re PR rtl-optimization/88018 (ICE in insert_insn_on_edge at cfgrtl.c:1952 since r255066)

	PR rtl-optimization/88018
	* cfgrtl.c (fixup_abnormal_edges): Guard moving insns to fallthru edge
	on the presence of fallthru edge, rather than if it is a USE or not.

	* g++.dg/tsan/pr88018.C: New test.

From-SVN: r266174

gcc/ChangeLog

+2018-11-15  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/88018
+	* cfgrtl.c (fixup_abnormal_edges): Guard moving insns to fallthru edge
+	on the presence of fallthru edge, rather than if it is a USE or not.
+
 2018-11-15  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/87917

gcc/cfgrtl.c

@@ -3332,8 +3332,15 @@ fixup_abnormal_edges (void)
 			 If it's placed after a trapping call (i.e. that
 			 call is the last insn anyway), we have no fallthru
 			 edge.  Simply delete this use and don't try to insert
-			 on the non-existent edge.  */
-		      if (GET_CODE (PATTERN (insn)) != USE)
+			 on the non-existent edge.
+			 Similarly, sometimes a call that can throw is
+			 followed in the source with __builtin_unreachable (),
+			 meaning that there is UB if the call returns rather
+			 than throws.  If there weren't any instructions
+			 following such calls before, supposedly even the ones
+			 we've deleted aren't significant and can be
+			 removed.  */
+		      if (e)
 			{
 			  /* We're not deleting it, we're moving it.  */
 			  insn->set_undeleted ();

gcc/testsuite/ChangeLog

+2018-11-15  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/88018
+	* g++.dg/tsan/pr88018.C: New test.
+
 2018-11-15  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/87917