Enable FEATURE_MULTICASTSTUB_AS_IL for Windows x86 by huoyaoyuan · Pull Request #104192 · dotnet/runtime

huoyaoyuan · 2024-06-29T11:10:10Z

Local benchmark result for Action<int> on x86:

Method	Job	Toolchain	Mean	Error	StdDev	Ratio
SingleArg	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	3.464 ns	0.0127 ns	0.0119 ns	0.95
SingleArg	Job-KBQPJV	\x86-main\corerun.exe	3.661 ns	0.0222 ns	0.0208 ns	1.00

ManyCast	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	8.188 ns	0.0944 ns	0.0883 ns	0.97
ManyCast	Job-KBQPJV	\x86-main\corerun.exe	8.483 ns	0.0888 ns	0.0831 ns	1.00

ManyArg_RetFPU	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	5.566 ns	0.0338 ns	0.0316 ns	0.96
ManyArg_RetFPU	Job-KBQPJV	\x86-main\corerun.exe	5.771 ns	0.0212 ns	0.0177 ns	1.00

huoyaoyuan · 2024-06-29T11:11:56Z

@EgorBot -intel -amd -arm64

usingBenchmarkDotNet.Attributes;usingSystem;namespaceBenchmarkGround{publicstructGCStruct{publicobjecta,b,c,d,e,f,h,g;}publicclassBench{privatereadonlyobjectobj=newobject();privatereadonlyGuidguid=Guid.NewGuid();privatereadonlyGCStructgcStruct=newGCStruct{a=newobject(),g=newobject()};privatereadonlyAction<int>singleArg=(Action<int>)delegate{}+delegate{};privatereadonlyAction<int>manyCast=(Action<int>)delegate{}+delegate{}+delegate{}+delegate{}+delegate{}+delegate{};privatereadonlyFunc<int,double,Guid,GCStruct,object,double>manyArg_RetFPU=(Func<int,double,Guid,GCStruct,object,double>)delegate{return123.456;}+delegate{return654.321;};[Benchmark]publicvoidSingleArg()=>singleArg(42);[Benchmark]publicvoidManyCast()=>manyCast(42);[Benchmark]publicdoubleManyArg_RetFPU()=>manyArg_RetFPU(42,123.0,guid,gcStruct,obj);}}

dotnet-policy-service · 2024-06-29T11:14:38Z

Tagging subscribers to this area: @mangod9
See info in area-owners.md if you want to be subscribed.

EgorBot · 2024-06-29T11:54:29Z

Benchmark results on Intel

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 8 logical and 4 physical cores
Job-FAGYWG : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
Job-LQQTSO : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	8.084 ns	0.0012 ns	1.00
SingleArg	PR	6.078 ns	0.0012 ns	0.75

ManyCast	Main	19.581 ns	0.0313 ns	1.00
ManyCast	PR	14.887 ns	0.1134 ns	0.76

ManyArg_RetFPU	Main	14.538 ns	0.0340 ns	1.00
ManyArg_RetFPU	PR	11.450 ns	0.0147 ns	0.79

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:24Z

Benchmark results on Arm64

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Unknown processor
Job-LOUVQC : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD
Job-TLYWZG : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	15.831 ns	0.0109 ns	1.00
SingleArg	PR	8.772 ns	0.0017 ns	0.55

ManyCast	Main	38.106 ns	0.0234 ns	1.00
ManyCast	PR	21.135 ns	0.0015 ns	0.55

ManyArg_RetFPU	Main	17.636 ns	0.0024 ns	1.00
ManyArg_RetFPU	PR	16.759 ns	0.0071 ns	0.95

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:44Z

Benchmark results on Amd

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
AMD EPYC 7763, 1 CPU, 8 logical and 4 physical cores
Job-DXSXUL : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2
Job-BIEGFU : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	13.008 ns	0.1016 ns	1.00
SingleArg	PR	6.490 ns	0.0071 ns	0.50

ManyCast	Main	100.460 ns	0.5200 ns	1.00
ManyCast	PR	18.849 ns	0.0302 ns	0.19

ManyArg_RetFPU	Main	14.358 ns	0.0464 ns	1.00
ManyArg_RetFPU	PR	12.682 ns	0.0120 ns	0.88

BDN_Artifacts.zip

jkotas · 2024-06-29T12:15:38Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


Suggested change
pCode->EmitBRTRUE(invokeTraceHelper);
pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
pCode->EmitLabel(invokeTraceHelper);
pCode->EmitLoadThis();
pCode->EmitLDLOC(dwLoopCounterNum);
pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);
pCode->EmitBRTRUE(invokeTraceHelper);
And move the debugging path to be after RET:
pCode->EmitRET(); #ifdef DEBUGGING_SUPPORTED // Emit debugging support at the end of the method for better perf pCode->EmitLabel(invokeTraceHelper); pCode->EmitLoadThis(); pCode->EmitLDLOC(dwLoopCounterNum); pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0); pCode->EmitBR(debuggerCheckEnd); #endif
This should be even better

That was exactly what I did locally, and resulted in exact same codegen with current, at least for x86. The compiled asm code block order did follow IL block order exactly.
@dotnet/jit-contrib Do you have any suggestion on this?

This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

Well normalizing the loop closer to a for loop results in about 5% improvement for ManyArg case, but 5% regression for ManyCast.

Codegen for x64 now:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esicmp qword ptr [rbx+0x30],0jle SHORT G_M000_IG05G_M000_IG03: ;; offset=0x0012test dword ptr [(reloc 0x7ff824c55210)],512jne SHORT G_M000_IG06G_M000_IG04: ;; offset=0x001Emovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG07movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesimovsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03G_M000_IG05: ;; offset=0x003Eaddrsp,40poprbxpoprsiretG_M000_IG06: ;; offset=0x0045movrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG04G_M000_IG07: ;; offset=0x0051call CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 87

jkotas

LGTM otherwise. Nice simplification!

jkotas · 2024-06-29T20:08:17Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

jkotas · 2024-06-30T14:59:13Z

 pCode->EmitLDC(0);
 pCode->EmitSTLOC(dwLoopCounterNum);

+ // Make the shape of the loop similar to what C# compiler emits


The new shape seems to be missing the invocation of the trace helper at the end. E.g. if the invocation count is 2, the trace helper should be called 3 times. It is only called 2 times if I am reading the code correctly.

Fixed. Result codegen:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esijmp SHORT G_M000_IG04G_M000_IG03: ;; offset=0x000Dmovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG08movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesiG_M000_IG04: ;; offset=0x0024test dword ptr [(reloc 0x7ff84ea05210)],512jne SHORT G_M000_IG06G_M000_IG05: ;; offset=0x0030movsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03jmp SHORT G_M000_IG07G_M000_IG06: ;; offset=0x003Bmovrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG05G_M000_IG07: ;; offset=0x0047addrsp,40poprbxpoprsiretG_M000_IG08: ;; offset=0x004Ecall CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 84
JIT reorders the debugging block in front of the ret. Benchmark shows no regression. It's just a bit strange with the unconditional jumps.

huoyaoyuan · 2024-06-29T11:10:10Z

Closes#103958 .

