JIT: save generics context for late devirtualization #63420

AndyAyersMS · 2022-01-05T23:46:32Z

If we have a non-inline candidate call with generics context, save
the context so it's available for late devirtualization.

Fixes a missing devirtualization reported in #63283.

I am deliberately leaving LateDevirtualizationInfo more general than
necessary as it may serve as a jumping-off point for enabling late
inlining.

If we have a non-inline candidate call with generics context, save the context so it's available for late devirtualization. Fixes a missing devirtualization reported in dotnet#63283. I am deliberately leaving `LateDevirtualizationInfo` more general than necessary as it may serve as a jumping-off point for enabling late inlining.

ghost · 2022-01-05T23:46:39Z

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Issue Details

If we have a non-inline candidate call with generics context, save
the context so it's available for late devirtualization.

Fixes a missing devirtualization reported in #63283.

I am deliberately leaving LateDevirtualizationInfo more general than
necessary as it may serve as a jumping-off point for enabling late
inlining.

Author:	AndyAyersMS
Assignees:	-
Labels:	`area-CodeGen-coreclr`
Milestone:	-

AndyAyersMS · 2022-01-05T23:49:33Z

cc @dotnet/jit-contrib

SPMI diffs not interesting as any method that would benefit from new behavior gets a missing info error (~176K of them all told).

PMI diffs show a few hundred improvements. Regressions are from extra CSEs/spills.

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: 62817061
Total bytes of diff: 62813898
Total bytes of delta: -3163 (-0.01 % of base)
Total relative delta: -5.06
    diff is an improvement.
    relative diff is an improvement.


Top file improvements (bytes):
        -841 : System.Linq.Parallel.dasm (-0.04% of base)
        -534 : Microsoft.CodeAnalysis.dasm (-0.03% of base)
        -246 : Microsoft.Diagnostics.Tracing.TraceEvent.dasm (-0.01% of base)
        -200 : Microsoft.CodeAnalysis.VisualBasic.dasm (-0.00% of base)
        -194 : Microsoft.CodeAnalysis.CSharp.dasm (-0.00% of base)
        -130 : System.Private.Xml.dasm (-0.00% of base)
         -98 : System.Private.Xml.Linq.dasm (-0.05% of base)
         -92 : System.ComponentModel.Composition.dasm (-0.02% of base)
         -78 : Newtonsoft.Json.dasm (-0.01% of base)
         -70 : System.Private.CoreLib.dasm (-0.00% of base)
         -56 : System.Text.RegularExpressions.dasm (-0.01% of base)
         -54 : System.Security.Principal.Windows.dasm (-0.09% of base)
         -49 : System.Threading.Tasks.Dataflow.dasm (-0.00% of base)
         -35 : xunit.execution.dotnet.dasm (-0.01% of base)
         -28 : xunit.assert.dasm (-0.02% of base)
         -28 : System.Net.Http.dasm (-0.00% of base)
         -27 : System.Speech.dasm (-0.01% of base)
         -25 : Microsoft.Extensions.Caching.Memory.dasm (-0.11% of base)
         -21 : Microsoft.Extensions.DependencyModel.dasm (-0.03% of base)
         -21 : xunit.console.dasm (-0.02% of base)

50 total files with Code Size differences (50 improved, 0 regressed), 223 unchanged.

Top method regressions (bytes):
          57 ( 3.78% of base) : System.Private.Xml.dasm - XmlILVisitor:Function(QilFunction):this
           8 ( 0.14% of base) : System.Private.Xml.dasm - QilGenerator:PrecompileProtoTemplatesHeaders():this
           4 ( 0.33% of base) : System.Private.Xml.dasm - QilGenerator:GetNsVar(QilList):QilIterator:this
           2 ( 0.12% of base) : System.Private.Xml.dasm - XmlILVisitor:VisitSort(QilLoop):QilNode:this
           1 ( 0.03% of base) : System.Private.Xml.dasm - XmlILVisitor:VisitGlobalValues(QilList):this

