[commit: ghc] ghc-7.4: Fix silly bug in casMutVar#: I forgot the GC write barrier (78b3123)

[Ian Lynagh]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : ghc-7.4

http://hackage.haskell.org/trac/ghc/changeset/78b312369b1e07edd5c3c098f2822ee096654465

>---------------------------------------------------------------

commit 78b312369b1e07edd5c3c098f2822ee096654465
Author: Simon Marlow <marlowsd at gmail.com>
Date:   Fri Dec 9 09:09:42 2011 +0000

    Fix silly bug in casMutVar#: I forgot the GC write barrier

>---------------------------------------------------------------

 rts/PrimOps.cmm |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/rts/PrimOps.cmm b/rts/PrimOps.cmm
index 21ac05f..8475555 100644
--- a/rts/PrimOps.cmm
+++ b/rts/PrimOps.cmm
@@ -284,6 +284,9 @@ stg_casMutVarzh
     if (h != old) {
         RET_NP(1,h);
     } else {
+        if (GET_INFO(mv) == stg_MUT_VAR_CLEAN_info) {
+           foreign "C" dirty_MUT_VAR(BaseReg "ptr", mv "ptr") [];
+        }
         RET_NP(0,h);
     }
 }