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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
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>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]33 <li><a href="#multiclass">Multiclass definitions and instances</a></li>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]34 </ol></li>
35 <li><a href="#filescope">File scope entities</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]36 <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 +0000[diff] [blame]39 </ol></li>
40 </ol></li>
41 <li><a href="#backends">TableGen backends</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]42 <ol>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]43 <li><a href="#">todo</a></li>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]44 </ol></li>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]45</ul>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]46</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]47
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]48<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 +0000[diff] [blame]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
Chris Lattner1aab3272004-07-26 21:16:55 +0000[diff] [blame]68of TableGen is the <a href="CodeGenerator.html">LLVM code generator</a>.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]69
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]70<p>Note that if you work on TableGen much, and use emacs or vim, that you can
Bill Wendling643eb5d2008-02-12 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
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]73distribution, respectively.</p>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]74
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]75</div>
76
77<!-- ======================================================================= -->
Jim Laskeyf1b5adb2006-09-09 09:10:37 +0000[diff] [blame]78<div class="doc_subsection"><a name="concepts">Basic concepts</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]79
80<div class="doc_text">
81
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]82<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 +0000[diff] [blame]84
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]85<p><b>TableGen records</b> have a unique name, a list of values, and a list of
Bill Wendling643eb5d2008-02-12 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
Chris Lattnerb54c99c2004-02-06 05:42:53 +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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]90taken care of and are fixed by TableGen.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]91
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]95
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]98abstractions for either the domain they are targeting (such as "Register",
Misha Brukman85234ac2004-05-12 18:31:21 +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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]105
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]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
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]110</div>
111
112<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]113<div class="doc_subsection"><a name="example">An example record</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]114
115<div class="doc_text">
116
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]121
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]122<div class="doc_code">
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]123<pre>
124...
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]125<b>def</b> ADD32rr { <i>// Instruction X86Inst I</i>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]126 <b>string</b> Namespace = "X86";
Bill Wendling643eb5d2008-02-12 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))];
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]131 <b>list</b>&lt;Register&gt; Uses = [];
Bill Wendling643eb5d2008-02-12 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;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]136 <b>bit</b> isReturn = 0;
137 <b>bit</b> isBranch = 0;
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]138 <b>bit</b> isIndirectBranch = 0;
139 <b>bit</b> isBarrier = 0;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]140 <b>bit</b> isCall = 0;
Dan Gohman15511cf2008-12-03 18:15:48 +0000[diff] [blame^]141 <b>bit</b> canFoldAsLoad = 0;
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]142 <b>bit</b> mayLoad = 0;
143 <b>bit</b> mayStore = 0;
144 <b>bit</b> isImplicitDef = 0;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]145 <b>bit</b> isTwoAddress = 1;
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]146 <b>bit</b> isConvertibleToThreeAddress = 1;
147 <b>bit</b> isCommutable = 1;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]148 <b>bit</b> isTerminator = 0;
Bill Wendling643eb5d2008-02-12 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 };
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]162 Format Form = MRMDestReg;
Bill Wendling643eb5d2008-02-12 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 };
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]166 <b>bit</b> hasOpSizePrefix = 0;
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]167 <b>bit</b> hasAdSizePrefix = 0;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]168 <b>bits</b>&lt;4&gt; Prefix = { 0, 0, 0, 0 };
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]169 <b>bit</b> hasREX_WPrefix = 0;
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]170 FPFormat FPForm = ?;
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]171 <b>bits</b>&lt;3&gt; FPFormBits = { 0, 0, 0 };
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]172}
173...
