JIT: Intrinsify Task/ValueTask factory methods

[jakobbotsch]

Intrinsify and recognize the following methods when used directly in runtime async context:

• Task.FromResult
• Task.CompletedTask
• ValueTask.FromResult
• ValueTask.CompletedTask
• new ValueTask()
• ValueTask-typed default
• new ValueTask<T>(T value)

Example

Before:

publicstaticasyncTaskMain(){awaitTaskCallee1();awaitTaskCallee2();awaitValueTaskCallee1();awaitValueTaskCallee2();awaitValueTaskCallee3();awaitValueTaskCallee4();awaitValueTaskCallee5();awaitValueTaskCallee6();}[MethodImpl(MethodImplOptions.NoInlining)]privatestaticTask<string>TaskCallee1(){returnTask.FromResult("abc");}[MethodImpl(MethodImplOptions.NoInlining)]privatestaticTaskTaskCallee2(){returnTask.CompletedTask;}[MethodImpl(MethodImplOptions.NoInlining)]privatestaticValueTaskValueTaskCallee1(){returnValueTask.CompletedTask;}[MethodImpl(MethodImplOptions.NoInlining)]privatestaticValueTaskValueTaskCallee2(){returndefault;}[MethodImpl(MethodImplOptions.NoInlining)]privatestaticValueTaskValueTaskCallee3(){returnnewValueTask();}[MethodImpl(MethodImplOptions.NoInlining)]privatestaticValueTask<string>ValueTaskCallee4(){returnValueTask.FromResult("abc");}[MethodImpl(MethodImplOptions.NoInlining)]privatestaticValueTask<string>ValueTaskCallee5(){returnnewValueTask<string>("abc");}[MethodImpl(MethodImplOptions.NoInlining)]privatestaticValueTask<Guid>ValueTaskCallee6(){returnnewValueTask<Guid>(Guid.NewGuid());}

