rtl-optimization/105577 - RTL DSE and non-call EH

When one of the first two stages of DSE removes a throwing stmt
we have to purge dead EH edges before the DF re-analyze fires off
a fast DCE since that cannot cope with the situation.

2022-05-12  Richard Biener  <rguenther@suse.de>

	PR rtl-optimization/105577
	* dse.cc (rest_of_handle_dse): Make sure to purge dead EH
	edges before running fast DCE via df_analyze.

(cherry picked from commit dfda40f8147412328f699628a54b0aaa584776e7)

diff --git a/gcc/dse.cc b/gcc/dse.cc
index b8914a3..bb658a8 100644 (file)
--- a/gcc/dse.cc
+++ b/gcc/dse.cc
@@ -3682,6 +3682,16 @@ rest_of_handle_dse (void)
 
   dse_step0 ();
   dse_step1 ();
+  /* DSE can eliminate potentially-trapping MEMs.
+     Remove any EH edges associated with them, since otherwise
+     DF_LR_RUN_DCE will complain later.  */
+  if ((locally_deleted || globally_deleted)
+      && cfun->can_throw_non_call_exceptions
+      && purge_all_dead_edges ())
+    {
+      free_dominance_info (CDI_DOMINATORS);
+      delete_unreachable_blocks ();
+    }
   dse_step2_init ();
   if (dse_step2 ())
     {