JIT: Move code into branch if it's side-effect free and not used elsewhere

[BoyBaykiller]

I expected the entire computation leading up to mask to be moved inside the branch. Currently it's doing all these computations unconditionally.
https://godbolt.org/z/hbadsraxd

void BitArrayIndex(int index, bool value, uint[] data)
{
    const int BITS_PER_ELEMENT = sizeof(uint) * 8;

    uint arrIndex = (uint)index / BITS_PER_ELEMENT;
    uint bitIndex = (uint)index % BITS_PER_ELEMENT;
    uint mask = 1u << (int)bitIndex;

    if (value)
    {
        data[arrIndex] |= mask;
    }
}

G_M000_IG01:                ;; offset=0x0000
       sub      rsp, 40
 
G_M000_IG02:                ;; offset=0x0004
       mov      eax, edx
       shr      eax, 5
       mov      ecx, 1
       shlx     ecx, ecx, edx
       test     r8b, r8b
       je       SHORT G_M000_IG04
 
G_M000_IG03:                ;; offset=0x0018
       cmp      eax, dword ptr [r9+0x08]
       jae      SHORT G_M000_IG05
       mov      eax, eax
       lea      rax, bword ptr [r9+4*rax+0x10]
       or       dword ptr [rax], ecx
 
G_M000_IG04:                ;; offset=0x0027
       add      rsp, 40
       ret      
 
G_M000_IG05:                ;; offset=0x002C
       call     CORINFO_HELP_RNGCHKFAIL
       int3     

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[EgorBo]

JIT lacks this class of an optimization entirely today, it's the opposite of hoisting (so sinking). Not very trivial to implement.