[Libre-soc-bugs] [Bug 231] Video Opcodes Standards writeup

bugzilla-daemon at libre-soc.org bugzilla-daemon at libre-soc.org
Wed Sep 2 20:42:43 BST 2020


Jacob Lifshay <programmerjake at gmail.com> changed:

           What    |Removed                     |Added
                 CC|                            |programmerjake at gmail.com

--- Comment #5 from Jacob Lifshay <programmerjake at gmail.com> ---
(In reply to Cole Poirier from comment #4)
> I know Jacob has an idea for at least one instruction, something to do with
> triangle vertex extraction into a vector(?), Jacob, please correct my flawed
> memory of what you relayed to me last week.

I was thinking of instructions to help with computing which pixels are inside a
triangle for rendering purposes. That's generally conceptually split into two
categories that overlap somewhat: triangle setup and rasterization.

> I think using pia to see what the most common operations executed by popular
> video compression algorithms would be one of the analyses we should do so
> that it can help inform our instruction addition evaluation. I may be
> severely misunderstanding some things here, but hey, that'll be good for
> both me and future readers of the bugs ;)

power-instruction-analyzer as it is currently is not suitable for that, since
it has instruction models for single instructions and checks to see if they
match the behavior of the inline-assembler versions of those instructions. It
does not allow running arbitrary programs.

Something like gdb (on a power processor) or qemu (on any supported host ISA)
would be better for that, since those are designed to actually run a program
given to them. It would have to be set up to step instruction by instruction
and disassemble at each step, incrementing counters for each instruction kind.
Other good options would be something like a profiler, they are specifically
designed to measure how often instructions/code pieces are run.

objdump or just compiling the program's source to assembly would also be useful
(to a lesser extent), since you can see which instructions the program

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