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Re: Autoinc vs reload and LRA
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Bernd Schmidt <bernds_cb1 at t-online dot de>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 27 Nov 2019 18:41:48 -0600
- Subject: Re: Autoinc vs reload and LRA
- References: <56a4653b-ca0f-0cb9-f0ec-43027a2da8dd@t-online.de>
On Mon, Nov 25, 2019 at 09:22:55PM +0100, Bernd Schmidt wrote:
> So I was curious what would happen if I turned on LRA for m68k. It turns
> out my autoinc patches from the cc0 patch set expose a bug in how LRA
> handles autoincrement. While it copies the logic from reload's
> inc_for_reload, it appears to be missing the find_reloads_address code
> to ensure an autoinc address is reloaded entirely if it is part of a
> jump. LRA can reload just the register inside a POST_INC, which leads to
> creating an output reload.
>
> Hence, a new version of the autoinc changes, below. Since reload is
> known to work, we allow autoinc in jumps unless targetm.lra_p. One part
> of the patch is a fix for the earlier combine patch which was already
> checked in, the other part is a new version of the auto-inc-dec patch.
> Bootstrapped and tested on the gcc135 machine
> (powerpc64le-unknown-linux-gnu). OK?
Thanks :-)
Could you open a PR for the LRA problem please?
Segher