JIT: consistently mark method table accesses as invariant #45854

AndyAyersMS · 2020-12-09T19:52:28Z

Introduce a new utility method to create the IR for method table access,
marking the resulting indir as invariant. This allows method table access
CSEs (which will be increasingly common with the advent of PGO-enabled
Guarded Devirtualization).

Add a workaround to assertion prop for method table to be able to see
through a CSE'd method table access.

Remove optimizer inhibitions related to colon cond, as there are no qmark
nodes around by this point.

Introduce a new utility method to create the IR for method table access, marking the resulting indir as invariant. This allows method table access CSEs (which will be increasingly common with the advent of PGO-enabled Guarded Devirtualization). Add a workaround to assertion prop for method table to be able to see through a CSE'd method table access. Remove optimizer inhibitions related to colon cond, as there are no qmark nodes around by this point.

AndyAyersMS · 2020-12-09T19:55:25Z

@briansull PTAL
cc @dotnet/jit-contrib

Relatively modest impact. Most regressions are extra CSEs. A couple of them are missed knock-on bounds checks caused by extra CSEs (see #45658). Large wins are in methods that have big chains of type tests guarding casts...

PMI CodeSize Diffs for System.Private.CoreLib.dll, framework assemblies for x64 default jit

Summary of Code Size diffs:
(Lower is better)

Total bytes of base: 50416759
Total bytes of diff: 50416678
Total bytes of delta: -81 (-0.00% of base)
    diff is an improvement.

Top file regressions (bytes):
         101 : Microsoft.CodeAnalysis.VisualBasic.dasm (0.00% of base)
          51 : System.Private.Xml.dasm (0.00% of base)
          33 : Microsoft.CodeAnalysis.CSharp.dasm (0.00% of base)
          30 : System.Collections.Immutable.dasm (0.00% of base)
          29 : System.Private.CoreLib.dasm (0.00% of base)
          20 : System.DirectoryServices.AccountManagement.dasm (0.01% of base)
          18 : System.Security.Cryptography.X509Certificates.dasm (0.01% of base)
          17 : System.Management.dasm (0.00% of base)
          10 : System.Configuration.ConfigurationManager.dasm (0.00% of base)
           9 : System.Data.Odbc.dasm (0.00% of base)
           6 : System.IO.FileSystem.Watcher.dasm (0.04% of base)
           6 : System.Resources.Extensions.dasm (0.02% of base)
           6 : Microsoft.CodeAnalysis.dasm (0.00% of base)
           6 : System.Resources.Writer.dasm (0.07% of base)
           5 : CommandLine.dasm (0.00% of base)
           3 : System.Reflection.Metadata.dasm (0.00% of base)
           3 : System.Text.Json.dasm (0.00% of base)
           2 : Microsoft.Diagnostics.Tracing.TraceEvent.dasm (0.00% of base)

Top file improvements (bytes):
        -294 : System.Data.Common.dasm (-0.02% of base)
         -71 : FSharp.Core.dasm (-0.00% of base)
         -34 : System.Security.AccessControl.dasm (-0.04% of base)
         -29 : System.DirectoryServices.dasm (-0.01% of base)
          -8 : System.Private.DataContractSerialization.dasm (-0.00% of base)

23 total files with Code Size differences (5 improved, 18 regressed), 245 unchanged.

