X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Frts%2FGC.c;h=a0f119f5ce5926b5255121f5d5db691b3e80858a;hb=25efe5a45ff5579172312ca14cfd89443ba931dc;hp=2b30d679f90a267ee0dec1f8f4fc2f25db661e27;hpb=b3f530814c15886a7a010ed871bb1f054a3918b3;p=ghc-hetmet.git

diff --git a/ghc/rts/GC.c b/ghc/rts/GC.c
index 2b30d67..a0f119f 100644
--- a/ghc/rts/GC.c
+++ b/ghc/rts/GC.c
@@ -1,5 +1,5 @@
 /* -----------------------------------------------------------------------------
- * $Id: GC.c,v 1.149 2003/03/24 14:46:53 simonmar Exp $
+ * $Id: GC.c,v 1.150 2003/03/24 15:33:25 simonmar Exp $
  *
  * (c) The GHC Team 1998-2003
  *
@@ -2002,9 +2002,22 @@ eval_thunk_selector( nat field, StgSelector * p )
 
 selector_loop:
 
+    // We don't want to end up in to-space, because this causes
+    // problems when the GC later tries to evacuate the result of
+    // eval_thunk_selector().  There are various ways this could
+    // happen:
+    //
+    // - following an IND_STATIC
+    //
+    // - when the old generation is compacted, the mark phase updates
+    //   from-space pointers to be to-space pointers, and we can't
+    //   reliably tell which we're following (eg. from an IND_STATIC).
+    // 
+    // So we use the block-descriptor test to find out if we're in
+    // to-space.
+    //
     if (Bdescr((StgPtr)selectee)->flags & BF_EVACUATED) {
-	SET_INFO(p, info_ptr);
-	return NULL;
+	goto bale_out;
     }
 
     info = get_itbl(selectee);
@@ -2021,12 +2034,15 @@ selector_loop:
 	  ASSERT(field <  (StgWord32)(info->layout.payload.ptrs + 
 				      info->layout.payload.nptrs));
 	  
+	  // ToDo: shouldn't we test whether this pointer is in
+	  // to-space?
 	  return selectee->payload[field];
 
       case IND:
       case IND_PERM:
       case IND_OLDGEN:
       case IND_OLDGEN_PERM:
+      case IND_STATIC:
 	  selectee = ((StgInd *)selectee)->indirectee;
 	  goto selector_loop;
 
@@ -2036,11 +2052,6 @@ selector_loop:
 	  // leaks by evaluating this selector thunk anyhow.
 	  break;
 
-      case IND_STATIC:
-	  // We can't easily tell whether the indirectee is into 
-	  // from or to-space, so just bail out here.
-	  break;
-
       case THUNK_SELECTOR:
       {
 	  StgClosure *val;
@@ -2113,6 +2124,7 @@ selector_loop:
 	     (int)(info->type));
     }
 
+bale_out:
     // We didn't manage to evaluate this thunk; restore the old info pointer
     SET_INFO(p, info_ptr);
     return NULL;