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JIT: heuristics in optInvertWhileLoop may be overly conservative #6569

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JosephTremoulet opened this issue Aug 26, 2016 · 2 comments
Closed

JIT: heuristics in optInvertWhileLoop may be overly conservative #6569

JosephTremoulet opened this issue Aug 26, 2016 · 2 comments
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@BruceForstall
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area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI enhancement Product code improvement that does NOT require public API changes/additions optimization tenet-performance Performance related issue
Milestone
6.0.0

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@JosephTremoulet
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For example, the loop in method Fit from benchmark Puzzle gets rejected as too costly, causing loop hoisting etc. not to run on it, but it's a good candidate for such optimizations and Jit64 performed them on it:

    private bool Fit(int i, int j)
    {
        for (int k = 0; k <= _pieceMax[i]; k++)
        {
            if (_p[i][k])
            {
                if (_puzzle[j + k])
                {
                    return false;
                }
            }
        }

        return true;
    }

There's already special consideration for loop conditions that involve shared static helpers; maybe similar treatment should be applied to loop conditions involving arrLen operators.

In this particular case, getting past the heuristic would enable hoisting the load of _p and the sign extension of i from the loop, but hoisting more of _p[i] (like the length of _p, the bounds-check, and/or the whole load) is blocked by #6554.

category:cq
theme:loop-opt
skill-level:expert
cost:medium
@msftgits msftgits transferred this issue from dotnet/coreclr Jan 31, 2020
@msftgits msftgits added this to the Future milestone Jan 31, 2020
@AndyAyersMS
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See also notes/prototype in #780. Tried extending the cloning to cover multiple statements, etc.

@BruceForstall BruceForstall mentioned this issue Oct 17, 2020
Closed
25 tasks
@BruceForstall BruceForstall added the JitUntriaged CLR JIT issues needing additional triage label Oct 28, 2020
@BruceForstall BruceForstall modified the milestones: Future, 6.0.0 Jan 15, 2021
@BruceForstall BruceForstall removed the JitUntriaged CLR JIT issues needing additional triage label Jan 15, 2021
@JulieLeeMSFT JulieLeeMSFT added the needs-further-triage Issue has been initially triaged, but needs deeper consideration or reconsideration label Mar 23, 2021
@BruceForstall BruceForstall changed the title JIT: heuristics in fgOptWhileLoop may be overly conservative JIT: heuristics in optInvertWhileLoop may be overly conservative Mar 30, 2021
@BruceForstall BruceForstall added preview and removed needs-further-triage Issue has been initially triaged, but needs deeper consideration or reconsideration labels Apr 6, 2021
@BruceForstall BruceForstall mentioned this issue Apr 9, 2021
Merged
BruceForstall added a commit to BruceForstall/runtime that referenced this issue Apr 13, 2021
@BruceForstall
Generalize loop inversion
9fb0c94 
Starting with an experimental branch from @AndyAyersMS,
generalize the loop inversion `optInvertWhileLoop` code
to consider duplicating an entire conditional block, not
just a conditional block that contains exactly one JTRUE
tree. Since the JTRUE itself wasn't considered before in
the costing, bump up the maximum cost allowed by 2 to account
for that. (Note that there is a lot of room here for tuning
the cost/benefit analysis.)

Additionally, the code already bumped the allowed cost if the
condition tree contained calls to a shared static helper. Add
another boost if the tree contains array.Length expressions,
which are likely to be CSE'ed.

Loop inversion by itself doesn't buy much, but our downstream
phases, like natural loop recognition, loop hoisting, and loop
cloning, depend on an inverted loop structure with a zero trip
test.

There are many diffs, typically size regressions because we
are duplicating code. Some notable cases:
1. BenchI Puzzle. This was a motivating example, from dotnet#6569.
It ends up with multiple new CSEs and BDN shows a 24% run-time
improvement.
2. RegexRedux_5 and ReverseComplement_1 also report faster
3. On the contrary, FannkuchRedux_5 reports 23% slower. It appears
we create fewer CSEs and end up with a couple more instructions
inside some tight loops.
4. Other things typically seen in diffs: (a) removed null and
bounds checks, (b) additional CSEs, (c) loop alignment kicks in.

The loop matching at the stage inversion runs is lexical and very
simplistic, as it is before natural loop recognition. As a result,
for some loops, like multiple-condition `while` loops (e.g.,
`while (--digits >= 0 || value != 0)` in
`System.Number:UInt32ToDecChars`), the inversion ends up creating
some pretty weird flow. (That's actually not new to this change.)

I added a `COMPlus_JitDoLoopInversion` config to allow turning
off the phase to do experiments.

Here are the diffs for SPMI on the benchmarks:
```

Summary of Code Size diffs:
(Lower is better)

Total bytes of base: 306240
Total bytes of diff: 306022
Total bytes of delta: -218 (-0.07% of base)
    diff is an improvement.
```
<details>

