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@ -9,42 +9,44 @@
<div class="doc_title">TableGen Fundamentals</div> <div class="doc_title">TableGen Fundamentals</div>
<div class="doc_text">
<ul> <ul>
<li><a href="#introduction">Introduction</a></li> <li><a href="#introduction">Introduction</a>
<ol> <ol>
<li><a href="#concepts">Basic concepts</a></li> <li><a href="#concepts">Basic concepts</a></li>
<li><a href="#example">An example record</a></li> <li><a href="#example">An example record</a></li>
<li><a href="#running">Running TableGen</a></li> <li><a href="#running">Running TableGen</a></li>
</ol> </ol></li>
<li><a href="#syntax">TableGen syntax</a></li> <li><a href="#syntax">TableGen syntax</a>
<ol> <ol>
<li><a href="#primitives">TableGen primitives</a></li> <li><a href="#primitives">TableGen primitives</a>
<ol> <ol>
<li><a href="#comments">TableGen comments</a></li> <li><a href="#comments">TableGen comments</a></li>
<li><a href="#types">The TableGen type system</a></li> <li><a href="#types">The TableGen type system</a></li>
<li><a href="#values">TableGen values and expressions</a></li> <li><a href="#values">TableGen values and expressions</a></li>
</ol> </ol></li>
<li><a href="#classesdefs">Classes and definitions</a></li> <li><a href="#classesdefs">Classes and definitions</a>
<ol> <ol>
<li><a href="#valuedef">Value definitions</a></li> <li><a href="#valuedef">Value definitions</a></li>
<li><a href="#recordlet">'let' expressions</a></li> <li><a href="#recordlet">'let' expressions</a></li>
<li><a href="#templateargs">Class template arguments</a></li> <li><a href="#templateargs">Class template arguments</a></li>
</ol> </ol></li>
<li><a href="#filescope">File scope entities</a></li> <li><a href="#filescope">File scope entities</a>
<ol> <ol>
<li><a href="#include">File inclusion</a></li> <li><a href="#include">File inclusion</a></li>
<li><a href="#globallet">'let' expressions</a></li> <li><a href="#globallet">'let' expressions</a></li>
</ol> </ol></li>
</ol> </ol></li>
<li><a href="#backends">TableGen backends</a></li> <li><a href="#backends">TableGen backends</a>
<ol> <ol>
<li><a href="#">todo</a></li> <li><a href="#">todo</a></li>
</ol> </ol></li>
<li><a href="#codegenerator">The LLVM code generator</a></li> <li><a href="#codegenerator">The LLVM code generator</a>
<ol> <ol>
<li><a href="#">todo</a></li> <li><a href="#">todo</a></li>
</ol> </ol></li>
</ul> </ul>
</div>
<!-- *********************************************************************** --> <!-- *********************************************************************** -->
<div class="doc_section"><a name="introduction">Introduction</a></div> <div class="doc_section"><a name="introduction">Introduction</a></div>
@ -62,72 +64,56 @@ makes it easier to structure domain specific information.</p>
<p>The core part of TableGen <a href="#syntax">parses a file</a>, instantiates <p>The core part of TableGen <a href="#syntax">parses a file</a>, instantiates
the declarations, and hands the result off to a domain-specific "<a the declarations, and hands the result off to a domain-specific "<a
href="#backends">TableGen backend</a>" for processing. The current major user href="#backends">TableGen backend</a>" for processing. The current major user
of TableGen is the <a href="#codegenerator">LLVM code generator</a>. of TableGen is the <a href="#codegenerator">LLVM code generator</a>.</p>
</p>
<p> <p>Note that if you work on TableGen much, and use emacs or vim, that you can
Note that if you work on TableGen much, and use emacs or vim, that you can find find an emacs "TableGen mode" and a vim language file in
an emacs "TableGen mode" and a vim language file in <tt>llvm/utils/emacs</tt> <tt>llvm/utils/emacs</tt> and <tt>llvm/utils/vim</tt> directory of your LLVM
and <tt>llvm/utils/vim</tt> directory of your LLVM distribution, respectively. distribution, respectively.</p>
</p>
</div> </div>
<!-- ======================================================================= --> <!-- ======================================================================= -->
<div class="doc_subsection"> <div class="doc_subsection"><a name="running">Basic concepts</a></div>
<a name="running">Basic concepts</a>
</div>
<div class="doc_text"> <div class="doc_text">
<p> <p>TableGen files consist of two key parts: 'classes' and 'definitions', both
TableGen files consist of two key parts: 'classes' and 'definitions', both of of which are considered 'records'.</p>
which are considered 'records'.
