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10<div class="doc_title">TableGen Fundamentals</div>
11
Misha Brukman85234ac2004-05-12 18:31:21 +000012<div class="doc_text">
Chris Lattnerb54c99c2004-02-06 05:42:53 +000013<ul>
Misha Brukman85234ac2004-05-12 18:31:21 +000014 <li><a href="#introduction">Introduction</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000015 <ol>
16 <li><a href="#concepts">Basic concepts</a></li>
17 <li><a href="#example">An example record</a></li>
18 <li><a href="#running">Running TableGen</a></li>
Misha Brukman85234ac2004-05-12 18:31:21 +000019 </ol></li>
20 <li><a href="#syntax">TableGen syntax</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000021 <ol>
Misha Brukman85234ac2004-05-12 18:31:21 +000022 <li><a href="#primitives">TableGen primitives</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000023 <ol>
24 <li><a href="#comments">TableGen comments</a></li>
25 <li><a href="#types">The TableGen type system</a></li>
26 <li><a href="#values">TableGen values and expressions</a></li>
Misha Brukman85234ac2004-05-12 18:31:21 +000027 </ol></li>
28 <li><a href="#classesdefs">Classes and definitions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000029 <ol>
30 <li><a href="#valuedef">Value definitions</a></li>
31 <li><a href="#recordlet">'let' expressions</a></li>
32 <li><a href="#templateargs">Class template arguments</a></li>
Chris Lattner84b35982006-09-01 21:44:18 +000033 <li><a href="#multiclass">Multiclass definitions and instances</a></li>
Misha Brukman85234ac2004-05-12 18:31:21 +000034 </ol></li>
35 <li><a href="#filescope">File scope entities</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000036 <ol>
37 <li><a href="#include">File inclusion</a></li>
38 <li><a href="#globallet">'let' expressions</a></li>
Misha Brukman85234ac2004-05-12 18:31:21 +000039 </ol></li>
40 </ol></li>
41 <li><a href="#backends">TableGen backends</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000042 <ol>
Chris Lattnerfa6f3092004-02-06 06:04:25 +000043 <li><a href="#">todo</a></li>
Misha Brukman85234ac2004-05-12 18:31:21 +000044 </ol></li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000045</ul>
Misha Brukman85234ac2004-05-12 18:31:21 +000046</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000047
Chris Lattner7911ce22004-05-23 21:07:27 +000048<div class="doc_author">
49 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></p>
50</div>
51
Chris Lattnerb54c99c2004-02-06 05:42:53 +000052<!-- *********************************************************************** -->
53<div class="doc_section"><a name="introduction">Introduction</a></div>
54<!-- *********************************************************************** -->
55
56<div class="doc_text">
57
58<p>TableGen's purpose is to help a human develop and maintain records of
59domain-specific information. Because there may be a large number of these
60records, it is specifically designed to allow writing flexible descriptions and
61for common features of these records to be factored out. This reduces the
62amount of duplication in the description, reduces the chance of error, and
63makes it easier to structure domain specific information.</p>
64
65<p>The core part of TableGen <a href="#syntax">parses a file</a>, instantiates
66the declarations, and hands the result off to a domain-specific "<a
67href="#backends">TableGen backend</a>" for processing. The current major user
Chris Lattner1aab3272004-07-26 21:16:55 +000068of TableGen is the <a href="CodeGenerator.html">LLVM code generator</a>.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000069
Misha Brukman85234ac2004-05-12 18:31:21 +000070<p>Note that if you work on TableGen much, and use emacs or vim, that you can
71find an emacs "TableGen mode" and a vim language file in
72<tt>llvm/utils/emacs</tt> and <tt>llvm/utils/vim</tt> directory of your LLVM
73distribution, respectively.</p>
Chris Lattnerfa6f3092004-02-06 06:04:25 +000074
Chris Lattnerb54c99c2004-02-06 05:42:53 +000075</div>
76
77<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +000078<div class="doc_subsection"><a name="running">Basic concepts</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000079
80<div class="doc_text">
81
Misha Brukman85234ac2004-05-12 18:31:21 +000082<p>TableGen files consist of two key parts: 'classes' and 'definitions', both
83of which are considered 'records'.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000084
Misha Brukman85234ac2004-05-12 18:31:21 +000085<p><b>TableGen records</b> have a unique name, a list of values, and a list of
Chris Lattnerb54c99c2004-02-06 05:42:53 +000086superclasses. The list of values is main data that TableGen builds for each
87record, it is this that holds the domain specific information for the
88application. The interpretation of this data is left to a specific <a
89href="#backends">TableGen backend</a>, but the structure and format rules are
Misha Brukman85234ac2004-05-12 18:31:21 +000090taken care of and fixed by TableGen.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000091
Misha Brukman85234ac2004-05-12 18:31:21 +000092<p><b>TableGen definitions</b> are the concrete form of 'records'. These
93generally do not have any undefined values, and are marked with the
94'<tt>def</tt>' keyword.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +000095
Misha Brukman85234ac2004-05-12 18:31:21 +000096<p><b>TableGen classes</b> are abstract records that are used to build and
97describe other records. These 'classes' allow the end-user to build
98abstractions for either the domain they are targetting (such as "Register",
99"RegisterClass", and "Instruction" in the LLVM code generator) or for the
100implementor to help factor out common properties of records (such as "FPInst",
101which is used to represent floating point instructions in the X86 backend).