<summary>Detail diffs</summary>

```

Top file regressions (bytes):
         204 : 18210.dasm (13.98% of base)
         123 : 17149.dasm (3.84% of base)
         115 : 12617.dasm (1.95% of base)
         106 : 19256.dasm (5.92% of base)
         105 : 8717.dasm (8.19% of base)
          94 : 5445.dasm (9.49% of base)
          85 : 16452.dasm (1.48% of base)
          82 : 19234.dasm (12.01% of base)
          76 : 4626.dasm (20.05% of base)
          64 : 18620.dasm (6.97% of base)
          52 : 19202.dasm (16.20% of base)
          50 : 19210.dasm (3.15% of base)
          48 : 25971.dasm (0.66% of base)
          46 : 18490.dasm (6.05% of base)
          46 : 19131.dasm (8.44% of base)
          36 : 17812.dasm (1.84% of base)
          36 : 10409.dasm (4.20% of base)
          36 : 15922.dasm (17.48% of base)
          35 : 17997.dasm (11.18% of base)
          34 : 14621.dasm (4.82% of base)

Top file improvements (bytes):
        -557 : 18190.dasm (-19.94% of base)
        -525 : 18412.dasm (-12.80% of base)
        -260 : 18400.dasm (-19.89% of base)
        -202 : 17991.dasm (-16.67% of base)
        -201 : 20540.dasm (-18.91% of base)
        -200 : 18417.dasm (-9.96% of base)
        -159 : 17736.dasm (-7.87% of base)
        -128 : 18326.dasm (-7.15% of base)
         -90 : 18182.dasm (-4.71% of base)
         -67 : 18177.dasm (-3.94% of base)
         -59 : 18359.dasm (-5.13% of base)
         -53 : 20672.dasm (-8.02% of base)
         -53 : 18280.dasm (-10.77% of base)
         -45 : 18575.dasm (-8.08% of base)
         -42 : 16930.dasm (-7.89% of base)
         -40 : 17935.dasm (-4.77% of base)
         -38 : 17814.dasm (-2.11% of base)
         -38 : 18458.dasm (-4.87% of base)
         -36 : 18222.dasm (-3.07% of base)
         -36 : 18440.dasm (-6.75% of base)

376 total files with Code Size differences (153 improved, 223 regressed), 5 unchanged.

Top method regressions (bytes):
         204 (13.98% of base) : 18210.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol:MakeAcyclicInterfaces(Roslyn.Utilities.ConsList`1[[Microsoft.CodeAnalysis.CSharp.Symbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.DiagnosticBag):System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]:this
         123 ( 3.84% of base) : 17149.dasm - Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.LanguageParser:ParseNamespaceBody(byref,byref,byref,ushort):this
         115 ( 1.95% of base) : 12617.dasm - Utf8Json.Formatters.DictionaryFormatterBase`5[Int32,__Canon,__Canon,Enumerator,__Canon][System.Int32,System.__Canon,System.__Canon,System.Collections.Generic.Dictionary`2+Enumerator[System.Int32,System.__Canon],System.__Canon]:Serialize(byref,System.__Canon,Utf8Json.IJsonFormatterResolver):this
         106 ( 5.92% of base) : 19256.dasm - <Microsoft-Cci-ITypeDefinition-GetExplicitImplementationOverrides>d__31:MoveNext():bool:this
         105 ( 8.19% of base) : 8717.dasm - System.String:SplitWithPostProcessing(System.ReadOnlySpan`1[Int32],System.ReadOnlySpan`1[Int32],int,int,int):System.String[]:this
          94 ( 9.49% of base) : 5445.dasm - System.Uri:CreateUriInfo(long):this
          85 ( 1.48% of base) : 16452.dasm - DynamicClass:_DynamicMethod9(System.IO.TextReader,int):MicroBenchmarks.Serializers.MyEventsListerViewModel
          82 (12.01% of base) : 19234.dasm - <GetTopLevelTypesCore>d__53:MoveNext():bool:this
          76 (20.05% of base) : 4626.dasm - System.Collections.Generic.PriorityQueue`2[__Canon,__Canon][System.__Canon,System.__Canon]:MoveDownCustomComparer(System.ValueTuple`2[__Canon,__Canon],int):this
          64 ( 6.97% of base) : 18620.dasm - Microsoft.CodeAnalysis.CSharp.Binder:BindSimpleBinaryOperator(Microsoft.CodeAnalysis.CSharp.Syntax.BinaryExpressionSyntax,Microsoft.CodeAnalysis.DiagnosticBag):Microsoft.CodeAnalysis.CSharp.BoundExpression:this
          52 (16.20% of base) : 19202.dasm - <GetAssemblyReferencesFromAddedModules>d__36:MoveNext():bool:this
          50 ( 3.15% of base) : 19210.dasm - <GetTopLevelTypes>d__23[__Canon,__Canon,__Canon,__Canon,__Canon,__Canon,__Canon,__Canon,__Canon][System.__Canon,System.__Canon,System.__Canon,System.__Canon,System.__Canon,System.__Canon,System.__Canon,System.__Canon,System.__Canon]:MoveNext():bool:this
          48 ( 0.66% of base) : 25971.dasm - DynamicClass:_DynamicMethod1(System.IO.TextReader,int):MicroBenchmarks.Serializers.CollectionsOfPrimitives
          46 ( 6.05% of base) : 18490.dasm - Microsoft.CodeAnalysis.CSharp.ClsComplianceChecker:VisitAssembly(Microsoft.CodeAnalysis.CSharp.Symbols.AssemblySymbol):this
          46 ( 8.44% of base) : 19131.dasm - <AddedModulesResourceNames>d__200:MoveNext():bool:this
          36 ( 1.84% of base) : 17812.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamespaceSymbol:MakeNameToMembersMap(Microsoft.CodeAnalysis.DiagnosticBag):System.Collections.Generic.Dictionary`2[[System.String, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]], System.Collections.Immutable, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]]:this
          36 ( 4.20% of base) : 10409.dasm - System.Net.Security.SslStream:FillHandshakeBufferAsync(System.Net.Security.AsyncReadWriteAdapter,int):System.Threading.Tasks.ValueTask`1[Int32]:this
          36 (17.48% of base) : 15922.dasm - System.Number:DecimalToNumber(byref,byref)
          35 (11.18% of base) : 17997.dasm - <CreateNestedTypes>d__126:MoveNext():bool:this
          34 ( 4.82% of base) : 14621.dasm - BenchmarksGame.KNucleotide_1:Bench(System.IO.Stream,BenchmarksGame.NucleotideHelpers,bool):bool

Top method improvements (bytes):
        -557 (-19.94% of base) : 18190.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol:MakeDeclaredBases(Roslyn.Utilities.ConsList`1[[Microsoft.CodeAnalysis.CSharp.Symbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.DiagnosticBag):System.Tuple`2[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]], System.Collections.Immutable, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]]:this
        -525 (-12.80% of base) : 18412.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:ComputeInterfaceImplementations(Microsoft.CodeAnalysis.DiagnosticBag,System.Threading.CancellationToken):System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.SynthesizedExplicitImplementationForwardingMethod, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]:this
