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8<body>
9
10<div class="doc_title">TableGen Fundamentals</div>
11
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]12<div class="doc_text">
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]13<ul>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]14 <li><a href="#introduction">Introduction</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]15 <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 +0000[diff] [blame^]19 </ol></li>
20 <li><a href="#syntax">TableGen syntax</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]21 <ol>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]22 <li><a href="#primitives">TableGen primitives</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]23 <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 +0000[diff] [blame^]27 </ol></li>
28 <li><a href="#classesdefs">Classes and definitions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]29 <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>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]33 </ol></li>
34 <li><a href="#filescope">File scope entities</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]35 <ol>
36 <li><a href="#include">File inclusion</a></li>
37 <li><a href="#globallet">'let' expressions</a></li>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]38 </ol></li>
39 </ol></li>
40 <li><a href="#backends">TableGen backends</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]41 <ol>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]42 <li><a href="#">todo</a></li>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]43 </ol></li>
44 <li><a href="#codegenerator">The LLVM code generator</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]45 <ol>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]46 <li><a href="#">todo</a></li>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]47 </ol></li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]48</ul>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]49</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]50
51<!-- *********************************************************************** -->
52<div class="doc_section"><a name="introduction">Introduction</a></div>
53<!-- *********************************************************************** -->
54
55<div class="doc_text">
56
57<p>TableGen's purpose is to help a human develop and maintain records of
58domain-specific information. Because there may be a large number of these
59records, it is specifically designed to allow writing flexible descriptions and
60for common features of these records to be factored out. This reduces the
61amount of duplication in the description, reduces the chance of error, and
62makes it easier to structure domain specific information.</p>
63
64<p>The core part of TableGen <a href="#syntax">parses a file</a>, instantiates
65the declarations, and hands the result off to a domain-specific "<a
66href="#backends">TableGen backend</a>" for processing. The current major user
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]67of TableGen is the <a href="#codegenerator">LLVM code generator</a>.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]68
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]69<p>Note that if you work on TableGen much, and use emacs or vim, that you can
70find an emacs "TableGen mode" and a vim language file in
71<tt>llvm/utils/emacs</tt> and <tt>llvm/utils/vim</tt> directory of your LLVM
72distribution, respectively.</p>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]73
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]74</div>
75
76<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]77<div class="doc_subsection"><a name="running">Basic concepts</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]78
79<div class="doc_text">
80
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]81<p>TableGen files consist of two key parts: 'classes' and 'definitions', both
82of which are considered 'records'.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]83
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]84<p><b>TableGen records</b> have a unique name, a list of values, and a list of
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]85superclasses. The list of values is main data that TableGen builds for each
86record, it is this that holds the domain specific information for the
87application. The interpretation of this data is left to a specific <a
88href="#backends">TableGen backend</a>, but the structure and format rules are
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]89taken care of and fixed by TableGen.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]90
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]91<p><b>TableGen definitions</b> are the concrete form of 'records'. These
92generally do not have any undefined values, and are marked with the
93'<tt>def</tt>' keyword.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]94
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]95<p><b>TableGen classes</b> are abstract records that are used to build and
96describe other records. These 'classes' allow the end-user to build
97abstractions for either the domain they are targetting (such as "Register",
98"RegisterClass", and "Instruction" in the LLVM code generator) or for the
99implementor to help factor out common properties of records (such as "FPInst",
100which is used to represent floating point instructions in the X86 backend).
101TableGen keeps track of all of the classes that are used to build up a
102definition, so the backend can find all definitions of a particular class, such
103as "Instruction".</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]104
105</div>
106
107<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]108<div class="doc_subsection"><a name="example">An example record</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]109
110<div class="doc_text">
111
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]112<p>With no other arguments, TableGen parses the specified file and prints out
113all of the classes, then all of the definitions. This is a good way to see what
114the various definitions expand to fully. Running this on the <tt>X86.td</tt>
115file prints this (at the time of this writing):</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]116
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]117<pre>
118...
