[FP16] Implement madd and nmadd. (#6878)

Specified at
https://github.com/WebAssembly/half-precision/blob/main/proposals/half-precision/Overview.md

A few notes:
- The F32x4 and F64x2 versions of madd and nmadd are missing spect
tests.
- For madd, the implementation was incorrectly doing `(b*c)+a` where it
should be `(a*b)+c`.
- For nmadd, the implementation was incorrectly doing `(-b*c)+a` where
it should be `-(a*b)+c`.
- There doesn't appear to be a great way to actually implement a fused
nmadd, but the spec allows the double rounded version I added.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/wasm.h b/src/wasm.h
index 86ee12972..a7ad6ec6c 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -574,6 +574,8 @@ enum SIMDTernaryOp {
   Bitselect,
 
   // Relaxed SIMD
+  RelaxedMaddVecF16x8,
+  RelaxedNmaddVecF16x8,
   RelaxedMaddVecF32x4,
   RelaxedNmaddVecF32x4,
   RelaxedMaddVecF64x2,