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4<head>
5 <title>TableGen Fundamentals</title>
6 <link rel="stylesheet" href="llvm.css" type="text/css">
7</head>
8<body>
9
10<div class="doc_title">TableGen Fundamentals</div>
11
12<div class="doc_text">
13<ul>
14 <li><a href="#introduction">Introduction</a>
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>
19 </ol></li>
20 <li><a href="#syntax">TableGen syntax</a>
21 <ol>
22 <li><a href="#primitives">TableGen primitives</a>
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>
27 </ol></li>
28 <li><a href="#classesdefs">Classes and definitions</a>
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>
33 <li><a href="#multiclass">Multiclass definitions and instances</a></li>
34 </ol></li>
35 <li><a href="#filescope">File scope entities</a>
36 <ol>
37 <li><a href="#include">File inclusion</a></li>
38 <li><a href="#globallet">'let' expressions</a></li>
39 </ol></li>
40 </ol></li>
41 <li><a href="#backends">TableGen backends</a>
42 <ol>
43 <li><a href="#">todo</a></li>
44 </ol></li>
45</ul>
46</div>
47
48<div class="doc_author">
49 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></p>
50</div>
51
52<!-- *********************************************************************** -->
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
68of TableGen is the <a href="CodeGenerator.html">LLVM code generator</a>.</p>
69
70<p>Note that if you work on TableGen much, and use emacs or vim, that you can
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]71find an emacs "TableGen mode" and a vim language file in the
72<tt>llvm/utils/emacs</tt> and <tt>llvm/utils/vim</tt> directories of your LLVM
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]73distribution, respectively.</p>
74
75</div>
76
77<!-- ======================================================================= -->
78<div class="doc_subsection"><a name="concepts">Basic concepts</a></div>
79
80<div class="doc_text">
81
82<p>TableGen files consist of two key parts: 'classes' and 'definitions', both
83of which are considered 'records'.</p>
84
85<p><b>TableGen records</b> have a unique name, a list of values, and a list of
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]86superclasses. The list of values is the main data that TableGen builds for each
87record; it is this that holds the domain specific information for the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]88application. The interpretation of this data is left to a specific <a
89href="#backends">TableGen backend</a>, but the structure and format rules are
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]90taken care of and are fixed by TableGen.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]91
92<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>
95
96<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
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]98abstractions for either the domain they are targeting (such as "Register",
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]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>
105
106<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
110</div>
111
112<!-- ======================================================================= -->
113<div class="doc_subsection"><a name="example">An example record</a></div>
114
115<div class="doc_text">
116
117<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>
121
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]122<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]123<pre>
124...
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]125<b>def</b> ADD32rr { <i>// Instruction X86Inst I</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]126 <b>string</b> Namespace = "X86";
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]127 <b>dag</b> OutOperandList = (outs GR32:$dst);
128 <b>dag</b> InOperandList = (ins GR32:$src1, GR32:$src2);
129 <b>string</b> AsmString = "add{l}\t{$src2, $dst|$dst, $src2}";
130 <b>list</b>&lt;dag&gt; Pattern = [(set GR32:$dst, (add GR32:$src1, GR32:$src2))];
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]131 <b>list</b>&lt;Register&gt; Uses = [];
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]132 <b>list</b>&lt;Register&gt; Defs = [EFLAGS];
133 <b>list</b>&lt;Predicate&gt; Predicates = [];
134 <b>int</b> CodeSize = 3;
135 <b>int</b> AddedComplexity = 0;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]136 <b>bit</b> isReturn = 0;
137 <b>bit</b> isBranch = 0;
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]138 <b>bit</b> isIndirectBranch = 0;
139 <b>bit</b> isBarrier = 0;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]140 <b>bit</b> isCall = 0;
