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JIT: simple redundant compare optimization#43811

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Merged

AndyAyersMS merged 2 commits intodotnet:masterfromAndyAyersMS:RedundantBranches

Nov 4, 2020

Merged

JIT: simple redundant compare optimization#43811

AndyAyersMS merged 2 commits intodotnet:masterfromAndyAyersMS:RedundantBranches

Nov 4, 2020

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AndyAyersMS commentedOct 25, 2020

For a relop, walk up the dominator tree to see if any dominating
block has a similar compare. If so, and there's just one path from
that block to the relop, the relop's value is known.

Closes#11909.

JIT: simple redundant compare optimization

fc57631

For a relop, walk up the dominator tree to see if any dominatingblock has a similar compare. If so, and there's just one path fromthat block to the relop, the relop's value is known.Closesdotnet#11909.

Dotnet-GitSync-Bot added the area-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label

Oct 25, 2020

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AndyAyersMS commentedOct 25, 2020

@briansull PTAL.
cc @dotnet/jit-contrib

This will eventually feed into optimizing redundant class checks we'll see in dynamic PGO.

PMI CodeSize Diffs for System.Private.CoreLib.dll, framework assemblies for x64 default jitSummary of Code Size diffs:(Lower is better)Total bytes of base: 50312241Total bytes of diff: 50302279Total bytes of delta: -9962 (-0.02% of base)    diff is an improvement.Top file improvements (bytes):       -4129 : System.Data.Common.dasm (-0.28% of base)       -3542 : FSharp.Core.dasm (-0.11% of base)        -637 : System.Private.CoreLib.dasm (-0.01% of base)        -274 : Microsoft.CodeAnalysis.CSharp.dasm (-0.01% of base)        -258 : Microsoft.CodeAnalysis.VisualBasic.dasm (-0.00% of base)        -154 : System.Text.Json.dasm (-0.03% of base)        -104 : System.Security.Cryptography.Pkcs.dasm (-0.03% of base)         -89 : Microsoft.Extensions.DependencyModel.dasm (-0.19% of base)         -75 : System.Formats.Asn1.dasm (-0.08% of base)         -63 : System.Net.Http.dasm (-0.01% of base)         -61 : System.DirectoryServices.AccountManagement.dasm (-0.02% of base)         -59 : System.Linq.Expressions.dasm (-0.01% of base)         -38 : Microsoft.Extensions.Logging.Console.dasm (-0.09% of base)         -36 : System.Diagnostics.Process.dasm (-0.04% of base)         -35 : Microsoft.Diagnostics.Tracing.TraceEvent.dasm (-0.00% of base)         -33 : System.Private.Xml.dasm (-0.00% of base)         -30 : System.Memory.dasm (-0.01% of base)         -28 : System.Text.Encodings.Web.dasm (-0.09% of base)         -27 : System.Security.Cryptography.Algorithms.dasm (-0.01% of base)         -27 : System.Security.Cryptography.Cng.dasm (-0.02% of base)42 total files with Code Size differences (42 improved, 0 regressed), 226 unchanged.Top method improvements (bytes):        -529 (-14.86% of base) : System.Data.Common.dasm - SqlDoubleStorage:Aggregate(ref,int):Object:this        -449 (-12.49% of base) : System.Data.Common.dasm - SqlSingleStorage:Aggregate(ref,int):Object:this        -446 (-13.78% of base) : System.Data.Common.dasm - SqlInt16Storage:Aggregate(ref,int):Object:this        -446 (-13.79% of base) : System.Data.Common.dasm - SqlInt32Storage:Aggregate(ref,int):Object:this        -446 (-12.31% of base) : System.Data.Common.dasm - SqlInt64Storage:Aggregate(ref,int):Object:this        -446 (-11.65% of base) : System.Data.Common.dasm - SqlMoneyStorage:Aggregate(ref,int):Object:this        -446 (-13.72% of base) : System.Data.Common.dasm - SqlByteStorage:Aggregate(ref,int):Object:this        -440 (-11.14% of base) : System.Data.Common.dasm - SqlDecimalStorage:Aggregate(ref,int):Object:this        -203 (-5.40% of base) : System.Private.CoreLib.dasm - TextInfo:ChangeCaseCommon(String):String:this (7 methods)        -151 (-44.41% of base) : System.Data.Common.dasm - DataTable:FindByIndex(Index,ref):DataRow:this        -139 (-20.20% of base) : System.Data.Common.dasm - DataView:System.ComponentModel.IBindingList.Find(PropertyDescriptor,Object):int:this        -134 (-9.48% of base) : System.Data.Common.dasm - DataTable:LoadRow(ref,int,Index):DataRow:this        -130 (-20.57% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkEqualsQmark(Nullable`1,Nullable`1):bool (6 methods)        -127 (-12.99% of base) : System.Private.CoreLib.dasm - Vector128`1:<Equals>g__SoftwareFallback|12_0(byref,Vector128`1):bool (6 methods)         -95 (-21.16% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkGreaterEqualsQmark(Nullable`1,Nullable`1):bool (6 methods)         -95 (-21.16% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkGreaterQmark(Nullable`1,Nullable`1):bool (6 methods)         -95 (-21.16% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkLessEqualsQmark(Nullable`1,Nullable`1):bool (6 methods)         -95 (-21.16% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkLessQmark(Nullable`1,Nullable`1):bool (6 methods)         -87 (-10.48% of base) : System.Private.CoreLib.dasm - Vector256`1:<Equals>g__SoftwareFallback|14_0(byref,Vector256`1):bool (6 methods)         -82 (-3.63% of base) : Microsoft.CodeAnalysis.VisualBasic.dasm - CodeGenerator:EmitTryCastExpression(BoundTryCast,bool):thisTop method improvements (percentages):         -22 (-50.00% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkGreaterEquals(Nullable`1,long):bool         -22 (-50.00% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkGreater(Nullable`1,long):bool         -22 (-50.00% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkLessEquals(Nullable`1,long):bool         -22 (-50.00% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkLess(Nullable`1,long):bool         -22 (-50.00% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkEquals(Nullable`1,long):bool         -22 (-50.00% of base) : FSharp.Core.dasm - NullableOperators:op_GreaterEqualsQmark(long,Nullable`1):bool         -22 (-50.00% of base) : FSharp.Core.dasm - NullableOperators:op_GreaterQmark(long,Nullable`1):bool         -22 (-50.00% of base) : FSharp.Core.dasm - NullableOperators:op_LessEqualsQmark(long,Nullable`1):bool         -22 (-50.00% of base) : FSharp.Core.dasm - NullableOperators:op_LessQmark(long,Nullable`1):bool         -22 (-50.00% of base) : FSharp.Core.dasm - NullableOperators:op_EqualsQmark(long,Nullable`1):bool         -22 (-45.83% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkGreaterEquals(Nullable`1,double):bool         -22 (-45.83% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkGreater(Nullable`1,double):bool         -22 (-45.83% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkLessEquals(Nullable`1,double):bool         -22 (-45.83% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkLess(Nullable`1,double):bool         -22 (-45.83% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkEquals(Nullable`1,int):bool         -22 (-45.83% of base) : FSharp.Core.dasm - NullableOperators:op_QmarkEquals(Nullable`1,double):bool         -22 (-45.83% of base) : FSharp.Core.dasm - NullableOperators:op_GreaterEqualsQmark(double,Nullable`1):bool         -22 (-45.83% of base) : FSharp.Core.dasm - NullableOperators:op_GreaterQmark(double,Nullable`1):bool         -22 (-45.83% of base) : FSharp.Core.dasm - NullableOperators:op_LessEqualsQmark(double,Nullable`1):bool         -22 (-45.83% of base) : FSharp.Core.dasm - NullableOperators:op_LessQmark(double,Nullable`1):bool257 total methods with Code Size differences (257 improved, 0 regressed), 258511 unchanged.

Diff from#11909

; Assembly listing for method String:EndsWith(String,int):bool:this;; BEFOREG_M26632_IG11:movebx, dword ptr[rdi+8]movr8d,ebxsubr8d,r9dcmpebx,r8djb       SHORT G_M26632_IG16cmpebx,r8djb       G_M26632_IG22G_M26632_IG12:addrdi,12;; AFTERG_M26632_IG11:movebx, dword ptr[rdi+8]movr8d,ebxsubr8d,r9dcmpebx,r8djb       SHORT G_M26632_IG15addrdi,12

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AndyAyersMS commentedOct 25, 2020

Note it feels a bit odd to be doing this opt here, as it's not strictly related to assertion prop, but it doesn't seem to warrant its own phase. Feel free to suggest a better home.