Replacing integer division by a power of 2 with an arithmetic shift or logical shift

[qjivy]

In builtin StoreFastElementIC_Standard, following code snippet will be generated:

0x7f18e20f0054  e194  00800693       li        a3, 8   
0x7f18e20f0058  e198  fb843703       ld        a4, -72(fp) 
0x7f18e20f005c  e19c  02d74733       div       a4, a4, a3

The code is from a code-assembler API, IntPtrDiv code gen from here and the lowered into Sea-of-Node machine operator Int64Div, which finally lowered by instruction selector into Div64.
But as the code snippet shows, one of its operand, or say the divider, is a constant 8, so we can use shift right to get the same result. It's a strength reduction optimization.

We can check and make the optimization.