Sign-extension Operators

These operators widen integers while preserving the sign of the smaller type.

(module
  (func (export "ext8") (param $x i32) (result i32)
    (i32.extend8_s (local.get $x)))

  (func (export "ext16") (param $x i32) (result i32)
    (i32.extend16_s (local.get $x)))

  (func (export "ext32") (param $x i64) (result i64)
    (i64.extend32_s (local.get $x)))
)

Instruction Reference

• i32 Instructions — i32.extend8_s, i32.extend16_s
• i64 Instructions — i64.extend8_s, i64.extend16_s, i64.extend32_s