102TableGen keeps track of all of the classes that are used to build up a
103definition, so the backend can find all definitions of a particular class, such
104as "Instruction".</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000105
Chris Lattner84b35982006-09-01 21:44:18 +0000106<p><b>TableGen multiclasses</b> are groups of abstract records that are
107instantiated all at once. Each instantiation can result in multiple TableGen
108definitions.</p>
109
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000110</div>
111
112<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000113<div class="doc_subsection"><a name="example">An example record</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000114
115<div class="doc_text">
116
Misha Brukman85234ac2004-05-12 18:31:21 +0000117<p>With no other arguments, TableGen parses the specified file and prints out
118all of the classes, then all of the definitions. This is a good way to see what
119the various definitions expand to fully. Running this on the <tt>X86.td</tt>
120file prints this (at the time of this writing):</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000121
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000122<pre>
123...
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000124<b>def</b> ADDrr8 { <i>// Instruction X86Inst I2A8 Pattern</i>
125 <b>string</b> Name = "add";
126 <b>string</b> Namespace = "X86";
127 <b>list</b>&lt;Register&gt; Uses = [];
128 <b>list</b>&lt;Register&gt; Defs = [];
129 <b>bit</b> isReturn = 0;
130 <b>bit</b> isBranch = 0;
131 <b>bit</b> isCall = 0;
132 <b>bit</b> isTwoAddress = 1;
133 <b>bit</b> isTerminator = 0;
134 <b>dag</b> Pattern = (set R8, (plus R8, R8));
135 <b>bits</b>&lt;8&gt; Opcode = { 0, 0, 0, 0, 0, 0, 0, 0 };
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000136 Format Form = MRMDestReg;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000137 <b>bits</b>&lt;5&gt; FormBits = { 0, 0, 0, 1, 1 };
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000138 ArgType Type = Arg8;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000139 <b>bits</b>&lt;3&gt; TypeBits = { 0, 0, 1 };
140 <b>bit</b> hasOpSizePrefix = 0;
141 <b>bit</b> printImplicitUses = 0;
142 <b>bits</b>&lt;4&gt; Prefix = { 0, 0, 0, 0 };
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000143 FPFormat FPForm = ?;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000144 <b>bits</b>&lt;3&gt; FPFormBits = { 0, 0, 0 };
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000145}
146...
