[FFmpeg-devel] [PATCH] arm: Consistently use proper interworking function returns

[Martin Storsjö]

On Fri, 4 Oct 2024, Martin Storsjö wrote:

> Use "bx lr", or "pop {lr}", which do proper mode switching
> between thumb and arm modes. A plain "mov pc, lr" does not switch
> from thumb mode to arm mode (while in arm mode, it does switch
> mode for a thumb caller).
>
> This is normally not an issue, as CONFIG_THUMB only is enabled if
> the C compiler defaults to thumb; but stick to patterns that can
> do mode switching if needed, for consistency.
> ---
> libswresample/arm/resample.S  | 8 ++++----
> libswscale/arm/hscale.S       | 3 +--
> libswscale/arm/output.S       | 3 +--
> libswscale/arm/yuv2rgb_neon.S | 3 +--
> 4 files changed, 7 insertions(+), 10 deletions(-)
>
> diff --git a/libswresample/arm/resample.S b/libswresample/arm/resample.S
> index 3ce7623246..791f4cc016 100644
> --- a/libswresample/arm/resample.S
> +++ b/libswresample/arm/resample.S
> @@ -30,7 +30,7 @@ function ff_resample_common_apply_filter_x4_float_neon, export=1
>     vpadd.f32           d0, d0, d1                                     @ pair adding of the 4x32-bit accumulated values
>     vpadd.f32           d0, d0, d0                                     @ pair adding of the 4x32-bit accumulator values
>     vst1.32             {d0[0]}, [r0]                                  @ write accumulator
> -    mov pc, lr
> +    bx                  lr
> endfunc

Will push.

// Martin