"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
+ <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>TableGen Fundamentals</title>
- <link rel="stylesheet" href="llvm.css" type="text/css">
+ <link rel="stylesheet" href="_static/llvm.css" type="text/css">
</head>
<body>
-<div class="doc_title">TableGen Fundamentals</div>
+<h1>TableGen Fundamentals</h1>
-<div class="doc_text">
+<div>
<ul>
<li><a href="#introduction">Introduction</a>
<ol>
<ol>
<li><a href="#include">File inclusion</a></li>
<li><a href="#globallet">'let' expressions</a></li>
+ <li><a href="#foreach">'foreach' blocks</a></li>
</ol></li>
</ol></li>
<li><a href="#backends">TableGen backends</a>
</div>
<!-- *********************************************************************** -->
-<div class="doc_section"><a name="introduction">Introduction</a></div>
+<h2><a name="introduction">Introduction</a></h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>TableGen's purpose is to help a human develop and maintain records of
domain-specific information. Because there may be a large number of these
<tt>llvm/utils/emacs</tt> and <tt>llvm/utils/vim</tt> directories of your LLVM
distribution, respectively.</p>
-</div>
-
<!-- ======================================================================= -->
-<div class="doc_subsection"><a name="concepts">Basic concepts</a></div>
+<h3><a name="concepts">Basic concepts</a></h3>
-<div class="doc_text">
+<div>
<p>TableGen files consist of two key parts: 'classes' and 'definitions', both
of which are considered 'records'.</p>
as "Instruction".</p>
<p><b>TableGen multiclasses</b> are groups of abstract records that are
-instantiated all at once. Each instantiation can result in multiple TableGen
-definitions.</p>
+instantiated all at once. Each instantiation can result in multiple
+TableGen definitions. If a multiclass inherits from another multiclass,
+the definitions in the sub-multiclass become part of the current
+multiclass, as if they were declared in the current multiclass.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection"><a name="example">An example record</a></div>
+<h3><a name="example">An example record</a></h3>
-<div class="doc_text">
+<div>
<p>With no other arguments, TableGen parses the specified file and prints out
all of the classes, then all of the definitions. This is a good way to see what
<b>bit</b> mayLoad = 0;
<b>bit</b> mayStore = 0;
<b>bit</b> isImplicitDef = 0;
- <b>bit</b> isTwoAddress = 1;
<b>bit</b> isConvertibleToThreeAddress = 1;
<b>bit</b> isCommutable = 1;
<b>bit</b> isTerminator = 0;
<b>bit</b> isReMaterializable = 0;
<b>bit</b> isPredicable = 0;
<b>bit</b> hasDelaySlot = 0;
- <b>bit</b> usesCustomDAGSchedInserter = 0;
+ <b>bit</b> usesCustomInserter = 0;
<b>bit</b> hasCtrlDep = 0;
<b>bit</b> isNotDuplicable = 0;
<b>bit</b> hasSideEffects = 0;
- <b>bit</b> mayHaveSideEffects = 0;
<b>bit</b> neverHasSideEffects = 0;
InstrItinClass Itinerary = NoItinerary;
<b>string</b> Constraints = "";
<p>As you can see, a lot of information is needed for every instruction
supported by the code generator, and specifying it all manually would be
-unmaintainble, prone to bugs, and tiring to do in the first place. Because we
+unmaintainable, prone to bugs, and tiring to do in the first place. Because we
are using TableGen, all of the information was derived from the following
definition:</p>
key feature of TableGen is that it allows the end-user to define the
abstractions they prefer to use when describing their information.</p>
+<p>Each def record has a special entry called "NAME." This is the
+name of the def ("ADD32rr" above). In the general case def names can
+be formed from various kinds of string processing expressions and NAME
+resolves to the final value obtained after resolving all of those
+expressions. The user may refer to NAME anywhere she desires to use
+the ultimate name of the def. NAME should not be defined anywhere
+else in user code to avoid conflict problems.</p>
+
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection"><a name="running">Running TableGen</a></div>
+<h3><a name="running">Running TableGen</a></h3>
-<div class="doc_text">
+<div>
<p>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>
-reads from standard input.</p>