Dan Gohman5574cc72008-12-03 18:15:48 +0000[diff] [blame]141 <b>bit</b> canFoldAsLoad = 0;
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]142 <b>bit</b> mayLoad = 0;
143 <b>bit</b> mayStore = 0;
144 <b>bit</b> isImplicitDef = 0;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]145 <b>bit</b> isTwoAddress = 1;
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]146 <b>bit</b> isConvertibleToThreeAddress = 1;
147 <b>bit</b> isCommutable = 1;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]148 <b>bit</b> isTerminator = 0;
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]149 <b>bit</b> isReMaterializable = 0;
150 <b>bit</b> isPredicable = 0;
151 <b>bit</b> hasDelaySlot = 0;
152 <b>bit</b> usesCustomDAGSchedInserter = 0;
153 <b>bit</b> hasCtrlDep = 0;
154 <b>bit</b> isNotDuplicable = 0;
155 <b>bit</b> hasSideEffects = 0;
156 <b>bit</b> mayHaveSideEffects = 0;
157 <b>bit</b> neverHasSideEffects = 0;
158 InstrItinClass Itinerary = NoItinerary;
159 <b>string</b> Constraints = "";
160 <b>string</b> DisableEncoding = "";
161 <b>bits</b>&lt;8&gt; Opcode = { 0, 0, 0, 0, 0, 0, 0, 1 };
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]162 Format Form = MRMDestReg;
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]163 <b>bits</b>&lt;6&gt; FormBits = { 0, 0, 0, 0, 1, 1 };
164 ImmType ImmT = NoImm;
165 <b>bits</b>&lt;3&gt; ImmTypeBits = { 0, 0, 0 };
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]166 <b>bit</b> hasOpSizePrefix = 0;
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]167 <b>bit</b> hasAdSizePrefix = 0;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]168 <b>bits</b>&lt;4&gt; Prefix = { 0, 0, 0, 0 };
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]169 <b>bit</b> hasREX_WPrefix = 0;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]170 FPFormat FPForm = ?;
171 <b>bits</b>&lt;3&gt; FPFormBits = { 0, 0, 0 };
172}
173...
174</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]175</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]176
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]177<p>This definition corresponds to a 32-bit register-register add instruction in
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]178the X86. The string after the '<tt>def</tt>' string indicates the name of the
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]179record&mdash;"<tt>ADD32rr</tt>" in this case&mdash;and the comment at the end of
180the line indicates the superclasses of the definition. The body of the record
181contains all of the data that TableGen assembled for the record, indicating that
182the instruction is part of the "X86" namespace, the pattern indicating how the
183the instruction should be emitted into the assembly file, that it is a
184two-address instruction, has a particular encoding, etc. The contents and
185semantics of the information in the record is specific to the needs of the X86
186backend, and is only shown as an example.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]187
188<p>As you can see, a lot of information is needed for every instruction
189supported by the code generator, and specifying it all manually would be
190unmaintainble, prone to bugs, and tiring to do in the first place. Because we
191are using TableGen, all of the information was derived from the following
192definition:</p>
193
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]194<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]195<pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]196let Defs = [EFLAGS],
197 isCommutable = 1, <i>// X = ADD Y,Z --&gt; X = ADD Z,Y</i>
198 isConvertibleToThreeAddress = 1 <b>in</b> <i>// Can transform into LEA.</i>
199def ADD32rr : I&lt;0x01, MRMDestReg, (outs GR32:$dst),
200 (ins GR32:$src1, GR32:$src2),
201 "add{l}\t{$src2, $dst|$dst, $src2}",
202 [(set GR32:$dst, (add GR32:$src1, GR32:$src2))]&gt;;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]203</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]204</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]205
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]206<p>This definition makes use of the custom class <tt>I</tt> (extended from the
207custom class <tt>X86Inst</tt>), which is defined in the X86-specific TableGen
208file, to factor out the common features that instructions of its class share. A
209key feature of TableGen is that it allows the end-user to define the
210abstractions they prefer to use when describing their information.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]211
212</div>
213
214<!-- ======================================================================= -->
215<div class="doc_subsection"><a name="running">Running TableGen</a></div>
216
