This reverts the revert commit f85d8a5bed
with bug fixes.
Original message:
MOVi32imm + ANDWrr ==> ANDWri + ANDWri
MOVi64imm + ANDXrr ==> ANDXri + ANDXri
The mov pseudo instruction could be expanded to multiple mov instructions later.
In this case, try to split the constant operand of mov instruction into two
bitmask immediates. It makes only two AND instructions intead of multiple
mov + and instructions.
Added a peephole optimization pass on MIR level to implement it.
Differential Revision: https://reviews.llvm.org/D109963
73a196a11c