br_table

br_table pops an i32 index and branches to one of several labels. Out-of-range values fall through to a default label. Useful for switch-like dispatch.

(module
  (func (param $tag i32) (result i32)
    (block $default (result i32)
      (block $case2 (result i32)
        (block $case1 (result i32)
          (block $case0 (result i32)
            (br_table $case0 $case1 $case2 $default
              (local.get $tag)))
          (return (i32.const 10)))
        (return (i32.const 20)))
      (return (i32.const 30)))
    (i32.const -1))
)

• Label order matches indices 0..n-1, then a final default.
• Each target must produce the block’s result type(s).

Instruction Reference

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