Local benchmark result for Action<int> on x86:

Method	Job	Toolchain	Mean	Error	StdDev	Ratio
SingleArg	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	3.464 ns	0.0127 ns	0.0119 ns	0.95
SingleArg	Job-KBQPJV	\x86-main\corerun.exe	3.661 ns	0.0222 ns	0.0208 ns	1.00

ManyCast	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	8.188 ns	0.0944 ns	0.0883 ns	0.97
ManyCast	Job-KBQPJV	\x86-main\corerun.exe	8.483 ns	0.0888 ns	0.0831 ns	1.00

ManyArg_RetFPU	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	5.566 ns	0.0338 ns	0.0316 ns	0.96
ManyArg_RetFPU	Job-KBQPJV	\x86-main\corerun.exe	5.771 ns	0.0212 ns	0.0177 ns	1.00

huoyaoyuan · 2024-06-29T11:11:56Z

@EgorBot -intel -amd -arm64

usingBenchmarkDotNet.Attributes;usingSystem;namespaceBenchmarkGround{publicstructGCStruct{publicobjecta,b,c,d,e,f,h,g;}publicclassBench{privatereadonlyobjectobj=newobject();privatereadonlyGuidguid=Guid.NewGuid();privatereadonlyGCStructgcStruct=newGCStruct{a=newobject(),g=newobject()};privatereadonlyAction<int>singleArg=(Action<int>)delegate{}+delegate{};privatereadonlyAction<int>manyCast=(Action<int>)delegate{}+delegate{}+delegate{}+delegate{}+delegate{}+delegate{};privatereadonlyFunc<int,double,Guid,GCStruct,object,double>manyArg_RetFPU=(Func<int,double,Guid,GCStruct,object,double>)delegate{return123.456;}+delegate{return654.321;};[Benchmark]publicvoidSingleArg()=>singleArg(42);[Benchmark]publicvoidManyCast()=>manyCast(42);[Benchmark]publicdoubleManyArg_RetFPU()=>manyArg_RetFPU(42,123.0,guid,gcStruct,obj);}}

dotnet-policy-service · 2024-06-29T11:14:38Z

Tagging subscribers to this area: @mangod9
See info in area-owners.md if you want to be subscribed.

EgorBot · 2024-06-29T11:54:29Z

Benchmark results on Intel

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 8 logical and 4 physical cores
Job-FAGYWG : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
Job-LQQTSO : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	8.084 ns	0.0012 ns	1.00
SingleArg	PR	6.078 ns	0.0012 ns	0.75

ManyCast	Main	19.581 ns	0.0313 ns	1.00
ManyCast	PR	14.887 ns	0.1134 ns	0.76

ManyArg_RetFPU	Main	14.538 ns	0.0340 ns	1.00
ManyArg_RetFPU	PR	11.450 ns	0.0147 ns	0.79

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:24Z

Benchmark results on Arm64

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Unknown processor
Job-LOUVQC : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD
Job-TLYWZG : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	15.831 ns	0.0109 ns	1.00
SingleArg	PR	8.772 ns	0.0017 ns	0.55

ManyCast	Main	38.106 ns	0.0234 ns	1.00
ManyCast	PR	21.135 ns	0.0015 ns	0.55

ManyArg_RetFPU	Main	17.636 ns	0.0024 ns	1.00
ManyArg_RetFPU	PR	16.759 ns	0.0071 ns	0.95

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:44Z

Benchmark results on Amd

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
AMD EPYC 7763, 1 CPU, 8 logical and 4 physical cores
Job-DXSXUL : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2
Job-BIEGFU : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	13.008 ns	0.1016 ns	1.00
SingleArg	PR	6.490 ns	0.0071 ns	0.50

ManyCast	Main	100.460 ns	0.5200 ns	1.00
ManyCast	PR	18.849 ns	0.0302 ns	0.19

ManyArg_RetFPU	Main	14.358 ns	0.0464 ns	1.00
ManyArg_RetFPU	PR	12.682 ns	0.0120 ns	0.88

BDN_Artifacts.zip

jkotas · 2024-06-29T12:15:38Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


Suggested change
pCode->EmitBRTRUE(invokeTraceHelper);
pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
pCode->EmitLabel(invokeTraceHelper);
pCode->EmitLoadThis();
pCode->EmitLDLOC(dwLoopCounterNum);
pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);
pCode->EmitBRTRUE(invokeTraceHelper);
And move the debugging path to be after RET:
pCode->EmitRET(); #ifdef DEBUGGING_SUPPORTED // Emit debugging support at the end of the method for better perf pCode->EmitLabel(invokeTraceHelper); pCode->EmitLoadThis(); pCode->EmitLDLOC(dwLoopCounterNum); pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0); pCode->EmitBR(debuggerCheckEnd); #endif
This should be even better

That was exactly what I did locally, and resulted in exact same codegen with current, at least for x86. The compiled asm code block order did follow IL block order exactly.
@dotnet/jit-contrib Do you have any suggestion on this?

This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

Well normalizing the loop closer to a for loop results in about 5% improvement for ManyArg case, but 5% regression for ManyCast.

Codegen for x64 now:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esicmp qword ptr [rbx+0x30],0jle SHORT G_M000_IG05G_M000_IG03: ;; offset=0x0012test dword ptr [(reloc 0x7ff824c55210)],512jne SHORT G_M000_IG06G_M000_IG04: ;; offset=0x001Emovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG07movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesimovsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03G_M000_IG05: ;; offset=0x003Eaddrsp,40poprbxpoprsiretG_M000_IG06: ;; offset=0x0045movrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG04G_M000_IG07: ;; offset=0x0051call CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 87

jkotas

LGTM otherwise. Nice simplification!

jkotas · 2024-06-29T20:08:17Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

jkotas · 2024-06-30T14:59:13Z

 pCode->EmitLDC(0);
 pCode->EmitSTLOC(dwLoopCounterNum);

+ // Make the shape of the loop similar to what C# compiler emits


The new shape seems to be missing the invocation of the trace helper at the end. E.g. if the invocation count is 2, the trace helper should be called 3 times. It is only called 2 times if I am reading the code correctly.

Fixed. Result codegen:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esijmp SHORT G_M000_IG04G_M000_IG03: ;; offset=0x000Dmovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG08movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesiG_M000_IG04: ;; offset=0x0024test dword ptr [(reloc 0x7ff84ea05210)],512jne SHORT G_M000_IG06G_M000_IG05: ;; offset=0x0030movsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03jmp SHORT G_M000_IG07G_M000_IG06: ;; offset=0x003Bmovrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG05G_M000_IG07: ;; offset=0x0047addrsp,40poprbxpoprsiretG_M000_IG08: ;; offset=0x004Ecall CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 84
JIT reorders the debugging block in front of the ret. Benchmark shows no regression. It's just a bit strange with the unconditional jumps.

huoyaoyuan · 2024-06-29T11:10:10Z

Closes#103958 .

Local benchmark result for Action<int> on x86:

Method	Job	Toolchain	Mean	Error	StdDev	Ratio
SingleArg	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	3.464 ns	0.0127 ns	0.0119 ns	0.95
SingleArg	Job-KBQPJV	\x86-main\corerun.exe	3.661 ns	0.0222 ns	0.0208 ns	1.00

ManyCast	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	8.188 ns	0.0944 ns	0.0883 ns	0.97
ManyCast	Job-KBQPJV	\x86-main\corerun.exe	8.483 ns	0.0888 ns	0.0831 ns	1.00

ManyArg_RetFPU	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	5.566 ns	0.0338 ns	0.0316 ns	0.96
ManyArg_RetFPU	Job-KBQPJV	\x86-main\corerun.exe	5.771 ns	0.0212 ns	0.0177 ns	1.00

huoyaoyuan · 2024-06-29T11:11:56Z

@EgorBot -intel -amd -arm64

usingBenchmarkDotNet.Attributes;usingSystem;namespaceBenchmarkGround{publicstructGCStruct{publicobjecta,b,c,d,e,f,h,g;}publicclassBench{privatereadonlyobjectobj=newobject();privatereadonlyGuidguid=Guid.NewGuid();privatereadonlyGCStructgcStruct=newGCStruct{a=newobject(),g=newobject()};privatereadonlyAction<int>singleArg=(Action<int>)delegate{}+delegate{};privatereadonlyAction<int>manyCast=(Action<int>)delegate{}+delegate{}+delegate{}+delegate{}+delegate{}+delegate{};privatereadonlyFunc<int,double,Guid,GCStruct,object,double>manyArg_RetFPU=(Func<int,double,Guid,GCStruct,object,double>)delegate{return123.456;}+delegate{return654.321;};[Benchmark]publicvoidSingleArg()=>singleArg(42);[Benchmark]publicvoidManyCast()=>manyCast(42);[Benchmark]publicdoubleManyArg_RetFPU()=>manyArg_RetFPU(42,123.0,guid,gcStruct,obj);}}

dotnet-policy-service · 2024-06-29T11:14:38Z

Tagging subscribers to this area: @mangod9
See info in area-owners.md if you want to be subscribed.

