[JitDiff X64] [hez2010] JIT: Always use CallInfo method handle for devirtual ...

[MihuBot]

Job completed in 16 minutes 15 seconds (remote runner delay: 1 minute 14 seconds).
dotnet/runtime#123434

Main commit: dotnet/runtime@b593e13
PR commit: hez2010/runtime@b510b8e

Diffs

Diffs

Found 87 files with textual diffs.

Summary of Code Size diffs:
(Lower is better)

Total bytes of base: 45296843
Total bytes of diff: 45295345
Total bytes of delta: -1498 (-0.00 % of base)
Total relative delta: Infinity
    diff is an improvement.
    relative diff is a regression.


Top file regressions (bytes):
         109 : System.DirectoryServices.Protocols.dasm (0.07 % of base)

Top file improvements (bytes):
       -1231 : System.Collections.Immutable.dasm (-0.05 % of base)
        -137 : System.Private.CoreLib.dasm (-0.00 % of base)
        -111 : System.Collections.dasm (-0.02 % of base)
         -73 : System.Linq.Parallel.dasm (-0.00 % of base)
         -55 : System.Text.Json.dasm (-0.00 % of base)

6 total files with Code Size differences (5 improved, 1 regressed), 254 unchanged.

Top method regressions (bytes):
         109 (Infinity of base) : System.DirectoryServices.Protocols.dasm - System.DirectoryServices.Protocols.PartialResultsRetriever:ThreadRoutine():this (FullOpts)
          34 (46.58 % of base) : System.Linq.Parallel.dasm - System.Linq.Parallel.ListChunk`1[System.__Canon]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
          34 (46.58 % of base) : System.Linq.Parallel.dasm - System.Linq.Parallel.Lookup`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
           5 (2.53 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Keys():System.Collections.Generic.ICollection`1[System.__Canon]:this (FullOpts)
           5 (2.53 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Values():System.Collections.Generic.ICollection`1[System.Nullable`1[int]]:this (FullOpts)
           5 (2.53 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Keys():System.Collections.ICollection:this (FullOpts)
           5 (2.53 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Values():System.Collections.ICollection:this (FullOpts)

Top method improvements (bytes):
        -191 (-52.91 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:Replace(System.__Canon,System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
        -190 (-71.70 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
        -190 (-71.70 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.Immutable.IImmutableList<T>.Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.IImmutableList`1[System.__Canon]:this (FullOpts)
        -188 (-55.13 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
        -179 (-59.87 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:IndexOf(System.__Canon):int:this (FullOpts)
        -173 (-44.70 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.IList.IndexOf(System.Object):int:this (FullOpts)
         -65 (-8.49 % of base) : System.Linq.Parallel.dasm - System.Linq.Parallel.DefaultMergeHelper`2[System.__Canon,System.Nullable`1[int]]:GetResultsAsArray():System.__Canon[]:this (FullOpts)
         -63 (-57.80 % of base) : System.Private.CoreLib.dasm - System.ArraySegment`1[System.__Canon]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
         -55 (-21.91 % of base) : System.Text.Json.dasm - System.Text.Json.Serialization.Metadata.ReflectionEmitCachingMemberAccessor+Cache`1[System.__Canon]:EvictStaleCacheEntries(long):this (FullOpts)
         -38 (-3.16 % of base) : System.Linq.Parallel.dasm - System.Linq.Parallel.ElementAtQueryOperator`1[System.__Canon]:Aggregate(byref,bool):bool:this (FullOpts)
         -38 (-50.67 % of base) : System.Linq.Parallel.dasm - System.Linq.Parallel.QueryOpeningEnumerator`1[System.__Canon]:System.Collections.IEnumerator.get_Current():System.Object:this (FullOpts)
         -37 (-50.68 % of base) : System.Private.CoreLib.dasm - System.Collections.Generic.Dictionary`2+KeyCollection[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
         -37 (-50.68 % of base) : System.Collections.dasm - System.Collections.Generic.OrderedDictionary`2+KeyCollection[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
         -37 (-50.68 % of base) : System.Collections.dasm - System.Collections.Generic.PriorityQueue`2+UnorderedItemsCollection[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
         -37 (-50.68 % of base) : System.Collections.dasm - System.Collections.Generic.SortedDictionary`2+KeyCollection[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
         -37 (-50.68 % of base) : System.Private.CoreLib.dasm - System.Runtime.CompilerServices.ConditionalWeakTable`2[System.__Canon,System.__Canon]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
         -35 (-17.68 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableSortedDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Keys():System.Collections.Generic.ICollection`1[System.__Canon]:this (FullOpts)
         -35 (-17.68 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableSortedDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Values():System.Collections.Generic.ICollection`1[System.Nullable`1[int]]:this (FullOpts)
         -35 (-17.68 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableSortedDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Keys():System.Collections.ICollection:this (FullOpts)
         -35 (-17.68 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableSortedDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Values():System.Collections.ICollection:this (FullOpts)

Top method regressions (percentages):
         109 (Infinity of base) : System.DirectoryServices.Protocols.dasm - System.DirectoryServices.Protocols.PartialResultsRetriever:ThreadRoutine():this (FullOpts)
          34 (46.58 % of base) : System.Linq.Parallel.dasm - System.Linq.Parallel.ListChunk`1[System.__Canon]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
          34 (46.58 % of base) : System.Linq.Parallel.dasm - System.Linq.Parallel.Lookup`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
           5 (2.53 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Keys():System.Collections.Generic.ICollection`1[System.__Canon]:this (FullOpts)
           5 (2.53 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Values():System.Collections.Generic.ICollection`1[System.Nullable`1[int]]:this (FullOpts)
           5 (2.53 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Keys():System.Collections.ICollection:this (FullOpts)
           5 (2.53 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Values():System.Collections.ICollection:this (FullOpts)

Top method improvements (percentages):
        -190 (-71.70 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
        -190 (-71.70 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.Immutable.IImmutableList<T>.Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.IImmutableList`1[System.__Canon]:this (FullOpts)
        -179 (-59.87 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:IndexOf(System.__Canon):int:this (FullOpts)
         -63 (-57.80 % of base) : System.Private.CoreLib.dasm - System.ArraySegment`1[System.__Canon]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
        -188 (-55.13 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
        -191 (-52.91 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:Replace(System.__Canon,System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
         -37 (-50.68 % of base) : System.Private.CoreLib.dasm - System.Collections.Generic.Dictionary`2+KeyCollection[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
         -37 (-50.68 % of base) : System.Collections.dasm - System.Collections.Generic.OrderedDictionary`2+KeyCollection[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
         -37 (-50.68 % of base) : System.Collections.dasm - System.Collections.Generic.PriorityQueue`2+UnorderedItemsCollection[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
         -37 (-50.68 % of base) : System.Collections.dasm - System.Collections.Generic.SortedDictionary`2+KeyCollection[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
         -37 (-50.68 % of base) : System.Private.CoreLib.dasm - System.Runtime.CompilerServices.ConditionalWeakTable`2[System.__Canon,System.__Canon]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
         -38 (-50.67 % of base) : System.Linq.Parallel.dasm - System.Linq.Parallel.QueryOpeningEnumerator`1[System.__Canon]:System.Collections.IEnumerator.get_Current():System.Object:this (FullOpts)
        -173 (-44.70 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.IList.IndexOf(System.Object):int:this (FullOpts)
         -55 (-21.91 % of base) : System.Text.Json.dasm - System.Text.Json.Serialization.Metadata.ReflectionEmitCachingMemberAccessor+Cache`1[System.__Canon]:EvictStaleCacheEntries(long):this (FullOpts)
         -35 (-17.68 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableSortedDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Keys():System.Collections.Generic.ICollection`1[System.__Canon]:this (FullOpts)
         -35 (-17.68 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableSortedDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Values():System.Collections.Generic.ICollection`1[System.Nullable`1[int]]:this (FullOpts)
         -35 (-17.68 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableSortedDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Keys():System.Collections.ICollection:this (FullOpts)
         -35 (-17.68 % of base) : System.Collections.Immutable.dasm - System.Collections.Immutable.ImmutableSortedDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Values():System.Collections.ICollection:this (FullOpts)
         -65 (-8.49 % of base) : System.Linq.Parallel.dasm - System.Linq.Parallel.DefaultMergeHelper`2[System.__Canon,System.Nullable`1[int]]:GetResultsAsArray():System.__Canon[]:this (FullOpts)
         -38 (-3.16 % of base) : System.Linq.Parallel.dasm - System.Linq.Parallel.ElementAtQueryOperator`1[System.__Canon]:Aggregate(byref,bool):bool:this (FullOpts)

27 total methods with Code Size differences (20 improved, 7 regressed), 283478 unchanged.

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

Artifacts:

• jit-diffs-main.zip (154 MB)
• jit-diffs-pr.zip (154 MB)
• diff-frameworks.txt (13 KB)
• ShortDiffsRegressions.md (41 KB)
• ShortDiffsImprovements.md (59 KB)
• LongDiffsImprovements.md (175 KB)

[MihuBot]

Top method regressions

34 (46.58 % of base) - System.Linq.Parallel.ListChunk`1[System.__Canon]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this

 ; Assembly listing for method System.Linq.Parallel.ListChunk`1[System.__Canon]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
 ; rbp based frame
-; fully interruptible
+; partially interruptible
 ; No PGO data
+; 0 inlinees with PGO data; 3 single block inlinees; 0 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T00] (  4,  4   )     ref  ->  rbx         this class-hnd single-def <System.Linq.Parallel.ListChunk`1[System.__Canon]>
+;  V00 this         [V00,T01] (  4,  4   )     ref  ->  rbx         this class-hnd single-def <System.Linq.Parallel.ListChunk`1[System.__Canon]>
 ;# V01 OutArgs      [V01    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
-;  V02 tmp1         [V02,T01] (  4,  6   )    long  ->  r11         "spilling helperCall"
-;  V03 rat0         [V03,T03] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V04 rat1         [V04,T02] (  3,  5.60)    long  ->  r11         "fgMakeTemp is creating a new local variable"
+;* V02 tmp1         [V02    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V03 tmp2         [V03,T00] (  4,  8   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.Linq.Parallel.ListChunk`1+<GetEnumerator>d__10[System.__Canon]>
+;* V04 tmp3         [V04    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V05 cse0         [V05,T04] (  3,  2.20)    long  ->  rdi         "CSE #01: aggressive"
+;  V06 rat0         [V06,T03] (  3,  4   )    long  ->  rsi         "runtime lookup"
+;  V07 rat1         [V07,T02] (  3,  5.60)    long  ->  rsi         "fgMakeTemp is creating a new local variable"
 ;
-; Lcl frame size = 8
+; Lcl frame size = 16
 
 G_M36131_IG01:
        push     rbp
+       push     r15
        push     rbx
-       push     rax
-       lea      rbp, [rsp+0x10]
-       mov      qword ptr [rbp-0x10], rdi
+       sub      rsp, 16
+       lea      rbp, [rsp+0x20]
+       mov      qword ptr [rbp-0x18], rdi
        mov      rbx, rdi
-						;; size=15 bbWeight=1 PerfScore 4.75
+						;; size=20 bbWeight=1 PerfScore 5.00
 G_M36131_IG02:
        mov      rdi, qword ptr [rbx]
        mov      rsi, qword ptr [rdi+0x30]
        mov      rsi, qword ptr [rsi]
-       mov      r11, qword ptr [rsi+0x20]
-       test     r11, r11
+       mov      rsi, qword ptr [rsi+0x18]
+       test     rsi, rsi
        je       SHORT G_M36131_IG05
 						;; size=19 bbWeight=1 PerfScore 9.25
 G_M36131_IG03:
-       mov      rdi, rbx
-						;; size=3 bbWeight=1 PerfScore 0.25
+       mov      rdi, rsi
+       call     CORINFO_HELP_NEWSFAST
+       mov      r15, rax
+       xor      edi, edi
+       mov      dword ptr [r15+0x20], edi
+       lea      rdi, bword ptr [r15+0x10]
+       mov      rsi, rbx
+       call     CORINFO_HELP_ASSIGN_REF
+       mov      rax, r15
+						;; size=32 bbWeight=1 PerfScore 4.75
 G_M36131_IG04:
-       add      rsp, 8
+       add      rsp, 16
        pop      rbx
+       pop      r15
        pop      rbp
-       tail.jmp [r11]
-						;; size=9 bbWeight=1 PerfScore 5.25
+       ret      
+						;; size=9 bbWeight=1 PerfScore 2.75
 G_M36131_IG05:
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r11, rax
+       mov      rsi, rax
        jmp      SHORT G_M36131_IG03
 						;; size=27 bbWeight=0.20 PerfScore 1.15
 
