Re: Smstateen for Zcmt


John Hauser
 

Mark wrote:
Please explain to me why we would not want implementers to implement Zc*
and not C. I am not sure I understand the use cases and workloads well. Am
I misunderstanding?
We expect people to implement the new Zcm* extensions together with Zca
and Zcb. Zca is the subset of C that drops the compressed instructions
for double-precision floating-point loads and stores. The expectation
is that most embedded systems will find the new compressed instructions
more useful than the existing ones for double-precision floating-point,
especially as smaller embedded systems typically don't do double-
precision floating-point at all. But even for those that do, they can
still have the standard non-compressed D instructions together with Zca
+ Zcb + all of Zcm*.

I understand that implementers want to pick and choose in embedded
environments but I'd think we'd want the ability to have them all
available together.
The total number of 16-bit encodings is too small to contain everything
we might want to put in that space. Choices must be made.

- John Hauser

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