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]119<b>def</b> ADDrr8 { <i>// Instruction X86Inst I2A8 Pattern</i>
120 <b>string</b> Name = "add";
121 <b>string</b> Namespace = "X86";
122 <b>list</b>&lt;Register&gt; Uses = [];
123 <b>list</b>&lt;Register&gt; Defs = [];
124 <b>bit</b> isReturn = 0;
125 <b>bit</b> isBranch = 0;
126 <b>bit</b> isCall = 0;
127 <b>bit</b> isTwoAddress = 1;
128 <b>bit</b> isTerminator = 0;
129 <b>dag</b> Pattern = (set R8, (plus R8, R8));
130 <b>bits</b>&lt;8&gt; Opcode = { 0, 0, 0, 0, 0, 0, 0, 0 };
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]131 Format Form = MRMDestReg;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]132 <b>bits</b>&lt;5&gt; FormBits = { 0, 0, 0, 1, 1 };
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]133 ArgType Type = Arg8;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]134 <b>bits</b>&lt;3&gt; TypeBits = { 0, 0, 1 };
135 <b>bit</b> hasOpSizePrefix = 0;
136 <b>bit</b> printImplicitUses = 0;
137 <b>bits</b>&lt;4&gt; Prefix = { 0, 0, 0, 0 };
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]138 FPFormat FPForm = ?;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]139 <b>bits</b>&lt;3&gt; FPFormBits = { 0, 0, 0 };
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]140}
141...
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]142</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]143
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]144<p>This definition corresponds to an 8-bit register-register add instruction in
145the X86. The string after the '<tt>def</tt>' string indicates the name of the
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]146record ("<tt>ADDrr8</tt>" in this case), and the comment at the end of the line
147indicates the superclasses of the definition. The body of the record contains
148all of the data that TableGen assembled for the record, indicating that the
149instruction is part of the "X86" namespace, should be printed as "<tt>add</tt>"
150in the assembly file, it is a two-address instruction, has a particular
151encoding, etc. The contents and semantics of the information in the record is
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]152specific to the needs of the X86 backend, and is only shown as an example.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]153
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]154<p>As you can see, a lot of information is needed for every instruction
155supported by the code generator, and specifying it all manually would be
156unmaintainble, prone to bugs, and tiring to do in the first place. Because we
157are using TableGen, all of the information was derived from the following
158definition:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]159
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]160<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]161<b>def</b> ADDrr8 : I2A8&lt;"add", 0x00, MRMDestReg&gt;,
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]162 Pattern&lt;(set R8, (plus R8, R8))&gt;;
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]163</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]164
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]165<p>This definition makes use of the custom I2A8 (two address instruction with
1668-bit operand) class, which is defined in the X86-specific TableGen file to
167factor out the common features that instructions of its class share. A key
168feature of TableGen is that it allows the end-user to define the abstractions
169they prefer to use when describing their information.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]170
171</div>
172
173<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]174<div class="doc_subsection"><a name="running">Running TableGen</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]175
176<div class="doc_text">
177
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]178<p>TableGen runs just like any other LLVM tool. The first (optional) argument
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]179specifies the file to read. If a filename is not specified, <tt>tblgen</tt>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]180reads from standard input.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]181
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]182<p>To be useful, one of the <a href="#backends">TableGen backends</a> must be
183used. These backends are selectable on the command line (type '<tt>tblgen
184--help</tt>' for a list). For example, to get a list of all of the definitions
185that subclass a particular type (which can be useful for building up an enum
186list of these records), use the <tt>--print-enums</tt> option:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]187
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]188<pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]189$ tblgen X86.td -print-enums -class=Register
190AH, AL, AX, BH, BL, BP, BX, CH, CL, CX, DH, DI, DL, DX,
191EAX, EBP, EBX, ECX, EDI, EDX, ESI, ESP, FP0, FP1, FP2, FP3, FP4, FP5, FP6,
192SI, SP, ST0, ST1, ST2, ST3, ST4, ST5, ST6, ST7,
193
194$ tblgen X86.td -print-enums -class=Instruction
195ADCrr32, ADDri16, ADDri16b, ADDri32, ADDri32b, ADDri8, ADDrr16, ADDrr32,
196ADDrr8, ADJCALLSTACKDOWN, ADJCALLSTACKUP, ANDri16, ANDri16b, ANDri32, ANDri32b,
197ANDri8, ANDrr16, ANDrr32, ANDrr8, BSWAPr32, CALLm32, CALLpcrel32, ...