Top method regressions (bytes):
         102 ( 4.10% of base) : System.Data.Common.dasm - <>c__DisplayClass16_0:<GetLinqDataView>b__0(DataRow):bool:this (7 methods)
          39 ( 2.78% of base) : System.Private.Xml.dasm - XmlQueryRuntime:ChangeTypeXsltArgument(XmlQueryType,Object,Type):Object:this
          39 ( 1.16% of base) : System.Private.Xml.dasm - XmlSerializationWriterCodeGen:WriteValue(Object):this
          30 ( 0.71% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Binder:BindFieldAndPropertyInitializers(SourceMemberContainerTypeSymbol,ImmutableArray`1,SynthesizedInteractiveInitializerMethod,DiagnosticBag):ImmutableArray`1
          30 ( 1.47% of base) : System.Collections.Immutable.dasm - ImmutableExtensions:TryCopyTo(IEnumerable`1,ref,int):bool (7 methods)
          29 ( 2.77% of base) : System.Private.CoreLib.dasm - Array:Copy(Array,int,Array,int,int,bool)
          21 ( 0.52% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Parser:ParseIfExpression():ExpressionSyntax:this
          17 ( 4.14% of base) : System.Data.Common.dasm - FunctionNode:Bind(DataTable,List`1):this
          15 ( 1.34% of base) : System.DirectoryServices.AccountManagement.dasm - AccountInfo:LoadValueIntoProperty(String,Object):this
          12 ( 0.36% of base) : Microsoft.CodeAnalysis.CSharp.dasm - SyntaxTreeSemanticModel:CreateMemberModel(CSharpSyntaxNode):MemberSemanticModel:this
          12 ( 1.33% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - VBSemanticModel:GetNamedArgumentSymbolInfo(IdentifierNameSyntax,CancellationToken):SymbolInfo:this
          11 ( 0.82% of base) : System.Management.dasm - ManagementObjectSearcher:Get(ManagementOperationObserver):this
          11 ( 0.72% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - SyntaxTreeSemanticModel:GetCrefOrNameAttributeReferenceSymbols(VisualBasicSyntaxNode,bool,byref):ImmutableArray`1:this
           9 ( 0.63% of base) : System.Data.Common.dasm - DbCommandBuilder:BuildCache(bool,DataRow,bool):this
           8 ( 1.42% of base) : System.Private.Xml.dasm - AllElementsContentValidator:ExpectedElements(ValidationState,bool):ArrayList:this
           7 ( 2.24% of base) : System.Data.Odbc.dasm - OdbcMetaDataFactory:DataTableFromDataReaderProcedureColumns(IDataReader,String,bool):DataTable:this
           7 ( 1.08% of base) : System.Private.Xml.dasm - AllElementsContentValidator:ExpectedParticles(ValidationState,bool,XmlSchemaSet):ArrayList:this
           6 ( 0.22% of base) : System.Configuration.ConfigurationManager.dasm - ConfigurationElement:Unmerge(ConfigurationElement,ConfigurationElement,int):this
           6 ( 0.52% of base) : System.IO.FileSystem.Watcher.dasm - FileSystemWatcher:WaitForChanged(int,int):WaitForChangedResult:this
           6 ( 0.38% of base) : System.Resources.Extensions.dasm - PreserializedResourceWriter:WriteValue(int,Object,BinaryWriter):this

Top method improvements (bytes):
        -239 (-21.28% of base) : System.Data.Common.dasm - BigIntegerStorage:ConvertToBigInteger(Object,IFormatProvider):BigInteger
        -138 (-4.89% of base) : System.Data.Common.dasm - XSDSchema:HandleElementColumn(XmlSchemaElement,DataTable,bool):this
         -62 (-31.47% of base) : FSharp.Core.dasm - Joint:GetHashCode(IEqualityComparer):int:this
         -58 (-6.33% of base) : System.Data.Common.dasm - ConstraintCollection:Add(Constraint,bool):this
         -34 (-0.76% of base) : System.Security.AccessControl.dasm - CommonAcl:RemoveQualifiedAces(SecurityIdentifier,int,int,ubyte,bool,int,Guid,Guid):bool:this
         -33 (-1.34% of base) : System.Private.Xml.dasm - Compiler:IsValidRestriction(XmlSchemaParticle,XmlSchemaParticle):bool:this
         -29 (-2.20% of base) : System.DirectoryServices.dasm - DirectoryServer:GetOutboundConnectionsHelper():ReplicationConnectionCollection:this
         -18 (-1.28% of base) : System.Private.Xml.dasm - ReflectionXmlSerializationWriter:WritePrimitiveValue(TypeDesc,Object,bool,byref):bool:this
          -8 (-2.27% of base) : System.Private.DataContractSerialization.dasm - SchemaExporter:ExportDataContract(DataContract):this
          -3 (-0.13% of base) : FSharp.Core.dasm - FSharpMap`2:Equals(Object):bool:this (7 methods)
          -3 (-0.16% of base) : FSharp.Core.dasm - FSharpMap`2:System.IComparable.CompareTo(Object):int:this (7 methods)
          -3 (-0.13% of base) : FSharp.Core.dasm - FSharpSet`1:Equals(Object):bool:this (7 methods)