Misha Brukman85234ac2004-05-12 18:31:21 +0000147</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000148
Misha Brukman85234ac2004-05-12 18:31:21 +0000149<p>This definition corresponds to an 8-bit register-register add instruction in
150the X86. The string after the '<tt>def</tt>' string indicates the name of the
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000151record ("<tt>ADDrr8</tt>" in this case), and the comment at the end of the line
152indicates the superclasses of the definition. The body of the record contains
153all of the data that TableGen assembled for the record, indicating that the
154instruction is part of the "X86" namespace, should be printed as "<tt>add</tt>"
155in the assembly file, it is a two-address instruction, has a particular
156encoding, etc. The contents and semantics of the information in the record is
Misha Brukman85234ac2004-05-12 18:31:21 +0000157specific to the needs of the X86 backend, and is only shown as an example.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000158
Misha Brukman85234ac2004-05-12 18:31:21 +0000159<p>As you can see, a lot of information is needed for every instruction
160supported by the code generator, and specifying it all manually would be
161unmaintainble, prone to bugs, and tiring to do in the first place. Because we
162are using TableGen, all of the information was derived from the following
163definition:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000164
Misha Brukman85234ac2004-05-12 18:31:21 +0000165<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000166<b>def</b> ADDrr8 : I2A8&lt;"add", 0x00, MRMDestReg&gt;,
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000167 Pattern&lt;(set R8, (plus R8, R8))&gt;;
Misha Brukman85234ac2004-05-12 18:31:21 +0000168</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000169
Misha Brukman85234ac2004-05-12 18:31:21 +0000170<p>This definition makes use of the custom I2A8 (two address instruction with
1718-bit operand) class, which is defined in the X86-specific TableGen file to
172factor out the common features that instructions of its class share. A key
173feature of TableGen is that it allows the end-user to define the abstractions
174they prefer to use when describing their information.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000175
176</div>
177
178<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000179<div class="doc_subsection"><a name="running">Running TableGen</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000180
181<div class="doc_text">
182
Misha Brukman85234ac2004-05-12 18:31:21 +0000183<p>TableGen runs just like any other LLVM tool. The first (optional) argument
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000184specifies the file to read. If a filename is not specified, <tt>tblgen</tt>
Misha Brukman85234ac2004-05-12 18:31:21 +0000185reads from standard input.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000186
Misha Brukman85234ac2004-05-12 18:31:21 +0000187<p>To be useful, one of the <a href="#backends">TableGen backends</a> must be
188used. These backends are selectable on the command line (type '<tt>tblgen
189--help</tt>' for a list). For example, to get a list of all of the definitions
190that subclass a particular type (which can be useful for building up an enum
191list of these records), use the <tt>--print-enums</tt> option:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000192
Misha Brukman85234ac2004-05-12 18:31:21 +0000193<pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000194$ tblgen X86.td -print-enums -class=Register
195AH, AL, AX, BH, BL, BP, BX, CH, CL, CX, DH, DI, DL, DX,
196EAX, EBP, EBX, ECX, EDI, EDX, ESI, ESP, FP0, FP1, FP2, FP3, FP4, FP5, FP6,
197SI, SP, ST0, ST1, ST2, ST3, ST4, ST5, ST6, ST7,
198
199$ tblgen X86.td -print-enums -class=Instruction
200ADCrr32, ADDri16, ADDri16b, ADDri32, ADDri32b, ADDri8, ADDrr16, ADDrr32,
201ADDrr8, ADJCALLSTACKDOWN, ADJCALLSTACKUP, ANDri16, ANDri16b, ANDri32, ANDri32b,
202ANDri8, ANDrr16, ANDrr32, ANDrr8, BSWAPr32, CALLm32, CALLpcrel32, ...
Misha Brukman85234ac2004-05-12 18:31:21 +0000203</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000204
Misha Brukman85234ac2004-05-12 18:31:21 +0000205<p>The default backend prints out all of the records, as described <a
206href="#example">above</a>.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000207
Misha Brukman85234ac2004-05-12 18:31:21 +0000208<p>If you plan to use TableGen for some purpose, you will most likely have to
209<a href="#backends">write a backend</a> that extracts the information specific
210to what you need and formats it in the appropriate way.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000211
212</div>
213
214
215<!-- *********************************************************************** -->
216<div class="doc_section"><a name="syntax">TableGen syntax</a></div>
217<!-- *********************************************************************** -->
218
219<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000220<p>TableGen doesn't care about the meaning of data (that is up to the backend
221to define), but it does care about syntax, and it enforces a simple type system.
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000222This section describes the syntax and the constructs allowed in a TableGen file.
223</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000224</div>
225
226<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000227<div class="doc_subsection"><a name="primitives">TableGen primitives</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000228
Misha Brukman85234ac2004-05-12 18:31:21 +0000229<!-- -------------------------------------------------------------------------->
230<div class="doc_subsubsection"><a name="comments">TableGen comments</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000231
232<div class="doc_text">
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000233<p>TableGen supports BCPL style "<tt>//</tt>" comments, which run to the end of
234the line, and it also supports <b>nestable</b> "<tt>/* */</tt>" comments.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000235</div>
236
Misha Brukman85234ac2004-05-12 18:31:21 +0000237<!-- -------------------------------------------------------------------------->
Misha Brukman78b648c2004-06-03 16:59:59 +0000238<div class="doc_subsubsection">
239 <a name="types">The TableGen type system</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000240</div>
241
242<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000243<p>TableGen files are strongly typed, in a simple (but complete) type-system.
