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: instructions.rs
    path of file: ./repos/wasmtime/cranelift/codegen/src/ir
    
    the code of the file until where you have to start completion: //! Instruction formats and opcodes.
//!
//! The `instructions` module contains definitions for instruction formats, opcodes, and the
//! in-memory representation of IR instructions.
//!
//! A large part of this module is auto-generated from the instruction descriptions in the meta
//! directory.

use alloc::vec::Vec;
use core::fmt::{self, Display, Formatter};
use core::ops::{Deref, DerefMut};
use core::str::FromStr;

#[cfg(feature = "enable-serde")]
use serde_derive::{Deserialize, Serialize};

use crate::bitset::BitSet;
use crate::entity;
use crate::ir::{
    self,
    condcodes::{FloatCC, IntCC},
    trapcode::TrapCode,
    types, Block, FuncRef, MemFlags, SigRef, StackSlot, Type, Value,
};

/// Some instructions use an external list of argument values because there is not enough space in
/// the 16-byte `InstructionData` struct. These value lists are stored in a memory pool in
/// `dfg.value_lists`.
pub type ValueList = entity::EntityList<Value>;

/// Memory pool for holding value lists. See `ValueList`.
pub type ValueListPool = entity::ListPool<Value>;

/// A pair of a Block and its arguments, stored in a single EntityList internally.
///
/// NOTE: We don't expose either value_to_block or block_to_value outside of this module because
/// this operation is not generally safe. However, as the two share the same underlying layout,
/// they can be stored in the same value pool.
///
/// BlockCall makes use of this shared layout by storing all of its contents (a block and its
/// argument) in a single EntityList. This is a bit better than introducing a new entity type for
/// the pair of a block name and the arguments entity list, as we don't pay any indirection penalty
/// to get to the argument values -- they're stored in-line with the block in the same list.
///
/// The BlockCall::new function guarantees this layout by requiring a block argument that's written
/// in as the first element of the
    
    fn inst_data_is_copy() {
        fn is_copy<T: Copy>() {}
        is_copy::<InstructionData>();
    }

    #[test]
    fn inst_data_size() {
        // The size of `InstructionData` is performance sensitive, so make sure
        // we don't regress it unintentionally.
        assert_eq!(std::mem::size_of::<InstructionData>(), 16);
    }

    #[test]
    fn opcodes() {
        use core::mem;

        let x = Opcode::Iadd;
        let mut y = Opcode::Isub;

        assert!(x != y);
        y = Opcode::Iadd;
        assert_eq!(x, y);
        assert_eq!(x.format(), InstructionFormat::Binary);

        assert_eq!(format!("{:?}", Opcode::IaddImm), "IaddImm");
        assert_eq!(Opcode::IaddImm.to_string(), "iadd_imm");

        // Check the matcher.
        assert_eq!("iadd".parse::<Opcode>(), Ok(Opcode::Iadd));
        assert_eq!("iadd_imm".parse::<Opcode>(), Ok(Opcode::IaddImm));
        assert_eq!("iadd\0".parse::<Opcode>(), Err("Unknown opcode"));
        assert_eq!("".parse::<Opcode>(), Err("Unknown opcode"));
        assert_eq!("\0".parse::<Opcode>(), Err("Unknown opcode"));

        // Opcode is a single byte, and because Option<Opcode> originally came to 2 bytes, early on
        // Opcode included a variant NotAnOpcode to avoid the unnecessary bloat. Since then the Rust
        // compiler has brought in NonZero optimization, meaning that an enum not using the 0 value
        // can be optional for no size cost. We want to ensure Option<Opcode> remains small.
        assert_eq!(mem::size_of::<Opcode>(), mem::size_of::<Option<Opcode>>());
    }

    #[test]
    fn instruction_data() {
        use core::mem;
        // The size of the `InstructionData` enum is important for performance. It should not
        // exceed 16 bytes. Use `Box<FooData>` out-of-line payloads for instruction formats that
        // require more space than that. It would be fine with a data structure smaller than 16
        // bytes, but what are the odds of that?
        assert_eq!(mem::size_of::<InstructionData>(), 16);
    }