; Assembly listing for method Program:TaskCallee1():System.String (FullOpts)G_M49327_IG01: ;; offset=0x0000pushrbxsubrsp,32 ;; size=5 bbWeight=1 PerfScore 1.25G_M49327_IG02: ;; offset=0x0005testrcx,rcxjne G_M49327_IG11movrcx,0x7FF9D8B84FF0 ; System.Threading.Tasks.Task`1[System.String]call CORINFO_HELP_NEWSFASTmovrbx,raxtest byte ptr [(reloc 0x7ff9d8b220e8)],1 ; global ptrje SHORT G_M49327_IG08 ;; size=36 bbWeight=1 PerfScore 5.75G_M49327_IG03: ;; offset=0x0029mov dword ptr [rbx+0x34],0x1000000movrcx,0x2A1BCEF3500 ; 'abc'mov gword ptr [rbx+0x38],rcxmovrcx,0x7FF9D8B66530 ; System.Threading.Tasks.Task:FromResult[System.String](System.String):System.Stringmovrcx, qword ptr [rcx+0x48]movrcx, qword ptr [rcx+0x10]testrcx,rcxje SHORT G_M49327_IG07 ;; size=44 bbWeight=1 PerfScore 7.75G_M49327_IG04: ;; offset=0x0055movr8,rbxxorrdx,rdxcall[System.Runtime.CompilerServices.AsyncHelpers:TransparentAwaitWithResult[System.__Canon](System.Threading.Tasks.Task`1[System.__Canon]):System.__Canon]testrcx,rcxjne SHORT G_M49327_IG09 ;; size=16 bbWeight=1 PerfScore 4.75G_M49327_IG05: ;; offset=0x0065xorecx,ecx ;; size=2 bbWeight=1 PerfScore 0.25G_M49327_IG06: ;; offset=0x0067addrsp,32poprbxret ;; size=6 bbWeight=1 PerfScore 1.75G_M49327_IG07: ;; offset=0x006Dmovrcx,0x7FF9D8B66530 ; System.Threading.Tasks.Task:FromResult[System.String](System.String):System.Stringmovrdx,0x7FF9D8B978D8 ; global ptrcall[CORINFO_HELP_RUNTIMEHANDLE_METHOD]movrcx,raxjmp SHORT G_M49327_IG04 ;; size=31 bbWeight=0.20 PerfScore 1.15G_M49327_IG08: ;; offset=0x008Cmovrcx,0x7FF9D8B21DA0 ; System.Threading.Tasks.Taskcall[CORINFO_HELP_GET_NONGCSTATIC_BASE]jmp SHORT G_M49327_IG03 ;; size=18 bbWeight=0 PerfScore 0.00G_M49327_IG09: ;; offset=0x009Emovrdx,0x7FF9D8B88EC0 ; Continuation_16_0_2call[CORINFO_HELP_ALLOC_CONTINUATION]movrbx,raxlearax,[reloc @RWD00]mov qword ptr [rbx+0x10],raxmov qword ptr [rbx+0x18],0x808call[System.Runtime.CompilerServices.AsyncHelpers:CaptureExecutionContext():System.Threading.ExecutionContext]movrdx,raxlearcx, bword ptr [rbx+0x20]call CORINFO_HELP_ASSIGN_REFmovrcx,rbxxoreax,eax ;; size=61 bbWeight=0 PerfScore 0.00G_M49327_IG10: ;; offset=0x00DBaddrsp,32poprbxret ;; size=6 bbWeight=0 PerfScore 0.00G_M49327_IG11: ;; offset=0x00E1movrax, gword ptr [rcx+0x28]xorrdx,rdxmov gword ptr [rcx+0x28],rdxjmp G_M49327_IG05 ;; size=15 bbWeight=0 PerfScore 0.00RWD00 dq	(dynamicClass):IL_STUB_AsyncResume_TaskCallee1_Optimized(System.Object,byref):System.Objectdq	G_M49327_IG09; Total bytes of code 240, prolog size 5, PerfScore 22.65, instruction count 53, allocated bytes for code 240 (MethodHash=c5e23f50) for method Program:TaskCallee1():System.String (FullOpts); ============================================================; Assembly listing for method Program:TaskCallee2() (FullOpts)G_M59144_IG01: ;; offset=0x0000pushrbxsubrsp,32 ;; size=5 bbWeight=1 PerfScore 1.25G_M59144_IG02: ;; offset=0x0005testrcx,rcxjne SHORT G_M59144_IG03movrdx,0x291A6000258 ; const ptrmovrdx, gword ptr [rdx]xorrcx,rcxcall[System.Runtime.CompilerServices.AsyncHelpers:TransparentAwaitWithResult(System.Threading.Tasks.Task)]testrcx,rcxjne SHORT G_M59144_IG05 ;; size=31 bbWeight=1 PerfScore 8.00G_M59144_IG03: ;; offset=0x0024xorecx,ecx ;; size=2 bbWeight=1 PerfScore 0.25G_M59144_IG04: ;; offset=0x0026addrsp,32poprbxret ;; size=6 bbWeight=1 PerfScore 1.75G_M59144_IG05: ;; offset=0x002Cmovrdx,0x7FF9D8BB2CD0 ; Continuation_8_0_1call[CORINFO_HELP_ALLOC_CONTINUATION]movrbx,raxlearax,[reloc @RWD00]mov qword ptr [rbx+0x10],raxmov qword ptr [rbx+0x18],8call[System.Runtime.CompilerServices.AsyncHelpers:CaptureExecutionContext():System.Threading.ExecutionContext]movrdx,raxlearcx, bword ptr [rbx+0x20]call CORINFO_HELP_ASSIGN_REFmovrcx,rbx ;; size=59 bbWeight=0 PerfScore 0.00G_M59144_IG06: ;; offset=0x0067addrsp,32poprbxret ;; size=6 bbWeight=0 PerfScore 0.00RWD00 dq	(dynamicClass):IL_STUB_AsyncResume_TaskCallee2_Optimized(System.Object,byref):System.Objectdq	G_M59144_IG05; Total bytes of code 109, prolog size 5, PerfScore 11.25, instruction count 28, allocated bytes for code 109 (MethodHash=f60418f7) for method Program:TaskCallee2() (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee1() (FullOpts)G_M60608_IG01: ;; offset=0x0000pushrbxsubrsp,48xoreax,eaxmov qword ptr [rsp+0x20],rax ;; size=12 bbWeight=1 PerfScore 2.50G_M60608_IG02: ;; offset=0x000Ctestrcx,rcxjne SHORT G_M60608_IG03xorrdx,rdxmov gword ptr [rsp+0x20],rdxmov word ptr [rsp+0x28],0mov byte ptr [rsp+0x2A],0leardx,[rsp+0x20]xorrcx,rcxcall[System.Runtime.CompilerServices.AsyncHelpers:TransparentAwaitWithResult(System.Threading.Tasks.ValueTask)]testrcx,rcxjne SHORT G_M60608_IG05 ;; size=42 bbWeight=1 PerfScore 9.50G_M60608_IG03: ;; offset=0x0036xorecx,ecx ;; size=2 bbWeight=1 PerfScore 0.25G_M60608_IG04: ;; offset=0x0038addrsp,48poprbxret ;; size=6 bbWeight=1 PerfScore 1.75G_M60608_IG05: ;; offset=0x003Emovrdx,0x7FF9D8BB2CD0 ; Continuation_8_0_1call[CORINFO_HELP_ALLOC_CONTINUATION]movrbx,raxlearax,[reloc @RWD00]mov qword ptr [rbx+0x10],raxmov qword ptr [rbx+0x18],8call[System.Runtime.CompilerServices.AsyncHelpers:CaptureExecutionContext():System.Threading.ExecutionContext]movrdx,raxlearcx, bword ptr [rbx+0x20]call CORINFO_HELP_ASSIGN_REFmovrcx,rbx ;; size=59 bbWeight=0 PerfScore 0.00G_M60608_IG06: ;; offset=0x0079addrsp,48poprbxret ;; size=6 bbWeight=0 PerfScore 0.00RWD00 dq	