Re: [path] PR 54900: store data race in if-conversion pass

[Aldy Hernandez <aldyh at redhat dot com>]

On 10/16/12 13:28, Jakub Jelinek wrote:

> I see another problem with noce_can_store_speculate_p, the return false;
> checks.  The search for a store to exactly that location can be done
> just on post dominator bbs, but I wonder how you can avoid looking for
> volatile insns or non-const/pure calls (or insns that may modify
> the address) also in other bbs.
> What if there is:
>    location of considered if-conversion on mem
>    if (some_condition)
>      call ();
>    mem = something;

Are we not currently being conservative in the current code and 
returning false once we see a volatile or a non-const call?

> ?  We only walk immediate post-dominators, so look at the bb containing
> mem = something;, but I think a call/volatile insn/modification of mem's
> address is problematic in any bb on any path in between test_bb and
> the post-dominator on which the write has been found.
>
> 	Jakub