EgorBot · 2024-06-29T11:54:29Z

Benchmark results on Intel

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 8 logical and 4 physical cores
Job-FAGYWG : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
Job-LQQTSO : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	8.084 ns	0.0012 ns	1.00
SingleArg	PR	6.078 ns	0.0012 ns	0.75

ManyCast	Main	19.581 ns	0.0313 ns	1.00
ManyCast	PR	14.887 ns	0.1134 ns	0.76

ManyArg_RetFPU	Main	14.538 ns	0.0340 ns	1.00
ManyArg_RetFPU	PR	11.450 ns	0.0147 ns	0.79

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:24Z

Benchmark results on Arm64

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Unknown processor
Job-LOUVQC : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD
Job-TLYWZG : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	15.831 ns	0.0109 ns	1.00
SingleArg	PR	8.772 ns	0.0017 ns	0.55

ManyCast	Main	38.106 ns	0.0234 ns	1.00
ManyCast	PR	21.135 ns	0.0015 ns	0.55

ManyArg_RetFPU	Main	17.636 ns	0.0024 ns	1.00
ManyArg_RetFPU	PR	16.759 ns	0.0071 ns	0.95

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:44Z

Benchmark results on Amd

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
AMD EPYC 7763, 1 CPU, 8 logical and 4 physical cores
Job-DXSXUL : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2
Job-BIEGFU : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	13.008 ns	0.1016 ns	1.00
SingleArg	PR	6.490 ns	0.0071 ns	0.50

ManyCast	Main	100.460 ns	0.5200 ns	1.00
ManyCast	PR	18.849 ns	0.0302 ns	0.19

ManyArg_RetFPU	Main	14.358 ns	0.0464 ns	1.00
ManyArg_RetFPU	PR	12.682 ns	0.0120 ns	0.88

BDN_Artifacts.zip

jkotas · 2024-06-29T12:15:38Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


Suggested change
pCode->EmitBRTRUE(invokeTraceHelper);
pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
pCode->EmitLabel(invokeTraceHelper);
pCode->EmitLoadThis();
pCode->EmitLDLOC(dwLoopCounterNum);
pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);
pCode->EmitBRTRUE(invokeTraceHelper);
And move the debugging path to be after RET:
pCode->EmitRET(); #ifdef DEBUGGING_SUPPORTED // Emit debugging support at the end of the method for better perf pCode->EmitLabel(invokeTraceHelper); pCode->EmitLoadThis(); pCode->EmitLDLOC(dwLoopCounterNum); pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0); pCode->EmitBR(debuggerCheckEnd); #endif
This should be even better

That was exactly what I did locally, and resulted in exact same codegen with current, at least for x86. The compiled asm code block order did follow IL block order exactly.
@dotnet/jit-contrib Do you have any suggestion on this?

This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

Well normalizing the loop closer to a for loop results in about 5% improvement for ManyArg case, but 5% regression for ManyCast.

Codegen for x64 now:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esicmp qword ptr [rbx+0x30],0jle SHORT G_M000_IG05G_M000_IG03: ;; offset=0x0012test dword ptr [(reloc 0x7ff824c55210)],512jne SHORT G_M000_IG06G_M000_IG04: ;; offset=0x001Emovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG07movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesimovsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03G_M000_IG05: ;; offset=0x003Eaddrsp,40poprbxpoprsiretG_M000_IG06: ;; offset=0x0045movrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG04G_M000_IG07: ;; offset=0x0051call CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 87

jkotas

LGTM otherwise. Nice simplification!

jkotas · 2024-06-29T20:08:17Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

jkotas · 2024-06-30T14:59:13Z

 pCode->EmitLDC(0);
 pCode->EmitSTLOC(dwLoopCounterNum);

+ // Make the shape of the loop similar to what C# compiler emits


The new shape seems to be missing the invocation of the trace helper at the end. E.g. if the invocation count is 2, the trace helper should be called 3 times. It is only called 2 times if I am reading the code correctly.

Fixed. Result codegen:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esijmp SHORT G_M000_IG04G_M000_IG03: ;; offset=0x000Dmovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG08movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesiG_M000_IG04: ;; offset=0x0024test dword ptr [(reloc 0x7ff84ea05210)],512jne SHORT G_M000_IG06G_M000_IG05: ;; offset=0x0030movsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03jmp SHORT G_M000_IG07G_M000_IG06: ;; offset=0x003Bmovrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG05G_M000_IG07: ;; offset=0x0047addrsp,40poprbxpoprsiretG_M000_IG08: ;; offset=0x004Ecall CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 84
JIT reorders the debugging block in front of the ret. Benchmark shows no regression. It's just a bit strange with the unconditional jumps.

huoyaoyuan · 2024-06-29T11:10:10Z

Closes#103958 .

Local benchmark result for Action<int> on x86:

Method	Job	Toolchain	Mean	Error	StdDev	Ratio
SingleArg	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	3.464 ns	0.0127 ns	0.0119 ns	0.95
SingleArg	Job-KBQPJV	\x86-main\corerun.exe	3.661 ns	0.0222 ns	0.0208 ns	1.00

ManyCast	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	8.188 ns	0.0944 ns	0.0883 ns	0.97
ManyCast	Job-KBQPJV	\x86-main\corerun.exe	8.483 ns	0.0888 ns	0.0831 ns	1.00

ManyArg_RetFPU	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	5.566 ns	0.0338 ns	0.0316 ns	0.96
ManyArg_RetFPU	Job-KBQPJV	\x86-main\corerun.exe	5.771 ns	0.0212 ns	0.0177 ns	1.00

huoyaoyuan · 2024-06-29T11:11:56Z

@EgorBot -intel -amd -arm64

usingBenchmarkDotNet.Attributes;usingSystem;namespaceBenchmarkGround{publicstructGCStruct{publicobjecta,b,c,d,e,f,h,g;}publicclassBench{privatereadonlyobjectobj=newobject();privatereadonlyGuidguid=Guid.NewGuid();privatereadonlyGCStructgcStruct=newGCStruct{a=newobject(),g=newobject()};privatereadonlyAction<int>singleArg=(Action<int>)delegate{}+delegate{};privatereadonlyAction<int>manyCast=(Action<int>)delegate{}+delegate{}+delegate{}+delegate{}+delegate{}+delegate{};privatereadonlyFunc<int,double,Guid,GCStruct,object,double>manyArg_RetFPU=(Func<int,double,Guid,GCStruct,object,double>)delegate{return123.456;}+delegate{return654.321;};[Benchmark]publicvoidSingleArg()=>singleArg(42);[Benchmark]publicvoidManyCast()=>manyCast(42);[Benchmark]publicdoubleManyArg_RetFPU()=>manyArg_RetFPU(42,123.0,guid,gcStruct,obj);}}

dotnet-policy-service · 2024-06-29T11:14:38Z

Tagging subscribers to this area: @mangod9
See info in area-owners.md if you want to be subscribed.