-; Total bytes of code 73, prolog size 15, PerfScore 20.65, instruction count 22, allocated bytes for code 73 (MethodHash=fca972dc) for method System.Linq.Parallel.ListChunk`1[System.__Canon]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
+; Total bytes of code 107, prolog size 17, PerfScore 22.90, instruction count 32, allocated bytes for code 107 (MethodHash=fca972dc) for method System.Linq.Parallel.ListChunk`1[System.__Canon]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
 ; ============================================================

34 (46.58 % of base) - System.Linq.Parallel.Lookup`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this

 ; Assembly listing for method System.Linq.Parallel.Lookup`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
 ; rbp based frame
-; fully interruptible
+; partially interruptible
 ; No PGO data
+; 0 inlinees with PGO data; 3 single block inlinees; 0 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T00] (  4,  4   )     ref  ->  rbx         this class-hnd single-def <System.Linq.Parallel.Lookup`2[System.__Canon,System.Nullable`1[int]]>
+;  V00 this         [V00,T01] (  4,  4   )     ref  ->  rbx         this class-hnd single-def <System.Linq.Parallel.Lookup`2[System.__Canon,System.Nullable`1[int]]>
 ;# V01 OutArgs      [V01    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
-;  V02 tmp1         [V02,T01] (  4,  6   )    long  ->  r11         "spilling helperCall"
-;  V03 rat0         [V03,T03] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V04 rat1         [V04,T02] (  3,  5.60)    long  ->  r11         "fgMakeTemp is creating a new local variable"
+;* V02 tmp1         [V02    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V03 tmp2         [V03,T00] (  4,  8   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.Linq.Parallel.Lookup`2+<GetEnumerator>d__10[System.__Canon,System.Nullable`1[int]]>
+;* V04 tmp3         [V04    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V05 cse0         [V05,T04] (  3,  2.20)    long  ->  rdi         "CSE #01: aggressive"
+;  V06 rat0         [V06,T03] (  3,  4   )    long  ->  rsi         "runtime lookup"
+;  V07 rat1         [V07,T02] (  3,  5.60)    long  ->  rsi         "fgMakeTemp is creating a new local variable"
 ;
-; Lcl frame size = 8
+; Lcl frame size = 16
 
 G_M20073_IG01:
        push     rbp
+       push     r15
        push     rbx
-       push     rax
-       lea      rbp, [rsp+0x10]
-       mov      qword ptr [rbp-0x10], rdi
+       sub      rsp, 16
+       lea      rbp, [rsp+0x20]
+       mov      qword ptr [rbp-0x18], rdi
        mov      rbx, rdi
-						;; size=15 bbWeight=1 PerfScore 4.75
+						;; size=20 bbWeight=1 PerfScore 5.00
 G_M20073_IG02:
        mov      rdi, qword ptr [rbx]
        mov      rsi, qword ptr [rdi+0x30]
        mov      rsi, qword ptr [rsi]
-       mov      r11, qword ptr [rsi+0x30]
-       test     r11, r11
+       mov      rsi, qword ptr [rsi+0x28]
+       test     rsi, rsi
        je       SHORT G_M20073_IG05
 						;; size=19 bbWeight=1 PerfScore 9.25
 G_M20073_IG03:
-       mov      rdi, rbx
-						;; size=3 bbWeight=1 PerfScore 0.25
+       mov      rdi, rsi
+       call     CORINFO_HELP_NEWSFAST
+       mov      r15, rax
+       xor      edi, edi
+       mov      dword ptr [r15+0x18], edi
+       lea      rdi, bword ptr [r15+0x10]
+       mov      rsi, rbx
+       call     CORINFO_HELP_ASSIGN_REF
+       mov      rax, r15
+						;; size=32 bbWeight=1 PerfScore 4.75
 G_M20073_IG04:
-       add      rsp, 8
+       add      rsp, 16
        pop      rbx
+       pop      r15
        pop      rbp
-       tail.jmp [r11]
-						;; size=9 bbWeight=1 PerfScore 5.25
+       ret      
+						;; size=9 bbWeight=1 PerfScore 2.75
 G_M20073_IG05:
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r11, rax
+       mov      rsi, rax
        jmp      SHORT G_M20073_IG03
 						;; size=27 bbWeight=0.20 PerfScore 1.15
 
-; Total bytes of code 73, prolog size 15, PerfScore 20.65, instruction count 22, allocated bytes for code 73 (MethodHash=478fb196) for method System.Linq.Parallel.Lookup`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
+; Total bytes of code 107, prolog size 17, PerfScore 22.90, instruction count 32, allocated bytes for code 107 (MethodHash=478fb196) for method System.Linq.Parallel.Lookup`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator:this (FullOpts)
 ; ============================================================

5 (2.53 % of base) - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary.get_Keys():System.Collections.Generic.ICollection`1[System.__Canon]:this

 ; Assembly listing for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Keys():System.Collections.Generic.ICollection`1[System.__Canon]:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
 ; rbp based frame
 ; partially interruptible
 ; No PGO data
-; 0 inlinees with PGO data; 3 single block inlinees; 2 inlinees without PGO data
+; 0 inlinees with PGO data; 6 single block inlinees; 2 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T01] (  5,  5   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]>
+;  V00 this         [V00,T02] (  5,  5   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]>
 ;# V01 OutArgs      [V01    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
-;  V02 tmp1         [V02,T00] (  5, 10   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.KeysCollectionAccessor`2[System.__Canon,System.Nullable`1[int]]>
+;  V02 tmp1         [V02,T01] (  4,  8   )     ref  ->  r14         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.KeysCollectionAccessor`2[System.__Canon,System.Nullable`1[int]]>
 ;* V03 tmp2         [V03    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V04 tmp3         [V04,T02] (  4,  6   )    long  ->  r11         "spilling helperCall"
-;* V05 tmp4         [V05    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V06 tmp5         [V06,T03] (  3,  6   )     ref  ->  r14         class-hnd single-def "Inlining Arg" <System.Collections.Generic.IEnumerable`1[System.__Canon]>
+;* V04 tmp3         [V04    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V05 tmp4         [V05,T00] (  5, 10   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.ImmutableDictionary`2+<get_Keys>d__25[System.__Canon,System.Nullable`1[int]]>
+;* V06 tmp5         [V06    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
 ;* V07 tmp6         [V07    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V08 rat0         [V08,T06] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V09 rat1         [V09,T08] (  3,  4   )    long  ->  rsi         "runtime lookup"
-;  V10 rat2         [V10,T04] (  3,  5.60)    long  ->  rsi         "fgMakeTemp is creating a new local variable"
-;  V11 rat3         [V11,T07] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V12 rat4         [V12,T05] (  3,  5.60)    long  ->  r11         "fgMakeTemp is creating a new local variable"
+;* V08 tmp7         [V08    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V09 cse0         [V09,T07] (  5,  3.40)    long  ->  r15         "CSE #01: aggressive"
+;  V10 rat0         [V10,T05] (  3,  4   )    long  ->  rdi         "runtime lookup"
+;  V11 rat1         [V11,T03] (  3,  5.60)    long  ->  rdi         "fgMakeTemp is creating a new local variable"
+;  V12 rat2         [V12,T06] (  3,  4   )    long  ->  rdi         "runtime lookup"
+;  V13 rat3         [V13,T04] (  3,  5.60)    long  ->  rdi         "fgMakeTemp is creating a new local variable"
 ;
 ; Lcl frame size = 8
 
 G_M38879_IG01:
        push     rbp
        push     r15
        push     r14
        push     rbx
        push     rax
        lea      rbp, [rsp+0x20]
        mov      qword ptr [rbp-0x20], rdi
        mov      rbx, rdi
 						;; size=19 bbWeight=1 PerfScore 6.75
 G_M38879_IG02:
-       mov      rdi, qword ptr [rbx]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi]
-       mov      rsi, qword ptr [rsi+0x68]
-       test     rsi, rsi
+       mov      r15, qword ptr [rbx]
+       mov      rdi, qword ptr [r15+0x30]
+       mov      rdi, qword ptr [rdi]
+       mov      rdi, qword ptr [rdi+0x68]
+       test     rdi, rdi
        je       SHORT G_M38879_IG06
 						;; size=19 bbWeight=1 PerfScore 9.25
 G_M38879_IG03:
-       mov      rdi, rsi
+       call     CORINFO_HELP_NEWSFAST
+       mov      r14, rax
+       mov      rdi, qword ptr [r15+0x30]
+       mov      rdi, qword ptr [rdi]
+       mov      rdi, qword ptr [rdi+0x58]
+       test     rdi, rdi
+       je       SHORT G_M38879_IG07
+						;; size=24 bbWeight=1 PerfScore 8.50
+G_M38879_IG04:
        call     CORINFO_HELP_NEWSFAST
        mov      r15, rax
-       mov      rdi, qword ptr [r15]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi+0x08]
-       mov      r11, qword ptr [rsi+0x18]
-       test     r11, r11
-       je       SHORT G_M38879_IG07
-						;; size=31 bbWeight=1 PerfScore 10.75
-G_M38879_IG04:
-       mov      rdi, rbx
-       call     [r11]
-       mov      r14, rax
-       test     r14, r14
-       je       SHORT G_M38879_IG08
-       lea      rdi, bword ptr [r15+0x08]
+       mov      dword ptr [r15+0x18], -2
+       call     System.Environment:get_CurrentManagedThreadId():int
+       mov      dword ptr [r15+0x1C], eax
+       lea      rdi, bword ptr [r15+0x10]
        mov      rsi, rbx
        call     CORINFO_HELP_ASSIGN_REF
-       lea      rdi, bword ptr [r15+0x10]
-       mov      rsi, r14
+       lea      rdi, bword ptr [r14+0x08]
+       mov      rsi, rbx
        call     CORINFO_HELP_ASSIGN_REF
-       mov      rax, r15
-						;; size=41 bbWeight=1 PerfScore 8.50
+       lea      rdi, bword ptr [r14+0x10]
+       mov      rsi, r15
+       call     CORINFO_HELP_ASSIGN_REF
+       mov      rax, r14
+						;; size=64 bbWeight=1 PerfScore 9.75
 G_M38879_IG05:
        add      rsp, 8
        pop      rbx
        pop      r14
        pop      r15
        pop      rbp
        ret      
 						;; size=11 bbWeight=1 PerfScore 3.25
 G_M38879_IG06:
+       mov      rdi, r15
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      rsi, rax
-       jmp      SHORT G_M38879_IG03
-						;; size=27 bbWeight=0.20 PerfScore 1.15
+       mov      rdi, rax
+       jmp      G_M38879_IG03
+						;; size=33 bbWeight=0.20 PerfScore 1.20
 G_M38879_IG07:
+       mov      rdi, r15
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r11, rax
-       jmp      SHORT G_M38879_IG04
-						;; size=27 bbWeight=0.20 PerfScore 1.15
-G_M38879_IG08:
-       mov      rdi, 0xD1FFAB1E      ; 'keysOrValues'
-       mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.Requires:FailArgumentNullException(System.String)
-       call     [rax]System.Collections.Immutable.Requires:FailArgumentNullException(System.String)
-       int3     
-						;; size=23 bbWeight=0 PerfScore 0.00
+       mov      rdi, rax
+       jmp      G_M38879_IG04
+						;; size=33 bbWeight=0.20 PerfScore 1.20
 
-; Total bytes of code 198, prolog size 16, PerfScore 40.80, instruction count 55, allocated bytes for code 198 (MethodHash=401e6820) for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Keys():System.Collections.Generic.ICollection`1[System.__Canon]:this (FullOpts)
+; Total bytes of code 203, prolog size 16, PerfScore 39.90, instruction count 54, allocated bytes for code 203 (MethodHash=401e6820) for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Keys():System.Collections.Generic.ICollection`1[System.__Canon]:this (FullOpts)
 ; ============================================================

5 (2.53 % of base) - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary.get_Values():System.Collections.Generic.ICollection`1[System.Nullable`1[int]]:this