(dynamicClass):IL_STUB_AsyncResume_ValueTaskCallee1_Optimized(System.Object,byref):System.Objectdq	G_M60608_IG05; Total bytes of code 127, prolog size 12, PerfScore 14.00, instruction count 33, allocated bytes for code 127 (MethodHash=fdfd133f) for method Program:ValueTaskCallee1() (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee2() (FullOpts)G_M59587_IG01: ;; offset=0x0000subrsp,56xoreax,eaxmov qword ptr [rsp+0x28],raxmov qword ptr [rsp+0x30],rax ;; size=16 bbWeight=1 PerfScore 2.50G_M59587_IG02: ;; offset=0x0010xorrdx,rdxmov gword ptr [rsp+0x28],rdxmov word ptr [rsp+0x30],0mov byte ptr [rsp+0x32],0leardx,[rsp+0x28]xorrcx,rcxcall[System.Runtime.CompilerServices.AsyncHelpers:TransparentAwaitWithResult(System.Threading.Tasks.ValueTask)]testrcx,rcxjne SHORT G_M59587_IG04xorecx,ecx ;; size=39 bbWeight=1 PerfScore 8.50G_M59587_IG03: ;; offset=0x0037addrsp,56ret ;; size=5 bbWeight=1 PerfScore 1.25G_M59587_IG04: ;; offset=0x003Caddrsp,56ret ;; size=5 bbWeight=0 PerfScore 0.00; Total bytes of code 65, prolog size 16, PerfScore 12.25, instruction count 18, allocated bytes for code 65 (MethodHash=fdfd173c) for method Program:ValueTaskCallee2() (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee3() (FullOpts)G_M62786_IG01: ;; offset=0x0000subrsp,56xoreax,eaxmov qword ptr [rsp+0x28],raxmov qword ptr [rsp+0x30],rax ;; size=16 bbWeight=1 PerfScore 2.50G_M62786_IG02: ;; offset=0x0010xorrdx,rdxmov gword ptr [rsp+0x28],rdxmov word ptr [rsp+0x30],0mov byte ptr [rsp+0x32],0leardx,[rsp+0x28]xorrcx,rcxcall[System.Runtime.CompilerServices.AsyncHelpers:TransparentAwaitWithResult(System.Threading.Tasks.ValueTask)]testrcx,rcxjne SHORT G_M62786_IG04xorecx,ecx ;; size=39 bbWeight=1 PerfScore 8.50G_M62786_IG03: ;; offset=0x0037addrsp,56ret ;; size=5 bbWeight=1 PerfScore 1.25G_M62786_IG04: ;; offset=0x003Caddrsp,56ret ;; size=5 bbWeight=0 PerfScore 0.00; Total bytes of code 65, prolog size 16, PerfScore 12.25, instruction count 18, allocated bytes for code 65 (MethodHash=fdfd0abd) for method Program:ValueTaskCallee3() (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee4():System.String (FullOpts)G_M17761_IG01: ;; offset=0x0000pushrbxsubrsp,64 vxorps xmm4,xmm4,xmm4 vmovdqu xmmword ptr [rsp+0x28],xmm4xoreax,eaxmov qword ptr [rsp+0x38],rax ;; size=22 bbWeight=1 PerfScore 3.83G_M17761_IG02: ;; offset=0x0016testrcx,rcxjne G_M17761_IG09movrcx,0x7FF9D8BB50C8 ; System.Threading.Tasks.ValueTask:FromResult[System.String](System.String):System.Stringmovrcx, qword ptr [rcx+0x48]movrcx, qword ptr [rcx+0x10]testrcx,rcxje SHORT G_M17761_IG06 ;; size=32 bbWeight=1 PerfScore 6.75G_M17761_IG03: ;; offset=0x0036xorr8,r8mov gword ptr [rsp+0x28],r8movr8,0x2A1BCEF3500 ; 'abc'mov gword ptr [rsp+0x30],r8mov word ptr [rsp+0x38],0mov byte ptr [rsp+0x3A],1lear8,[rsp+0x28]xorrdx,rdxcall[System.Runtime.CompilerServices.AsyncHelpers:TransparentAwaitWithResult[System.