The splat SIMD conversion instruction copies the same value to all lanes of a v128 value interpretation.

(module
  (import "console" "log" (func $log (param f32)))
  (func $main
    (local $s v128)
    f32.const 16.2
    f32x4.splat
    local.set $s

    local.get $s
    f32x4.extract_lane 0
    call $log ;; log the result

    local.get $s
    f32x4.extract_lane 1
    call $log ;; log the result

    local.get $s
    f32x4.extract_lane 2
    call $log ;; log the result

    local.get $s
    f32x4.extract_lane 3
    call $log ;; log the result
  )
  (start $main)
)

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

Syntax

value_type.splat

• value_type

  • : The type of value the instruction is being run on. The following v128 value interpretations support splat:

    • i8x16

    • i16x8

    • i32x4

    • i64x2

    • f32x4

    • f64x2

  splat

  • : The splat instruction. Must always be included after the value_type and a period (.).

Type

[input, value] -> [output]

• input

  • : The input v128 value interpretation.

  value

  • : The value you want to copy to all lanes of the v128.

  output

  • : The resulting v128 value interpretation after all lanes of the input value have been set to the value.

Binary encoding

InstructionBinary formatExample text => binaryi8x16.splat0xfd 15:u32i8x16.splat => 0xfd 0x0fi16x8.splat0xfd 16:u32i16x8.splat => 0xfd 0x10i32x4.splat0xfd 17:u32i32x4.splat => 0xfd 0x11i64x2.splat0xfd 18:u32i64x2.splat => 0xfd 0x12f32x4.splat0xfd 19:u32f32x4.splat => 0xfd 0x13f64x2.splat0xfd 20:u32f64x2.splat => 0xfd 0x14

Specifications

Browser compatibility