 ; Assembly listing for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Values():System.Collections.Generic.ICollection`1[System.Nullable`1[int]]:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
 ; rbp based frame
 ; partially interruptible
 ; No PGO data
-; 0 inlinees with PGO data; 3 single block inlinees; 2 inlinees without PGO data
+; 0 inlinees with PGO data; 6 single block inlinees; 2 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T01] (  5,  5   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]>
+;  V00 this         [V00,T02] (  5,  5   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]>
 ;# V01 OutArgs      [V01    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
-;  V02 tmp1         [V02,T00] (  5, 10   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.ValuesCollectionAccessor`2[System.__Canon,System.Nullable`1[int]]>
+;  V02 tmp1         [V02,T01] (  4,  8   )     ref  ->  r14         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.ValuesCollectionAccessor`2[System.__Canon,System.Nullable`1[int]]>
 ;* V03 tmp2         [V03    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V04 tmp3         [V04,T02] (  4,  6   )    long  ->  r11         "spilling helperCall"
-;* V05 tmp4         [V05    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V06 tmp5         [V06,T03] (  3,  6   )     ref  ->  r14         class-hnd single-def "Inlining Arg" <System.Collections.Generic.IEnumerable`1[System.Nullable`1[int]]>
-;  V07 rat0         [V07,T06] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V08 rat1         [V08,T08] (  3,  4   )    long  ->  rsi         "runtime lookup"
-;  V09 rat2         [V09,T04] (  3,  5.60)    long  ->  rsi         "fgMakeTemp is creating a new local variable"
-;  V10 rat3         [V10,T07] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V11 rat4         [V11,T05] (  3,  5.60)    long  ->  r11         "fgMakeTemp is creating a new local variable"
+;* V04 tmp3         [V04    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V05 tmp4         [V05,T00] (  5, 10   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.ImmutableDictionary`2+<get_Values>d__27[System.__Canon,System.Nullable`1[int]]>
+;* V06 tmp5         [V06    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V07 tmp6         [V07    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V08 cse0         [V08,T07] (  5,  3.40)    long  ->  r15         "CSE #01: aggressive"
+;  V09 rat0         [V09,T05] (  3,  4   )    long  ->  rdi         "runtime lookup"
+;  V10 rat1         [V10,T03] (  3,  5.60)    long  ->  rdi         "fgMakeTemp is creating a new local variable"
+;  V11 rat2         [V11,T06] (  3,  4   )    long  ->  rdi         "runtime lookup"
+;  V12 rat3         [V12,T04] (  3,  5.60)    long  ->  rdi         "fgMakeTemp is creating a new local variable"
 ;
 ; Lcl frame size = 8
 
 G_M27163_IG01:
        push     rbp
        push     r15
        push     r14
        push     rbx
        push     rax
        lea      rbp, [rsp+0x20]
        mov      qword ptr [rbp-0x20], rdi
        mov      rbx, rdi
 						;; size=19 bbWeight=1 PerfScore 6.75
 G_M27163_IG02:
-       mov      rdi, qword ptr [rbx]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi]
-       mov      rsi, qword ptr [rsi+0x70]
-       test     rsi, rsi
+       mov      r15, qword ptr [rbx]
+       mov      rdi, qword ptr [r15+0x30]
+       mov      rdi, qword ptr [rdi]
+       mov      rdi, qword ptr [rdi+0x70]
+       test     rdi, rdi
        je       SHORT G_M27163_IG06
 						;; size=19 bbWeight=1 PerfScore 9.25
 G_M27163_IG03:
-       mov      rdi, rsi
+       call     CORINFO_HELP_NEWSFAST
+       mov      r14, rax
+       mov      rdi, qword ptr [r15+0x30]
+       mov      rdi, qword ptr [rdi]
+       mov      rdi, qword ptr [rdi+0x60]
+       test     rdi, rdi
+       je       SHORT G_M27163_IG07
+						;; size=24 bbWeight=1 PerfScore 8.50
+G_M27163_IG04:
        call     CORINFO_HELP_NEWSFAST
        mov      r15, rax
-       mov      rdi, qword ptr [r15]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi+0x08]
-       mov      r11, qword ptr [rsi+0x18]
-       test     r11, r11
-       je       SHORT G_M27163_IG07
-						;; size=31 bbWeight=1 PerfScore 10.75
-G_M27163_IG04:
-       mov      rdi, rbx
-       call     [r11]
-       mov      r14, rax
-       test     r14, r14
-       je       SHORT G_M27163_IG08
+       mov      dword ptr [r15+0x10], -2
+       call     System.Environment:get_CurrentManagedThreadId():int
+       mov      dword ptr [r15+0x14], eax
        lea      rdi, bword ptr [r15+0x08]
        mov      rsi, rbx
        call     CORINFO_HELP_ASSIGN_REF
-       lea      rdi, bword ptr [r15+0x10]
-       mov      rsi, r14
+       lea      rdi, bword ptr [r14+0x08]
+       mov      rsi, rbx
        call     CORINFO_HELP_ASSIGN_REF
-       mov      rax, r15
-						;; size=41 bbWeight=1 PerfScore 8.50
+       lea      rdi, bword ptr [r14+0x10]
+       mov      rsi, r15
+       call     CORINFO_HELP_ASSIGN_REF
+       mov      rax, r14
+						;; size=64 bbWeight=1 PerfScore 9.75
 G_M27163_IG05:
        add      rsp, 8
        pop      rbx
        pop      r14
        pop      r15
        pop      rbp
        ret      
 						;; size=11 bbWeight=1 PerfScore 3.25
 G_M27163_IG06:
+       mov      rdi, r15
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      rsi, rax
-       jmp      SHORT G_M27163_IG03
-						;; size=27 bbWeight=0.20 PerfScore 1.15
+       mov      rdi, rax
+       jmp      G_M27163_IG03
+						;; size=33 bbWeight=0.20 PerfScore 1.20
 G_M27163_IG07:
+       mov      rdi, r15
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r11, rax
-       jmp      SHORT G_M27163_IG04
-						;; size=27 bbWeight=0.20 PerfScore 1.15
-G_M27163_IG08:
-       mov      rdi, 0xD1FFAB1E      ; 'keysOrValues'
-       mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.Requires:FailArgumentNullException(System.String)
-       call     [rax]System.Collections.Immutable.Requires:FailArgumentNullException(System.String)
-       int3     
-						;; size=23 bbWeight=0 PerfScore 0.00
+       mov      rdi, rax
+       jmp      G_M27163_IG04
+						;; size=33 bbWeight=0.20 PerfScore 1.20
 
-; Total bytes of code 198, prolog size 16, PerfScore 40.80, instruction count 55, allocated bytes for code 198 (MethodHash=30bf95e4) for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Values():System.Collections.Generic.ICollection`1[System.Nullable`1[int]]:this (FullOpts)
+; Total bytes of code 203, prolog size 16, PerfScore 39.90, instruction count 54, allocated bytes for code 203 (MethodHash=30bf95e4) for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.Generic.IDictionary<TKey,TValue>.get_Values():System.Collections.Generic.ICollection`1[System.Nullable`1[int]]:this (FullOpts)
 ; ============================================================

5 (2.53 % of base) - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Keys():System.Collections.ICollection:this

 ; Assembly listing for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Keys():System.Collections.ICollection:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
 ; rbp based frame
 ; partially interruptible
 ; No PGO data
-; 0 inlinees with PGO data; 3 single block inlinees; 2 inlinees without PGO data
+; 0 inlinees with PGO data; 6 single block inlinees; 2 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T01] (  5,  5   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]>
+;  V00 this         [V00,T02] (  5,  5   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]>
 ;# V01 OutArgs      [V01    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
-;  V02 tmp1         [V02,T00] (  5, 10   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.KeysCollectionAccessor`2[System.__Canon,System.Nullable`1[int]]>
+;  V02 tmp1         [V02,T01] (  4,  8   )     ref  ->  r14         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.KeysCollectionAccessor`2[System.__Canon,System.Nullable`1[int]]>
 ;* V03 tmp2         [V03    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V04 tmp3         [V04,T02] (  4,  6   )    long  ->  r11         "spilling helperCall"
-;* V05 tmp4         [V05    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V06 tmp5         [V06,T03] (  3,  6   )     ref  ->  r14         class-hnd single-def "Inlining Arg" <System.Collections.Generic.IEnumerable`1[System.__Canon]>
+;* V04 tmp3         [V04    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V05 tmp4         [V05,T00] (  5, 10   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.ImmutableDictionary`2+<get_Keys>d__25[System.__Canon,System.Nullable`1[int]]>
+;* V06 tmp5         [V06    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
 ;* V07 tmp6         [V07    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V08 rat0         [V08,T06] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V09 rat1         [V09,T08] (  3,  4   )    long  ->  rsi         "runtime lookup"
-;  V10 rat2         [V10,T04] (  3,  5.60)    long  ->  rsi         "fgMakeTemp is creating a new local variable"
-;  V11 rat3         [V11,T07] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V12 rat4         [V12,T05] (  3,  5.60)    long  ->  r11         "fgMakeTemp is creating a new local variable"
+;* V08 tmp7         [V08    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V09 cse0         [V09,T07] (  5,  3.40)    long  ->  r15         "CSE #01: aggressive"
+;  V10 rat0         [V10,T05] (  3,  4   )    long  ->  rdi         "runtime lookup"
+;  V11 rat1         [V11,T03] (  3,  5.60)    long  ->  rdi         "fgMakeTemp is creating a new local variable"
+;  V12 rat2         [V12,T06] (  3,  4   )    long  ->  rdi         "runtime lookup"
+;  V13 rat3         [V13,T04] (  3,  5.60)    long  ->  rdi         "fgMakeTemp is creating a new local variable"
 ;
 ; Lcl frame size = 8
 
 G_M64668_IG01:
        push     rbp
        push     r15
        push     r14
        push     rbx
        push     rax
        lea      rbp, [rsp+0x20]
        mov      qword ptr [rbp-0x20], rdi
        mov      rbx, rdi
 						;; size=19 bbWeight=1 PerfScore 6.75
 G_M64668_IG02:
-       mov      rdi, qword ptr [rbx]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi]
-       mov      rsi, qword ptr [rsi+0x68]
-       test     rsi, rsi
+       mov      r15, qword ptr [rbx]
+       mov      rdi, qword ptr [r15+0x30]
+       mov      rdi, qword ptr [rdi]
+       mov      rdi, qword ptr [rdi+0x68]
+       test     rdi, rdi
        je       SHORT G_M64668_IG06
 						;; size=19 bbWeight=1 PerfScore 9.25
 G_M64668_IG03:
-       mov      rdi, rsi
+       call     CORINFO_HELP_NEWSFAST
+       mov      r14, rax
+       mov      rdi, qword ptr [r15+0x30]
+       mov      rdi, qword ptr [rdi]
+       mov      rdi, qword ptr [rdi+0x58]
+       test     rdi, rdi
+       je       SHORT G_M64668_IG07
+						;; size=24 bbWeight=1 PerfScore 8.50
+G_M64668_IG04:
        call     CORINFO_HELP_NEWSFAST
        mov      r15, rax
-       mov      rdi, qword ptr [r15]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi+0x08]
-       mov      r11, qword ptr [rsi+0x18]
-       test     r11, r11
-       je       SHORT G_M64668_IG07
-						;; size=31 bbWeight=1 PerfScore 10.75
-G_M64668_IG04:
-       mov      rdi, rbx
-       call     [r11]
-       mov      r14, rax
-       test     r14, r14
-       je       SHORT G_M64668_IG08
-       lea      rdi, bword ptr [r15+0x08]
+       mov      dword ptr [r15+0x18], -2
+       call     System.Environment:get_CurrentManagedThreadId():int
+       mov      dword ptr [r15+0x1C], eax
+       lea      rdi, bword ptr [r15+0x10]
        mov      rsi, rbx
        call     CORINFO_HELP_ASSIGN_REF
-       lea      rdi, bword ptr [r15+0x10]
-       mov      rsi, r14
+       lea      rdi, bword ptr [r14+0x08]
+       mov      rsi, rbx
        call     CORINFO_HELP_ASSIGN_REF
-       mov      rax, r15
-						;; size=41 bbWeight=1 PerfScore 8.50
+       lea      rdi, bword ptr [r14+0x10]
+       mov      rsi, r15
+       call     CORINFO_HELP_ASSIGN_REF
+       mov      rax, r14
+						;; size=64 bbWeight=1 PerfScore 9.75
 G_M64668_IG05:
        add      rsp, 8
        pop      rbx
        pop      r14
        pop      r15
        pop      rbp
        ret      
 						;; size=11 bbWeight=1 PerfScore 3.25
 G_M64668_IG06:
+       mov      rdi, r15
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      rsi, rax
-       jmp      SHORT G_M64668_IG03
-						;; size=27 bbWeight=0.20 PerfScore 1.15
+       mov      rdi, rax
+       jmp      G_M64668_IG03
+						;; size=33 bbWeight=0.20 PerfScore 1.20
 G_M64668_IG07:
+       mov      rdi, r15
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r11, rax
-       jmp      SHORT G_M64668_IG04
-						;; size=27 bbWeight=0.20 PerfScore 1.15
-G_M64668_IG08:
-       mov      rdi, 0xD1FFAB1E      ; 'keysOrValues'
-       mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.Requires:FailArgumentNullException(System.String)
-       call     [rax]System.Collections.Immutable.Requires:FailArgumentNullException(System.String)
-       int3     
-						;; size=23 bbWeight=0 PerfScore 0.00
+       mov      rdi, rax
+       jmp      G_M64668_IG04
+						;; size=33 bbWeight=0.20 PerfScore 1.20
 