__Canon](System.Threading.Tasks.ValueTask`1[System.__Canon]):System.__Canon]testrcx,rcxjne SHORT G_M17761_IG07 ;; size=53 bbWeight=1 PerfScore 9.50G_M17761_IG04: ;; offset=0x006Bxorecx,ecx ;; size=2 bbWeight=1 PerfScore 0.25G_M17761_IG05: ;; offset=0x006Daddrsp,64poprbxret ;; size=6 bbWeight=1 PerfScore 1.75G_M17761_IG06: ;; offset=0x0073movrcx,0x7FF9D8BB50C8 ; System.Threading.Tasks.ValueTask:FromResult[System.String](System.String):System.Stringmovrdx,0x7FF9D8BC17D0 ; global ptrcall CORINFO_HELP_RUNTIMEHANDLE_METHODmovrcx,raxjmp SHORT G_M17761_IG03 ;; size=30 bbWeight=0.20 PerfScore 0.75G_M17761_IG07: ;; offset=0x0091movrdx,0x7FF9D8B88EC0 ; Continuation_16_0_2call[CORINFO_HELP_ALLOC_CONTINUATION]movrbx,raxlearax,[reloc @RWD00]mov qword ptr [rbx+0x10],raxmov qword ptr [rbx+0x18],0x808call[System.Runtime.CompilerServices.AsyncHelpers:CaptureExecutionContext():System.Threading.ExecutionContext]movrdx,raxlearcx, bword ptr [rbx+0x20]call CORINFO_HELP_ASSIGN_REFmovrcx,rbxxoreax,eax ;; size=61 bbWeight=0 PerfScore 0.00G_M17761_IG08: ;; offset=0x00CEaddrsp,64poprbxret ;; size=6 bbWeight=0 PerfScore 0.00G_M17761_IG09: ;; offset=0x00D4movrax, gword ptr [rcx+0x28]xorrdx,rdxmov gword ptr [rcx+0x28],rdxjmp SHORT G_M17761_IG04 ;; size=12 bbWeight=0 PerfScore 0.00RWD00 dq	(dynamicClass):IL_STUB_AsyncResume_ValueTaskCallee4_Optimized(System.Object,byref):System.Objectdq	G_M17761_IG07; Total bytes of code 224, prolog size 22, PerfScore 22.83, instruction count 52, allocated bytes for code 224 (MethodHash=85dfba9e) for method Program:ValueTaskCallee4():System.String (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee5():System.String (FullOpts)G_M17504_IG01: ;; offset=0x0000subrsp,56 vxorps xmm4,xmm4,xmm4 vmovdqa xmmword ptr [rsp+0x20],xmm4xoreax,eaxmov qword ptr [rsp+0x30],rax ;; size=21 bbWeight=1 PerfScore 2.83G_M17504_IG02: ;; offset=0x0015xorr8,r8mov gword ptr [rsp+0x20],r8movr8,0x2A1BCEF3500 ; 'abc'mov gword ptr [rsp+0x28],r8mov word ptr [rsp+0x30],0mov byte ptr [rsp+0x32],1lear8,[rsp+0x20]movrcx,0x7FF9D8BB8000 ; System.Runtime.CompilerServices.AsyncHelpers:TransparentAwaitWithResult[System.String](System.Threading.Tasks.ValueTask`1[System.String]):System.Stringxorrdx,rdxcall[System.Runtime.CompilerServices.AsyncHelpers:TransparentAwaitWithResult[System.__Canon](System.Threading.Tasks.ValueTask`1[System.__Canon]):System.