EgorBot · 2024-06-29T11:54:29Z

Benchmark results on Intel

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 8 logical and 4 physical cores
Job-FAGYWG : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
Job-LQQTSO : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	8.084 ns	0.0012 ns	1.00
SingleArg	PR	6.078 ns	0.0012 ns	0.75

ManyCast	Main	19.581 ns	0.0313 ns	1.00
ManyCast	PR	14.887 ns	0.1134 ns	0.76

ManyArg_RetFPU	Main	14.538 ns	0.0340 ns	1.00
ManyArg_RetFPU	PR	11.450 ns	0.0147 ns	0.79

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:24Z

Benchmark results on Arm64

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Unknown processor
Job-LOUVQC : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD
Job-TLYWZG : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	15.831 ns	0.0109 ns	1.00
SingleArg	PR	8.772 ns	0.0017 ns	0.55

ManyCast	Main	38.106 ns	0.0234 ns	1.00
ManyCast	PR	21.135 ns	0.0015 ns	0.55

ManyArg_RetFPU	Main	17.636 ns	0.0024 ns	1.00
ManyArg_RetFPU	PR	16.759 ns	0.0071 ns	0.95

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:44Z

Benchmark results on Amd

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
AMD EPYC 7763, 1 CPU, 8 logical and 4 physical cores
Job-DXSXUL : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2
Job-BIEGFU : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	13.008 ns	0.1016 ns	1.00
SingleArg	PR	6.490 ns	0.0071 ns	0.50

ManyCast	Main	100.460 ns	0.5200 ns	1.00
ManyCast	PR	18.849 ns	0.0302 ns	0.19

ManyArg_RetFPU	Main	14.358 ns	0.0464 ns	1.00
ManyArg_RetFPU	PR	12.682 ns	0.0120 ns	0.88

BDN_Artifacts.zip

jkotas · 2024-06-29T12:15:38Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


Suggested change
pCode->EmitBRTRUE(invokeTraceHelper);
pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
pCode->EmitLabel(invokeTraceHelper);
pCode->EmitLoadThis();
pCode->EmitLDLOC(dwLoopCounterNum);
pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);
pCode->EmitBRTRUE(invokeTraceHelper);
And move the debugging path to be after RET:
pCode->EmitRET(); #ifdef DEBUGGING_SUPPORTED // Emit debugging support at the end of the method for better perf pCode->EmitLabel(invokeTraceHelper); pCode->EmitLoadThis(); pCode->EmitLDLOC(dwLoopCounterNum); pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0); pCode->EmitBR(debuggerCheckEnd); #endif
This should be even better

That was exactly what I did locally, and resulted in exact same codegen with current, at least for x86. The compiled asm code block order did follow IL block order exactly.
@dotnet/jit-contrib Do you have any suggestion on this?

This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

Well normalizing the loop closer to a for loop results in about 5% improvement for ManyArg case, but 5% regression for ManyCast.

Codegen for x64 now:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esicmp qword ptr [rbx+0x30],0jle SHORT G_M000_IG05G_M000_IG03: ;; offset=0x0012test dword ptr [(reloc 0x7ff824c55210)],512jne SHORT G_M000_IG06G_M000_IG04: ;; offset=0x001Emovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG07movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesimovsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03G_M000_IG05: ;; offset=0x003Eaddrsp,40poprbxpoprsiretG_M000_IG06: ;; offset=0x0045movrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG04G_M000_IG07: ;; offset=0x0051call CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 87

jkotas

LGTM otherwise. Nice simplification!

jkotas · 2024-06-29T20:08:17Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

jkotas · 2024-06-30T14:59:13Z

 pCode->EmitLDC(0);
 pCode->EmitSTLOC(dwLoopCounterNum);

+ // Make the shape of the loop similar to what C# compiler emits


The new shape seems to be missing the invocation of the trace helper at the end. E.g. if the invocation count is 2, the trace helper should be called 3 times. It is only called 2 times if I am reading the code correctly.

Fixed. Result codegen:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esijmp SHORT G_M000_IG04G_M000_IG03: ;; offset=0x000Dmovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG08movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesiG_M000_IG04: ;; offset=0x0024test dword ptr [(reloc 0x7ff84ea05210)],512jne SHORT G_M000_IG06G_M000_IG05: ;; offset=0x0030movsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03jmp SHORT G_M000_IG07G_M000_IG06: ;; offset=0x003Bmovrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG05G_M000_IG07: ;; offset=0x0047addrsp,40poprbxpoprsiretG_M000_IG08: ;; offset=0x004Ecall CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 84
JIT reorders the debugging block in front of the ret. Benchmark shows no regression. It's just a bit strange with the unconditional jumps.

huoyaoyuan · 2024-06-29T11:10:10Z

Closes#103958 .

Local benchmark result for Action<int> on x86:

Method	Job	Toolchain	Mean	Error	StdDev	Ratio
SingleArg	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	3.464 ns	0.0127 ns	0.0119 ns	0.95
SingleArg	Job-KBQPJV	\x86-main\corerun.exe	3.661 ns	0.0222 ns	0.0208 ns	1.00

ManyCast	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	8.188 ns	0.0944 ns	0.0883 ns	0.97
ManyCast	Job-KBQPJV	\x86-main\corerun.exe	8.483 ns	0.0888 ns	0.0831 ns	1.00

ManyArg_RetFPU	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	5.566 ns	0.0338 ns	0.0316 ns	0.96
ManyArg_RetFPU	Job-KBQPJV	\x86-main\corerun.exe	5.771 ns	0.0212 ns	0.0177 ns	1.00

huoyaoyuan · 2024-06-29T11:11:56Z

@EgorBot -intel -amd -arm64

usingBenchmarkDotNet.Attributes;usingSystem;namespaceBenchmarkGround{publicstructGCStruct{publicobjecta,b,c,d,e,f,h,g;}publicclassBench{privatereadonlyobjectobj=newobject();privatereadonlyGuidguid=Guid.NewGuid();privatereadonlyGCStructgcStruct=newGCStruct{a=newobject(),g=newobject()};privatereadonlyAction<int>singleArg=(Action<int>)delegate{}+delegate{};privatereadonlyAction<int>manyCast=(Action<int>)delegate{}+delegate{}+delegate{}+delegate{}+delegate{}+delegate{};privatereadonlyFunc<int,double,Guid,GCStruct,object,double>manyArg_RetFPU=(Func<int,double,Guid,GCStruct,object,double>)delegate{return123.456;}+delegate{return654.321;};[Benchmark]publicvoidSingleArg()=>singleArg(42);[Benchmark]publicvoidManyCast()=>manyCast(42);[Benchmark]publicdoubleManyArg_RetFPU()=>manyArg_RetFPU(42,123.0,guid,gcStruct,obj);}}

dotnet-policy-service · 2024-06-29T11:14:38Z

Tagging subscribers to this area: @mangod9
See info in area-owners.md if you want to be subscribed.

EgorBot · 2024-06-29T11:54:29Z

Benchmark results on Intel

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 8 logical and 4 physical cores
Job-FAGYWG : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
Job-LQQTSO : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	8.084 ns	0.0012 ns	1.00
SingleArg	PR	6.078 ns	0.0012 ns	0.75

ManyCast	Main	19.581 ns	0.0313 ns	1.00
ManyCast	PR	14.887 ns	0.1134 ns	0.76

ManyArg_RetFPU	Main	14.538 ns	0.0340 ns	1.00
ManyArg_RetFPU	PR	11.450 ns	0.0147 ns	0.79

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:24Z

Benchmark results on Arm64

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Unknown processor
Job-LOUVQC : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD
Job-TLYWZG : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	15.831 ns	0.0109 ns	1.00
SingleArg	PR	8.772 ns	0.0017 ns	0.55

ManyCast	Main	38.106 ns	0.0234 ns	1.00
ManyCast	PR	21.135 ns	0.0015 ns	0.55

ManyArg_RetFPU	Main	17.636 ns	0.0024 ns	1.00
ManyArg_RetFPU	PR	16.759 ns	0.0071 ns	0.95