-; Total bytes of code 198, prolog size 16, PerfScore 40.80, instruction count 55, allocated bytes for code 198 (MethodHash=ddfd0363) for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Keys():System.Collections.ICollection:this (FullOpts)
+; Total bytes of code 203, prolog size 16, PerfScore 39.90, instruction count 54, allocated bytes for code 203 (MethodHash=ddfd0363) for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Keys():System.Collections.ICollection:this (FullOpts)
 ; ============================================================

5 (2.53 % of base) - System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Values():System.Collections.ICollection:this

 ; Assembly listing for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Values():System.Collections.ICollection:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
 ; rbp based frame
 ; partially interruptible
 ; No PGO data
-; 0 inlinees with PGO data; 3 single block inlinees; 2 inlinees without PGO data
+; 0 inlinees with PGO data; 6 single block inlinees; 2 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T01] (  5,  5   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]>
+;  V00 this         [V00,T02] (  5,  5   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]>
 ;# V01 OutArgs      [V01    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
-;  V02 tmp1         [V02,T00] (  5, 10   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.ValuesCollectionAccessor`2[System.__Canon,System.Nullable`1[int]]>
+;  V02 tmp1         [V02,T01] (  4,  8   )     ref  ->  r14         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.ValuesCollectionAccessor`2[System.__Canon,System.Nullable`1[int]]>
 ;* V03 tmp2         [V03    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V04 tmp3         [V04,T02] (  4,  6   )    long  ->  r11         "spilling helperCall"
-;* V05 tmp4         [V05    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V06 tmp5         [V06,T03] (  3,  6   )     ref  ->  r14         class-hnd single-def "Inlining Arg" <System.Collections.Generic.IEnumerable`1[System.Nullable`1[int]]>
-;  V07 rat0         [V07,T06] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V08 rat1         [V08,T08] (  3,  4   )    long  ->  rsi         "runtime lookup"
-;  V09 rat2         [V09,T04] (  3,  5.60)    long  ->  rsi         "fgMakeTemp is creating a new local variable"
-;  V10 rat3         [V10,T07] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V11 rat4         [V11,T05] (  3,  5.60)    long  ->  r11         "fgMakeTemp is creating a new local variable"
+;* V04 tmp3         [V04    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V05 tmp4         [V05,T00] (  5, 10   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.Collections.Immutable.ImmutableDictionary`2+<get_Values>d__27[System.__Canon,System.Nullable`1[int]]>
+;* V06 tmp5         [V06    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V07 tmp6         [V07    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V08 cse0         [V08,T07] (  5,  3.40)    long  ->  r15         "CSE #01: aggressive"
+;  V09 rat0         [V09,T05] (  3,  4   )    long  ->  rdi         "runtime lookup"
+;  V10 rat1         [V10,T03] (  3,  5.60)    long  ->  rdi         "fgMakeTemp is creating a new local variable"
+;  V11 rat2         [V11,T06] (  3,  4   )    long  ->  rdi         "runtime lookup"
+;  V12 rat3         [V12,T04] (  3,  5.60)    long  ->  rdi         "fgMakeTemp is creating a new local variable"
 ;
 ; Lcl frame size = 8
 
 G_M18592_IG01:
        push     rbp
        push     r15
        push     r14
        push     rbx
        push     rax
        lea      rbp, [rsp+0x20]
        mov      qword ptr [rbp-0x20], rdi
        mov      rbx, rdi
 						;; size=19 bbWeight=1 PerfScore 6.75
 G_M18592_IG02:
-       mov      rdi, qword ptr [rbx]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi]
-       mov      rsi, qword ptr [rsi+0x70]
-       test     rsi, rsi
+       mov      r15, qword ptr [rbx]
+       mov      rdi, qword ptr [r15+0x30]
+       mov      rdi, qword ptr [rdi]
+       mov      rdi, qword ptr [rdi+0x70]
+       test     rdi, rdi
        je       SHORT G_M18592_IG06
 						;; size=19 bbWeight=1 PerfScore 9.25
 G_M18592_IG03:
-       mov      rdi, rsi
+       call     CORINFO_HELP_NEWSFAST
+       mov      r14, rax
+       mov      rdi, qword ptr [r15+0x30]
+       mov      rdi, qword ptr [rdi]
+       mov      rdi, qword ptr [rdi+0x60]
+       test     rdi, rdi
+       je       SHORT G_M18592_IG07
+						;; size=24 bbWeight=1 PerfScore 8.50
+G_M18592_IG04:
        call     CORINFO_HELP_NEWSFAST
        mov      r15, rax
-       mov      rdi, qword ptr [r15]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi+0x08]
-       mov      r11, qword ptr [rsi+0x18]
-       test     r11, r11
-       je       SHORT G_M18592_IG07
-						;; size=31 bbWeight=1 PerfScore 10.75
-G_M18592_IG04:
-       mov      rdi, rbx
-       call     [r11]
-       mov      r14, rax
-       test     r14, r14
-       je       SHORT G_M18592_IG08
+       mov      dword ptr [r15+0x10], -2
+       call     System.Environment:get_CurrentManagedThreadId():int
+       mov      dword ptr [r15+0x14], eax
        lea      rdi, bword ptr [r15+0x08]
        mov      rsi, rbx
        call     CORINFO_HELP_ASSIGN_REF
-       lea      rdi, bword ptr [r15+0x10]
-       mov      rsi, r14
+       lea      rdi, bword ptr [r14+0x08]
+       mov      rsi, rbx
        call     CORINFO_HELP_ASSIGN_REF
-       mov      rax, r15
-						;; size=41 bbWeight=1 PerfScore 8.50
+       lea      rdi, bword ptr [r14+0x10]
+       mov      rsi, r15
+       call     CORINFO_HELP_ASSIGN_REF
+       mov      rax, r14
+						;; size=64 bbWeight=1 PerfScore 9.75
 G_M18592_IG05:
        add      rsp, 8
        pop      rbx
        pop      r14
        pop      r15
        pop      rbp
        ret      
 						;; size=11 bbWeight=1 PerfScore 3.25
 G_M18592_IG06:
+       mov      rdi, r15
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      rsi, rax
-       jmp      SHORT G_M18592_IG03
-						;; size=27 bbWeight=0.20 PerfScore 1.15
+       mov      rdi, rax
+       jmp      G_M18592_IG03
+						;; size=33 bbWeight=0.20 PerfScore 1.20
 G_M18592_IG07:
+       mov      rdi, r15
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r11, rax
-       jmp      SHORT G_M18592_IG04
-						;; size=27 bbWeight=0.20 PerfScore 1.15
-G_M18592_IG08:
-       mov      rdi, 0xD1FFAB1E      ; 'keysOrValues'
-       mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.Requires:FailArgumentNullException(System.String)
-       call     [rax]System.Collections.Immutable.Requires:FailArgumentNullException(System.String)
-       int3     
-						;; size=23 bbWeight=0 PerfScore 0.00
+       mov      rdi, rax
+       jmp      G_M18592_IG04
+						;; size=33 bbWeight=0.20 PerfScore 1.20
 
-; Total bytes of code 198, prolog size 16, PerfScore 40.80, instruction count 55, allocated bytes for code 198 (MethodHash=1534b75f) for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Values():System.Collections.ICollection:this (FullOpts)
+; Total bytes of code 203, prolog size 16, PerfScore 39.90, instruction count 54, allocated bytes for code 203 (MethodHash=1534b75f) for method System.Collections.Immutable.ImmutableDictionary`2[System.__Canon,System.Nullable`1[int]]:System.Collections.IDictionary.get_Values():System.Collections.ICollection:this (FullOpts)
 ; ============================================================

[MihuBot]

Top method improvements

-191 (-52.91 % of base) - System.Collections.Immutable.ImmutableList`1[System.__Canon]:Replace(System.__Canon,System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this

 ; Assembly listing for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:Replace(System.__Canon,System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
 ; rbp based frame
 ; partially interruptible
 ; No PGO data
-; 0 inlinees with PGO data; 2 single block inlinees; 1 inlinees without PGO data
+; 0 inlinees with PGO data; 5 single block inlinees; 1 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T00] (  7,  7   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
-;  V01 arg1         [V01,T07] (  3,  3   )     ref  ->  r15         class-hnd single-def <System.__Canon>
-;  V02 arg2         [V02,T08] (  3,  3   )     ref  ->  r14         class-hnd single-def <System.__Canon>
-;  V03 arg3         [V03,T09] (  3,  3   )     ref  ->  r13         class-hnd single-def <System.Collections.Generic.IEqualityComparer`1[System.__Canon]>
-;  V04 loc0         [V04,T13] (  3,  3   )     int  ->  rax        
+;  V00 this         [V00,T00] (  6,  6   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
+;  V01 arg1         [V01,T01] (  3,  3   )     ref  ->  rsi         class-hnd single-def <System.__Canon>
+;  V02 arg2         [V02,T02] (  3,  3   )     ref  ->  r15         class-hnd single-def <System.__Canon>
+;  V03 arg3         [V03,T03] (  3,  3   )     ref  ->   r8         class-hnd single-def <System.Collections.Generic.IEqualityComparer`1[System.__Canon]>
+;  V04 loc0         [V04,T06] (  3,  3   )     int  ->  rax        
 ;# V05 OutArgs      [V05    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
 ;* V06 tmp1         [V06    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V07 tmp2         [V07,T14] (  3,  0   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.ArgumentException>
-;  V08 tmp3         [V08,T01] (  6,  6.80)    long  ->  r12         "Inlining Arg"
+;  V07 tmp2         [V07,T07] (  3,  0   )     ref  ->  r15         class-hnd exact single-def "NewObj constructor temp" <System.ArgumentException>
+;* V08 tmp3         [V08    ] (  0,  0   )    long  ->  zero-ref    "Inlining Arg"
 ;* V09 tmp4         [V09    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V10 tmp5         [V10,T02] (  4,  6   )    long  ->  [rbp-0x38]  "spilling helperCall"
-;  V11 tmp6         [V11,T03] (  4,  6   )    long  ->  r12         "spilling helperCall"
-;  V12 tmp7         [V12,T12] (  2,  4   )     int  ->  rcx         "argument with side effect"
-;  V13 tmp8         [V13,T11] (  2,  4   )     ref  ->  rsi         single-def "argument with side effect"
-;  V14 tmp9         [V14,T15] (  2,  0   )     ref  ->  rsi         single-def "argument with side effect"
-;  V15 rat0         [V15,T10] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V16 rat1         [V16,T04] (  3,  5.60)    long  ->  r12         "fgMakeTemp is creating a new local variable"
-;  V17 rat2         [V17,T05] (  3,  5.60)    long  ->  rax         "fgMakeTemp is creating a new local variable"
-;  V18 rat3         [V18,T06] (  3,  5.60)    long  ->  rcx         "fgMakeTemp is creating a new local variable"
+;* V10 tmp5         [V10    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V11 tmp6         [V11    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V12 tmp7         [V12    ] (  0,  0   )     ref  ->  zero-ref    class-hnd exact "Inlining Arg" <System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]>
+;* V13 tmp8         [V13    ] (  0,  0   )     int  ->  zero-ref    "Inlining Arg"
+;  V14 tmp9         [V14,T04] (  2,  4   )     ref  ->  rsi         single-def "argument with side effect"
+;  V15 tmp10        [V15,T08] (  2,  0   )     ref  ->  rsi         single-def "argument with side effect"
+;  V16 cse0         [V16,T05] (  3,  3   )     ref  ->  rdi         "CSE #01: aggressive"
 ;
-; Lcl frame size = 24
+; Lcl frame size = 16
 
