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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;
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]141 <b>bit</b> isSimpleLoad = 0;
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
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]304<ul>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]305<dl>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]306
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]307<dt><tt><b>bit</b></tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]308 <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]309
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]310<dt><tt><b>int</b></tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]311 <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]312
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]313<dt><tt><b>string</b></tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]314 <dd>The 'string' type represents an ordered sequence of characters of
315 arbitrary length.</dd>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]316
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]317<dt><tt><b>bits</b>&lt;n&gt;</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]318 <dd>A 'bits' type is an arbitrary, but fixed, size integer that is broken up
319 into individual bits. This type is useful because it can handle some bits
320 being defined while others are undefined.</dd>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]321
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]322<dt><tt><b>list</b>&lt;ty&gt;</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]323 <dd>This type represents a list whose elements are some other type. The
324 contained type is arbitrary: it can even be another list type.</dd>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]325
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]326<dt>Class type</dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]327 <dd>Specifying a class name in a type context means that the defined value
328 must be a subclass of the specified class. This is useful in conjunction with
329 the <b><tt>list</tt></b> type, for example, to constrain the elements of the
330 list to a common base class (e.g., a <tt><b>list</b>&lt;Register&gt;</tt> can
331 only contain definitions derived from the "<tt>Register</tt>" class).</dd>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]332
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]333<dt><tt><b>dag</b></tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]334 <dd>This type represents a nestable directed graph of elements.</dd>
335
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]336<dt><tt><b>code</b></tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]337 <dd>This represents a big hunk of text. NOTE: I don't remember why this is
338 distinct from string!</dd>
339</dl>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]340</ul>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]341
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]342<p>To date, these types have been sufficient for describing things that
343TableGen has been used for, but it is straight-forward to extend this list if
344needed.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]345
346</div>
347
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]348<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]349<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]350 <a name="values">TableGen values and expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]351</div>
352
Misha Brukman78b648c2004-06-03 16:59:59 +0000[diff] [blame]353<div class="doc_text">
354
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]355<p>TableGen allows for a pretty reasonable number of different expression forms
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]356when building up values. These forms allow the TableGen file to be written in a
357natural syntax and flavor for the application. The current expression forms
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]358supported include:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]359
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]360<ul>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]361<dl>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]362<dt><tt>?</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]363 <dd>uninitialized field</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]364<dt><tt>0b1001011</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]365 <dd>binary integer value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]366<dt><tt>07654321</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]367 <dd>octal integer value (indicated by a leading 0)</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]368<dt><tt>7</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]369 <dd>decimal integer value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]370<dt><tt>0x7F</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]371 <dd>hexadecimal integer value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]372<dt><tt>"foo"</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]373 <dd>string value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]374<dt><tt>[{ ... }]</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]375 <dd>code fragment</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]376<dt><tt>[ X, Y, Z ]</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]377 <dd>list value.</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]378<dt><tt>{ a, b, c }</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]379 <dd>initializer for a "bits&lt;3&gt;" value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]380<dt><tt>value</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]381 <dd>value reference</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]382<dt><tt>value{17}</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]383 <dd>access to one bit of a value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]384<dt><tt>value{15-17}</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]385 <dd>access to multiple bits of a value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]386<dt><tt>DEF</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]387 <dd>reference to a record definition</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]388<dt><tt>CLASS&lt;val list&gt;</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]389 <dd>reference to a new anonymous definition of CLASS with the specified
