PR middle-end/92952 - gfortran.dg/lto/pr87689 FAILs at -O2

gcc/ChangeLog:
	* builtins.c (compute_objsize): Adjust offset by the array low bound.

From-SVN: r279445

gcc/ChangeLog

+2019-12-16  Martin Sebor  <msebor@redhat.com>
+
+	PR middle-end/92952
+	* builtins.c (compute_objsize): Adjust offset by the array low bound.
+
 2019-12-16  David Malcolm  <dmalcolm@redhat.com>
 
 	* pretty-print.c (pp_write_text_as_html_like_dot_to_stream): New

gcc/builtins.c

@@ -3999,6 +3999,16 @@ compute_objsize (tree dest, int ostype, tree *pdecl /* = NULL */,
 	     above.  */
 	  if (TREE_CODE (dest) == ARRAY_REF)
 	    {
+	      tree lowbnd = array_ref_low_bound (dest);
+	      if (!integer_zerop (lowbnd) && tree_fits_uhwi_p (lowbnd))
+		{
+		  /* Adjust the offset by the low bound of the array
+		     domain (normally zero but 1 in Fortran).  */
+		  unsigned HOST_WIDE_INT lb = tree_to_uhwi (lowbnd);
+		  offrng[0] -= lb;
+		  offrng[1] -= lb;
+		}
+
 	      /* Convert the array index into a byte offset.  */
 	      tree eltype = TREE_TYPE (dest);
 	      tree tpsize = TYPE_SIZE_UNIT (eltype);