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:44Z

Benchmark results on Amd

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
AMD EPYC 7763, 1 CPU, 8 logical and 4 physical cores
Job-DXSXUL : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2
Job-BIEGFU : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	13.008 ns	0.1016 ns	1.00
SingleArg	PR	6.490 ns	0.0071 ns	0.50

ManyCast	Main	100.460 ns	0.5200 ns	1.00
ManyCast	PR	18.849 ns	0.0302 ns	0.19

ManyArg_RetFPU	Main	14.358 ns	0.0464 ns	1.00
ManyArg_RetFPU	PR	12.682 ns	0.0120 ns	0.88

BDN_Artifacts.zip

jkotas · 2024-06-29T12:15:38Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


Suggested change
pCode->EmitBRTRUE(invokeTraceHelper);
pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
pCode->EmitLabel(invokeTraceHelper);
pCode->EmitLoadThis();
pCode->EmitLDLOC(dwLoopCounterNum);
pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);
pCode->EmitBRTRUE(invokeTraceHelper);
And move the debugging path to be after RET:
pCode->EmitRET(); #ifdef DEBUGGING_SUPPORTED // Emit debugging support at the end of the method for better perf pCode->EmitLabel(invokeTraceHelper); pCode->EmitLoadThis(); pCode->EmitLDLOC(dwLoopCounterNum); pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0); pCode->EmitBR(debuggerCheckEnd); #endif
This should be even better

That was exactly what I did locally, and resulted in exact same codegen with current, at least for x86. The compiled asm code block order did follow IL block order exactly.
@dotnet/jit-contrib Do you have any suggestion on this?

This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

Well normalizing the loop closer to a for loop results in about 5% improvement for ManyArg case, but 5% regression for ManyCast.

Codegen for x64 now:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esicmp qword ptr [rbx+0x30],0jle SHORT G_M000_IG05G_M000_IG03: ;; offset=0x0012test dword ptr [(reloc 0x7ff824c55210)],512jne SHORT G_M000_IG06G_M000_IG04: ;; offset=0x001Emovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG07movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesimovsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03G_M000_IG05: ;; offset=0x003Eaddrsp,40poprbxpoprsiretG_M000_IG06: ;; offset=0x0045movrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG04G_M000_IG07: ;; offset=0x0051call CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 87

jkotas

LGTM otherwise. Nice simplification!

jkotas · 2024-06-29T20:08:17Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

jkotas · 2024-06-30T14:59:13Z

 pCode->EmitLDC(0);
 pCode->EmitSTLOC(dwLoopCounterNum);

+ // Make the shape of the loop similar to what C# compiler emits


The new shape seems to be missing the invocation of the trace helper at the end. E.g. if the invocation count is 2, the trace helper should be called 3 times. It is only called 2 times if I am reading the code correctly.

Fixed. Result codegen:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esijmp SHORT G_M000_IG04G_M000_IG03: ;; offset=0x000Dmovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG08movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesiG_M000_IG04: ;; offset=0x0024test dword ptr [(reloc 0x7ff84ea05210)],512jne SHORT G_M000_IG06G_M000_IG05: ;; offset=0x0030movsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03jmp SHORT G_M000_IG07G_M000_IG06: ;; offset=0x003Bmovrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG05G_M000_IG07: ;; offset=0x0047addrsp,40poprbxpoprsiretG_M000_IG08: ;; offset=0x004Ecall CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 84
JIT reorders the debugging block in front of the ret. Benchmark shows no regression. It's just a bit strange with the unconditional jumps.

huoyaoyuan · 2024-06-29T11:10:10Z

Closes#103958 .

Local benchmark result for Action<int> on x86:

Method	Job	Toolchain	Mean	Error	StdDev	Ratio
SingleArg	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	3.464 ns	0.0127 ns	0.0119 ns	0.95
SingleArg	Job-KBQPJV	\x86-main\corerun.exe	3.661 ns	0.0222 ns	0.0208 ns	1.00

ManyCast	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	8.188 ns	0.0944 ns	0.0883 ns	0.97
ManyCast	Job-KBQPJV	\x86-main\corerun.exe	8.483 ns	0.0888 ns	0.0831 ns	1.00

ManyArg_RetFPU	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	5.566 ns	0.0338 ns	0.0316 ns	0.96
ManyArg_RetFPU	Job-KBQPJV	\x86-main\corerun.exe	5.771 ns	0.0212 ns	0.0177 ns	1.00

huoyaoyuan · 2024-06-29T11:11:56Z

@EgorBot -intel -amd -arm64

usingBenchmarkDotNet.Attributes;usingSystem;namespaceBenchmarkGround{publicstructGCStruct{publicobjecta,b,c,d,e,f,h,g;}publicclassBench{privatereadonlyobjectobj=newobject();privatereadonlyGuidguid=Guid.NewGuid();privatereadonlyGCStructgcStruct=newGCStruct{a=newobject(),g=newobject()};privatereadonlyAction<int>singleArg=(Action<int>)delegate{}+delegate{};privatereadonlyAction<int>manyCast=(Action<int>)delegate{}+delegate{}+delegate{}+delegate{}+delegate{}+delegate{};privatereadonlyFunc<int,double,Guid,GCStruct,object,double>manyArg_RetFPU=(Func<int,double,Guid,GCStruct,object,double>)delegate{return123.456;}+delegate{return654.321;};[Benchmark]publicvoidSingleArg()=>singleArg(42);[Benchmark]publicvoidManyCast()=>manyCast(42);[Benchmark]publicdoubleManyArg_RetFPU()=>manyArg_RetFPU(42,123.0,guid,gcStruct,obj);}}

dotnet-policy-service · 2024-06-29T11:14:38Z

Tagging subscribers to this area: @mangod9
See info in area-owners.md if you want to be subscribed.

EgorBot · 2024-06-29T11:54:29Z

Benchmark results on Intel

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 8 logical and 4 physical cores
Job-FAGYWG : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
Job-LQQTSO : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	8.084 ns	0.0012 ns	1.00
SingleArg	PR	6.078 ns	0.0012 ns	0.75

ManyCast	Main	19.581 ns	0.0313 ns	1.00
ManyCast	PR	14.887 ns	0.1134 ns	0.76

ManyArg_RetFPU	Main	14.538 ns	0.0340 ns	1.00
ManyArg_RetFPU	PR	11.450 ns	0.0147 ns	0.79

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:24Z

Benchmark results on Arm64

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Unknown processor
Job-LOUVQC : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD
Job-TLYWZG : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	15.831 ns	0.0109 ns	1.00
SingleArg	PR	8.772 ns	0.0017 ns	0.55

ManyCast	Main	38.106 ns	0.0234 ns	1.00
ManyCast	PR	21.135 ns	0.0015 ns	0.55

ManyArg_RetFPU	Main	17.636 ns	0.0024 ns	1.00
ManyArg_RetFPU	PR	16.759 ns	0.0071 ns	0.95

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:44Z

Benchmark results on Amd

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
AMD EPYC 7763, 1 CPU, 8 logical and 4 physical cores
Job-DXSXUL : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2
Job-BIEGFU : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	13.008 ns	0.1016 ns	1.00
SingleArg	PR	6.490 ns	0.0071 ns	0.50

ManyCast	Main	100.460 ns	0.5200 ns	1.00
ManyCast	PR	18.849 ns	0.0302 ns	0.19

ManyArg_RetFPU	Main	14.358 ns	0.0464 ns	1.00
ManyArg_RetFPU	PR	12.682 ns	0.0120 ns	0.88

BDN_Artifacts.zip

jkotas · 2024-06-29T12:15:38Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


Suggested change
pCode->EmitBRTRUE(invokeTraceHelper);
pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
pCode->EmitLabel(invokeTraceHelper);
pCode->EmitLoadThis();
pCode->EmitLDLOC(dwLoopCounterNum);
pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);
pCode->EmitBRTRUE(invokeTraceHelper);
And move the debugging path to be after RET:
pCode->EmitRET(); #ifdef DEBUGGING_SUPPORTED // Emit debugging support at the end of the method for better perf pCode->EmitLabel(invokeTraceHelper); pCode->EmitLoadThis(); pCode->EmitLDLOC(dwLoopCounterNum); pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0); pCode->EmitBR(debuggerCheckEnd); #endif
This should be even better

That was exactly what I did locally, and resulted in exact same codegen with current, at least for x86. The compiled asm code block order did follow IL block order exactly.
@dotnet/jit-contrib Do you have any suggestion on this?

