re PR tree-optimization/88074 (g++ hangs on math expression)

2018-11-20  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/88074
	* tree-ssa-dom.c (pass_dominator::execute): Do not walk
	backedges.

	* gcc.dg/pr88074.c: New testcase.

From-SVN: r266313

gcc/ChangeLog

 2018-11-20  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/88074
+	* tree-ssa-dom.c (pass_dominator::execute): Do not walk
+	backedges.
+
+2018-11-20  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/88069
 	* tree-ssa-sccvn.c (visit_phi): Do not value-number to unvisited
 	virtual PHI arguments.

gcc/testsuite/ChangeLog

+2018-11-20  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/88074
+	* gcc.dg/pr88074.c: New testcase.
+
 2018-11-20  Martin Liska  <mliska@suse.cz>
 
 	* pr57362.C: Move to g++.target/i386 folder.

gcc/testsuite/gcc.dg/gomp/pr88105.c

+/* { dg-do compile } */
+/* { dg-options "-fopenmp -O -fexceptions -fnon-call-exceptions -fno-tree-fre" } */
+
+int
+s0 (void)
+{
+  int g6, oh = 0;
+  int *a6 = &g6;
+
+  (void) a6;
+
+#pragma omp parallel for
+  for (g6 = 0; g6 < 1; ++g6)
+    {
+      int zk;
+
+      for (zk = 0; zk < 1; ++zk)
+        {
+          oh += zk / (zk + 1);
+
+          for (;;)
+            {
+            }
+        }
+
+      a6 = &zk;
+    }
+
+  return oh;
+}

gcc/tree-ssa-dom.c

@@ -777,7 +777,8 @@ pass_dominator::execute (function *fun)
 	  if (bb == NULL)
 	    continue;
 	  while (single_succ_p (bb)
-		 && (single_succ_edge (bb)->flags & EDGE_EH) == 0)
+		 && (single_succ_edge (bb)->flags
+		     & (EDGE_EH|EDGE_DFS_BACK)) == 0)
 	    bb = single_succ (bb);
 	  if (bb == EXIT_BLOCK_PTR_FOR_FN (fun))
 	    continue;