JIT: Unnecessary jump into definitly-executed loop body

[BoyBaykiller]

https://www.godbolt.org/z/5b594qKd5

static int Upsilon(int a, int b)
{
    int n = 100;
    while (n > 0)
    {
        int t = a + b;
        a = b;
        b = t;
        n = n - 1;
    }
    return a;
}

Program:Upsilon(int,int):int (FullOpts):
       mov      eax, 100
       jmp      SHORT G_M57122_IG04
       align    [0 bytes for IG03]
G_M57122_IG03:  ;; offset=0x0007
       mov      r8d, ecx
       mov      ecx, edx
       mov      edx, r8d
G_M57122_IG04:  ;; offset=0x000F
       add      ecx, edx
       dec      eax
       test     eax, eax
       jg       SHORT G_M57122_IG03
       mov      ecx, edx
       mov      eax, ecx
       ret      

It emits an unconditional jmp SHORT G_M57122_IG04 into the loop body at the start of the function.
Instead it could fall into it. For example, MSVC: https://godbolt.org/z/Pr5bTn999

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[AndyAyersMS]

Might be fixed by #130368.