[FFmpeg-devel] [PATCH 3/3] avcodec/hevc: Add wasm simd128 idct

[Rémi Denis-Courmont]

Le 13 novembre 2024 16:16:36 GMT+02:00, Zhao Zhili <quinkblack at foxmail.com> a écrit :
>From: Zhao Zhili <zhilizhao at tencent.com>
>
>We don't use intrinsics normally for performance reasons. However,
>WASM isn't machine instruction.

I don't think that's relevant to the matter.

What may be relevant is that WASM is an infinite register ISA, so that the compiler's register allocator will never run out and spill.

But then again, it will have to be recompiled to a finite register machine ISA, with probably 8, 16 or 32 vector registers, and if we break whatever the machine's limit is, performance will suck.

So I actually expect that assembler will be about as relevant for WASM as it is for the machine ISA with the fewest vector registers... on that architecture.

But in any case, I cannot agree with that unsubstantiated statement. Unless proven otherwise, assembler is relevant here too.