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000244These types are used to perform automatic conversions, check for errors, and to
245help interface designers constrain the input that they allow. Every <a
246href="#valuedef">value definition</a> is required to have an associated type.
247</p>
248
Misha Brukman85234ac2004-05-12 18:31:21 +0000249<p>TableGen supports a mixture of very low-level types (such as <tt>bit</tt>)
250and very high-level types (such as <tt>dag</tt>). This flexibility is what
251allows it to describe a wide range of information conveniently and compactly.
252The TableGen types are:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000253
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000254<ul>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000255<li>"<tt><b>bit</b></tt>" - A 'bit' is a boolean value that can hold either 0 or
Chris Lattnerb54c99c2004-02-06 05:42:53 +00002561.</li>
257
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000258<li>"<tt><b>int</b></tt>" - The 'int' type represents a simple 32-bit integer
259value, such as 5.</li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000260
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000261<li>"<tt><b>string</b></tt>" - The 'string' type represents an ordered sequence
262of characters of arbitrary length.</li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000263
John Criswellaa55c8c2004-02-12 18:11:53 +0000264<li>"<tt><b>bits</b>&lt;n&gt;</tt>" - A 'bits' type is an arbitrary, but fixed,
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000265size integer that is broken up into individual bits. This type is useful
266because it can handle some bits being defined while others are undefined.</li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000267
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000268<li>"<tt><b>list</b>&lt;ty&gt;</tt>" - This type represents a list whose
269elements are some other type. The contained type is arbitrary: it can even be
270another list type.</li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000271
272<li>Class type - Specifying a class name in a type context means that the
273defined value must be a subclass of the specified class. This is useful in
274conjunction with the "list" type, for example, to constrain the elements of the
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000275list to a common base class (e.g., a <tt><b>list</b>&lt;Register&gt;</tt> can
276only contain definitions derived from the "<tt>Register</tt>" class).</li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000277
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000278<li>"<tt><b>code</b></tt>" - This represents a big hunk of text. NOTE: I don't
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000279remember why this is distinct from string!</li>
280
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000281<li>"<tt><b>dag</b></tt>" - This type represents a nestable directed graph of
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000282elements.</li>
283</ul>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000284
Misha Brukman85234ac2004-05-12 18:31:21 +0000285<p>To date, these types have been sufficient for describing things that
286TableGen has been used for, but it is straight-forward to extend this list if
287needed.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000288
289</div>
290
Misha Brukman85234ac2004-05-12 18:31:21 +0000291<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000292<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000293 <a name="values">TableGen values and expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000294</div>
295
Misha Brukman78b648c2004-06-03 16:59:59 +0000296<div class="doc_text">
297
Misha Brukman85234ac2004-05-12 18:31:21 +0000298<p>TableGen allows for a pretty reasonable number of different expression forms
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000299when building up values. These forms allow the TableGen file to be written in a
300natural syntax and flavor for the application. The current expression forms
Misha Brukman85234ac2004-05-12 18:31:21 +0000301supported include:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000302
Misha Brukman85234ac2004-05-12 18:31:21 +0000303<ul>
Misha Brukman08772da2004-07-28 22:09:29 +0000304<li><tt>?</tt> - uninitialized field</li>
305<li><tt>0b1001011</tt> - binary integer value</li>
306<li><tt>07654321</tt> - octal integer value (indicated by a leading 0)</li>
307<li><tt>7</tt> - decimal integer value</li>
308<li><tt>0x7F</tt> - hexadecimal integer value</li>
309<li><tt>"foo"</tt> - string value</li>
310<li><tt>[{ ... }]</tt> - code fragment</li>
311<li><tt>[ X, Y, Z ]</tt> - list value.</li>
312<li><tt>{ a, b, c }</tt> - initializer for a "bits&lt;3&gt;" value</li>
313<li><tt>value</tt> - value reference</li>
314<li><tt>value{17}</tt> - access to one bit of a value</li>