217<div class="doc_text">
218
219<p>TableGen runs just like any other LLVM tool. The first (optional) argument
220specifies the file to read. If a filename is not specified, <tt>tblgen</tt>
221reads from standard input.</p>
222
223<p>To be useful, one of the <a href="#backends">TableGen backends</a> must be
224used. These backends are selectable on the command line (type '<tt>tblgen
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]225-help</tt>' for a list). For example, to get a list of all of the definitions
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]226that subclass a particular type (which can be useful for building up an enum
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]227list of these records), use the <tt>-print-enums</tt> option:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]228
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]229<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]230<pre>
231$ tblgen X86.td -print-enums -class=Register
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]232AH, AL, AX, BH, BL, BP, BPL, BX, CH, CL, CX, DH, DI, DIL, DL, DX, EAX, EBP, EBX,
233ECX, EDI, EDX, EFLAGS, EIP, ESI, ESP, FP0, FP1, FP2, FP3, FP4, FP5, FP6, IP,
234MM0, MM1, MM2, MM3, MM4, MM5, MM6, MM7, R10, R10B, R10D, R10W, R11, R11B, R11D,
235R11W, R12, R12B, R12D, R12W, R13, R13B, R13D, R13W, R14, R14B, R14D, R14W, R15,
236R15B, R15D, R15W, R8, R8B, R8D, R8W, R9, R9B, R9D, R9W, RAX, RBP, RBX, RCX, RDI,
237RDX, RIP, RSI, RSP, SI, SIL, SP, SPL, ST0, ST1, ST2, ST3, ST4, ST5, ST6, ST7,
238XMM0, XMM1, XMM10, XMM11, XMM12, XMM13, XMM14, XMM15, XMM2, XMM3, XMM4, XMM5,
239XMM6, XMM7, XMM8, XMM9,
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]240
241$ tblgen X86.td -print-enums -class=Instruction
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]242ABS_F, ABS_Fp32, ABS_Fp64, ABS_Fp80, ADC32mi, ADC32mi8, ADC32mr, ADC32ri,
243ADC32ri8, ADC32rm, ADC32rr, ADC64mi32, ADC64mi8, ADC64mr, ADC64ri32, ADC64ri8,
244ADC64rm, ADC64rr, ADD16mi, ADD16mi8, ADD16mr, ADD16ri, ADD16ri8, ADD16rm,
245ADD16rr, ADD32mi, ADD32mi8, ADD32mr, ADD32ri, ADD32ri8, ADD32rm, ADD32rr,
246ADD64mi32, ADD64mi8, ADD64mr, ADD64ri32, ...
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]247</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]248</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]249
250<p>The default backend prints out all of the records, as described <a
251href="#example">above</a>.</p>
252
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]253<p>If you plan to use TableGen, you will most likely have to <a
254href="#backends">write a backend</a> that extracts the information specific to
255what you need and formats it in the appropriate way.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]256
257</div>
258
259
260<!-- *********************************************************************** -->
261<div class="doc_section"><a name="syntax">TableGen syntax</a></div>
262<!-- *********************************************************************** -->
263
264<div class="doc_text">
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]265
266<p>TableGen doesn't care about the meaning of data (that is up to the backend to
267define), but it does care about syntax, and it enforces a simple type system.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]268This section describes the syntax and the constructs allowed in a TableGen file.
269</p>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]270
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]271</div>
272
273<!-- ======================================================================= -->
274<div class="doc_subsection"><a name="primitives">TableGen primitives</a></div>
275
276<!-- -------------------------------------------------------------------------->
277<div class="doc_subsubsection"><a name="comments">TableGen comments</a></div>
278
279<div class="doc_text">
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]280
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]281<p>TableGen supports BCPL style "<tt>//</tt>" comments, which run to the end of
282the line, and it also supports <b>nestable</b> "<tt>/* */</tt>" comments.</p>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]283
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]284</div>
285
286<!-- -------------------------------------------------------------------------->
287<div class="doc_subsubsection">
288 <a name="types">The TableGen type system</a>
289</div>
290
291<div class="doc_text">
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]292
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]293<p>TableGen files are strongly typed, in a simple (but complete) type-system.
