[JitDiff X64] [xtqqczze] Optimise `Guid.DecodeByte`

[MihuBot]

Job completed in 15 minutes 33 seconds (remote runner delay: 47 seconds).
dotnet/runtime#116574

Diffs

Found 83 files with textual diffs.

Summary of Code Size diffs:
(Lower is better)

Total bytes of base: 40531548
Total bytes of diff: 40530703
Total bytes of delta: -845 (-0.00 % of base)
Total relative delta: -0.93
    diff is an improvement.
    relative diff is an improvement.


Top file improvements (bytes):
        -845 : System.Private.CoreLib.dasm (-0.01 % of base)

1 total files with Code Size differences (1 improved, 0 regressed), 259 unchanged.

Top method improvements (bytes):
        -348 (-29.19 % of base) : System.Private.CoreLib.dasm - System.Guid:TryParseExactD[byte](System.ReadOnlySpan`1[byte],byref):bool (FullOpts)
        -333 (-29.65 % of base) : System.Private.CoreLib.dasm - System.Guid:TryParseExactN[byte](System.ReadOnlySpan`1[byte],byref):bool (FullOpts)
        -150 (-12.21 % of base) : System.Private.CoreLib.dasm - System.Guid:TryParseExactD[char](System.ReadOnlySpan`1[char],byref):bool (FullOpts)
         -14 (-21.88 % of base) : System.Private.CoreLib.dasm - System.Guid:DecodeByte[byte](byte,byte,byref):byte (FullOpts)

Top method improvements (percentages):
        -333 (-29.65 % of base) : System.Private.CoreLib.dasm - System.Guid:TryParseExactN[byte](System.ReadOnlySpan`1[byte],byref):bool (FullOpts)
        -348 (-29.19 % of base) : System.Private.CoreLib.dasm - System.Guid:TryParseExactD[byte](System.ReadOnlySpan`1[byte],byref):bool (FullOpts)
         -14 (-21.88 % of base) : System.Private.CoreLib.dasm - System.Guid:DecodeByte[byte](byte,byte,byref):byte (FullOpts)
        -150 (-12.21 % of base) : System.Private.CoreLib.dasm - System.Guid:TryParseExactD[char](System.ReadOnlySpan`1[char],byref):bool (FullOpts)

4 total methods with Code Size differences (4 improved, 0 regressed), 246136 unchanged.

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

Artifacts:

• build-clr-checked-main.zip (87 MB)
• build-artifacts-main.zip (674 MB)
• build-clr-checked-pr.zip (87 MB)
• build-artifacts-pr.zip (675 MB)
• jit-diffs-main.zip (135 MB)
• jit-diffs-pr.zip (135 MB)
• diff-frameworks.txt (1 KB)
• ShortDiffsImprovements.md (5 KB)
• LongDiffsImprovements.md (266 KB)

[xtqqczze]

xtqqczze/dotnet-runtime@db859fd

[MihuBot]