        -260 (-19.89% of base) : 18400.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.OverriddenOrHiddenMembersHelpers:FindOverriddenOrHiddenMembersInType(Microsoft.CodeAnalysis.CSharp.Symbol,bool,Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,byref,byref,byref)
        -202 (-16.67% of base) : 17991.dasm - Microsoft.CodeAnalysis.CSharp.CSharpCompilation:GetRuntimeMember(Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,byref,Microsoft.CodeAnalysis.RuntimeMembers.SignatureComparer`5[[Microsoft.CodeAnalysis.CSharp.Symbols.MethodSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.FieldSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.PropertySymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.ParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.CSharp.Symbols.AssemblySymbol):Microsoft.CodeAnalysis.CSharp.Symbol
        -201 (-18.91% of base) : 20540.dasm - Microsoft.CodeAnalysis.CSharp.SyntaxTreeSemanticModel:GetDeclaredMember(Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol,Microsoft.CodeAnalysis.Text.TextSpan,System.String):Microsoft.CodeAnalysis.CSharp.Symbol:this
        -200 (-9.96% of base) : 18417.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:CheckMemberNameConflicts(Microsoft.CodeAnalysis.DiagnosticBag):this
        -159 (-7.87% of base) : 17736.dasm - Microsoft.CodeAnalysis.CSharp.CSharpCompilation:GetDiagnostics(int,bool,Microsoft.CodeAnalysis.DiagnosticBag,System.Threading.CancellationToken):this
        -128 (-7.15% of base) : 18326.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:MakeTypeMembers(Microsoft.CodeAnalysis.DiagnosticBag):System.Collections.Generic.Dictionary`2[[System.String, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]], System.Collections.Immutable, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]]:this
         -90 (-4.71% of base) : 18182.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol:PostDecodeWellKnownAttributes(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.CSharpAttributeData, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Syntax.AttributeSyntax, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.DiagnosticBag,short,Microsoft.CodeAnalysis.WellKnownAttributeData):this
         -67 (-3.94% of base) : 18177.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:ForceComplete(Microsoft.CodeAnalysis.SourceLocation,System.Threading.CancellationToken):this
         -59 (-5.13% of base) : 18359.dasm - Microsoft.CodeAnalysis.CSharp.Binder:ValidateParameterNameConflicts(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.TypeParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.ParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.DiagnosticBag):this
         -53 (-8.02% of base) : 20672.dasm - Microsoft.CodeAnalysis.CSharp.Imports:LookupSymbolInUsings(System.Collections.Immutable.ImmutableArray`1[NamespaceOrTypeAndUsingDirective],Microsoft.CodeAnalysis.CSharp.Binder,Microsoft.CodeAnalysis.CSharp.LookupResult,System.String,int,Roslyn.Utilities.ConsList`1[[Microsoft.CodeAnalysis.CSharp.Symbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],int,bool,byref)
         -53 (-10.77% of base) : 18280.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol:GetSourceTypeMember(System.String,int,ushort,Microsoft.CodeAnalysis.CSharp.CSharpSyntaxNode):Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol:this
         -45 (-8.08% of base) : 18575.dasm - Microsoft.CodeAnalysis.CSharp.ExecutableCodeBinder:ValidateIteratorMethods(Microsoft.CodeAnalysis.DiagnosticBag):this
         -42 (-7.89% of base) : 16930.dasm - V8.Crypto.BigInteger:fromByteArray(System.Byte[]):this
         -40 (-4.77% of base) : 17935.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol:LookupMetadataType(byref):Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol:this
         -38 (-2.11% of base) : 17814.dasm - Microsoft.CodeAnalysis.CSharp.MergedNamespaceDeclaration:MakeChildren():System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.MergedNamespaceOrTypeDeclaration, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]:this
         -38 (-4.87% of base) : 18458.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberMethodSymbol:ForceComplete(Microsoft.CodeAnalysis.SourceLocation,System.Threading.CancellationToken):this
         -36 (-3.07% of base) : 18222.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:MakeAllMembers(Microsoft.CodeAnalysis.DiagnosticBag):System.Collections.Generic.Dictionary`2[[System.String, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]], System.Collections.Immutable, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]]:this
         -36 (-6.75% of base) : 18440.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:CheckTypeParameterNameConflicts(Microsoft.CodeAnalysis.DiagnosticBag):this

Top method regressions (percentages):
          17 (36.17% of base) : 22943.dasm - System.Collections.IndexerSetReverse`1[Int32][System.Int32]:Array():System.Int32[]:this
          17 (36.17% of base) : 24496.dasm - System.Collections.IndexerSetReverse`1[__Canon][System.__Canon]:Array():System.__Canon[]:this
          18 (27.27% of base) : 13842.dasm - System.Collections.IterateFor`1[__Canon][System.__Canon]:Get(System.Collections.Generic.IList`1[__Canon]):System.__Canon:this
          15 (26.79% of base) : 13055.dasm - System.Number:UInt32ToDecChars(long,int,int):long
          15 (25.86% of base) : 975.dasm - System.Number:UInt32ToDecChars(long,int,int):long
          16 (25.81% of base) : 20092.dasm - System.Collections.IndexerSet`1[__Canon][System.__Canon]:Set(System.Collections.Generic.IList`1[__Canon]):System.Collections.Generic.IList`1[__Canon]:this
          22 (25.58% of base) : 9613.dasm - System.Xml.XmlLoader:LoadDocSequence(System.Xml.XmlDocument):this
          18 (25.35% of base) : 11926.dasm - EMFloatClass:normalize(InternalFPF)
          14 (22.95% of base) : 25097.dasm - V8.Richards.Packet:addTo(V8.Richards.Packet):V8.Richards.Packet:this
          16 (21.92% of base) : 4954.dasm - System.IO.Compression.DeflateStream:WriteDeflaterOutput():this
          10 (20.41% of base) : 27331.dasm - System.Collections.IterateFor`1[Int32][System.Int32]:ImmutableList():int:this
