Function fuse_bool

crates/rustc_codegen_spirv/src/linker/peephole_opts.rs:509–551

(
    header: &mut ModuleHeader,
    defs: &FxHashMap<Word, (usize, Instruction)>,
    phis_to_insert: &mut Vec<(usize, Instruction)>,
    already_mapped: &mut FxHashMap<Word, Word>,
    bool_ty: Word

}

fn fuse_bool(
    header: &mut ModuleHeader,
    defs: &FxHashMap<Word, (usize, Instruction)>,
    phis_to_insert: &mut Vec<(usize, Instruction)>,
    already_mapped: &mut FxHashMap<Word, Word>,
    bool_ty: Word,
    int_value: Word,
) -> Word {
    if let Some(&result) = already_mapped.get(&int_value) {
        return result;
    }
    let (block_of_inst, inst) = defs.get(&int_value).unwrap();
    match inst.class.opcode {
        Op::Select => inst.operands[0].unwrap_id_ref(),
        Op::Phi => {
            let result_id = id(header);
            already_mapped.insert(int_value, result_id);
            let new_phi_args = inst
                .operands
                .chunks(2)
                .flat_map(|arr| {
                    let phi_value = &arr[0];
                    let block = &arr[1];
                    [
                        Operand::IdRef(fuse_bool(
                            header,
                            defs,
                            phis_to_insert,
                            already_mapped,
                            bool_ty,
                            phi_value.unwrap_id_ref(),
                        )),
                        block.clone(),
                    ]
                })
                .collect::<Vec<_>>();
            let inst = Instruction::new(Op::Phi, Some(bool_ty), Some(result_id), new_phi_args);
            phis_to_insert.push((*block_of_inst, inst));
            result_id
        }
        _ => bug!("can_fuse_bool should have prevented this case"),
    }
}

// The compiler generates a lot of code that looks like this:
// %v_int = OpSelect %int %v %const_1 %const_0