This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

Well normalizing the loop closer to a for loop results in about 5% improvement for ManyArg case, but 5% regression for ManyCast.

Codegen for x64 now:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esicmp qword ptr [rbx+0x30],0jle SHORT G_M000_IG05G_M000_IG03: ;; offset=0x0012test dword ptr [(reloc 0x7ff824c55210)],512jne SHORT G_M000_IG06G_M000_IG04: ;; offset=0x001Emovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG07movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesimovsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03G_M000_IG05: ;; offset=0x003Eaddrsp,40poprbxpoprsiretG_M000_IG06: ;; offset=0x0045movrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG04G_M000_IG07: ;; offset=0x0051call CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 87

jkotas

LGTM otherwise. Nice simplification!

jkotas · 2024-06-29T20:08:17Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

jkotas · 2024-06-30T14:59:13Z

 pCode->EmitLDC(0);
 pCode->EmitSTLOC(dwLoopCounterNum);

+ // Make the shape of the loop similar to what C# compiler emits


The new shape seems to be missing the invocation of the trace helper at the end. E.g. if the invocation count is 2, the trace helper should be called 3 times. It is only called 2 times if I am reading the code correctly.

Fixed. Result codegen:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esijmp SHORT G_M000_IG04G_M000_IG03: ;; offset=0x000Dmovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG08movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesiG_M000_IG04: ;; offset=0x0024test dword ptr [(reloc 0x7ff84ea05210)],512jne SHORT G_M000_IG06G_M000_IG05: ;; offset=0x0030movsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03jmp SHORT G_M000_IG07G_M000_IG06: ;; offset=0x003Bmovrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG05G_M000_IG07: ;; offset=0x0047addrsp,40poprbxpoprsiretG_M000_IG08: ;; offset=0x004Ecall CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 84
JIT reorders the debugging block in front of the ret. Benchmark shows no regression. It's just a bit strange with the unconditional jumps.

huoyaoyuan · 2024-06-29T11:10:10Z

Closes#103958 .

Local benchmark result for Action<int> on x86:

Method	Job	Toolchain	Mean	Error	StdDev	Ratio
SingleArg	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	3.464 ns	0.0127 ns	0.0119 ns	0.95
SingleArg	Job-KBQPJV	\x86-main\corerun.exe	3.661 ns	0.0222 ns	0.0208 ns	1.00

ManyCast	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	8.188 ns	0.0944 ns	0.0883 ns	0.97
ManyCast	Job-KBQPJV	\x86-main\corerun.exe	8.483 ns	0.0888 ns	0.0831 ns	1.00

ManyArg_RetFPU	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	5.566 ns	0.0338 ns	0.0316 ns	0.96
ManyArg_RetFPU	Job-KBQPJV	\x86-main\corerun.exe	5.771 ns	0.0212 ns	0.0177 ns	1.00

huoyaoyuan · 2024-06-29T11:11:56Z

@EgorBot -intel -amd -arm64

usingBenchmarkDotNet.Attributes;usingSystem;namespaceBenchmarkGround{publicstructGCStruct{publicobjecta,b,c,d,e,f,h,g;}publicclassBench{privatereadonlyobjectobj=newobject();privatereadonlyGuidguid=Guid.NewGuid();privatereadonlyGCStructgcStruct=newGCStruct{a=newobject(),g=newobject()};privatereadonlyAction<int>singleArg=(Action<int>)delegate{}+delegate{};privatereadonlyAction<int>manyCast=(Action<int>)delegate{}+delegate{}+delegate{}+delegate{}+delegate{}+delegate{};privatereadonlyFunc<int,double,Guid,GCStruct,object,double>manyArg_RetFPU=(Func<int,double,Guid,GCStruct,object,double>)delegate{return123.456;}+delegate{return654.321;};[Benchmark]publicvoidSingleArg()=>singleArg(42);[Benchmark]publicvoidManyCast()=>manyCast(42);[Benchmark]publicdoubleManyArg_RetFPU()=>manyArg_RetFPU(42,123.0,guid,gcStruct,obj);}}

dotnet-policy-service · 2024-06-29T11:14:38Z

Tagging subscribers to this area: @mangod9
See info in area-owners.md if you want to be subscribed.

EgorBot · 2024-06-29T11:54:29Z

Benchmark results on Intel

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 8 logical and 4 physical cores
Job-FAGYWG : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
Job-LQQTSO : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	8.084 ns	0.0012 ns	1.00
SingleArg	PR	6.078 ns	0.0012 ns	0.75

ManyCast	Main	19.581 ns	0.0313 ns	1.00
ManyCast	PR	14.887 ns	0.1134 ns	0.76

ManyArg_RetFPU	Main	14.538 ns	0.0340 ns	1.00
ManyArg_RetFPU	PR	11.450 ns	0.0147 ns	0.79

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:24Z

Benchmark results on Arm64

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Unknown processor
Job-LOUVQC : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD
Job-TLYWZG : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	15.831 ns	0.0109 ns	1.00
SingleArg	PR	8.772 ns	0.0017 ns	0.55

ManyCast	Main	38.106 ns	0.0234 ns	1.00
ManyCast	PR	21.135 ns	0.0015 ns	0.55

ManyArg_RetFPU	Main	17.636 ns	0.0024 ns	1.00
ManyArg_RetFPU	PR	16.759 ns	0.0071 ns	0.95

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:44Z

Benchmark results on Amd

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
AMD EPYC 7763, 1 CPU, 8 logical and 4 physical cores
Job-DXSXUL : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2
Job-BIEGFU : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	13.008 ns	0.1016 ns	1.00
SingleArg	PR	6.490 ns	0.0071 ns	0.50

ManyCast	Main	100.460 ns	0.5200 ns	1.00
ManyCast	PR	18.849 ns	0.0302 ns	0.19

ManyArg_RetFPU	Main	14.358 ns	0.0464 ns	1.00
ManyArg_RetFPU	PR	12.682 ns	0.0120 ns	0.88

BDN_Artifacts.zip

jkotas · 2024-06-29T12:15:38Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


Suggested change
pCode->EmitBRTRUE(invokeTraceHelper);
pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
pCode->EmitLabel(invokeTraceHelper);
pCode->EmitLoadThis();
pCode->EmitLDLOC(dwLoopCounterNum);
pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);
pCode->EmitBRTRUE(invokeTraceHelper);
And move the debugging path to be after RET:
pCode->EmitRET(); #ifdef DEBUGGING_SUPPORTED // Emit debugging support at the end of the method for better perf pCode->EmitLabel(invokeTraceHelper); pCode->EmitLoadThis(); pCode->EmitLDLOC(dwLoopCounterNum); pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0); pCode->EmitBR(debuggerCheckEnd); #endif
This should be even better

That was exactly what I did locally, and resulted in exact same codegen with current, at least for x86. The compiled asm code block order did follow IL block order exactly.
@dotnet/jit-contrib Do you have any suggestion on this?

This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

Well normalizing the loop closer to a for loop results in about 5% improvement for ManyArg case, but 5% regression for ManyCast.

