This is a tracking issue for a post-MVP feature
It will be updated as the issue progresses.

Topic Fixed-width SIMD
Champion @PeterJensen, @arunetm
Status in progress
Phase Feature proposal
Linked issues #148, #41
Linked repositories github.com/WebAssembly/simd

Details

Support fixed-width SIMD vectors, initially only for 128-bit wide vectors as demonstrated in PNaCl's SIMD and SIMD.js.

SIMD adds new local types (e.g., f32x4) so it has to be part of the core semantics. SIMD operators (e.g., f32x4.add) could be either builtin operators (no different from i32.add) or exports of a builtin SIMD module.