.. index:: ! changes
.. _changes:
Change History
--------------
Since the original release 1.0 of the WebAssembly specification, a number of proposals for extensions have been integrated.
The following sections provide an overview of what has changed.
Release 2.0
~~~~~~~~~~~
.. index:: instruction, integer
Sign extension instructions
Added new numeric instructions for performing sign extension within integer representations [#proposal-signext]_.
* New :ref:`numeric instructions <syntax-instr-numeric>`:
- :math:`\K{i}\X{nn}\K{.}\EXTEND\X{N}\K{\_s}`
.. index:: instruction, trap, floating-point, integer
Non-trapping float-to-int conversions
Added new conversion instructions that avoid trapping when converting a floating-point number to an integer [#proposal-cvtsat]_.
* New :ref:`numeric instructions <syntax-instr-numeric>`:
- :math:`\K{i}\X{nn}\K{.}\TRUNC\K{\_sat\_f}\X{mm}\K{\_}\sx`
.. index:: block, function, value type, result type
Multiple values
Generalized the result type of blocks and functions to allow for multiple values; in addition, introduced the ability to have block parameters [#proposal-multivalue]_.
* :ref:`Function types <syntax-functype>` allow more than one result
* :ref:`Block types <syntax-blocktype>` can be arbitrary function types
.. index:: value type, reference, reference type, instruction, element segment
Reference types
Added |FUNCREF| and |EXTERNREF| as new value types and respective instructions [#proposal-reftype]_.
* New :ref:`reference <syntax-reftype>` :ref:`value types <syntax-valtype>`:
- |FUNCREF|
- |EXTERNREF|
* New :ref:`reference instructions <syntax-instr-ref>`:
- |REFNULL|
- |REFFUNC|
- |REFISNULL|
* Enrich :ref:`parametric instruction <syntax-instr-parametric>`:
- |SELECT| with optional type immediate
* New :ref:`declarative <syntax-elemmode>` form of :ref:`element segment <syntax-elem>`
.. index:: reference, instruction, table, table type
Table instructions
Added instructions to directly access and modify tables [#proposal-reftype]_.
* :ref:`Table types <syntax-tabletype>` allow any :ref:`reference type <syntax-reftype>` as element type
* New :ref:`table instructions <syntax-instr-table>`:
- |TABLEGET|
- |TABLESET|
- |TABLESIZE|
- |TABLEGROW|
.. index:: table, instruction, table index, element segment
Multiple tables
Added the ability to use multiple tables per module [#proposal-reftype]_.
* :ref:`Modules <syntax-module>` may
- :ref:`define <syntax-table>` multiple tables
- :ref:`import <syntax-import>` multiple tables
- :ref:`export <syntax-export>` multiple tables
* :ref:`Table instructions <syntax-instr-table>` take a :ref:`table index <syntax-tableidx>` immediate:
- |TABLEGET|
- |TABLESET|
- |TABLESIZE|
- |TABLEGROW|
- |CALLINDIRECT|
* :ref:`Element segments <syntax-elem>` take a :ref:`table index <syntax-tableidx>`
.. index:: instruction, table, memory, data segment, element segment
Bulk memory and table instructions
Added instructions that modify ranges of memory or table entries [#proposal-reftype]_ [#proposal-bulk]_
* New :ref:`memory instructions <syntax-instr-memory>`:
- |MEMORYFILL|
- |MEMORYINIT|
- |MEMORYCOPY|
- |DATADROP|
* New :ref:`table instructions <syntax-instr-table>`:
- |TABLEFILL|
- |TABLEINIT|
- |TABLECOPY|
- |ELEMDROP|
* New :ref:`passive <syntax-datamode>` form of :ref:`data segment <syntax-data>`
* New :ref:`passive <syntax-elemmode>` form of :ref:`element segment <syntax-elem>`
* New :ref:`data count section <binary-datacountsec>` in binary format
* Active data and element segments boundaries are no longer checked at compile time but may trap instead
.. index:: instructions, SIMD, value type, vector type
Vector instructions
Added vector type and instructions that manipulate multiple numeric values in parallel
(also known as *SIMD*, single instruction multiple data) [#proposal-vectype]_
* New :ref:`value type <syntax-valtype>`:
- |V128|
* New :ref:`memory instructions <syntax-instr-memory>`:
- :math:`\K{v128.}\LOAD`
- :math:`\K{v128.}\LOAD{}\!N\!\K{x}\!M\!\K{\_}\sx`
- :math:`\K{v128.}\LOAD{}N\K{\_zero}`
- :math:`\K{v128.}\LOAD{}N\K{\_splat}`
- :math:`\K{v128.}\LOAD{}N\K{\_lane}`
- :math:`\K{v128.}\STORE`
- :math:`\K{v128.}\STORE{}N\K{\_lane}`
* New constant :ref:`vector instruction <syntax-instr-vec>`:
- :math:`\K{v128.}\VCONST`
* New unary :ref:`vector instructions <syntax-instr-vec>`:
- :math:`\K{v128.not}`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.abs}`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.neg}`