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]198</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]199
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]200<p>The default backend prints out all of the records, as described <a
201href="#example">above</a>.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]202
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]203<p>If you plan to use TableGen for some purpose, you will most likely have to
204<a href="#backends">write a backend</a> that extracts the information specific
205to what you need and formats it in the appropriate way.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]206
207</div>
208
209
210<!-- *********************************************************************** -->
211<div class="doc_section"><a name="syntax">TableGen syntax</a></div>
212<!-- *********************************************************************** -->
213
214<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]215<p>TableGen doesn't care about the meaning of data (that is up to the backend
216to define), but it does care about syntax, and it enforces a simple type system.
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]217This section describes the syntax and the constructs allowed in a TableGen file.
218</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]219</div>
220
221<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]222<div class="doc_subsection"><a name="primitives">TableGen primitives</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]223
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]224<!-- -------------------------------------------------------------------------->
225<div class="doc_subsubsection"><a name="comments">TableGen comments</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]226
227<div class="doc_text">
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]228<p>TableGen supports BCPL style "<tt>//</tt>" comments, which run to the end of
229the line, and it also supports <b>nestable</b> "<tt>/* */</tt>" comments.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]230</div>
231
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]232<!-- -------------------------------------------------------------------------->
233<div class="doc_subsubsection"><a name="types">The TableGen type system</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]234</div>
235
236<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]237<p>TableGen files are strongly typed, in a simple (but complete) type-system.
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]238These types are used to perform automatic conversions, check for errors, and to
239help interface designers constrain the input that they allow. Every <a
240href="#valuedef">value definition</a> is required to have an associated type.
241</p>
242
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]243<p>TableGen supports a mixture of very low-level types (such as <tt>bit</tt>)
244and very high-level types (such as <tt>dag</tt>). This flexibility is what
245allows it to describe a wide range of information conveniently and compactly.
246The TableGen types are:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]247
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]248<ul>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]249<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 +0000[diff] [blame]2501.</li>
251
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]252<li>"<tt><b>int</b></tt>" - The 'int' type represents a simple 32-bit integer
253value, such as 5.</li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]254
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]255<li>"<tt><b>string</b></tt>" - The 'string' type represents an ordered sequence
256of characters of arbitrary length.</li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]257
John Criswellaa55c8c2004-02-12 18:11:53 +0000[diff] [blame]258<li>"<tt><b>bits</b>&lt;n&gt;</tt>" - A 'bits' type is an arbitrary, but fixed,
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]259size integer that is broken up into individual bits. This type is useful
260because it can handle some bits being defined while others are undefined.</li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]261
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]262<li>"<tt><b>list</b>&lt;ty&gt;</tt>" - This type represents a list whose
263elements are some other type. The contained type is arbitrary: it can even be
264another list type.</li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]265
266<li>Class type - Specifying a class name in a type context means that the
267defined value must be a subclass of the specified class. This is useful in
268conjunction with the "list" type, for example, to constrain the elements of the
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]269list to a common base class (e.g., a <tt><b>list</b>&lt;Register&gt;</tt> can
270only contain definitions derived from the "<tt>Register</tt>" class).</li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]271
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]272<li>"<tt><b>code</b></tt>" - This represents a big hunk of text. NOTE: I don't
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]273remember why this is distinct from string!</li>
274
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]275<li>"<tt><b>dag</b></tt>" - This type represents a nestable directed graph of
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]276elements.</li>
277</ul>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]278
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]279<p>To date, these types have been sufficient for describing things that
