llvm dev - Jan 2022 - Public review for RISC-V psABI v1.0-rc1

Hi all:

It’s Kito Cheng from the RISC-V community, Jessica Clarke and I are
working on releasing a stable version of the psABI, and are seeking
feedback from the open source community.

The goal of this stable release is having a stable version to let
people use as a reference point. We are trying to describe what we did
and what we have, and with as little new stuff as necessary for the
new and upcoming extensions.

But that does NOT mean we won’t accept any new stuff in the future,
the RISC-V psABI will still accept new backwards-compatible changes
and release periodically going forwards.

Feel free to give feedback or ask any question by replying to this
mail or creating an issue on GitHub!

Document:
https://github.com/riscv-non-isa/riscv-elf-psabi-doc/releases/tag/v1.0-rc1
Create issues here: https://github.com/riscv-non-isa/riscv-elf-psabi-doc/issues

My 2c:
1. XLEN should be defined somewhere for the sake of completeness. The first
occurrence of this word happens in "Integer Calling Convention" and
the
reader has no clue of what it means. If the reader is supposed to read some
other manual (e.g. ISA manual) then it should be mentioned in a new
prerequisites section.

2. I feel the allocation of aggregates to registers/stack needs to be
explained in detail in "Integer Register Convention". Specifically,
"if only one register is available, the first half is passed in a register
and the second half is passed on the stack."
a. How is the first "half" supposed to be calculated? Size of an
aggregate
need not be an even value.
b. As one iterates over the fields of the aggregate, the fields will get
allocated to the bits in the available register. What if at a given field
there is no space in the current register? Would ABI allocate the field to
the next register?

3. Isn't there a need to standardize stack frame layout?






On Sun, Jan 9, 2022 at 3:36 PM Kito Cheng via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hi all:
>
> It’s Kito Cheng from the RISC-V community, Jessica Clarke and I are
> working on releasing a stable version of the psABI, and are seeking
> feedback from the open source community.
>
> The goal of this stable release is having a stable version to let
> people use as a reference point. We are trying to describe what we did
> and what we have, and with as little new stuff as necessary for the
> new and upcoming extensions.
>
> But that does NOT mean we won’t accept any new stuff in the future,
> the RISC-V psABI will still accept new backwards-compatible changes
> and release periodically going forwards.
>
> Feel free to give feedback or ask any question by replying to this
> mail or creating an issue on GitHub!
>
> Document:
> https://github.com/riscv-non-isa/riscv-elf-psabi-doc/releases/tag/v1.0-rc1
> Create issues here:
> https://github.com/riscv-non-isa/riscv-elf-psabi-doc/issues
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20220109/8e47dfbb/attachment.html>