From: Ian Lynagh <igloo@earth.li>
Date: Wed, 22 Aug 2007 14:34:22 +0000 (+0000)
Subject: Use unsafeDupableInterleaveIO in UniqSupply
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=19b0b165a24606dbdb1f4dd7728da7346845a5a0

Use unsafeDupableInterleaveIO in UniqSupply
We'll need to change this if we ever use threads in GHC, but for now it
drops mkSplitUniqSupply from 35% time down below 0.1% when compiling
J.hs from #1136.
---

diff --git a/compiler/basicTypes/UniqSupply.lhs b/compiler/basicTypes/UniqSupply.lhs
index 8dcf595..8e3ac96 100644
--- a/compiler/basicTypes/UniqSupply.lhs
+++ b/compiler/basicTypes/UniqSupply.lhs
@@ -28,6 +28,13 @@ import Unique
 import GHC.Exts
 import System.IO.Unsafe	( unsafeInterleaveIO )
 
+#if __GLASGOW_HASKELL__ >= 607
+import GHC.IOBase (unsafeDupableInterleaveIO)
+#else
+unsafeDupableInterleaveIO :: IO a -> IO a
+unsafeDupableInterleaveIO = unsafeInterleaveIO
+#endif
+
 w2i x = word2Int# x
 i2w x = int2Word# x
 i2w_s x = (x :: Int#)
@@ -69,7 +76,7 @@ mkSplitUniqSupply (C# c#)
 
 	-- This is one of the most hammered bits in the whole compiler
 	mk_supply#
-	  = unsafeInterleaveIO (
+	  = unsafeDupableInterleaveIO (
 		genSymZh    >>= \ (I# u#) ->
 		mk_supply#  >>= \ s1 ->
 		mk_supply#  >>= \ s2 ->