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]174</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]175</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]176
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]177<p>This definition corresponds to a 32-bit register-register add instruction in
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]178the X86. The string after the '<tt>def</tt>' string indicates the name of the
Bill Wendling643eb5d2008-02-12 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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]187
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]193
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]194<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]195<pre>
Bill Wendling643eb5d2008-02-12 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;;
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]203</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]204</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]205
Bill Wendling643eb5d2008-02-12 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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]211
212</div>
213
214<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]215<div class="doc_subsection"><a name="running">Running TableGen</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]216
217<div class="doc_text">
218
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]219<p>TableGen runs just like any other LLVM tool. The first (optional) argument
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]220specifies the file to read. If a filename is not specified, <tt>tblgen</tt>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]221reads from standard input.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]222
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]225-help</tt>' for a list). For example, to get a list of all of the definitions
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]226that subclass a particular type (which can be useful for building up an enum
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]227list of these records), use the <tt>-print-enums</tt> option:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]228
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]229<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]230<pre>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]231$ tblgen X86.td -print-enums -class=Register
Bill Wendling643eb5d2008-02-12 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,
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]240
241$ tblgen X86.td -print-enums -class=Instruction
Bill Wendling643eb5d2008-02-12 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, ...
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]247</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]248</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]249
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]250<p>The default backend prints out all of the records, as described <a
251href="#example">above</a>.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]252
Bill Wendling643eb5d2008-02-12 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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +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 Wendling643eb5d2008-02-12 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.
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]268This section describes the syntax and the constructs allowed in a TableGen file.
269</p>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]270
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]271</div>
272
273<!-- ======================================================================= -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]274<div class="doc_subsection"><a name="primitives">TableGen primitives</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]275
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]276<!-- -------------------------------------------------------------------------->
277<div class="doc_subsubsection"><a name="comments">TableGen comments</a></div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]278
279<div class="doc_text">
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]280
Chris Lattnerb54c99c2004-02-06 05:42:53 +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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]283
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]284</div>
285
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]286<!-- -------------------------------------------------------------------------->
Misha Brukman78b648c2004-06-03 16:59:59 +0000[diff] [blame]287<div class="doc_subsubsection">
288 <a name="types">The TableGen type system</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]289</div>
290
291<div class="doc_text">
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]292
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]293<p>TableGen files are strongly typed, in a simple (but complete) type-system.
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]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
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]303
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]304<dl>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]305<dt><tt><b>bit</b></tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]306 <dd>A 'bit' is a boolean value that can hold either 0 or 1.</dd>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]307
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]308<dt><tt><b>int</b></tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]309 <dd>The 'int' type represents a simple 32-bit integer value, such as 5.</dd>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]310
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]311<dt><tt><b>string</b></tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]312 <dd>The 'string' type represents an ordered sequence of characters of
313 arbitrary length.</dd>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]314
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]315<dt><tt><b>bits</b>&lt;n&gt;</tt></dt>
Bill Wendling643eb5d2008-02-12 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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]319
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]320<dt><tt><b>list</b>&lt;ty&gt;</tt></dt>
Bill Wendling643eb5d2008-02-12 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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]323
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]324<dt>Class type</dt>
Bill Wendling643eb5d2008-02-12 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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]330
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]331<dt><tt><b>dag</b></tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]332 <dd>This type represents a nestable directed graph of elements.</dd>
333
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]334<dt><tt><b>code</b></tt></dt>
Bill Wendling643eb5d2008-02-12 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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]338
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]342
343</div>
344
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]345<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]346<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]347 <a name="values">TableGen values and expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]348</div>
349
Misha Brukman78b648c2004-06-03 16:59:59 +0000[diff] [blame]350<div class="doc_text">
351
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]352<p>TableGen allows for a pretty reasonable number of different expression forms
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]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
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]355supported include:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]356
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]357<dl>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]358<dt><tt>?</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]359 <dd>uninitialized field</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]360<dt><tt>0b1001011</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]361 <dd>binary integer value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]362<dt><tt>07654321</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]363 <dd>octal integer value (indicated by a leading 0)</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]364<dt><tt>7</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]365 <dd>decimal integer value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]366<dt><tt>0x7F</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]367 <dd>hexadecimal integer value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]368<dt><tt>"foo"</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]369 <dd>string value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]370<dt><tt>[{ ... }]</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]371 <dd>code fragment</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]372<dt><tt>[ X, Y, Z ]</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]373 <dd>list value.</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]374<dt><tt>{ a, b, c }</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]375 <dd>initializer for a "bits&lt;3&gt;" value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]376<dt><tt>value</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]377 <dd>value reference</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]378<dt><tt>value{17}</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]379 <dd>access to one bit of a value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]380<dt><tt>value{15-17}</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]381 <dd>access to multiple bits of a value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]382<dt><tt>DEF</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]383 <dd>reference to a record definition</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]384<dt><tt>CLASS&lt;val list&gt;</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]385 <dd>reference to a new anonymous definition of CLASS with the specified