390 template arguments.</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]391<dt><tt>X.Y</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]392 <dd>reference to the subfield of a value</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]393<dt><tt>list[4-7,17,2-3]</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]394 <dd>A slice of the 'list' list, including elements 4,5,6,7,17,2, and 3 from
395 it. Elements may be included multiple times.</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]396<dt><tt>(DEF a, b)</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]397 <dd>a dag value. The first element is required to be a record definition, the
398 remaining elements in the list may be arbitrary other values, including nested
399 `<tt>dag</tt>' values.</dd>
Bill Wendling58d96d62008-02-12 07:09:05 +0000[diff] [blame^]400<dt><tt>!strconcat(a, b)</tt></dt>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]401 <dd>A string value that is the result of concatenating the 'a' and 'b'
402 strings.</dd>
403</dl>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]404</ul>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]405
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]406<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]407for different types. These rules allow you to assign a value like "<tt>7</tt>"
408to a "<tt>bits&lt;4&gt;</tt>" value, for example.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]409
410</div>
411
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]412<!-- ======================================================================= -->
Misha Brukman78b648c2004-06-03 16:59:59 +0000[diff] [blame]413<div class="doc_subsection">
414 <a name="classesdefs">Classes and definitions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]415</div>
416
Misha Brukman78b648c2004-06-03 16:59:59 +0000[diff] [blame]417<div class="doc_text">
418
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]419<p>As mentioned in the <a href="#concepts">intro</a>, classes and definitions
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]420(collectively known as 'records') in TableGen are the main high-level unit of
421information that TableGen collects. Records are defined with a <tt>def</tt> or
422<tt>class</tt> keyword, the record name, and an optional list of "<a
Misha Brukman179bf4b2004-06-03 23:42:24 +0000[diff] [blame]423href="#templateargs">template arguments</a>". If the record has superclasses,
Jeff Cohen0b81cda2005-10-24 16:54:55 +0000[diff] [blame]424they are specified as a comma separated list that starts with a colon character
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]425("<tt>:</tt>"). If <a href="#valuedef">value definitions</a> or <a
426href="#recordlet">let expressions</a> are needed for the class, they are
427enclosed in curly braces ("<tt>{}</tt>"); otherwise, the record ends with a
428semicolon.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]429
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]430<p>Here is a simple TableGen file:</p>
431
432<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]433<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]434<b>class</b> C { <b>bit</b> V = 1; }
435<b>def</b> X : C;
436<b>def</b> Y : C {
437 <b>string</b> Greeting = "hello";
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]438}
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]439</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]440</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]441
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]442<p>This example defines two definitions, <tt>X</tt> and <tt>Y</tt>, both of
443which derive from the <tt>C</tt> class. Because of this, they both get the
444<tt>V</tt> bit value. The <tt>Y</tt> definition also gets the Greeting member
445as well.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]446
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]447<p>In general, classes are useful for collecting together the commonality
448between a group of records and isolating it in a single place. Also, classes
449permit the specification of default values for their subclasses, allowing the
450subclasses to override them as they wish.</p>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]451
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]452</div>
453
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]454<!---------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]455<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]456 <a name="valuedef">Value definitions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]457</div>
458
459<div class="doc_text">
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]460
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]461<p>Value definitions define named entries in records. A value must be defined
John Criswellaa55c8c2004-02-12 18:11:53 +0000[diff] [blame]462before it can be referred to as the operand for another value definition or
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]463before the value is reset with a <a href="#recordlet">let expression</a>. A
464value is defined by specifying a <a href="#types">TableGen type</a> and a name.
