move{32,64}_zero_{r,v} instructions

proposals/simd/BinarySIMD.md

@@ -222,3 +222,7 @@ For example, `ImmLaneIdx16` is a byte with values in the range 0-15 (inclusive).
 | `i32x4.trunc_sat_f32x4_u`  |    `0xf9`| -                  |
 | `f32x4.convert_i32x4_s`    |    `0xfa`| -                  |
 | `f32x4.convert_i32x4_u`    |    `0xfb`| -                  |
+| `v128.move32_zero_r`       |    `0xfe`| -                  |
+| `v128.move32_zero_v`       |    `0xff`| -                  |
+| `v128.move64_zero_r`       |   `0x100`| -                  |
+| `v128.move64_zero_v`       |   `0x101`| -                  | 

proposals/simd/ImplementationStatus.md

@@ -190,6 +190,10 @@
 | `i32x4.trunc_sat_f32x4_u`  |               `-msimd128` | :heavy_check_mark: |                    |                    | :heavy_check_mark: |
 | `f32x4.convert_i32x4_s`    |               `-msimd128` | :heavy_check_mark: |                    |                    | :heavy_check_mark: |
 | `f32x4.convert_i32x4_u`    |               `-msimd128` | :heavy_check_mark: |                    |                    | :heavy_check_mark: |
+| `v128.move32_zero_r`       |                           |                                         |                    |                    |
+| `v128.move32_zero_v`       |                           |                                         |                    |                    |
+| `v128.move64_zero_r`       |                           |                                         |                    |                    |
+| `v128.move64_zero_v`       |                           |                                         |                    |                    |
 
 [1] Tip of tree LLVM as of May 20, 2020
 

proposals/simd/SIMD.md

@@ -1023,3 +1023,33 @@ def S.widen_low_T_u(a):
 def S.widen_high_T_u(a):
     return S.widen_high_T(Zext, a)
 ```
+
+
+### Move and Zero-Pad
+
+* `v128.move32_zero_r(x: i32) -> v128`
+* `v128.move32_zero_v(a: v128) -> v128`
+* `v128.move64_zero_r(x: i64) -> v128`
+* `v128.move64_zero_v(a: v128) -> v128`
+
+Move a single 32-bit or 64-bit element into the lowest bits of `v128` vector,
+and initialize all other bits of the `v128` vector to zero.
+```python
+def S.moveT_zero_r(x):
+    result = S.New()
+    for i in range(S.Lanes):
+        if i == 0:
+            result[i] = x
+        else:
+            result[i] = 0
+    return result
+
+def S.moveT_zero_v(a):
+    result = S.New()
+    for i in range(S.Lanes):
+        if i == 0:
+            result[i] = a[i]
+        else:
+            result[i] = 0
+    return result
+```