          10 (20.41% of base) : 9944.dasm - System.Collections.IterateFor`1[Int32][System.Int32]:ImmutableSortedSet():int:this
          76 (20.05% of base) : 4626.dasm - System.Collections.Generic.PriorityQueue`2[__Canon,__Canon][System.__Canon,System.__Canon]:MoveDownCustomComparer(System.ValueTuple`2[__Canon,__Canon],int):this
          10 (20.00% of base) : 14834.dasm - System.Collections.IterateFor`1[__Canon][System.__Canon]:ImmutableList():System.__Canon:this
          10 (20.00% of base) : 15485.dasm - System.Collections.IterateFor`1[__Canon][System.__Canon]:ImmutableSortedSet():System.__Canon:this
          24 (19.05% of base) : 8484.dasm - System.Collections.IterateForEach`1[__Canon][System.__Canon]:ImmutableArray():System.__Canon:this
          17 (18.09% of base) : 11992.dasm - Newtonsoft.Json.Utilities.DateTimeUtils:CopyIntToCharArray(System.Char[],int,int,int)
           9 (18.00% of base) : 19831.dasm - System.Reflection.Metadata.Ecma335.MetadataSizes:CalculateTableStreamHeaderSize():int:this
          16 (17.98% of base) : 4541.dasm - System.Collections.IndexerSetReverse`1[__Canon][System.__Canon]:Span():System.__Canon:this
          36 (17.48% of base) : 15922.dasm - System.Number:DecimalToNumber(byref,byref)

Top method improvements (percentages):
         -19 (-28.79% of base) : 18465.dasm - Microsoft.CodeAnalysis.CSharp.MergedTypeDeclaration:get_AnyMemberHasAttributes():bool:this
        -557 (-19.94% of base) : 18190.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol:MakeDeclaredBases(Roslyn.Utilities.ConsList`1[[Microsoft.CodeAnalysis.CSharp.Symbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.DiagnosticBag):System.Tuple`2[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]], System.Collections.Immutable, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]]:this
        -260 (-19.89% of base) : 18400.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.OverriddenOrHiddenMembersHelpers:FindOverriddenOrHiddenMembersInType(Microsoft.CodeAnalysis.CSharp.Symbol,bool,Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,byref,byref,byref)
         -30 (-19.35% of base) : 19588.dasm - Microsoft.Cci.MetadataWriter:MayUseSmallExceptionHeaders(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.ExceptionHandlerRegion, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):bool
        -201 (-18.91% of base) : 20540.dasm - Microsoft.CodeAnalysis.CSharp.SyntaxTreeSemanticModel:GetDeclaredMember(Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol,Microsoft.CodeAnalysis.Text.TextSpan,System.String):Microsoft.CodeAnalysis.CSharp.Symbol:this
         -11 (-16.92% of base) : 18912.dasm - Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator:EmitStatements(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.BoundStatement, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-16.92% of base) : 18800.dasm - Microsoft.CodeAnalysis.CSharp.DataFlowPass:DeclareVariables(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.LocalSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-16.92% of base) : 18812.dasm - Microsoft.CodeAnalysis.CSharp.DataFlowPass:ReportUnusedVariables(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.LocalFunctionSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
        -202 (-16.67% of base) : 17991.dasm - Microsoft.CodeAnalysis.CSharp.CSharpCompilation:GetRuntimeMember(Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,byref,Microsoft.CodeAnalysis.RuntimeMembers.SignatureComparer`5[[Microsoft.CodeAnalysis.CSharp.Symbols.MethodSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.FieldSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.PropertySymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.ParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.CSharp.Symbols.AssemblySymbol):Microsoft.CodeAnalysis.CSharp.Symbol
         -11 (-16.18% of base) : 20764.dasm - Microsoft.CodeAnalysis.CSharp.AbstractRegionDataFlowPass:MakeSlots(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.ParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.94% of base) : 19532.dasm - Microsoft.Cci.MetadataVisitor:Visit(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.IParameterDefinition, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.71% of base) : 19548.dasm - Microsoft.Cci.MetadataVisitor:Visit(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.ILocalDefinition, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.71% of base) : 19553.dasm - Microsoft.Cci.MetadataVisitor:Visit(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.ExceptionHandlerRegion, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.71% of base) : 19457.dasm - Microsoft.Cci.MetadataVisitor:Visit(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.IParameterTypeInformation, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.71% of base) : 19459.dasm - Microsoft.Cci.MetadataVisitor:Visit(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.ICustomModifier, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.49% of base) : 18811.dasm - Microsoft.CodeAnalysis.CSharp.DataFlowPass:ReportUnusedVariables(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.LocalSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.07% of base) : 18797.dasm - Microsoft.CodeAnalysis.CSharp.DataFlowPass:EnterParameters(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.ParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.07% of base) : 20750.dasm - Microsoft.CodeAnalysis.CSharp.PreciseAbstractFlowPass`1[LocalState][Microsoft.CodeAnalysis.CSharp.DataFlowPass+LocalState]:VisitMultipleLocalDeclarations(Microsoft.CodeAnalysis.CSharp.BoundMultipleLocalDeclarations):Microsoft.CodeAnalysis.CSharp.BoundNode:this
         -11 (-15.07% of base) : 18768.dasm - Microsoft.CodeAnalysis.CSharp.PreciseAbstractFlowPass`1[LocalState][Microsoft.CodeAnalysis.CSharp.ControlFlowPass+LocalState]:VisitStatements(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.BoundStatement, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -12 (-13.64% of base) : 18415.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:CheckMemberNamesDistinctFromType(Microsoft.CodeAnalysis.DiagnosticBag):this

376 total methods with Code Size differences (153 improved, 223 regressed), 5 unchanged.

