[trimmer] per-RID linked corlib assembly contains foreign platform intrinsics classes

[grendello]

This happens on xamarin-android/main (.NET8), but I suppose it will apply to other platforms as well.

I noticed that System.Private.CoreLib.dll output by the linker for arm64 RID contains X86 and WASM intrinsics types:

549: System.Runtime.Intrinsics.Wasm.PackedSimd (flist=2253, mlist=6116, flags=0x100081, extends=0xa0)
554: System.Runtime.Intrinsics.X86.X86Base (flist=2253, mlist=6151, flags=0x100081, extends=0xa0)
555: System.Runtime.Intrinsics.X86.Sse (flist=2253, mlist=6151, flags=0x100081, extends=0x8a8)
556: System.Runtime.Intrinsics.X86.Sse2 (flist=2253, mlist=6151, flags=0x100081, extends=0x8ac)
557: System.Runtime.Intrinsics.X86.Sse3 (flist=2253, mlist=6154, flags=0x100081, extends=0x8b0)
558: System.Runtime.Intrinsics.X86.Sse41 (flist=2253, mlist=6154, flags=0x100081, extends=0x8bc)
559: System.Runtime.Intrinsics.X86.Ssse3 (flist=2253, mlist=6155, flags=0x100081, extends=0x8b4)

It appears some of the x86 classes are removed, but not all. For comparison, this is a list of types from the same assembly but linked for x84:

558: System.Runtime.Intrinsics.X86.X86Base (flist=2255, mlist=6330, flags=0x100081, extends=0xa0)
559: System.Runtime.Intrinsics.X86.X86Base/X64 (flist=2255, mlist=6333, flags=0x100082, extends=0xa0)
560: System.Runtime.Intrinsics.X86.Avx (flist=2255, mlist=6336, flags=0x100081, extends=0x90c)
561: System.Runtime.Intrinsics.X86.Avx2 (flist=2255, mlist=6338, flags=0x100081, extends=0x8c0)
562: System.Runtime.Intrinsics.X86.Avx512BW (flist=2255, mlist=6344, flags=0x100081, extends=0x8cc)
563: System.Runtime.Intrinsics.X86.Avx512F (flist=2255, mlist=6346, flags=0x100081, extends=0x8c4)
564: System.Runtime.Intrinsics.X86.Bmi1 (flist=2255, mlist=6347, flags=0x100081, extends=0x8b8)
565: System.Runtime.Intrinsics.X86.Bmi1/X64 (flist=2255, mlist=6349, flags=0x100082, extends=0x8bc)
566: System.Runtime.Intrinsics.X86.Bmi2 (flist=2255, mlist=6352, flags=0x100081, extends=0x8b8)
567: System.Runtime.Intrinsics.X86.Bmi2/X64 (flist=2255, mlist=6352, flags=0x100082, extends=0x8bc)
568: System.Runtime.Intrinsics.X86.Lzcnt (flist=2255, mlist=6354, flags=0x100081, extends=0x8b8)
569: System.Runtime.Intrinsics.X86.Lzcnt/X64 (flist=2255, mlist=6356, flags=0x100082, extends=0x8bc)
570: System.Runtime.Intrinsics.X86.Popcnt (flist=2255, mlist=6358, flags=0x100081, extends=0x90c)
571: System.Runtime.Intrinsics.X86.Sse (flist=2255, mlist=6360, flags=0x100081, extends=0x8b8)
572: System.Runtime.Intrinsics.X86.Sse/X64 (flist=2255, mlist=6360, flags=0x100082, extends=0x8bc)
573: System.Runtime.Intrinsics.X86.Sse2 (flist=2255, mlist=6360, flags=0x100081, extends=0x8ec)
574: System.Runtime.Intrinsics.X86.Sse2/X64 (flist=2255, mlist=6373, flags=0x100082, extends=0x8f0)
575: System.Runtime.Intrinsics.X86.Sse3 (flist=2255, mlist=6376, flags=0x100081, extends=0x8f4)
576: System.Runtime.Intrinsics.X86.Sse3/X64 (flist=2255, mlist=6376, flags=0x100082, extends=0x8f8)
577: System.Runtime.Intrinsics.X86.Sse41 (flist=2255, mlist=6376, flags=0x100081, extends=0x910)
578: System.Runtime.Intrinsics.X86.Sse41/X64 (flist=2255, mlist=6379, flags=0x100082, extends=0x914)
579: System.Runtime.Intrinsics.X86.Sse42 (flist=2255, mlist=6380, flags=0x100081, extends=0x904)
580: System.Runtime.Intrinsics.X86.Ssse3 (flist=2255, mlist=6380, flags=0x100081, extends=0x8fc)
581: System.Runtime.Intrinsics.X86.Ssse3/X64 (flist=2255, mlist=6382, flags=0x100082, extends=0x900)

The x64 version also contains some ARM intrinsics, but not all:

553: System.Runtime.Intrinsics.Wasm.PackedSimd (flist=2255, mlist=6322, flags=0x100081, extends=0xa0)
554: System.Runtime.Intrinsics.Arm.AdvSimd (flist=2255, mlist=6325, flags=0x100081, extends=0x8b0)
555: System.Runtime.Intrinsics.Arm.AdvSimd/Arm64 (flist=2255, mlist=6326, flags=0x100082, extends=0x8b4)
556: System.Runtime.Intrinsics.Arm.ArmBase (flist=2255, mlist=6330, flags=0x100081, extends=0xa0)
557: System.Runtime.Intrinsics.Arm.ArmBase/Arm64 (flist=2255, mlist=6330, flags=0x100082, extends=0xa0)

Would it be possible to remove all of them? They are essentially dead weight for the target RID.

