Changes for basic block flags.

[erozenfeld]

1. Fix the code that propagates flags from the basic block of the return
   expression to the caller's basic block during inlining. We are now
   properly tracking the basic block of the return expression.
   Fixes Assertion failed 'false' during 'Early Value Propagation' #36588.

2. Don't mark BBJ_RETURN blocks with BBF_BACKWARD_JUMP since they are
   executed at most once.

The first change had a few diffs because we propagated BBF_BACKWARD_JUMP
flag. After analyzing them I realized that we shouldn't mark BBJ_RETURN
blocks with BBF_BACKWARD_JUMP in the first place. That resulted in some
diffs because we are less aggressive with inlining of calls outside of
loops.

[erozenfeld]

x64 framework diffs:

PMI CodeSize Diffs for System.Private.CoreLib.dll, framework assemblies for  default jit
Summary of Code Size diffs:
(Lower is better)
Total bytes of diff: -9167 (-0.02% of base)
    diff is an improvement.
Top file regressions (bytes):
          26 : System.Private.CoreLib.dasm (0.00% of base)
           1 : System.Text.Encoding.CodePages.dasm (0.00% of base)
Top file improvements (bytes):
       -2712 : Microsoft.CodeAnalysis.CSharp.dasm (-0.06% of base)
       -1957 : Microsoft.CodeAnalysis.VisualBasic.dasm (-0.03% of base)
       -1163 : System.Private.Xml.dasm (-0.03% of base)
        -952 : System.Threading.Channels.dasm (-0.53% of base)
        -902 : Microsoft.CodeAnalysis.dasm (-0.05% of base)
        -351 : System.Reflection.Metadata.dasm (-0.08% of base)
        -193 : Newtonsoft.Json.dasm (-0.02% of base)
        -177 : System.Reflection.MetadataLoadContext.dasm (-0.10% of base)
        -131 : xunit.runner.utility.netcoreapp10.dasm (-0.07% of base)
        -130 : System.Text.Json.dasm (-0.02% of base)
        -116 : ILCompiler.Reflection.ReadyToRun.dasm (-0.09% of base)
        -101 : System.Collections.Immutable.dasm (-0.01% of base)
         -63 : System.Security.Cryptography.Cng.dasm (-0.03% of base)
         -59 : System.Drawing.Common.dasm (-0.02% of base)
         -54 : System.Linq.Expressions.dasm (-0.01% of base)
         -53 : System.DirectoryServices.AccountManagement.dasm (-0.01% of base)
         -37 : Microsoft.Diagnostics.Tracing.TraceEvent.dasm (-0.00% of base)
         -24 : System.Data.Common.dasm (-0.00% of base)
         -12 : Microsoft.Extensions.Caching.Memory.dasm (-0.08% of base)
          -5 : Microsoft.CSharp.dasm (-0.00% of base)
23 total files with Code Size differences (21 improved, 2 regressed), 240 unchanged.
Top method regressions (bytes):
          79 ( 6.76% of base) : System.Private.CoreLib.dasm - ManifestBuilder:TranslateToManifestConvention(String,String):String:this
          21 ( 3.39% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Parser:ParseXmlMarkupDecl(SyntaxListBuilder`1):this
          13 ( 1.52% of base) : Newtonsoft.Json.dasm - JPath:TryParseValue(byref):bool:this
           9 ( 1.53% of base) : System.Private.Xml.dasm - TailCallAnalyzer:AnalyzeDefinition(QilNode)
           5 ( 0.52% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Parser:ParseNamedArguments(SeparatedSyntaxListBuilder`1):this
           1 ( 0.04% of base) : System.Text.Encoding.CodePages.dasm - GB18030Encoding:GetChars(long,int,long,int,DecoderNLS):int:this
Top method improvements (bytes):
        -728 (-8.36% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - SourceMemberContainerTypeSymbol:GenerateVarianceDiagnosticsForTypeRecursively(TypeSymbol,short,int,VarianceDiagnosticsTargetTypeParameter,int,byref):this
