[RFC PATCH v1] arm: lib: add __gnu_thumb1_case_si

[Tony Dinh]

Hi Francis,

On Sat, Apr 1, 2023 at 2:55 PM Francis Laniel
<francis.laniel at amarulasolutions.com> wrote:
>
> The assembly for __gnu_thumb1_case_si was taken from upstream gcc and adapted
> as width suffix was removed for the add instruction [1].
>
> Signed-off-by: Francis Laniel <francis.laniel at amarulasolutions.com>
> Tested-by: Tony Dinh <mibodhi at gmail.com>
> [1] https://github.com/gcc-mirror/gcc/blob/4f181f9c7ee3efc509d185fdfda33be9018f1611/libgcc/config/arm/lib1funcs.S#L2156

Thanks for the patch! I've added Tom, Pali, and Stefan.

I think we need to do some more testing for other boards that have
CONFIG_HAS_THUMB2 and CONFIG_SPL_SYS_THUMB_BUILD. My test target
(Marvell Armada 385 SoC) is somewhat broken right now. So it will take
some time for me to get that back running to run this test.

All the best,
Tony

> ---
>  arch/arm/lib/lib1funcs.S | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>
> diff --git a/arch/arm/lib/lib1funcs.S b/arch/arm/lib/lib1funcs.S
> index 7ff4446dd6..79cedc0aad 100644
> --- a/arch/arm/lib/lib1funcs.S
> +++ b/arch/arm/lib/lib1funcs.S
> @@ -424,4 +424,21 @@ ENTRY(__gnu_thumb1_case_uhi)
>         ret     lr
>  ENDPROC(__gnu_thumb1_case_uhi)
>  .popsection
> +
> +/* Taken and adapted from: https://github.com/gcc-mirror/gcc/blob/4f181f9c7ee3efc509d185fdfda33be9018f1611/libgcc/config/arm/lib1funcs.S#L2156 */
> +.pushsection .text.__gnu_thumb1_case_si, "ax"
> +ENTRY(__gnu_thumb1_case_si)
> +       push    {r0, r1}
> +       mov     r1, lr
> +       adds    r1, r1, #2      /* Align to word.  */
> +       lsrs    r1, r1, #2
> +       lsls    r0, r0, #2
> +       lsls    r1, r1, #2
> +       ldr     r0, [r1, r0]
> +       adds    r0, r0, r1
> +       mov     lr, r0
> +       pop     {r0, r1}
> +       mov     pc, lr          /* We know we were called from thumb code.  */
> +ENDPROC(__gnu_thumb1_case_si)
> +.popsection
>  #endif
> --
> 2.34.1
>