Attached is a zip with both assemblies mentioned above. The app being built was the dotnet new android template for NET8
corlib.zip

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Issue Details

---

This happens on xamarin-android/main (.NET8), but I suppose it will apply to other platforms as well.

I noticed that System.Private.CoreLib.dll output by the linker for arm64 RID contains X86 and WASM intrinsics types:

549: System.Runtime.Intrinsics.Wasm.PackedSimd (flist=2253, mlist=6116, flags=0x100081, extends=0xa0)
554: System.Runtime.Intrinsics.X86.X86Base (flist=2253, mlist=6151, flags=0x100081, extends=0xa0)
555: System.Runtime.Intrinsics.X86.Sse (flist=2253, mlist=6151, flags=0x100081, extends=0x8a8)
556: System.Runtime.Intrinsics.X86.Sse2 (flist=2253, mlist=6151, flags=0x100081, extends=0x8ac)
557: System.Runtime.Intrinsics.X86.Sse3 (flist=2253, mlist=6154, flags=0x100081, extends=0x8b0)
558: System.Runtime.Intrinsics.X86.Sse41 (flist=2253, mlist=6154, flags=0x100081, extends=0x8bc)
559: System.Runtime.Intrinsics.X86.Ssse3 (flist=2253, mlist=6155, flags=0x100081, extends=0x8b4)

It appears some of the x86 classes are removed, but not all. For comparison, this is a list of types from the same assembly but linked for x84:

558: System.Runtime.Intrinsics.X86.X86Base (flist=2255, mlist=6330, flags=0x100081, extends=0xa0)
559: System.Runtime.Intrinsics.X86.X86Base/X64 (flist=2255, mlist=6333, flags=0x100082, extends=0xa0)
560: System.Runtime.Intrinsics.X86.Avx (flist=2255, mlist=6336, flags=0x100081, extends=0x90c)
561: System.Runtime.Intrinsics.X86.Avx2 (flist=2255, mlist=6338, flags=0x100081, extends=0x8c0)
562: System.Runtime.Intrinsics.X86.Avx512BW (flist=2255, mlist=6344, flags=0x100081, extends=0x8cc)
563: System.Runtime.Intrinsics.X86.Avx512F (flist=2255, mlist=6346, flags=0x100081, extends=0x8c4)
564: System.Runtime.Intrinsics.X86.Bmi1 (flist=2255, mlist=6347, flags=0x100081, extends=0x8b8)
565: System.Runtime.Intrinsics.X86.Bmi1/X64 (flist=2255, mlist=6349, flags=0x100082, extends=0x8bc)
566: System.Runtime.Intrinsics.X86.Bmi2 (flist=2255, mlist=6352, flags=0x100081, extends=0x8b8)
567: System.Runtime.Intrinsics.X86.Bmi2/X64 (flist=2255, mlist=6352, flags=0x100082, extends=0x8bc)
568: System.Runtime.Intrinsics.X86.Lzcnt (flist=2255, mlist=6354, flags=0x100081, extends=0x8b8)
569: System.Runtime.Intrinsics.X86.Lzcnt/X64 (flist=2255, mlist=6356, flags=0x100082, extends=0x8bc)
570: System.Runtime.Intrinsics.X86.Popcnt (flist=2255, mlist=6358, flags=0x100081, extends=0x90c)
571: System.Runtime.Intrinsics.X86.Sse (flist=2255, mlist=6360, flags=0x100081, extends=0x8b8)
572: System.Runtime.Intrinsics.X86.Sse/X64 (flist=2255, mlist=6360, flags=0x100082, extends=0x8bc)
573: System.Runtime.Intrinsics.X86.Sse2 (flist=2255, mlist=6360, flags=0x100081, extends=0x8ec)
574: System.Runtime.Intrinsics.X86.Sse2/X64 (flist=2255, mlist=6373, flags=0x100082, extends=0x8f0)
575: System.Runtime.Intrinsics.X86.Sse3 (flist=2255, mlist=6376, flags=0x100081, extends=0x8f4)
576: System.Runtime.Intrinsics.X86.Sse3/X64 (flist=2255, mlist=6376, flags=0x100082, extends=0x8f8)
577: System.Runtime.Intrinsics.X86.Sse41 (flist=2255, mlist=6376, flags=0x100081, extends=0x910)
578: System.Runtime.Intrinsics.X86.Sse41/X64 (flist=2255, mlist=6379, flags=0x100082, extends=0x914)
579: System.Runtime.Intrinsics.X86.Sse42 (flist=2255, mlist=6380, flags=0x100081, extends=0x904)
580: System.Runtime.Intrinsics.X86.Ssse3 (flist=2255, mlist=6380, flags=0x100081, extends=0x8fc)
581: System.Runtime.Intrinsics.X86.Ssse3/X64 (flist=2255, mlist=6382, flags=0x100082, extends=0x900)

