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¶

Sign Extension Instructions¶

Added new numeric instructions for performing sign extension within integer representations. [1]

New numeric instructions:
- \(\mathsf{i}\mathit{nn}\mathsf{.}\href{../syntax/instructions.html#syntax-instr-numeric}{\mathsf{extend}}\mathit{N}\mathsf{\_s}\)

Non-trapping Float-to-Int Conversions¶

Added new conversion instructions that avoid trapping when converting a floating-point number to an integer. [2]

New numeric instructions:
- \(\mathsf{i}\mathit{nn}\mathsf{.}\href{../syntax/instructions.html#syntax-instr-numeric}{\mathsf{trunc}}\mathsf{\_sat\_f}\mathit{mm}\mathsf{\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)

Multiple Values¶

Generalized the result type of blocks and functions to allow for multiple values; in addition, introduced the ability to have block parameters. [3]

Function types allow more than one result
Block types can be arbitrary function types

Reference Types¶

Added \(\href{../syntax/types.html#syntax-reftype}{\mathsf{funcref}}\) and \(\href{../syntax/types.html#syntax-reftype}{\mathsf{externref}}\) as new value types and respective instructions. [4]

New reference value types:
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{funcref}}\)
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{externref}}\)
New reference instructions:
- \(\href{../syntax/instructions.html#syntax-instr-ref}{\mathsf{ref{.}null}}\)
- \(\href{../syntax/instructions.html#syntax-instr-ref}{\mathsf{ref{.}func}}\)
- \(\href{../syntax/instructions.html#syntax-instr-ref}{\mathsf{ref{.}is\_null}}\)
Extended parametric instruction:
- \(\href{../syntax/instructions.html#syntax-instr-parametric}{\mathsf{select}}\) with optional type immediate
New declarative form of element segment

Table Instructions¶

Added instructions to directly access and modify tables. [4]

Table types allow any reference type as element type
New table instructions:
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}get}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}set}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}size}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}grow}}\)

Multiple Tables¶

Added the ability to use multiple tables per module. [4]

Modules may
- define multiple tables
- import multiple tables
- export multiple tables
Table instructions take a table index immediate:
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}get}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}set}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}size}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}grow}}\)
- \(\href{../syntax/instructions.html#syntax-instr-control}{\mathsf{call\_indirect}}\)
Element segments take a table index

Bulk Memory and Table Instructions¶

Added instructions that modify ranges of memory or table entries. [4] [5]

New memory instructions:
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}fill}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}init}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}copy}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{data{.}drop}}\)
New table instructions:
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}fill}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}init}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}copy}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{elem{.}drop}}\)
New passive form of data segment
New passive form of element segment
New data count section in binary format
Active data and element segments boundaries are no longer checked at compile time but may trap instead

Vector Instructions¶

Added vector type and instructions that manipulate multiple numeric values in parallel (also known as SIMD, single instruction multiple data) [6]

