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: cranelift.rs
    path of file: ./repos/rbpf/src
    
    the code of the file until where you have to start completion: // SPDX-License-Identifier: (Apache-2.0 OR MIT)

use std::{
    collections::{BTreeMap, HashMap, HashSet},
    convert::TryInto,
    io::ErrorKind,
    mem::ManuallyDrop,
};

use cranelift_codegen::{
    entity::EntityRef,
    ir::{
        condcodes::IntCC,
        types::{I16, I32, I64, I8},
        AbiParam, Block, Endianness, FuncRef, Function, InstBuilder, MemFlags, Signature,
        SourceLoc, StackSlotData, StackSlotKind, TrapCode, Type, UserFuncName, Value,
    },
    isa::OwnedTargetIsa,
    settings::{self, Configurable},
};
use cranelift_frontend::{FunctionBuilder, FunctionBuilderContext, Variable};
use cranelift_jit::{JITBuilder, JITModule};
use cranelift_module::{FuncId, Linkage, Module};

use crate::ebpf::{
    self, Insn, BPF_ALU_OP_MASK, BPF_JEQ, BPF_JGE, BPF_JGT, BPF_JLE, BPF_JLT, BPF_JMP32, BPF_JNE,
    BPF_JSET, BPF_JSGE, BPF_JSGT, BPF_JSLE, BPF_JSLT, BPF_X, STACK_SIZE, BPF_IND,
};

use super::Error;

pub type JittedFunction = extern "C" fn(
    *mut u8, // mem_ptr
    usize,   // mem_len
    *mut u8, // mbuff_ptr
    usize,   // mbuff_len
) -> u64;

pub(crate) struct CraneliftCompiler {
    isa: OwnedTargetIsa,
    module: JITModule,

    helpers: HashMap<u32, ebpf::Helper>,
    helper_func_refs: HashMap<u32, FuncRef>,

    /// List of blocks corresponding to each instruction.
    /// We only store the first instruction that observes a new block
    insn_blocks: BTreeMap<u32, Block>,
    /// Map of block targets for each jump/branching instruction.
    insn_targets: BTreeMap<u32, (Block, Block)>,
    filled_blocks: HashSet<Block>,

    /// Map of register numbers to Cranelift variables.
    registers: [Variable; 11],
    /// Other usefull variables used throughout the program.
    mem_start: Variable,
    mem_end: Variable,
    mbuf_start: Variable,
    mbuf_end: Variable,
    stack_start: Variable,
    stack_end: Variable,
}

impl CraneliftCompiler {
    pub(crate) fn new(helpers: HashMap
    
    fn build_cfg(&mut self, bcx: &mut FunctionBuilder, prog: &[u8]) -> Result<(), Error> {
        let mut insn_ptr: usize = 0;
        while insn_ptr * ebpf::INSN_SIZE < prog.len() {
            let insn = ebpf::get_insn(prog, insn_ptr);

            match insn.opc {
                // This instruction consumes two opcodes
                ebpf::LD_DW_IMM => {
                    insn_ptr += 1;
                }

                ebpf::JA
                | ebpf::JEQ_IMM
                | ebpf::JEQ_REG
                | ebpf::JGT_IMM
                | ebpf::JGT_REG
                | ebpf::JGE_IMM
                | ebpf::JGE_REG
                | ebpf::JLT_IMM
                | ebpf::JLT_REG
                | ebpf::JLE_IMM
                | ebpf::JLE_REG
                | ebpf::JNE_IMM
                | ebpf::JNE_REG
                | ebpf::JSGT_IMM
                | ebpf::JSGT_REG
                | ebpf::JSGE_IMM
                | ebpf::JSGE_REG
                | ebpf::JSLT_IMM
                | ebpf::JSLT_REG
                | ebpf::JSLE_IMM
                | ebpf::JSLE_REG
                | ebpf::JSET_IMM
                | ebpf::JSET_REG
                | ebpf::JEQ_IMM32
                | ebpf::JEQ_REG32
                | ebpf::JGT_IMM32
                | ebpf::JGT_REG32
                | ebpf::JGE_IMM32
                | ebpf::JGE_REG32
                | ebpf::JLT_IMM32
                | ebpf::JLT_REG32
                | ebpf::JLE_IMM32
                | ebpf::JLE_REG32
                | ebpf::JNE_IMM32
                | ebpf::JNE_REG32
                | ebpf::JSGT_IMM32
                | ebpf::JSGT_REG32
                | ebpf::JSGE_IMM32
                | ebpf::JSGE_REG32
                | ebpf::JSLT_IMM32
                | ebpf::JSLT_REG32
                | ebpf::JSLE_IMM32
                | ebpf::JSLE_REG32
                | ebpf::JSET_IMM32
                | ebpf::JSET_REG32
                | ebpf::EXIT
                | ebpf::TAIL_CALL => {
                    self.prepare_jump_blocks(bcx, insn_ptr, &insn);
                }
                _ => {}
            }

            insn_ptr += 1;
        }

        Ok(())
    }