The replace_lane SIMD conversion instruction replaces the specified lane of a v128 value interpretation with a new value and returns the resulting v128 value interpretation.

(module
  (import "console" "log" (func $log (param f64)))
  (func $main
    v128.const f64x2 1200000 3456789
    f64.const 777777

    f64x2.replace_lane 1
    f64x2.extract_lane 1
    call $log ;; log the result
  )
  (start $main)
)

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

Syntax

value_type.replace_lane index

• value_type

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

    • i8x16

    • i16x8

    • i32x4

    • i64x2

    • f32x4

    • f64x2

  replace_lane

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

  index

  • : The index of the lane that you want to replace.

Type

[input, replace_value] -> [output]

• input

  • : The input v128 value interpretation.

  replace_value

  • : The value that you want to replace the lane with.

  output

  • : The output v128 value interpretation.

Binary encoding

InstructionBinary formatExample text => binaryi8x16.replace_lane0xfd 23:u32 l:lane_idxi8x16.replace_lane 3 => 0xfd 0x17 0x03i16x8.replace_lane0xfd 26:u32 l:lane_idxi16x8.replace_lane 3 => 0xfd 0x1a 0x03i32x4.replace_lane0xfd 28:u32 l:lane_idxi32x4.replace_lane 3 => 0xfd 0x1c 0x03i64x2.replace_lane0xfd 30:u32 l:lane_idxi64x2.replace_lane 1 => 0xfd 0x1e 0x01f32x4.replace_lane0xfd 32:u32 l:lane_idxf32x4.replace_lane 3 => 0xfd 0x20 0x03f64x2.replace_lane0xfd 34:u32 l:lane_idxf64x2.replace_lane 1 => 0xfd 0x22 0x01

Specifications

Browser compatibility

See also

• extract_lane