Function clear_high_bits 

pub fn clear_high_bits(builder: &CircuitBuilder, w: Wire, n: u32) -> Wire

Zero the high n bits of a 64-bit word, keeping the low 64 - n bits in place.

Lowers to a left-then-right shift pair. The two shifts do not compose into one shifted operand, so gate fusion commits the intermediate and spends one constraint on it — the same count masking with a band against a constant costs today. The pair is the cheaper form only once a committed linear definition lowers to a Zero constraint rather than an AND constraint.

Example

use binius_circuits::util::clear_high_bits;
use binius_frontend::CircuitBuilder;

let builder = CircuitBuilder::new();
let word = builder.add_witness();
// Keep the low 32 bits, zeroing the high 32.
let low_half = clear_high_bits(&builder, word, 32);