        -358 (-40.09% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Binder:CheckParameterNameNotDuplicate(ArrayBuilder`1,int,ParameterSyntax,ParameterSymbol,DiagnosticBag):this
        -344 (-19.95% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Binder:ReportMutableStructureConstraintsInUsing(TypeSymbol,String,VisualBasicSyntaxNode,DiagnosticBag):this
        -282 (-46.53% of base) : Microsoft.CodeAnalysis.CSharp.dasm - Binder:BindQueryInternal2(QueryTranslationState,DiagnosticBag):BoundExpression:this
        -243 (-20.82% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - DocumentationCommentCrefBinder:LookupSimpleNameInContainingSymbol(Symbol,bool,String,int,bool,LookupResult,int,byref):this
        -236 (-21.53% of base) : Microsoft.CodeAnalysis.dasm - SuppressMessageAttributeState:IsDiagnosticSuppressed(String,Location,byref):bool:this
        -221 (-4.74% of base) : Microsoft.CodeAnalysis.dasm - MetadataWriter:SerializeTypeReference(ITypeReference,BlobBuilder,bool,bool):this
        -213 (-16.40% of base) : Microsoft.CodeAnalysis.CSharp.dasm - ExplicitInterfaceHelpers:FindExplicitImplementationCollisions(Symbol,Symbol,DiagnosticBag)
        -187 (-15.33% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - ClsComplianceChecker:VisitMethod(MethodSymbol):this
        -182 (-11.42% of base) : Microsoft.CodeAnalysis.CSharp.dasm - CSharpSyntaxNode:FindTriviaByOffset(SyntaxNode,int,Func`2):SyntaxTrivia
        -177 (-23.79% of base) : System.Reflection.MetadataLoadContext.dasm - EcmaModule:ComputeEntryPoint(bool):MethodInfo:this
        -163 (-45.40% of base) : System.Reflection.Metadata.dasm - <GetTypesWithProperties>d__12:MoveNext():bool:this
        -163 (-45.40% of base) : System.Reflection.Metadata.dasm - <GetTypesWithEvents>d__13:MoveNext():bool:this
        -136 (-25.47% of base) : Microsoft.CodeAnalysis.dasm - <GetEffectiveDiagnostics>d__66:MoveNext():bool:this
        -136 (-12.08% of base) : System.Threading.Channels.dasm - UnboundedChannelWriter:TryWrite(__Canon):bool:this (2 methods)
        -136 (-12.22% of base) : System.Threading.Channels.dasm - UnboundedChannelWriter:TryWrite(ubyte):bool:this (2 methods)
        -136 (-12.21% of base) : System.Threading.Channels.dasm - UnboundedChannelWriter:TryWrite(short):bool:this (2 methods)
        -136 (-12.32% of base) : System.Threading.Channels.dasm - UnboundedChannelWriter:TryWrite(int):bool:this (2 methods)
        -136 (-12.22% of base) : System.Threading.Channels.dasm - UnboundedChannelWriter:TryWrite(double):bool:this (2 methods)
        -136 (-8.01% of base) : System.Threading.Channels.dasm - UnboundedChannelWriter:TryWrite(Vector`1):bool:this (2 methods)
Top method regressions (percentages):
          79 ( 6.76% of base) : System.Private.CoreLib.dasm - ManifestBuilder:TranslateToManifestConvention(String,String):String:this
          21 ( 3.39% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Parser:ParseXmlMarkupDecl(SyntaxListBuilder`1):this
           9 ( 1.53% of base) : System.Private.Xml.dasm - TailCallAnalyzer:AnalyzeDefinition(QilNode)
          13 ( 1.52% of base) : Newtonsoft.Json.dasm - JPath:TryParseValue(byref):bool:this
           5 ( 0.52% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Parser:ParseNamedArguments(SeparatedSyntaxListBuilder`1):this
