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5 <title>TableGen Fundamentals</title>
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7</head>
8<body>
9
10<div class="doc_title">TableGen Fundamentals</div>
11
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]12<div class="doc_text">
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]13<ul>
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]14 <li><a href="#introduction">Introduction</a>
Chris Lattner149a2492004-02-06 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 Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]19 </ol></li>
20 <li><a href="#syntax">TableGen syntax</a>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]21 <ol>
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]22 <li><a href="#primitives">TableGen primitives</a>
Chris Lattner149a2492004-02-06 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 Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]27 </ol></li>
28 <li><a href="#classesdefs">Classes and definitions</a>
Chris Lattner149a2492004-02-06 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 Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]33 <li><a href="#multiclass">Multiclass definitions and instances</a></li>
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]34 </ol></li>
35 <li><a href="#filescope">File scope entities</a>
Chris Lattner149a2492004-02-06 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 Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]39 </ol></li>
40 </ol></li>
41 <li><a href="#backends">TableGen backends</a>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]42 <ol>
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]43 <li><a href="#">todo</a></li>
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]44 </ol></li>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]45</ul>
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]46</div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]47
Chris Lattner020e1fc2004-05-23 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 Lattner149a2492004-02-06 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 Lattner7f500132004-07-26 21:16:55 +0000[diff] [blame]68of TableGen is the <a href="CodeGenerator.html">LLVM code generator</a>.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]69
Misha Brukman692cec02004-05-12 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 Wendling1a19af92008-02-12 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 Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]73distribution, respectively.</p>
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]74
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]75</div>
76
77<!-- ======================================================================= -->
Jim Laskeyea05a062006-09-09 09:10:37 +0000[diff] [blame]78<div class="doc_subsection"><a name="concepts">Basic concepts</a></div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]79
80<div class="doc_text">
81
Misha Brukman692cec02004-05-12 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 Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]84
Misha Brukman692cec02004-05-12 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 Wendling1a19af92008-02-12 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 Lattner149a2492004-02-06 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 Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]90taken care of and are fixed by TableGen.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]91
Misha Brukman692cec02004-05-12 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 Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]95
Misha Brukman692cec02004-05-12 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 Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]98abstractions for either the domain they are targeting (such as "Register",
Misha Brukman692cec02004-05-12 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 Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]105
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]106<p><b>TableGen multiclasses</b> are groups of abstract records that are
David Greene753ed8f2009-04-22 16:42:54 +0000[diff] [blame^]107instantiated all at once. Each instantiation can result in multiple
108TableGen definitions. If a multiclass inherits from another multiclass,
109the definitions in the sub-multiclass become part of the current
110multiclass, as if they were declared in the current multiclass.</p>
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]111
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]112</div>
113
114<!-- ======================================================================= -->
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]115<div class="doc_subsection"><a name="example">An example record</a></div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]116
117<div class="doc_text">
118
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]119<p>With no other arguments, TableGen parses the specified file and prints out
120all of the classes, then all of the definitions. This is a good way to see what
121the various definitions expand to fully. Running this on the <tt>X86.td</tt>
122file prints this (at the time of this writing):</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]123
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]124<div class="doc_code">
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]125<pre>
126...