</p>
<p> <p><b>TableGen records</b> have a unique name, a list of values, and a list of
<b>TableGen records</b> have a unique name, a list of values, and a list of
superclasses. The list of values is main data that TableGen builds for each superclasses. The list of values is main data that TableGen builds for each
record, it is this that holds the domain specific information for the record, it is this that holds the domain specific information for the
application. The interpretation of this data is left to a specific <a application. The interpretation of this data is left to a specific <a
href="#backends">TableGen backend</a>, but the structure and format rules are href="#backends">TableGen backend</a>, but the structure and format rules are
taken care of and fixed by TableGen. taken care of and fixed by TableGen.</p>
</p>
<p> <p><b>TableGen definitions</b> are the concrete form of 'records'. These
<b>TableGen definitions</b> are the concrete form of 'records'. These generally generally do not have any undefined values, and are marked with the
do not have any undefined values, and are marked with the '<tt>def</tt>' '<tt>def</tt>' keyword.</p>
keyword.
</p>
<p> <p><b>TableGen classes</b> are abstract records that are used to build and
<b>TableGen classes</b> are abstract records that are used to build and describe describe other records. These 'classes' allow the end-user to build
other records. These 'classes' allow the end-user to build abstractions for abstractions for either the domain they are targetting (such as "Register",
either the domain they are targetting (such as "Register", "RegisterClass", and "RegisterClass", and "Instruction" in the LLVM code generator) or for the
"Instruction" in the LLVM code generator) or for the implementor to help factor implementor to help factor out common properties of records (such as "FPInst",
out common properties of records (such as "FPInst", which is used to represent which is used to represent floating point instructions in the X86 backend).
floating point instructions in the X86 backend). TableGen keeps track of all of TableGen keeps track of all of the classes that are used to build up a
the classes that are used to build up a definition, so the backend can find all definition, so the backend can find all definitions of a particular class, such
definitions of a particular class, such as "Instruction". as "Instruction".</p>
</p>
</div> </div>
<!-- ======================================================================= --> <!-- ======================================================================= -->
<div class="doc_subsection"> <div class="doc_subsection"><a name="example">An example record</a></div>
<a name="example">An example record</a>
</div>
<div class="doc_text"> <div class="doc_text">
<p> <p>With no other arguments, TableGen parses the specified file and prints out
With no other arguments, TableGen parses the specified file and prints out all all of the classes, then all of the definitions. This is a good way to see what
of the classes, then all of the definitions. This is a good way to see what the the various definitions expand to fully. Running this on the <tt>X86.td</tt>
various definitions expand to fully. Running this on the <tt>X86.td</tt> file file prints this (at the time of this writing):</p>
prints this (at the time of this writing):
</p>
<p>
<pre> <pre>
... ...
<b>def</b> ADDrr8 { <i>// Instruction X86Inst I2A8 Pattern</i> <b>def</b> ADDrr8 { <i>// Instruction X86Inst I2A8 Pattern</i>
@ -153,64 +139,53 @@ prints this (at the time of this writing):
<b>bits</b>&lt;3&gt; FPFormBits = { 0, 0, 0 }; <b>bits</b>&lt;3&gt; FPFormBits = { 0, 0, 0 };
} }
... ...