+specifies the file to read. If a filename is not specified,
+<tt>llvm-tblgen</tt> reads from standard input.</p>
<p>To be useful, one of the <a href="#backends">TableGen backends</a> must be
-used. These backends are selectable on the command line (type '<tt>tblgen
+used. These backends are selectable on the command line (type '<tt>llvm-tblgen
-help</tt>' for a list). For example, to get a list of all of the definitions
that subclass a particular type (which can be useful for building up an enum
list of these records), use the <tt>-print-enums</tt> option:</p>
<div class="doc_code">
<pre>
-$ tblgen X86.td -print-enums -class=Register
+$ llvm-tblgen X86.td -print-enums -class=Register
AH, AL, AX, BH, BL, BP, BPL, BX, CH, CL, CX, DH, DI, DIL, DL, DX, EAX, EBP, EBX,
ECX, EDI, EDX, EFLAGS, EIP, ESI, ESP, FP0, FP1, FP2, FP3, FP4, FP5, FP6, IP,
MM0, MM1, MM2, MM3, MM4, MM5, MM6, MM7, R10, R10B, R10D, R10W, R11, R11B, R11D,
XMM0, XMM1, XMM10, XMM11, XMM12, XMM13, XMM14, XMM15, XMM2, XMM3, XMM4, XMM5,
XMM6, XMM7, XMM8, XMM9,
-$ tblgen X86.td -print-enums -class=Instruction
+$ llvm-tblgen X86.td -print-enums -class=Instruction
ABS_F, ABS_Fp32, ABS_Fp64, ABS_Fp80, ADC32mi, ADC32mi8, ADC32mr, ADC32ri,
ADC32ri8, ADC32rm, ADC32rr, ADC64mi32, ADC64mi8, ADC64mr, ADC64ri32, ADC64ri8,
ADC64rm, ADC64rr, ADD16mi, ADD16mi8, ADD16mr, ADD16ri, ADD16ri8, ADD16rm,
</div>
+</div>
<!-- *********************************************************************** -->
-<div class="doc_section"><a name="syntax">TableGen syntax</a></div>
+<h2><a name="syntax">TableGen syntax</a></h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>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.
</p>
-</div>
-
<!-- ======================================================================= -->
-<div class="doc_subsection"><a name="primitives">TableGen primitives</a></div>
+<h3><a name="primitives">TableGen primitives</a></h3>
+
+<div>
<!-- -------------------------------------------------------------------------->
-<div class="doc_subsubsection"><a name="comments">TableGen comments</a></div>
+<h4><a name="comments">TableGen comments</a></h4>
-<div class="doc_text">
+<div>
<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>
</div>
<!-- -------------------------------------------------------------------------->
-<div class="doc_subsubsection">
+<h4>
<a name="types">The TableGen type system</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>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
<dd>This type represents a nestable directed graph of elements.</dd>
<dt><tt><b>code</b></tt></dt>
- <dd>This represents a big hunk of text. NOTE: I don't remember why this is
- distinct from string!</dd>
+ <dd>This represents a big hunk of text. This is lexically distinct from
+ string values because it doesn't require escapeing double quotes and other
+ common characters that occur in code.</dd>
</dl>
<p>To date, these types have been sufficient for describing things that
</div>
<!-- -------------------------------------------------------------------------->
-<div class="doc_subsubsection">
+<h4>
<a name="values">TableGen values and expressions</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>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
<dd>string value</dd>
<dt><tt>[{ ... }]</tt></dt>
<dd>code fragment</dd>
-<dt><tt>[ X, Y, Z ]</tt></dt>
- <dd>list value.</dd>
+<dt><tt>[ X, Y, Z ]<type></tt></dt>
+ <dd>list value. <type> is the type of the list
+element and is usually optional. In rare cases,
+TableGen is unable to deduce the element type in
+which case the user must specify it explicitly.</dd>
<dt><tt>{ a, b, c }</tt></dt>
<dd>initializer for a "bits<3>" value</dd>
<dt><tt>value</tt></dt>
<dt><tt>list[4-7,17,2-3]</tt></dt>
<dd>A slice of the 'list' list, including elements 4,5,6,7,17,2, and 3 from
it. Elements may be included multiple times.</dd>
+<dt><tt>foreach <var> = [ <list> ] in { <body> }</tt></dt>
+<dt><tt>foreach <var> = [ <list> ] in <def></tt></dt>
+ <dd> Replicate <body> or <def>, replacing instances of
+ <var> with each value in <list>. <var> is scoped at the
+ level of the <tt>foreach</tt> loop and must not conflict with any other object
+ introduced in <body> or <def>. Currently only <tt>def</tt>s are
+ expanded within <body>.