294These types are used to perform automatic conversions, check for errors, and to
295help interface designers constrain the input that they allow. Every <a
296href="#valuedef">value definition</a> is required to have an associated type.
297</p>
298
299<p>TableGen supports a mixture of very low-level types (such as <tt>bit</tt>)
300and very high-level types (such as <tt>dag</tt>). This flexibility is what
301allows it to describe a wide range of information conveniently and compactly.
302The TableGen types are:</p>
303
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]304<dl>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]305<dt><tt><b>bit</b></tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]306 <dd>A 'bit' is a boolean value that can hold either 0 or 1.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]307
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]308<dt><tt><b>int</b></tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]309 <dd>The 'int' type represents a simple 32-bit integer value, such as 5.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]310
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]311<dt><tt><b>string</b></tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]312 <dd>The 'string' type represents an ordered sequence of characters of
313 arbitrary length.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]314
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]315<dt><tt><b>bits</b>&lt;n&gt;</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]316 <dd>A 'bits' type is an arbitrary, but fixed, size integer that is broken up
317 into individual bits. This type is useful because it can handle some bits
318 being defined while others are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]319
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]320<dt><tt><b>list</b>&lt;ty&gt;</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]321 <dd>This type represents a list whose elements are some other type. The
322 contained type is arbitrary: it can even be another list type.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]323
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]324<dt>Class type</dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]325 <dd>Specifying a class name in a type context means that the defined value
326 must be a subclass of the specified class. This is useful in conjunction with
327 the <b><tt>list</tt></b> type, for example, to constrain the elements of the
328 list to a common base class (e.g., a <tt><b>list</b>&lt;Register&gt;</tt> can
329 only contain definitions derived from the "<tt>Register</tt>" class).</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]330
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]331<dt><tt><b>dag</b></tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]332 <dd>This type represents a nestable directed graph of elements.</dd>
333
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]334<dt><tt><b>code</b></tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]335 <dd>This represents a big hunk of text. NOTE: I don't remember why this is
336 distinct from string!</dd>
337</dl>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]338
339<p>To date, these types have been sufficient for describing things that
340TableGen has been used for, but it is straight-forward to extend this list if
341needed.</p>
342
343</div>
344
345<!-- -------------------------------------------------------------------------->
346<div class="doc_subsubsection">
347 <a name="values">TableGen values and expressions</a>
348</div>
349
350<div class="doc_text">
351
352<p>TableGen allows for a pretty reasonable number of different expression forms
353when building up values. These forms allow the TableGen file to be written in a
354natural syntax and flavor for the application. The current expression forms
355supported include:</p>
356
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]357<dl>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]358<dt><tt>?</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]359 <dd>uninitialized field</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]360<dt><tt>0b1001011</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]361 <dd>binary integer value</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]362<dt><tt>07654321</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]363 <dd>octal integer value (indicated by a leading 0)</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]364<dt><tt>7</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]365 <dd>decimal integer value</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]366<dt><tt>0x7F</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]367 <dd>hexadecimal integer value</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]368<dt><tt>"foo"</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]369 <dd>string value</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]370<dt><tt>[{ ... }]</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]371 <dd>code fragment</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]372<dt><tt>[ X, Y, Z ]</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]373 <dd>list value.