Top method regressions (percentages):
          17 ( 4.14% of base) : System.Data.Common.dasm - FunctionNode:Bind(DataTable,List`1):this
         102 ( 4.10% of base) : System.Data.Common.dasm - <>c__DisplayClass16_0:<GetLinqDataView>b__0(DataRow):bool:this (7 methods)
          39 ( 2.78% of base) : System.Private.Xml.dasm - XmlQueryRuntime:ChangeTypeXsltArgument(XmlQueryType,Object,Type):Object:this
          29 ( 2.77% of base) : System.Private.CoreLib.dasm - Array:Copy(Array,int,Array,int,int,bool)
           3 ( 2.52% of base) : System.Private.Xml.dasm - XmlQueryTypeFactory:Serialize(BinaryWriter,XmlQueryType)
           3 ( 2.26% of base) : System.Security.Cryptography.X509Certificates.dasm - FindPal:ConfirmedCast(Object):int
           7 ( 2.24% of base) : System.Data.Odbc.dasm - OdbcMetaDataFactory:DataTableFromDataReaderProcedureColumns(IDataReader,String,bool):DataTable:this
           3 ( 2.24% of base) : System.Security.Cryptography.X509Certificates.dasm - FindPal:ConfirmedCast(Object):ubyte
           3 ( 2.24% of base) : System.Security.Cryptography.X509Certificates.dasm - FindPal:ConfirmedCast(Object):long
           3 ( 2.22% of base) : System.Security.Cryptography.X509Certificates.dasm - FindPal:ConfirmedCast(Object):short
           3 ( 2.17% of base) : System.Security.Cryptography.X509Certificates.dasm - FindPal:ConfirmedCast(Object):double
           3 ( 1.96% of base) : System.Security.Cryptography.X509Certificates.dasm - FindPal:ConfirmedCast(Object):Vector`1
          30 ( 1.47% of base) : System.Collections.Immutable.dasm - ImmutableExtensions:TryCopyTo(IEnumerable`1,ref,int):bool (7 methods)
           8 ( 1.42% of base) : System.Private.Xml.dasm - AllElementsContentValidator:ExpectedElements(ValidationState,bool):ArrayList:this
          15 ( 1.34% of base) : System.DirectoryServices.AccountManagement.dasm - AccountInfo:LoadValueIntoProperty(String,Object):this
          12 ( 1.33% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - VBSemanticModel:GetNamedArgumentSymbolInfo(IdentifierNameSyntax,CancellationToken):SymbolInfo:this
          39 ( 1.16% of base) : System.Private.Xml.dasm - XmlSerializationWriterCodeGen:WriteValue(Object):this
           7 ( 1.08% of base) : System.Private.Xml.dasm - AllElementsContentValidator:ExpectedParticles(ValidationState,bool,XmlSchemaSet):ArrayList:this
           3 ( 1.06% of base) : System.Text.Json.dasm - JsonConverter`1:TryWriteDataExtensionProperty(Utf8JsonWriter,__Canon,JsonSerializerOptions,byref):bool:this
           3 ( 0.87% of base) : Microsoft.CodeAnalysis.dasm - MetadataWriter:GetConstantTypeCode(Object):ubyte

