re PR tree-optimization/87349 (ICE: Segmentation fault (in useless_type_conversion_p or is_gimple_reg_type))

2018-09-19  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/87349
	PR tree-optimization/87342
	* tree-ssa-sccvn.c (do_rpo_vn): Iterate max_rpo computation.

	* gcc.dg/torture/pr87349-1.c: New testcase.
	* gcc.dg/torture/pr87349-2.c: Likewise.
	* gcc.dg/torture/pr87342.c: Likewise.

From-SVN: r264419

gcc/ChangeLog

@@ -1,3 +1,9 @@
+2018-09-19  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/87349
+	PR tree-optimization/87342
+	* tree-ssa-sccvn.c (do_rpo_vn): Iterate max_rpo computation.
+
 2018-09-18  Marek Polacek  <polacek@redhat.com>
 
 	P1064R0 - Allowing Virtual Function Calls in Constant Expressions

gcc/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2018-09-19  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/87349
+	PR tree-optimization/87342
+	* gcc.dg/torture/pr87349-1.c: New testcase.
+	* gcc.dg/torture/pr87349-2.c: Likewise.
+	* gcc.dg/torture/pr87342.c: Likewise.
+
 2018-09-18  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	PR fortran/29550

gcc/testsuite/gcc.dg/torture/pr87342.c

@@ -0,0 +1,44 @@
+/* { dg-do compile } */
+
+int ix;
+
+void
+o6 (int rh)
+{
+  if (rh == 0)
+    {
+      ix = 0;
+      while (ix < 1)
+	{
+	}
+
+      for (;;)
+	if (ix == 0)
+	  while (rh < 1)
+	    {
+	      if (rh == 0)
+		{
+		  __builtin_unreachable ();
+
+kp:
+		  if (ix == 0)
+		    {
+hk:
+		      ix = 0;
+		    }
+		}
+
+	      while (rh < 1)
+		if (ix == 0)
+		  goto kp;
+
+	      while (rh < 1)
+		{
+		}
+	    }
+	else
+	  goto kp;
+    }
+
+  goto hk;
+}

gcc/testsuite/gcc.dg/torture/pr87349-1.c

@@ -0,0 +1,33 @@
+/* { dg-do compile } */
+
+void
+h1 (int *fh, int pw)
+{
+  *fh = 0;
+  if (*fh != 0)
+    for (;;)
+      {
+	fh = &pw;
+
+	if (pw == 0)
+	  {
+	  }
+	else
+	  while (pw < 1)
+	    {
+	      if (pw == 0)
+		{
+ut:
+		  ;
+		}
+
+	      ++pw;
+	    }
+
+	if (pw == 0)
+	  goto ut;
+      }
+
+  goto ut;
+}
+

gcc/testsuite/gcc.dg/torture/pr87349-2.c

@@ -0,0 +1,33 @@
+/* { dg-do compile } */
+
+void
+h1 (int *fh, int pw)
+{
+  *fh = 0;
+  if (*fh != 0)
+    for (;;)
+      {
+	fh = &pw;
+
+	if (pw == 0)
+	  {
+	  }
+	else
+	  while (pw < 1)
+	    {
+	      if (pw == 0)
+		{
+ut:
+		  ;
+		}
+
+	      ++pw;
+	    }
+
+	if (pw == *fh)
+	  goto ut;
+      }
+
+  goto ut;
+}
+

gcc/tree-ssa-sccvn.c

@@ -6374,6 +6374,7 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs,
   vn_valueize = rpo_vn_valueize;
 
   /* Initialize the unwind state and edge/BB executable state.  */
+  bool need_max_rpo_iterate = false;
   for (int i = 0; i < n; ++i)
     {
       basic_block bb = BASIC_BLOCK_FOR_FN (fn, rpo[i]);
@@ -6388,11 +6389,14 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs,
 	  if (e->flags & EDGE_DFS_BACK)
 	    has_backedges = true;
 	  e->flags &= ~EDGE_EXECUTABLE;
-	  if (e == entry)
+	  if (iterate || e == entry)
 	    continue;
 	  if (bb_to_rpo[e->src->index] > i)
-	    rpo_state[i].max_rpo = MAX (rpo_state[i].max_rpo,
-					bb_to_rpo[e->src->index]);
+	    {
+	      rpo_state[i].max_rpo = MAX (rpo_state[i].max_rpo,
+					  bb_to_rpo[e->src->index]);
+	      need_max_rpo_iterate = true;
+	    }
 	  else
 	    rpo_state[i].max_rpo
 	      = MAX (rpo_state[i].max_rpo,
@@ -6403,6 +6407,35 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs,
   entry->flags |= EDGE_EXECUTABLE;
   entry->dest->flags |= BB_EXECUTABLE;
 
+  /* When there are irreducible regions the simplistic max_rpo computation
+     above for the case of backedges doesn't work and we need to iterate
+     until there are no more changes.  */
+  unsigned nit = 0;
+  while (need_max_rpo_iterate)
+    {
+      nit++;
+      need_max_rpo_iterate = false;
+      for (int i = 0; i < n; ++i)
+	{
+	  basic_block bb = BASIC_BLOCK_FOR_FN (fn, rpo[i]);
+	  edge e;
+	  edge_iterator ei;
+	  FOR_EACH_EDGE (e, ei, bb->preds)
+	    {
+	      if (e == entry)
+		continue;
+	      int max_rpo = MAX (rpo_state[i].max_rpo,
+				 rpo_state[bb_to_rpo[e->src->index]].max_rpo);
+	      if (rpo_state[i].max_rpo != max_rpo)
+		{
+		  rpo_state[i].max_rpo = max_rpo;
+		  need_max_rpo_iterate = true;
+		}
+	    }
+	}
+    }
+  statistics_histogram_event (cfun, "RPO max_rpo iterations", nit);
+
   /* As heuristic to improve compile-time we handle only the N innermost
      loops and the outermost one optimistically.  */
   if (iterate)