Hi Sam, As Wasm only supports Simd128, the Simd256 operations are part of an experimental (work-in-progress) implementation developed by Intel. The progress is tracked here: https://crbug.com/42202660 The build flag is controlled here: https://source.chromium.org/chromium/chromium/src/+/main:v8/BUILD.gn;l=681;drc=9be9b0197a97a1f661c4cbf7b354c21ec3fcbe7f When the build flag is set, it can be enabled with the flag --experimental-wasm-revectorize.
I don't think the current implementation tries to go further than 256 bit vector widths. Cheers, Matthias On Fri, Oct 25, 2024 at 1:23 PM Sam Parker-Haynes <[email protected]> wrote: > Hi, > > I'm looking a lot at shuffles, in turboshaft, and thinking about how we > can generate de-interleaving loads. For AArch64 we have the LD1, LD2, LD3 > and LD4 instructions which can load in a maximum of 4x128-bit values. > > To simplify my life, I'm currently only considering LD2, which will load > 2x128-bits, so I figure I the existing Simd256 operations would be good for > this. But these are all currently predicated > on V8_ENABLE_WASM_SIMD256_REVEC, do they have to be..? > > I only want to support wide vectors for loads, using Simd256Extract128Lane > to produce usable values for arithmetic, etc... but are there any parts of > the pipeline that make assumptions when 'revec' is enabled that will make > life hard? > > And when trying to support LD3 (3x128-bit) and LD4 (4x128-bit), would this > approach still scale? > > Thanks, > Sam > > -- > -- > v8-dev mailing list > [email protected] > http://groups.google.com/group/v8-dev > --- > You received this message because you are subscribed to the Google Groups > "v8-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/v8-dev/5a86a10c-4b95-4dcb-b7b1-efce05865b97n%40googlegroups.com > <https://groups.google.com/d/msgid/v8-dev/5a86a10c-4b95-4dcb-b7b1-efce05865b97n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- -- v8-dev mailing list [email protected] http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/v8-dev/CACx9iAN%3DVhJTUNh8-MF3NsyN1nnqpUnrb7b4vCVUZ3jZZLen0g%40mail.gmail.com.
