Re: [RFC PATCH 0/8] Alternative softfloat 128-bit integer support

[Daniel Henrique Barboza]

All patches but patch 01 queued in gitlab.com/danielhb/qemu/tree/ppc-next.


Thanks,


Daniel

On 3/30/22 14:59, matheus.ferst@eldorado.org.br wrote:
> From: Matheus Ferst <matheus.ferst@eldorado.org.br>
>
> This RFC is an alternative to [1] using Int128 types to implement the
> 128-bit integer conversion routines in softfloat required by the
> xscv[su]qqp and xscvqp[su]qz instructions of PowerISA v3.1.
>
> Some improvements to int128.h are made in patches 1 and 2. Patches 3-6
> implement the conversion routines, and patches 7 and 8 implement the new
> instructions.
>
> RFC: Int128 vs. pair of 64-bit values.
>   - Returning unsigned values through Int128 is not ideal, but creating
>     an "UInt128" just for this case seems excessive.
>   - OTOH, there are fewer cases to handle, especially in float->int.
>
> [1] https://lists.gnu.org/archive/html/qemu-ppc/2022-03/msg00520.html
>
> Matheus Ferst (8):
>    qemu/int128: avoid undefined behavior in int128_lshift
>    qemu/int128: add int128_urshift
>    softfloat: add uint128_to_float128
>    softfloat: add int128_to_float128
>    softfloat: add float128_to_uint128
>    softfloat: add float128_to_int128
>    target/ppc: implement xscv[su]qqp
>    target/ppc: implement xscvqp[su]qz
>
>   fpu/softfloat.c                     | 183 ++++++++++++++++++++++++++++
>   include/fpu/softfloat.h             |   7 ++
>   include/qemu/int128.h               |  25 +++-
>   target/ppc/fpu_helper.c             |  33 +++++
>   target/ppc/helper.h                 |   4 +
>   target/ppc/insn32.decode            |   7 ++
>   target/ppc/translate/vsx-impl.c.inc |  22 ++++
>   tests/unit/test-int128.c            |  32 +++++
>   8 files changed, 311 insertions(+), 2 deletions(-)