</pre><p> </pre>
<p> <p>This definition corresponds to an 8-bit register-register add instruction in
This definition corresponds to an 8-bit register-register add instruction in the the X86. The string after the '<tt>def</tt>' string indicates the name of the
X86. The string after the '<tt>def</tt>' string indicates the name of the
record ("<tt>ADDrr8</tt>" in this case), and the comment at the end of the line record ("<tt>ADDrr8</tt>" in this case), and the comment at the end of the line
indicates the superclasses of the definition. The body of the record contains indicates the superclasses of the definition. The body of the record contains
all of the data that TableGen assembled for the record, indicating that the all of the data that TableGen assembled for the record, indicating that the
instruction is part of the "X86" namespace, should be printed as "<tt>add</tt>" instruction is part of the "X86" namespace, should be printed as "<tt>add</tt>"
in the assembly file, it is a two-address instruction, has a particular in the assembly file, it is a two-address instruction, has a particular
encoding, etc. The contents and semantics of the information in the record is encoding, etc. The contents and semantics of the information in the record is
specific to the needs of the X86 backend, and is only shown as an example. specific to the needs of the X86 backend, and is only shown as an example.</p>
</p>
<p> <p>As you can see, a lot of information is needed for every instruction
As you can see, a lot of information is needed for every instruction supported supported by the code generator, and specifying it all manually would be
by the code generator, and specifying it all manually would be unmaintainble, unmaintainble, prone to bugs, and tiring to do in the first place. Because we
prone to bugs, and tiring to do in the first place. Because we are using are using TableGen, all of the information was derived from the following
TableGen, all of the information was derived from the following definition: definition:</p>
</p>
<p><pre> <pre>
<b>def</b> ADDrr8 : I2A8&lt;"add", 0x00, MRMDestReg&gt;, <b>def</b> ADDrr8 : I2A8&lt;"add", 0x00, MRMDestReg&gt;,
Pattern&lt;(set R8, (plus R8, R8))&gt;; Pattern&lt;(set R8, (plus R8, R8))&gt;;
</pre></p> </pre>
<p> <p>This definition makes use of the custom I2A8 (two address instruction with
This definition makes use of the custom I2A8 (two address instruction with 8-bit 8-bit operand) class, which is defined in the X86-specific TableGen file to
operand) class, which is defined in the X86-specific TableGen file to factor out factor out the common features that instructions of its class share. A key
the common features that instructions of its class share. A key feature of feature of TableGen is that it allows the end-user to define the abstractions
TableGen is that it allows the end-user to define the abstractions they prefer they prefer to use when describing their information.</p>
to use when describing their information.
</p>
</div> </div>
<!-- ======================================================================= --> <!-- ======================================================================= -->
<div class="doc_subsection"> <div class="doc_subsection"><a name="running">Running TableGen</a></div>
<a name="running">Running TableGen</a>
</div>
<div class="doc_text"> <div class="doc_text">
<p> <p>TableGen runs just like any other LLVM tool. The first (optional) argument
TableGen runs just like any other LLVM tool. The first (optional) argument
specifies the file to read. If a filename is not specified, <tt>tblgen</tt> specifies the file to read. If a filename is not specified, <tt>tblgen</tt>
reads from standard input. reads from standard input.</p>
</p>
<p> <p>To be useful, one of the <a href="#backends">TableGen backends</a> must be
To be useful, one of the <a href="#backends">TableGen backends</a> must be used. used. These backends are selectable on the command line (type '<tt>tblgen
These backends are selectable on the command line (type '<tt>tblgen --help</tt>' --help</tt>' for a list). For example, to get a list of all of the definitions
for a list). For example, to get a list of all of the definitions that subclass that subclass a particular type (which can be useful for building up an enum
a particular type (which can be useful for building up an enum list of these list of these records), use the <tt>--print-enums</tt> option:</p>
records), use the <tt>--print-enums</tt> option:
</p>
<p><pre> <pre>
$ tblgen X86.td -print-enums -class=Register $ tblgen X86.td -print-enums -class=Register
AH, AL, AX, BH, BL, BP, BX, CH, CL, CX, DH, DI, DL, DX, AH, AL, AX, BH, BL, BP, BX, CH, CL, CX, DH, DI, DL, DX,
EAX, EBP, EBX, ECX, EDI, EDX, ESI, ESP, FP0, FP1, FP2, FP3, FP4, FP5, FP6, EAX, EBP, EBX, ECX, EDI, EDX, ESI, ESP, FP0, FP1, FP2, FP3, FP4, FP5, FP6,
@ -220,18 +195,14 @@ $ tblgen X86.td -print-enums -class=Instruction
ADCrr32, ADDri16, ADDri16b, ADDri32, ADDri32b, ADDri8, ADDrr16, ADDrr32, ADCrr32, ADDri16, ADDri16b, ADDri32, ADDri32b, ADDri8, ADDrr16, ADDrr32,
ADDrr8, ADJCALLSTACKDOWN, ADJCALLSTACKUP, ANDri16, ANDri16b, ANDri32, ANDri32b, ADDrr8, ADJCALLSTACKDOWN, ADJCALLSTACKUP, ANDri16, ANDri16b, ANDri32, ANDri32b,
ANDri8, ANDrr16, ANDrr32, ANDrr8, BSWAPr32, CALLm32, CALLpcrel32, ... ANDri8, ANDrr16, ANDrr32, ANDrr8, BSWAPr32, CALLm32, CALLpcrel32, ...
