From ce9d03fa27ce85072d8ac1426d5420a5c0c215ee Mon Sep 17 00:00:00 2001
From: simonmar <unknown>
Date: Tue, 3 Jan 2006 12:56:10 +0000
Subject: [PATCH] [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.
---
 ghc/rts/Exception.cmm |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/ghc/rts/Exception.cmm b/ghc/rts/Exception.cmm
index dc6305c..9d8d9d6 100644
--- 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! */
 
-- 
1.7.10.4