315<li><tt>value{15-17}</tt> - access to multiple bits of a value</li>
316<li><tt>DEF</tt> - reference to a record definition</li>
Chris Lattner33694cf2005-09-08 18:47:21 +0000317<li><tt>CLASS&lt;val list&gt;</tt> - reference to a new anonymous definition of
318 CLASS with the specified template arguments.</li>
Misha Brukman08772da2004-07-28 22:09:29 +0000319<li><tt>X.Y</tt> - reference to the subfield of a value</li>
Misha Brukman33066e92004-08-04 22:00:05 +0000320<li><tt>list[4-7,17,2-3]</tt> - A slice of the 'list' list, including elements
3214,5,6,7,17,2, and 3 from it. Elements may be included multiple times.</li>
Misha Brukman08772da2004-07-28 22:09:29 +0000322<li><tt>(DEF a, b)</tt> - a dag value. The first element is required to be a
323record definition, the remaining elements in the list may be arbitrary other
324values, including nested `<tt>dag</tt>' values.</li>
Misha Brukman85234ac2004-05-12 18:31:21 +0000325</ul>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000326
Misha Brukman85234ac2004-05-12 18:31:21 +0000327<p>Note that all of the values have rules specifying how they convert to values
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000328for different types. These rules allow you to assign a value like "7" to a
Misha Brukman85234ac2004-05-12 18:31:21 +0000329"bits&lt;4&gt;" value, for example.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000330
331</div>
332
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000333<!-- ======================================================================= -->
Misha Brukman78b648c2004-06-03 16:59:59 +0000334<div class="doc_subsection">
335 <a name="classesdefs">Classes and definitions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000336</div>
337
Misha Brukman78b648c2004-06-03 16:59:59 +0000338<div class="doc_text">
339
Misha Brukman85234ac2004-05-12 18:31:21 +0000340<p>As mentioned in the <a href="#concepts">intro</a>, classes and definitions
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000341(collectively known as 'records') in TableGen are the main high-level unit of
342information that TableGen collects. Records are defined with a <tt>def</tt> or
343<tt>class</tt> keyword, the record name, and an optional list of "<a
Misha Brukman179bf4b2004-06-03 23:42:24 +0000344href="#templateargs">template arguments</a>". If the record has superclasses,
Jeff Cohen0b81cda2005-10-24 16:54:55 +0000345they are specified as a comma separated list that starts with a colon character
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000346(":"). If <a href="#valuedef">value definitions</a> or <a href="#recordlet">let
John Criswellaa55c8c2004-02-12 18:11:53 +0000347expressions</a> are needed for the class, they are enclosed in curly braces
348("{}"); otherwise, the record ends with a semicolon. Here is a simple TableGen
Misha Brukman85234ac2004-05-12 18:31:21 +0000349file:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000350
Misha Brukman85234ac2004-05-12 18:31:21 +0000351<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000352<b>class</b> C { <b>bit</b> V = 1; }
353<b>def</b> X : C;
354<b>def</b> Y : C {
355 <b>string</b> Greeting = "hello";
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000356}
Misha Brukman85234ac2004-05-12 18:31:21 +0000357</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000358
Misha Brukman85234ac2004-05-12 18:31:21 +0000359<p>This example defines two definitions, <tt>X</tt> and <tt>Y</tt>, both of
360which derive from the <tt>C</tt> class. Because of this, they both get the
361<tt>V</tt> bit value. The <tt>Y</tt> definition also gets the Greeting member
362as well.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000363
Misha Brukman85234ac2004-05-12 18:31:21 +0000364<p>In general, classes are useful for collecting together the commonality
365between a group of records and isolating it in a single place. Also, classes
366permit the specification of default values for their subclasses, allowing the
367subclasses to override them as they wish.</p>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000368
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000369</div>
370
Misha Brukman85234ac2004-05-12 18:31:21 +0000371<!---------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000372<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000373 <a name="valuedef">Value definitions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000374</div>
375
376<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000377<p>Value definitions define named entries in records. A value must be defined
John Criswellaa55c8c2004-02-12 18:11:53 +0000378before it can be referred to as the operand for another value definition or
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000379before the value is reset with a <a href="#recordlet">let expression</a>. A
380value is defined by specifying a <a href="#types">TableGen type</a> and a name.
