re PR tree-optimization/88069 (ICE in check_loop_closed_ssa_def, at tree-ssa-loop-manip.c:709)

2018-11-20  Jeff Law  <law@redhat.com>

	PR tree-optimization/88069
	* tree-ssa-dom.c (record_equivalences_from_phis): Propagate away
	degenerate virtual PHIs.

From-SVN: r266343

gcc/ChangeLog

+2018-11-20  Jeff Law  <law@redhat.com>
+
+	PR tree-optimization/88069
+	* tree-ssa-dom.c (record_equivalences_from_phis): Propagate away
+	degenerate virtual PHIs.
+
 2018-11-21  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR target/87317

gcc/tree-ssa-dom.c

@@ -1106,10 +1106,13 @@ record_equivalences_from_phis (basic_block bb)
 {
   gphi_iterator gsi;
 
-  for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+  for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); )
     {
       gphi *phi = gsi.phi ();
 
+      /* We might eliminate the PHI, so advance GSI now.  */
+      gsi_next (&gsi);
+
       tree lhs = gimple_phi_result (phi);
       tree rhs = NULL;
       size_t i;
@@ -1159,9 +1162,26 @@ record_equivalences_from_phis (basic_block bb)
 	 this, since this is a true assignment and not an equivalence
 	 inferred from a comparison.  All uses of this ssa name are dominated
 	 by this assignment, so unwinding just costs time and space.  */
-      if (i == gimple_phi_num_args (phi)
-	  && may_propagate_copy (lhs, rhs))
+      if (i == gimple_phi_num_args (phi))
+	{
+	  if (may_propagate_copy (lhs, rhs))
 	    set_ssa_name_value (lhs, rhs);
+	  else if (virtual_operand_p (lhs))
+	    {
+	      gimple *use_stmt;
+	      imm_use_iterator iter;
+	      use_operand_p use_p;
+	      /* For virtual operands we have to propagate into all uses as
+	         otherwise we will create overlapping life-ranges.  */
+	      FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
+	        FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
+	          SET_USE (use_p, rhs);
+	      if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
+	        SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs) = 1;
+	      gimple_stmt_iterator tmp_gsi = gsi_for_stmt (phi);
+	      remove_phi_node (&tmp_gsi, true);
+	    }
+	}
     }
 }