Deepti Gandluri

@zeux In V8, we could trace the origin, but most Wasm engines by design are more simplistic than that, i.e. the operations are expected to map directly to code generation...

@zeux I agree that we don't need a spec change here, but not necessarily for the same reasons. My earlier comment was trying to clarify that there were some speculative...

I think I misunderstood the point you're trying to make with tracking the origin - tracking constantness, and tracking the origin to me mean different things. Deducing that the origin...

@zeux I think you could do both, it's a higher level optimization that we disable for Wasm codegen because in general Wasm operations should map very closely to native instructions....

@abrown Is there more that you were looking for here, or can this be closed?

I don't see a problem with this, also I think we already catch this as a validation failure in the V8 implementation even though it's not clearly specified here, as...

The shifts were included as these are useful operations, narrow shifts in the initial version for codecs, and 64x2 shifts with benchmarking results from @ngzhian. The codegen on Intel hardware...

> @dtig, we captured in the notes that there are some uses of 8x16 shifts in vp8 code. Looking at https://github.com/webmproject/libvpx, I see some uses of 8x16 shifts in the...

Thanks @abrown for initiating offline conversations and adding numbers. @zeux makes a good point that the performance cliff in practice is not expected to be this large. I've mentioned this...

Thanks for drafting this, I would like to suggest one edit to the third point. Instead of "How widely supported are the instructions? Are there single instruction lowering on all...