 G_M52305_IG01:
        push     rbp
        push     r15
-       push     r14
-       push     r13
-       push     r12
        push     rbx
-       sub      rsp, 24
-       lea      rbp, [rsp+0x40]
-       mov      qword ptr [rbp-0x30], rdi
+       sub      rsp, 16
+       lea      rbp, [rsp+0x20]
+       mov      qword ptr [rbp-0x18], rdi
        mov      rbx, rdi
-       mov      r15, rsi
-       mov      r14, rdx
-       mov      r13, rcx
-						;; size=35 bbWeight=1 PerfScore 8.75
+       mov      r15, rdx
+       mov      r8, rcx
+						;; size=26 bbWeight=1 PerfScore 5.50
 G_M52305_IG02:
-       mov      rdi, qword ptr [rbx]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi]
-       mov      r12, qword ptr [rsi+0x40]
-       test     r12, r12
-       je       G_M52305_IG08
-						;; size=23 bbWeight=1 PerfScore 9.25
-G_M52305_IG03:
-       mov      rdi, qword ptr [r12+0x18]
-       mov      rax, qword ptr [rdi+0x18]
-       test     rax, rax
-       je       G_M52305_IG09
-						;; size=18 bbWeight=1 PerfScore 5.25
-G_M52305_IG04:
-       mov      rdi, qword ptr [r12+0x18]
-       mov      rcx, qword ptr [rdi+0x20]
-       test     rcx, rcx
-       je       G_M52305_IG10
-						;; size=18 bbWeight=1 PerfScore 5.25
-G_M52305_IG05:
-       mov      r12, rcx
-						;; size=3 bbWeight=0.80 PerfScore 0.20
-G_M52305_IG06:
-       mov      rdi, rbx
-       mov      r11, rax
-       call     [rax]
-       mov      ecx, eax
-       mov      r11, r12
-       mov      rsi, r15
-       mov      r8, r13
-       mov      rdi, rbx
+       cmp      dword ptr [rbx], ebx
+       mov      rdi, gword ptr [rbx+0x08]
+       mov      ecx, dword ptr [rdi+0x20]
        xor      edx, edx
-       call     [r12]
+       mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
+       call     [rax]System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
        test     eax, eax
-       jl       G_M52305_IG11
+       jl       SHORT G_M52305_IG04
        mov      rdi, gword ptr [rbx+0x08]
        mov      esi, eax
-       mov      rdx, r14
+       mov      rdx, r15
        mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:ReplaceAt(int,System.__Canon):System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:this
        cmp      dword ptr [rdi], edi
        call     [rax]System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:ReplaceAt(int,System.__Canon):System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:this
        mov      rsi, rax
        mov      rdi, rbx
        mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1[System.__Canon]:Wrap(System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this
-						;; size=75 bbWeight=1 PerfScore 18.75
-G_M52305_IG07:
-       add      rsp, 24
+						;; size=66 bbWeight=1 PerfScore 21.25
+G_M52305_IG03:
+       add      rsp, 16
        pop      rbx
-       pop      r12
-       pop      r13
-       pop      r14
        pop      r15
        pop      rbp
        tail.jmp [rax]System.Collections.Immutable.ImmutableList`1[System.__Canon]:Wrap(System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this
-						;; size=17 bbWeight=1 PerfScore 7.25
-G_M52305_IG08:
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r12, rax
-       jmp      G_M52305_IG03
-						;; size=30 bbWeight=0.20 PerfScore 1.15
-G_M52305_IG09:
-       mov      rdi, r12
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      qword ptr [rbp-0x38], rax
-       jmp      G_M52305_IG04
-						;; size=34 bbWeight=0.20 PerfScore 1.35
-G_M52305_IG10:
-       mov      qword ptr [rbp-0x38], rax
-       mov      rdi, r12
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rcx, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rcx]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      r12, rax
-       mov      rax, qword ptr [rbp-0x38]
-       jmp      G_M52305_IG06
-						;; size=41 bbWeight=0.20 PerfScore 1.60
-G_M52305_IG11:
+						;; size=11 bbWeight=1 PerfScore 5.75
+G_M52305_IG04:
        mov      rdi, 0xD1FFAB1E      ; System.ArgumentException
        call     CORINFO_HELP_NEWSFAST
        mov      r15, rax
        mov      rax, 0xD1FFAB1E      ; code for System.SR:get_CannotFindOldValue():System.String
        call     [rax]System.SR:get_CannotFindOldValue():System.String
        mov      rsi, rax
        mov      rdi, r15
        mov      rdx, 0xD1FFAB1E      ; 'oldValue'
        mov      rax, 0xD1FFAB1E      ; code for System.ArgumentException:.ctor(System.String,System.String):this
        call     [rax]System.ArgumentException:.ctor(System.String,System.String):this
        mov      rdi, r15
        call     CORINFO_HELP_THROW
        int3     
 						;; size=67 bbWeight=0 PerfScore 0.00
 
-; Total bytes of code 361, prolog size 23, PerfScore 58.80, instruction count 89, allocated bytes for code 361 (MethodHash=312b33ae) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:Replace(System.__Canon,System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
+; Total bytes of code 170, prolog size 17, PerfScore 32.50, instruction count 44, allocated bytes for code 170 (MethodHash=312b33ae) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:Replace(System.__Canon,System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
 ; ============================================================

-190 (-71.70 % of base) - System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this

 ; Assembly listing for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
-; rbp based frame
+; rsp based frame
 ; partially interruptible
 ; No PGO data
-; 0 inlinees with PGO data; 1 single block inlinees; 1 inlinees without PGO data
+; 0 inlinees with PGO data; 4 single block inlinees; 1 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T00] (  7,  6   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
-;  V01 arg1         [V01,T07] (  3,  3   )     ref  ->  r15         class-hnd single-def <System.__Canon>
-;  V02 arg2         [V02,T08] (  3,  3   )     ref  ->  r14         class-hnd single-def <System.Collections.Generic.IEqualityComparer`1[System.__Canon]>
-;  V03 loc0         [V03,T11] (  3,  2.50)     int  ->  rsi        
+;  V00 this         [V00,T00] (  6,  5   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
+;  V01 arg1         [V01,T01] (  3,  3   )     ref  ->  rsi         class-hnd single-def <System.__Canon>
+;  V02 arg2         [V02,T02] (  3,  3   )     ref  ->  rdx         class-hnd single-def <System.Collections.Generic.IEqualityComparer`1[System.__Canon]>
+;  V03 loc0         [V03,T04] (  3,  2.50)     int  ->  rsi        
 ;# V04 OutArgs      [V04    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
 ;* V05 tmp1         [V05    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V06 tmp2         [V06,T01] (  6,  6.80)    long  ->  r13         "Inlining Arg"
+;* V06 tmp2         [V06    ] (  0,  0   )    long  ->  zero-ref    "Inlining Arg"
 ;* V07 tmp3         [V07    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V08 tmp4         [V08,T02] (  4,  6   )    long  ->  r12         "spilling helperCall"
-;  V09 tmp5         [V09,T03] (  4,  6   )    long  ->  r13         "spilling helperCall"
-;  V10 tmp6         [V10,T10] (  2,  4   )     int  ->  rcx         "argument with side effect"
-;  V11 rat0         [V11,T09] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V12 rat1         [V12,T04] (  3,  5.60)    long  ->  r13         "fgMakeTemp is creating a new local variable"
-;  V13 rat2         [V13,T05] (  3,  5.60)    long  ->  r12         "fgMakeTemp is creating a new local variable"
-;  V14 rat3         [V14,T06] (  3,  5.60)    long  ->  rax         "fgMakeTemp is creating a new local variable"
+;* V08 tmp4         [V08    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V09 tmp5         [V09    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V10 tmp6         [V10    ] (  0,  0   )     ref  ->  zero-ref    class-hnd exact "Inlining Arg" <System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]>
+;* V11 tmp7         [V11    ] (  0,  0   )     int  ->  zero-ref    "Inlining Arg"
+;  V12 cse0         [V12,T03] (  3,  3   )     ref  ->  rdi         "CSE #01: aggressive"
 ;
-; Lcl frame size = 8
+; Lcl frame size = 16
 
 G_M34865_IG01:
-       push     rbp
-       push     r15
-       push     r14
-       push     r13
-       push     r12
        push     rbx
-       push     rax
-       lea      rbp, [rsp+0x30]
-       mov      qword ptr [rbp-0x30], rdi
+       sub      rsp, 16
+       mov      qword ptr [rsp+0x08], rdi
        mov      rbx, rdi
-       mov      r15, rsi
-       mov      r14, rdx
-						;; size=29 bbWeight=1 PerfScore 9.25
+						;; size=13 bbWeight=1 PerfScore 2.50
 G_M34865_IG02:
-       mov      rdi, qword ptr [rbx]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi]
-       mov      r13, qword ptr [rsi+0x40]
-       test     r13, r13
-       je       SHORT G_M34865_IG09
-						;; size=19 bbWeight=1 PerfScore 9.25
-G_M34865_IG03:
-       mov      rdi, qword ptr [r13+0x18]
-       mov      r12, qword ptr [rdi+0x18]
-       test     r12, r12
-       je       SHORT G_M34865_IG10
-						;; size=13 bbWeight=1 PerfScore 5.25
-G_M34865_IG04:
-       mov      rdi, qword ptr [r13+0x18]
-       mov      rax, qword ptr [rdi+0x20]
-       test     rax, rax
-       je       G_M34865_IG11
-						;; size=17 bbWeight=1 PerfScore 5.25
-G_M34865_IG05:
-       mov      r13, rax
-						;; size=3 bbWeight=0.80 PerfScore 0.20
-G_M34865_IG06:
-       mov      rdi, rbx
-       mov      r11, r12
-       call     [r12]
-       mov      ecx, eax
-       mov      r11, r13
-       mov      rsi, r15
-       mov      r8, r14
-       mov      rdi, rbx
+       cmp      dword ptr [rbx], ebx
+       mov      rdi, gword ptr [rbx+0x08]
+       mov      ecx, dword ptr [rdi+0x20]
+       mov      r8, rdx
        xor      edx, edx
-       call     [r13]
+       mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
+       call     [rax]System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
        mov      esi, eax
        test     esi, esi
-       jl       G_M34865_IG12
-						;; size=40 bbWeight=1 PerfScore 9.50
-G_M34865_IG07:
+       jge      SHORT G_M34865_IG05
+						;; size=32 bbWeight=1 PerfScore 12.25
+G_M34865_IG03:
+       mov      rax, rbx
+						;; size=3 bbWeight=0.50 PerfScore 0.12
+G_M34865_IG04:
+       add      rsp, 16
+       pop      rbx
+       ret      
+						;; size=6 bbWeight=0.50 PerfScore 0.88
+G_M34865_IG05:
        mov      rdi, rbx
        mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1[System.__Canon]:RemoveAt(int):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this
 						;; size=13 bbWeight=0.50 PerfScore 0.25
-G_M34865_IG08:
-       add      rsp, 8
+G_M34865_IG06:
+       add      rsp, 16
        pop      rbx
-       pop      r12
-       pop      r13
-       pop      r14
-       pop      r15
-       pop      rbp
        tail.jmp [rax]System.Collections.Immutable.ImmutableList`1[System.__Canon]:RemoveAt(int):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this
-						;; size=17 bbWeight=0.50 PerfScore 3.62
-G_M34865_IG09:
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r13, rax
-       jmp      G_M34865_IG03
-						;; size=30 bbWeight=0.20 PerfScore 1.15
-G_M34865_IG10:
-       mov      rdi, r13
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      r12, rax
-       jmp      G_M34865_IG04
-						;; size=33 bbWeight=0.20 PerfScore 1.20
-G_M34865_IG11:
-       mov      rdi, r13
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      r13, rax
-       jmp      G_M34865_IG06
-						;; size=33 bbWeight=0.20 PerfScore 1.20
-G_M34865_IG12:
-       mov      rax, rbx
-						;; size=3 bbWeight=0.50 PerfScore 0.12
-G_M34865_IG13:
-       add      rsp, 8
-       pop      rbx
-       pop      r12
-       pop      r13
-       pop      r14
-       pop      r15
-       pop      rbp
-       ret      
-						;; size=15 bbWeight=0.50 PerfScore 2.12
+						;; size=8 bbWeight=0.50 PerfScore 2.38
 
-; Total bytes of code 265, prolog size 20, PerfScore 48.37, instruction count 76, allocated bytes for code 265 (MethodHash=0f4d77ce) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
+; Total bytes of code 75, prolog size 10, PerfScore 18.38, instruction count 23, allocated bytes for code 75 (MethodHash=0f4d77ce) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
 ; ============================================================

-190 (-71.70 % of base) - System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.Immutable.IImmutableList.Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.IImmutableList`1[System.__Canon]:this

