Method dominates

cranelift/codegen/src/dominator_tree.rs:251–289

Returns `true` if `a` dominates `b`. This means that every control-flow path from the function entry to `b` must go through `a`. Dominance is ill defined for unreachable blocks. This function can always determine dominance for instructions in the same block, but otherwise returns `false` if either block is unreachable. An instruction is considered to dominate itself. A block is also considered

(&self, a: A, b: B, layout: &Layout)

    /// An instruction is considered to dominate itself.
    /// A block is also considered to dominate itself.
    pub fn dominates<A, B>(&self, a: A, b: B, layout: &Layout) -> bool
    where
        A: Into<ProgramPoint>,
        B: Into<ProgramPoint>,
    {
        let a = a.into();
        let b = b.into();
        match a {
            ProgramPoint::Block(block_a) => match b {
                ProgramPoint::Block(block_b) => self.block_dominates(block_a, block_b),
                ProgramPoint::Inst(inst_b) => {
                    let block_b = layout
                        .inst_block(inst_b)
                        .expect("Instruction not in layout.");
                    self.block_dominates(block_a, block_b)
                }
            },
            ProgramPoint::Inst(inst_a) => {
                let block_a: Block = layout
                    .inst_block(inst_a)
                    .expect("Instruction not in layout.");
                match b {
                    ProgramPoint::Block(block_b) => {
                        block_a != block_b && self.block_dominates(block_a, block_b)
                    }
                    ProgramPoint::Inst(inst_b) => {
                        let block_b = layout
                            .inst_block(inst_b)
                            .expect("Instruction not in layout.");
                        if block_a == block_b {
                            layout.pp_cmp(a, b) != Ordering::Greater
                        } else {
                            self.block_dominates(block_a, block_b)
                        }
                    }
                }
            }
        }
    }

    /// Returns `true` if `block_a` dominates `block_b`.
    ///