Function meet_constants

src/optimise1/dataflow.rs:8–24

Meet operator for constant propagation: Merges information from multiple predecessors. A variable is constant only if it has the same constant value coming from all paths.

(map1: &ConstantMap, map2: &ConstantMap)

fn meet_constants(map1: &ConstantMap, map2: &ConstantMap) -> ConstantMap {
    let mut result = ConstantMap::default();
    // Consider variables present in map1
    for (var, const1) in map1 {
        match map2.get(var) {
            Some(const2) if const1 == const2 => {
                // Same constant value on both paths
                result.insert(var.clone(), const1.clone());
            }
            _ => {
                // Different constants or only constant on one path -> not constant after merge
            }
        }
    }
    // Variables only in map2 were already handled implicitly (won't be in result)
    result
}

pub fn analyze_constant_propagation(
    entry_label: &String,
    cfg: &HashMap<String, BasicBlockInfo>,
    // Potentially add function signature here if needed for argument constants