</pre></p> </pre>
<p> <p>The default backend prints out all of the records, as described <a
The default backend prints out all of the records, as described <a href="#example">above</a>.</p>
href="#example">above</a>.
</p>
<p> <p>If you plan to use TableGen for some purpose, you will most likely have to
If you plan to use TableGen for some purpose, you will most likely have to <a <a href="#backends">write a backend</a> that extracts the information specific
href="#backends">write a backend</a> that extracts the information specific to to what you need and formats it in the appropriate way.</p>
what you need and formats it in the appropriate way.
</p>
</div> </div>
@ -241,54 +212,39 @@ what you need and formats it in the appropriate way.
<!-- *********************************************************************** --> <!-- *********************************************************************** -->
<div class="doc_text"> <div class="doc_text">
<p>TableGen doesn't care about the meaning of data (that is up to the backend
<p> to define), but it does care about syntax, and it enforces a simple type system.
TableGen doesn't care about the meaning of data (that is up to the backend to
define), but it does care about syntax, and it enforces a simple type system.
This section describes the syntax and the constructs allowed in a TableGen file. This section describes the syntax and the constructs allowed in a TableGen file.
</p> </p>
</div> </div>
<!-- ======================================================================= --> <!-- ======================================================================= -->
<div class="doc_subsection"> <div class="doc_subsection"><a name="primitives">TableGen primitives</a></div>
<a name="primitives">TableGen primitives</tt></a>
</div>
<!-----------------------------------------------------------------------------> <!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection"> <div class="doc_subsubsection"><a name="comments">TableGen comments</a></div>
<a name="comments">TableGen comments</tt></a>
</div>
<div class="doc_text"> <div class="doc_text">
<p>TableGen supports BCPL style "<tt>//</tt>" comments, which run to the end of <p>TableGen supports BCPL style "<tt>//</tt>" comments, which run to the end of
the line, and it also supports <b>nestable</b> "<tt>/* */</tt>" comments.</p> the line, and it also supports <b>nestable</b> "<tt>/* */</tt>" comments.</p>
</div> </div>
<!-- -------------------------------------------------------------------------->
<!-----------------------------------------------------------------------------> <div class="doc_subsubsection"><a name="types">The TableGen type system</a>
<div class="doc_subsubsection">
<a name="types">The TableGen type system</tt></a>
</div> </div>
<div class="doc_text"> <div class="doc_text">
<p> <p>TableGen files are strongly typed, in a simple (but complete) type-system.
TableGen files are strongly typed, in a simple (but complete) type-system.
These types are used to perform automatic conversions, check for errors, and to These types are used to perform automatic conversions, check for errors, and to
help interface designers constrain the input that they allow. Every <a help interface designers constrain the input that they allow. Every <a
href="#valuedef">value definition</a> is required to have an associated type. href="#valuedef">value definition</a> is required to have an associated type.
</p> </p>
<p> <p>TableGen supports a mixture of very low-level types (such as <tt>bit</tt>)
TableGen supports a mixture of very low-level types (such as <tt>bit</tt>) and and very high-level types (such as <tt>dag</tt>). This flexibility is what
very high-level types (such as <tt>dag</tt>). This flexibility is what allows allows it to describe a wide range of information conveniently and compactly.