280TableGen has been used for, but it is straight-forward to extend this list if
281needed.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]282
283</div>
284
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]285<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]286<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]287 <a name="values">TableGen values and expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]288</div>
289
290<div>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]291<p>TableGen allows for a pretty reasonable number of different expression forms
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]292when building up values. These forms allow the TableGen file to be written in a
293natural syntax and flavor for the application. The current expression forms
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]294supported include:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]295
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]296<ul>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]297<li>? - Uninitialized field.</li>
298<li>0b1001011 - Binary integer value.</li>
299<li>07654321 - Octal integer value (indicated by a leading 0).</li>
300<li>7 - Decimal integer value.</li>
301<li>0x7F - Hexadecimal integer value.</li>
302<li>"foo" - String value.</li>
303<li>[{ .... }] - Code fragment.</li>
304<li>[ X, Y, Z ] - List value.</li>
305<li>{ a, b, c } - Initializer for a "bits&lt;3&gt;" value.</li>
306<li>value - Value reference.</li>
307<li>value{17} - Access to one or more bits of a value.</li>
308<li>DEF - Reference to a record definition.</li>
309<li>X.Y - Reference to the subfield of a value.</li>
310
311<li>(DEF a, b) - A dag value. The first element is required to be a record
312definition, the remaining elements in the list may be arbitrary other values,
313including nested 'dag' values.</li>
314
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]315</ul>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]316
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]317<p>Note that all of the values have rules specifying how they convert to values
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]318for different types. These rules allow you to assign a value like "7" to a
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]319"bits&lt;4&gt;" value, for example.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]320
321</div>
322
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]323<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]324<div class="doc_subsection"><a name="classesdefs">Classes and definitions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]325</div>
326
327<div>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]328<p>As mentioned in the <a href="#concepts">intro</a>, classes and definitions
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]329(collectively known as 'records') in TableGen are the main high-level unit of
330information that TableGen collects. Records are defined with a <tt>def</tt> or
331<tt>class</tt> keyword, the record name, and an optional list of "<a
332href="templateargs">template arguments</a>". If the record has superclasses,
333they are specified as a comma seperated list that starts with a colon character
334(":"). If <a href="#valuedef">value definitions</a> or <a href="#recordlet">let
John Criswellaa55c8c2004-02-12 18:11:53 +0000[diff] [blame]335expressions</a> are needed for the class, they are enclosed in curly braces
336("{}"); otherwise, the record ends with a semicolon. Here is a simple TableGen
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]337file:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]338
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]339<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]340<b>class</b> C { <b>bit</b> V = 1; }
341<b>def</b> X : C;
342<b>def</b> Y : C {
343 <b>string</b> Greeting = "hello";
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]344}
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]345</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]346
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]347<p>This example defines two definitions, <tt>X</tt> and <tt>Y</tt>, both of
348which derive from the <tt>C</tt> class. Because of this, they both get the
349<tt>V</tt> bit value. The <tt>Y</tt> definition also gets the Greeting member
350as well.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]351
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]352<p>In general, classes are useful for collecting together the commonality
353between a group of records and isolating it in a single place. Also, classes
354permit the specification of default values for their subclasses, allowing the
355subclasses to override them as they wish.</p>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]356
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]357</div>
358
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]359<!---------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]360<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]361 <a name="valuedef">Value definitions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]362</div>
363
364<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]365<p>Value definitions define named entries in records. A value must be defined
John Criswellaa55c8c2004-02-12 18:11:53 +0000[diff] [blame]366before it can be referred to as the operand for another value definition or
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]367before the value is reset with a <a href="#recordlet">let expression</a>. A
368value is defined by specifying a <a href="#types">TableGen type</a> and a name.
