Method add_cond_branch

cranelift/codegen/src/machinst/buffer.rs:856–890

Inform the buffer of a conditional branch at the given offset, targeting the given label. May be used to optimize branches. The last added label-use must correspond to this branch. Additional requirement: no labels may be bound between `start` and `end` (exclusive on both ends).

(
        &mut self,
        start: CodeOffset,
        end: CodeOffset,
        target: MachLabel,
        inverted: &[u8],
    )

    /// Additional requirement: no labels may be bound between `start` and `end`
    /// (exclusive on both ends).
    pub fn add_cond_branch(
        &mut self,
        start: CodeOffset,
        end: CodeOffset,
        target: MachLabel,
        inverted: &[u8],
    ) {
        debug_assert!(
            !self.open_patchable,
            "Branch instruction inserted within a patchable region"
        );
        assert!(self.cur_offset() == start);
        debug_assert!(end > start);
        assert!(!self.pending_fixup_records.is_empty());
        debug_assert!(
            inverted.len() == (end - start) as usize,
            "branch length = {}, but inverted length = {}",
            end - start,
            inverted.len()
        );
        let fixup = self.pending_fixup_records.len() - 1;
        let inverted = Some(SmallVec::from(inverted));
        self.lazily_clear_labels_at_tail();
        self.latest_branches.push(MachBranch {
            start,
            end,
            target,
            fixup,
            inverted,
            labels_at_this_branch: self.labels_at_tail.clone(),
        });

        // Post-invariant: we asserted branch start is current tail; labels at
        // branch list is cloned from list of labels at current tail.
    }

    fn truncate_last_branch(&mut self) {
        debug_assert!(