Method common_dominator

cranelift/codegen/src/dominator_tree/simple.rs:172–192

Compute the common dominator of two basic blocks. Both basic blocks are assumed to be reachable.

(&self, mut a: Block, mut b: Block)

    ///
    /// Both basic blocks are assumed to be reachable.
    fn common_dominator(&self, mut a: Block, mut b: Block) -> Block {
        loop {
            match self.rpo_cmp_block(a, b) {
                Ordering::Less => {
                    // `a` comes before `b` in the RPO. Move `b` up.
                    let idom = self.nodes[b].idom.expect("Unreachable basic block?");
                    b = idom;
                }
                Ordering::Greater => {
                    // `b` comes before `a` in the RPO. Move `a` up.
                    let idom = self.nodes[a].idom.expect("Unreachable basic block?");
                    a = idom;
                }
                Ordering::Equal => break,
            }
        }

        debug_assert_eq!(a, b, "Unreachable block passed to common_dominator?");

        a
    }
}

impl SimpleDominatorTree {