New value type:
- \(\href{../syntax/types.html#syntax-vectype}{\mathsf{v\scriptstyle128}}\)
New memory instructions:
- \(\mathsf{v128.}\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{load}}\)
- \(\mathsf{v128.}\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{load}}{}\!N\!\mathsf{x}\!M\!\mathsf{\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{v128.}\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{load}}{}N\mathsf{\_zero}\)
- \(\mathsf{v128.}\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{load}}{}N\mathsf{\_splat}\)
- \(\mathsf{v128.}\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{load}}{}N\mathsf{\_lane}\)
- \(\mathsf{v128.}\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{store}}\)
- \(\mathsf{v128.}\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{store}}{}N\mathsf{\_lane}\)
New constant vector instruction:
- \(\mathsf{v128.}\href{../syntax/instructions.html#syntax-instr-vec}{\mathsf{const}}\)
New unary vector instructions:
- \(\mathsf{v128.not}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.abs}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.neg}\)
- \(\mathsf{i8x16.popcnt}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.abs}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.neg}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.sqrt}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.ceil}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.floor}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.trunc}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.nearest}\)
New binary vector instructions:
- \(\mathsf{v128.and}\)
- \(\mathsf{v128.andnot}\)
- \(\mathsf{v128.or}\)
- \(\mathsf{v128.xor}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.add}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.sub}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.mul}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.add\_sat\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.sub\_sat\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.min\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.max\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.shl}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.shr\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.add}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.sub}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.mul}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.div}\)
- \(\mathsf{i16x8.extadd\_pairwise\_i8x16\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i32x4.extadd\_pairwise\_i16x8\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.extmul\_}\href{../syntax/instructions.html#syntax-half}{\mathit{half}}\mathsf{\_i}\!N'\!\mathsf{x}\!M'\!\mathsf{\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i16x8.q15mulr\_sat\_s}\)
- \(\mathsf{i32x4.dot\_i16x8\_s}\)
- \(\mathsf{i8x16.avgr\_u}\)
- \(\mathsf{i16x8.avgr\_u}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.min}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.max}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.pmin}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.pmax}\)
New ternary vector instruction:
- \(\mathsf{v128.bitselect}\)
New test vector instructions:
- \(\mathsf{v128.any\_true}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.all\_true}\)
New relational vector instructions:
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.eq}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.ne}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.lt\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.gt\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.le\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.ge\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.eq}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.ne}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.lt}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.gt}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.le}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.ge}\)
New conversion vector instructions:
- \(\mathsf{i32x4.trunc\_sat\_f32x4\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i32x4.trunc\_sat\_f64x2\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\mathsf{\_zero}\)
- \(\mathsf{f32x4.convert\_i32x4\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{f32x4.demote\_f64x2\_zero}\)
- \(\mathsf{f64x2.convert\_low\_i32x4\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{f64x2.promote\_low\_f32x4}\)
New lane access vector instructions:
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.extract\_lane\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}^?\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.replace\_lane}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.extract\_lane}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.replace\_lane}\)
New lane splitting/combining vector instructions:
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.extend\_}\href{../syntax/instructions.html#syntax-half}{\mathit{half}}\mathsf{\_i}\!N'\!\mathsf{x}\!M'\!\mathsf{\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i8x16.narrow\_i16x8\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i16x8.narrow\_i32x4\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
New byte reordering vector instructions:
- \(\mathsf{i8x16.shuffle}\)
- \(\mathsf{i8x16.swizzle}\)
New injection/projection vector instructions:
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.splat}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.splat}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.bitmask}\)

Release 3.0¶

Extended Constant Expressions¶

Allowed basic numeric computations in constant expressions. [7]

Extended set of constant instructions with:
- \(\mathsf{i}\mathit{nn}\mathsf{.add}\)
- \(\mathsf{i}\mathit{nn}\mathsf{.sub}\)
- \(\mathsf{i}\mathit{nn}\mathsf{.mul}\)
- \(\href{../syntax/instructions.html#syntax-instr-variable}{\mathsf{global{.}get}}\) for any previously declared immutable global

Note

The garbage collection added further constant instructions.

Tail Calls¶

Added instructions to perform tail calls. [8]

New control instructions:
- \(\href{../syntax/instructions.html#syntax-instr-control}{\mathsf{return\_call}}\)
- \(\href{../syntax/instructions.html#syntax-instr-control}{\mathsf{return\_call\_indirect}}\)

Exception Handling¶

Added tag definitions, imports, and exports, and instructions to throw and catch exceptions [9]

Modules may
- define tags
- import tags
- export tags
New heap types:
- \(\href{../syntax/types.html#syntax-heaptype}{\mathsf{exn}}\)
- \(\href{../syntax/types.html#syntax-heaptype}{\mathsf{noexn}}\)
New reference type short-hands:
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{exnref}}\)
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{nullexnref}}\)
New control instructions:
- \(\href{../syntax/instructions.html#syntax-instr-control}{\mathsf{throw}}\)
- \(\href{../syntax/instructions.html#syntax-instr-control}{\mathsf{throw\_ref}}\)
- \(\href{../syntax/instructions.html#syntax-instr-control}{\mathsf{try\_table}}\)
New tag section in binary format.

Multiple Memories¶

Added the ability to use multiple memories per module. [10]

Modules may
- define multiple memories
- import multiple memories
- export multiple memories
Memory instructions take a memory index immediate:
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}size}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}grow}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}fill}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}copy}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}init}}\)
- \(t\mathsf{.load}\)
- \(t\mathsf{.store}\)
- \(t\mathsf{.load}\!N\!\mathsf{\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(t\mathsf{.store}\!N\)
- \(\mathsf{v128.load}\!N\!\mathsf{x}\!M\!\mathsf{\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{v128.load}\!N\!\mathsf{\_zero}\)
- \(\mathsf{v128.load}\!N\!\mathsf{\_splat}\)
- \(\mathsf{v128.load}\!N\!\mathsf{\_lane}\)
- \(\mathsf{v128.store}\!N\!\mathsf{\_lane}\)
Data segments take a memory index

64-bit Address Space¶

Added the ability to declare an \(\href{../syntax/types.html#syntax-numtype}{\mathsf{i\scriptstyle64}}\) address type for tables and memories. [11]

Address types denote a subset of the integral number types
Table types include an address type
Memory types include an address type
Operand types of table and memory instructions now depend on the subject’s declared address type:
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}get}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}set}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}size}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}grow}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}fill}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}copy}}\)
- \(\href{../syntax/instructions.html#syntax-instr-table}{\mathsf{table{.}init}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}size}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}grow}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}fill}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}copy}}\)
- \(\href{../syntax/instructions.html#syntax-instr-memory}{\mathsf{memory{.}init}}\)
- \(t\mathsf{.load}\)
- \(t\mathsf{.store}\)
- \(t\mathsf{.load}\!N\!\mathsf{\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(t\mathsf{.store}\!N\)
- \(\mathsf{v128.load}\!N\!\mathsf{x}\!M\!\mathsf{\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{v128.load}\!N\!\mathsf{\_zero}\)
- \(\mathsf{v128.load}\!N\!\mathsf{\_splat}\)
- \(\mathsf{v128.load}\!N\!\mathsf{\_lane}\)
- \(\mathsf{v128.store}\!N\!\mathsf{\_lane}\)

Typeful References¶

Added more precise types for references. [12]

New generalised form of reference types:
- \((\href{../syntax/types.html#syntax-reftype}{\mathsf{ref}}~\href{../syntax/types.html#syntax-reftype}{\mathsf{null}}^?~\href{../syntax/types.html#syntax-heaptype}{\mathit{heaptype}})\)
New class of heap types:
- \(\href{../syntax/modules.html#syntax-func}{\mathsf{func}}\)
- \(\href{../syntax/types.html#syntax-heaptype}{\mathsf{extern}}\)
- \(\href{../syntax/modules.html#syntax-typeidx}{\mathit{typeidx}}\)
Basic subtyping on reference and value types
New reference instructions:
- \(\href{../syntax/instructions.html#syntax-instr-ref}{\mathsf{ref{.}as\_non\_null}}\)
- \(\href{../syntax/instructions.html#syntax-instr-control}{\mathsf{br\_on\_null}}\)
- \(\href{../syntax/instructions.html#syntax-instr-control}{\mathsf{br\_on\_non\_null}}\)
New control instruction:
- \(\href{../syntax/instructions.html#syntax-instr-control}{\mathsf{call\_ref}}\)
Refined typing of reference instruction:
- \(\href{../syntax/instructions.html#syntax-instr-ref}{\mathsf{ref{.}func}}\) with more precise result type
Refined typing of local instructions and instruction sequences to track the initialization status of locals with non-defaultable type
Extended table definitions with optional initializer expression

Garbage Collection¶

Added managed reference types. [13]

New forms of heap types:
- \(\href{../syntax/types.html#syntax-heaptype}{\mathsf{any}}\)
- \(\href{../syntax/types.html#syntax-heaptype}{\mathsf{eq}}\)
- \(\href{../syntax/types.html#syntax-heaptype}{\mathsf{i\scriptstyle31}}\)
- \(\href{../syntax/types.html#syntax-heaptype}{\mathsf{struct}}\)
- \(\href{../syntax/types.html#syntax-heaptype}{\mathsf{array}}\)
- \(\href{../syntax/types.html#syntax-heaptype}{\mathsf{none}}\)
- \(\href{../syntax/types.html#syntax-heaptype}{\mathsf{nofunc}}\)
- \(\href{../syntax/types.html#syntax-heaptype}{\mathsf{noextern}}\)
New reference type short-hands:
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{anyref}}\)
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{eqref}}\)
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{i{\scriptstyle31}ref}}\)
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{structref}}\)
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{arrayref}}\)
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{nullref}}\)
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{nullfuncref}}\)
- \(\href{../syntax/types.html#syntax-reftype}{\mathsf{nullexternref}}\)
New forms of type definitions:
Enriched subtyping based on explicitly declared sub types and the new heap types
New generic reference instructions:
- \(\href{../syntax/instructions.html#syntax-instr-ref}{\mathsf{ref{.}eq}}\)
- \(\href{../syntax/instructions.html#syntax-instr-ref}{\mathsf{ref{.}test}}\)
- \(\href{../syntax/instructions.html#syntax-instr-ref}{\mathsf{ref{.}cast}}\)
- \(\href{../syntax/instructions.html#syntax-instr-control}{\mathsf{br\_on\_cast}}\)
- \(\href{../syntax/instructions.html#syntax-instr-control}{\mathsf{br\_on\_cast\_fail}}\)
New reference instructions for unboxed scalars:
- \(\href{../syntax/instructions.html#syntax-instr-i31}{\mathsf{ref{.}i\scriptstyle31}}\)
- \(\href{../syntax/instructions.html#syntax-instr-i31}{\mathsf{i{\scriptstyle31}{.}get}}\mathsf{\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
New reference instructions for structure types:
- \(\href{../syntax/instructions.html#syntax-instr-struct}{\mathsf{struct{.}new}}\)
- \(\href{../syntax/instructions.html#syntax-instr-struct}{\mathsf{struct{.}new\_default}}\)
- \(\href{../syntax/instructions.html#syntax-instr-struct}{\mathsf{struct{.}get}}\mathsf{\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}^?\)
- \(\href{../syntax/instructions.html#syntax-instr-struct}{\mathsf{struct{.}set}}\)
New reference instructions for array types:
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}new}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}new\_default}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}new\_fixed}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}new\_data}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}new\_elem}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}get}}\mathsf{\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}^?\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}set}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}len}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}fill}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}copy}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}init\_data}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}init\_elem}}\)
New reference instructions for converting external types:
- \(\href{../syntax/instructions.html#syntax-instr-extern}{\mathsf{any{.}convert\_extern}}\)
- \(\href{../syntax/instructions.html#syntax-instr-extern}{\mathsf{extern{.}convert\_any}}\)
Extended set of constant instructions with:
- \(\href{../syntax/instructions.html#syntax-instr-i31}{\mathsf{ref{.}i\scriptstyle31}}\)
- \(\href{../syntax/instructions.html#syntax-instr-struct}{\mathsf{struct{.}new}}\)
- \(\href{../syntax/instructions.html#syntax-instr-struct}{\mathsf{struct{.}new\_default}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}new}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}new\_default}}\)
- \(\href{../syntax/instructions.html#syntax-instr-array}{\mathsf{array{.}new\_fixed}}\)
- \(\href{../syntax/instructions.html#syntax-instr-extern}{\mathsf{any{.}convert\_extern}}\)
- \(\href{../syntax/instructions.html#syntax-instr-extern}{\mathsf{extern{.}convert\_any}}\)

Relaxed Vector Instructions¶

Added new relaxed vector instructions, whose behaviour is non-deterministic and implementation-dependent. [14]

New binary vector instruction:
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.relaxed\_min}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.relaxed\_max}\)
- \(\mathsf{i16x8.relaxed\_q15mulr\_s}\)
- \(\mathsf{i16x8.relaxed\_dot\_i8x16\_i7x16\_s}\)
New ternary vector instruction:
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.relaxed\_madd}\)
- \(\mathsf{f}\!N\!\mathsf{x}\!M\!\mathsf{.relaxed\_nmadd}\)
- \(\mathsf{i}\!N\!\mathsf{x}\!M\!\mathsf{.relaxed\_laneselect}\)
- \(\mathsf{i32x4.relaxed\_dot\_i8x16\_i7x16\_add\_s}\)
New conversion vector instructions:
- \(\mathsf{i32x4.relaxed\_trunc\_f32x4\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\)
- \(\mathsf{i32x4.relaxed\_trunc\_f64x2\_}\href{../syntax/instructions.html#syntax-sx}{\mathit{sx}}\mathsf{\_zero}\)
New byte reordering vector instruction:
- \(\mathsf{i8x16.relaxed\_swizzle}\)

Profiles¶

Introduced the concept of profile for specifying language subsets.

A new profile defining a deterministic mode of execution.

Custom Annotations¶

Added generic syntax for custom annotations in the text format, mirroring the role of custom sections in the binary format. [15]

Annotations of the form \(\def\mathdef89#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef89{(@id~\dots)}\) are allowed anywhere in the text format
Identifiers can be escaped as \(\def\mathdef90#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef90{@"\dots"}\) with arbitrary names
Defined name annotations \(\def\mathdef91#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef91{(@name~"\dots")}\) for:
Defined custom annotation \(\def\mathdef92#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef92{(@custom~"\dots")}\) to represent arbitrary custom sections in the text format