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JIT: GTF_GLOB_REF set unnecessarily on some local field accesses #856
Description
Activity
Prototype: NoGlobalFlagForFieldsOfLocals
Doesn't change things much...
;; x86 diffs Total bytes of diff: -25 (-0.00% of base) diff is an improvement. Top file improvements (bytes): -13 : System.Net.Ping.dasm (-0.10% of base) -6 : Microsoft.CodeAnalysis.VisualBasic.dasm (-0.00% of base) -6 : System.Security.Cryptography.X509Certificates.dasm (-0.00% of base) 3 total files with Code Size differences (3 improved, 0 regressed), 126 unchanged. Top method improvements (bytes): -13 (-5.46% of base) : System.Net.Ping.dasm - Ping:CreatePingReplyFromIcmp6EchoReply(Icmp6EchoReply,int,int):PingReply -6 (-0.31% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Symbol:ValidateAttributeUsage(VisualBasicAttributeData,AttributeSyntax,VisualBasicCompilation,int,DiagnosticBag,HashSet`1):bool:this -6 (-0.87% of base) : System.Security.Cryptography.X509Certificates.dasm - ChainPal:BuildChain(bool,ICertificatePal,X509Certificate2Collection,OidCollection,OidCollection,int,int,X509Certificate2Collection,int,DateTime,TimeSpan):ChainPal Top method improvements (percentages): -13 (-5.46% of base) : System.Net.Ping.dasm - Ping:CreatePingReplyFromIcmp6EchoReply(Icmp6EchoReply,int,int):PingReply -6 (-0.87% of base) : System.Security.Cryptography.X509Certificates.dasm - ChainPal:BuildChain(bool,ICertificatePal,X509Certificate2Collection,OidCollection,OidCollection,int,int,X509Certificate2Collection,int,DateTime,TimeSpan):ChainPal -6 (-0.31% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Symbol:ValidateAttributeUsage(VisualBasicAttributeData,AttributeSyntax,VisualBasicCompilation,int,DiagnosticBag,HashSet`1):bool:this 3 total methods with Code Size differences (3 improved, 0 regressed), 208456 unchanged. ;; x64 diffs Total bytes of diff: -327 (-0.00% of base) diff is an improvement. Top file regressions (bytes): 6 : System.Linq.Parallel.dasm (0.00% of base) Top file improvements (bytes): -73 : System.Private.CoreLib.dasm (-0.00% of base) -38 : Microsoft.CodeAnalysis.VisualBasic.dasm (-0.00% of base) -34 : Microsoft.CodeAnalysis.CSharp.dasm (-0.00% of base) -24 : System.Security.Cryptography.Algorithms.dasm (-0.01% of base) -22 : System.Private.Xml.dasm (-0.00% of base) -21 : System.Security.Cryptography.Cng.dasm (-0.01% of base) -16 : Microsoft.CodeAnalysis.dasm (-0.00% of base) -12 : System.Net.Http.dasm (-0.00% of base) -12 : System.Runtime.Numerics.dasm (-0.02% of base) -12 : System.Security.Cryptography.Csp.dasm (-0.02% of base) 21 total files with Code Size differences (20 improved, 1 regressed), 108 unchanged. Top method regressions (bytes): 7 ( 5.07% of base) : Microsoft.CodeAnalysis.CSharp.dasm - <>c:<UnwrapAlias>b__678_0(TypeSymbol,ValueTuple`3,bool):bool:this 6 ( 6.98% of base) : Microsoft.CodeAnalysis.CSharp.dasm - SynthesizedLambdaMethod:MakeName(String,DebugId,int,DebugId):String 6 ( 0.67% of base) : System.Linq.Parallel.dasm - ConcatKeyComparer:Compare(ConcatKey`2,ConcatKey`2):int:this (7 methods) 3 ( 1.02% of base) : Microsoft.CodeAnalysis.CSharp.dasm - AnonymousTypeManager:CreatePlaceholderTemplate(AnonymousTypeKey):AnonymousTypeTemplateSymbol:this 3 ( 1.72% of base) : System.Security.Cryptography.Cng.dasm - CngProperty:Equals(CngProperty):bool:this 