it to describe a wide range of information conveniently and compactly. The The TableGen types are:</p>
TableGen types are:
</p>
<p>
<ul> <ul>
<li>"<tt><b>bit</b></tt>" - A 'bit' is a boolean value that can hold either 0 or <li>"<tt><b>bit</b></tt>" - A 'bit' is a boolean value that can hold either 0 or
1.</li> 1.</li>
@ -319,29 +275,25 @@ remember why this is distinct from string!</li>
<li>"<tt><b>dag</b></tt>" - This type represents a nestable directed graph of <li>"<tt><b>dag</b></tt>" - This type represents a nestable directed graph of
elements.</li> elements.</li>
</ul> </ul>
</p>
<p> <p>To date, these types have been sufficient for describing things that
To date, these types have been sufficient for describing things that TableGen TableGen has been used for, but it is straight-forward to extend this list if
has been used for, but it is straight-forward to extend this list if needed. needed.</p>
</p>
</div> </div>
<!-----------------------------------------------------------------------------> <!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection"> <div class="doc_subsubsection">
<a name="values">TableGen values and expressions</tt></a> <a name="values">TableGen values and expressions</a>
</div> </div>
<div> <div>
<p> <p>TableGen allows for a pretty reasonable number of different expression forms
TableGen allows for a pretty reasonable number of different expression forms
when building up values. These forms allow the TableGen file to be written in a when building up values. These forms allow the TableGen file to be written in a
natural syntax and flavor for the application. The current expression forms natural syntax and flavor for the application. The current expression forms
supported include: supported include:</p>
</p>
<p><ul> <ul>
<li>? - Uninitialized field.</li> <li>? - Uninitialized field.</li>
<li>0b1001011 - Binary integer value.</li> <li>0b1001011 - Binary integer value.</li>
<li>07654321 - Octal integer value (indicated by a leading 0).</li> <li>07654321 - Octal integer value (indicated by a leading 0).</li>
@ -360,27 +312,20 @@ supported include:
definition, the remaining elements in the list may be arbitrary other values, definition, the remaining elements in the list may be arbitrary other values,
including nested 'dag' values.</li> including nested 'dag' values.</li>
</ul></p> </ul>
<p> <p>Note that all of the values have rules specifying how they convert to values
Note that all of the values have rules specifying how they convert to values
for different types. These rules allow you to assign a value like "7" to a for different types. These rules allow you to assign a value like "7" to a
"bits&lt;4&gt;" value, for example. "bits&lt;4&gt;" value, for example.</p>
</p>
</div> </div>
<!-- ======================================================================= --> <!-- ======================================================================= -->
<div class="doc_subsection"> <div class="doc_subsection"><a name="classesdefs">Classes and definitions</a>
<a name="classesdefs">Classes and definitions</tt></a>
</div> </div>
<div> <div>
<p> <p>As mentioned in the <a href="#concepts">intro</a>, classes and definitions
As mentioned in the <a href="#concepts">intro</a>, classes and definitions
(collectively known as 'records') in TableGen are the main high-level unit of (collectively known as 'records') in TableGen are the main high-level unit of
information that TableGen collects. Records are defined with a <tt>def</tt> or information that TableGen collects. Records are defined with a <tt>def</tt> or
<tt>class</tt> keyword, the record name, and an optional list of "<a <tt>class</tt> keyword, the record name, and an optional list of "<a
@ -389,87 +334,78 @@ they are specified as a comma seperated list that starts with a colon character
(":"). If <a href="#valuedef">value definitions</a> or <a href="#recordlet">let (":"). If <a href="#valuedef">value definitions</a> or <a href="#recordlet">let
expressions</a> are needed for the class, they are enclosed in curly braces expressions</a> are needed for the class, they are enclosed in curly braces
("{}"); otherwise, the record ends with a semicolon. Here is a simple TableGen ("{}"); otherwise, the record ends with a semicolon. Here is a simple TableGen
file: file:</p>
</p>
<p><pre> <pre>
<b>class</b> C { <b>bit</b> V = 1; } <b>class</b> C { <b>bit</b> V = 1; }
<b>def</b> X : C; <b>def</b> X : C;
<b>def</b> Y : C { <b>def</b> Y : C {
<b>string</b> Greeting = "hello"; <b>string</b> Greeting = "hello";
} }
</pre></p> </pre>
<p> <p>This example defines two definitions, <tt>X</tt> and <tt>Y</tt>, both of
This example defines two definitions, <tt>X</tt> and <tt>Y</tt>, both of which which derive from the <tt>C</tt> class. Because of this, they both get the
derive from the <tt>C</tt> class. Because of this, they both get the <tt>V</tt> <tt>V</tt> bit value. The <tt>Y</tt> definition also gets the Greeting member
bit value. The <tt>Y</tt> definition also gets the Greeting member as well. as well.</p>
</p>
<p> <p>In general, classes are useful for collecting together the commonality
In general, classes are useful for collecting together the commonality between a between a group of records and isolating it in a single place. Also, classes
group of records and isolating it in a single place. Also, classes permit the permit the specification of default values for their subclasses, allowing the
specification of default values for their subclasses, allowing the subclasses to subclasses to override them as they wish.</p>
override them as they wish.