</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]374<dt><tt>{ a, b, c }</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]375 <dd>initializer for a "bits&lt;3&gt;" value</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]376<dt><tt>value</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]377 <dd>value reference</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]378<dt><tt>value{17}</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]379 <dd>access to one bit of a value</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]380<dt><tt>value{15-17}</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]381 <dd>access to multiple bits of a value</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]382<dt><tt>DEF</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]383 <dd>reference to a record definition</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]384<dt><tt>CLASS&lt;val list&gt;</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]385 <dd>reference to a new anonymous definition of CLASS with the specified
386 template arguments.</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]387<dt><tt>X.Y</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]388 <dd>reference to the subfield of a value</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]389<dt><tt>list[4-7,17,2-3]</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]390 <dd>A slice of the 'list' list, including elements 4,5,6,7,17,2, and 3 from
391 it. Elements may be included multiple times.</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]392<dt><tt>(DEF a, b)</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]393 <dd>a dag value. The first element is required to be a record definition, the
394 remaining elements in the list may be arbitrary other values, including nested
395 `<tt>dag</tt>' values.</dd>
Bill Wendlingd5f12012008-02-12 07:09:05 +0000[diff] [blame]396<dt><tt>!strconcat(a, b)</tt></dt>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]397 <dd>A string value that is the result of concatenating the 'a' and 'b'
398 strings.</dd>
399</dl>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]400
401<p>Note that all of the values have rules specifying how they convert to values
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]402for different types. These rules allow you to assign a value like "<tt>7</tt>"
403to a "<tt>bits&lt;4&gt;</tt>" value, for example.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]404
405</div>
406
407<!-- ======================================================================= -->
408<div class="doc_subsection">
409 <a name="classesdefs">Classes and definitions</a>
410</div>
411
412<div class="doc_text">
413
414<p>As mentioned in the <a href="#concepts">intro</a>, classes and definitions
415(collectively known as 'records') in TableGen are the main high-level unit of
416information that TableGen collects. Records are defined with a <tt>def</tt> or
417<tt>class</tt> keyword, the record name, and an optional list of "<a
418href="#templateargs">template arguments</a>". If the record has superclasses,
419they are specified as a comma separated list that starts with a colon character
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]420("<tt>:</tt>"). If <a href="#valuedef">value definitions</a> or <a
421href="#recordlet">let expressions</a> are needed for the class, they are
422enclosed in curly braces ("<tt>{}</tt>"); otherwise, the record ends with a
423semicolon.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]424
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]425<p>Here is a simple TableGen file:</p>
426
427<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]428<pre>
429<b>class</b> C { <b>bit</b> V = 1; }
430<b>def</b> X : C;
431<b>def</b> Y : C {
432 <b>string</b> Greeting = "hello";
433}
434</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]435</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]436
437<p>This example defines two definitions, <tt>X</tt> and <tt>Y</tt>, both of
438which derive from the <tt>C</tt> class. Because of this, they both get the
439<tt>V</tt> bit value. The <tt>Y</tt> definition also gets the Greeting member
440as well.</p>
441
442<p>In general, classes are useful for collecting together the commonality
443between a group of records and isolating it in a single place. Also, classes
444permit the specification of default values for their subclasses, allowing the
445subclasses to override them as they wish.</p>
446
447</div>
448
449<!---------------------------------------------------------------------------->
450<div class="doc_subsubsection">
451 <a name="valuedef">Value definitions</a>
452</div>
453
454<div class="doc_text">
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]455
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]456<p>Value definitions define named entries in records. A value must be defined
457before it can be referred to as the operand for another value definition or
458before the value is reset with a <a href="#recordlet">let expression</a>. A
459value is defined by specifying a <a href="#types">TableGen type</a> and a name.
