[Libre-soc-bugs] [Bug 713] PartitionedSignal enhancement to add partition-context-aware lengths

bugzilla-daemon at libre-soc.org bugzilla-daemon at libre-soc.org
Wed Oct 6 20:32:19 BST 2021


--- Comment #17 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
(In reply to Jacob Lifshay from comment #15)
> (In reply to Luke Kenneth Casson Leighton from comment #13)
> > (In reply to Jacob Lifshay from comment #11)
> > 
> > > assuming a layout of:
> > > SimdLayout({
> > >     1: unsigned(10),
> > >     2: unsigned(12),
> > >     4: unsigned(15),
> > > })
> > 
> > noooo, different types of signedness down at the lane level is
> > completely out of the question.
> Actually, SimdLayout specifically asserts that all lanes have the same
> signedness, essentially it's just there to make passing in Shapes easy, and
> because, conceptually, it's the lanes who's shape we care about, the whole
> signal could be signed/unsigned/whatever it doesn't matter as long as the
> lanes behave as expected.

jacob: PartitionedSignal does not comprehend lane-based independent signs
or types.  none of the submodules know about it.

there is *one* internal Signal which is given the shape at the max bitwidth
required and its sign and that's it.

adding anything else on top of that is too much.

the requirements here are very very simple, this is an enhancement we are
discussing which cannot disrupt the existing code and has to be minimal and
ultra quick and simple to implement.

you could have written the functions by now, they are far shorter than
the text that you have typed *resisting* the path that i am trying to
illustrate to you and the important insight i would like to share.

if i am forced to do the code myself you will in no way have
the same insight and understanding.

please: can you write the two functions, they should
take you only about 20 minutes absolute max.

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