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Sign Select instructions #124

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Sign Select instructions #124

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6 changes: 5 additions & 1 deletion proposals/simd/BinarySIMD.md
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Expand Up @@ -262,4 +262,8 @@ For example, `ImmLaneIdx16` is a byte with values in the range 0-15 (inclusive).
| `i16x8.extadd_pairwise_i8x16_s` | `TBD`| - |
| `i16x8.extadd_pairwise_i8x16_u` | `TBD`| - |
| `i32x4.extadd_pairwise_i16x8_s` | `TBD`| - |
| `i32x4.extadd_pairwise_i16x8_u` | `TBD`| - |
| `i32x4.extadd_pairwise_i16x8_u` | `TBD`| - |
| `v8x16.signselect` | `TBD`| - |
| `v16x8.signselect` | `TBD`| - |
| `v32x4.signselect` | `TBD`| - |
| `v64x2.signselect` | `TBD`| - |
4 changes: 4 additions & 0 deletions proposals/simd/ImplementationStatus.md
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Expand Up @@ -231,6 +231,10 @@
| `i16x8.extadd_pairwise_i8x16_u` | | | | | |
| `i32x4.extadd_pairwise_i16x8_s` | | | | | |
| `i32x4.extadd_pairwise_i16x8_u` | | | | | |
| `v8x16.signselect` | | | | | |
| `v16x8.signselect` | | | | | |
| `v32x4.signselect` | | | | | |
| `v64x2.signselect` | | | | | |

[1] Tip of tree LLVM as of May 20, 2020

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12 changes: 12 additions & 0 deletions proposals/simd/SIMD.md
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Expand Up @@ -683,6 +683,18 @@ Note that the normal WebAssembly `select` instruction also works with vector
types. It selects between two whole vectors controlled by a single scalar value,
rather than selecting bits controlled by a control mask vector.

### Sign select
* `v8x16.signselect(v1: v128, v2: v128, c: v128) -> v128`
* `v16x8.signselect(v1: v128, v2: v128, c: v128) -> v128`
* `v32x4.signselect(v1: v128, v2: v128, c: v128) -> v128`
* `v64x2.signselect(v1: v128, v2: v128, c: v128) -> v128`

Use the sign bits in the control mask `c` to select the corresponding element
from `v1` when 1 (negative sign) and `v2` when 0 (positive sign).

Note that these instructions work for both signed integer and floating-point
control masks.

### Lane-wise Population Count
* `i8x16.popcnt(v: v128) -> v128`

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