Function gen_format_constructor

cranelift/codegen/meta/src/gen_inst.rs:1042–1107

Emit a method for creating and inserting an instruction format. All instruction formats take an `opcode` argument and a `ctrl_typevar` argument for deducing the result types.

(format: &InstructionFormat, fmt: &mut Formatter)

/// All instruction formats take an `opcode` argument and a `ctrl_typevar` argument for deducing
/// the result types.
fn gen_format_constructor(format: &InstructionFormat, fmt: &mut Formatter) {
    // Construct method arguments.
    let mut args = vec![
        "self".to_string(),
        "opcode: Opcode".into(),
        "ctrl_typevar: Type".into(),
    ];

    // Raw block operands.
    args.extend((0..format.num_raw_block_operands).map(|i| format!("block{i}: ir::Block")));

    // Normal operand arguments. Start with the immediate operands.
    for f in &format.imm_fields {
        args.push(format!("{}: {}", f.member, f.kind.rust_type));
    }

    // Then the block operands.
    args.extend((0..format.num_block_operands).map(|i| format!("block{i}: ir::BlockCall")));

    // Then the value operands.
    if format.has_value_list {
        // Take all value arguments as a finished value list. The value lists
        // are created by the individual instruction constructors.
        args.push("args: ir::ValueList".into());
    } else {
        // Take a fixed number of value operands.
        for i in 0..format.num_value_operands {
            args.push(format!("arg{i}: Value"));
        }
    }

    let proto = format!(
        "{}({}) -> (Inst, &'f mut ir::DataFlowGraph)",
        format.name,
        args.join(", ")
    );

    let imms_need_masking = format
        .imm_fields
        .iter()
        .any(|f| f.kind.rust_type == "ir::immediates::Imm64");

    fmt.doc_comment(format.to_string());
    fmt.line("#[allow(non_snake_case, reason = \"generated code\")]");
    fmt.add_block(&format!("fn {proto}"), |fmt| {
        // Generate the instruction data.
        fmt.add_block(&format!(
                "let{} data = ir::InstructionData::{}",
                if imms_need_masking { " mut" } else { "" },
                format.name
            ), |fmt| {
            fmt.line("opcode,");
            gen_member_inits(format, fmt);
        });
        fmtln!(fmt, ";");

        if imms_need_masking {
            fmtln!(fmt, "data.mask_immediates(ctrl_typevar);");