381If an initial value is available, it may be specified after the type with an
Misha Brukman85234ac2004-05-12 18:31:21 +0000382equal sign. Value definitions require terminating semicolons.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000383</div>
384
Misha Brukman85234ac2004-05-12 18:31:21 +0000385<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000386<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000387 <a name="recordlet">'let' expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000388</div>
389
390<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000391<p>A record-level let expression is used to change the value of a value
392definition in a record. This is primarily useful when a superclass defines a
393value that a derived class or definition wants to override. Let expressions
394consist of the '<tt>let</tt>' keyword followed by a value name, an equal sign
395("="), and a new value. For example, a new class could be added to the example
396above, redefining the <tt>V</tt> field for all of its subclasses:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000397
Misha Brukman85234ac2004-05-12 18:31:21 +0000398<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000399<b>class</b> D : C { let V = 0; }
400<b>def</b> Z : D;
Misha Brukman85234ac2004-05-12 18:31:21 +0000401</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000402
Misha Brukman85234ac2004-05-12 18:31:21 +0000403<p>In this case, the <tt>Z</tt> definition will have a zero value for its "V"
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000404value, despite the fact that it derives (indirectly) from the <tt>C</tt> class,
Misha Brukman85234ac2004-05-12 18:31:21 +0000405because the <tt>D</tt> class overrode its value.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000406
407</div>
408
Misha Brukman85234ac2004-05-12 18:31:21 +0000409<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000410<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000411 <a name="templateargs">Class template arguments</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000412</div>
413
414<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000415<p>TableGen permits the definition of parameterized classes as well as normal
Chris Lattner23f54fa2004-02-06 06:37:00 +0000416concrete classes. Parameterized TableGen classes specify a list of variable
417bindings (which may optionally have defaults) that are bound when used. Here is
418a simple example:</p>
419
Misha Brukman85234ac2004-05-12 18:31:21 +0000420<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000421<b>class</b> FPFormat&lt;<b>bits</b>&lt;3&gt; val&gt; {
422 <b>bits</b>&lt;3&gt; Value = val;
423}
424<b>def</b> NotFP : FPFormat&lt;0&gt;;
425<b>def</b> ZeroArgFP : FPFormat&lt;1&gt;;
426<b>def</b> OneArgFP : FPFormat&lt;2&gt;;
427<b>def</b> OneArgFPRW : FPFormat&lt;3&gt;;
428<b>def</b> TwoArgFP : FPFormat&lt;4&gt;;
429<b>def</b> SpecialFP : FPFormat&lt;5&gt;;
Misha Brukman85234ac2004-05-12 18:31:21 +0000430</pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000431
Misha Brukman85234ac2004-05-12 18:31:21 +0000432<p>In this case, template arguments are used as a space efficient way to specify
433a list of "enumeration values", each with a "Value" field set to the specified
Chris Lattner23f54fa2004-02-06 06:37:00 +0000434integer.</p>
435
436<p>The more esoteric forms of <a href="#values">TableGen expressions</a> are
437useful in conjunction with template arguments. As an example:</p>
438
Misha Brukman85234ac2004-05-12 18:31:21 +0000439<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000440<b>class</b> ModRefVal&lt;<b>bits</b>&lt;2&gt; val&gt; {
441 <b>bits</b>&lt;2&gt; Value = val;
442}
443
444<b>def</b> None : ModRefVal&lt;0&gt;;
445<b>def</b> Mod : ModRefVal&lt;1&gt;;
446<b>def</b> Ref : ModRefVal&lt;2&gt;;
447<b>def</b> ModRef : ModRefVal&lt;3&gt;;
448
449<b>class</b> Value&lt;ModRefVal MR&gt; {
450 <i>// decode some information into a more convenient format, while providing
451 // a nice interface to the user of the "Value" class.</i>
452 <b>bit</b> isMod = MR.Value{0};
453 <b>bit</b> isRef = MR.Value{1};
454
455 <i>// other stuff...</i>
456}
457
458<i>// Example uses</i>
459<b>def</b> bork : Value&lt;Mod&gt;;
