[Libre-soc-dev] Wishbone and House Contract Of Sale Proposition

[lkcl]

On October 28, 2021 6:32:04 PM UTC, Andrey Miroshnikov <andrey at technepisteme.xyz> wrote:

>As for speculative execution, I'm not too knowledgable as to why the 
>queue is dropped. I think of it as a failed branch-prediction, where
>the 
>cpu pipe-line would have to be flushed, 

yes.  so for in-order, you think of the pipeline as being a one-to-one direct preservation of the issue order.

but... why would an OoO be any different??

it wouldn't, would it?

therefore, the Shadow system still has to preserve the issue order, doesn't it?

and, so, despite the data structure not being one-to-one "a pipeline", the cancellation still has to drop everything that was issued *after* the exception /branch-predict-fail.


>except in this case the 
>Shadowing principle is more generalised than branch-prediction.

yes.


>As mentioned by Luke in IRC 
>(https://libre-soc.org/irclog/%23libre-soc.2021-10-28.log.html):
>'''
>Shadowing can be used for
>Branch Prediction
>Speculative Execution
>Predication
>Memory "Total Store Order" preservation
>Cache access resolution
>'''
>
>
>Andrey
>
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