369If an initial value is available, it may be specified after the type with an
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]370equal sign. Value definitions require terminating semicolons.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]371</div>
372
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]373<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]374<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]375 <a name="recordlet">'let' expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]376</div>
377
378<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]379<p>A record-level let expression is used to change the value of a value
380definition in a record. This is primarily useful when a superclass defines a
381value that a derived class or definition wants to override. Let expressions
382consist of the '<tt>let</tt>' keyword followed by a value name, an equal sign
383("="), and a new value. For example, a new class could be added to the example
384above, redefining the <tt>V</tt> field for all of its subclasses:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]385
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]386<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]387<b>class</b> D : C { let V = 0; }
388<b>def</b> Z : D;
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]389</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]390
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]391<p>In this case, the <tt>Z</tt> definition will have a zero value for its "V"
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]392value, despite the fact that it derives (indirectly) from the <tt>C</tt> class,
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]393because the <tt>D</tt> class overrode its value.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]394
395</div>
396
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]397<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]398<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]399 <a name="templateargs">Class template arguments</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]400</div>
401
402<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]403<p>TableGen permits the definition of parameterized classes as well as normal
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]404concrete classes. Parameterized TableGen classes specify a list of variable
405bindings (which may optionally have defaults) that are bound when used. Here is
406a simple example:</p>
407
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]408<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]409<b>class</b> FPFormat&lt;<b>bits</b>&lt;3&gt; val&gt; {
410 <b>bits</b>&lt;3&gt; Value = val;
411}
412<b>def</b> NotFP : FPFormat&lt;0&gt;;
413<b>def</b> ZeroArgFP : FPFormat&lt;1&gt;;
414<b>def</b> OneArgFP : FPFormat&lt;2&gt;;
415<b>def</b> OneArgFPRW : FPFormat&lt;3&gt;;
416<b>def</b> TwoArgFP : FPFormat&lt;4&gt;;
417<b>def</b> SpecialFP : FPFormat&lt;5&gt;;
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]418</pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]419
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]420<p>In this case, template arguments are used as a space efficient way to specify
421a list of "enumeration values", each with a "Value" field set to the specified
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]422integer.</p>
423
424<p>The more esoteric forms of <a href="#values">TableGen expressions</a> are
425useful in conjunction with template arguments. As an example:</p>
426
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]427<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]428<b>class</b> ModRefVal&lt;<b>bits</b>&lt;2&gt; val&gt; {
429 <b>bits</b>&lt;2&gt; Value = val;
430}
431
432<b>def</b> None : ModRefVal&lt;0&gt;;
433<b>def</b> Mod : ModRefVal&lt;1&gt;;
434<b>def</b> Ref : ModRefVal&lt;2&gt;;
435<b>def</b> ModRef : ModRefVal&lt;3&gt;;
436
437<b>class</b> Value&lt;ModRefVal MR&gt; {
438 <i>// decode some information into a more convenient format, while providing
439 // a nice interface to the user of the "Value" class.</i>
440 <b>bit</b> isMod = MR.Value{0};
441 <b>bit</b> isRef = MR.Value{1};
442
443 <i>// other stuff...</i>
444}
445
446<i>// Example uses</i>
447<b>def</b> bork : Value&lt;Mod&gt;;
448<b>def</b> zork : Value&lt;Ref&gt;;
449<b>def</b> hork : Value&lt;ModRef&gt;;
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]450</pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]451
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]452<p>This is obviously a contrived example, but it shows how template arguments
453can be used to decouple the interface provided to the user of the class from the
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]454actual internal data representation expected by the class. In this case,
455running <tt>tblgen</tt> on the example prints the following definitions:</p>
456
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]457<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]458<b>def</b> bork { <i>// Value</i>
459 bit isMod = 1;
460 bit isRef = 0;
461}
462<b>def</b> hork { <i>// Value</i>
463 bit isMod = 1;
464 bit isRef = 1;
465}
466<b>def</b> zork { <i>// Value</i>
467 bit isMod = 0;
468 bit isRef = 1;
469}
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]470</pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]471
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]472<p> This shows that TableGen was able to dig into the argument and extract a
473piece of information that was requested by the designer of the "Value" class.
