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<title>Instruction.InstructionAlias - ARM Machine Readable Schema - 2.6.3</title>
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<div class="col-md-6 pull-left"><h1>AARCHMRS Schema <small>2.6.3</small></h1></div>
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<h2>
<span class="title-namespace">Instruction.</span><span class=" title-type">InstructionAlias</span>
<!-- if oneOf is set, then type is ignored -->
<span class="type">object</span>
</h2>
<div class="static-markdown"><p>An <a class="schema_link" href="../Instruction/InstructionAlias_schema.html" title="Instruction.InstructionAlias">InstructionAlias</a> object defines an alias of an <a class="schema_link" href="../Instruction/Instruction_schema.html" title="Instruction.Instruction">Instruction</a> as a child of
that instruction. The alias assembly can be different, but the assembly it defines maps back to the assembly
of its parent <a class="schema_link" href="../Instruction/Instruction_schema.html" title="Instruction.Instruction">Instruction</a>.</p>
<p>The <code>operation_id</code> refers to an instance of <code>OperationAlias</code>, which provides a link to the ASL pseudocode
for the alias and overrides the descriptive elements.</p>
<p>The <code>preferred</code> attribute states when a disassembler should emit the alias instead of the parent instruction.
It is a condition that evaluates True when the alias
should be emitted and False when the parent instruction should be emitted.</p>
<p>The first example below is of an alias named 'ADC32'. Its assembly is never preferred.</p>
<p>The second example has a <code>preferred</code> attribute. Its assembly is preferred if and only if FEAT_ADC is implemented
(otherwise, its parent is the preferred disassembly).</p></div>
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<div>
<!-- A simple object -->
<h3 class="type">object</h3>
<table class="table table-hover properties">
<thead>
<tr>
<th class="col-md-4">Properties</th>
<th class="col-md-4">Type</th>
<th class="col-md-4">Description</th>
</tr>
</thead>
<tbody>
<!-- properties -->
<tr id="/properties/_meta" class="property">
<th class="col-md-4">
<a href="#/properties/_meta">_meta</a>
</th>
<td class="col-md-4">
<a href="../Meta_schema.html" class="schema_link">Meta</a>
</td>
<td class="col-md-4">
<div><p>Metadata</p></div>
<div>
See
<a href="../Meta_schema.html" class="schema_link">Meta</a>
for more information.
</div>
</td>
</tr>
<tr id="/properties/_type" class="property">
<th class="col-md-4">
<a href="#/properties/_type">_type</a>
</th>
<td class="col-md-4">
</td>
<td class="col-md-4">
<dl>
<dt>Enum</dt>
<dd>
<code>Instruction.InstructionAlias</code>
</dd>
</dl>
</td>
</tr>
<tr id="/properties/assembly" class="property">
<th class="col-md-4">
<a href="#/properties/assembly">assembly<sup>&loz;</sup></a>
</th>
<td class="col-md-4">
<a href="Assembly_schema.html" class="schema_link">Assembly</a>
</td>
<td class="col-md-4">
<div><p>The assembly for this <a class="schema_link" href="../Instruction/InstructionAlias_schema.html" title="Instruction.InstructionAlias">InstructionAlias</a>.</p></div>
<div>
See
<a href="Assembly_schema.html" class="schema_link">Assembly</a>
for more information.
</div>
</td>
</tr>
<tr id="/properties/condition" class="property">
<th class="col-md-4">
<a href="#/properties/condition">condition</a>
</th>
<td class="col-md-4">
<a href="../Traits/HasCondition_schema.html#/definitions/condition" class="schema_link">Traits.HasCondition</a>
</td>
<td class="col-md-4">
<div>
See
<a href="../Traits/HasCondition_schema.html#/definitions/condition" class="schema_link">definitions.condition</a> in
<a href="../Traits/HasCondition_schema.html#/definitions/condition" class="schema_link">Traits.HasCondition</a>
for more information.
</div>
</td>
</tr>
<tr id="/properties/name" class="property">
<th class="col-md-4">
<a href="#/properties/name">name<sup>&loz;</sup></a>
</th>
<td class="col-md-4">
<a href="../AST/Identifier_schema.html#/definitions/c_identifier_regex" class="schema_link">AST.Identifier</a>
</td>
<td class="col-md-4">
<div><p>The unique name of the <a class="schema_link" href="../Instruction/InstructionAlias_schema.html" title="Instruction.InstructionAlias">InstructionAlias</a>, which identifies it in the instruction set.</p></div>
<div>
See
<a href="../AST/Identifier_schema.html#/definitions/c_identifier_regex" class="schema_link">definitions.c_identifier_regex</a> in
<a href="../AST/Identifier_schema.html#/definitions/c_identifier_regex" class="schema_link">AST.Identifier</a>
for more information.