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]127<b>def</b> ADD32rr { <i>// Instruction X86Inst I</i>
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]128 <b>string</b> Namespace = "X86";
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]129 <b>dag</b> OutOperandList = (outs GR32:$dst);
130 <b>dag</b> InOperandList = (ins GR32:$src1, GR32:$src2);
131 <b>string</b> AsmString = "add{l}\t{$src2, $dst|$dst, $src2}";
132 <b>list</b>&lt;dag&gt; Pattern = [(set GR32:$dst, (add GR32:$src1, GR32:$src2))];
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]133 <b>list</b>&lt;Register&gt; Uses = [];
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]134 <b>list</b>&lt;Register&gt; Defs = [EFLAGS];
135 <b>list</b>&lt;Predicate&gt; Predicates = [];
136 <b>int</b> CodeSize = 3;
137 <b>int</b> AddedComplexity = 0;
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]138 <b>bit</b> isReturn = 0;
139 <b>bit</b> isBranch = 0;
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]140 <b>bit</b> isIndirectBranch = 0;
141 <b>bit</b> isBarrier = 0;
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]142 <b>bit</b> isCall = 0;
Dan Gohman69cc2cb2008-12-03 18:15:48 +0000[diff] [blame]143 <b>bit</b> canFoldAsLoad = 0;
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]144 <b>bit</b> mayLoad = 0;
145 <b>bit</b> mayStore = 0;
146 <b>bit</b> isImplicitDef = 0;
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]147 <b>bit</b> isTwoAddress = 1;
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]148 <b>bit</b> isConvertibleToThreeAddress = 1;
149 <b>bit</b> isCommutable = 1;
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]150 <b>bit</b> isTerminator = 0;
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]151 <b>bit</b> isReMaterializable = 0;
152 <b>bit</b> isPredicable = 0;
153 <b>bit</b> hasDelaySlot = 0;
154 <b>bit</b> usesCustomDAGSchedInserter = 0;
155 <b>bit</b> hasCtrlDep = 0;
156 <b>bit</b> isNotDuplicable = 0;
157 <b>bit</b> hasSideEffects = 0;
158 <b>bit</b> mayHaveSideEffects = 0;
159 <b>bit</b> neverHasSideEffects = 0;
160 InstrItinClass Itinerary = NoItinerary;
161 <b>string</b> Constraints = "";
162 <b>string</b> DisableEncoding = "";
163 <b>bits</b>&lt;8&gt; Opcode = { 0, 0, 0, 0, 0, 0, 0, 1 };
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]164 Format Form = MRMDestReg;
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]165 <b>bits</b>&lt;6&gt; FormBits = { 0, 0, 0, 0, 1, 1 };
166 ImmType ImmT = NoImm;
167 <b>bits</b>&lt;3&gt; ImmTypeBits = { 0, 0, 0 };
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]168 <b>bit</b> hasOpSizePrefix = 0;
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]169 <b>bit</b> hasAdSizePrefix = 0;
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]170 <b>bits</b>&lt;4&gt; Prefix = { 0, 0, 0, 0 };
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]171 <b>bit</b> hasREX_WPrefix = 0;
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]172 FPFormat FPForm = ?;
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]173 <b>bits</b>&lt;3&gt; FPFormBits = { 0, 0, 0 };
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]174}
175...
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]176</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]177</div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]178
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]179<p>This definition corresponds to a 32-bit register-register add instruction in
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]180the X86. The string after the '<tt>def</tt>' string indicates the name of the
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]181record&mdash;"<tt>ADD32rr</tt>" in this case&mdash;and the comment at the end of
182the line indicates the superclasses of the definition. The body of the record
183contains all of the data that TableGen assembled for the record, indicating that
184the instruction is part of the "X86" namespace, the pattern indicating how the
185the instruction should be emitted into the assembly file, that it is a
186two-address instruction, has a particular encoding, etc. The contents and
187semantics of the information in the record is specific to the needs of the X86
188backend, and is only shown as an example.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]189
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]190<p>As you can see, a lot of information is needed for every instruction
191supported by the code generator, and specifying it all manually would be
192unmaintainble, prone to bugs, and tiring to do in the first place. Because we
193are using TableGen, all of the information was derived from the following
194definition:</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]195
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]196<div class="doc_code">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]197<pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]198let Defs = [EFLAGS],