__Canon]testrcx,rcxjne SHORT G_M17504_IG04xorecx,ecx ;; size=65 bbWeight=1 PerfScore 10.00G_M17504_IG03: ;; offset=0x0056addrsp,56ret ;; size=5 bbWeight=1 PerfScore 1.25G_M17504_IG04: ;; offset=0x005Bxoreax,eax ;; size=2 bbWeight=0 PerfScore 0.00G_M17504_IG05: ;; offset=0x005Daddrsp,56ret ;; size=5 bbWeight=0 PerfScore 0.00; Total bytes of code 98, prolog size 21, PerfScore 14.08, instruction count 23, allocated bytes for code 98 (MethodHash=0100bb9f) for method Program:ValueTaskCallee5():System.String (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee6():System.Guid (FullOpts)G_M18761_IG01: ;; offset=0x0000pushrbppushr15pushr14pushr13pushr12pushrdipushrsipushrbxsubrsp,152vzeroupperlearbp,[rsp+0xD0]xoreax,eaxmov qword ptr [rbp-0x58],rax vxorps xmm4,xmm4,xmm4 vmovdqa xmmword ptr [rbp-0x50],xmm4mov qword ptr [rbp-0x40],raxmovrbx,rcx ;; size=52 bbWeight=1 PerfScore 13.58G_M18761_IG02: ;; offset=0x0034learcx,[rbp-0xB0]call CORINFO_HELP_INIT_PINVOKE_FRAMEmovrsi,raxmovrcx,rspmov qword ptr [rbp-0x98],rcxmovrcx,rbpmov qword ptr [rbp-0x88],rcxlearcx,[rbp-0x78]movrax,0x7FF9D8BBD8D8 ; function addressmov qword ptr [rbp-0xA0],raxlearax, G_M18761_IG04mov qword ptr [rbp-0x90],raxlearax,[rbp-0xB0]mov qword ptr [rsi+0x08],raxmov byte ptr [rsi+0x04],0 ;; size=85 bbWeight=1 PerfScore 10.50G_M18761_IG03: ;; offset=0x0089call[Interop+Ole32:CoCreateGuid(ptr):int] ;; size=6 bbWeight=1 PerfScore 3.00G_M18761_IG04: ;; offset=0x008Fmov byte ptr [rsi+0x04],1cmp dword ptr [(reloc 0x7ffa384dce38)],0je SHORT G_M18761_IG05call[CORINFO_HELP_STOP_FOR_GC] ;; size=19 bbWeight=1 PerfScore 7.00G_M18761_IG05: ;; offset=0x00A2movrcx, qword ptr [rbp-0xA8]mov qword ptr [rsi+0x08],rcxtesteax,eaxjne SHORT G_M18761_IG07vmovupsxmm0, xmmword ptr [rbp-0x78]vmovups xmmword ptr [rbp-0x4C],xmm0xorrcx,rcxmov gword ptr [rbp-0x58],rcxmov byte ptr [rbp-0x4E],1mov word ptr [rbp-0x50],0learcx,[rbp-0x68]lear8,[rbp-0x58]xorrdx,rdxcall[System.Runtime.CompilerServices.AsyncHelpers:TransparentAwaitWithResult[System.Guid](System.Threading.Tasks.ValueTask`1[System.Guid]):System.Guid]testrcx,rcxjne SHORT G_M18761_IG08vmovupsxmm0, xmmword ptr [rbp-0x68]vmovups xmmword ptr [rbx],xmm0movrax,rbxxorecx,ecx ;; size=76 bbWeight=1 PerfScore 16.50G_M18761_IG06: ;; offset=0x00EEaddrsp,152poprbxpoprsipoprdipopr12popr13popr14popr15poprbpret ;; size=20 bbWeight=1 PerfScore 5.25G_M18761_IG07: ;; offset=0x0102movecx,eaxcall[System.Guid:ThrowForHr(int)]int3 ;; size=9 bbWeight=0 PerfScore 0.00G_M18761_IG08: ;; offset=0x010Baddrsp,152poprbxpoprsipoprdipopr12popr13popr14popr15poprbpret ;; size=20 bbWeight=0 PerfScore 0.00; Total bytes of code 287, prolog size 49, PerfScore 55.83, instruction count 80, allocated bytes for code 287 (MethodHash=8d4cb6b6) for method Program:ValueTaskCallee6():System.Guid (FullOpts); ============================================================

