https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71893
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Index: gcc/tree-ssa-sccvn.c
===================================================================
*** gcc/tree-ssa-sccvn.c (revision 238370)
--- gcc/tree-ssa-sccvn.c (working copy)
*************** copy_reference_ops_from_ref (tree ref, v
*** 810,815 ****
--- 810,818 ----
/* Always record lower bounds and element size. */
temp.op1 = array_ref_low_bound (ref);
temp.op2 = array_ref_element_size (ref);
+ /* array_ref_element_size forces the result to sizetype
+ even if that is the same as bitsizetype. */
+ STRIP_USELESS_TYPE_CONVERSION (temp.op2);
if (TREE_CODE (temp.op0) == INTEGER_CST
&& TREE_CODE (temp.op1) == INTEGER_CST
&& TREE_CODE (temp.op2) == INTEGER_CST)