Top method improvements (bytes):
         -91 (-13.70% of base) : System.Linq.Parallel.dasm - NullableDoubleMinMaxAggregationOperator:InternalAggregate(byref):Nullable`1:this
         -56 (-2.50% of base) : System.Linq.Parallel.dasm - AnyAllSearchOperator`1:Aggregate():bool:this (8 methods)
         -56 (-2.61% of base) : System.Linq.Parallel.dasm - ContainsSearchOperator`1:Aggregate():bool:this (8 methods)
         -56 (-2.90% of base) : System.Linq.Parallel.dasm - CountAggregationOperator`1:InternalAggregate(byref):int:this (8 methods)
         -56 (-2.88% of base) : System.Linq.Parallel.dasm - LongCountAggregationOperator`1:InternalAggregate(byref):long:this (8 methods)
         -49 (-1.03% of base) : System.Linq.Parallel.dasm - ElementAtQueryOperator`1:Aggregate(byref,bool):bool:this (8 methods)
         -49 (-1.55% of base) : Microsoft.CodeAnalysis.dasm - EnumerableExtensions:ToDictionary(IEnumerable`1,Func`2,IEqualityComparer`1):Dictionary`2 (8 methods)
         -49 (-7.72% of base) : Microsoft.CodeAnalysis.dasm - ImmutableSetWithInsertionOrder`1:GetEnumerator():IEnumerator`1:this (8 methods)
         -49 (-7.72% of base) : Microsoft.CodeAnalysis.dasm - ImmutableSetWithInsertionOrder`1:System.Collections.IEnumerable.GetEnumerator():IEnumerator:this (8 methods)
         -49 (-2.04% of base) : System.Threading.Tasks.Dataflow.dasm - SingleProducerSingleConsumerQueue_DebugView:get_Items():ref:this (8 methods)
         -49 (-2.21% of base) : Microsoft.CodeAnalysis.dasm - UnionCollection`1:GetEnumerator():IEnumerator`1:this (8 methods)
         -42 (-0.24% of base) : System.Text.RegularExpressions.dasm - <EnumeratePaths>d__28:MoveNext():bool:this (8 methods)
         -42 (-0.72% of base) : Microsoft.CodeAnalysis.dasm - AnalyzerDriver`1:get_CodeBlockStartActionsByAnalyzer():ImmutableDictionary`2:this (6 methods)
         -42 (-0.70% of base) : Microsoft.CodeAnalysis.dasm - AnalyzerDriver`1:get_NodeActionsByAnalyzerAndKind():ImmutableDictionary`2:this (6 methods)
         -42 (-0.90% of base) : Microsoft.CodeAnalysis.dasm - AnalyzerDriver`1:GetCodeBlockActionsByAnalyzer(byref,ImmutableArray`1):ImmutableDictionary`2 (6 methods)
         -40 (-0.96% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - StateMachineRewriter`1:CreateNonReusableLocalProxies(Result,byref):this (8 methods)
         -40 (-2.84% of base) : System.Private.Xml.dasm - XmlILVisitor:VisitStrConcat(QilStrConcat):QilNode:this
         -31 (-2.40% of base) : Microsoft.CodeAnalysis.CSharp.dasm - ClsComplianceChecker:CheckForAttributeWithArrayArgumentInternal(ImmutableArray`1):this
         -29 (-5.68% of base) : System.Linq.Parallel.dasm - NullableLongMinMaxAggregationOperator:InternalAggregate(byref):Nullable`1:this
         -26 (-3.24% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - MethodCompiler:CompileSynthesizedMethods(PrivateImplementationDetails):this

Top method regressions (percentages):
          57 ( 3.78% of base) : System.Private.Xml.dasm - XmlILVisitor:Function(QilFunction):this
           4 ( 0.33% of base) : System.Private.Xml.dasm - QilGenerator:GetNsVar(QilList):QilIterator:this
           8 ( 0.14% of base) : System.Private.Xml.dasm - QilGenerator:PrecompileProtoTemplatesHeaders():this
           2 ( 0.12% of base) : System.Private.Xml.dasm - XmlILVisitor:VisitSort(QilLoop):QilNode:this
           1 ( 0.03% of base) : System.Private.Xml.dasm - XmlILVisitor:VisitGlobalValues(QilList):this