465If an initial value is available, it may be specified after the type with an
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]466equal sign. Value definitions require terminating semicolons.</p>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]467
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]468</div>
469
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]470<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]471<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]472 <a name="recordlet">'let' expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]473</div>
474
475<div class="doc_text">
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]476
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]477<p>A record-level let expression is used to change the value of a value
478definition in a record. This is primarily useful when a superclass defines a
479value that a derived class or definition wants to override. Let expressions
480consist of the '<tt>let</tt>' keyword followed by a value name, an equal sign
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]481("<tt>=</tt>"), and a new value. For example, a new class could be added to the
482example above, redefining the <tt>V</tt> field for all of its subclasses:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]483
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]484<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]485<pre>
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]486<b>class</b> D : C { let V = 0; }
487<b>def</b> Z : D;
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]488</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]489</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]490
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]491<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]492value, despite the fact that it derives (indirectly) from the <tt>C</tt> class,
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]493because the <tt>D</tt> class overrode its value.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]494
495</div>
496
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]497<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]498<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]499 <a name="templateargs">Class template arguments</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]500</div>
501
502<div class="doc_text">
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]503
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]504<p>TableGen permits the definition of parameterized classes as well as normal
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]505concrete classes. Parameterized TableGen classes specify a list of variable
506bindings (which may optionally have defaults) that are bound when used. Here is
507a simple example:</p>
508
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]509<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]510<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]511<b>class</b> FPFormat&lt;<b>bits</b>&lt;3&gt; val&gt; {
512 <b>bits</b>&lt;3&gt; Value = val;
513}
514<b>def</b> NotFP : FPFormat&lt;0&gt;;
515<b>def</b> ZeroArgFP : FPFormat&lt;1&gt;;
516<b>def</b> OneArgFP : FPFormat&lt;2&gt;;
517<b>def</b> OneArgFPRW : FPFormat&lt;3&gt;;
518<b>def</b> TwoArgFP : FPFormat&lt;4&gt;;
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]519<b>def</b> CompareFP : FPFormat&lt;5&gt;;
520<b>def</b> CondMovFP : FPFormat&lt;6&gt;;
521<b>def</b> SpecialFP : FPFormat&lt;7&gt;;
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]522</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]523</div>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]524
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]525<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]526a list of "enumeration values", each with a "<tt>Value</tt>" field set to the
527specified integer.</p>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]528
529<p>The more esoteric forms of <a href="#values">TableGen expressions</a> are
530useful in conjunction with template arguments. As an example:</p>
531
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]532<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]533<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]534<b>class</b> ModRefVal&lt;<b>bits</b>&lt;2&gt; val&gt; {
535 <b>bits</b>&lt;2&gt; Value = val;
536}
537
538<b>def</b> None : ModRefVal&lt;0&gt;;
539<b>def</b> Mod : ModRefVal&lt;1&gt;;
540<b>def</b> Ref : ModRefVal&lt;2&gt;;
541<b>def</b> ModRef : ModRefVal&lt;3&gt;;
542
543<b>class</b> Value&lt;ModRefVal MR&gt; {
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]544 <i>// Decode some information into a more convenient format, while providing
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]545 // a nice interface to the user of the "Value" class.</i>
546 <b>bit</b> isMod = MR.Value{0};
547 <b>bit</b> isRef = MR.Value{1};
548
549 <i>// other stuff...</i>
550}
551
552<i>// Example uses</i>
553<b>def</b> bork : Value&lt;Mod&gt;;
554<b>def</b> zork : Value&lt;Ref&gt;;
555<b>def</b> hork : Value&lt;ModRef&gt;;
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]556</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]557</div>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]558
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]559<p>This is obviously a contrived example, but it shows how template arguments
560can 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]561actual internal data representation expected by the class. In this case,
562running <tt>tblgen</tt> on the example prints the following definitions:</p>
563
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]564<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]565<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]566<b>def</b> bork { <i>// Value</i>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]567 <b>bit</b> isMod = 1;
568 <b>bit</b> isRef = 0;
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]569}
570<b>def</b> hork { <i>// Value</i>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]571 <b>bit</b> isMod = 1;
572 <b>bit</b> isRef = 1;
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]573}
574<b>def</b> zork { <i>// Value</i>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]575 <b>bit</b> isMod = 0;
576 <b>bit</b> isRef = 1;
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]577}
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]578</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]579</div>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]580
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]581<p> This shows that TableGen was able to dig into the argument and extract a
582piece of information that was requested by the designer of the "Value" class.