After:

; Assembly listing for method Program:TaskCallee1():System.String (FullOpts)G_M49327_IG01: ;; offset=0x0000 ;; size=0 bbWeight=1 PerfScore 0.00G_M49327_IG02: ;; offset=0x0000movrax,0x2E8B7A73500 ; 'abc'xorecx,ecx ;; size=12 bbWeight=1 PerfScore 0.50G_M49327_IG03: ;; offset=0x000Cret ;; size=1 bbWeight=1 PerfScore 1.00; Total bytes of code 13, prolog size 0, PerfScore 1.50, instruction count 3, allocated bytes for code 13 (MethodHash=c5e23f50) for method Program:TaskCallee1():System.String (FullOpts); ============================================================; Assembly listing for method Program:TaskCallee2() (FullOpts)G_M59144_IG01: ;; offset=0x0000 ;; size=0 bbWeight=1 PerfScore 0.00G_M59144_IG02: ;; offset=0x0000xorecx,ecx ;; size=2 bbWeight=1 PerfScore 0.25G_M59144_IG03: ;; offset=0x0002ret ;; size=1 bbWeight=1 PerfScore 1.00; Total bytes of code 3, prolog size 0, PerfScore 1.25, instruction count 2, allocated bytes for code 3 (MethodHash=f60418f7) for method Program:TaskCallee2() (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee1() (FullOpts)G_M60608_IG01: ;; offset=0x0000 ;; size=0 bbWeight=1 PerfScore 0.00G_M60608_IG02: ;; offset=0x0000xorecx,ecx ;; size=2 bbWeight=1 PerfScore 0.25G_M60608_IG03: ;; offset=0x0002ret ;; size=1 bbWeight=1 PerfScore 1.00; Total bytes of code 3, prolog size 0, PerfScore 1.25, instruction count 2, allocated bytes for code 3 (MethodHash=fdfd133f) for method Program:ValueTaskCallee1() (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee2() (FullOpts)G_M59587_IG01: ;; offset=0x0000 ;; size=0 bbWeight=1 PerfScore 0.00G_M59587_IG02: ;; offset=0x0000xorecx,ecx ;; size=2 bbWeight=1 PerfScore 0.25G_M59587_IG03: ;; offset=0x0002ret ;; size=1 bbWeight=1 PerfScore 1.00; Total bytes of code 3, prolog size 0, PerfScore 1.25, instruction count 2, allocated bytes for code 3 (MethodHash=fdfd173c) for method Program:ValueTaskCallee2() (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee3() (FullOpts)G_M62786_IG01: ;; offset=0x0000 ;; size=0 bbWeight=1 PerfScore 0.00G_M62786_IG02: ;; offset=0x0000xorecx,ecx ;; size=2 bbWeight=1 PerfScore 0.25G_M62786_IG03: ;; offset=0x0002ret ;; size=1 bbWeight=1 PerfScore 1.00; Total bytes of code 3, prolog size 0, PerfScore 1.25, instruction count 2, allocated bytes for code 3 (MethodHash=fdfd0abd) for method Program:ValueTaskCallee3() (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee4():System.String (FullOpts)G_M17761_IG01: ;; offset=0x0000 ;; size=0 bbWeight=1 PerfScore 0.00G_M17761_IG02: ;; offset=0x0000movrax,0x2E8B7A73500 ; 'abc'xorecx,ecx ;; size=12 bbWeight=1 PerfScore 0.50G_M17761_IG03: ;; offset=0x000Cret ;; size=1 bbWeight=1 PerfScore 1.00; Total bytes of code 13, prolog size 0, PerfScore 1.50, instruction count 3, allocated bytes for code 13 (MethodHash=85dfba9e) for method Program:ValueTaskCallee4():System.String (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee5():System.String (FullOpts)G_M17504_IG01: ;; offset=0x0000 ;; size=0 bbWeight=1 PerfScore 0.00G_M17504_IG02: ;; offset=0x0000movrax,0x2E8B7A73500 ; 'abc'xorecx,ecx ;; size=12 bbWeight=1 PerfScore 0.50G_M17504_IG03: ;; offset=0x000Cret ;; size=1 bbWeight=1 PerfScore 1.00; Total bytes of code 13, prolog size 0, PerfScore 1.50, instruction count 3, allocated bytes for code 13 (MethodHash=0100bb9f) for method Program:ValueTaskCallee5():System.String (FullOpts); ============================================================; Assembly listing for method Program:ValueTaskCallee6():System.Guid (FullOpts)G_M18761_IG01: ;; offset=0x0000pushrbppushr15pushr14pushr13pushr12pushrdipushrsipushrbxsubrsp,104vzeroupperlearbp,[rsp+0xA0]movrbx,rcx ;; size=30 bbWeight=1 PerfScore 10.00G_M18761_IG02: ;; offset=0x001Elearcx,[rbp-0x80]call CORINFO_HELP_INIT_PINVOKE_FRAMEmovrsi,raxmovrcx,rspmov qword ptr [rbp-0x68],rcxmovrcx,rbpmov qword ptr [rbp-0x58],rcxlearcx,[rbp-0x48]movrax,0x7FF9D8B7A8D8 ; function addressmov qword ptr [rbp-0x70],raxlearax, G_M18761_IG04mov qword ptr [rbp-0x60],raxlearax,[rbp-0x80]mov qword ptr [rsi+0x08],raxmov byte ptr [rsi+0x04],0 ;; size=67 bbWeight=1 PerfScore 10.50G_M18761_IG03: ;; offset=0x0061call[Interop+Ole32:CoCreateGuid(ptr):int] ;; size=6 bbWeight=1 PerfScore 3.00G_M18761_IG04: ;; offset=0x0067mov byte ptr [rsi+0x04],1cmp dword ptr [(reloc 0x7ffa384dcdb8)],0je SHORT G_M18761_IG05call[CORINFO_HELP_STOP_FOR_GC] ;; size=19 bbWeight=1 PerfScore 7.00G_M18761_IG05: ;; offset=0x007Amovrcx, qword ptr [rbp-0x78]mov qword ptr [rsi+0x08],rcxmovecx,eaxtestecx,ecxjne SHORT G_M18761_IG07vmovupsxmm0, xmmword ptr [rbp-0x48]vmovups xmmword ptr [rbx],xmm0movrax,rbxxorecx,ecx ;; size=28 bbWeight=1 PerfScore 6.00G_M18761_IG06: ;; offset=0x0096addrsp,104poprbxpoprsipoprdipopr12popr13popr14popr15poprbpret ;; size=17 bbWeight=1 PerfScore 5.25G_M18761_IG07: ;; offset=0x00A7call[System.Guid:ThrowForHr(int)]int3 ;; size=7 bbWeight=0 PerfScore 0.00; Total bytes of code 174, prolog size 27, PerfScore 41.75, instruction count 53, allocated bytes for code 174 (MethodHash=8d4cb6b6) for method Program:ValueTaskCallee6():System.Guid (FullOpts); ============================================================