Top method improvements

-14 (-21.88 % of base) - System.Guid:DecodeByte[byte](byte,byte,byref):byte

 ; Assembly listing for method System.Guid:DecodeByte[byte](byte,byte,byref):byte (FullOpts)
 ; Emitting BLENDED_CODE for generic X64 + VEX + EVEX on Unix
 ; FullOpts code
 ; optimized code
-; rsp based frame
+; rbp based frame
 ; partially interruptible
 ; No PGO data
-; 0 inlinees with PGO data; 3 single block inlinees; 3 inlinees without PGO data
+; 0 inlinees with PGO data; 3 single block inlinees; 1 inlinees without PGO data
 ; Final local variable assignments
 ;
 ;  V00 arg0         [V00,T01] (  3,  3   )   ubyte  ->  rdi         single-def
 ;  V01 arg1         [V01,T02] (  3,  3   )   ubyte  ->  rsi         single-def
 ;  V02 arg2         [V02,T00] (  4,  4   )   byref  ->  rdx         single-def
 ;* V03 loc0         [V03    ] (  0,  0   )  struct (16) zero-ref    ld-addr-op <System.ReadOnlySpan`1[byte]>
-;* V04 loc1         [V04    ] (  0,  0   )     int  ->  zero-ref   
-;  V05 loc2         [V05,T10] (  2,  2   )     int  ->  rcx        
+;  V04 loc1         [V04,T05] (  2,  2   )     int  ->  rax        
+;  V05 loc2         [V05,T06] (  2,  2   )     int  ->  rcx        
 ;* V06 loc3         [V06    ] (  0,  0   )     int  ->  zero-ref   
-;# V07 OutArgs      [V07    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
-;  V08 tmp1         [V08,T03] (  2,  4   )     int  ->  rcx         "Span.get_Item index"
-;  V09 tmp2         [V09,T04] (  2,  4   )     int  ->  rcx         "impAppendStmt"
-;  V10 tmp3         [V10,T05] (  2,  4   )     int  ->   r8         "Span.get_Item index"
-;* V11 tmp4         [V11    ] (  0,  0   )     int  ->  zero-ref    "impAppendStmt"
-;  V12 tmp5         [V12,T06] (  3,  3   )     int  ->  rcx        
-;* V13 tmp6         [V13    ] (  0,  0   )  struct (16) zero-ref    ld-addr-op "NewObj constructor temp" <System.ReadOnlySpan`1[byte]>
-;* V14 tmp7         [V14    ] (  0,  0   )   ubyte  ->  zero-ref    ld-addr-op "Inline stloc first use temp"
-;* V15 tmp8         [V15    ] (  0,  0   )   ubyte  ->  zero-ref    ld-addr-op "Inline stloc first use temp"
-;* V16 tmp9         [V16    ] (  0,  0   )   byref  ->  zero-ref    single-def "field V03._reference (fldOffset=0x0)" P-INDEP
-;* V17 tmp10        [V17    ] (  0,  0   )     int  ->  zero-ref    "field V03._length (fldOffset=0x8)" P-INDEP
-;* V18 tmp11        [V18    ] (  0,  0   )   byref  ->  zero-ref    single-def "field V13._reference (fldOffset=0x0)" P-INDEP
-;* V19 tmp12        [V19    ] (  0,  0   )     int  ->  zero-ref    "field V13._length (fldOffset=0x8)" P-INDEP
-;  V20 cse0         [V20,T07] (  3,  3   )    long  ->  rdi         "CSE #01: moderate"
-;  V21 cse1         [V21,T08] (  3,  3   )     int  ->  rax         "CSE #02: moderate"
-;  V22 cse2         [V22,T09] (  3,  3   )     int  ->  rsi         "CSE #03: moderate"
+;  V07 loc4         [V07,T03] (  3,  3   )     int  ->  rax        
+;# V08 OutArgs      [V08    ] (  1,  1   )  struct ( 0) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace" <Empty>
+;* V09 tmp1         [V09    ] (  0,  0   )     int  ->  zero-ref   
+;* V10 tmp2         [V10    ] (  0,  0   )     int  ->  zero-ref   
+;* V11 tmp3         [V11    ] (  0,  0   )     int  ->  zero-ref    "impAppendStmt"
+;* V12 tmp4         [V12    ] (  0,  0   )  struct (16) zero-ref    ld-addr-op "NewObj constructor temp" <System.ReadOnlySpan`1[byte]>
+;* V13 tmp5         [V13    ] (  0,  0   )   byref  ->  zero-ref    single-def "field V03._reference (fldOffset=0x0)" P-INDEP
+;* V14 tmp6         [V14    ] (  0,  0   )     int  ->  zero-ref    "field V03._length (fldOffset=0x8)" P-INDEP
+;* V15 tmp7         [V15    ] (  0,  0   )   byref  ->  zero-ref    single-def "field V12._reference (fldOffset=0x0)" P-INDEP
+;* V16 tmp8         [V16    ] (  0,  0   )     int  ->  zero-ref    "field V12._length (fldOffset=0x8)" P-INDEP
+;  V17 cse0         [V17,T04] (  3,  3   )    long  ->  rdi         "CSE #01: aggressive"
 ;
 ; Lcl frame size = 0
 
 G_M7685_IG01:
-						;; size=0 bbWeight=1 PerfScore 0.00
+       push     rbp
+       mov      rbp, rsp
+						;; size=4 bbWeight=1 PerfScore 1.25
 G_M7685_IG02:
        movzx    rax, dil
-       mov      ecx, eax
+       movzx    rcx, sil
        mov      rdi, 0xD1FFAB1E      ; static handle
+       movzx    rax, byte  ptr [rax+rdi]
+       movsx    rax, al
+       shl      eax, 4
        movzx    rcx, byte  ptr [rcx+rdi]
        movsx    rcx, cl
-       movzx    rsi, sil
-       mov      r8d, esi
-       movzx    rdi, byte  ptr [r8+rdi]
-       movsx    rdi, dil
-       shl      ecx, 4
-       or       ecx, edi
-       or       eax, esi
-       mov      edi, -1
-       shr      eax, 8
-       cmovne   ecx, edi
-       or       dword ptr [rdx], ecx
-       movzx    rax, cl
-						;; size=63 bbWeight=1 PerfScore 11.00
+       or       eax, ecx
+       or       dword ptr [rdx], eax
+       movzx    rax, al
+						;; size=44 bbWeight=1 PerfScore 9.25
 G_M7685_IG03:
+       pop      rbp
        ret      
-						;; size=1 bbWeight=1 PerfScore 1.00
+						;; size=2 bbWeight=1 PerfScore 1.50
 
-; Total bytes of code 64, prolog size 0, PerfScore 12.00, instruction count 18, allocated bytes for code 64 (MethodHash=3108e1fa) for method System.Guid:DecodeByte[byte](byte,byte,byref):byte (FullOpts)
+; Total bytes of code 50, prolog size 4, PerfScore 12.00, instruction count 15, allocated bytes for code 50 (MethodHash=3108e1fa) for method System.Guid:DecodeByte[byte](byte,byte,byref):byte (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/64dd3ecda12694e2470a4b2c66af2fa9

[MihuBot]

@xtqqczze