Parametric Instructions

Parametric instructions operate directly on the value stack.

drop

Pop and discard the top stack value.

(module
  (func (param $x i32) (result i32)
    (drop (i32.const 123))
    (local.get $x))
)

Use drop to ignore an unused result or clean up the stack before producing a block result.

select

Choose between two values based on an i32 condition (non-zero = first value):

(module
  (func (param $a i32) (param $b i32) (param $cond i32) (result i32)
    (select (local.get $a) (local.get $b) (local.get $cond)))
)

Both candidate values must have the same type.

Instruction Reference

• Parametric Instructions — drop, select