin{code}
 
 dsExplicitList :: PostTcType -> [LHsExpr Id] -> DsM CoreExpr