```

</details>

--------------------------------------------------------------------------------

Additionally, I removed some dead "optimization enabling" code.
BruceForstall added a commit that referenced this issue Apr 13, 2021
@BruceForstall
Generalize loop inversion (#50982)
4b6ac1b 
* Generalize loop inversion

Starting with an experimental branch from @AndyAyersMS,
generalize the loop inversion `optInvertWhileLoop` code
to consider duplicating an entire conditional block, not
just a conditional block that contains exactly one JTRUE
tree. Since the JTRUE itself wasn't considered before in
the costing, bump up the maximum cost allowed by 2 to account
for that. (Note that there is a lot of room here for tuning
the cost/benefit analysis.)

Additionally, the code already bumped the allowed cost if the
condition tree contained calls to a shared static helper. Add
another boost if the tree contains array.Length expressions,
which are likely to be CSE'ed.

Loop inversion by itself doesn't buy much, but our downstream
phases, like natural loop recognition, loop hoisting, and loop
cloning, depend on an inverted loop structure with a zero trip
test.

There are many diffs, typically size regressions because we
are duplicating code. Some notable cases:
1. BenchI Puzzle. This was a motivating example, from #6569.
It ends up with multiple new CSEs and BDN shows a 24% run-time
improvement.
2. RegexRedux_5 and ReverseComplement_1 also report faster
3. On the contrary, FannkuchRedux_5 reports 23% slower. It appears
we create fewer CSEs and end up with a couple more instructions
inside some tight loops.
4. Other things typically seen in diffs: (a) removed null and
bounds checks, (b) additional CSEs, (c) loop alignment kicks in.

The loop matching at the stage inversion runs is lexical and very
simplistic, as it is before natural loop recognition. As a result,
for some loops, like multiple-condition `while` loops (e.g.,
`while (--digits >= 0 || value != 0)` in
`System.Number:UInt32ToDecChars`), the inversion ends up creating
some pretty weird flow. (That's actually not new to this change.)

I added a `COMPlus_JitDoLoopInversion` config to allow turning
off the phase to do experiments.

Here are the diffs for SPMI on the benchmarks:
```

Summary of Code Size diffs:
(Lower is better)

Total bytes of base: 306240
Total bytes of diff: 306022
Total bytes of delta: -218 (-0.07% of base)
    diff is an improvement.
```
<details>

