From: simonpj@microsoft.com <unknown>
Date: Tue, 15 Feb 2011 14:36:55 +0000 (+0000)
Subject: Ensure exprIsCheap/exprIsExpandable deal with Cast properly
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=c406b5bde899dd2b28e5239937c909d675bca356

Ensure exprIsCheap/exprIsExpandable deal with Cast properly

This bug was causing a Lint error on the stable branch. For some
reason it doesn't show up in HEAD, but it's still worth fixing.

The point is that ((f `cast` co) a) is cheap if f has arity>1.
This was being gratuitously missed before.
---

diff --git a/compiler/coreSyn/CoreUtils.lhs b/compiler/coreSyn/CoreUtils.lhs
index b50cb01..c901fc2 100644
--- a/compiler/coreSyn/CoreUtils.lhs
+++ b/compiler/coreSyn/CoreUtils.lhs
@@ -563,6 +563,7 @@ exprIsCheap' good_app other_expr 	-- Applications and variables
   = go other_expr []
   where
 	-- Accumulate value arguments, then decide
+    go (Cast e _) val_args                 = go e val_args
     go (App f a) val_args | isRuntimeArg a = go f (a:val_args)
 			  | otherwise      = go f val_args