The load SIMD load/store instruction loads all lanes of a v128 value interpretation with values from a given memory address.

(module
  (import "console" "log" (func $log (param i32)))
  (memory $memory 1)
  (data (i32.const 0) "\00\01\02\03\04\05\06\07\08\09\0a\0b\0c\0d\0e\0f\00\01\02\03")
  (func $main
    i32.const 5
    v128.load
    i32x4.extract_lane 3
    call $log
  )
  (start $main)
)

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

Syntax

;; Common usage
v128.load

;; With optional immediate operands
v128.load mem_idx offset=int align=int

• v128.load

  • : The v128.load instruction.

  mem_idx

  • : An integer representing the memory index, in cases where the module uses multiple memories. The default is 0.

  offset=int

  • : An integer representing a constant number of bytes to add to the memory address before loading. The default is 0.

  align=int

  • : An integer representing a hint to the Wasm engine about what alignment to expect for the final address. The minimum value is 1 and the default and maximum value is 16. An align value has to be a power of 2.

Type

[memory_address] -> [output]

• memory_address

  • : An integer representing the memory address to load from.

  output

  • : The output v128 type.

Binary encoding

InstructionBinary formatExample text => binaryv128.load0xfd 0:u32 mem_idx:u8 offset:u32 align:u32v128.load 0 offset=0 align=16 => 0xfd 0x00 0x04 0x00While Wasm text format specifies the literal align value, the binary equivalent represents the exponent of the formula 2^x used to calculate the alignment. So for example, align=1 is equivalent to 0x00 (2^0), while align=16 is equivalent to 0x04 (2^4).

Specifications

Browser compatibility