Function build_no_location_mask

crates/compiler-core/src/bytecode.rs:140–202

Parse linetable to build a boolean mask indicating which code units have NO_LOCATION (line == -1). Returns a Vec of length `num_units`.

(linetable: &[u8], num_units: usize)

/// Parse linetable to build a boolean mask indicating which code units
/// have NO_LOCATION (line == -1). Returns a Vec<bool> of length `num_units`.
pub fn build_no_location_mask(linetable: &[u8], num_units: usize) -> Vec<bool> {
    let mut mask = Vec::new();
    mask.resize(num_units, false);
    let mut pos = 0;
    let mut unit_idx = 0;

    while pos < linetable.len() && unit_idx < num_units {
        let header = linetable[pos];
        pos += 1;
        let code = (header >> 3) & 0xf;
        let length = ((header & 7) + 1) as usize;

        let is_no_location = code == PyCodeLocationInfoKind::None as u8;

        // Skip payload bytes based on location kind
        match code {
            0..=9 => pos += 1,   // Short forms: 1 byte payload
            10..=12 => pos += 2, // OneLine forms: 2 bytes payload
            13 => {
                // NoColumns: signed varint (line delta)
                while pos < linetable.len() {
                    let b = linetable[pos];
                    pos += 1;
                    if b & 0x40 == 0 {
                        break;
                    }
                }
            }
            14 => {
                // Long form: signed varint (line delta) + 3 unsigned varints
                // line_delta
                while pos < linetable.len() {
                    let b = linetable[pos];
                    pos += 1;
                    if b & 0x40 == 0 {
                        break;
                    }
                }
                // end_line_delta, col+1, end_col+1
                for _ in 0..3 {
                    while pos < linetable.len() {
                        let b = linetable[pos];
                        pos += 1;
                        if b & 0x40 == 0 {
                            break;
                        }
                    }
                }
            }
            15 => {} // None: no payload
            _ => {}
        }

        for _ in 0..length {
            if unit_idx < num_units {
                mask[unit_idx] = is_no_location;
                unit_idx += 1;
            }