Method is_block_loop_header

cranelift/codegen/src/loop_analysis.rs:195–199

Determines if a block dominates any predecessor and thus is a loop header.

(block: Block, cfg: &ControlFlowGraph, domtree: &DominatorTree)

    // Determines if a block dominates any predecessor
    // and thus is a loop header.
    fn is_block_loop_header(block: Block, cfg: &ControlFlowGraph, domtree: &DominatorTree) -> bool {
        // A block is a loop header if it dominates any of its predecessors.
        cfg.pred_iter(block)
            .any(|pred| domtree.block_dominates(block, pred.block))
    }

    // Traverses the CFG in reverse postorder and create a loop object for every block having a
    // back edge.