</p>
</div> </div>
<!-----------------------------------------------------------------------------> <!---------------------------------------------------------------------------->
<div class="doc_subsubsection"> <div class="doc_subsubsection">
<a name="valuedef">Value definitions</tt></a> <a name="valuedef">Value definitions</a>
</div> </div>
<div class="doc_text"> <div class="doc_text">
<p> <p>Value definitions define named entries in records. A value must be defined
Value definitions define named entries in records. A value must be defined
before it can be referred to as the operand for another value definition or before it can be referred to as the operand for another value definition or
before the value is reset with a <a href="#recordlet">let expression</a>. A before the value is reset with a <a href="#recordlet">let expression</a>. A
value is defined by specifying a <a href="#types">TableGen type</a> and a name. value is defined by specifying a <a href="#types">TableGen type</a> and a name.
If an initial value is available, it may be specified after the type with an If an initial value is available, it may be specified after the type with an
equal sign. Value definitions require terminating semicolons. equal sign. Value definitions require terminating semicolons.</p>
</div> </div>
<!-----------------------------------------------------------------------------> <!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection"> <div class="doc_subsubsection">
<a name="recordlet">'let' expressions</tt></a> <a name="recordlet">'let' expressions</a>
</div> </div>
<div class="doc_text"> <div class="doc_text">
<p> <p>A record-level let expression is used to change the value of a value
A record-level let expression is used to change the value of a value definition definition in a record. This is primarily useful when a superclass defines a
in a record. This is primarily useful when a superclass defines a value that a value that a derived class or definition wants to override. Let expressions
derived class or definition wants to override. Let expressions consist of the consist of the '<tt>let</tt>' keyword followed by a value name, an equal sign
'<tt>let</tt>' keyword followed by a value name, an equal sign ("="), and a new ("="), and a new value. For example, a new class could be added to the example
value. For example, a new class could be added to the example above, redefining above, redefining the <tt>V</tt> field for all of its subclasses:</p>
the <tt>V</tt> field for all of its subclasses:</p>
<p><pre> <pre>
<b>class</b> D : C { let V = 0; } <b>class</b> D : C { let V = 0; }
<b>def</b> Z : D; <b>def</b> Z : D;
</pre></p> </pre>
<p> <p>In this case, the <tt>Z</tt> definition will have a zero value for its "V"
In this case, the <tt>Z</tt> definition will have a zero value for its "V"
value, despite the fact that it derives (indirectly) from the <tt>C</tt> class, value, despite the fact that it derives (indirectly) from the <tt>C</tt> class,
because the <tt>D</tt> class overrode its value. because the <tt>D</tt> class overrode its value.</p>
</p>
</div> </div>
<!-----------------------------------------------------------------------------> <!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection"> <div class="doc_subsubsection">
<a name="templateargs">Class template arguments</tt></a> <a name="templateargs">Class template arguments</a>
</div> </div>
<div class="doc_text"> <div class="doc_text">
<p> <p>TableGen permits the definition of parameterized classes as well as normal
TableGen permits the definition of parameterized classes as well as normal
concrete classes. Parameterized TableGen classes specify a list of variable concrete classes. Parameterized TableGen classes specify a list of variable
bindings (which may optionally have defaults) that are bound when used. Here is bindings (which may optionally have defaults) that are bound when used. Here is
a simple example:</p> a simple example:</p>
<p><pre> <pre>
<b>class</b> FPFormat&lt;<b>bits</b>&lt;3&gt; val&gt; { <b>class</b> FPFormat&lt;<b>bits</b>&lt;3&gt; val&gt; {
<b>bits</b>&lt;3&gt; Value = val; <b>bits</b>&lt;3&gt; Value = val;
} }
@ -479,17 +415,16 @@ a simple example:</p>
<b>def</b> OneArgFPRW : FPFormat&lt;3&gt;; <b>def</b> OneArgFPRW : FPFormat&lt;3&gt;;
<b>def</b> TwoArgFP : FPFormat&lt;4&gt;; <b>def</b> TwoArgFP : FPFormat&lt;4&gt;;
<b>def</b> SpecialFP : FPFormat&lt;5&gt;; <b>def</b> SpecialFP : FPFormat&lt;5&gt;;
</pre></p> </pre>
<p> <p>In this case, template arguments are used as a space efficient way to specify