</div>
</td>
</tr>
<tr id="/properties/operation_id" class="property">
<th class="col-md-4">
<a href="#/properties/operation_id">operation_id<sup>&loz;</sup></a>
</th>
<td class="col-md-4">
<a href="../AST/Identifier_schema.html#/definitions/c_identifier_regex" class="schema_link">AST.Identifier</a>
</td>
<td class="col-md-4">
<div><p>The ID of the <a class="schema_link" href="../Instruction/OperationAlias_schema.html" title="Instruction.OperationAlias">OperationAlias</a> for this <a class="schema_link" href="../Instruction/InstructionAlias_schema.html" title="Instruction.InstructionAlias">InstructionAlias</a>. The <a class="schema_link" href="../Instruction/OperationAlias_schema.html" title="Instruction.OperationAlias">OperationAlias</a>
is a value in the <code>operations</code> property of the top-level <a class="schema_link" href="../Instruction/Instructions_schema.html" title="Instruction.Instructions">Instructions</a> element, and this <code>operation_id</code> matches its key.</p></div>
<div>
See
<a href="../AST/Identifier_schema.html#/definitions/c_identifier_regex" class="schema_link">definitions.c_identifier_regex</a> in
<a href="../AST/Identifier_schema.html#/definitions/c_identifier_regex" class="schema_link">AST.Identifier</a>
for more information.
</div>
</td>
</tr>
<tr id="/properties/preferred" class="property">
<th class="col-md-4">
<a href="#/properties/preferred">preferred</a>
</th>
<td class="col-md-4">
<a href="../Traits/HasCondition_schema.html#/definitions/condition" class="schema_link">Traits.HasCondition</a>
</td>
<td class="col-md-4">
<div><p>Defines whether this <a class="schema_link" href="../Instruction/InstructionAlias_schema.html" title="Instruction.InstructionAlias">InstructionAlias</a> is the preferred disassembly for the parent <a class="schema_link" href="../Instruction/Instruction_schema.html" title="Instruction.Instruction">Instruction</a>.
If the <code>preferred</code> condition evaluates True, this <a class="schema_link" href="../Instruction/InstructionAlias_schema.html" title="Instruction.InstructionAlias">InstructionAlias</a> is the preferred disassembly.
This can be a complex condition that needs to be evaluated.</p></div>
<div>
See
<a href="../Traits/HasCondition_schema.html#/definitions/condition" class="schema_link">definitions.condition</a> in
<a href="../Traits/HasCondition_schema.html#/definitions/condition" class="schema_link">Traits.HasCondition</a>
for more information.
</div>
<div>
<b>Default</b>
<pre class="schema-json"><code class="language-json">{
&#34;_type&#34;: &#34;AST.Bool&#34;,
&#34;value&#34;: false
}</code></pre>
</div>
</td>
</tr>
<!-- patternProperties -->
<!-- object property attributes -->
<tr>
<td colspan="3">
<dl>
<dt>Additional Properties</dt>
<dd>Not Allowed</dd>
</dl>
</td>
</tr>
<tr>
<td colspan="3">
<dl>
<dt>&loz; Required</dt>
<dd>Properties marked with &loz; are required properties.</dd>
</dl>
</td>
</tr>
</tbody>
</table>
<!-- array, and it has described items -->
</div>
<h5>Examples</h5>
<div>
<pre class="schema-json"><code class="language-json">{
&#34;_type&#34;: &#34;Instruction.InstructionAlias&#34;,
&#34;name&#34;: &#34;ADC32&#34;,
&#34;operation_id&#34;: &#34;foo&#34;,
&#34;assembly&#34;: {
&#34;_type&#34;: &#34;Instruction.Assembly&#34;,
&#34;symbols&#34;: [
{
&#34;_type&#34;: &#34;Instruction.Symbols.Literal&#34;,
&#34;value&#34;: &#34;ADD&#34;
},
{
&#34;_type&#34;: &#34;Instruction.Symbols.RuleReference&#34;,
&#34;rule_id&#34;: &#34;Rd&#34;
},
{
&#34;_type&#34;: &#34;Instruction.Symbols.RuleReference&#34;,
&#34;rule_id&#34;: &#34;imm4&#34;
}
]
}
}</code></pre>
<pre class="schema-json"><code class="language-json">{
&#34;_type&#34;: &#34;Instruction.InstructionAlias&#34;,
&#34;name&#34;: &#34;ADC32&#34;,
&#34;operation_id&#34;: &#34;foo&#34;,
&#34;assembly&#34;: {
&#34;_type&#34;: &#34;Instruction.Assembly&#34;,
&#34;symbols&#34;: [
{
&#34;_type&#34;: &#34;Instruction.Symbols.Literal&#34;,
&#34;value&#34;: &#34;ADD&#34;
},
{
&#34;_type&#34;: &#34;Instruction.Symbols.RuleReference&#34;,
&#34;rule_id&#34;: &#34;Rd&#34;
},
{
&#34;_type&#34;: &#34;Instruction.Symbols.RuleReference&#34;,
&#34;rule_id&#34;: &#34;imm4&#34;
}
]
},
&#34;preferred&#34;: {
&#34;_type&#34;: &#34;AST.Function&#34;,
&#34;arguments&#34;: [
{
&#34;_type&#34;: &#34;AST.Identifier&#34;,
&#34;value&#34;: &#34;FEAT_ADC&#34;
}
],
&#34;name&#34;: &#34;IsFeatureImplemented&#34;
}
}</code></pre>
</div>
</div>
<div class="row schema">
<h3>Schema <small><a href="http://json-schema.org/draft-04/schema#">http://json-schema.org/draft-04/schema#</a></small></h3>
<pre class="schema-json"><code class="language-json">{
"type": "object",
"info": [
[
"An $(~Instruction.InstructionAlias) object defines an alias of an $(~Instruction.Instruction) as a child of",
"that instruction. The alias assembly can be different, but the assembly it defines maps back to the assembly",
"of its parent $(~Instruction.Instruction)."