460<b>def</b> zork : Value&lt;Ref&gt;;
461<b>def</b> hork : Value&lt;ModRef&gt;;
Misha Brukman85234ac2004-05-12 18:31:21 +0000462</pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000463
Misha Brukman85234ac2004-05-12 18:31:21 +0000464<p>This is obviously a contrived example, but it shows how template arguments
465can be used to decouple the interface provided to the user of the class from the
Chris Lattner23f54fa2004-02-06 06:37:00 +0000466actual internal data representation expected by the class. In this case,
467running <tt>tblgen</tt> on the example prints the following definitions:</p>
468
Misha Brukman85234ac2004-05-12 18:31:21 +0000469<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000470<b>def</b> bork { <i>// Value</i>
Chris Lattner84b35982006-09-01 21:44:18 +0000471 <b>bit</b> isMod = 1;
472 <b>bit</b> isRef = 0;
Chris Lattner23f54fa2004-02-06 06:37:00 +0000473}
474<b>def</b> hork { <i>// Value</i>
Chris Lattner84b35982006-09-01 21:44:18 +0000475 <b>bit</b> isMod = 1;
476 <b>bit</b> isRef = 1;
Chris Lattner23f54fa2004-02-06 06:37:00 +0000477}
478<b>def</b> zork { <i>// Value</i>
Chris Lattner84b35982006-09-01 21:44:18 +0000479 <b>bit</b> isMod = 0;
480 <b>bit</b> isRef = 1;
Chris Lattner23f54fa2004-02-06 06:37:00 +0000481}
Misha Brukman85234ac2004-05-12 18:31:21 +0000482</pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000483
Misha Brukman85234ac2004-05-12 18:31:21 +0000484<p> This shows that TableGen was able to dig into the argument and extract a
485piece of information that was requested by the designer of the "Value" class.
486For more realistic examples, please see existing users of TableGen, such as the
487X86 backend.</p>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000488
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000489</div>
490
Chris Lattner84b35982006-09-01 21:44:18 +0000491<!-- -------------------------------------------------------------------------->
492<div class="doc_subsubsection">
493 <a name="multiclass">Multiclass definitions and instances</a>
494</div>
495
496<div class="doc_text">
497
498<p>
499While classes with template arguments are a good way to factor commonality
500between two instances of a definition, multiclasses allow a convenient notation
501for defining multiple definitions at once (instances of implicitly constructed
502classes). For example, consider an 3-address instruction set whose instructions
503come in two forms: "reg = reg op reg" and "reg = reg op imm" (e.g. SPARC). In
504this case, you'd like to specify in one place that this commonality exists, then
505in a separate place indicate what all the ops are.
506</p>
507
508<p>
509Here is an example TableGen fragment that shows this idea:
510</p>
511
512<pre>
513<b>def</b> ops;
514<b>def</b> GPR;
515<b>def</b> Imm;
516<b>class</b> inst&lt;<b>int</b> opc, <b>string</b> asmstr, <b>dag</b> operandlist&gt;;
517
518<b>multiclass</b> ri_inst&lt;<b>int</b> opc, <b>string</b> asmstr&gt; {
519 def _rr : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
520 (ops GPR:$dst, GPR:$src1, GPR:$src2)&gt;;
521 def _ri : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
522 (ops GPR:$dst, GPR:$src1, Imm:$src2)&gt;;
523}
524
525// Instantiations of the ri_inst multiclass.
526<b>defm</b> ADD : ri_inst&lt;0b111, "add"&gt;;
527<b>defm</b> SUB : ri_inst&lt;0b101, "sub"&gt;;
528<b>defm</b> MUL : ri_inst&lt;0b100, "mul"&gt;;
529...
530</pre>
531
532<p>The name of the resuntant definitions has the multidef fragment names
533 appended to them, so this defines ADD_rr, ADD_ri, SUB_rr, etc. Using a
534 multiclass this way is exactly equivalent to instantiating the
535 classes multiple times yourself, e.g. by writing:</p>
536
537<pre>
538<b>def</b> ops;
539<b>def</b> GPR;
540<b>def</b> Imm;
541<b>class</b> inst&lt;<b>int</b> opc, <b>string</b> asmstr, <b>dag</b> operandlist&gt;;
542
543<b>class</b> rrinst&lt;<b>int</b> opc, <b>string</b> asmstr&gt;
544 : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
545 (ops GPR:$dst, GPR:$src1, GPR:$src2)&gt;;
546
547<b>class</b> riinst&lt;<b>int</b> opc, <b>string</b> asmstr&gt;
548 : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
549 (ops GPR:$dst, GPR:$src1, Imm:$src2)&gt;;
550
551// Instantiations of the ri_inst multiclass.