In this case, template arguments are used as a space efficient way to specify a a list of "enumeration values", each with a "Value" field set to the specified
list of "enumeration values", each with a "Value" field set to the specified
integer.</p> integer.</p>
<p>The more esoteric forms of <a href="#values">TableGen expressions</a> are <p>The more esoteric forms of <a href="#values">TableGen expressions</a> are
useful in conjunction with template arguments. As an example:</p> useful in conjunction with template arguments. As an example:</p>
<p><pre> <pre>
<b>class</b> ModRefVal&lt;<b>bits</b>&lt;2&gt; val&gt; { <b>class</b> ModRefVal&lt;<b>bits</b>&lt;2&gt; val&gt; {
<b>bits</b>&lt;2&gt; Value = val; <b>bits</b>&lt;2&gt; Value = val;
} }
@ -512,15 +447,14 @@ useful in conjunction with template arguments. As an example:</p>
<b>def</b> bork : Value&lt;Mod&gt;; <b>def</b> bork : Value&lt;Mod&gt;;
<b>def</b> zork : Value&lt;Ref&gt;; <b>def</b> zork : Value&lt;Ref&gt;;
<b>def</b> hork : Value&lt;ModRef&gt;; <b>def</b> hork : Value&lt;ModRef&gt;;
</pre></p> </pre>
<p> <p>This is obviously a contrived example, but it shows how template arguments
This is obviously a contrived example, but it shows how template arguments can can be used to decouple the interface provided to the user of the class from the
be used to decouple the interface provided to the user of the class from the
actual internal data representation expected by the class. In this case, actual internal data representation expected by the class. In this case,
running <tt>tblgen</tt> on the example prints the following definitions:</p> running <tt>tblgen</tt> on the example prints the following definitions:</p>
<p><pre> <pre>
<b>def</b> bork { <i>// Value</i> <b>def</b> bork { <i>// Value</i>
bit isMod = 1; bit isMod = 1;
bit isRef = 0; bit isRef = 0;
@ -533,61 +467,54 @@ running <tt>tblgen</tt> on the example prints the following definitions:</p>
bit isMod = 0; bit isMod = 0;
bit isRef = 1; bit isRef = 1;
} }
</pre></p> </pre>
<p> <p> This shows that TableGen was able to dig into the argument and extract a
This shows that TableGen was able to dig into the argument and extract a piece piece of information that was requested by the designer of the "Value" class.
of information that was requested by the designer of the "Value" class. For For more realistic examples, please see existing users of TableGen, such as the
more realistic examples, please see existing users of TableGen, such as the X86 X86 backend.</p>
backend.</p>
</div> </div>
<!-- ======================================================================= --> <!-- ======================================================================= -->
<div class="doc_subsection"> <div class="doc_subsection">
<a name="filescope">File scope entities</tt></a> <a name="filescope">File scope entities</a>
</div> </div>
<!-----------------------------------------------------------------------------> <!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection"> <div class="doc_subsubsection">
<a name="include">File inclusion</tt></a> <a name="include">File inclusion</a>
</div> </div>
<div class="doc_text"> <div class="doc_text">
<p> <p>TableGen supports the '<tt>include</tt>' token, which textually substitutes
TableGen supports the '<tt>include</tt>' token, which textually substitutes the the specified file in place of the include directive. The filename should be
specified file in place of the include directive. The filename should be
specified as a double quoted string immediately after the '<tt>include</tt>' specified as a double quoted string immediately after the '<tt>include</tt>'
keyword. Example: keyword. Example:</p>
<p><pre> <pre>
<b>include</b> "foo.td" <b>include</b> "foo.td"
</pre></p> </pre>
</div> </div>
<!-----------------------------------------------------------------------------> <!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection"> <div class="doc_subsubsection">
<a name="globallet">'let' expressions</tt></a> <a name="globallet">'let' expressions</a>
</div> </div>
<div class="doc_text"> <div class="doc_text">
<p> <p> "let" expressions at file scope are similar to <a href="#recordlet">"let"
"let" expressions at file scope are similar to <a href="#recordlet">"let"
expressions within a record</a>, except they can specify a value binding for expressions within a record</a>, except they can specify a value binding for
multiple records at a time, and may be useful in certain other cases. multiple records at a time, and may be useful in certain other cases.