2 ( 1.07% of base) : Microsoft.CodeAnalysis.CSharp.dasm - OverloadResolution:IsApplicable(BinaryOperatorSignature,BoundExpression,BoundExpression,byref):bool:this 2 ( 0.19% of base) : System.Security.Cryptography.Csp.dasm - CapiHelper:ToKeyBlob(RSAParameters):ref 1 ( 0.68% of base) : Microsoft.CodeAnalysis.CSharp.dasm - LambdaFrame:MakeName(SyntaxNode,DebugId,DebugId):String 1 ( 0.81% of base) : System.Data.Common.dasm - SqlStringStorage:Compare(SqlString,SqlString):int:this Top method improvements (bytes): -40 (-6.57% of base) : System.Private.CoreLib.dasm - ComActivator:GetClassFactoryForType(ComActivationContext):Object -24 (-2.83% of base) : System.Security.Cryptography.Algorithms.dasm - RSACng:ImportParameters(RSAParameters):this -24 (-2.83% of base) : System.Security.Cryptography.Cng.dasm - RSACng:ImportParameters(RSAParameters):this -22 (-4.37% of base) : System.Private.Xml.dasm - BigNumber:op_Explicit(BigNumber):double -16 (-4.98% of base) : System.Private.CoreLib.dasm - TupleExtensions:ToTuple(ValueTuple`1):Tuple`1 (7 methods) -15 (-1.78% of base) : Microsoft.CodeAnalysis.CSharp.dasm - OverloadResolution:InferMethodTypeArguments(MethodSymbol,ImmutableArray`1,AnalyzedArguments,EffectiveParameters,byref,byref):ImmutableArray`1:this -14 (-0.97% of base) : System.Security.Cryptography.Csp.dasm - CapiHelper:ToKeyBlob(DSAParameters):ref -12 (-5.00% of base) : System.Runtime.Numerics.dasm - BigInteger:op_Explicit(BigInteger):Decimal -11 (-9.73% of base) : Microsoft.CodeAnalysis.CSharp.dasm - LookupResult:SetFrom(SingleLookupResult):this -9 (-0.27% of base) : Microsoft.CodeAnalysis.dasm - ErrorLogger:GetPropertiesValue(Issue):Value:this Top method regressions (percentages): 6 ( 6.98% of base) : Microsoft.CodeAnalysis.CSharp.dasm - SynthesizedLambdaMethod:MakeName(String,DebugId,int,DebugId):String 7 ( 5.07% of base) : Microsoft.CodeAnalysis.CSharp.dasm - <>c:<UnwrapAlias>b__678_0(TypeSymbol,ValueTuple`3,bool):bool:this 3 ( 1.72% of base) : System.Security.Cryptography.Cng.dasm - CngProperty:Equals(CngProperty):bool:this 2 ( 1.07% of base) : Microsoft.CodeAnalysis.CSharp.dasm - OverloadResolution:IsApplicable(BinaryOperatorSignature,BoundExpression,BoundExpression,byref):bool:this 3 ( 1.02% of base) : Microsoft.CodeAnalysis.CSharp.dasm - AnonymousTypeManager:CreatePlaceholderTemplate(AnonymousTypeKey):AnonymousTypeTemplateSymbol:this 1 ( 0.81% of base) : System.Data.Common.dasm - SqlStringStorage:Compare(SqlString,SqlString):int:this 1 ( 0.68% of base) : Microsoft.CodeAnalysis.CSharp.dasm - LambdaFrame:MakeName(SyntaxNode,DebugId,DebugId):String 6 ( 0.67% of base) : System.Linq.Parallel.dasm - ConcatKeyComparer:Compare(ConcatKey`2,ConcatKey`2):int:this (7 methods) 2 ( 0.19% of base) : System.Security.Cryptography.Csp.dasm - CapiHelper:ToKeyBlob(RSAParameters):ref Top method improvements (percentages): -2 (-25.00% of base) : Microsoft.Diagnostics.Tracing.TraceEvent.dasm - <>c:<.cctor>b__186_1(int,EventsToCodeAddressIndex):int:this -2 (-18.18% of base) : System.Private.CoreLib.dasm - Char8:CompareTo(Char8):int:this -3 (-16.67% of base) : Microsoft.Diagnostics.Tracing.TraceEvent.dasm - <>c__DisplayClass14_0:<GetValue>b__0(CtfNamedRange):bool:this -2 (-14.29% of base) : Microsoft.Diagnostics.Tracing.TraceEvent.dasm - <>c:<.cctor>b__186_0(int,EventsToStackIndex):int:this -3 (-11.11% of