 ; Assembly listing for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.Immutable.IImmutableList<T>.Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.IImmutableList`1[System.__Canon]:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
-; rbp based frame
+; rsp based frame
 ; partially interruptible
 ; No PGO data
-; 0 inlinees with PGO data; 1 single block inlinees; 2 inlinees without PGO data
+; 0 inlinees with PGO data; 4 single block inlinees; 2 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T00] (  7,  6   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
-;  V01 arg1         [V01,T07] (  3,  3   )     ref  ->  r15         class-hnd single-def <System.__Canon>
-;  V02 arg2         [V02,T08] (  3,  3   )     ref  ->  r14         class-hnd single-def <System.Collections.Generic.IEqualityComparer`1[System.__Canon]>
+;  V00 this         [V00,T00] (  6,  5   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
+;  V01 arg1         [V01,T01] (  3,  3   )     ref  ->  rsi         class-hnd single-def <System.__Canon>
+;  V02 arg2         [V02,T02] (  3,  3   )     ref  ->  rdx         class-hnd single-def <System.Collections.Generic.IEqualityComparer`1[System.__Canon]>
 ;# V03 OutArgs      [V03    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
 ;* V04 tmp1         [V04    ] (  0,  0   )     ref  ->  zero-ref    class-hnd exact single-def "Inline return value spill temp" <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
 ;* V05 tmp2         [V05    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V06 tmp3         [V06,T11] (  3,  2.50)     int  ->  rsi         "Inline stloc first use temp"
-;  V07 tmp4         [V07,T01] (  6,  6.80)    long  ->  r13         "Inlining Arg"
+;  V06 tmp3         [V06,T04] (  3,  2.50)     int  ->  rsi         "Inline stloc first use temp"
+;* V07 tmp4         [V07    ] (  0,  0   )    long  ->  zero-ref    "Inlining Arg"
 ;* V08 tmp5         [V08    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V09 tmp6         [V09,T02] (  4,  6   )    long  ->  r12         "spilling helperCall"
-;  V10 tmp7         [V10,T03] (  4,  6   )    long  ->  r13         "spilling helperCall"
-;  V11 tmp8         [V11,T10] (  2,  4   )     int  ->  rcx         "argument with side effect"
-;  V12 rat0         [V12,T09] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V13 rat1         [V13,T04] (  3,  5.60)    long  ->  r13         "fgMakeTemp is creating a new local variable"
-;  V14 rat2         [V14,T05] (  3,  5.60)    long  ->  r12         "fgMakeTemp is creating a new local variable"
-;  V15 rat3         [V15,T06] (  3,  5.60)    long  ->  rax         "fgMakeTemp is creating a new local variable"
+;* V09 tmp6         [V09    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V10 tmp7         [V10    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V11 tmp8         [V11    ] (  0,  0   )     ref  ->  zero-ref    class-hnd exact "Inlining Arg" <System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]>
+;* V12 tmp9         [V12    ] (  0,  0   )     int  ->  zero-ref    "Inlining Arg"
+;  V13 cse0         [V13,T03] (  3,  3   )     ref  ->  rdi         "CSE #01: aggressive"
 ;
-; Lcl frame size = 8
+; Lcl frame size = 16
 
 G_M50437_IG01:
-       push     rbp
-       push     r15
-       push     r14
-       push     r13
-       push     r12
        push     rbx
-       push     rax
-       lea      rbp, [rsp+0x30]
-       mov      qword ptr [rbp-0x30], rdi
+       sub      rsp, 16
+       mov      qword ptr [rsp+0x08], rdi
        mov      rbx, rdi
-       mov      r15, rsi
-       mov      r14, rdx
-						;; size=29 bbWeight=1 PerfScore 9.25
+						;; size=13 bbWeight=1 PerfScore 2.50
 G_M50437_IG02:
-       mov      rdi, qword ptr [rbx]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi]
-       mov      r13, qword ptr [rsi+0x40]
-       test     r13, r13
-       je       SHORT G_M50437_IG09
-						;; size=19 bbWeight=1 PerfScore 9.25
-G_M50437_IG03:
-       mov      rdi, qword ptr [r13+0x18]
-       mov      r12, qword ptr [rdi+0x18]
-       test     r12, r12
-       je       SHORT G_M50437_IG10
-						;; size=13 bbWeight=1 PerfScore 5.25
-G_M50437_IG04:
-       mov      rdi, qword ptr [r13+0x18]
-       mov      rax, qword ptr [rdi+0x20]
-       test     rax, rax
-       je       G_M50437_IG11
-						;; size=17 bbWeight=1 PerfScore 5.25
-G_M50437_IG05:
-       mov      r13, rax
-						;; size=3 bbWeight=0.80 PerfScore 0.20
-G_M50437_IG06:
-       mov      rdi, rbx
-       mov      r11, r12
-       call     [r12]
-       mov      ecx, eax
-       mov      r11, r13
-       mov      rsi, r15
-       mov      r8, r14
-       mov      rdi, rbx
+       cmp      dword ptr [rbx], ebx
+       mov      rdi, gword ptr [rbx+0x08]
+       mov      ecx, dword ptr [rdi+0x20]
+       mov      r8, rdx
        xor      edx, edx
-       call     [r13]
+       mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
+       call     [rax]System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
        mov      esi, eax
        test     esi, esi
-       jl       G_M50437_IG12
-						;; size=40 bbWeight=1 PerfScore 9.50
-G_M50437_IG07:
+       jge      SHORT G_M50437_IG05
+						;; size=32 bbWeight=1 PerfScore 12.25
+G_M50437_IG03:
+       mov      rax, rbx
+						;; size=3 bbWeight=0.50 PerfScore 0.12
+G_M50437_IG04:
+       add      rsp, 16
+       pop      rbx
+       ret      
+						;; size=6 bbWeight=0.50 PerfScore 0.88
+G_M50437_IG05:
        mov      rdi, rbx
        mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1[System.__Canon]:RemoveAt(int):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this
 						;; size=13 bbWeight=0.50 PerfScore 0.25
-G_M50437_IG08:
-       add      rsp, 8
+G_M50437_IG06:
+       add      rsp, 16
        pop      rbx
-       pop      r12
-       pop      r13
-       pop      r14
-       pop      r15
-       pop      rbp
        tail.jmp [rax]System.Collections.Immutable.ImmutableList`1[System.__Canon]:RemoveAt(int):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this
-						;; size=17 bbWeight=0.50 PerfScore 3.62
-G_M50437_IG09:
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r13, rax
-       jmp      G_M50437_IG03
-						;; size=30 bbWeight=0.20 PerfScore 1.15
-G_M50437_IG10:
-       mov      rdi, r13
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      r12, rax
-       jmp      G_M50437_IG04
-						;; size=33 bbWeight=0.20 PerfScore 1.20
-G_M50437_IG11:
-       mov      rdi, r13
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      r13, rax
-       jmp      G_M50437_IG06
-						;; size=33 bbWeight=0.20 PerfScore 1.20
-G_M50437_IG12:
-       mov      rax, rbx
-						;; size=3 bbWeight=0.50 PerfScore 0.12
-G_M50437_IG13:
-       add      rsp, 8
-       pop      rbx
-       pop      r12
-       pop      r13
-       pop      r14
-       pop      r15
-       pop      rbp
-       ret      
-						;; size=15 bbWeight=0.50 PerfScore 2.12
+						;; size=8 bbWeight=0.50 PerfScore 2.38
 
-; Total bytes of code 265, prolog size 20, PerfScore 48.37, instruction count 76, allocated bytes for code 265 (MethodHash=05023afa) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.Immutable.IImmutableList<T>.Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.IImmutableList`1[System.__Canon]:this (FullOpts)
+; Total bytes of code 75, prolog size 10, PerfScore 18.38, instruction count 23, allocated bytes for code 75 (MethodHash=05023afa) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.Immutable.IImmutableList<T>.Remove(System.__Canon,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):System.Collections.Immutable.IImmutableList`1[System.__Canon]:this (FullOpts)
 ; ============================================================

-188 (-55.13 % of base) - System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this

 ; Assembly listing for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
 ; rbp based frame
 ; partially interruptible
 ; No PGO data
-; 0 inlinees with PGO data; 2 single block inlinees; 2 inlinees without PGO data
+; 0 inlinees with PGO data; 5 single block inlinees; 2 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T00] (  8,  7   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
-;  V01 arg1         [V01,T08] (  3,  3   )     ref  ->  r15         class-hnd single-def <System.__Canon>
+;  V00 this         [V00,T00] (  6,  5   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
+;  V01 arg1         [V01,T02] (  3,  3   )     ref  ->  r15         class-hnd single-def <System.__Canon>
 ;# V02 OutArgs      [V02    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
 ;* V03 tmp1         [V03    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
 ;* V04 tmp2         [V04    ] (  0,  0   )    long  ->  zero-ref    "Inlining Arg"
 ;* V05 tmp3         [V05    ] (  0,  0   )     ref  ->  zero-ref    class-hnd exact single-def "Inline return value spill temp" <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
-;  V06 tmp4         [V06,T12] (  2,  4   )     ref  ->  r14         class-hnd single-def "Inlining Arg" <System.Collections.Generic.EqualityComparer`1[System.__Canon]>
+;  V06 tmp4         [V06,T05] (  2,  4   )     ref  ->   r8         class-hnd single-def "Inlining Arg" <System.Collections.Generic.EqualityComparer`1[System.__Canon]>
 ;* V07 tmp5         [V07    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V08 tmp6         [V08,T14] (  3,  2.50)     int  ->  rsi         "Inline stloc first use temp"
-;  V09 tmp7         [V09,T01] (  6,  6.80)    long  ->  r13         "Inlining Arg"
+;  V08 tmp6         [V08,T07] (  3,  2.50)     int  ->  rsi         "Inline stloc first use temp"
+;* V09 tmp7         [V09    ] (  0,  0   )    long  ->  zero-ref    "Inlining Arg"
 ;* V10 tmp8         [V10    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V11 tmp9         [V11,T02] (  4,  6   )    long  ->  r12         "spilling helperCall"
-;  V12 tmp10        [V12,T03] (  4,  6   )    long  ->  r13         "spilling helperCall"
-;  V13 tmp11        [V13,T13] (  2,  4   )     int  ->  rcx         "argument with side effect"
-;  V14 rat0         [V14,T09] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V15 rat1         [V15,T11] (  3,  4   )    long  ->  rsi         "runtime lookup"
-;  V16 rat2         [V16,T04] (  3,  5.60)    long  ->  rsi         "fgMakeTemp is creating a new local variable"
-;  V17 rat3         [V17,T10] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V18 rat4         [V18,T05] (  3,  5.60)    long  ->  r13         "fgMakeTemp is creating a new local variable"
-;  V19 rat5         [V19,T06] (  3,  5.60)    long  ->  r12         "fgMakeTemp is creating a new local variable"
-;  V20 rat6         [V20,T07] (  3,  5.60)    long  ->  rax         "fgMakeTemp is creating a new local variable"
+;* V11 tmp9         [V11    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V12 tmp10        [V12    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V13 tmp11        [V13    ] (  0,  0   )     ref  ->  zero-ref    class-hnd exact "Inlining Arg" <System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]>
+;* V14 tmp12        [V14    ] (  0,  0   )     int  ->  zero-ref    "Inlining Arg"
+;  V15 cse0         [V15,T06] (  3,  3   )     ref  ->  rdi         "CSE #01: aggressive"
+;  V16 rat0         [V16,T03] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
+;  V17 rat1         [V17,T04] (  3,  4   )    long  ->  rsi         "runtime lookup"
+;  V18 rat2         [V18,T01] (  3,  5.60)    long  ->  rsi         "fgMakeTemp is creating a new local variable"
 ;
-; Lcl frame size = 8
+; Lcl frame size = 16
 
