re PR tree-optimization/81744 (ICE: verify_ssa failed, at tree-ssa.c:1186)

	PR tree-optimization/81744
	* tree-predcom.c (prepare_finalizers_chain): Deep copy expr of
	loop's number of iterations.

	gcc/testsuite
	* gcc.dg/tree-ssa/pr81744.c: New.

From-SVN: r250950

gcc/ChangeLog

+2017-08-08  Bin Cheng  <bin.cheng@arm.com>
+
+	PR tree-optimization/81744
+	* tree-predcom.c (prepare_finalizers_chain): Deep copy expr of
+	loop's number of iterations.
+
 2017-08-08  Martin Liska  <mliska@suse.cz>
 
 	* asan.c: Include header files.

gcc/testsuite/ChangeLog

+2017-08-08  Bin Cheng  <bin.cheng@arm.com>
+
+	PR tree-optimization/81744
+	* gcc.dg/tree-ssa/pr81744.c: New.
+
 2017-08-08  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/81607

gcc/testsuite/gcc.dg/tree-ssa/pr81744.c

+/* { dg-do compile } */
+/* { dg-options "-O3 -fno-tree-loop-vectorize -fno-tree-slp-vectorize -fno-inline -fdump-tree-pcom-details" } */
+
+typedef struct {
+  int a, b;
+} CompandSegment;
+int a;
+CompandSegment *b;
+void fn1() {
+  for (; a; a++)
+    b[a].a = b[a].b = b[a - 1].a = b[a - 1].b = 0;
+}
+/* { dg-final { scan-tree-dump-times "Store-stores chain" 2 "pcom"} } */

gcc/tree-predcom.c

@@ -2940,7 +2940,7 @@ prepare_finalizers_chain (struct loop *loop, chain_p chain)
 
       if (TREE_CODE (niters) != INTEGER_CST && TREE_CODE (niters) != SSA_NAME)
 	{
-	  niters = copy_node (niters);
+	  niters = unshare_expr (niters);
 	  niters = force_gimple_operand (niters, &stmts, true, NULL);
 	  if (stmts)
 	    {