Top method improvements (percentages):
         -91 (-13.70% of base) : System.Linq.Parallel.dasm - NullableDoubleMinMaxAggregationOperator:InternalAggregate(byref):Nullable`1:this
          -7 (-9.21% of base) : System.Private.CoreLib.dasm - CounterPayload:GetEnumerator():IEnumerator`1:this
          -7 (-9.21% of base) : System.Private.CoreLib.dasm - CounterPayload:System.Collections.IEnumerable.GetEnumerator():IEnumerator:this
          -7 (-9.21% of base) : Microsoft.Diagnostics.Tracing.TraceEvent.dasm - Histogram:GetEnumerator():IEnumerator`1:this
          -7 (-9.21% of base) : System.Private.CoreLib.dasm - IncrementingCounterPayload:GetEnumerator():IEnumerator`1:this
          -7 (-9.21% of base) : System.Private.CoreLib.dasm - IncrementingCounterPayload:System.Collections.IEnumerable.GetEnumerator():IEnumerator:this
         -49 (-7.72% of base) : Microsoft.CodeAnalysis.dasm - ImmutableSetWithInsertionOrder`1:GetEnumerator():IEnumerator`1:this (8 methods)
         -49 (-7.72% of base) : Microsoft.CodeAnalysis.dasm - ImmutableSetWithInsertionOrder`1:System.Collections.IEnumerable.GetEnumerator():IEnumerator:this (8 methods)
         -25 (-6.33% of base) : Microsoft.CodeAnalysis.CSharp.dasm - MethodCompiler:CompileSynthesizedMethods(PrivateImplementationDetails,DiagnosticBag):this
         -29 (-5.68% of base) : System.Linq.Parallel.dasm - NullableLongMinMaxAggregationOperator:InternalAggregate(byref):Nullable`1:this
         -11 (-5.21% of base) : System.Reflection.MetadataLoadContext.dasm - MetadataLoadContext:Dispose(bool):this
         -21 (-5.10% of base) : System.Linq.Parallel.dasm - NullableFloatAverageAggregationOperator:InternalAggregate(byref):Nullable`1:this
         -21 (-5.02% of base) : System.Linq.Parallel.dasm - IntMinMaxAggregationOperator:InternalAggregate(byref):int:this
         -21 (-4.98% of base) : System.Linq.Parallel.dasm - NullableDoubleAverageAggregationOperator:InternalAggregate(byref):Nullable`1:this
         -21 (-4.94% of base) : System.Linq.Parallel.dasm - LongMinMaxAggregationOperator:InternalAggregate(byref):long:this
         -21 (-4.93% of base) : System.Linq.Parallel.dasm - NullableIntAverageAggregationOperator:InternalAggregate(byref):Nullable`1:this
         -21 (-4.93% of base) : System.Linq.Parallel.dasm - NullableLongAverageAggregationOperator:InternalAggregate(byref):Nullable`1:this
         -21 (-4.85% of base) : System.Linq.Parallel.dasm - NullableIntMinMaxAggregationOperator:InternalAggregate(byref):Nullable`1:this
         -11 (-4.56% of base) : System.ComponentModel.Composition.dasm - AggregateCatalog:GetEnumerator():IEnumerator`1:this
         -11 (-4.56% of base) : System.ComponentModel.Composition.dasm - DirectoryCatalog:GetEnumerator():IEnumerator`1:this

299 total methods with Code Size differences (294 improved, 5 regressed), 278692 unchanged.

