https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63679
--- Comment #37 from alalaw01 at gcc dot gnu.org ---
Hmmm, no it's not the hashing - that pretty much ignores all types. It's the
comparison in hashable_expr_equal_p, which just uses operand_equal_p,
specifically this part (in fold-const.c):
case MEM_REF:
/* Require equal access sizes, and similar pointer types.
We can have incomplete types for array references of
variable-sized arrays from the Fortran frontend
though. Also verify the types are compatible. */
if (!((TYPE_SIZE (TREE_TYPE (arg0)) == TYPE_SIZE (TREE_TYPE (arg1))
|| (TYPE_SIZE (TREE_TYPE (arg0))
&& TYPE_SIZE (TREE_TYPE (arg1))
&& operand_equal_p (TYPE_SIZE (TREE_TYPE (arg0)),
TYPE_SIZE (TREE_TYPE (arg1)),
flags)))
&& types_compatible_p (TREE_TYPE (arg0), TREE_TYPE (arg1))
&& ((flags & OEP_ADDRESS_OF)
|| (alias_ptr_types_compatible_p
(TREE_TYPE (TREE_OPERAND (arg0, 1)),
TREE_TYPE (TREE_OPERAND (arg1, 1)))
&& (MR_DEPENDENCE_CLIQUE (arg0)
== MR_DEPENDENCE_CLIQUE (arg1))
&& (MR_DEPENDENCE_BASE (arg0)
== MR_DEPENDENCE_BASE (arg1))
&& (TYPE_ALIGN (TREE_TYPE (arg0))
== TYPE_ALIGN (TREE_TYPE (arg1)))))))
specifically, a pointer to int, and a pointer to an array of int, are not
alias_ptr_types_compatible_p. (I'm not clear that they should be, either!?)
