Extend

The extend instructions, are used to convert (extend) numbers of type i32 to type i64. There are signed and unsigned versions of this instruction.

Try it

(module
  (import "console" "log" (func $log (param i64)))
  (func $main

    i32.const 10 ;; push an i32 onto the stack

    i64.extend_i32_s ;; sign-extend from i32 to i64

    call $log ;; log the result

  )
  (start $main)
)

const url = "{%wasm-url%}";
await WebAssembly.instantiateStreaming(fetch(url), { console });

Syntax

wasm

;; push an i32 onto the stack
i32.const 10

;; sign-extend from i32 to i64
i64.extend_i32_s

;; the top item on the stack will now be the value 10 of type i64

Instruction	Binary opcode
`i64.extend_i32_s`	`0xac`
`i64.extend_i32_u`	`0xad`