386 template arguments.</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]387<dt><tt>X.Y</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]388 <dd>reference to the subfield of a value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]389<dt><tt>list[4-7,17,2-3]</tt></dt>
Bill Wendling643eb5d2008-02-12 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 Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]392<dt><tt>(DEF a, b)</tt></dt>
Bill Wendling643eb5d2008-02-12 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 Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]396<dt><tt>!strconcat(a, b)</tt></dt>
Bill Wendling643eb5d2008-02-12 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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]400
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]401<p>Note that all of the values have rules specifying how they convert to values
Bill Wendling643eb5d2008-02-12 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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]404
405</div>
406
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]407<!-- ======================================================================= -->
Misha Brukman78b648c2004-06-03 16:59:59 +0000[diff] [blame]408<div class="doc_subsection">
409 <a name="classesdefs">Classes and definitions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]410</div>
411
Misha Brukman78b648c2004-06-03 16:59:59 +0000[diff] [blame]412<div class="doc_text">
413
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]414<p>As mentioned in the <a href="#concepts">intro</a>, classes and definitions
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]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
Misha Brukman179bf4b2004-06-03 23:42:24 +0000[diff] [blame]418href="#templateargs">template arguments</a>". If the record has superclasses,
Jeff Cohen0b81cda2005-10-24 16:54:55 +0000[diff] [blame]419they are specified as a comma separated list that starts with a colon character
Bill Wendling643eb5d2008-02-12 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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]424
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]425<p>Here is a simple TableGen file:</p>
426
427<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]428<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]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";
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]433}
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]434</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]435</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]436
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]441
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]446
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]447</div>
448
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]449<!---------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]450<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]451 <a name="valuedef">Value definitions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]452</div>
453
454<div class="doc_text">
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]455
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]456<p>Value definitions define named entries in records. A value must be defined
John Criswellaa55c8c2004-02-12 18:11:53 +0000[diff] [blame]457before it can be referred to as the operand for another value definition or
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]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
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]461equal sign. Value definitions require terminating semicolons.</p>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]462
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]463</div>
464
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]465<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]466<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]467 <a name="recordlet">'let' expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]468</div>
469
470<div class="doc_text">
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]471
Misha Brukman85234ac2004-05-12 18:31:21 +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 Wendling643eb5d2008-02-12 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>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]478
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]479<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]480<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]481<b>class</b> D : C { let V = 0; }
482<b>def</b> Z : D;
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]483</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]484</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]485
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]486<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]487value, despite the fact that it derives (indirectly) from the <tt>C</tt> class,
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]488because the <tt>D</tt> class overrode its value.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]489
490</div>
491
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]492<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]493<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]494 <a name="templateargs">Class template arguments</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]495</div>
496
497<div class="doc_text">
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]498
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]499<p>TableGen permits the definition of parameterized classes as well as normal
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]504<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]505<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]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 Wendling643eb5d2008-02-12 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;;
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]517</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]518</div>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]519
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]520<p>In this case, template arguments are used as a space efficient way to specify
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]521a list of "enumeration values", each with a "<tt>Value</tt>" field set to the
522specified integer.</p>
Chris Lattner23f54fa2004-02-06 06:37:00 +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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]527<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]528<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]539 <i>// Decode some information into a more convenient format, while providing
Chris Lattner23f54fa2004-02-06 06:37:00 +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;;
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]551</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]552</div>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]553
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]559<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]560<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]561<b>def</b> bork { <i>// Value</i>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]562 <b>bit</b> isMod = 1;
563 <b>bit</b> isRef = 0;
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]564}
565<b>def</b> hork { <i>// Value</i>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]566 <b>bit</b> isMod = 1;
567 <b>bit</b> isRef = 1;
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]568}
569<b>def</b> zork { <i>// Value</i>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]570 <b>bit</b> isMod = 0;
571 <b>bit</b> isRef = 1;
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]572}
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]573</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]574</div>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]575
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]580
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]581</div>
582
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]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 Wendling643eb5d2008-02-12 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.