474For more realistic examples, please see existing users of TableGen, such as the
475X86 backend.</p>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]476
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]477</div>
478
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]479<!-- ======================================================================= -->
480<div class="doc_subsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]481 <a name="filescope">File scope entities</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]482</div>
483
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]484<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]485<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]486 <a name="include">File inclusion</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]487</div>
488
489<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]490<p>TableGen supports the '<tt>include</tt>' token, which textually substitutes
491the specified file in place of the include directive. The filename should be
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]492specified as a double quoted string immediately after the '<tt>include</tt>'
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]493keyword. Example:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]494
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]495<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]496<b>include</b> "foo.td"
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]497</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]498
499</div>
500
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]501<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]502<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]503 <a name="globallet">'let' expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]504</div>
505
506<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]507<p> "let" expressions at file scope are similar to <a href="#recordlet">"let"
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]508expressions within a record</a>, except they can specify a value binding for
509multiple records at a time, and may be useful in certain other cases.
510File-scope let expressions are really just another way that TableGen allows the
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]511end-user to factor out commonality from the records.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]512
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]513<p>File-scope "let" expressions take a comma-seperated list of bindings to
514apply, and one of more records to bind the values in. Here are some
515examples:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]516
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]517<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]518<b>let</b> isTerminator = 1, isReturn = 1 <b>in</b>
519 <b>def</b> RET : X86Inst&lt;"ret", 0xC3, RawFrm, NoArg&gt;;
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]520
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]521<b>let</b> isCall = 1 <b>in</b>
522 <i>// All calls clobber the non-callee saved registers...</i>
523 <b>let</b> Defs = [EAX, ECX, EDX, FP0, FP1, FP2, FP3, FP4, FP5, FP6] in {
524 <b>def</b> CALLpcrel32 : X86Inst&lt;"call", 0xE8, RawFrm, NoArg&gt;;
525 <b>def</b> CALLr32 : X86Inst&lt;"call", 0xFF, MRMS2r, Arg32&gt;;
526 <b>def</b> CALLm32 : X86Inst&lt;"call", 0xFF, MRMS2m, Arg32&gt;;
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]527 }
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]528</pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]529
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]530<p>File-scope "let" expressions are often useful when a couple of definitions
531need to be added to several records, and the records do not otherwise need to be
532opened, as in the case with the CALL* instructions above.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]533</div>
534
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]535<!-- *********************************************************************** -->
536<div class="doc_section"><a name="backends">TableGen backends</a></div>
537<!-- *********************************************************************** -->
538
539<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]540<p>How they work, how to write one. This section should not contain details
541about any particular backend, except maybe -print-enums as an example. This
542should highlight the APIs in <tt>TableGen/Record.h</tt>.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]543</div>
544
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]545<!-- *********************************************************************** -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]546<div class="doc_section"><a name="codegenerator">The LLVM code generator</a>
547</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]548<!-- *********************************************************************** -->
549
550<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]551<p>This is just a temporary, convenient, place to put stuff about the code
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]552generator before it gets its own document. This should describe all of the
553tablegen backends used by the code generator and the classes/definitions they
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]554expect.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]555</div>
556
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]557<!-- *********************************************************************** -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]558
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]559<hr>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]560<address>
561 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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565
566 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
567 <a href="http://llvm.cs.uiuc.edu">LLVM Compiler Infrastructure</a><br>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]568 Last modified: $Date$
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame^]569</address>
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