460If an initial value is available, it may be specified after the type with an
461equal sign. Value definitions require terminating semicolons.</p>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]462
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]463</div>
464
465<!-- -------------------------------------------------------------------------->
466<div class="doc_subsubsection">
467 <a name="recordlet">'let' expressions</a>
468</div>
469
470<div class="doc_text">
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]471
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]472<p>A record-level let expression is used to change the value of a value
473definition in a record. This is primarily useful when a superclass defines a
474value that a derived class or definition wants to override. Let expressions
475consist of the '<tt>let</tt>' keyword followed by a value name, an equal sign
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]476("<tt>=</tt>"), and a new value. For example, a new class could be added to the
477example above, redefining the <tt>V</tt> field for all of its subclasses:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]478
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]479<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]480<pre>
481<b>class</b> D : C { let V = 0; }
482<b>def</b> Z : D;
483</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]484</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]485
486<p>In this case, the <tt>Z</tt> definition will have a zero value for its "V"
487value, despite the fact that it derives (indirectly) from the <tt>C</tt> class,
488because the <tt>D</tt> class overrode its value.</p>
489
490</div>
491
492<!-- -------------------------------------------------------------------------->
493<div class="doc_subsubsection">
494 <a name="templateargs">Class template arguments</a>
495</div>
496
497<div class="doc_text">
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]498
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]499<p>TableGen permits the definition of parameterized classes as well as normal
500concrete classes. Parameterized TableGen classes specify a list of variable
501bindings (which may optionally have defaults) that are bound when used. Here is
502a simple example:</p>
503
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]504<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]505<pre>
506<b>class</b> FPFormat&lt;<b>bits</b>&lt;3&gt; val&gt; {
507 <b>bits</b>&lt;3&gt; Value = val;
508}
509<b>def</b> NotFP : FPFormat&lt;0&gt;;
510<b>def</b> ZeroArgFP : FPFormat&lt;1&gt;;
511<b>def</b> OneArgFP : FPFormat&lt;2&gt;;
512<b>def</b> OneArgFPRW : FPFormat&lt;3&gt;;
513<b>def</b> TwoArgFP : FPFormat&lt;4&gt;;
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]514<b>def</b> CompareFP : FPFormat&lt;5&gt;;
515<b>def</b> CondMovFP : FPFormat&lt;6&gt;;
516<b>def</b> SpecialFP : FPFormat&lt;7&gt;;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]517</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]518</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]519
520<p>In this case, template arguments are used as a space efficient way to specify
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]521a list of "enumeration values", each with a "<tt>Value</tt>" field set to the
522specified integer.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]523
524<p>The more esoteric forms of <a href="#values">TableGen expressions</a> are
525useful in conjunction with template arguments. As an example:</p>
526
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]527<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]528<pre>
529<b>class</b> ModRefVal&lt;<b>bits</b>&lt;2&gt; val&gt; {
530 <b>bits</b>&lt;2&gt; Value = val;
531}
532
533<b>def</b> None : ModRefVal&lt;0&gt;;
534<b>def</b> Mod : ModRefVal&lt;1&gt;;
535<b>def</b> Ref : ModRefVal&lt;2&gt;;
536<b>def</b> ModRef : ModRefVal&lt;3&gt;;
537
538<b>class</b> Value&lt;ModRefVal MR&gt; {
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]539 <i>// Decode some information into a more convenient format, while providing
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]540 // a nice interface to the user of the "Value" class.</i>
541 <b>bit</b> isMod = MR.Value{0};
542 <b>bit</b> isRef = MR.Value{1};
543
544 <i>// other stuff...</i>
545}
546
547<i>// Example uses</i>
548<b>def</b> bork : Value&lt;Mod&gt;;
549<b>def</b> zork : Value&lt;Ref&gt;;
550<b>def</b> hork : Value&lt;ModRef&gt;;
551</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]552</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]553
554<p>This is obviously a contrived example, but it shows how template arguments
555can be used to decouple the interface provided to the user of the class from the
556actual internal data representation expected by the class. In this case,
557running <tt>tblgen</tt> on the example prints the following definitions:</p>
558
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]559<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]560<pre>
561<b>def</b> bork { <i>// Value</i>
562 <b>bit</b> isMod = 1;
563 <b>bit</b> isRef = 0;
564}
565<b>def</b> hork { <i>// Value</i>
566 <b>bit</b> isMod = 1;
567 <b>bit</b> isRef = 1;
568}
569<b>def</b> zork { <i>// Value</i>
570 <b>bit</b> isMod = 0;
571 <b>bit</b> isRef = 1;
572}
573</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]574</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]575
576<p> This shows that TableGen was able to dig into the argument and extract a
577piece of information that was requested by the designer of the "Value" class.