],
[
"The `operation_id` refers to an instance of `OperationAlias`, which provides a link to the ASL pseudocode",
"for the alias and overrides the descriptive elements."
],
[
"The `preferred` attribute states when a disassembler should emit the alias instead of the parent instruction.",
"It is a condition that evaluates True when the alias",
"should be emitted and False when the parent instruction should be emitted."
],
"The first example below is of an alias named 'ADC32'. Its assembly is never preferred.",
[
"The second example has a `preferred` attribute. Its assembly is preferred if and only if FEAT_ADC is implemented",
"(otherwise, its parent is the preferred disassembly)."
]
],
"examples": [
{
"_type": "Instruction.InstructionAlias",
"name": "ADC32",
"operation_id": "foo",
"assembly": {
"_type": "Instruction.Assembly",
"symbols": [
{
"_type": "Instruction.Symbols.Literal",
"value": "ADD"
},
{
"_type": "Instruction.Symbols.RuleReference",
"rule_id": "Rd"
},
{
"_type": "Instruction.Symbols.RuleReference",
"rule_id": "imm4"
}
]
}
},
{
"_type": "Instruction.InstructionAlias",
"name": "ADC32",
"operation_id": "foo",
"assembly": {
"_type": "Instruction.Assembly",
"symbols": [
{
"_type": "Instruction.Symbols.Literal",
"value": "ADD"
},
{
"_type": "Instruction.Symbols.RuleReference",
"rule_id": "Rd"
},
{
"_type": "Instruction.Symbols.RuleReference",
"rule_id": "imm4"
}
]
},
"preferred": {
"_type": "AST.Function",
"arguments": [
{
"_type": "AST.Identifier",
"value": "FEAT_ADC"
}
],
"name": "IsFeatureImplemented"
}
}
],
"properties": {
"_meta": {
"$ref": "../Meta.json",
"info": [
"Metadata"
]
},
"_type": {
"enum": [
"Instruction.InstructionAlias"
]
},
"name": {
"info": [
"The unique name of the $(~Instruction.InstructionAlias), which identifies it in the instruction set."
],
"$ref": "../AST/Identifier.json#/definitions/c_identifier_regex"
},
"operation_id": {
"info": [
[
"The ID of the $(~Instruction.OperationAlias) for this $(~Instruction.InstructionAlias). The $(~Instruction.OperationAlias)",
"is a value in the `operations` property of the top-level $(~Instruction.Instructions) element, and this `operation_id` matches its key."
]
],
"$ref": "../AST/Identifier.json#/definitions/c_identifier_regex"
},
"assembly": {
"info": [
"The assembly for this $(~Instruction.InstructionAlias)."
],
"$ref": "Assembly.json"
},
"preferred": {
"info": [
[
"Defines whether this $(~Instruction.InstructionAlias) is the preferred disassembly for the parent $(~Instruction.Instruction).",
"If the `preferred` condition evaluates True, this $(~Instruction.InstructionAlias) is the preferred disassembly.",
"This can be a complex condition that needs to be evaluated."
]
],
"$ref": "../Traits/HasCondition.json#/definitions/condition",
"default": {
"_type": "AST.Bool",
"value": false
}
},
"condition": {
"$ref": "../Traits/HasCondition.json#/definitions/condition"
}
},
"required": [
"name",
"operation_id",
"assembly"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-04/schema#",
"title": "Instruction.InstructionAlias"
}</code></pre>
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