583For more realistic examples, please see existing users of TableGen, such as the
584X86 backend.</p>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]585
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]586</div>
587
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]588<!-- -------------------------------------------------------------------------->
589<div class="doc_subsubsection">
590 <a name="multiclass">Multiclass definitions and instances</a>
591</div>
592
593<div class="doc_text">
594
595<p>
596While classes with template arguments are a good way to factor commonality
597between two instances of a definition, multiclasses allow a convenient notation
598for defining multiple definitions at once (instances of implicitly constructed
599classes). For example, consider an 3-address instruction set whose instructions
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]600come in two forms: "<tt>reg = reg op reg</tt>" and "<tt>reg = reg op imm</tt>"
601(e.g. SPARC). In this case, you'd like to specify in one place that this
602commonality exists, then in a separate place indicate what all the ops are.
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]603</p>
604
605<p>
606Here is an example TableGen fragment that shows this idea:
607</p>
608
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]609<div class="doc_code">
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]610<pre>
611<b>def</b> ops;
612<b>def</b> GPR;
613<b>def</b> Imm;
614<b>class</b> inst&lt;<b>int</b> opc, <b>string</b> asmstr, <b>dag</b> operandlist&gt;;
615
616<b>multiclass</b> ri_inst&lt;<b>int</b> opc, <b>string</b> asmstr&gt; {
617 def _rr : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
618 (ops GPR:$dst, GPR:$src1, GPR:$src2)&gt;;
619 def _ri : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
620 (ops GPR:$dst, GPR:$src1, Imm:$src2)&gt;;
621}
622
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]623<i>// Instantiations of the ri_inst multiclass.</i>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]624<b>defm</b> ADD : ri_inst&lt;0b111, "add"&gt;;
625<b>defm</b> SUB : ri_inst&lt;0b101, "sub"&gt;;
626<b>defm</b> MUL : ri_inst&lt;0b100, "mul"&gt;;
627...
628</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]629</div>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]630
Chris Lattnere7173e12006-09-01 22:01:36 +0000[diff] [blame]631<p>The name of the resultant definitions has the multidef fragment names
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]632 appended to them, so this defines <tt>ADD_rr</tt>, <tt>ADD_ri</tt>,
633 <tt>SUB_rr</tt>, etc. Using a multiclass this way is exactly equivalent to
634 instantiating the classes multiple times yourself, e.g. by writing:</p>
635
636<div class="doc_code">
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]637<pre>
638<b>def</b> ops;
639<b>def</b> GPR;
640<b>def</b> Imm;
641<b>class</b> inst&lt;<b>int</b> opc, <b>string</b> asmstr, <b>dag</b> operandlist&gt;;
642
643<b>class</b> rrinst&lt;<b>int</b> opc, <b>string</b> asmstr&gt;
644 : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
645 (ops GPR:$dst, GPR:$src1, GPR:$src2)&gt;;
646
647<b>class</b> riinst&lt;<b>int</b> opc, <b>string</b> asmstr&gt;
648 : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
649 (ops GPR:$dst, GPR:$src1, Imm:$src2)&gt;;
650
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]651<i>// Instantiations of the ri_inst multiclass.</i>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]652<b>def</b> ADD_rr : rrinst&lt;0b111, "add"&gt;;
653<b>def</b> ADD_ri : riinst&lt;0b111, "add"&gt;;
654<b>def</b> SUB_rr : rrinst&lt;0b101, "sub"&gt;;
655<b>def</b> SUB_ri : riinst&lt;0b101, "sub"&gt;;
656<b>def</b> MUL_rr : rrinst&lt;0b100, "mul"&gt;;
657<b>def</b> MUL_ri : riinst&lt;0b100, "mul"&gt;;
658...