578For more realistic examples, please see existing users of TableGen, such as the
579X86 backend.</p>
580
581</div>
582
583<!-- -------------------------------------------------------------------------->
584<div class="doc_subsubsection">
585 <a name="multiclass">Multiclass definitions and instances</a>
586</div>
587
588<div class="doc_text">
589
590<p>
591While classes with template arguments are a good way to factor commonality
592between two instances of a definition, multiclasses allow a convenient notation
593for defining multiple definitions at once (instances of implicitly constructed
594classes). For example, consider an 3-address instruction set whose instructions
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]595come in two forms: "<tt>reg = reg op reg</tt>" and "<tt>reg = reg op imm</tt>"
596(e.g. SPARC). In this case, you'd like to specify in one place that this
597commonality exists, then in a separate place indicate what all the ops are.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]598</p>
599
600<p>
601Here is an example TableGen fragment that shows this idea:
602</p>
603
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]604<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]605<pre>
606<b>def</b> ops;
607<b>def</b> GPR;
608<b>def</b> Imm;
609<b>class</b> inst&lt;<b>int</b> opc, <b>string</b> asmstr, <b>dag</b> operandlist&gt;;
610
611<b>multiclass</b> ri_inst&lt;<b>int</b> opc, <b>string</b> asmstr&gt; {
612 def _rr : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
613 (ops GPR:$dst, GPR:$src1, GPR:$src2)&gt;;
614 def _ri : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
615 (ops GPR:$dst, GPR:$src1, Imm:$src2)&gt;;
616}
617
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]618<i>// Instantiations of the ri_inst multiclass.</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]619<b>defm</b> ADD : ri_inst&lt;0b111, "add"&gt;;
620<b>defm</b> SUB : ri_inst&lt;0b101, "sub"&gt;;
621<b>defm</b> MUL : ri_inst&lt;0b100, "mul"&gt;;
622...
623</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]624</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]625
626<p>The name of the resultant definitions has the multidef fragment names
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]627 appended to them, so this defines <tt>ADD_rr</tt>, <tt>ADD_ri</tt>,
628 <tt>SUB_rr</tt>, etc. Using a multiclass this way is exactly equivalent to
629 instantiating the classes multiple times yourself, e.g. by writing:</p>
630
631<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]632<pre>
633<b>def</b> ops;
634<b>def</b> GPR;
635<b>def</b> Imm;
636<b>class</b> inst&lt;<b>int</b> opc, <b>string</b> asmstr, <b>dag</b> operandlist&gt;;
637
638<b>class</b> rrinst&lt;<b>int</b> opc, <b>string</b> asmstr&gt;
639 : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
640 (ops GPR:$dst, GPR:$src1, GPR:$src2)&gt;;
641
642<b>class</b> riinst&lt;<b>int</b> opc, <b>string</b> asmstr&gt;
643 : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
644 (ops GPR:$dst, GPR:$src1, Imm:$src2)&gt;;
645
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]646<i>// Instantiations of the ri_inst multiclass.</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]647<b>def</b> ADD_rr : rrinst&lt;0b111, "add"&gt;;
648<b>def</b> ADD_ri : riinst&lt;0b111, "add"&gt;;
649<b>def</b> SUB_rr : rrinst&lt;0b101, "sub"&gt;;
650<b>def</b> SUB_ri : riinst&lt;0b101, "sub"&gt;;
651<b>def</b> MUL_rr : rrinst&lt;0b100, "mul"&gt;;
652<b>def</b> MUL_ri : riinst&lt;0b100, "mul"&gt;;
653...