Top method improvements (percentages):
         -62 (-31.47% of base) : FSharp.Core.dasm - Joint:GetHashCode(IEqualityComparer):int:this
        -239 (-21.28% of base) : System.Data.Common.dasm - BigIntegerStorage:ConvertToBigInteger(Object,IFormatProvider):BigInteger
         -58 (-6.33% of base) : System.Data.Common.dasm - ConstraintCollection:Add(Constraint,bool):this
        -138 (-4.89% of base) : System.Data.Common.dasm - XSDSchema:HandleElementColumn(XmlSchemaElement,DataTable,bool):this
          -8 (-2.27% of base) : System.Private.DataContractSerialization.dasm - SchemaExporter:ExportDataContract(DataContract):this
         -29 (-2.20% of base) : System.DirectoryServices.dasm - DirectoryServer:GetOutboundConnectionsHelper():ReplicationConnectionCollection:this
         -33 (-1.34% of base) : System.Private.Xml.dasm - Compiler:IsValidRestriction(XmlSchemaParticle,XmlSchemaParticle):bool:this
         -18 (-1.28% of base) : System.Private.Xml.dasm - ReflectionXmlSerializationWriter:WritePrimitiveValue(TypeDesc,Object,bool,byref):bool:this
         -34 (-0.76% of base) : System.Security.AccessControl.dasm - CommonAcl:RemoveQualifiedAces(SecurityIdentifier,int,int,ubyte,bool,int,Guid,Guid):bool:this
          -3 (-0.16% of base) : FSharp.Core.dasm - FSharpMap`2:System.IComparable.CompareTo(Object):int:this (7 methods)
          -3 (-0.13% of base) : FSharp.Core.dasm - FSharpMap`2:Equals(Object):bool:this (7 methods)
          -3 (-0.13% of base) : FSharp.Core.dasm - FSharpSet`1:Equals(Object):bool:this (7 methods)

65 total methods with Code Size differences (12 improved, 53 regressed), 258771 unchanged.

briansull · 2020-12-10T00:04:22Z

src/coreclr/jit/assertionprop.cpp

@@ -2111,11 +2114,6 @@ void Compiler::optAssertionGen(GenTree* tree)
 {
    tree->ClearAssertion();

-    if (tree->gtFlags & GTF_COLON_COND)


Is GTF_COLON_COND dead code that is being removed with this change?
Maybe change it to an assert here.

I don't believe that we can create an assertion that is predicated on a conditional

We remove QMARKS in morph, so perhaps this is too aggressive. I'll restore the bail out but only do it for local assertion prop.

briansull · 2020-12-10T00:29:16Z

src/coreclr/jit/gentree.h

+//    original tree, of not.
+//
+inline GenTree* GenTree::gtUnwrapCSE()
+{


While this is the format that we use for a CSE def there are several other places we will generate GT_COMMA's with this patterm.
Looking through the code base this function also is commonly used to generate an assignment to a new temp LclVar

GenTree* Compiler::fgInsertCommaFormTemp(GenTree** ppTree, CORINFO_CLASS_HANDLE structType /*= nullptr*/)

It doesn't have to be a CSE, it could be any value. I can rename the helper.

During global prop we have a mixture of rules that key off VNs and also look at IR shapes. In general we should just be able to use the VNs to figure most things out, but that doesn't happen consistently today. So in this case I need to find the original IR shape.

AndyAyersMS · 2020-12-11T19:15:45Z

@dotnet/jit-contrib ping

BruceForstall

You removed some GTF_EXCEPT bits; I presume you've proved those are unnecessary, despite the comments there saying "null pointer exception"?

briansull

Looks Good

AndyAyersMS · 2020-12-11T21:56:42Z

You removed some GTF_EXCEPT bits; I presume you've proved those are unnecessary,

The new helper goes through gtNewIndir which invokes SetIndirExceptionFlags which typically adds GTF_EXCEPT unless it can prove otherwise. So we actually see more GTF_EXCEPT bits get set with this change.

Dotnet-GitSync-Bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Dec 9, 2020

briansull reviewed Dec 10, 2020

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e904034

BruceForstall approved these changes Dec 11, 2020

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briansull approved these changes Dec 11, 2020

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AndyAyersMS merged commit bc12def into dotnet:master Dec 12, 2020

AndyAyersMS deleted the VtableIsInvariant branch December 12, 2020 01:40

AndyAyersMS mentioned this pull request Jan 7, 2021

Dynamic PGO #43618

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JIT: consistently mark method table accesses as invariant #45854

JIT: consistently mark method table accesses as invariant #45854

AndyAyersMS commented Dec 9, 2020

AndyAyersMS commented Dec 9, 2020

briansull Dec 10, 2020

AndyAyersMS Dec 10, 2020

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JIT: consistently mark method table accesses as invariant #45854

JIT: consistently mark method table accesses as invariant #45854

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