Fix PR48794 some more

[Michael Matz]

Hi,

On Wed, 25 Jan 2012, Michael Matz wrote:

> so, the below adjusted testcase from PR48794 still fails for the same 
> reasons (regions still referenced from RESX being removed).  I was split 
> minds about if that's a new bug or just an extension of the old bug, so 
> I hijacked the old PR.  In any case, remove_unreachable_handlers_no_lp 
> needs similar handling like remove_unreachable_handlers.
> 
> Patch fixes the segfault and is currently in regstrapping on x86_64-linux.  
> Okay for trunk?

Actually, resx/eh_dispatch always are the last BB statements, so the loop 
doesn't need to look at all statements in a BB, making it quite somewhat 
faster.  Consider the tree-eh.c to be looking like so:

Index: tree-eh.c
===================================================================
--- tree-eh.c   (revision 183524)
+++ tree-eh.c   (working copy)
@@ -3617,14 +3617,40 @@ remove_unreachable_handlers_no_lp (void)
 {
   eh_region r;
   int i;
+  sbitmap r_reachable;
+  basic_block bb;
+
+  r_reachable = sbitmap_alloc (VEC_length (eh_region, cfun->eh->region_array));
+  sbitmap_zero (r_reachable);
+
+  FOR_EACH_BB (bb)
+    {
+      gimple stmt = last_stmt (bb);
+      if (stmt)
+       /* Avoid removing regions referenced from RESX/EH_DISPATCH.  */
+       switch (gimple_code (stmt))
+         {
+         case GIMPLE_RESX:
+           SET_BIT (r_reachable, gimple_resx_region (stmt));
+           break;
+         case GIMPLE_EH_DISPATCH:
+           SET_BIT (r_reachable, gimple_eh_dispatch_region (stmt));
+           break;
+         default:
+           break;
+         }
+    }

   for (i = 1; VEC_iterate (eh_region, cfun->eh->region_array, i, r); ++i)
-    if (r && r->landing_pads == NULL && r->type != ERT_MUST_NOT_THROW)
+    if (r && r->landing_pads == NULL && r->type != ERT_MUST_NOT_THROW
+       && !TEST_BIT (r_reachable, i))
       {
        if (dump_file)
          fprintf (dump_file, "Removing unreachable region %d\n", i);
        remove_eh_handler (r);
       }
+
+  sbitmap_free (r_reachable);
 }

 /* Undo critical edge splitting on an EH landing pad.  Earlier, we


Ciao,
Michael.