199 isCommutable = 1, <i>// X = ADD Y,Z --&gt; X = ADD Z,Y</i>
200 isConvertibleToThreeAddress = 1 <b>in</b> <i>// Can transform into LEA.</i>
201def ADD32rr : I&lt;0x01, MRMDestReg, (outs GR32:$dst),
202 (ins GR32:$src1, GR32:$src2),
203 "add{l}\t{$src2, $dst|$dst, $src2}",
204 [(set GR32:$dst, (add GR32:$src1, GR32:$src2))]&gt;;
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]205</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]206</div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]207
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]208<p>This definition makes use of the custom class <tt>I</tt> (extended from the
209custom class <tt>X86Inst</tt>), which is defined in the X86-specific TableGen
210file, to factor out the common features that instructions of its class share. A
211key feature of TableGen is that it allows the end-user to define the
212abstractions they prefer to use when describing their information.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]213
214</div>
215
216<!-- ======================================================================= -->
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]217<div class="doc_subsection"><a name="running">Running TableGen</a></div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]218
219<div class="doc_text">
220
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]221<p>TableGen runs just like any other LLVM tool. The first (optional) argument
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]222specifies the file to read. If a filename is not specified, <tt>tblgen</tt>
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]223reads from standard input.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]224
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]225<p>To be useful, one of the <a href="#backends">TableGen backends</a> must be
226used. These backends are selectable on the command line (type '<tt>tblgen
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]227-help</tt>' for a list). For example, to get a list of all of the definitions
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]228that subclass a particular type (which can be useful for building up an enum
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]229list of these records), use the <tt>-print-enums</tt> option:</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]230
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]231<div class="doc_code">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]232<pre>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]233$ tblgen X86.td -print-enums -class=Register
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]234AH, AL, AX, BH, BL, BP, BPL, BX, CH, CL, CX, DH, DI, DIL, DL, DX, EAX, EBP, EBX,
235ECX, EDI, EDX, EFLAGS, EIP, ESI, ESP, FP0, FP1, FP2, FP3, FP4, FP5, FP6, IP,
236MM0, MM1, MM2, MM3, MM4, MM5, MM6, MM7, R10, R10B, R10D, R10W, R11, R11B, R11D,
237R11W, R12, R12B, R12D, R12W, R13, R13B, R13D, R13W, R14, R14B, R14D, R14W, R15,
238R15B, R15D, R15W, R8, R8B, R8D, R8W, R9, R9B, R9D, R9W, RAX, RBP, RBX, RCX, RDI,
239RDX, RIP, RSI, RSP, SI, SIL, SP, SPL, ST0, ST1, ST2, ST3, ST4, ST5, ST6, ST7,
240XMM0, XMM1, XMM10, XMM11, XMM12, XMM13, XMM14, XMM15, XMM2, XMM3, XMM4, XMM5,
241XMM6, XMM7, XMM8, XMM9,
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]242
243$ tblgen X86.td -print-enums -class=Instruction
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]244ABS_F, ABS_Fp32, ABS_Fp64, ABS_Fp80, ADC32mi, ADC32mi8, ADC32mr, ADC32ri,
245ADC32ri8, ADC32rm, ADC32rr, ADC64mi32, ADC64mi8, ADC64mr, ADC64ri32, ADC64ri8,
246ADC64rm, ADC64rr, ADD16mi, ADD16mi8, ADD16mr, ADD16ri, ADD16ri8, ADD16rm,
247ADD16rr, ADD32mi, ADD32mi8, ADD32mr, ADD32ri, ADD32ri8, ADD32rm, ADD32rr,
248ADD64mi32, ADD64mi8, ADD64mr, ADD64ri32, ...
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]249</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]250</div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]251
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]252<p>The default backend prints out all of the records, as described <a
253href="#example">above</a>.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]254
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]255<p>If you plan to use TableGen, you will most likely have to <a
256href="#backends">write a backend</a> that extracts the information specific to
257what you need and formats it in the appropriate way.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]258
259</div>
260
261
262<!-- *********************************************************************** -->
263<div class="doc_section"><a name="syntax">TableGen syntax</a></div>
264<!-- *********************************************************************** -->
265
266<div class="doc_text">
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]267
268<p>TableGen doesn't care about the meaning of data (that is up to the backend to
269define), but it does care about syntax, and it enforces a simple type system.
