Method add_uncond_branch

cranelift/codegen/src/machinst/buffer.rs:827–848

Inform the buffer of an unconditional 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. This must be called when the current offset is equal to `start`; i.e., before actually emitting the branch. This implies that for a branch that uses a label and is eligible for optimizations by the MachBuffer, the pr

(&mut self, start: CodeOffset, end: CodeOffset, target: MachLabel)

    /// Additional requirement: no labels may be bound between `start` and `end`
    /// (exclusive on both ends).
    pub fn add_uncond_branch(&mut self, start: CodeOffset, end: CodeOffset, target: MachLabel) {
        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());
        let fixup = self.pending_fixup_records.len() - 1;
        self.lazily_clear_labels_at_tail();
        self.latest_branches.push(MachBranch {
            start,
            end,
            target,
            fixup,
            inverted: None,
            labels_at_this_branch: self.labels_at_tail.clone(),
        });

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

    /// Inform the buffer of a conditional branch at the given offset,
    /// targeting the given label. May be used to optimize branches.