re PR tree-optimization/84552 (Compile time hog w/ -O2 -floop-nest-optimize…

re PR tree-optimization/84552 (Compile time hog w/ -O2 -floop-nest-optimize -fno-tree-copy-prop -fno-tree-fre -fno-tree-loop-ivcanon)

2018-03-08  Richard Biener  <rguenther@suse.de>

	PR middle-end/84552
	* tree-scalar-evolution.c: Include tree-into-ssa.h.
	(follow_copies_to_constant): Do not follow SSA names registered
	for update.

	* gcc.dg/graphite/pr84552.c: New testcase.

From-SVN: r258365

gcc/ChangeLog

 2018-03-08  Richard Biener  <rguenther@suse.de>
 
+	PR middle-end/84552
+	* tree-scalar-evolution.c: Include tree-into-ssa.h.
+	(follow_copies_to_constant): Do not follow SSA names registered
+	for update.
+
+2018-03-08  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/84178
 	* tree-if-conv.c (combine_blocks): Move insert_gimplified_predicates
 	to caller.

gcc/testsuite/ChangeLog

 2018-03-08  Richard Biener  <rguenther@suse.de>
 
+	PR middle-end/84552
+	* gcc.dg/graphite/pr84552.c: New testcase.
+
+2018-03-08  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/84178
 	* gcc.dg/torture/pr84178-2.c: New testcase.
 

gcc/testsuite/gcc.dg/graphite/pr84552.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -floop-nest-optimize -fno-tree-copy-prop -fno-tree-fre -fno-tree-loop-ivcanon" } */
+
+int cx;
+
+int
+e6 (int pj, int xe)
+{
+  for (cx = 0; cx < 2; ++cx)
+    while (xe < 1)
+      {
+	for (cx = 0; cx < 2; ++cx)
+	  pj *= 2;
+
+	if (cx != 0)
+	  goto o3;
+
+	++xe;
+      }
+
+o3:
+  return pj;
+}

gcc/tree-scalar-evolution.c

@@ -280,6 +280,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "params.h"
 #include "tree-ssa-propagate.h"
 #include "gimple-fold.h"
+#include "tree-into-ssa.h"
 
 static tree analyze_scalar_evolution_1 (struct loop *, tree);
 static tree analyze_scalar_evolution_for_address_of (struct loop *loop,
@@ -1540,7 +1541,10 @@ static tree
 follow_copies_to_constant (tree var)
 {
   tree res = var;
-  while (TREE_CODE (res) == SSA_NAME)
+  while (TREE_CODE (res) == SSA_NAME
+	 /* We face not updated SSA form in multiple places and this walk
+	    may end up in sibling loops so we have to guard it.  */
+	 && !name_registered_for_update_p (res))
     {
       gimple *def = SSA_NAME_DEF_STMT (res);
       if (gphi *phi = dyn_cast <gphi *> (def))