re PR tree-optimization/84383 (ICE in maybe_diag_stxncpy_trunc)

	PR tree-optimization/84383
	* tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Don't look at
	dstoff nor call operand_equal_p if dstbase is NULL.

	* gcc.c-torture/compile/pr84383.c: New test.

From-SVN: r257684

gcc/ChangeLog

 2018-02-15  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/84383
+	* tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Don't look at
+	dstoff nor call operand_equal_p if dstbase is NULL.
+
 	PR tree-optimization/84334
 	* match.pd ((A +- CST1) +- CST2 -> A + CST3): If A is
 	also a CONSTANT_CLASS_P, punt.

gcc/testsuite/ChangeLog

 2018-02-15  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/84383
+	* gcc.c-torture/compile/pr84383.c: New test.
+
 	PR tree-optimization/84334
 	* gcc.dg/pr84334.c: New test.
 

gcc/testsuite/gcc.c-torture/compile/pr84383.c

+/* PR tree-optimization/84383 */
+
+struct S { char *s; };
+void bar (struct S *);
+
+void
+foo (int a, char *b)
+{
+  struct S c[4];
+  bar (c);
+  __builtin_strncpy (c[a].s, b, 32);
+  c[a].s[31] = '\0';
+  bar (c);
+}

gcc/tree-ssa-strlen.c

@@ -1878,6 +1878,7 @@ maybe_diag_stxncpy_trunc (gimple_stmt_iterator gsi, tree src, tree cnt)
       poly_int64 lhsoff;
       tree lhsbase = get_addr_base_and_unit_offset (lhs, &lhsoff);
       if (lhsbase
+	  && dstbase
 	  && known_eq (dstoff, lhsoff)
 	  && operand_equal_p (dstbase, lhsbase, 0))
 	return false;