<summary>Detail diffs</summary>

```

Top file regressions (bytes):
         204 : 18210.dasm (13.98% of base)
         123 : 17149.dasm (3.84% of base)
         115 : 12617.dasm (1.95% of base)
         106 : 19256.dasm (5.92% of base)
         105 : 8717.dasm (8.19% of base)
          94 : 5445.dasm (9.49% of base)
          85 : 16452.dasm (1.48% of base)
          82 : 19234.dasm (12.01% of base)
          76 : 4626.dasm (20.05% of base)
          64 : 18620.dasm (6.97% of base)
          52 : 19202.dasm (16.20% of base)
          50 : 19210.dasm (3.15% of base)
          48 : 25971.dasm (0.66% of base)
          46 : 18490.dasm (6.05% of base)
          46 : 19131.dasm (8.44% of base)
          36 : 17812.dasm (1.84% of base)
          36 : 10409.dasm (4.20% of base)
          36 : 15922.dasm (17.48% of base)
          35 : 17997.dasm (11.18% of base)
          34 : 14621.dasm (4.82% of base)

Top file improvements (bytes):
        -557 : 18190.dasm (-19.94% of base)
        -525 : 18412.dasm (-12.80% of base)
        -260 : 18400.dasm (-19.89% of base)
        -202 : 17991.dasm (-16.67% of base)
        -201 : 20540.dasm (-18.91% of base)
        -200 : 18417.dasm (-9.96% of base)
        -159 : 17736.dasm (-7.87% of base)
        -128 : 18326.dasm (-7.15% of base)
         -90 : 18182.dasm (-4.71% of base)
         -67 : 18177.dasm (-3.94% of base)
         -59 : 18359.dasm (-5.13% of base)
         -53 : 20672.dasm (-8.02% of base)
         -53 : 18280.dasm (-10.77% of base)
         -45 : 18575.dasm (-8.08% of base)
         -42 : 16930.dasm (-7.89% of base)
         -40 : 17935.dasm (-4.77% of base)
         -38 : 17814.dasm (-2.11% of base)
         -38 : 18458.dasm (-4.87% of base)
         -36 : 18222.dasm (-3.07% of base)
         -36 : 18440.dasm (-6.75% of base)

376 total files with Code Size differences (153 improved, 223 regressed), 5 unchanged.

Top method regressions (bytes):
         204 (13.98% of base) : 18210.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol:MakeAcyclicInterfaces(Roslyn.Utilities.ConsList`1[[Microsoft.CodeAnalysis.CSharp.Symbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.DiagnosticBag):System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]:this
         123 ( 3.84% of base) : 17149.dasm - Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.LanguageParser:ParseNamespaceBody(byref,byref,byref,ushort):this
         115 ( 1.95% of base) : 12617.dasm - Utf8Json.Formatters.DictionaryFormatterBase`5[Int32,__Canon,__Canon,Enumerator,__Canon][System.Int32,System.__Canon,System.__Canon,System.Collections.Generic.Dictionary`2+Enumerator[System.Int32,System.__Canon],System.__Canon]:Serialize(byref,System.__Canon,Utf8Json.IJsonFormatterResolver):this
         106 ( 5.92% of base) : 19256.dasm - <Microsoft-Cci-ITypeDefinition-GetExplicitImplementationOverrides>d__31:MoveNext():bool:this
         105 ( 8.19% of base) : 8717.dasm - System.String:SplitWithPostProcessing(System.ReadOnlySpan`1[Int32],System.ReadOnlySpan`1[Int32],int,int,int):System.String[]:this
          94 ( 9.49% of base) : 5445.dasm - System.Uri:CreateUriInfo(long):this
          85 ( 1.48% of base) : 16452.dasm - DynamicClass:_DynamicMethod9(System.IO.TextReader,int):MicroBenchmarks.Serializers.MyEventsListerViewModel
          82 (12.01% of base) : 19234.dasm - <GetTopLevelTypesCore>d__53:MoveNext():bool:this
          76 (20.05% of base) : 4626.dasm - System.Collections.Generic.PriorityQueue`2[__Canon,__Canon][System.__Canon,System.__Canon]:MoveDownCustomComparer(System.ValueTuple`2[__Canon,__Canon],int):this
          64 ( 6.97% of base) : 18620.dasm - Microsoft.CodeAnalysis.CSharp.Binder:BindSimpleBinaryOperator(Microsoft.CodeAnalysis.CSharp.Syntax.BinaryExpressionSyntax,Microsoft.CodeAnalysis.DiagnosticBag):Microsoft.CodeAnalysis.CSharp.BoundExpression:this
          52 (16.20% of base) : 19202.dasm - <GetAssemblyReferencesFromAddedModules>d__36:MoveNext():bool:this
          50 ( 3.15% of base) : 19210.dasm - <GetTopLevelTypes>d__23[__Canon,__Canon,__Canon,__Canon,__Canon,__Canon,__Canon,__Canon,__Canon][System.__Canon,System.__Canon,System.__Canon,System.__Canon,System.__Canon,System.__Canon,System.__Canon,System.__Canon,System.__Canon]:MoveNext():bool:this
          48 ( 0.66% of base) : 25971.dasm - DynamicClass:_DynamicMethod1(System.IO.TextReader,int):MicroBenchmarks.Serializers.CollectionsOfPrimitives
          46 ( 6.05% of base) : 18490.dasm - Microsoft.CodeAnalysis.CSharp.ClsComplianceChecker:VisitAssembly(Microsoft.CodeAnalysis.CSharp.Symbols.AssemblySymbol):this
          46 ( 8.44% of base) : 19131.dasm - <AddedModulesResourceNames>d__200:MoveNext():bool:this
          36 ( 1.84% of base) : 17812.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamespaceSymbol:MakeNameToMembersMap(Microsoft.CodeAnalysis.DiagnosticBag):System.Collections.Generic.Dictionary`2[[System.String, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]], System.Collections.Immutable, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]]:this
          36 ( 4.20% of base) : 10409.dasm - System.Net.Security.SslStream:FillHandshakeBufferAsync(System.Net.Security.AsyncReadWriteAdapter,int):System.Threading.Tasks.ValueTask`1[Int32]:this
          36 (17.48% of base) : 15922.dasm - System.Number:DecimalToNumber(byref,byref)
          35 (11.18% of base) : 17997.dasm - <CreateNestedTypes>d__126:MoveNext():bool:this
          34 ( 4.82% of base) : 14621.dasm - BenchmarksGame.KNucleotide_1:Bench(System.IO.Stream,BenchmarksGame.NucleotideHelpers,bool):bool

Top method improvements (bytes):
        -557 (-19.94% of base) : 18190.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol:MakeDeclaredBases(Roslyn.Utilities.ConsList`1[[Microsoft.CodeAnalysis.CSharp.Symbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.DiagnosticBag):System.Tuple`2[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]], System.Collections.Immutable, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]]:this
        -525 (-12.80% of base) : 18412.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:ComputeInterfaceImplementations(Microsoft.CodeAnalysis.DiagnosticBag,System.Threading.CancellationToken):System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.SynthesizedExplicitImplementationForwardingMethod, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]:this
        -260 (-19.89% of base) : 18400.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.OverriddenOrHiddenMembersHelpers:FindOverriddenOrHiddenMembersInType(Microsoft.CodeAnalysis.CSharp.Symbol,bool,Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,byref,byref,byref)
