Re: [PATCH] Fix ix86_split_long_move collision handling with TLS (PR target/66470)

[Uros Bizjak <ubizjak at gmail dot com>]

On Tue, Jun 9, 2015 at 6:21 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Tue, Jun 09, 2015 at 06:16:32PM +0200, Uros Bizjak wrote:
>> > something?  Would it be acceptable to just guard the changes in the patch
>> > with !TARGET_X32 and let H.J. deal with that target?  I'm afraid I'm lost
>> > when to ZERO_EXTEND addr (if needed at all), etc.
>>
>> If you wish, I can take your patch and take if further. -mx32 is a
>> delicate beast...
>
> If you could, it would be appreciated, I'm quite busy with OpenMP 4.1 stuff
> now.
> Note that for -m64/-mx32 it will be much harder to create a reproducer,
> because to trigger the bug one has to convince the register allocator
> to allocate the lhs of the load in certain registers (not that hard),
> but also the index register (to be scaled, also not that hard) and
> also the register holding the tls symbol immediate.  Wonder if one has to
> keep all but the two registers live across the load or something similar.

Please find attach a patch that takes your idea slightly further. We
find  perhaps zero-extended UNSPEC_TP, and copy it for further use. At
its place, we simply slap const0_rtx. We know that address to
multi-word values has to be offsettable, which in case of x32 means
that it is NOT zero-extended address.

Uros.

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