Function mem2reg

crates/rustc_codegen_spirv/src/linker/mem2reg.rs:20–46

(
    header: &mut ModuleHeader,
    types_global_values: &mut Vec<Instruction>,
    pointer_to_pointee: &FxHashMap<Word, Word>,
    constants: &FxHashMap<Word, u32>,
    func: &mut Function,
)

use std::collections::hash_map;

pub fn mem2reg(
    header: &mut ModuleHeader,
    types_global_values: &mut Vec<Instruction>,
    pointer_to_pointee: &FxHashMap<Word, Word>,
    constants: &FxHashMap<Word, u32>,
    func: &mut Function,
) {
    let reachable = compute_reachable(&func.blocks);
    let preds = compute_preds(&func.blocks, &reachable);
    let idom = compute_idom(&preds, &reachable);
    let dominance_frontier = compute_dominance_frontier(&preds, &idom);
    loop {
        let changed = insert_phis_all(
            header,
            types_global_values,
            pointer_to_pointee,
            constants,
            &mut func.blocks,
            &dominance_frontier,
        );
        if !changed {
            break;
        }
        // mem2reg produces minimal SSA form, not pruned, so DCE the dead ones
        super::dce::dce_phi(func);
    }
}

fn label_to_index(blocks: &[Block], id: Word) -> usize {
    blocks