552<b>def</b> ADD_rr : rrinst&lt;0b111, "add"&gt;;
553<b>def</b> ADD_ri : riinst&lt;0b111, "add"&gt;;
554<b>def</b> SUB_rr : rrinst&lt;0b101, "sub"&gt;;
555<b>def</b> SUB_ri : riinst&lt;0b101, "sub"&gt;;
556<b>def</b> MUL_rr : rrinst&lt;0b100, "mul"&gt;;
557<b>def</b> MUL_ri : riinst&lt;0b100, "mul"&gt;;
558...
559</pre>
560
561</div>
562
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000563<!-- ======================================================================= -->
564<div class="doc_subsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000565 <a name="filescope">File scope entities</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000566</div>
567
Misha Brukman85234ac2004-05-12 18:31:21 +0000568<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000569<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000570 <a name="include">File inclusion</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000571</div>
572
573<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000574<p>TableGen supports the '<tt>include</tt>' token, which textually substitutes
575the specified file in place of the include directive. The filename should be
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000576specified as a double quoted string immediately after the '<tt>include</tt>'
Misha Brukman85234ac2004-05-12 18:31:21 +0000577keyword. Example:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000578
Misha Brukman85234ac2004-05-12 18:31:21 +0000579<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000580<b>include</b> "foo.td"
Misha Brukman85234ac2004-05-12 18:31:21 +0000581</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000582
583</div>
584
Misha Brukman85234ac2004-05-12 18:31:21 +0000585<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000586<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000587 <a name="globallet">'let' expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000588</div>
589
590<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000591<p> "let" expressions at file scope are similar to <a href="#recordlet">"let"
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000592expressions within a record</a>, except they can specify a value binding for
593multiple records at a time, and may be useful in certain other cases.
594File-scope let expressions are really just another way that TableGen allows the
Misha Brukman85234ac2004-05-12 18:31:21 +0000595end-user to factor out commonality from the records.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000596
Jeff Cohen0b81cda2005-10-24 16:54:55 +0000597<p>File-scope "let" expressions take a comma-separated list of bindings to
Misha Brukman85234ac2004-05-12 18:31:21 +0000598apply, and one of more records to bind the values in. Here are some
599examples:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000600
Misha Brukman85234ac2004-05-12 18:31:21 +0000601<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000602<b>let</b> isTerminator = 1, isReturn = 1 <b>in</b>
603 <b>def</b> RET : X86Inst&lt;"ret", 0xC3, RawFrm, NoArg&gt;;
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000604
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000605<b>let</b> isCall = 1 <b>in</b>
606 <i>// All calls clobber the non-callee saved registers...</i>
607 <b>let</b> Defs = [EAX, ECX, EDX, FP0, FP1, FP2, FP3, FP4, FP5, FP6] in {
608 <b>def</b> CALLpcrel32 : X86Inst&lt;"call", 0xE8, RawFrm, NoArg&gt;;
609 <b>def</b> CALLr32 : X86Inst&lt;"call", 0xFF, MRMS2r, Arg32&gt;;
610 <b>def</b> CALLm32 : X86Inst&lt;"call", 0xFF, MRMS2m, Arg32&gt;;
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000611 }
Misha Brukman85234ac2004-05-12 18:31:21 +0000612</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000613
Misha Brukman85234ac2004-05-12 18:31:21 +0000614<p>File-scope "let" expressions are often useful when a couple of definitions
615need to be added to several records, and the records do not otherwise need to be
616opened, as in the case with the CALL* instructions above.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000617</div>
618
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000619<!-- *********************************************************************** -->
620<div class="doc_section"><a name="backends">TableGen backends</a></div>
621<!-- *********************************************************************** -->
622
623<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000624<p>How they work, how to write one. This section should not contain details
625about any particular backend, except maybe -print-enums as an example. This
626should highlight the APIs in <tt>TableGen/Record.h</tt>.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000627</div>
628
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000629<!-- *********************************************************************** -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000630
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000631<hr>
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638 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
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