Codegen for x64 now:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esicmp qword ptr [rbx+0x30],0jle SHORT G_M000_IG05G_M000_IG03: ;; offset=0x0012test dword ptr [(reloc 0x7ff824c55210)],512jne SHORT G_M000_IG06G_M000_IG04: ;; offset=0x001Emovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG07movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesimovsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03G_M000_IG05: ;; offset=0x003Eaddrsp,40poprbxpoprsiretG_M000_IG06: ;; offset=0x0045movrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG04G_M000_IG07: ;; offset=0x0051call CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 87

jkotas

LGTM otherwise. Nice simplification!

jkotas · 2024-06-29T20:08:17Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

jkotas · 2024-06-30T14:59:13Z

 pCode->EmitLDC(0);
 pCode->EmitSTLOC(dwLoopCounterNum);

+ // Make the shape of the loop similar to what C# compiler emits


The new shape seems to be missing the invocation of the trace helper at the end. E.g. if the invocation count is 2, the trace helper should be called 3 times. It is only called 2 times if I am reading the code correctly.

Fixed. Result codegen:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esijmp SHORT G_M000_IG04G_M000_IG03: ;; offset=0x000Dmovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG08movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesiG_M000_IG04: ;; offset=0x0024test dword ptr [(reloc 0x7ff84ea05210)],512jne SHORT G_M000_IG06G_M000_IG05: ;; offset=0x0030movsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03jmp SHORT G_M000_IG07G_M000_IG06: ;; offset=0x003Bmovrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG05G_M000_IG07: ;; offset=0x0047addrsp,40poprbxpoprsiretG_M000_IG08: ;; offset=0x004Ecall CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 84
JIT reorders the debugging block in front of the ret. Benchmark shows no regression. It's just a bit strange with the unconditional jumps.

huoyaoyuan · 2024-06-29T11:10:10Z

Closes#103958 .

Local benchmark result for Action<int> on x86:

Method	Job	Toolchain	Mean	Error	StdDev	Ratio
SingleArg	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	3.464 ns	0.0127 ns	0.0119 ns	0.95
SingleArg	Job-KBQPJV	\x86-main\corerun.exe	3.661 ns	0.0222 ns	0.0208 ns	1.00

ManyCast	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	8.188 ns	0.0944 ns	0.0883 ns	0.97
ManyCast	Job-KBQPJV	\x86-main\corerun.exe	8.483 ns	0.0888 ns	0.0831 ns	1.00

ManyArg_RetFPU	Job-OSFVND	\x86-3-TuneBranchPrediction\corerun.exe	5.566 ns	0.0338 ns	0.0316 ns	0.96
ManyArg_RetFPU	Job-KBQPJV	\x86-main\corerun.exe	5.771 ns	0.0212 ns	0.0177 ns	1.00

huoyaoyuan · 2024-06-29T11:11:56Z

@EgorBot -intel -amd -arm64

usingBenchmarkDotNet.Attributes;usingSystem;namespaceBenchmarkGround{publicstructGCStruct{publicobjecta,b,c,d,e,f,h,g;}publicclassBench{privatereadonlyobjectobj=newobject();privatereadonlyGuidguid=Guid.NewGuid();privatereadonlyGCStructgcStruct=newGCStruct{a=newobject(),g=newobject()};privatereadonlyAction<int>singleArg=(Action<int>)delegate{}+delegate{};privatereadonlyAction<int>manyCast=(Action<int>)delegate{}+delegate{}+delegate{}+delegate{}+delegate{}+delegate{};privatereadonlyFunc<int,double,Guid,GCStruct,object,double>manyArg_RetFPU=(Func<int,double,Guid,GCStruct,object,double>)delegate{return123.456;}+delegate{return654.321;};[Benchmark]publicvoidSingleArg()=>singleArg(42);[Benchmark]publicvoidManyCast()=>manyCast(42);[Benchmark]publicdoubleManyArg_RetFPU()=>manyArg_RetFPU(42,123.0,guid,gcStruct,obj);}}

dotnet-policy-service · 2024-06-29T11:14:38Z

Tagging subscribers to this area: @mangod9
See info in area-owners.md if you want to be subscribed.

EgorBot · 2024-06-29T11:54:29Z

Benchmark results on Intel

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 8 logical and 4 physical cores
Job-FAGYWG : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
Job-LQQTSO : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	8.084 ns	0.0012 ns	1.00
SingleArg	PR	6.078 ns	0.0012 ns	0.75

ManyCast	Main	19.581 ns	0.0313 ns	1.00
ManyCast	PR	14.887 ns	0.1134 ns	0.76

ManyArg_RetFPU	Main	14.538 ns	0.0340 ns	1.00
ManyArg_RetFPU	PR	11.450 ns	0.0147 ns	0.79

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:24Z

Benchmark results on Arm64

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
Unknown processor
Job-LOUVQC : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD
Job-TLYWZG : .NET 9.0.0 (42.42.42.42424), Arm64 RyuJIT AdvSIMD

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	15.831 ns	0.0109 ns	1.00
SingleArg	PR	8.772 ns	0.0017 ns	0.55

ManyCast	Main	38.106 ns	0.0234 ns	1.00
ManyCast	PR	21.135 ns	0.0015 ns	0.55

ManyArg_RetFPU	Main	17.636 ns	0.0024 ns	1.00
ManyArg_RetFPU	PR	16.759 ns	0.0071 ns	0.95

BDN_Artifacts.zip

EgorBot · 2024-06-29T11:56:44Z

Benchmark results on Amd

BenchmarkDotNet v0.13.12, Ubuntu 22.04.4 LTS (Jammy Jellyfish)
AMD EPYC 7763, 1 CPU, 8 logical and 4 physical cores
Job-DXSXUL : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2
Job-BIEGFU : .NET 9.0.0 (42.42.42.42424), X64 RyuJIT AVX2

Method	Toolchain	Mean	Error	Ratio
SingleArg	Main	13.008 ns	0.1016 ns	1.00
SingleArg	PR	6.490 ns	0.0071 ns	0.50

ManyCast	Main	100.460 ns	0.5200 ns	1.00
ManyCast	PR	18.849 ns	0.0302 ns	0.19

ManyArg_RetFPU	Main	14.358 ns	0.0464 ns	1.00
ManyArg_RetFPU	PR	12.682 ns	0.0120 ns	0.88

BDN_Artifacts.zip

jkotas · 2024-06-29T12:15:38Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


Suggested change
pCode->EmitBRTRUE(invokeTraceHelper);
pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
pCode->EmitLabel(invokeTraceHelper);
pCode->EmitLoadThis();
pCode->EmitLDLOC(dwLoopCounterNum);
pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);
pCode->EmitBRTRUE(invokeTraceHelper);
And move the debugging path to be after RET:
pCode->EmitRET(); #ifdef DEBUGGING_SUPPORTED // Emit debugging support at the end of the method for better perf pCode->EmitLabel(invokeTraceHelper); pCode->EmitLoadThis(); pCode->EmitLDLOC(dwLoopCounterNum); pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0); pCode->EmitBR(debuggerCheckEnd); #endif
This should be even better

That was exactly what I did locally, and resulted in exact same codegen with current, at least for x86. The compiled asm code block order did follow IL block order exactly.
@dotnet/jit-contrib Do you have any suggestion on this?

This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

Well normalizing the loop closer to a for loop results in about 5% improvement for ManyArg case, but 5% regression for ManyCast.

