[project @ 2006-01-03 12:56:10 by simonmar]

two fixes for the case when a (synchronous) exception is propagated to
the top of a thread's stack, i.e. it is unhandled.

  1. store the exception in the right place (we were using the
     OFFSET_StgTSO_stack macro and not accounting for the TSO's
     header size)

  2. put an stg_enter_info on the stack so that the GC can understand
     this thread's stack.

diff --git a/ghc/rts/Exception.cmm b/ghc/rts/Exception.cmm
index dc6305c..9d8d9d6 100644 (file)
--- a/ghc/rts/Exception.cmm
+++ b/ghc/rts/Exception.cmm
@@ -378,10 +378,15 @@ retry_pop_stack:
     }
 
     if (frame_type == STOP_FRAME) {
-       /* We've stripped the entire stack, the thread is now dead. */
-       Sp = CurrentTSO + OFFSET_StgTSO_stack 
-               + WDS(StgTSO_stack_size(CurrentTSO)) - WDS(1);
-       Sp(0) = R1;             /* save the exception */
+       /*
+        * We've stripped the entire stack, the thread is now dead.
+        * We will leave the stack in a GC'able state, see the stg_stop_thread
+        * entry code in StgStartup.cmm.
+        */
+       Sp = CurrentTSO + TSO_OFFSET_StgTSO_stack 
+               + WDS(StgTSO_stack_size(CurrentTSO)) - WDS(2);
+       Sp(1) = R1;             /* save the exception */
+       Sp(0) = stg_enter_info; /* so that GC can traverse this stack */
        StgTSO_what_next(CurrentTSO) = ThreadKilled::I16;
        SAVE_THREAD_STATE();    /* inline! */