- :math:`\K{i8x16.popcnt}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.abs}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.neg}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.sqrt}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.ceil}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.floor}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.trunc}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.nearest}`
* New binary :ref:`vector instructions <syntax-instr-vec>`:
- :math:`\K{v128.and}`
- :math:`\K{v128.andnot}`
- :math:`\K{v128.or}`
- :math:`\K{v128.xor}`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.add}`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.sub}`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.mul}`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.add\_sat\_}\sx`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.sub\_sat\_}\sx`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.min\_}\sx`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.max\_}\sx`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.shl}`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.shr\_}\sx`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.add}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.sub}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.mul}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.div}`
- :math:`\K{i16x8.extadd\_pairwise\_i8x16\_}\sx`
- :math:`\K{i32x4.extadd\_pairwise\_i16x8\_}\sx`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.extmul\_}\half\K{\_i}\!N'\!\K{x}\!M'\!\K{\_}\sx`
- :math:`\K{i16x8.q15mulr\_sat\_s}`
- :math:`\K{i32x4.dot\_i16x8\_s}`
- :math:`\K{i8x16.avgr\_u}`
- :math:`\K{i16x8.avgr\_u}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.min}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.max}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.pmin}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.pmax}`
* New ternary :ref:`vector instruction <syntax-instr-vec>`:
- :math:`\K{v128.bitselect}`
* New test :ref:`vector instructions <syntax-instr-vec>`:
- :math:`\K{v128.any\_true}`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.all\_true}`
* New relational :ref:`vector instructions <syntax-instr-vec>`:
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.eq}`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.ne}`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.lt\_}\sx`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.gt\_}\sx`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.le\_}\sx`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.ge\_}\sx`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.eq}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.ne}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.lt}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.gt}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.le}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.ge}`
* New conversion :ref:`vector instructions <syntax-instr-vec>`:
- :math:`\K{i32x4.trunc\_sat\_f32x4\_}\sx`
- :math:`\K{i32x4.trunc\_sat\_f64x2\_}\sx\K{\_zero}`
- :math:`\K{f32x4.convert\_i32x4\_}\sx`
- :math:`\K{f32x4.demote\_f64x2\_zero}`
- :math:`\K{f64x2.convert\_low\_i32x4\_}\sx`
- :math:`\K{f64x2.promote\_low\_f32x4}`
* New lane access :ref:`vector instructions <syntax-instr-vec>`:
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.extract\_lane\_}\sx^?`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.replace\_lane}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.extract\_lane}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.replace\_lane}`
* New lane splitting/combining :ref:`vector instructions <syntax-instr-vec>`:
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.extend\_}\half\K{\_i}\!N'\!\K{x}\!M'\!\K{\_}\sx`
- :math:`\K{i8x16.narrow\_i16x8\_}\sx`
- :math:`\K{i16x8.narrow\_i32x4\_}\sx`
* New byte reordering :ref:`vector instructions <syntax-instr-vec>`:
- :math:`\K{i8x16.shuffle}`
- :math:`\K{i8x16.swizzle}`
* New injection/projection :ref:`vector instructions <syntax-instr-vec>`:
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.splat}`
- :math:`\K{f}\!N\!\K{x}\!M\!\K{.splat}`
- :math:`\K{i}\!N\!\K{x}\!M\!\K{.bitmask}`
https://github.com/WebAssembly/spec/tree/main/proposals/sign-extension-ops/
https://github.com/WebAssembly/spec/tree/main/proposals/nontrapping-float-to-int-conversion/
https://github.com/WebAssembly/spec/tree/main/proposals/multi-value/
https://github.com/WebAssembly/spec/tree/main/proposals/reference-types/
https://github.com/WebAssembly/spec/tree/main/proposals/bulk-memory-operations/
https://github.com/WebAssembly/spec/tree/main/proposals/simd/