+ </dd>
+<dt><tt>foreach <var> = 0-15 in ...</tt></dt>
+<dt><tt>foreach <var> = {0-15,32-47} in ...</tt></dt>
+ <dd>Loop over ranges of integers. The braces are required for multiple
+ ranges.</dd>
<dt><tt>(DEF a, b)</tt></dt>
<dd>a dag value. The first element is required to be a record definition, the
remaining elements in the list may be arbitrary other values, including nested
<dt><tt>!strconcat(a, b)</tt></dt>
<dd>A string value that is the result of concatenating the 'a' and 'b'
strings.</dd>
+<dt><tt>str1#str2</tt></dt>
+ <dd>"#" (paste) is a shorthand for !strconcat. It may concatenate
+ things that are not quoted strings, in which case an implicit
+ !cast<string> is done on the operand of the paste.</dd>
+<dt><tt>!cast<type>(a)</tt></dt>
+ <dd>A symbol of type <em>type</em> obtained by looking up the string 'a' in
+the symbol table. If the type of 'a' does not match <em>type</em>, TableGen
+aborts with an error. !cast<string> is a special case in that the argument must
+be an object defined by a 'def' construct.</dd>
+<dt><tt>!subst(a, b, c)</tt></dt>
+ <dd>If 'a' and 'b' are of string type or are symbol references, substitute
+'b' for 'a' in 'c.' This operation is analogous to $(subst) in GNU make.</dd>
+<dt><tt>!foreach(a, b, c)</tt></dt>
+ <dd>For each member 'b' of dag or list 'a' apply operator 'c.' 'b' is a
+dummy variable that should be declared as a member variable of an instantiated
+class. This operation is analogous to $(foreach) in GNU make.</dd>
+<dt><tt>!head(a)</tt></dt>
+ <dd>The first element of list 'a.'</dd>
+<dt><tt>!tail(a)</tt></dt>
+ <dd>The 2nd-N elements of list 'a.'</dd>
+<dt><tt>!empty(a)</tt></dt>
+ <dd>An integer {0,1} indicating whether list 'a' is empty.</dd>
+<dt><tt>!if(a,b,c)</tt></dt>
+ <dd>'b' if the result of 'int' or 'bit' operator 'a' is nonzero,
+ 'c' otherwise.</dd>
+<dt><tt>!eq(a,b)</tt></dt>
+ <dd>'bit 1' if string a is equal to string b, 0 otherwise. This
+ only operates on string, int and bit objects. Use !cast<string> to
+ compare other types of objects.</dd>
</dl>
<p>Note that all of the values have rules specifying how they convert to values
</div>
+</div>
+
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="classesdefs">Classes and definitions</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p>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
permit the specification of default values for their subclasses, allowing the
subclasses to override them as they wish.</p>
-</div>
-
<!---------------------------------------------------------------------------->
-<div class="doc_subsubsection">
+<h4>
<a name="valuedef">Value definitions</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>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
</div>
<!-- -------------------------------------------------------------------------->
-<div class="doc_subsubsection">
+<h4>
<a name="recordlet">'let' expressions</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>A record-level let expression is used to change the value of a value
definition in a record. This is primarily useful when a superclass defines a
</div>
<!-- -------------------------------------------------------------------------->
