load64_zero: Wasm SIMD load/store instruction

The load64_zero SIMD load/store instruction loads a single value from a given memory address into the first lane of a v128 type i64x2 value interpretation, and initializes the other lane to 0.

Try it

(module
  (import "console" "log" (func $log (param i64)))
  (memory $memory 1)
  (data (i32.const 0) "\01\02\03\04\05\06\07\08\09\0a\0b\0c\0d\0e\0f\00\01\02\03")
  (func $main
    i32.const 1
    v128.load64_zero
    i64x2.extract_lane 0
    call $log
  )
  (start $main)
)

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

Syntax

;; Common usage
v128.load64_zero

;; With optional immediate operands
v128.load64_zero mem_idx offset=int align=int

v128.load64_zero

The v128.load64_zero instruction.

mem_idx Optional

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

offset=int Optional

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

align=int Optional

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 8. 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 i64x2 value interpretation.

Binary encoding

Specifications

• WebAssembly Core Specification