           1 ( 0.04% of base) : System.Text.Encoding.CodePages.dasm - GB18030Encoding:GetChars(long,int,long,int,DecoderNLS):int:this
Top method improvements (percentages):
        -116 (-52.49% of base) : ILCompiler.Reflection.ReadyToRun.dasm - AllEntriesEnumerator:GetNext():NativeParser:this
        -282 (-46.53% of base) : Microsoft.CodeAnalysis.CSharp.dasm - Binder:BindQueryInternal2(QueryTranslationState,DiagnosticBag):BoundExpression:this
        -163 (-45.40% of base) : System.Reflection.Metadata.dasm - <GetTypesWithProperties>d__12:MoveNext():bool:this
        -163 (-45.40% of base) : System.Reflection.Metadata.dasm - <GetTypesWithEvents>d__13:MoveNext():bool:this
         -59 (-44.70% of base) : System.Drawing.Common.dasm - Graphics:PopContext(int):this
        -358 (-40.09% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Binder:CheckParameterNameNotDuplicate(ArrayBuilder`1,int,ParameterSyntax,ParameterSymbol,DiagnosticBag):this
         -63 (-34.62% of base) : System.Security.Cryptography.Cng.dasm - CngKey:Delete():this
         -46 (-30.87% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - Scanner:EatThroughLine():this
        -109 (-26.33% of base) : Microsoft.CodeAnalysis.CSharp.dasm - DiagnosticsPass:CheckVacuousComparisons(BoundBinaryOperator,ConstantValue,BoundNode):this
        -136 (-25.47% of base) : Microsoft.CodeAnalysis.dasm - <GetEffectiveDiagnostics>d__66:MoveNext():bool:this
        -127 (-25.05% of base) : Microsoft.CodeAnalysis.dasm - SyntaxNodeOrToken:GetNextSiblingWithSearch(ChildSyntaxList):SyntaxNodeOrToken:this
        -177 (-23.79% of base) : System.Reflection.MetadataLoadContext.dasm - EcmaModule:ComputeEntryPoint(bool):MethodInfo:this
         -37 (-22.56% of base) : Microsoft.Diagnostics.Tracing.TraceEvent.dasm - <GetEnumerable>d__15:MoveNext():bool:this
        -134 (-22.04% of base) : Microsoft.CodeAnalysis.CSharp.dasm - Lexer:ScanXmlAttributeText(byref):this
        -236 (-21.53% of base) : Microsoft.CodeAnalysis.dasm - SuppressMessageAttributeState:IsDiagnosticSuppressed(String,Location,byref):bool:this
        -243 (-20.82% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - DocumentationCommentCrefBinder:LookupSimpleNameInContainingSymbol(Symbol,bool,String,int,bool,LookupResult,int,byref):this
        -102 (-20.52% of base) : Microsoft.CodeAnalysis.CSharp.dasm - Lexer:ScanXmlProcessingInstructionText(byref):this
        -102 (-20.52% of base) : Microsoft.CodeAnalysis.CSharp.dasm - Lexer:ScanXmlCommentText(byref):this
         -73 (-20.51% of base) : Microsoft.CodeAnalysis.dasm - SwitchIntegralJumpTableEmitter:EmitSwitchBuckets(ImmutableArray`1,int,int):this
         -82 (-20.40% of base) : System.Private.Xml.dasm - XmlSubtreeReader:Read():bool:this
106 total methods with Code Size differences (100 improved, 6 regressed), 243053 unchanged.

[erozenfeld]

@dotnet/jit-contrib @AndyAyersMS PTAL

[CarolEidt]

will pInlineInfo->retBB always be non-null if bottomBlock != nullptr?

[erozenfeld]

pInlineInfo->retBB is non-null if pInlineInfo->retExpr is non null and we have a noway_assert(pInlineInfo->retExpr)` above.

[erozenfeld]

I decided to change my fix to update the basic block flags later in fgUpdateInlineReturnExpressionPlaceHolder when we replace GT_RET_EXPR with the tree from the inlinee. I think it's a cleaner fix even though it requires more plumbing. I also added a comment.
The diffs are the same as with the previous version of the fix.
@CarolEidt @AndyAyersMS PTAL

[BruceForstall]

LGTM

[AndyAyersMS]

LGTM.