-<div class="doc_subsubsection">
+<h4>
<a name="templateargs">Class template arguments</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>TableGen permits the definition of parameterized classes as well as normal
concrete classes. Parameterized TableGen classes specify a list of variable
<p>This is obviously a contrived example, but it shows how template arguments
can 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,
-running <tt>tblgen</tt> on the example prints the following definitions:</p>
+running <tt>llvm-tblgen</tt> on the example prints the following
+definitions:</p>
<div class="doc_code">
<pre>
</div>
<!-- -------------------------------------------------------------------------->
-<div class="doc_subsubsection">
+<h4>
<a name="multiclass">Multiclass definitions and instances</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>
While classes with template arguments are a good way to factor commonality
<p>The name of the resultant definitions has the multidef fragment names
appended to them, so this defines <tt>ADD_rr</tt>, <tt>ADD_ri</tt>,
- <tt>SUB_rr</tt>, etc. Using a multiclass this way is exactly equivalent to
- instantiating the classes multiple times yourself, e.g. by writing:</p>
+ <tt>SUB_rr</tt>, etc. A defm may inherit from multiple multiclasses,
+ instantiating definitions from each multiclass. Using a multiclass
+ this way is exactly equivalent to instantiating the classes multiple
+ times yourself, e.g. by writing:</p>
<div class="doc_code">
<pre>
</pre>
</div>
+<p>
+A defm can also be used inside a multiclass providing several levels of
+multiclass instanciations.
+</p>
+
+<div class="doc_code">
+<pre>
+<b>class</b> Instruction<bits<4> opc, string Name> {
+ bits<4> opcode = opc;
+ string name = Name;
+}
+
+<b>multiclass</b> basic_r<bits<4> opc> {
+ <b>def</b> rr : Instruction<opc, "rr">;
+ <b>def</b> rm : Instruction<opc, "rm">;
+}
+
+<b>multiclass</b> basic_s<bits<4> opc> {
+ <b>defm</b> SS : basic_r<opc>;
+ <b>defm</b> SD : basic_r<opc>;
+ <b>def</b> X : Instruction<opc, "x">;
+}
+
+<b>multiclass</b> basic_p<bits<4> opc> {
+ <b>defm</b> PS : basic_r<opc>;
+ <b>defm</b> PD : basic_r<opc>;
+ <b>def</b> Y : Instruction<opc, "y">;
+}
+
+<b>defm</b> ADD : basic_s<0xf>, basic_p<0xf>;
+...
+
+<i>// Results</i>
+<b>def</b> ADDPDrm { ...
+<b>def</b> ADDPDrr { ...
+<b>def</b> ADDPSrm { ...
+<b>def</b> ADDPSrr { ...
+<b>def</b> ADDSDrm { ...
+<b>def</b> ADDSDrr { ...
+<b>def</b> ADDY { ...
+<b>def</b> ADDX { ...
+</pre>
+</div>
+
+<p>
+defm declarations can inherit from classes too, the
+rule to follow is that the class list must start after the
+last multiclass, and there must be at least one multiclass
+before them.
+</p>
+
+<div class="doc_code">
+<pre>
+<b>class</b> XD { bits<4> Prefix = 11; }
+<b>class</b> XS { bits<4> Prefix = 12; }
+
+<b>class</b> I<bits<4> op> {
+ bits<4> opcode = op;
+}
+
+<b>multiclass</b> R {
+ <b>def</b> rr : I<4>;
+ <b>def</b> rm : I<2>;
+}
+
+<b>multiclass</b> Y {
+ <b>defm</b> SS : R, XD;
+ <b>defm</b> SD : R, XS;
+}
+
+<b>defm</b> Instr : Y;
+
+<i>// Results</i>
+<b>def</b> InstrSDrm {
+ bits<4> opcode = { 0, 0, 1, 0 };
+ bits<4> Prefix = { 1, 1, 0, 0 };
+}
+...
