[Bug tree-optimization/84362] [7/8/9 Regression] Auto-vectorization regression when accessing member variable through getter/accessor

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84362

--- Comment #6 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 18 Dec 2018, jakub at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84362
> 
> --- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
> The MEM_REF is in there because we first create a _ZNK3vec4sizeEv.isra.0 clone
> which takes unsigned int argument and just passes it through.
> So, does LIM need to fold the MEM_EXPRs in a similar way to how PRE folds them
> to figure out it is the same thing as v.size?

The bug somehow felt off my radar.  The issue is (IIRC we have some
duplicates here) that LIM uses simple iterative_hash_expr and
operand_equal_p to equate refs.  IIRC I had (partial) patches
somewhere to improve the situation here but I can't find them.

It might be possible to simply substitute mem_ref_hasher with
expr_hash_elt from tree-ssa-scopedtables.h.  Let me explore this.