[AArch64] Replace AND with LSL#2 for LDR target (#34101) (#89531)

Currently, process of replacing bitwise operations consisting of
`LSR`/`LSL` with `And` is performed by `DAGCombiner`.

However, in certain cases, the `AND` generated by this process
can be removed.

Consider following case:
```
        lsr x8, x8, #56
        and x8, x8, #0xfc
        ldr w0, [x2, x8]
        ret
```

In this case, we can remove the `AND` by changing the target of `LDR`
to `[X2, X8, LSL #2]` and right-shifting amount change to 56 to 58.

after changed:
```
        lsr x8, x8, #58
        ldr w0, [x2, x8, lsl #2]
        ret
```

This patch checks to see if the `SHIFTING` + `AND` operation on load
target can be optimized and optimizes it if it can.

0 files changed, 0 insertions, 0 deletions