Codegen for x64 now:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esicmp qword ptr [rbx+0x30],0jle SHORT G_M000_IG05G_M000_IG03: ;; offset=0x0012test dword ptr [(reloc 0x7ff824c55210)],512jne SHORT G_M000_IG06G_M000_IG04: ;; offset=0x001Emovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG07movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesimovsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03G_M000_IG05: ;; offset=0x003Eaddrsp,40poprbxpoprsiretG_M000_IG06: ;; offset=0x0045movrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG04G_M000_IG07: ;; offset=0x0051call CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 87

jkotas

LGTM otherwise. Nice simplification!

jkotas · 2024-06-29T20:08:17Z

+ pCode->EmitBRTRUE(invokeTraceHelper);
+ pCode->EmitBR(debuggerCheckEnd); // Tune branch prediction to prefer non-debugging path
+
+ pCode->EmitLabel(invokeTraceHelper);
+
 pCode->EmitLoadThis();
 pCode->EmitLDLOC(dwLoopCounterNum);
 pCode->EmitCALL(METHOD__STUBHELPERS__MULTICAST_DEBUGGER_TRACE_HELPER, 2, 0);


This code has atypical loop. It looks like the JIT tried to reorder the basic blocks to turn it a more regular loop. I am not sure whether there is anything to fix in the JIT (the JIT would have to have profile data to do better).
It may be still worth it to move TraceHelper call to be at the end in IL. It provides stronger hint about the desired code layout to the JIT and makes this optimization a bit less fragile.

jkotas · 2024-06-30T14:59:13Z

 pCode->EmitLDC(0);
 pCode->EmitSTLOC(dwLoopCounterNum);

+ // Make the shape of the loop similar to what C# compiler emits


The new shape seems to be missing the invocation of the trace helper at the end. E.g. if the invocation count is 2, the trace helper should be called 3 times. It is only called 2 times if I am reading the code correctly.

Fixed. Result codegen:
; Assembly listing for method System.Action:IL_STUB_MulticastDelegate_Invoke():this (FullOpts); Emitting BLENDED_CODE for X64 with AVX - Windows; FullOpts code; optimized code; optimized using Synthesized PGO; rsp based frame; partially interruptible; with Synthesized PGO: fgCalledCount is 100; No PGO dataG_M000_IG01: ;; offset=0x0000pushrsipushrbxsubrsp,40movrbx,rcxG_M000_IG02: ;; offset=0x0009xoresi,esijmp SHORT G_M000_IG04G_M000_IG03: ;; offset=0x000Dmovrcx, gword ptr [rbx+0x28]cmpesi, dword ptr [rcx+0x08]jae SHORT G_M000_IG08movrax, gword ptr [rcx+8*rsi+0x10]movrcx, gword ptr [rax+0x08]call[rax+0x18]System.Action:Invoke():thisincesiG_M000_IG04: ;; offset=0x0024test dword ptr [(reloc 0x7ff84ea05210)],512jne SHORT G_M000_IG06G_M000_IG05: ;; offset=0x0030movsxdrcx,esicmprcx, qword ptr [rbx+0x30]jl SHORT G_M000_IG03jmp SHORT G_M000_IG07G_M000_IG06: ;; offset=0x003Bmovrcx,rbxmovedx,esicall System.StubHelpers.StubHelpers:MulticastDebuggerTraceHelper(System.Object,int)jmp SHORT G_M000_IG05G_M000_IG07: ;; offset=0x0047addrsp,40poprbxpoprsiretG_M000_IG08: ;; offset=0x004Ecall CORINFO_HELP_RNGCHKFAILint3; Total bytes of code 84
JIT reorders the debugging block in front of the ret. Benchmark shows no regression. It's just a bit strange with the unconditional jumps.

huoyaoyuan added 7 commits June 29, 2024 15:40

Enable FEATURE_MULTICASTSTUB_AS_IL on win-x86
5ec5198

Unconditionally enable at use sites
a8225a4

Remove dead code
70c5e19

Delete feature flag
c2bbd66

Skip MulticastDebuggerTraceHelper when no debugger
49bd3b2

Reduce register pressure
e6ca8d5

Tune branch prediction
c50c39c

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ifdef format
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Typo
03e8811

Simplify register saving
0744c51

Normalize loop
a5ec68a

Hot-cold splitting
b492c11

jkotas reviewed Jun 30, 2024
View reviewed changes

Fix trace helper
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Enable FEATURE_MULTICASTSTUB_AS_IL on win-x86
5ec5198

Unconditionally enable at use sites
a8225a4

Remove dead code
70c5e19

Delete feature flag
c2bbd66

Skip MulticastDebuggerTraceHelper when no debugger
49bd3b2

Reduce register pressure
e6ca8d5

Tune branch prediction
c50c39c

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Fix trace helper
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Enable FEATURE_MULTICASTSTUB_AS_IL on win-x86
5ec5198

Unconditionally enable at use sites
a8225a4

Remove dead code
70c5e19

Delete feature flag
c2bbd66

Skip MulticastDebuggerTraceHelper when no debugger
49bd3b2

Reduce register pressure
e6ca8d5

Tune branch prediction
c50c39c

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Simplify register saving
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Normalize loop
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Hot-cold splitting
b492c11

jkotas reviewed Jun 30, 2024
View reviewed changes

Fix trace helper
4c83681

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Enable FEATURE_MULTICASTSTUB_AS_IL on win-x86
5ec5198

Unconditionally enable at use sites
a8225a4

Remove dead code
70c5e19

Delete feature flag
c2bbd66

Skip MulticastDebuggerTraceHelper when no debugger
49bd3b2

Reduce register pressure
e6ca8d5

Tune branch prediction
c50c39c

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Fix trace helper
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Enable FEATURE_MULTICASTSTUB_AS_IL on win-x86
5ec5198

Unconditionally enable at use sites
a8225a4

Remove dead code
70c5e19

Delete feature flag
c2bbd66

Skip MulticastDebuggerTraceHelper when no debugger
49bd3b2

Reduce register pressure
e6ca8d5

Tune branch prediction
c50c39c

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Enable FEATURE_MULTICASTSTUB_AS_IL on win-x86
5ec5198

Unconditionally enable at use sites
a8225a4

Remove dead code
70c5e19

Delete feature flag
c2bbd66

Skip MulticastDebuggerTraceHelper when no debugger
49bd3b2

Reduce register pressure
e6ca8d5

Tune branch prediction
c50c39c

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Simplify register saving
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Fix trace helper
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huoyaoyuan added 7 commits June 29, 2024 15:40

Enable FEATURE_MULTICASTSTUB_AS_IL on win-x86
5ec5198

Unconditionally enable at use sites
a8225a4

Remove dead code
70c5e19

Delete feature flag
c2bbd66

Skip MulticastDebuggerTraceHelper when no debugger
49bd3b2

Reduce register pressure
e6ca8d5

Tune branch prediction
c50c39c

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ifdef format
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Typo
03e8811

Simplify register saving
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Normalize loop
a5ec68a

Hot-cold splitting
b492c11

jkotas reviewed Jun 30, 2024
View reviewed changes

Fix trace helper
4c83681

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huoyaoyuan added 7 commits June 29, 2024 15:40

Enable FEATURE_MULTICASTSTUB_AS_IL on win-x86
5ec5198

Unconditionally enable at use sites
a8225a4

Remove dead code
70c5e19

Delete feature flag
c2bbd66

Skip MulticastDebuggerTraceHelper when no debugger
49bd3b2

Reduce register pressure
e6ca8d5

Tune branch prediction
c50c39c

ghost added the area-VM-coreclr label Jun 29, 2024

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ifdef format
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huoyaoyuan added 4 commits June 30, 2024 14:29

Typo
03e8811

Simplify register saving
0744c51

Normalize loop
a5ec68a

Hot-cold splitting
b492c11

jkotas reviewed Jun 30, 2024
View reviewed changes

Fix trace helper
4c83681

build-analysisBot mentioned this pull request Jun 30, 2024
Test failure: GC\\Scenarios\\FinalizeTimeout\\FinalizeTimeout\\FinalizeTimeout.cmd #103874
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Uh oh!

Conversation

huoyaoyuan commented Jun 29, 2024

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huoyaoyuan commented Jun 29, 2024

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huoyaoyuanJun 29, 2024•
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