X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;ds=sidebyside;f=ghc%2Frts%2FStgStartup.cmm;fp=ghc%2Frts%2FStgStartup.cmm;h=d727cb573f0ddb2c41856191ae1c8b9fda0975f2;hb=3595da95b2ca0d60c9100f77541b6ce36e49363c;hp=2d5d4d89415270204b8f8a00012bd18eb47d08cf;hpb=eab2c6c48c6d0d679e2a737388749ac482372110;p=ghc-hetmet.git

diff --git a/ghc/rts/StgStartup.cmm b/ghc/rts/StgStartup.cmm
index 2d5d4d8..d727cb5 100644
--- a/ghc/rts/StgStartup.cmm
+++ b/ghc/rts/StgStartup.cmm
@@ -102,6 +102,9 @@ INFO_TABLE_RET( stg_stop_thread, STOP_THREAD_WORDS, STOP_THREAD_BITMAP,
    Start a thread from the scheduler by returning to the address on
    the top of the stack.  This is used for all entries to STG code
    from C land.
+
+   On the way back, we (usually) pass through stg_returnToSched which saves
+   the thread's state away nicely.
    -------------------------------------------------------------------------- */
 
 stg_returnToStackTop
@@ -111,6 +114,24 @@ stg_returnToStackTop
   jump %ENTRY_CODE(Sp(0));
 }
 
+stg_returnToSched
+{
+  SAVE_THREAD_STATE();
+  foreign "C" threadPaused(CurrentTSO);
+  jump StgReturn;
+}
+
+// A variant of stg_returnToSched, but instead of returning directly to the
+// scheduler, we jump to the code fragment pointed to by R2.  This lets us
+// perform some final actions after making the thread safe, such as unlocking
+// the MVar on which we are about to block in SMP mode.
+stg_returnToSchedButFirst
+{
+  SAVE_THREAD_STATE();
+  foreign "C" threadPaused(CurrentTSO);
+  jump R2;
+}
+
 /* -----------------------------------------------------------------------------
     Strict IO application - performing an IO action and entering its result.