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]598</p>
599
600<p>
601Here is an example TableGen fragment that shows this idea:
602</p>
603
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]604<div class="doc_code">
Chris Lattner84b35982006-09-01 21:44:18 +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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]618<i>// Instantiations of the ri_inst multiclass.</i>
Chris Lattner84b35982006-09-01 21:44:18 +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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]624</div>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]625
Chris Lattnere7173e12006-09-01 22:01:36 +0000[diff] [blame]626<p>The name of the resultant definitions has the multidef fragment names
Bill Wendling643eb5d2008-02-12 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">
Chris Lattner84b35982006-09-01 21:44:18 +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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]646<i>// Instantiations of the ri_inst multiclass.</i>
Chris Lattner84b35982006-09-01 21:44:18 +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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]655</div>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]656
657</div>
658
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]659<!-- ======================================================================= -->
660<div class="doc_subsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]661 <a name="filescope">File scope entities</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]662</div>
663
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]664<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]665<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]666 <a name="include">File inclusion</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]667</div>
668
669<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]672specified as a double quoted string immediately after the '<tt>include</tt>'
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]673keyword. Example:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]674
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]675<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]676<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]677<b>include</b> "foo.td"
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]678</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]679</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]680
681</div>
682
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]683<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]684<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]685 <a name="globallet">'let' expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]686</div>
687
688<div class="doc_text">
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]689
690<p>"Let" expressions at file scope are similar to <a href="#recordlet">"let"
Chris Lattnerb54c99c2004-02-06 05:42:53 +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
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]694end-user to factor out commonality from the records.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]695
Jeff Cohen0b81cda2005-10-24 16:54:55 +0000[diff] [blame]696<p>File-scope "let" expressions take a comma-separated list of bindings to
Matthijs Kooijman94199da2008-10-20 08:45:34 +0000[diff] [blame]697apply, and one or more records to bind the values in. Here are some
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]698examples:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]699
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]700<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]701<pre>
Bill Wendling643eb5d2008-02-12 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;;
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]704
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]705<b>let</b> isCall = 1 <b>in</b>
706 <i>// All calls clobber the non-callee saved registers...</i>
Bill Wendling643eb5d2008-02-12 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 Gohman364a39f2008-10-14 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;;
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]716 }
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]717</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]718</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]719
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]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 Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]722opened, as in the case with the <tt>CALL*</tt> instructions above.</p>
723
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]724</div>
725
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]726<!-- *********************************************************************** -->
727<div class="doc_section"><a name="backends">TableGen backends</a></div>
728<!-- *********************************************************************** -->
729
730<div class="doc_text">
Bill Wendling643eb5d2008-02-12 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
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]736</div>
737
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]738<!-- *********************************************************************** -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]739
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]740<hr>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]741<address>
742 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
743 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
744 <a href="http://validator.w3.org/check/referer"><img
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame]745 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]746
747 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]748 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]749 Last modified: $Date$
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]750</address>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]751
752</body>
753</html>