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fraunhoferhhi / vvenc

VVenC, the Fraunhofer Versatile Video Encoder
https://www.hhi.fraunhofer.de/en/departments/vca/technologies-and-solutions/h266-vvc.html
BSD 3-Clause Clear License
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Fix compilation for 32-bit Arm platforms #453

Closed georges-arm closed 1 month ago

georges-arm commented 1 month ago

The existing Neon code makes use of some intrinsics which are only available on AArch64, so adjust these implementations to also work on Armv7 platforms.

Also introduce a new REAL_TARGET_AARCH64 macro to distinguish between 32-bit and 64-bit in new and existing Arm code.

Since these implementations require that Neon is available, also add -mfpu=neon to the compile line for these files. This necessitates removing the SIMD implementation files from LTO in the same way that is already done for the x86 kernels.

georges-arm commented 1 month ago

I'm not really sure what the current intended interaction with is between enabling SIMD since we have both VVENC_ENABLE_X86_SIMD and VVENC_ENABLE_ARM_SIMD which can technically be enabled independently of each other. I don't think all combinations of this currently compile but also not sure if it is something we are interested in supporting. This seems slightly orthogonal to the existing 32-bit compilation issues so I've not tried to solve it here, but interested in hearing what you think is the best approach to take here?

K-os commented 1 month ago

Thanks for incorporating my suggestions. From your code around enabling SVE/SVE2 I assume these extensions are not available for ARMv7 ? Then I think the split between ARM and AARCH64 for VVENC_TARGET_ARCH really makes sense.

Concerning the interaction between VVENC_ENABLE_X86_SIMD and VVENC_ENABLE_ARM_SIMD, my intention was that all combinations are possible. I know it worked at some point in time, but I am not sure about the current status. I will look into it, when your changes are merged.

georges-arm commented 1 month ago

Thanks for incorporating my suggestions. From your code around enabling SVE/SVE2 I assume these extensions are not available for ARMv7 ?

Your interpretation is correct. Both SVE and SVE2 are only available in the 64-bit architecture (available from Armv8.2-A and Armv9.0-A respectively).

adamjw24 commented 1 month ago

Thanks for the MR @georges-arm and for the review @K-os

georges-arm commented 4 weeks ago

Concerning the interaction between VVENC_ENABLE_X86_SIMD and VVENC_ENABLE_ARM_SIMD, my intention was that all combinations are possible. I know it worked at some point in time, but I am not sure about the current status. I will look into it, when your changes are merged.

This should be fixed by #455. Thanks for confirming the intent here.