    #[test]
    fn constraints() {
        let a = Opcode::Iadd.constraints();
        assert!(a.use_typevar_operand());
        assert!(!a.requires_typevar_operand());
        assert_eq!(a.num_fixed_results(), 1);
        assert_eq!(a.num_fixed_value_arguments(), 2);
        assert_eq!(a.result_type(0, types::I32), types::I32);
        assert_eq!(a.result_type(0, types::I8), types::I8);
        assert_eq!(
            a.value_argument_constraint(0, types::I32),
            ResolvedConstraint::Bound(types::I32)
        );
        assert_eq!(
            a.value_argument_constraint(1, types::I32),
            ResolvedConstraint::Bound(types::I32)
        );

        let b = Opcode::Bitcast.constraints();
        assert!(!b.use_typevar_operand());
        assert!(!b.requires_typevar_operand());
        assert_eq!(b.num_fixed_results(), 1);
        assert_eq!(b.num_fixed_value_arguments(), 1);
        assert_eq!(b.result_type(0, types::I32), types::I32);
        assert_eq!(b.result_type(0, types::I8), types::I8);
        match b.value_argument_constraint(0, types::I32) {
            ResolvedConstraint::Free(vts) => assert!(vts.contains(types::F32)),
            _ => panic!("Unexpected constraint from value_argument_constraint"),
        }

        let c = Opcode::Call.constraints();
        assert_eq!(c.num_fixed_results(), 0);
        assert_eq!(c.num_fixed_value_arguments(), 0);

        let i = Opcode::CallIndirect.constraints();
        assert_eq!(i.num_fixed_results(), 0);
        assert_eq!(i.num_fixed_value_arguments(), 1);

        let cmp = Opcode::Icmp.constraints();
        assert!(cmp.use_typevar_operand());
        assert!(cmp.requires_typevar_operand());
        assert_eq!(cmp.num_fixed_results(), 1);
        assert_eq!(cmp.num_fixed_value_arguments(), 2);
        assert_eq!(cmp.result_type(0, types::I64), types::I8);
    }

    #[test]
    fn value_set() {
        use crate::ir::types::*;

        let vts = ValueTypeSet {
            lanes: BitSet16::from_range(0, 8),
            ints: BitSet8::from_range(4, 7),
            floats: BitSet8::from_range(0, 0),
            refs: BitSet8::from_range(5, 7),
            dynamic_lanes: BitSet16::from_range(0, 4),
        };
        assert!(!vts.contains(I8));
        assert!(vts.contains(I32));
        assert!(vts.contains(I64));
        assert!(vts.contains(I32X4));
        assert!(vts.contains(I32X4XN));
        assert!(!vts.contains(F32));
        assert!(vts.contains(R32));
        assert!(vts.contains(R64));
        assert_eq!(vts.example().to_string(), "i32");

        let vts = ValueTypeSet {
            lanes: BitSet16::from_range(0, 8),
            ints: BitSet8::from_range(0, 0),
            floats: BitSet8::from_range(5, 7),
            refs: BitSet8::from_range(0, 0),
            dynamic_lanes: BitSet16::from_range(0, 8),
        };
        assert_eq!(vts.example().to_string(), "f32");

        let vts = ValueTypeSet {
            lanes: BitSet16::from_range(1, 8),
            ints: BitSet8::from_range(0, 0),
            floats: BitSet8::from_range(5, 7),
            refs: BitSet8::from_range(0, 0),
            dynamic_lanes: BitSet16::from_range(0, 8),
        };
        assert_eq!(vts.example().to_string(), "f32x2");

        let vts = ValueTypeSet {
            lanes: BitSet16::from_range(2, 8),
            ints: BitSet8::from_range(3, 7),
            floats: BitSet8::from_range(0, 0),
            refs: BitSet8::from_range(0, 0),
            dynamic_lanes: BitSet16::from_range(0, 8),
        };
        assert_eq!(vts.example().to_string(), "i32x4");

        let vts = ValueTypeSet {
            // TypeSet(lanes=(1, 256), ints=(8, 64))
            lanes: BitSet16::from_range(0, 9),
            ints: BitSet8::from_range(3, 7),
            floats: BitSet8::from_range(0, 0),
            refs: BitSet8::from_range(0, 0),
            dynamic_lanes: BitSet16::from_range(0, 8),
        };
        assert!(vts.contains(I32));
        assert!(vts.contains(I32X4));
        assert!(!vts.contains(R32));
        assert!(!vts.contains(R64));
    }
}