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 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.

src/coreclr/jit/compiler.h

@@ -6545,6 +6545,15 @@ class Compiler
         }
     }
 
+    // Struct used in optInvertWhileLoop to count interesting constructs to boost the profitability score.
+    struct OptInvertCountTreeInfoType
+    {
+        int sharedStaticHelperCount;
+        int arrayLengthCount;
+    };
+
+    static fgWalkResult optInvertCountTreeInfo(GenTree** pTree, fgWalkData* data);
+
     void optInvertWhileLoop(BasicBlock* block);
 
     bool optComputeLoopRep(int        constInit,
@@ -6573,9 +6582,6 @@ class Compiler
      *                       Optimization conditions
      *************************************************************************/
 
-    bool optFastCodeOrBlendedLoop(BasicBlock::weight_t bbWeight);
-    bool optPentium4(void);
-    bool optAvoidIncDec(BasicBlock::weight_t bbWeight);
     bool optAvoidIntMult(void);
 
 protected:

src/coreclr/jit/compiler.hpp

@@ -3614,27 +3614,6 @@ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 */
 
-// are we compiling for fast code, or are we compiling for blended code and
-// inside a loop?
-// We return true for BLENDED_CODE if the Block executes more than BB_LOOP_WEIGHT_SCALE/2
-inline bool Compiler::optFastCodeOrBlendedLoop(BasicBlock::weight_t bbWeight)
-{
-    return (compCodeOpt() == FAST_CODE) ||
-           ((compCodeOpt() == BLENDED_CODE) && (bbWeight > ((BB_LOOP_WEIGHT_SCALE / 2) * BB_UNITY_WEIGHT)));
-}
-
-// are we running on a Intel Pentium 4?
-inline bool Compiler::optPentium4(void)
-{
-    return (info.genCPU == CPU_X86_PENTIUM_4);
-}
-
-// should we use add/sub instead of inc/dec? (faster on P4, but increases size)
-inline bool Compiler::optAvoidIncDec(BasicBlock::weight_t bbWeight)
-{
-    return optPentium4() && optFastCodeOrBlendedLoop(bbWeight);
-}
-
 // should we try to replace integer multiplication with lea/add/shift sequences?
 inline bool Compiler::optAvoidIntMult(void)
 {

src/coreclr/jit/jitconfigvalues.h

@@ -372,6 +372,7 @@ CONFIG_INTEGER(JitDoAssertionProp, W("JitDoAssertionProp"), 1) // Perform assert
 CONFIG_INTEGER(JitDoCopyProp, W("JitDoCopyProp"), 1)   // Perform copy propagation on variables that appear redundant
 CONFIG_INTEGER(JitDoEarlyProp, W("JitDoEarlyProp"), 1) // Perform Early Value Propagation
 CONFIG_INTEGER(JitDoLoopHoisting, W("JitDoLoopHoisting"), 1)   // Perform loop hoisting on loop invariant values
+CONFIG_INTEGER(JitDoLoopInversion, W("JitDoLoopInversion"), 1) // Perform loop inversion on "for/while" loops
 CONFIG_INTEGER(JitDoRangeAnalysis, W("JitDoRangeAnalysis"), 1) // Perform range check analysis
 CONFIG_INTEGER(JitDoRedundantBranchOpts, W("JitDoRedundantBranchOpts"), 1) // Perform redundant branch optimizations
 CONFIG_INTEGER(JitDoSsa, W("JitDoSsa"), 1) // Perform Static Single Assignment (SSA) numbering on the variables