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Re: [vta,trunk?] stabilize hashing of SSA names and builtin function DECLs
On Wed, Oct 29, 2008 at 8:19 PM, Alexandre Oliva <aoliva@redhat.com> wrote:
> On Oct 29, 2008, "Richard Guenther" <richard.guenther@gmail.com> wrote:
>
>> + val = iterative_hash_host_wide_int (DECL_UID (SSA_NAME_VAR (t)), val);
>> + val = iterative_hash_host_wide_int (SSA_NAME_VERSION (t), val);
>
>> why both? I would say using SSA_NAME_VERSION should be enough?
>
> Enough, it is, sure. I figured rocking the boat a bit further might
> make for better hashing. No evidence of that, though.
>
The problem is that if you hash on DECL_UID as well, it will hide
problems where people are keeping ssa names that have been freed in
hash tables (since versions get reused but decl_uid would be
different).
This has actually happened in the past
:)