Floating-point rounding instructions

SIMD equivalents of the nearest/trunc/ceil/floor instructions

Author: Maratyszcza

proposals/simd/BinarySIMD.md

@@ -202,3 +202,11 @@ The `v8x16.shuffle` instruction has 16 bytes after `simdop`.
 | `i8x16.abs`                |    `0xe1`| -                  |
 | `i16x8.abs`                |    `0xe2`| -                  |
 | `i32x4.abs`                |    `0xe3`| -                  |
+| `f32x4.nearest`            |    `0xe4`| -                  |
+| `f32x4.trunc`              |    `0xe5`| -                  |
+| `f32x4.ceil`               |    `0xe6`| -                  |
+| `f32x4.floor`              |    `0xe7`| -                  |
+| `f64x2.nearest`            |    `0xe8`| -                  |
+| `f64x2.trunc`              |    `0xe9`| -                  |
+| `f64x2.ceil`               |    `0xea`| -                  |
+| `f64x2.floor`              |    `0xeb`| -                  |

proposals/simd/ImplementationStatus.md

@@ -142,6 +142,10 @@
 | `f32x4.div`                |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | `f32x4.min`                |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | `f32x4.max`                |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
+| `f32x4.nearest`            |                           |                       |                    |                    |
+| `f32x4.trunc`              |                           |                       |                    |                    |
+| `f32x4.ceil`               |                           |                       |                    |                    |
+| `f32x4.floor`              |                           |                       |                    |                    |
 | `f64x2.abs`                |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | `f64x2.neg`                |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | `f64x2.sqrt`               |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
@@ -151,6 +155,10 @@
 | `f64x2.div`                |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | `f64x2.min`                |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | `f64x2.max`                |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
+| `f64x2.nearest`            |                           |                       |                    |                    |
+| `f64x2.trunc`              |                           |                       |                    |                    |
+| `f64x2.ceil`               |                           |                       |                    |                    |
+| `f64x2.floor`              |                           |                       |                    |                    |
 | `i32x4.trunc_sat_f32x4_s`  |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | `i32x4.trunc_sat_f32x4_u`  |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | `f32x4.convert_i32x4_s`    |               `-msimd128` |    :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |

proposals/simd/SIMD.md

@@ -882,6 +882,30 @@ Lane-wise IEEE `multiplication`.
 
 Lane-wise IEEE `squareRoot`.
 
+### Round to nearest integer
+* `f32x4.nearest(a: v128) -> v128`
+* `f64x2.nearest(a: v128) -> v128`
+
+Lane-wise rounding to the nearest integral value; if two values are equally near, rounds to the even one.
+
+### Round to integer toward zero (truncate to integer)
+* `f32x4.trunc(a: v128) -> v128`
+* `f64x2.trunc(a: v128) -> v128`
+
+Lane-wise rounding to the nearest integral value with the magniture not larger than the input.
+
+### Round to integer above (ceiling)
+* `f32x4.ceil(a: v128) -> v128`
+* `f64x2.ceil(a: v128) -> v128`
+
+Lane-wise rounding to the nearest integral value not smaller than the input.
+
+### Round to integer below (floor)
+* `f32x4.floor(a: v128) -> v128`
+* `f64x2.floor(a: v128) -> v128`
+
+Lane-wise rounding to the nearest integral value not greater than the input.
+
 ## Conversions
 ### Integer to floating point
 * `f32x4.convert_i32x4_s(a: v128) -> v128`