Re: PING: [ARM] Model automodified addresses in the Cortex A8 and A9 schedulers -- NEON

[Ramana Radhakrishnan <ramana dot radhakrishnan at linaro dot org>]

On 9 September 2011 13:56, Richard Sandiford
<richard.sandiford@linaro.org> wrote:
> Ping for this patch:

>> This is the NEON part of the patch to handle address register writeback
>> in the Cortex A8 and A9 schedulers.  Although I can find no documentation
>> to say exactly how this is handled by the pipelines, a latency of 1
>> does seem to work well in practice, and is much easier to implement.

It sounds like this is good enough in practice.

>
> ? ?http://gcc.gnu.org/ml/gcc-patches/2011-08/msg01488.html
>
> which models address register writeback in the Cortex A8 and A9 NEON
> schedulers. ?(Ramana has already approved the core equivalent, thanks.)

I do have a one nit on the ml bit though I must say I'm not an ML
expert which is why I resisted for a while. The one comment that I
have and I should have realized earlier was that the file had been
parameterized by the core in quite a few places and I would like to
still retain that capability.

This look better ? I have retained your original logic and only
parameterized wblatency on the core .

Thoughts ? Can someone else also give the ML bits a once-over ?  It
appears to generate identical descriptions to yours.

cheers
Ramana

gcc/
	* config/arm/neon-schedgen.ml (guard): Add Guard_writeback and
	Guard_writeback_only.
	(writebackLatency): New function.
	(collate_bypasses): Split hashtable insertion into a separate
	function.  Add address writeback dependencies for load-store
	instructions.  Use writebackLatency. Sort bypasses in order of
decreasing latency.
	(guard_fn): Handle Guard_writeback and Guard_writeback_only.
	* config/arm/cortex-a8-neon.md: Regenerated.
	* config/arm/cortex-a9-neon.md: Likewise.

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