[wasm] Add narrow methods to PackedSimd

[radekdoulik]

Add them as internal as the approved API contains wrong methods for these. #53730 (comment)

This will allow faster implementation of IndexOfAnyValues for wasm. #82789 (comment)

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Issue Details

---

Add them as internal as the approved API contains wrong methods for these. #53730 (comment)

This will allow faster implementation of IndexOfAnyValues for wasm. #82789 (comment)

Author:	radekdoulik
Assignees:	radekdoulik
Labels:	area-System.Runtime.Intrinsics
Milestone:	-

[radekdoulik]

As the documentation is a bit unclear (the text and binary format parts could be explained differently about the inputs), I checked the results with this test, running with node. It looks like the inputs are indeed treated as signed integers here.

    static void TestNarrow()
    {
            System.Console.WriteLine($"IsSupported: {PackedSimd.IsSupported}");

            (var v1, var v2, var vns, var vnu) = System.TestPackedSimd.TestNarrow();

            System.Console.WriteLine($"v1: {v1} v2: {v2}");
            System.Console.WriteLine($"vns: {vns} vnu: {vnu}");

            System.Console.WriteLine("signed");
            for (int i=0; i<4; i++) {
                System.Console.WriteLine($" {v1[i],12} [{v1[i]:X8}] --> [{vns[i]:X4}] {vns[i],6}");
            }
            for (int i=0; i<4; i++) {
                System.Console.WriteLine($" {v2[i],12} [{v2[i]:X8}] --> [{vns[i+4]:X4}] {vns[i+4],6}");
            }

            System.Console.WriteLine("unsigned");
            for (int i=0; i<4; i++) {
                System.Console.WriteLine($"  {v1[i],12} [{v1[i]:X8}] --> [{vnu[i]:X4}] {vnu[i],6}");
            }
            for (int i=0; i<4; i++) {
                System.Console.WriteLine($"  {v2[i],12} [{v2[i]:X8}] --> [{vnu[i+4]:X4}] {vnu[i+4],6}");
            }
    }

    [CLSCompliant(false)]
    public partial class TestPackedSimd
    {
        private static int Next()
        {
            return System.Random.Shared.Next(0x3ffff) - 0x1ffff;
        }

        public static (Vector128<int>, Vector128<int>, Vector128<short>, Vector128<ushort>) TestNarrow()
        {
            var v1 = Vector128.Create(Next(), Next(), Next(), Next());
            var v2 = Vector128.Create(Next(), Next(), Next(), Next());

            var vns = PackedSimd.ConvertNarrowingSignedSaturate(v1, v2);
            var vnu = PackedSimd.ConvertNarrowingUnsignedSaturate(v1, v2);

            return (v1, v2, vns, vnu);
        }
    }

  IsSupported: True
  v1: <11742, -35700, -58383, 101864> v2: <83369, -3341, 95004, -111954>
  vns: <11742, -32768, -32768, 32767, 32767, -3341, 32767, -32768> vnu: <11742, 0, 0, 65535, 65535, 0, 65535, 0>
  signed
          11742 [00002DDE] --> [2DDE]  11742
         -35700 [FFFF748C] --> [8000] -32768
         -58383 [FFFF1BF1] --> [8000] -32768
         101864 [00018DE8] --> [7FFF]  32767
          83369 [000145A9] --> [7FFF]  32767
          -3341 [FFFFF2F3] --> [F2F3]  -3341
          95004 [0001731C] --> [7FFF]  32767
        -111954 [FFFE4AAE] --> [8000] -32768
  unsigned
           11742 [00002DDE] --> [2DDE]  11742
          -35700 [FFFF748C] --> [0000]      0
          -58383 [FFFF1BF1] --> [0000]      0
          101864 [00018DE8] --> [FFFF]  65535
           83369 [000145A9] --> [FFFF]  65535
           -3341 [FFFFF2F3] --> [0000]      0
           95004 [0001731C] --> [FFFF]  65535
         -111954 [FFFE4AAE] --> [0000]      0

[radekdoulik]

The relevant code from the test above:

  local.get $3
  local.get $13
  local.get $15
  i16x8.narrow.i32x4.s    [SIMD]
  v128.store offset:96 align:4    [SIMD]
  local.get $3
  local.get $13
  local.get $15
  i16x8.narrow.i32x4.u    [SIMD]
  v128.store offset:112 align:4    [SIMD]

[radekdoulik]

The failing builds are unrelated