re PR tree-optimization/66768 (address space gets lost on literal pointer)

	PR tree-optimization/66768
	* tree-ssa-loop-ivopts.c (find_interesting_uses_address): Skip addr
	iv_use if base object can't be determined.

	gcc/testsuite
	* gcc.target/i386/pr66768.c: New test.

From-SVN: r245837

gcc/ChangeLog

+2017-03-02  Bin Cheng  <bin.cheng@arm.com>
+
+	PR tree-optimization/66768
+	* tree-ssa-loop-ivopts.c (find_interesting_uses_address): Skip addr
+	iv_use if base object can't be determined.
+
 2017-03-02  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/79345

gcc/testsuite/ChangeLog

+2017-03-02  Bin Cheng  <bin.cheng@arm.com>
+
+	PR tree-optimization/66768
+	* gcc.target/i386/pr66768.c: New test.
+
 2017-03-02  Richard Biener  <rguenther@suse.de>
 
 	* gcc.dg/rtl/x86_64/dfinit.c: Only run for lp64.

gcc/testsuite/gcc.target/i386/pr66768.c

+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+typedef __seg_gs struct foo_s {
+  int a[20];
+} foo_t;
+
+int sum(void)
+{
+  const foo_t *p = (const foo_t *)0x1234;
+  int i, total=0;
+  for (i=0; i<20; i++)
+    total += p->a[i];
+  return total;
+}
+
+/* { dg-final { scan-assembler "add*.\[ \t\]%gs:" } } */

gcc/tree-ssa-loop-ivopts.c

@@ -2324,6 +2324,10 @@ find_interesting_uses_address (struct ivopts_data *data, gimple *stmt,
     }
 
   civ = alloc_iv (data, base, step);
+  /* Fail if base object of this memory reference is unknown.  */
+  if (civ->base_object == NULL_TREE)
+    goto fail;
+
   record_group_use (data, op_p, civ, stmt, USE_ADDRESS);
   return;