[PATCH] Fix PR88229

[Richard Biener]

Bootstrapped and tested on x86_64-unknonw-linux-gnu, applied.

Richard.

2018-11-28  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/88229
        * tree-ssa.c (non_rewritable_mem_ref_base): Check DECL_SIZE_UNIT
        is an INTEGER_CST before accessing it so.

diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index bd8b91f8b4b..e3eb4b05130 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -1446,6 +1446,7 @@ non_rewritable_mem_ref_base (tree ref)
        return NULL_TREE;
       /* For integral typed extracts we can use a BIT_FIELD_REF.  */
       if (DECL_SIZE (decl)
+         && TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST
          && (known_subrange_p
              (mem_ref_offset (base),
               wi::to_poly_offset (TYPE_SIZE_UNIT (TREE_TYPE (base))),