        -202 (-16.67% of base) : 17991.dasm - Microsoft.CodeAnalysis.CSharp.CSharpCompilation:GetRuntimeMember(Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,byref,Microsoft.CodeAnalysis.RuntimeMembers.SignatureComparer`5[[Microsoft.CodeAnalysis.CSharp.Symbols.MethodSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.FieldSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.PropertySymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.ParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.CSharp.Symbols.AssemblySymbol):Microsoft.CodeAnalysis.CSharp.Symbol
        -201 (-18.91% of base) : 20540.dasm - Microsoft.CodeAnalysis.CSharp.SyntaxTreeSemanticModel:GetDeclaredMember(Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol,Microsoft.CodeAnalysis.Text.TextSpan,System.String):Microsoft.CodeAnalysis.CSharp.Symbol:this
        -200 (-9.96% of base) : 18417.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:CheckMemberNameConflicts(Microsoft.CodeAnalysis.DiagnosticBag):this
        -159 (-7.87% of base) : 17736.dasm - Microsoft.CodeAnalysis.CSharp.CSharpCompilation:GetDiagnostics(int,bool,Microsoft.CodeAnalysis.DiagnosticBag,System.Threading.CancellationToken):this
        -128 (-7.15% of base) : 18326.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:MakeTypeMembers(Microsoft.CodeAnalysis.DiagnosticBag):System.Collections.Generic.Dictionary`2[[System.String, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]], System.Collections.Immutable, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]]:this
         -90 (-4.71% of base) : 18182.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol:PostDecodeWellKnownAttributes(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.CSharpAttributeData, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Syntax.AttributeSyntax, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.DiagnosticBag,short,Microsoft.CodeAnalysis.WellKnownAttributeData):this
         -67 (-3.94% of base) : 18177.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:ForceComplete(Microsoft.CodeAnalysis.SourceLocation,System.Threading.CancellationToken):this
         -59 (-5.13% of base) : 18359.dasm - Microsoft.CodeAnalysis.CSharp.Binder:ValidateParameterNameConflicts(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.TypeParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.ParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.DiagnosticBag):this
         -53 (-8.02% of base) : 20672.dasm - Microsoft.CodeAnalysis.CSharp.Imports:LookupSymbolInUsings(System.Collections.Immutable.ImmutableArray`1[NamespaceOrTypeAndUsingDirective],Microsoft.CodeAnalysis.CSharp.Binder,Microsoft.CodeAnalysis.CSharp.LookupResult,System.String,int,Roslyn.Utilities.ConsList`1[[Microsoft.CodeAnalysis.CSharp.Symbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],int,bool,byref)
         -53 (-10.77% of base) : 18280.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol:GetSourceTypeMember(System.String,int,ushort,Microsoft.CodeAnalysis.CSharp.CSharpSyntaxNode):Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol:this
         -45 (-8.08% of base) : 18575.dasm - Microsoft.CodeAnalysis.CSharp.ExecutableCodeBinder:ValidateIteratorMethods(Microsoft.CodeAnalysis.DiagnosticBag):this
         -42 (-7.89% of base) : 16930.dasm - V8.Crypto.BigInteger:fromByteArray(System.Byte[]):this
         -40 (-4.77% of base) : 17935.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol:LookupMetadataType(byref):Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol:this
         -38 (-2.11% of base) : 17814.dasm - Microsoft.CodeAnalysis.CSharp.MergedNamespaceDeclaration:MakeChildren():System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.MergedNamespaceOrTypeDeclaration, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]:this
         -38 (-4.87% of base) : 18458.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberMethodSymbol:ForceComplete(Microsoft.CodeAnalysis.SourceLocation,System.Threading.CancellationToken):this
         -36 (-3.07% of base) : 18222.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:MakeAllMembers(Microsoft.CodeAnalysis.DiagnosticBag):System.Collections.Generic.Dictionary`2[[System.String, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]], System.Collections.Immutable, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]]:this
         -36 (-6.75% of base) : 18440.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:CheckTypeParameterNameConflicts(Microsoft.CodeAnalysis.DiagnosticBag):this

Top method regressions (percentages):
          17 (36.17% of base) : 22943.dasm - System.Collections.IndexerSetReverse`1[Int32][System.Int32]:Array():System.Int32[]:this
          17 (36.17% of base) : 24496.dasm - System.Collections.IndexerSetReverse`1[__Canon][System.__Canon]:Array():System.__Canon[]:this
          18 (27.27% of base) : 13842.dasm - System.Collections.IterateFor`1[__Canon][System.__Canon]:Get(System.Collections.Generic.IList`1[__Canon]):System.__Canon:this
          15 (26.79% of base) : 13055.dasm - System.Number:UInt32ToDecChars(long,int,int):long
          15 (25.86% of base) : 975.dasm - System.Number:UInt32ToDecChars(long,int,int):long
          16 (25.81% of base) : 20092.dasm - System.Collections.IndexerSet`1[__Canon][System.__Canon]:Set(System.Collections.Generic.IList`1[__Canon]):System.Collections.Generic.IList`1[__Canon]:this
          22 (25.58% of base) : 9613.dasm - System.Xml.XmlLoader:LoadDocSequence(System.Xml.XmlDocument):this
          18 (25.35% of base) : 11926.dasm - EMFloatClass:normalize(InternalFPF)
          14 (22.95% of base) : 25097.dasm - V8.Richards.Packet:addTo(V8.Richards.Packet):V8.Richards.Packet:this
          16 (21.92% of base) : 4954.dasm - System.IO.Compression.DeflateStream:WriteDeflaterOutput():this
          10 (20.41% of base) : 27331.dasm - System.Collections.IterateFor`1[Int32][System.Int32]:ImmutableList():int:this
          10 (20.41% of base) : 9944.dasm - System.Collections.IterateFor`1[Int32][System.Int32]:ImmutableSortedSet():int:this
          76 (20.05% of base) : 4626.dasm - System.Collections.Generic.PriorityQueue`2[__Canon,__Canon][System.__Canon,System.__Canon]:MoveDownCustomComparer(System.ValueTuple`2[__Canon,__Canon],int):this
          10 (20.00% of base) : 14834.dasm - System.Collections.IterateFor`1[__Canon][System.__Canon]:ImmutableList():System.__Canon:this
          10 (20.00% of base) : 15485.dasm - System.Collections.IterateFor`1[__Canon][System.__Canon]:ImmutableSortedSet():System.__Canon:this
          24 (19.05% of base) : 8484.dasm - System.Collections.IterateForEach`1[__Canon][System.__Canon]:ImmutableArray():System.__Canon:this