659</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]660</div>
Chris Lattner84b35982006-09-01 21:44:18 +0000[diff] [blame]661
662</div>
663
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]664<!-- ======================================================================= -->
665<div class="doc_subsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]666 <a name="filescope">File scope entities</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]667</div>
668
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]669<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]670<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]671 <a name="include">File inclusion</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]672</div>
673
674<div class="doc_text">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]675<p>TableGen supports the '<tt>include</tt>' token, which textually substitutes
676the specified file in place of the include directive. The filename should be
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]677specified as a double quoted string immediately after the '<tt>include</tt>'
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]678keyword. Example:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]679
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]680<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]681<pre>
Chris Lattner23f54fa2004-02-06 06:37:00 +0000[diff] [blame]682<b>include</b> "foo.td"
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]683</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]684</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]685
686</div>
687
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]688<!-- -------------------------------------------------------------------------->
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]689<div class="doc_subsubsection">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]690 <a name="globallet">'let' expressions</a>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]691</div>
692
693<div class="doc_text">
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]694
695<p>"Let" expressions at file scope are similar to <a href="#recordlet">"let"
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]696expressions within a record</a>, except they can specify a value binding for
697multiple records at a time, and may be useful in certain other cases.
698File-scope let expressions are really just another way that TableGen allows the
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]699end-user to factor out commonality from the records.</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]700
Jeff Cohen0b81cda2005-10-24 16:54:55 +0000[diff] [blame]701<p>File-scope "let" expressions take a comma-separated list of bindings to
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]702apply, and one of more records to bind the values in. Here are some
703examples:</p>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]704
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]705<div class="doc_code">
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]706<pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]707<b>let</b> isTerminator = 1, isReturn = 1, isBarrier = 1, hasCtrlDep = 1 <b>in</b>
708 <b>def</b> RET : I&lt;0xC3, RawFrm, (outs), (ins), "ret", [(X86retflag 0)]&gt;;
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]709
Chris Lattnerfa6f3092004-02-06 06:04:25 +0000[diff] [blame]710<b>let</b> isCall = 1 <b>in</b>
711 <i>// All calls clobber the non-callee saved registers...</i>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]712 <b>let</b> Defs = [EAX, ECX, EDX, FP0, FP1, FP2, FP3, FP4, FP5, FP6, ST0,
713 MM0, MM1, MM2, MM3, MM4, MM5, MM6, MM7,
714 XMM0, XMM1, XMM2, XMM3, XMM4, XMM5, XMM6, XMM7, EFLAGS] <b>in</b> {
715 <b>def</b> CALLpcrel32 : Ii32<0xE8, RawFrm, (outs), (ins i32imm:$dst,variable_ops),
716 "call\t${dst:call}", []>;
717 <b>def</b> CALL32r : I<0xFF, MRM2r, (outs), (ins GR32:$dst, variable_ops),
718 "call\t{*}$dst", [(X86call GR32:$dst)]>;
719 <b>def</b> CALL32m : I<0xFF, MRM2m, (outs), (ins i32mem:$dst, variable_ops),
720 "call\t{*}$dst", []>;
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]721 }
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]722</pre>
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]723</div>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]724
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]725<p>File-scope "let" expressions are often useful when a couple of definitions
726need 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]727opened, as in the case with the <tt>CALL*</tt> instructions above.</p>
728
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]729</div>
730
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]731<!-- *********************************************************************** -->
732<div class="doc_section"><a name="backends">TableGen backends</a></div>
733<!-- *********************************************************************** -->
734
735<div class="doc_text">
Bill Wendling643eb5d2008-02-12 07:06:19 +0000[diff] [blame]736
737<p>TODO: How they work, how to write one. This section should not contain
738details about any particular backend, except maybe -print-enums as an example.
739This should highlight the APIs in <tt>TableGen/Record.h</tt>.</p>
740
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]741</div>
742
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]743<!-- *********************************************************************** -->
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]744
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]745<hr>
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]746<address>
747 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]751
752 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]753 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Chris Lattnerb54c99c2004-02-06 05:42:53 +0000[diff] [blame]754 Last modified: $Date$
Misha Brukman85234ac2004-05-12 18:31:21 +0000[diff] [blame]755</address>
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758</html>