Codegen for Cmp from #63283 is now

; Assembly listing for method C:Cmp(System.String):int
; Emitting BLENDED_CODE for X64 CPU with AVX - Windows
; optimized code
; rsp based frame
; fully interruptible
; No PGO data
; 0 inlinees with PGO data; 1 single block inlinees; 0 inlinees without PGO data
; Final local variable assignments
;
;  V00 arg0         [V00,T00] (  3,  3   )     ref  ->  rcx         class-hnd single-def
;# V01 OutArgs      [V01    ] (  1,  1   )  lclBlk ( 0) [rsp+00H]   "OutgoingArgSpace"
;
; Lcl frame size = 0

G_M25227_IG01:              ;; offset=0000H
						;; bbWeight=1    PerfScore 0.00
G_M25227_IG02:              ;; offset=0000H
       48BA2030009811020000 mov      rdx, 0x21198003020      ; ""
       488B12               mov      rdx, gword ptr [rdx]
       3909                 cmp      dword ptr [rcx], ecx
						;; bbWeight=1    PerfScore 5.25
G_M25227_IG03:              ;; offset=000FH
       FF25B3A0ACFF         tail.jmp [System.String:CompareTo(System.String):int:this]
						;; bbWeight=1    PerfScore 2.00

AndyAyersMS · 2022-01-06T01:52:40Z

Seeing some failures where GTF_CALL_M_LATE_DEVIRT is set but the LateDevirtualizationInfo is null. Debugging now.

AndyAyersMS · 2022-01-06T03:17:01Z

Updated to copy the union field --we can clone GTF_CALL_M_LATE_DEVIRT calls and the data they refer to is immutable.

We can't safely clone inline or gdv candidates this way, but we don't do that now.

AndyAyersMS · 2022-01-06T18:54:16Z

@EgorBo can you take a look?

EgorBo · 2022-01-06T20:19:28Z

src/coreclr/jit/importer.cpp

+                {
+                    JITDUMP("\nSaving context %p for call [%06u]\n", exactContextHnd, dspTreeID(origCall));
+                    origCall->gtCallMoreFlags |= GTF_CALL_M_LATE_DEVIRT;
+                    LateDevirtualizationInfo* const info = new (this, CMK_Inlining) LateDevirtualizationInfo;


Are you planning to add more fields to LateDevirtualizationInfo? because for now it looks like allocation is not needed

Maybe? That's what I meant by

I am deliberately leaving LateDevirtualizationInfo more general than
necessary as it may serve as a jumping-off point for enabling late inlining.

EgorBo · 2022-01-06T20:20:03Z

src/coreclr/jit/fginline.cpp

            const bool             isLateDevirtualization = true;
-            bool explicitTailCall = (call->AsCall()->gtCallMoreFlags & GTF_CALL_M_EXPLICIT_TAILCALL) != 0;
+            const bool explicitTailCall = (call->AsCall()->gtCallMoreFlags & GTF_CALL_M_EXPLICIT_TAILCALL) != 0;


just a nit: there is IsTailPrefixedCall()

Yep, will change it over. Also, we already know call is GenTreeCall*.

EgorBo · 2022-01-20T16:12:27Z

Improvement on win-arm64 dotnet/perf-autofiling-issues#2978

dotnet-issue-labeler bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Jan 5, 2022

ghost assigned AndyAyersMS Jan 5, 2022

copy the union field

c32ef09

runfoapp bot mentioned this pull request Jan 6, 2022

Test failure: System.Security.Cryptography.X509Certificates.Tests.CertificateCreation.CertificateRequestChainTests/CreateChain_Hybrid #25979

Closed

AndyAyersMS mentioned this pull request Jan 6, 2022

JIT cannot devirtualize interface call in trivial cases #63283

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EgorBo reviewed Jan 6, 2022

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EgorBo approved these changes Jan 6, 2022

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64ed1f9

AndyAyersMS merged commit a0220fd into dotnet:main Jan 6, 2022

This was referenced Jan 11, 2022

[Perf] Changes at 1/7/2022 3:19:13 AM dotnet/perf-autofiling-issues#2811

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[Perf] Changes at 1/7/2022 3:19:13 AM dotnet/perf-autofiling-issues#2837

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JulieLeeMSFT mentioned this pull request Jan 25, 2022

What's new in .NET 7 Preview 1 [WIP] dotnet/core#7106

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JIT: save generics context for late devirtualization #63420

JIT: save generics context for late devirtualization #63420

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EgorBo commented Jan 20, 2022 •

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JIT: save generics context for late devirtualization #63420

JIT: save generics context for late devirtualization #63420

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