br & br_if

br performs an unconditional jump to the end of a block or to the top of a loop. br_if pops a condition and branches if non-zero.

(module
  (func (param $n i32) (result i32)
    (block $exit (result i32)
      (br_if $exit (i32.gt_s (local.get $n) (i32.const 10)))
      (i32.const 1)
      (br $exit)))
)

Relative labels — br 0 targets the innermost label, br 1 jumps one level out:

(module
  (func (result i32)
    (block (result i32)
      (block (result i32)
        (i32.const 42)
        (br 1))))
)

Instruction Reference

• Control Flow Instructions — block, loop, if, br, br_if