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Pull request overview

This PR extends the CoreCLR JIT’s “runtime async” optimization pipeline by marking common Task/ValueTask factory helpers as intrinsics and teaching the importer to fold/avoid AsyncHelpers.TransparentAwaitWithResult in more cases, reducing call/alloc overhead in optimized async-return paths.

Changes:

• Mark Task.CompletedTask, Task.FromResult, ValueTask.CompletedTask, ValueTask.FromResult, and ValueTask<TResult>(TResult) with [Intrinsic] to enable JIT recognition.
• Add new JIT NamedIntrinsic IDs plus importer expansion logic for async-callconv FromResult / CompletedTask, and add a new impFoldAwaitedTopOfStack fast-path for certain ValueTask return patterns.
• Improve debug local naming by labeling ASYNC_CONTINUATION_ILNUM locals as AsyncCont.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/ValueTask.cs	Adds [Intrinsic] to ValueTask.CompletedTask, ValueTask.FromResult, and ValueTask<TResult>(TResult) ctor to enable JIT recognition.
src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs	Adds [Intrinsic] to Task.CompletedTask getter and Task.FromResult to enable async-callconv intrinsic expansion.
src/coreclr/jit/namedintrinsiclist.h	Introduces new NamedIntrinsic entries for Task/ValueTask factory methods used by the importer.
src/coreclr/jit/importercalls.cpp	Implements async-callconv intrinsic expansion/folding for FromResult/CompletedTask, and extends intrinsic lookup for Task/ValueTask methods.
src/coreclr/jit/importer.cpp	Refactors return/await wrapping logic and adds impFoldAwaitedTopOfStack to avoid unnecessary TransparentAwaitWithResult calls.
src/coreclr/jit/gentree.cpp	Improves local name printing by labeling async continuation locals as AsyncCont.
src/coreclr/jit/compiler.h	Adds the impFoldAwaitedTopOfStack declaration.

[jakobbotsch]

cc @dotnet/jit-contrib PTAL @EgorBo

[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated no new comments.