Method resolve_label_offset

cranelift/codegen/src/machinst/buffer.rs:766–781

Resolve a label to an offset, if known. May return `UNKNOWN_LABEL_OFFSET`.

(&self, mut label: MachLabel)

    /// Resolve a label to an offset, if known. May return `UNKNOWN_LABEL_OFFSET`.
    pub(crate) fn resolve_label_offset(&self, mut label: MachLabel) -> CodeOffset {
        let mut iters = 0;
        while self.label_aliases[label.0 as usize] != UNKNOWN_LABEL {
            label = self.label_aliases[label.0 as usize];
            // To protect against an infinite loop (despite our assurances to
            // ourselves that the invariants make this impossible), assert out
            // after 1M iterations. The number of basic blocks is limited
            // in most contexts anyway so this should be impossible to hit with
            // a legitimate input.
            iters += 1;
            assert!(iters < 1_000_000, "Unexpected cycle in label aliases");
        }
        self.label_offsets[label.0 as usize]

        // Post-invariant: no mutations.
    }

    /// Emit a reference to the given label with the given reference type (i.e.,
    /// branch-instruction format) at the current offset.  This is like a