Re: [PATCH v3 0/2] RISC-V psABI: Assign DWARF register numbers to vector registers

[Palmer Dabbelt <palmer@dabbelt.com>]

On Sun, 02 Oct 2022 08:58:56 PDT (-0700), binutils@sourceware.org wrote:
>
> On 10/1/22 14:27, Andrew Burgess via Binutils wrote:
>> Tsukasa OI via Binutils <binutils@sourceware.org> writes:
>>
>>> Hello,
>>>
>>> Surprisingly, I found that no vector registers (v0-v31) are assigned DWARF
>>> register numbers.  RISC-V ABIs Specification (riscv-elf-psabi-doc) is not
>>> ratified yet but at least frozen.  So, I consider it's stable to upstream
>>> it.  According to the documentation, it has register numbers 96 (v0) -
>>> 127 (v31).
>>>
>>> [Changes: v1 -> v2]
>>> Remove invented word "VPRs" (at least it has no consistent uses in the
>>> RISC-V ecosystem) and replaced with "Vector registers"
>>>
>>> [Changes: v2 -> v3]
>>> Changed reference (v1.0-rc3 -> v1.0-rc4).
>>>
>>> Tracker on GitHub:
>>> <https://github.com/a4lg/binutils-gdb/wiki/riscv_psabi_dwarf_vector_regs>
>>>
>>> RISC-V ABIs Specification Version 1.0-rc4: Frozen
>>> <https://github.com/riscv-non-isa/riscv-elf-psabi-doc/releases/tag/v1.0-rc4>
>>>
>>>
>>> I also added DWARF register number tests not just for CSRs (existing) and
>>> vector registers (I just added), but also for GPRs (0-31) and FPRs
>>> (32-63).
>> Hi Tsukasa,
>>
>> I can't approve binutils patches, but as this mentioned RISC-V and
>> DWARF, both of which I'm interested in, I took a look :)
>>
>> Both these patches look good to me.  The register numbers align with the
>> spec, and the test makes sense.
>
> Well, that's the key property -- they align with the spec.

My worry here was the PDF not aligining with the implementation, but I 
think I'd just been mis-reading the sources: I'd seen

  RISCV_PRIV_REGNUM = 4161,
  RISCV_V0_REGNUM,

but hadn't realized that I should actually be looking at

  RISCV_DWARF_REGNUM_V0 = 96,

so this is OK (and it looks like GCC is correct as well).

Thanks!

> I'm also not sure if I can approve for binutils, but if I can, OK for
> the trunk ;-)
>
> Jeff