base) : Microsoft.CodeAnalysis.CSharp.dasm - <>c:<Analyze>b__4_0(VariableIdentifier):bool:this -11 (-9.73% of base) : Microsoft.CodeAnalysis.CSharp.dasm - LookupResult:SetFrom(SingleLookupResult):this -8 (-8.25% of base) : System.Diagnostics.Process.dasm - <>c:<GetPerformanceCounterLib>b__14_1(ValueTuple`2):PerformanceCounterLib:this -6 (-8.00% of base) : System.Text.RegularExpressions.dasm - SingleRangeComparer:Compare(SingleRange,SingleRange):int:this (3 methods) -2 (-6.67% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - _Closure$__:_Lambda$__16-9(TriviaKey,SyntaxTrivia):bool:this -40 (-6.57% of base) : System.Private.CoreLib.dasm - ComActivator:GetClassFactoryForType(ComActivationContext):Object 59 total methods with Code Size differences (50 improved, 9 regressed), 208874 unchanged.Prototype: NoGlobalFlagForFieldsOfLocals
FWIW I suspect that my current crusade against
GT_ADDRwill take care of this eventually.LocalAddressVisitorwill handle more and more cases of "indirect access to a local" or "address of a local" and in the process clearGTF_GLOB_REFso at least we'll reach global morph without such issues. Remains to be seen when I'll be able to take care of the part beforeLocalAddressVisitor...Also, if a variable is address exposed, morph will add back
GTF_GLOB_REFand in doing so it will again "poison" all trees containingADDR(LCL_VAR). The only safe way to avoidGTF_GLOB_REFin such cases is to useLCL_VAR_ADDR.Would be nice to get this right early and have one utility we can call. Playing around with making
IsLocalAddrExprbe that utility, deprecatingimpIsAddressInLocaland updatingfgIsIndrofAddrOfLocal.Need to look around and see if there are any other ad-hoc classifiers.
Playing around with making IsLocalAddrExpr be that utility, deprecating impIsAddressInLocal and updating fgIsIndrofAddrOfLocal.
The proper way to do this is to get rid of all that stuff, not updating it.
@mikedn how do you see the importer handling these cases?
how do you see the importer handling these cases?
- Import
ldlocaandldargaasLCL_VAR_ADDR - Fold
ldfldaandldfldofLCL_VAR_ADDRon the fly to produceLCL_FLD_ADDRandLCL_FLDrespectively. Local field access doesn't suffer from the complexities associated with non-local field access (null checks, side effects,fgUnwrapProxyetc.) so there's very little reason to defer this to global morph. This kind of deferral might be the elegant thing to do in a normal compiler but for a JIT is overkill both throughput and complexity wise. - Maybe fold other trees on the fly, such as
ldind(LCL_VAR_ADDR)oradd(LCL_VAR_ADDR, 4). Not clear how common these are to worth the extra complexity.
- Import
- added a commit that references this issue
on Apr 9, 2021 @SingleAccretion perhaps you've already addressed this one?
No, not yet at least.
It should get addressed with the refactoring of
FIELDintoFIELD_ADDRthat I am yet to start working on.- added a commit that references this issue
on Jul 7, 2022 Still relevant.
- added a commit that references this issue
on Apr 7, 2023 - ghost locked as resolved and limited conversation to collaborators
on May 8, 2023
In particular, for address of a field.
We also should clarify or remove the x64/arm64 conservatism around implicit byref struct params.
See notes over in #845.
category:implementation
theme:ir
skill-level:expert
cost:medium