Ensure that Shuffle is marked as HW_Flag_CanBenefitFromConstantProp

[tannergooding]

Without this flag constants aren't propagated into Shuffle if there are two or more uses, which results in significantly worse codegen.

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[EgorBo]

LGTM assuming there are no other intrinsics needing this flag too

[tannergooding]

The example diff is as follows, which takes us from 380 to 59 bytes of codegen:

publicstaticVector4Cross(Vector4vector1,Vector4vector2){Vector128<float>v1=vector1.AsVector128();Vector128<float>v2=vector2.AsVector128();Vector128<int>shuftleYZXW=Vector128.Create(1,2,0,3);Vector128<int>shuftleZXYW=Vector128.Create(2,0,1,3);Vector128<float>m1=Vector128.Shuffle(v1,shuftleYZXW)*Vector128.Shuffle(v2,shuftleZXYW);Vector128<float>m2=Vector128.Shuffle(v1,shuftleZXYW)*Vector128.Shuffle(v2,shuftleYZXW);m2=m2.WithElement(3,0);return(m1-m2).AsVector4();}

Before

; Method Program:Cross(System.Numerics.Vector4,System.Numerics.Vector4):System.Numerics.Vector4 (FullOpts)G_M000_IG01: ;; offset=0x0000pushrbxsubrsp,320 vmovaps xmmword ptr [rsp+0x130],xmm6 vmovaps xmmword ptr [rsp+0x120],xmm7 vmovaps xmmword ptr [rsp+0x110],xmm8 vmovaps xmmword ptr [rsp+0x100],xmm9movrbx,rcxG_M000_IG02: ;; offset=0x002Fvmovupsxmm6, xmmword ptr [r8]vmovupsxmm7, xmmword ptr [reloc @RWD00]vmovupsxmm8, xmmword ptr [reloc @RWD16]vmovupsxmm9, xmmword ptr [rdx] vmovaps xmmword ptr [rsp+0xC0],xmm9 vmovaps xmmword ptr [rsp+0xB0],xmm7leardx,[rsp+0xC0]lear8,[rsp+0xB0]learcx,[rsp+0xD0]call[System.Runtime.Intrinsics.Vector128:Shuffle(System.Runtime.Intrinsics.Vector128`1[float],System.Runtime.Intrinsics.Vector128`1[int]):System.Runtime.Intrinsics.Vector128`1[float]] vmovaps xmm0, xmmword ptr [rsp+0xD0]vmovups xmmword ptr [rsp+0xF0],xmm0 vmovaps xmmword ptr [rsp+0x90],xmm6 vmovaps xmmword ptr [rsp+0x80],xmm8leardx,[rsp+0x90]lear8,[rsp+0x80]learcx,[rsp+0xA0]call[System.Runtime.Intrinsics.Vector128:Shuffle(System.Runtime.Intrinsics.Vector128`1[float],System.Runtime.Intrinsics.Vector128`1[int]):System.Runtime.Intrinsics.Vector128`1[float]]vmovupsxmm0, xmmword ptr [rsp+0xF0] vmulps xmm0,xmm0, xmmword ptr [rsp+0xA0]vmovups xmmword ptr [rsp+0xF0],xmm0 vmovaps xmmword ptr [rsp+0x60],xmm9 vmovaps xmmword ptr [rsp+0x50],xmm8leardx,[rsp+0x60]lear8,[rsp+0x50]learcx,[rsp+0x70]call[System.Runtime.Intrinsics.Vector128:Shuffle(System.Runtime.Intrinsics.Vector128`1[float],System.Runtime.Intrinsics.Vector128`1[int]):System.Runtime.Intrinsics.Vector128`1[float]] vmovaps xmm0, xmmword ptr [rsp+0x70]vmovups xmmword ptr [rsp+0xE0],xmm0 vmovaps xmmword ptr [rsp+0x30],xmm6 vmovaps xmmword ptr [rsp+0x20],xmm7leardx,[rsp+0x30]lear8,[rsp+0x20]learcx,[rsp+0x40]call[System.Runtime.Intrinsics.Vector128:Shuffle(System.Runtime.Intrinsics.Vector128`1[float],System.Runtime.Intrinsics.Vector128`1[int]):System.Runtime.Intrinsics.Vector128`1[float]]vmovupsxmm0, xmmword ptr [rsp+0xE0] vmulps xmm0,xmm0, xmmword ptr [rsp+0x40] vinsertps xmm0,xmm0,xmm0,56vmovupsxmm1, xmmword ptr [rsp+0xF0] vsubps xmm0,xmm1,xmm0vmovups xmmword ptr [rbx],xmm0movrax,rbxG_M000_IG03: ;; offset=0x014F vmovaps xmm6, xmmword ptr [rsp+0x130] vmovaps xmm7, xmmword ptr [rsp+0x120] vmovaps xmm8, xmmword ptr [rsp+0x110] vmovaps xmm9, xmmword ptr [rsp+0x100]addrsp,320poprbxretRWD00 dq	0000000200000001h,0000000300000000hRWD16 dq	0000000000000002h,0000000300000001h; Total bytes of code: 380

After

; Method Program:Cross(System.Numerics.Vector4,System.Numerics.Vector4):System.Numerics.Vector4 (FullOpts)G_M35725_IG01: ;; offset=0x0000 ;; size=0 bbWeight=1 PerfScore 0.00G_M35725_IG02: ;; offset=0x0000vmovupsxmm0, xmmword ptr [r8]vmovupsxmm1, xmmword ptr [rdx]vpermilpsxmm2,xmm1,-55vpermilpsxmm3,xmm0,-46 vmulps xmm2,xmm3,xmm2vpermilpsxmm1,xmm1,-46vpermilpsxmm0,xmm0,-55 vmulps xmm0,xmm0,xmm1 vinsertps xmm0,xmm0,xmm0,56 vsubps xmm0,xmm2,xmm0vmovups xmmword ptr [rcx],xmm0movrax,rcx ;; size=58 bbWeight=1 PerfScore 24.25G_M35725_IG03: ;; offset=0x003Aret ;; size=1 bbWeight=1 PerfScore 1.00; Total bytes of code: 59