654</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]655</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]656
657</div>
658
659<!-- ======================================================================= -->
660<div class="doc_subsection">
661 <a name="filescope">File scope entities</a>
662</div>
663
664<!-- -------------------------------------------------------------------------->
665<div class="doc_subsubsection">
666 <a name="include">File inclusion</a>
667</div>
668
669<div class="doc_text">
670<p>TableGen supports the '<tt>include</tt>' token, which textually substitutes
671the specified file in place of the include directive. The filename should be
672specified as a double quoted string immediately after the '<tt>include</tt>'
673keyword. Example:</p>
674
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]675<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]676<pre>
677<b>include</b> "foo.td"
678</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]679</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]680
681</div>
682
683<!-- -------------------------------------------------------------------------->
684<div class="doc_subsubsection">
685 <a name="globallet">'let' expressions</a>
686</div>
687
688<div class="doc_text">
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]689
690<p>"Let" expressions at file scope are similar to <a href="#recordlet">"let"
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]691expressions within a record</a>, except they can specify a value binding for
692multiple records at a time, and may be useful in certain other cases.
693File-scope let expressions are really just another way that TableGen allows the
694end-user to factor out commonality from the records.</p>
695
696<p>File-scope "let" expressions take a comma-separated list of bindings to
Matthijs Kooijman16bb03a2008-10-20 08:45:34 +0000[diff] [blame]697apply, and one or more records to bind the values in. Here are some
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]698examples:</p>
699
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]700<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]701<pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]702<b>let</b> isTerminator = 1, isReturn = 1, isBarrier = 1, hasCtrlDep = 1 <b>in</b>
703 <b>def</b> RET : I&lt;0xC3, RawFrm, (outs), (ins), "ret", [(X86retflag 0)]&gt;;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]704
705<b>let</b> isCall = 1 <b>in</b>
706 <i>// All calls clobber the non-callee saved registers...</i>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]707 <b>let</b> Defs = [EAX, ECX, EDX, FP0, FP1, FP2, FP3, FP4, FP5, FP6, ST0,
708 MM0, MM1, MM2, MM3, MM4, MM5, MM6, MM7,
709 XMM0, XMM1, XMM2, XMM3, XMM4, XMM5, XMM6, XMM7, EFLAGS] <b>in</b> {
Dan Gohman8e58bc52008-10-14 17:00:38 +0000[diff] [blame]710 <b>def</b> CALLpcrel32 : Ii32&lt;0xE8, RawFrm, (outs), (ins i32imm:$dst,variable_ops),
711 "call\t${dst:call}", []&gt;;
712 <b>def</b> CALL32r : I&lt;0xFF, MRM2r, (outs), (ins GR32:$dst, variable_ops),
713 "call\t{*}$dst", [(X86call GR32:$dst)]&gt;;
714 <b>def</b> CALL32m : I&lt;0xFF, MRM2m, (outs), (ins i32mem:$dst, variable_ops),
715 "call\t{*}$dst", []&gt;;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]716 }
717</pre>
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]718</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]719
720<p>File-scope "let" expressions are often useful when a couple of definitions
721need to be added to several records, and the records do not otherwise need to be
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]722opened, as in the case with the <tt>CALL*</tt> instructions above.</p>
723
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]724</div>
725
726<!-- *********************************************************************** -->
727<div class="doc_section"><a name="backends">TableGen backends</a></div>
728<!-- *********************************************************************** -->
729
730<div class="doc_text">
Bill Wendling707b6ab2008-02-12 07:06:19 +0000[diff] [blame]731
732<p>TODO: How they work, how to write one. This section should not contain
733details about any particular backend, except maybe -print-enums as an example.
734This should highlight the APIs in <tt>TableGen/Record.h</tt>.</p>
735
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]736</div>
737
738<!-- *********************************************************************** -->
739
740<hr>
741<address>
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Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]746
747 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
748 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
749 Last modified: $Date$
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751
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