kbjr/wasm-instructions

Reference documentation about WebAssembly instructions

WASM Instructions

Numeric

These instructions pertain to the 4 "main" numeric data types: i32, i64, f32, and f64

• const (declare constant)

• Comparisons

  • eqz (equals zero)
  • eq (equals)
  • ne (not equals)
  • lt (less than)
  • gt (greater than)
  • le (less than or equals)
  • ge (greater than or equals)

• Arithmetic

  • add (addition)
  • sub (subtraction)
  • mul (multiplication)
  • div (division)
  • rem (remainder)

• Bitwise Operations

  • clz (count leading zeros)
  • ctz (count trailing zeros)
  • popcnt (population count)
  • and (bitwise and)
  • or (bitwise or)
  • xor (bitwise xor)
  • shl (shift left)
  • shr (shift right)
  • rotl (rotate left)
  • rotr (rotate right)

• Floating Point Operations

  • abs (absolute value)
  • neg (negative)
  • ceil (ceiling / round up)
  • floor (floor / round down)
  • trunc (truncate / round toward zero)
  • nearest (round to nearest)
  • sqrt (square root)
  • min (select minimum)
  • max (select maximum)
  • copysign

• Type Convertion

  • wrap
  • trunc
  • trunc_sat
  • extend
  • convert
  • demote
  • promote
  • reinterpret

Vector / SIMD

These instructions pertain to v128 values, and their various formats.

• const (declare constant vector)
• splat (create vector with identical lanes)

• Memory

  • load
  • store

• Lane Operations

  • shuffle (shuffle together lanes from two vectors using immediate indices)
  • swizzle (swizzle lanes using stack indices)
  • extract_lane (get lane value)
  • replace_lane (set lane value)

• Comparisons

  • eq (equals)
  • ne (not equals)
  • lt (less than)
  • gt (greater than)
  • le (less than or equals)
  • ge (greater than or equals)

• Integer Arithmetic

  • add (lane-wise addition)
  • sub (lane-wise subtraction)
  • mul (lane-wise multiplication)
  • dot (lane-wise dot product)
  • neg (lane-wise negation)

• Extended Integer Arithmetic

  • extmul (extended multiplication)
  • extadd (extended pairwise addition)

• Saturating Integer Arithmetic

  • add_sat (saturating addition)
  • sub_sat (saturating subtraction)
  • q15mulr_sat (saturating Q-format rounding multiplication)
  • min (select lane-wise minimum)
  • max (select lane-wise maximum)
  • avgr (lane-wise rounding average)
  • abs (lane-wise absolute value)

• Bitwise Operations

  • not (bitwise not)
  • and (bitwise and)
  • andnot (bitwise and-not)
  • or (bitwise or)
  • xor (bitwise xor)
  • shl (lane-wise shift left)
  • shr (lane-wise shift right)
  • bitselect (bitwise select)
  • bitmask (bitmask extraction)
  • popcnt (lane-wise population count)

• Boolean Horizontal Reductions

  • any_true (any bit not zero)
  • all_true (all lanes not zero)

• Floating-point Operations

  • neg (lane-wise negation)
  • abs (lane-wise absolute value)
  • min (NaN-propagating lane-wise select minimum)
  • max (NaN-propagating lane-wise select maximum)
  • pmin (lane-wise select psuedo-minimum)
  • pmax (lane-wise select psuedo-maximum)

• Floating-point Arithmetic

  • add (addition)
  • sub (subtraction)
  • div (division)
  • mul (multiplication)
  • sqrt (square root)
  • ceil (ceiling / round up)
  • floor (floor / round down)
  • trunc (truncate / round toward zero)
  • nearest (round to nearest)

• Conversions

  • convert (convert i32 to floating-point)
  • trunc_sat (convert floating-point to i32 with saturation)
  • demote (convert f64 to f32)
  • promote (convert f32 to f64)
  • narrow (integer narrowing)
  • extend (integer extension)

Reference

• ref.null (place a null reference on the stack)
• ref.is_null (check if a reference is null)
• ref.func (place a funcref on the stack)

Parametric

• drop (drop the top value from the stack)
• select (conditionally select an operand)

Variable

• local.get (push local variable to stack)
• local.set (pop stack value and write to local variable)
• local.tee (write top of stack to local variable without pop)
• global.get (push global variable to stack)
• global.set (pop stack value and write to global variable)

Table

• table.get
• table.set
• table.size
• table.grow
• table.init
• elem.drop
• table.copy
• table.fill

Memory

• load (load a value from memory and place it on the stack)
• store (store an operand to memory)
• memory.size (get the total size of memory)
• memory.grow (request more memory)
• memory.init
• data.drop
• memory.copy
• memory.fill

Control

• unreachable (indicates an unreachable section; traps)
• nop (no-op; does nothing)
• block
• loop
• if
• else
• end
• br
• br_if
• br_table
• return
• call
• call_indirect