re PR fortran/78758 (Warning: '__builtin_memcpy' ... overflows the destination…

re PR fortran/78758 (Warning: '__builtin_memcpy' ... overflows the destination for string assignment)

	PR fortran/78758
	* tree-object-size.c (compute_object_offset) <case ARRAY_REF>: Handle
	non-zero low bound or non-standard element sizes.

	* gfortran.dg/pr78758.f90: New test.
	* gfortran.dg/pr38868.f: Remove again bogus warning.

From-SVN: r243515

gcc/ChangeLog

 2016-12-10  Jakub Jelinek  <jakub@redhat.com>
 
+	PR fortran/78758
+	* tree-object-size.c (compute_object_offset) <case ARRAY_REF>: Handle
+	non-zero low bound or non-standard element sizes.
+
 	PR sanitizer/78708
 	* lto-streamer-in.c (input_function): In addition to debug stmts
 	without -g, remove IFN_*SAN_* calls if corresponding flag_sanitize

gcc/testsuite/ChangeLog

+2016-12-10  Jakub Jelinek  <jakub@redhat.com>
+
+	PR fortran/78758
+	* gfortran.dg/pr78758.f90: New test.
+	* gfortran.dg/pr38868.f: Remove again bogus warning.
+
 2016-12-09  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/77903

gcc/testsuite/gfortran.dg/pr38868.f

@@ -9,7 +9,7 @@
       ANER(1)='A   '
       ANER(2)='    '
       LINE=' '
-      LINE(78:80)='xyz'   ! { dg-warning "writing 3 bytes into a region of size 2" }
+      LINE(78:80)='xyz'
       WRITE(*,'(A82)') "'"//LINE//"'"
       END
 

gcc/testsuite/gfortran.dg/pr78758.f90

+! PR fortran/78758
+! { dg-do compile }
+! { dg-options "-O2 -Wall" }
+
+integer function pr78758 (x)
+  character(len=*), intent(in) :: x
+  character(len=16)            :: y
+  integer, external            :: z
+  y(2:) = " " // adjustl (x(2:))
+  pr78758 = z (y)
+end function pr78758

gcc/tree-object-size.c

@@ -138,13 +138,18 @@ compute_object_offset (const_tree expr, const_tree var)
 	return base;
 
       t = TREE_OPERAND (expr, 1);
+      tree low_bound, unit_size;
+      low_bound = array_ref_low_bound (CONST_CAST_TREE (expr));
+      unit_size = array_ref_element_size (CONST_CAST_TREE (expr));
+      if (! integer_zerop (low_bound))
+	t = fold_build2 (MINUS_EXPR, TREE_TYPE (t), t, low_bound);
       if (TREE_CODE (t) == INTEGER_CST && tree_int_cst_sgn (t) < 0)
 	{
 	  code = MINUS_EXPR;
 	  t = fold_build1 (NEGATE_EXPR, TREE_TYPE (t), t);
 	}
       t = fold_convert (sizetype, t);
-      off = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (TREE_TYPE (expr)), t);
+      off = size_binop (MULT_EXPR, unit_size, t);
       break;
 
     case MEM_REF: