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[spec] Runtime format of element and data segments
This is copied and modified from this closed PR: #19
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‎document/core/exec/modules.rst

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@@ -371,6 +371,64 @@ New instances of :ref:`functions <syntax-funcinst>`, :ref:`tables <syntax-tablei
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\end{array}
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.. index:: element, element instance, element address
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.. _alloc-elem:
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:ref:`Element segments <syntax-eleminst>`
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.........................................
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1. Let :math:`\elem` be the :ref:`element segment <syntax-elem>` to allocate.
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2. Let :math:`\{ \EINIT~\elemexpr^\ast, \dots \}` be the structure of :ref:`element segment <syntax-elem>` :math:`\elem`.
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3. Let :math:`a` be the first free :ref:`element address <syntax-elemaddr>` in :math:`S`.
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5. Let :math:`\eleminst` be the :ref:`element instance <syntax-eleminst>` :math:`\{ \EIINIT~\elemexpr^\ast \}`.
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6. Append :math:`\eleminst` to the |SELEM| of :math:`S`.
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7. Return :math:`a`.
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.. math::
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\begin{array}{rlll}
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\allocelem(S, \elem) &=& S', \elemaddr \\[1ex]
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\mbox{where:} \hfill \\
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\elem &=& \{ \EINIT~\elemexpr^\ast, \dots \} \\
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\elemaddr &=& |S.\SELEM| \\
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\eleminst &=& \{ \EIINIT~\elemexpr^\ast \} \\
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S' &=& S \compose \{\SELEM~\eleminst\} \\
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\end{array}
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.. index:: data, data instance, data address
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.. _alloc-data:
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:ref:`Data segments <syntax-datainst>`
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......................................
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1. Let :math:`\data` be the :ref:`data segment <syntax-data>` to allocate.
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2. Let :math:`\{ \DINIT~\bytes, \dots \}` be the structure of :ref:`data segment <syntax-data>` :math:`\data`.
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2. Let :math:`a` be the first free :ref:`data address <syntax-dataaddr>` in :math:`S`.
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3. Let :math:`\datainst` be the :ref:`data instance <syntax-datainst>` :math:`\{ \DIINIT~\bytes \}`.
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4. Append :math:`\datainst` to the |SDATA| of :math:`S`.
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5. Return :math:`a`.
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.. math::
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\begin{array}{rlll}
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\allocdata(S, \data) &=& S', \dataaddr \\[1ex]
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\mbox{where:} \hfill \\
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\data &=& \{ \DINIT~\bytes, \dots \} \\
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\dataaddr &=& |S.\SDATA| \\
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\datainst &=& \{ \DIINIT~d.\DINIT \} \\
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S' &=& S \compose \{\SDATA~\datainst\} \\
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\end{array}
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.. index:: table, table instance, table address, grow, limits
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.. _grow-table:
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‎document/core/exec/runtime.rst

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@@ -60,7 +60,7 @@ Store
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~~~~~
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The *store* represents all global state that can be manipulated by WebAssembly programs.
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It consists of the runtime representation of all *instances* of :ref:`functions <syntax-funcinst>`, :ref:`tables <syntax-tableinst>`, :ref:`memories <syntax-meminst>`, and :ref:`globals <syntax-globalinst>` that have been :ref:`allocated <alloc>` during the life time of the abstract machine. [#gc]_
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It consists of the runtime representation of all *instances* of :ref:`functions <syntax-funcinst>`, :ref:`tables <syntax-tableinst>`, :ref:`memories <syntax-meminst>`, and :ref:`globals <syntax-globalinst>`, :ref:`element segments <syntax-eleminst>`, and :ref:`data segments <syntax-datainst>` that have been :ref:`allocated <alloc>` during the life time of the abstract machine. [#gc]_
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Syntactically, the store is defined as a :ref:`record <notation-record>` listing the existing instances of each category:
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@@ -71,7 +71,9 @@ Syntactically, the store is defined as a :ref:`record <notation-record>` listing
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\SFUNCS & \funcinst^\ast, \\
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\STABLES & \tableinst^\ast, \\
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\SMEMS & \meminst^\ast, \\
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\SGLOBALS & \globalinst^\ast ~\} \\
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\SGLOBALS & \globalinst^\ast, \\
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\SELEM & (\eleminst^?)^\ast, \\
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\SDATA & (\datainst^?)^\ast ~\} \\
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\end{array}
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\end{array}
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@@ -87,25 +89,31 @@ Convention
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* The meta variable :math:`S` ranges over stores where clear from context.
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.. index:: ! address, store, function instance, table instance, memory instance, global instance, embedder
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.. index:: ! address, store, function instance, table instance, memory instance, global instance, element instance, data instance, embedder
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pair: abstract syntax; function address
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pair: abstract syntax; table address
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pair: abstract syntax; memory address
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pair: abstract syntax; global address
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pair: abstract syntax; element address
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pair: abstract syntax; data address
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pair: function; address
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pair: table; address
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pair: memory; address
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pair: global; address
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pair: element; address
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pair: data; address
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.. _syntax-funcaddr:
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.. _syntax-tableaddr:
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.. _syntax-memaddr:
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.. _syntax-globaladdr:
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.. _syntax-elemaddr:
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.. _syntax-dataaddr:
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.. _syntax-addr:
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Addresses
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~~~~~~~~~
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:ref:`Function instances <syntax-funcinst>`, :ref:`table instances <syntax-tableinst>`, :ref:`memory instances <syntax-meminst>`, and :ref:`global instances <syntax-globalinst>` in the :ref:`store <syntax-store>` are referenced with abstract *addresses*.
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:ref:`Function instances <syntax-funcinst>`, :ref:`table instances <syntax-tableinst>`, :ref:`memory instances <syntax-meminst>`, and :ref:`global instances <syntax-globalinst>`, :ref:`element instances <syntax-eleminst>`, and :ref:`data instances <syntax-datainst>` in the :ref:`store <syntax-store>` are referenced with abstract *addresses*.
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These are simply indices into the respective store component.
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.. math::
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\addr \\
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\production{(global address)} & \globaladdr &::=&
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\addr \\
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\production{(element address)} & \elemaddr &::=&
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\addr \\
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\production{(data address)} & \dataaddr &::=&
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\addr \\
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\end{array}
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An :ref:`embedder <embedder>` may assign identity to :ref:`exported <syntax-export>` store objects corresponding to their addresses,
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hence logical addresses can be arbitrarily large natural numbers.
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.. index:: ! instance, function type, function instance, table instance, memory instance, global instance, export instance, table address, memory address, global address, index, name
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.. index:: ! instance, function type, function instance, table instance, memory instance, global instance, element instance, data instance, export instance, table address, memory address, global address, element address, data address, index, name
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pair: abstract syntax; module instance
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pair: module; instance
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.. _syntax-moduleinst:
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\MITABLES & \tableaddr^\ast, \\
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\MIMEMS & \memaddr^\ast, \\
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\MIGLOBALS & \globaladdr^\ast, \\
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\MIELEMS & (\elemaddr^?)^\ast, \\
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\MIDATAS & (\dataaddr^?)^\ast, \\
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\MIEXPORTS & \exportinst^\ast ~\} \\
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\end{array}
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\end{array}
@@ -275,6 +289,42 @@ It holds an individual :ref:`value <syntax-val>` and a flag indicating whether i
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The value of mutable globals can be mutated through :ref:`variable instructions <syntax-instr-variable>` or by external means provided by the :ref:`embedder <embedder>`.
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.. index:: ! element instance, element segment, embedder, element expression
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pair: abstract syntax; element instance
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pair: element; instance
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.. _syntax-eleminst:
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Element Instances
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~~~~~~~~~~~~~~~~~
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An *element instance* is the runtime representation of an :ref:`element segment <syntax-elem>`.
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It holds a vector of :ref:`element expressions <syntax-elemexpr>`.
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.. math::
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\begin{array}{llll}
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\production{(element instance)} & \eleminst &::=&
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\{ \EIINIT~\vec(\elemexpr) \} \\
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\end{array}
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.. index:: ! data instance, data segment, embedder, byte
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pair: abstract syntax; data instance
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pair: data; instance
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.. _syntax-datainst:
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Data Instances
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~~~~~~~~~~~~~~
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An *data instance* is the runtime representation of a :ref:`data segment <syntax-data>`.
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It holds a vector of :ref:`bytes <syntax-byte>`.
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.. math::
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\begin{array}{llll}
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\production{(data instance)} & \datainst &::=&
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\{ \DIINIT~\vec(\byte) \} \\
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\end{array}
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.. index:: ! export instance, export, name, external value
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pair: abstract syntax; export instance
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pair: export; instance

‎document/core/util/macros.def

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@@ -806,6 +806,8 @@
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.. |alloctable| mathdef:: \xref{exec/modules}{alloc-table}{\F{alloctable}}
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.. |allocmem| mathdef:: \xref{exec/modules}{alloc-mem}{\F{allocmem}}
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.. |allocglobal| mathdef:: \xref{exec/modules}{alloc-global}{\F{allocglobal}}
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.. |allocelem| mathdef:: \xref{exec/modules}{alloc-elem}{\F{allocelem}}
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.. |allocdata| mathdef:: \xref{exec/modules}{alloc-data}{\F{allocdata}}
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.. |allocmodule| mathdef:: \xref{exec/modules}{alloc-module}{\F{allocmodule}}
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.. |growtable| mathdef:: \xref{exec/modules}{grow-table}{\F{growtable}}
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.. |tableaddr| mathdef:: \xref{exec/runtime}{syntax-tableaddr}{\X{tableaddr}}
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.. |memaddr| mathdef:: \xref{exec/runtime}{syntax-memaddr}{\X{memaddr}}
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.. |globaladdr| mathdef:: \xref{exec/runtime}{syntax-globaladdr}{\X{globaladdr}}
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.. |elemaddr| mathdef:: \xref{exec/runtime}{syntax-elemaddr}{\X{elemaddr}}
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.. |dataaddr| mathdef:: \xref{exec/runtime}{syntax-dataaddr}{\X{dataaddr}}
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.. Instances, terminals
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.. |GIVALUE| mathdef:: \xref{exec/runtime}{syntax-globalinst}{\K{value}}
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.. |GIMUT| mathdef:: \xref{exec/runtime}{syntax-globalinst}{\K{mut}}
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.. |EIINIT| mathdef:: \xref{exec/runtime}{syntax-eleminst}{\K{init}}
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.. |DIINIT| mathdef:: \xref{exec/runtime}{syntax-datainst}{\K{init}}
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.. |EINAME| mathdef:: \xref{exec/runtime}{syntax-exportinst}{\K{name}}
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.. |EIVALUE| mathdef:: \xref{exec/runtime}{syntax-exportinst}{\K{value}}
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.. |MITABLES| mathdef:: \xref{exec/runtime}{syntax-moduleinst}{\K{tableaddrs}}
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.. |MIMEMS| mathdef:: \xref{exec/runtime}{syntax-moduleinst}{\K{memaddrs}}
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.. |MIGLOBALS| mathdef:: \xref{exec/runtime}{syntax-moduleinst}{\K{globaladdrs}}
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.. |MIELEMS| mathdef:: \xref{exec/runtime}{syntax-moduleinst}{\K{elemaddrs}}
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.. |MIDATAS| mathdef:: \xref{exec/runtime}{syntax-moduleinst}{\K{dataaddrs}}
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.. |MIEXPORTS| mathdef:: \xref{exec/runtime}{syntax-moduleinst}{\K{exports}}
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.. |funcelem| mathdef:: \xref{exec/runtime}{syntax-funcelem}{\X{funcelem}}
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.. |meminst| mathdef:: \xref{exec/runtime}{syntax-meminst}{\X{meminst}}
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.. |globalinst| mathdef:: \xref{exec/runtime}{syntax-globalinst}{\X{globalinst}}
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.. |eleminst| mathdef:: \xref{exec/runtime}{syntax-eleminst}{\X{eleminst}}
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.. |datainst| mathdef:: \xref{exec/runtime}{syntax-datainst}{\X{datainst}}
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.. |exportinst| mathdef:: \xref{exec/runtime}{syntax-exportinst}{\X{exportinst}}
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.. |hostfunc| mathdef:: \xref{exec/runtime}{syntax-hostfunc}{\X{hostfunc}}
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.. |STABLES| mathdef:: \xref{exec/runtime}{syntax-store}{\K{tables}}
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.. |SMEMS| mathdef:: \xref{exec/runtime}{syntax-store}{\K{mems}}
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.. |SGLOBALS| mathdef:: \xref{exec/runtime}{syntax-store}{\K{globals}}
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.. |SELEM| mathdef:: \xref{exec/runtime}{syntax-store}{\K{elem}}
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.. |SDATA| mathdef:: \xref{exec/runtime}{syntax-store}{\K{data}}
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.. Store, non-terminals
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