[RyuJIT][ARM] Redundant overflow check in "C / X"

[EgorBo]

int Test(int a) => 1000 / b; // same for 'C % b'

Current arm64 codegen:

G_M17171_IG01: 
 A9BF7BFD stp fp, lr, [sp,#-16]!
 910003FD mov fp, sp
G_M17171_IG02: 
 52807D00 mov w0, #0x3e8
 7100005F cmp w2, #0
 54000140 beq G_M17171_IG06
 3100045F cmn w2, #1
 54000081 bne G_M17171_IG03
 2B00001F adds wzr, w0, w0
 54000041 bne G_M17171_IG03 ; <-- btw, two subsequent jumps?? 
 54000086 bvs G_M17171_IG05
G_M17171_IG03: 
 1AC20C00 sdiv w0, w0, w2
G_M17171_IG04: 
 A8C17BFD ldp fp, lr, [sp],#16
 D65F03C0 ret lr
G_M17171_IG05: 
 94000000 bl CORINFO_HELP_OVERFLOW
G_M17171_IG06: 
 94000000 bl CORINFO_HELP_THROWDIVZERO
 D43E0000 bkpt
; Total bytes of code 64

As far as I understand overflow can only happen if we divide int.MinValue by -1 so it's not the case for C / x where C is not int.MinValue

Also, GT_ARRLEN can't be -1 and int.MinValue so e.g. array.Length % x or x % array.Length shouldn't produce any overflow checks as well.

category:cq
theme:div-mod-rem
skill-level:intermediate
cost:medium
impact:medium

[echesakov]

Un-assigning myself
cc @BruceForstall