 G_M8455_IG01:
        push     rbp
        push     r15
-       push     r14
-       push     r13
-       push     r12
        push     rbx
-       push     rax
-       lea      rbp, [rsp+0x30]
-       mov      qword ptr [rbp-0x30], rdi
+       sub      rsp, 16
+       lea      rbp, [rsp+0x20]
+       mov      qword ptr [rbp-0x18], rdi
        mov      rbx, rdi
        mov      r15, rsi
-						;; size=26 bbWeight=1 PerfScore 9.00
+						;; size=23 bbWeight=1 PerfScore 5.25
 G_M8455_IG02:
        mov      rdi, qword ptr [rbx]
        mov      rsi, qword ptr [rdi+0x30]
        mov      rsi, qword ptr [rsi]
        mov      rsi, qword ptr [rsi+0x38]
        test     rsi, rsi
-       je       G_M8455_IG10
-						;; size=23 bbWeight=1 PerfScore 9.25
+       je       SHORT G_M8455_IG06
+						;; size=19 bbWeight=1 PerfScore 9.25
 G_M8455_IG03:
        mov      rdi, rsi
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_GET_GCSTATIC_BASE
        call     [rax]CORINFO_HELP_GET_GCSTATIC_BASE
-       mov      r14, gword ptr [rax]
-       mov      rdi, qword ptr [rbx]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi]
-       mov      r13, qword ptr [rsi+0x40]
-       test     r13, r13
-       je       G_M8455_IG11
-						;; size=41 bbWeight=1 PerfScore 14.75
-G_M8455_IG04:
-       mov      rdi, qword ptr [r13+0x18]
-       mov      r12, qword ptr [rdi+0x18]
-       test     r12, r12
-       je       G_M8455_IG12
-						;; size=17 bbWeight=1 PerfScore 5.25
-G_M8455_IG05:
-       mov      rdi, qword ptr [r13+0x18]
-       mov      rax, qword ptr [rdi+0x20]
-       test     rax, rax
-       je       G_M8455_IG13
-						;; size=17 bbWeight=1 PerfScore 5.25
-G_M8455_IG06:
-       mov      r13, rax
-						;; size=3 bbWeight=0.80 PerfScore 0.20
-G_M8455_IG07:
-       mov      rdi, rbx
-       mov      r11, r12
-       call     [r12]
-       mov      ecx, eax
-       mov      r11, r13
+       mov      r8, gword ptr [rax]
+       mov      rdi, gword ptr [rbx+0x08]
+       mov      ecx, dword ptr [rdi+0x20]
        mov      rsi, r15
-       mov      r8, r14
-       mov      rdi, rbx
        xor      edx, edx
-       call     [r13]
+       mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
+       call     [rax]System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
        mov      esi, eax
        test     esi, esi
-       jl       G_M8455_IG14
-						;; size=40 bbWeight=1 PerfScore 9.50
-G_M8455_IG08:
+       jl       SHORT G_M8455_IG07
+						;; size=48 bbWeight=1 PerfScore 14.75
+G_M8455_IG04:
        mov      rdi, rbx
        mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1[System.__Canon]:RemoveAt(int):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this
 						;; size=13 bbWeight=0.50 PerfScore 0.25
-G_M8455_IG09:
-       add      rsp, 8
+G_M8455_IG05:
+       add      rsp, 16
        pop      rbx
-       pop      r12
-       pop      r13
-       pop      r14
        pop      r15
        pop      rbp
        tail.jmp [rax]System.Collections.Immutable.ImmutableList`1[System.__Canon]:RemoveAt(int):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this
-						;; size=17 bbWeight=0.50 PerfScore 3.62
-G_M8455_IG10:
+						;; size=11 bbWeight=0.50 PerfScore 2.88
+G_M8455_IG06:
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
        mov      rsi, rax
-       jmp      G_M8455_IG03
-						;; size=30 bbWeight=0.20 PerfScore 1.15
-G_M8455_IG11:
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r13, rax
-       jmp      G_M8455_IG04
-						;; size=30 bbWeight=0.20 PerfScore 1.15
-G_M8455_IG12:
-       mov      rdi, r13
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      r12, rax
-       jmp      G_M8455_IG05
-						;; size=33 bbWeight=0.20 PerfScore 1.20
-G_M8455_IG13:
-       mov      rdi, r13
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      r13, rax
-       jmp      G_M8455_IG07
-						;; size=33 bbWeight=0.20 PerfScore 1.20
-G_M8455_IG14:
+       jmp      SHORT G_M8455_IG03
+						;; size=27 bbWeight=0.20 PerfScore 1.15
+G_M8455_IG07:
        mov      rax, rbx
 						;; size=3 bbWeight=0.50 PerfScore 0.12
-G_M8455_IG15:
-       add      rsp, 8
+G_M8455_IG08:
+       add      rsp, 16
        pop      rbx
-       pop      r12
-       pop      r13
-       pop      r14
        pop      r15
        pop      rbp
        ret      
-						;; size=15 bbWeight=0.50 PerfScore 2.12
+						;; size=9 bbWeight=0.50 PerfScore 1.38
 
-; Total bytes of code 341, prolog size 20, PerfScore 64.02, instruction count 90, allocated bytes for code 341 (MethodHash=457adef8) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
+; Total bytes of code 153, prolog size 17, PerfScore 35.02, instruction count 45, allocated bytes for code 153 (MethodHash=457adef8) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:Remove(System.__Canon):System.Collections.Immutable.ImmutableList`1[System.__Canon]:this (FullOpts)
 ; ============================================================

-179 (-59.87 % of base) - System.Collections.Immutable.ImmutableList`1[System.__Canon]:IndexOf(System.__Canon):int:this

 ; Assembly listing for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:IndexOf(System.__Canon):int:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
 ; rbp based frame
-; partially interruptible
+; fully interruptible
 ; No PGO data
-; 0 inlinees with PGO data; 2 single block inlinees; 1 inlinees without PGO data
+; 0 inlinees with PGO data; 5 single block inlinees; 1 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T00] (  6,  6   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
-;  V01 arg1         [V01,T08] (  3,  3   )     ref  ->  r15         class-hnd single-def <System.__Canon>
+;  V00 this         [V00,T00] (  4,  4   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
+;  V01 arg1         [V01,T02] (  3,  3   )     ref  ->  r15         class-hnd single-def <System.__Canon>
 ;# V02 OutArgs      [V02    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
-;  V03 tmp1         [V03,T11] (  3,  4   )    long  ->  r14         "spilling helperCall"
+;  V03 tmp1         [V03,T04] (  3,  4   )    long  ->  rsi         "spilling helperCall"
 ;* V04 tmp2         [V04    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
 ;* V05 tmp3         [V05    ] (  0,  0   )    long  ->  zero-ref    "Inlining Arg"
-;  V06 tmp4         [V06,T01] (  6,  6.80)    long  ->  r13         "Inlining Arg"
+;* V06 tmp4         [V06    ] (  0,  0   )    long  ->  zero-ref    "Inlining Arg"
 ;* V07 tmp5         [V07    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V08 tmp6         [V08,T02] (  4,  6   )    long  ->  r12         "spilling helperCall"
-;  V09 tmp7         [V09,T12] (  2,  4   )     ref  ->  r14         class-hnd single-def "Inlining Arg" <System.Collections.Generic.EqualityComparer`1[System.__Canon]>
-;  V10 tmp8         [V10,T03] (  4,  6   )    long  ->  r13         "spilling helperCall"
-;  V11 tmp9         [V11,T13] (  2,  4   )     int  ->  rcx         "argument with side effect"
-;  V12 rat0         [V12,T09] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V13 rat1         [V13,T04] (  3,  5.60)    long  ->  r14         "fgMakeTemp is creating a new local variable"
-;  V14 rat2         [V14,T10] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
-;  V15 rat3         [V15,T05] (  3,  5.60)    long  ->  r13         "fgMakeTemp is creating a new local variable"
-;  V16 rat4         [V16,T06] (  3,  5.60)    long  ->  r12         "fgMakeTemp is creating a new local variable"
-;  V17 rat5         [V17,T07] (  3,  5.60)    long  ->  rax         "fgMakeTemp is creating a new local variable"
+;* V08 tmp6         [V08    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V09 tmp7         [V09,T05] (  2,  4   )     ref  ->   r8         class-hnd single-def "Inlining Arg" <System.Collections.Generic.EqualityComparer`1[System.__Canon]>
+;* V10 tmp8         [V10    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V11 tmp9         [V11    ] (  0,  0   )     ref  ->  zero-ref    class-hnd exact "Inlining Arg" <System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]>
+;* V12 tmp10        [V12    ] (  0,  0   )     int  ->  zero-ref    "Inlining Arg"
+;  V13 cse0         [V13,T06] (  3,  3   )     ref  ->  rdi         "CSE #01: aggressive"
+;  V14 rat0         [V14,T03] (  3,  4.40)    long  ->  rdi         "Spilling to split statement for tree"
+;  V15 rat1         [V15,T01] (  3,  5.60)    long  ->  rsi         "fgMakeTemp is creating a new local variable"
 ;
-; Lcl frame size = 8
+; Lcl frame size = 16
 
 G_M63672_IG01:
        push     rbp
        push     r15
-       push     r14
-       push     r13
-       push     r12
        push     rbx
-       push     rax
-       lea      rbp, [rsp+0x30]
-       mov      qword ptr [rbp-0x30], rdi
+       sub      rsp, 16
+       lea      rbp, [rsp+0x20]
+       mov      qword ptr [rbp-0x18], rdi
        mov      rbx, rdi
        mov      r15, rsi
-						;; size=26 bbWeight=1 PerfScore 9.00
+						;; size=23 bbWeight=1 PerfScore 5.25
 G_M63672_IG02:
        mov      rdi, qword ptr [rbx]
        mov      rsi, qword ptr [rdi+0x30]
        mov      rsi, qword ptr [rsi]
-       mov      r14, qword ptr [rsi+0x38]
-       test     r14, r14
-       je       G_M63672_IG09
-						;; size=23 bbWeight=1 PerfScore 9.25
+       mov      rsi, qword ptr [rsi+0x38]
+       test     rsi, rsi
+       je       SHORT G_M63672_IG05
+						;; size=19 bbWeight=1 PerfScore 9.25
 G_M63672_IG03:
-       mov      rdi, qword ptr [rbx]
-       mov      rsi, qword ptr [rdi+0x30]
-       mov      rsi, qword ptr [rsi]
-       mov      r13, qword ptr [rsi+0x40]
-       test     r13, r13
-       je       G_M63672_IG10
-						;; size=23 bbWeight=1 PerfScore 9.25
-G_M63672_IG04:
-       mov      rdi, r14
+       mov      rdi, rsi
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_GET_GCSTATIC_BASE
        call     [rax]CORINFO_HELP_GET_GCSTATIC_BASE
-       mov      r14, gword ptr [rax]
-       mov      rdi, qword ptr [r13+0x18]
-       mov      r12, qword ptr [rdi+0x18]
-       test     r12, r12
-       je       G_M63672_IG11
-						;; size=35 bbWeight=1 PerfScore 10.75
-G_M63672_IG05:
-       mov      rdi, qword ptr [r13+0x18]
-       mov      rax, qword ptr [rdi+0x20]
-       test     rax, rax
-       je       G_M63672_IG12
-						;; size=17 bbWeight=1 PerfScore 5.25
-G_M63672_IG06:
-       mov      r13, rax
-						;; size=3 bbWeight=0.80 PerfScore 0.20
-G_M63672_IG07:
-       mov      rdi, rbx
-       mov      r11, r12
-       call     [r12]
-       mov      ecx, eax
-       mov      r11, r13
+       mov      r8, gword ptr [rax]
+       mov      rdi, gword ptr [rbx+0x08]
+       mov      ecx, dword ptr [rdi+0x20]
        mov      rsi, r15
-       mov      r8, r14
-       mov      rdi, rbx
        xor      edx, edx
-       mov      rax, r13
-						;; size=29 bbWeight=1 PerfScore 5.25
-G_M63672_IG08:
-       add      rsp, 8
+       mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
+						;; size=40 bbWeight=1 PerfScore 10.25
+G_M63672_IG04:
+       add      rsp, 16
        pop      rbx
-       pop      r12
-       pop      r13
-       pop      r14
        pop      r15
        pop      rbp
-       tail.jmp [rax]
-						;; size=17 bbWeight=1 PerfScore 7.25
-G_M63672_IG09:
+       tail.jmp [rax]System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
+						;; size=11 bbWeight=1 PerfScore 5.75
+G_M63672_IG05:
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r14, rax
-       jmp      G_M63672_IG03
-						;; size=30 bbWeight=0.20 PerfScore 1.15
-G_M63672_IG10:
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r13, rax
-       jmp      G_M63672_IG04
-						;; size=30 bbWeight=0.20 PerfScore 1.15
-G_M63672_IG11:
-       mov      rdi, r13
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      r12, rax
-       jmp      G_M63672_IG05
-						;; size=33 bbWeight=0.20 PerfScore 1.20
-G_M63672_IG12:
-       mov      rdi, r13
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      r13, rax
-       jmp      G_M63672_IG07
-						;; size=33 bbWeight=0.20 PerfScore 1.20
+       mov      rsi, rax
+       jmp      SHORT G_M63672_IG03
+						;; size=27 bbWeight=0.20 PerfScore 1.15
 
-; Total bytes of code 299, prolog size 20, PerfScore 60.90, instruction count 76, allocated bytes for code 299 (MethodHash=016b0747) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:IndexOf(System.__Canon):int:this (FullOpts)
+; Total bytes of code 120, prolog size 23, PerfScore 31.65, instruction count 33, allocated bytes for code 120 (MethodHash=016b0747) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:IndexOf(System.__Canon):int:this (FullOpts)
 ; ============================================================