+<b>def</b> InstrSSrr {
+ bits<4> opcode = { 0, 1, 0, 0 };
+ bits<4> Prefix = { 1, 0, 1, 1 };
+}
+</pre>
+</div>
+
+</div>
+
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="filescope">File scope entities</a>
-</div>
+</h3>
+
+<div>
<!-- -------------------------------------------------------------------------->
-<div class="doc_subsubsection">
+<h4>
<a name="include">File inclusion</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>TableGen supports the '<tt>include</tt>' token, which textually substitutes
the specified file in place of the include directive. The filename should be
specified as a double quoted string immediately after the '<tt>include</tt>'
</div>
<!-- -------------------------------------------------------------------------->
-<div class="doc_subsubsection">
+<h4>
<a name="globallet">'let' expressions</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>"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
need to be added to several records, and the records do not otherwise need to be
opened, as in the case with the <tt>CALL*</tt> instructions above.</p>
+<p>It's also possible to use "let" expressions inside multiclasses, providing
+more ways to factor out commonality from the records, specially if using
+several levels of multiclass instanciations. This also avoids the need of using
+"let" expressions within subsequent records inside a multiclass.</p>
+
+<pre class="doc_code">
+<b>multiclass </b>basic_r<bits<4> opc> {
+ <b>let </b>Predicates = [HasSSE2] in {
+ <b>def </b>rr : Instruction<opc, "rr">;
+ <b>def </b>rm : Instruction<opc, "rm">;
+ }
+ <b>let </b>Predicates = [HasSSE3] in
+ <b>def </b>rx : Instruction<opc, "rx">;
+}
+
+<b>multiclass </b>basic_ss<bits<4> opc> {
+ <b>let </b>IsDouble = 0 in
+ <b>defm </b>SS : basic_r<opc>;
+
+ <b>let </b>IsDouble = 1 in
+ <b>defm </b>SD : basic_r<opc>;
+}
+
+<b>defm </b>ADD : basic_ss<0xf>;
+</pre>
+</div>
+
+<!-- -------------------------------------------------------------------------->
+<h4>
+ <a name="foreach">Looping</a>
+</h4>
+
+<div>
+<p>TableGen supports the '<tt>foreach</tt>' block, which textually replicates
+the loop body, substituting iterator values for iterator references in the
+body. Example:</p>
+
+<div class="doc_code">
+<pre>
+<b>foreach</b> i = [0, 1, 2, 3] in {
+ <b>def</b> R#i : Register<...>;
+ <b>def</b> F#i : Register<...>;
+}
+</pre>
+</div>
+
+<p>This will create objects <tt>R0</tt>, <tt>R1</tt>, <tt>R2</tt> and
+<tt>R3</tt>. <tt>foreach</tt> blocks may be nested. If there is only
+one item in the body the braces may be elided:</p>
+
+<div class="doc_code">
+<pre>
+<b>foreach</b> i = [0, 1, 2, 3] in
+ <b>def</b> R#i : Register<...>;
+
+</pre>
+</div>
+
+</div>
+
+</div>
+
+</div>
+
+<!-- *********************************************************************** -->
+<h2><a name="codegen">Code Generator backend info</a></h2>
+<!-- *********************************************************************** -->
+
+<div>
+
+<p>Expressions used by code generator to describe instructions and isel
+patterns:</p>
+
+<dl>
+<dt><tt>(implicit a)</tt></dt>
+ <dd>an implicitly defined physical register. This tells the dag instruction
+ selection emitter the input pattern's extra definitions matches implicit
+ physical register definitions.</dd>
+</dl>
</div>
<!-- *********************************************************************** -->
-<div class="doc_section"><a name="backends">TableGen backends</a></div>
+<h2><a name="backends">TableGen backends</a></h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>TODO: How they work, how to write one. This section should not contain
details about any particular backend, except maybe -print-enums as an example.
<hr>
<address>
<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
- src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
+ src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
<a href="http://validator.w3.org/check/referer"><img
- src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
+ src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
- <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
+ <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Last modified: $Date$
</address>
projects / oota-llvm.git / blobdiff