[llvm-dev] Does middle-end pass need to consider some special type when doing optimization? Or letting back-end to revert the optimization accordingly?

[Florian Hahn via llvm-dev]

> On Mar 19, 2021, at 01:58, Luo, Yuanke <yuanke.luo at intel.com> wrote:
> 
> Hi James,
>  
> Thank you for taking the time to deep dive the issue. It is very constructive. I agree we can transform “load x86_amx*” to amx load intrinsic. But it seems we need more effort to do the transform than preventing generate “load x86_amx*”. I can support transforming “load x86_amx*” to amx load intrinsic if people like this approach.
>  
> I also think Florian raise a good question. What the semantics about “load x86_amx*”. Is it different semantics than regular LLVM pointer types? What’s your opinions on it?
>  

From the points earlier, it sounds like you’d need to change `load` semantics for `x86_amx` to load blocks of data with gaps in between them? I am not sure if that’s a good idea, as there are plenty of places in LLVM that make use of that assumption I think (e.g. the code reasoning about memory locations). I’d expect lots of places would need updating and until everything is updated there will plenty of places that get this subtly wrong. This doesn’t sound scalable.

Cheers,
Florian
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