          17 (18.09% of base) : 11992.dasm - Newtonsoft.Json.Utilities.DateTimeUtils:CopyIntToCharArray(System.Char[],int,int,int)
           9 (18.00% of base) : 19831.dasm - System.Reflection.Metadata.Ecma335.MetadataSizes:CalculateTableStreamHeaderSize():int:this
          16 (17.98% of base) : 4541.dasm - System.Collections.IndexerSetReverse`1[__Canon][System.__Canon]:Span():System.__Canon:this
          36 (17.48% of base) : 15922.dasm - System.Number:DecimalToNumber(byref,byref)

Top method improvements (percentages):
         -19 (-28.79% of base) : 18465.dasm - Microsoft.CodeAnalysis.CSharp.MergedTypeDeclaration:get_AnyMemberHasAttributes():bool:this
        -557 (-19.94% of base) : 18190.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceNamedTypeSymbol:MakeDeclaredBases(Roslyn.Utilities.ConsList`1[[Microsoft.CodeAnalysis.CSharp.Symbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.DiagnosticBag):System.Tuple`2[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]], System.Collections.Immutable, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]]:this
        -260 (-19.89% of base) : 18400.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.OverriddenOrHiddenMembersHelpers:FindOverriddenOrHiddenMembersInType(Microsoft.CodeAnalysis.CSharp.Symbol,bool,Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,byref,byref,byref)
         -30 (-19.35% of base) : 19588.dasm - Microsoft.Cci.MetadataWriter:MayUseSmallExceptionHeaders(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.ExceptionHandlerRegion, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):bool
        -201 (-18.91% of base) : 20540.dasm - Microsoft.CodeAnalysis.CSharp.SyntaxTreeSemanticModel:GetDeclaredMember(Microsoft.CodeAnalysis.CSharp.Symbols.NamespaceOrTypeSymbol,Microsoft.CodeAnalysis.Text.TextSpan,System.String):Microsoft.CodeAnalysis.CSharp.Symbol:this
         -11 (-16.92% of base) : 18912.dasm - Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator:EmitStatements(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.BoundStatement, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-16.92% of base) : 18800.dasm - Microsoft.CodeAnalysis.CSharp.DataFlowPass:DeclareVariables(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.LocalSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-16.92% of base) : 18812.dasm - Microsoft.CodeAnalysis.CSharp.DataFlowPass:ReportUnusedVariables(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.LocalFunctionSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
        -202 (-16.67% of base) : 17991.dasm - Microsoft.CodeAnalysis.CSharp.CSharpCompilation:GetRuntimeMember(Microsoft.CodeAnalysis.CSharp.Symbols.NamedTypeSymbol,byref,Microsoft.CodeAnalysis.RuntimeMembers.SignatureComparer`5[[Microsoft.CodeAnalysis.CSharp.Symbols.MethodSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.FieldSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.PropertySymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.TypeSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35],[Microsoft.CodeAnalysis.CSharp.Symbols.ParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]],Microsoft.CodeAnalysis.CSharp.Symbols.AssemblySymbol):Microsoft.CodeAnalysis.CSharp.Symbol
         -11 (-16.18% of base) : 20764.dasm - Microsoft.CodeAnalysis.CSharp.AbstractRegionDataFlowPass:MakeSlots(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.ParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.94% of base) : 19532.dasm - Microsoft.Cci.MetadataVisitor:Visit(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.IParameterDefinition, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.71% of base) : 19548.dasm - Microsoft.Cci.MetadataVisitor:Visit(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.ILocalDefinition, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.71% of base) : 19553.dasm - Microsoft.Cci.MetadataVisitor:Visit(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.ExceptionHandlerRegion, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.71% of base) : 19457.dasm - Microsoft.Cci.MetadataVisitor:Visit(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.IParameterTypeInformation, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.71% of base) : 19459.dasm - Microsoft.Cci.MetadataVisitor:Visit(System.Collections.Immutable.ImmutableArray`1[[Microsoft.Cci.ICustomModifier, Microsoft.CodeAnalysis, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.49% of base) : 18811.dasm - Microsoft.CodeAnalysis.CSharp.DataFlowPass:ReportUnusedVariables(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.LocalSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.07% of base) : 18797.dasm - Microsoft.CodeAnalysis.CSharp.DataFlowPass:EnterParameters(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.Symbols.ParameterSymbol, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -11 (-15.07% of base) : 20750.dasm - Microsoft.CodeAnalysis.CSharp.PreciseAbstractFlowPass`1[LocalState][Microsoft.CodeAnalysis.CSharp.DataFlowPass+LocalState]:VisitMultipleLocalDeclarations(Microsoft.CodeAnalysis.CSharp.BoundMultipleLocalDeclarations):Microsoft.CodeAnalysis.CSharp.BoundNode:this
         -11 (-15.07% of base) : 18768.dasm - Microsoft.CodeAnalysis.CSharp.PreciseAbstractFlowPass`1[LocalState][Microsoft.CodeAnalysis.CSharp.ControlFlowPass+LocalState]:VisitStatements(System.Collections.Immutable.ImmutableArray`1[[Microsoft.CodeAnalysis.CSharp.BoundStatement, Microsoft.CodeAnalysis.CSharp, Version=2.10.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]):this
         -12 (-13.64% of base) : 18415.dasm - Microsoft.CodeAnalysis.CSharp.Symbols.SourceMemberContainerTypeSymbol:CheckMemberNamesDistinctFromType(Microsoft.CodeAnalysis.DiagnosticBag):this

376 total methods with Code Size differences (153 improved, 223 regressed), 5 unchanged.

```

</details>

--------------------------------------------------------------------------------

Additionally, I removed some dead "optimization enabling" code.

* Code review feedback: fix one condition
@BruceForstall
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This was fixed by #50982

@ghost ghost locked as resolved and limited conversation to collaborators May 24, 2021
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area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI enhancement Product code improvement that does NOT require public API changes/additions optimization tenet-performance Performance related issue
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@msftgits @AndyAyersMS @JosephTremoulet @BruceForstall @JulieLeeMSFT