The x64 version also contains some ARM intrinsics, but not all:

553: System.Runtime.Intrinsics.Wasm.PackedSimd (flist=2255, mlist=6322, flags=0x100081, extends=0xa0)
554: System.Runtime.Intrinsics.Arm.AdvSimd (flist=2255, mlist=6325, flags=0x100081, extends=0x8b0)
555: System.Runtime.Intrinsics.Arm.AdvSimd/Arm64 (flist=2255, mlist=6326, flags=0x100082, extends=0x8b4)
556: System.Runtime.Intrinsics.Arm.ArmBase (flist=2255, mlist=6330, flags=0x100081, extends=0xa0)
557: System.Runtime.Intrinsics.Arm.ArmBase/Arm64 (flist=2255, mlist=6330, flags=0x100082, extends=0xa0)

Would it be possible to remove all of them? They are essentially dead weight for the target RID.

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

[akoeplinger]

They're basically preserved because of this reference:

This is coming from here:

runtime/src/libraries/System.Private.CoreLib/src/System/Text/Unicode/Utf8Utility.Transcoding.cs

Lines 969 to 978 in f20509b

	else
	{
	if (!Sse41.TestZ(utf16Data, nonAsciiUtf16DataMask))
	{
	goto LoopTerminatedDueToNonAsciiDataInVectorLocal;
	}
	// narrow and write
	Sse2.StoreScalar((ulong*)pOutputBuffer /* unaligned */, Sse2.PackUnsignedSaturate(utf16Data, utf16Data).AsUInt64());
	}

I'm assuming the linker isn't able to figure out that this else is not possible, I think we could add else if (Sse41.X64.IsSupported) instead there.

[grendello]

I noticed the following after disassembling the linker binary:

.method /*06000800*/ private hidebysig static 
          valuetype System.ValueTuple`3/*02000105*/<valuetype System.Runtime.Intrinsics.Vector128`1/*02000220*/<uint8>,valuetype System.Runtime.Intrinsics.Vector128`1/*02000220*/<uint8>,valuetype System.Runtime.Intrinsics.Vector128`1/*02000220*/<uint8>> 
          FormatGuidVector128Utf8(valuetype System.Guid/*02000096*/ A_0,
                                  bool A_1) cil managed aggressiveinlining
  // SIG: 00 02 15 11 84 14 03 15 11 88 80 01 05 15 11 88 80 01 05 15 11 88 80 01 05 11 82 58 02
  {
    .custom /*0C0001CD:06001894*/ instance void System.Runtime.CompilerServices.CompExactlyDependsOnAttribute/*02000255*/::.ctor(class System.Type/*02000038*/) /* 06001894 */ = ( 01 00 23 53 79 73 74 65 6D 2E 52 75 6E 74 69 6D   // ..#System.Runtim
                                                                                                                                                                                   65 2E 49 6E 74 72 69 6E 73 69 63 73 2E 58 38 36   // e.Intrinsics.X86
                                                                                                                                                                                   2E 53 73 73 65 33 00 00 )                         // .Ssse3..
    .custom /*0C0001CE:06001894*/ instance void System.Runtime.CompilerServices.CompExactlyDependsOnAttribute/*02000255*/::.ctor(class System.Type/*02000038*/) /* 06001894 */ = ( 01 00 2B 53 79 73 74 65 6D 2E 52 75 6E 74 69 6D   // ..+System.Runtim
                                                                                                                                                                                   65 2E 49 6E 74 72 69 6E 73 69 63 73 2E 41 72 6D   // e.Intrinsics.Arm
                                                                                                                                                                                   2E 41 64 76 53 69 6D 64 2B 41 72 6D 36 34 00 00 ) // .AdvSimd+Arm64..

.method /*06000F96*/ private hidebysig static 
          void  EncodeToUtf16_Vector128(valuetype System.ReadOnlySpan`1/*020000D7*/<uint8> A_0,
                                        valuetype System.Span`1/*020000DB*/<char> A_1,
                                        valuetype System.HexConverter/*0200010C*//Casing/*0200010D*/ A_2) cil managed
  // SIG: 00 03 01 15 11 83 5C 01 05 15 11 83 6C 01 03 11 84 34
  {
    .custom /*0C000228:06001894*/ instance void System.Runtime.CompilerServices.CompExactlyDependsOnAttribute/*02000255*/::.ctor(class System.Type/*02000038*/) /* 06001894 */ = ( 01 00 23 53 79 73 74 65 6D 2E 52 75 6E 74 69 6D   // ..#System.Runtim
                                                                                                                                                                                   65 2E 49 6E 74 72 69 6E 73 69 63 73 2E 58 38 36   // e.Intrinsics.X86
                                                                                                                                                                                   2E 53 73 73 65 33 00 00 )                         // .Ssse3..