couple tweaks to optRemoveRedundantZeroInits

[VSadov]

Make the optimizer for GC locals be aware that:

• CORINFO_HELP_INIT_PINVOKE_FRAME is not a GC safe point (not any more)
• there are other helpers that are not GC safe points

This removes some unnecessary initializations.

Diffs

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[VSadov]

Example diff:

-15 (-7.54%) : 252648.dasm - (dynamicClass):IL_STUB_PInvoke(byref,byref,byref):int (FullOpts)
@@ -11,9 +11,9 @@
 ;  V01 arg1         [V01,T02] (  4,  4   )   byref  ->  rsi         single-def
 ;  V02 arg2         [V02,T03] (  4,  4   )   byref  ->  rdi         single-def
 ;* V03 loc0         [V03    ] (  0,  0   )     int  ->  zero-ref   
-;  V04 loc1         [V04    ] (  1,  1   )   byref  ->  [rbp-0x40]  must-init pinned single-def
-;  V05 loc2         [V05    ] (  1,  1   )   byref  ->  [rbp-0x48]  must-init pinned single-def
-;  V06 loc3         [V06    ] (  1,  1   )   byref  ->  [rbp-0x50]  must-init pinned single-def
+;  V04 loc1         [V04    ] (  1,  1   )   byref  ->  [rbp-0x40]  pinned single-def
+;  V05 loc2         [V05    ] (  1,  1   )   byref  ->  [rbp-0x48]  pinned single-def
+;  V06 loc3         [V06    ] (  1,  1   )   byref  ->  [rbp-0x50]  pinned single-def
 ;* V07 loc4         [V07    ] (  0,  0   )     int  ->  zero-ref   
 ;* V08 loc5         [V08    ] (  0,  0   )     int  ->  zero-ref   
 ;  V09 OutArgs      [V09    ] (  1,  1   )  struct (32) [rsp+0x00]  do-not-enreg[XS] addr-exposed "OutgoingArgSpace"
@@ -42,10 +42,6 @@ G_M13901_IG01:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref,
        push     rbx
        sub      rsp, 136
        lea      rbp, [rsp+0xC0]
-       vxorps   xmm4, xmm4, xmm4
-       vmovdqa  xmmword ptr [rbp-0x50], xmm4
-       xor      eax, eax
-       mov      qword ptr [rbp-0x40], rax
        mov      rbx, rcx
        ; byrRegs +[rbx]
        mov      rsi, rdx
@@ -53,7 +49,7 @@ G_M13901_IG01:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref,
        mov      rdi, r8
        ; byrRegs +[rdi]
        mov      r14, r10
-						;; size=54 bbWeight=1 PerfScore 13.33
+						;; size=39 bbWeight=1 PerfScore 9.75
 G_M13901_IG02:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=00C8 {rbx rsi rdi}, byref
        mov      qword ptr [rbp-0x60], r14
        lea      rcx, [rbp-0x98]
@@ -104,7 +100,7 @@ G_M13901_IG06:        ; bbWeight=1, epilog, nogc, extend
        ret      
 						;; size=20 bbWeight=1 PerfScore 5.25
 
-; Total bytes of code 199, prolog size 42, PerfScore 48.08, instruction count 56, allocated bytes for code 199 (MethodHash=7b4bc9b2) for method (dynamicClass):IL_STUB_PInvoke(byref,byref,byref):int (FullOpts)
+; Total bytes of code 184, prolog size 27, PerfScore 44.50, instruction count 52, allocated bytes for code 184 (MethodHash=7b4bc9b2) for method (dynamicClass):IL_STUB_PInvoke(byref,byref,byref):int (FullOpts)

[VSadov]

CC: @dotnet/jit-contrib

[EgorBo]

LGTM!

[VSadov]

Thanks!