File-scope let expressions are really just another way that TableGen allows the File-scope let expressions are really just another way that TableGen allows the
end-user to factor out commonality from the records. end-user to factor out commonality from the records.</p>
</p>
<p> <p>File-scope "let" expressions take a comma-seperated list of bindings to
File-scope "let" expressions take a comma-seperated list of bindings to apply, apply, and one of more records to bind the values in. Here are some
and one of more records to bind the values in. Here are some examples: examples:</p>
</p>
<p><pre> <pre>
<b>let</b> isTerminator = 1, isReturn = 1 <b>in</b> <b>let</b> isTerminator = 1, isReturn = 1 <b>in</b>
<b>def</b> RET : X86Inst&lt;"ret", 0xC3, RawFrm, NoArg&gt;; <b>def</b> RET : X86Inst&lt;"ret", 0xC3, RawFrm, NoArg&gt;;
@ -598,56 +525,48 @@ and one of more records to bind the values in. Here are some examples:
<b>def</b> CALLr32 : X86Inst&lt;"call", 0xFF, MRMS2r, Arg32&gt;; <b>def</b> CALLr32 : X86Inst&lt;"call", 0xFF, MRMS2r, Arg32&gt;;
<b>def</b> CALLm32 : X86Inst&lt;"call", 0xFF, MRMS2m, Arg32&gt;; <b>def</b> CALLm32 : X86Inst&lt;"call", 0xFF, MRMS2m, Arg32&gt;;
} }
</pre></p> </pre>
<p> <p>File-scope "let" expressions are often useful when a couple of definitions
File-scope "let" expressions are often useful when a couple of definitions need need to be added to several records, and the records do not otherwise need to be
to be added to several records, and the records do not otherwise need to be opened, as in the case with the CALL* instructions above.</p>
opened, as in the case with the CALL* instructions above.
</p>
</div> </div>
<!-- *********************************************************************** --> <!-- *********************************************************************** -->
<div class="doc_section"><a name="backends">TableGen backends</a></div> <div class="doc_section"><a name="backends">TableGen backends</a></div>
<!-- *********************************************************************** --> <!-- *********************************************************************** -->
<div class="doc_text"> <div class="doc_text">
<p>How they work, how to write one. This section should not contain details
<p> about any particular backend, except maybe -print-enums as an example. This
How they work, how to write one. This section should not contain details about should highlight the APIs in <tt>TableGen/Record.h</tt>.</p>
any particular backend, except maybe -print-enums as an example. This should
highlight the APIs in TableGen/Record.h.
</p>
</div> </div>
<!-- *********************************************************************** --> <!-- *********************************************************************** -->
<div class="doc_section"><a name="codegenerator">The LLVM code generator</a></div> <div class="doc_section"><a name="codegenerator">The LLVM code generator</a>
</div>
<!-- *********************************************************************** --> <!-- *********************************************************************** -->
<div class="doc_text"> <div class="doc_text">
<p>This is just a temporary, convenient, place to put stuff about the code
<p>
This is just a temporary, convenient, place to put stuff about the code
generator before it gets its own document. This should describe all of the generator before it gets its own document. This should describe all of the
tablegen backends used by the code generator and the classes/definitions they tablegen backends used by the code generator and the classes/definitions they
expect. expect.</p>
</p>
</div> </div>
<!-- *********************************************************************** --> <!-- *********************************************************************** -->
<hr> <hr>
<div class="doc_footer"> <address>
<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address> <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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