-173 (-44.70 % of base) - System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.IList.IndexOf(System.Object):int:this

 ; Assembly listing for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.IList.IndexOf(System.Object):int:this (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
 ; rbp based frame
 ; partially interruptible
 ; No PGO data
-; 0 inlinees with PGO data; 3 single block inlinees; 1 inlinees without PGO data
+; 0 inlinees with PGO data; 6 single block inlinees; 1 inlinees without PGO data
 ; Final local variable assignments
 ;
-;  V00 this         [V00,T00] (  5,  4   )     ref  ->  rbx         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
-;  V01 arg1         [V01,T01] (  5,  3.62)     ref  ->  r15         class-hnd single-def <System.Object>
+;  V00 this         [V00,T01] (  4,  3.50)     ref  ->  r15         this class-hnd single-def <System.Collections.Immutable.ImmutableList`1[System.__Canon]>
+;  V01 arg1         [V01,T00] (  5,  3.62)     ref  ->  rbx         class-hnd single-def <System.Object>
 ;# V02 OutArgs      [V02    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
-;  V03 tmp1         [V03,T12] (  2,  2   )     ref  ->  r13         class-hnd single-def "Inlining Arg" <System.__Canon>
-;  V04 tmp2         [V04,T11] (  3,  2   )    long  ->  r15         "spilling helperCall"
+;  V03 tmp1         [V03,T06] (  2,  2   )     ref  ->  r13         class-hnd single-def "Inlining Arg" <System.__Canon>
+;  V04 tmp2         [V04,T05] (  3,  2   )    long  ->  rdi         "spilling helperCall"
 ;* V05 tmp3         [V05    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
 ;* V06 tmp4         [V06    ] (  0,  0   )    long  ->  zero-ref    "Inlining Arg"
-;  V07 tmp5         [V07,T04] (  6,  3.40)    long  ->  r12         "Inlining Arg"
+;* V07 tmp5         [V07    ] (  0,  0   )    long  ->  zero-ref    "Inlining Arg"
 ;* V08 tmp6         [V08    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
-;  V09 tmp7         [V09,T05] (  4,  3   )    long  ->  r14         "spilling helperCall"
-;  V10 tmp8         [V10,T13] (  2,  2   )     ref  ->  r15         class-hnd single-def "Inlining Arg" <System.Collections.Generic.EqualityComparer`1[System.__Canon]>
-;  V11 tmp9         [V11,T06] (  4,  3   )    long  ->  r12         "spilling helperCall"
-;  V12 tmp10        [V12,T14] (  2,  2   )     int  ->  rcx         "argument with side effect"
-;  V13 cse0         [V13,T03] (  7,  3.70)    long  ->  r14         "CSE #01: aggressive"
-;  V14 rat0         [V14,T15] (  2,  1.50)    long  ->  rdi         "Spilling to split statement for tree"
-;  V15 rat1         [V15,T02] (  5,  3.75)     ref  ->  r13         "replacement local"
-;  V16 rat2         [V16,T16] (  3,  1.25)    long  ->  rdi         "CSE for expectedClsNode"
-;  V17 rat3         [V17,T07] (  3,  2.80)    long  ->  r15         "fgMakeTemp is creating a new local variable"
-;  V18 rat4         [V18,T08] (  3,  2.80)    long  ->  r12         "fgMakeTemp is creating a new local variable"
-;  V19 rat5         [V19,T09] (  3,  2.80)    long  ->  r14         "fgMakeTemp is creating a new local variable"
-;  V20 rat6         [V20,T10] (  3,  2.80)    long  ->  rax         "fgMakeTemp is creating a new local variable"
+;* V09 tmp7         [V09    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;  V10 tmp8         [V10,T07] (  2,  2   )     ref  ->   r8         class-hnd single-def "Inlining Arg" <System.Collections.Generic.EqualityComparer`1[System.__Canon]>
+;* V11 tmp9         [V11    ] (  0,  0   )    long  ->  zero-ref    "spilling helperCall"
+;* V12 tmp10        [V12    ] (  0,  0   )     ref  ->  zero-ref    class-hnd exact "Inlining Arg" <System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]>
+;* V13 tmp11        [V13    ] (  0,  0   )     int  ->  zero-ref    "Inlining Arg"
+;  V14 cse0         [V14,T08] (  3,  1.50)     ref  ->  rdi         "CSE #02: moderate"
+;  V15 cse1         [V15,T03] (  5,  3.10)    long  ->  r14         "CSE #01: aggressive"
+;  V16 rat0         [V16,T09] (  2,  1.50)    long  ->  rdi         "Spilling to split statement for tree"
+;  V17 rat1         [V17,T02] (  5,  3.75)     ref  ->  r13         "replacement local"
+;  V18 rat2         [V18,T10] (  3,  1.25)    long  ->  rdi         "CSE for expectedClsNode"
+;  V19 rat3         [V19,T04] (  3,  2.80)    long  ->  rdi         "fgMakeTemp is creating a new local variable"
 ;
-; Lcl frame size = 8
+; Lcl frame size = 16
 
 G_M64101_IG01:
        push     rbp
        push     r15
        push     r14
        push     r13
-       push     r12
        push     rbx
-       push     rax
+       sub      rsp, 16
        lea      rbp, [rsp+0x30]
-       mov      qword ptr [rbp-0x30], rdi
-       mov      rbx, rdi
-       mov      r15, rsi
-						;; size=26 bbWeight=1 PerfScore 9.00
+       mov      qword ptr [rbp-0x28], rdi
+       mov      r15, rdi
+       mov      rbx, rsi
+						;; size=27 bbWeight=1 PerfScore 7.25
 G_M64101_IG02:
-       mov      r14, qword ptr [rbx]
+       mov      r14, qword ptr [r15]
        mov      rdi, r14
-       mov      rsi, r15
+       mov      rsi, rbx
        mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1[System.__Canon]:IsCompatibleObject(System.Object):bool
        call     [rax]System.Collections.Immutable.ImmutableList`1[System.__Canon]:IsCompatibleObject(System.Object):bool
        test     eax, eax
-       je       G_M64101_IG17
+       je       G_M64101_IG10
 						;; size=29 bbWeight=1 PerfScore 7.00
 G_M64101_IG03:
        mov      rdi, qword ptr [r14+0x30]
        mov      rdi, qword ptr [rdi]
        mov      rdi, qword ptr [rdi]
-       mov      r13, r15
+       mov      r13, rbx
        test     r13, r13
        je       SHORT G_M64101_IG06
 						;; size=18 bbWeight=0.50 PerfScore 3.75
 G_M64101_IG04:
        cmp      qword ptr [r13], rdi
        je       SHORT G_M64101_IG06
 						;; size=6 bbWeight=0.25 PerfScore 1.00
 G_M64101_IG05:
-       mov      rsi, r15
+       mov      rsi, rbx
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_CHKCASTANY
        call     [rax]CORINFO_HELP_CHKCASTANY
        mov      r13, rax
 						;; size=18 bbWeight=0.12 PerfScore 0.47
 G_M64101_IG06:
        mov      rdi, qword ptr [r14+0x30]
        mov      rdi, qword ptr [rdi]
-       mov      r15, qword ptr [rdi+0x38]
-       test     r15, r15
-       je       SHORT G_M64101_IG13
+       mov      rdi, qword ptr [rdi+0x38]
+       test     rdi, rdi
+       je       SHORT G_M64101_IG09
 						;; size=16 bbWeight=0.50 PerfScore 3.62
 G_M64101_IG07:
-       mov      rdi, qword ptr [r14+0x30]
-       mov      rdi, qword ptr [rdi]
-       mov      r12, qword ptr [rdi+0x40]
-       test     r12, r12
-       je       G_M64101_IG14
-						;; size=20 bbWeight=0.50 PerfScore 3.62
-G_M64101_IG08:
-       mov      rdi, r15
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_GET_GCSTATIC_BASE
        call     [rax]CORINFO_HELP_GET_GCSTATIC_BASE
-       mov      r15, gword ptr [rax]
-       mov      rdi, qword ptr [r12+0x18]
-       mov      r14, qword ptr [rdi+0x18]
-       test     r14, r14
-       je       G_M64101_IG15
-						;; size=36 bbWeight=0.50 PerfScore 5.38
-G_M64101_IG09:
-       mov      rdi, qword ptr [r12+0x18]
-       mov      rax, qword ptr [rdi+0x20]
-       test     rax, rax
-       je       G_M64101_IG16
-						;; size=18 bbWeight=0.50 PerfScore 2.62
-G_M64101_IG10:
-       mov      r12, rax
-						;; size=3 bbWeight=0.40 PerfScore 0.10
-G_M64101_IG11:
-       mov      rdi, rbx
-       mov      r11, r14
-       call     [r14]
-       mov      ecx, eax
-       mov      r11, r12
+       mov      r8, gword ptr [rax]
+       mov      rdi, gword ptr [r15+0x08]
+       mov      ecx, dword ptr [rdi+0x20]
        mov      rsi, r13
-       mov      r8, r15
-       mov      rdi, rbx
        xor      edx, edx
-       mov      rax, r12
-						;; size=28 bbWeight=0.50 PerfScore 2.62
-G_M64101_IG12:
-       add      rsp, 8
+       mov      rax, 0xD1FFAB1E      ; code for System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
+						;; size=37 bbWeight=0.50 PerfScore 5.00
+G_M64101_IG08:
+       add      rsp, 16
        pop      rbx
-       pop      r12
        pop      r13
        pop      r14
        pop      r15
        pop      rbp
-       tail.jmp [rax]
-						;; size=17 bbWeight=0.50 PerfScore 3.62
-G_M64101_IG13:
+       tail.jmp [rax]System.Collections.Immutable.ImmutableList`1+Node[System.__Canon]:IndexOf(System.__Canon,int,int,System.Collections.Generic.IEqualityComparer`1[System.__Canon]):int:this
+						;; size=15 bbWeight=0.50 PerfScore 3.38
+G_M64101_IG09:
        mov      rdi, r14
        mov      rsi, 0xD1FFAB1E      ; global ptr
        mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
        call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r15, rax
-       jmp      G_M64101_IG07
-						;; size=33 bbWeight=0.10 PerfScore 0.60
-G_M64101_IG14:
-       mov      rdi, r14
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_CLASS
-       mov      r12, rax
-       jmp      G_M64101_IG08
-						;; size=33 bbWeight=0.10 PerfScore 0.60
-G_M64101_IG15:
-       mov      rdi, r12
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      r14, rax
-       jmp      G_M64101_IG09
-						;; size=33 bbWeight=0.10 PerfScore 0.60
-G_M64101_IG16:
-       mov      rdi, r12
-       mov      rsi, 0xD1FFAB1E      ; global ptr
-       mov      rax, 0xD1FFAB1E      ; code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       call     [rax]CORINFO_HELP_RUNTIMEHANDLE_METHOD
-       mov      r12, rax
-       jmp      G_M64101_IG11
-						;; size=33 bbWeight=0.10 PerfScore 0.60
-G_M64101_IG17:
+       mov      rdi, rax
+       jmp      SHORT G_M64101_IG07
+						;; size=30 bbWeight=0.10 PerfScore 0.60
+G_M64101_IG10:
        mov      eax, -1
 						;; size=5 bbWeight=0.50 PerfScore 0.12
-G_M64101_IG18:
-       add      rsp, 8
+G_M64101_IG11:
+       add      rsp, 16
        pop      rbx
-       pop      r12
        pop      r13
        pop      r14
        pop      r15
        pop      rbp
        ret      
-						;; size=15 bbWeight=0.50 PerfScore 2.12
+						;; size=13 bbWeight=0.50 PerfScore 1.88
 
-; Total bytes of code 387, prolog size 20, PerfScore 47.47, instruction count 104, allocated bytes for code 387 (MethodHash=0f6c059a) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.IList.IndexOf(System.Object):int:this (FullOpts)
+; Total bytes of code 214, prolog size 21, PerfScore 34.07, instruction count 63, allocated bytes for code 214 (MethodHash=0f6c059a) for method System.Collections.Immutable.ImmutableList`1[System.__Canon]:System.Collections.IList.IndexOf(System.Object):int:this (FullOpts)
 ; ============================================================

Note: some changes were skipped as they were too large to fit into a comment.

Larger list of diffs: https://gist.github.com/MihuBot/237d9b5a3764c8991500591b85e6fecb

[MihuBot]

@hez2010