You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: lower_instr.go
    path of file: ./repos/wazero/internal/engine/wazevo/backend/isa/arm64
    
    the code of the file until where you have to start completion: package arm64

// Files prefixed as lower_instr** do the instruction selection, meaning that lowering SSA level instructions
// into machine specific instructions.
//
// Importantly, what the lower** functions does includes tree-matching; find the pattern from the given instruction tree,
// and merge the multiple instructions if possible. It can be considered as "N:1" in
    
func (m *machine) lowerIcmp(si *ssa.Instruction) {
	x, y, c := si.IcmpData()
	flag := condFlagFromSSAIntegerCmpCond(c)

	in64bit := x.Type().Bits() == 64
	var ext extMode
	if in64bit {
		if c.Signed() {
			ext = extModeSignExtend64
		} else {
			ext = extModeZeroExtend64
		}
	} else {
		if c.Signed() {
			ext = extModeSignExtend32
		} else {
			ext = extModeZeroExtend32
		}
	}

	rn := m.getOperand_NR(m.compiler.ValueDefinition(x), ext)
	rm := m.getOperand_Imm12_ER_SR_NR(m.compiler.ValueDefinition(y), ext)
	alu := m.allocateInstr()
	alu.asALU(aluOpSubS, operandNR(xzrVReg), rn, rm, in64bit)
	m.insert(alu)

	cset := m.allocateInstr()
	cset.asCSet(m.compiler.VRegOf(si.Return()), false, flag)
	m.insert(cset)
}