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]270This section describes the syntax and the constructs allowed in a TableGen file.
271</p>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]272
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]273</div>
274
275<!-- ======================================================================= -->
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]276<div class="doc_subsection"><a name="primitives">TableGen primitives</a></div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]277
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]278<!-- -------------------------------------------------------------------------->
279<div class="doc_subsubsection"><a name="comments">TableGen comments</a></div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]280
281<div class="doc_text">
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]282
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]283<p>TableGen supports BCPL style "<tt>//</tt>" comments, which run to the end of
284the line, and it also supports <b>nestable</b> "<tt>/* */</tt>" comments.</p>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]285
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]286</div>
287
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]288<!-- -------------------------------------------------------------------------->
Misha Brukman94192b62004-06-03 16:59:59 +0000[diff] [blame]289<div class="doc_subsubsection">
290 <a name="types">The TableGen type system</a>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]291</div>
292
293<div class="doc_text">
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]294
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]295<p>TableGen files are strongly typed, in a simple (but complete) type-system.
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]296These types are used to perform automatic conversions, check for errors, and to
297help interface designers constrain the input that they allow. Every <a
298href="#valuedef">value definition</a> is required to have an associated type.
299</p>
300
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]301<p>TableGen supports a mixture of very low-level types (such as <tt>bit</tt>)
302and very high-level types (such as <tt>dag</tt>). This flexibility is what
303allows it to describe a wide range of information conveniently and compactly.
304The TableGen types are:</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]305
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]306<dl>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]307<dt><tt><b>bit</b></tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]308 <dd>A 'bit' is a boolean value that can hold either 0 or 1.</dd>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]309
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]310<dt><tt><b>int</b></tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]311 <dd>The 'int' type represents a simple 32-bit integer value, such as 5.</dd>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]312
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]313<dt><tt><b>string</b></tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]314 <dd>The 'string' type represents an ordered sequence of characters of
315 arbitrary length.</dd>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]316
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]317<dt><tt><b>bits</b>&lt;n&gt;</tt></dt>
Bill Wendling1a19af92008-02-12 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 Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]321
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]322<dt><tt><b>list</b>&lt;ty&gt;</tt></dt>
Bill Wendling1a19af92008-02-12 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 Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]325
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]326<dt>Class type</dt>
Bill Wendling1a19af92008-02-12 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 Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]332
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]333<dt><tt><b>dag</b></tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]334 <dd>This type represents a nestable directed graph of elements.</dd>
335
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]336<dt><tt><b>code</b></tt></dt>
Bill Wendling1a19af92008-02-12 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 Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]340
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]341<p>To date, these types have been sufficient for describing things that
342TableGen has been used for, but it is straight-forward to extend this list if
343needed.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]344
345</div>
346
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]347<!-- -------------------------------------------------------------------------->
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]348<div class="doc_subsubsection">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]349 <a name="values">TableGen values and expressions</a>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]350</div>
351
Misha Brukman94192b62004-06-03 16:59:59 +0000[diff] [blame]352<div class="doc_text">
353
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]354<p>TableGen allows for a pretty reasonable number of different expression forms
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]355when building up values. These forms allow the TableGen file to be written in a
356natural syntax and flavor for the application. The current expression forms
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]357supported include:</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]358
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]359<dl>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]360<dt><tt>?</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]361 <dd>uninitialized field</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]362<dt><tt>0b1001011</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]363 <dd>binary integer value</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]364<dt><tt>07654321</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]365 <dd>octal integer value (indicated by a leading 0)</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]366<dt><tt>7</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]367 <dd>decimal integer value</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]368<dt><tt>0x7F</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]369 <dd>hexadecimal integer value</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]370<dt><tt>"foo"</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]371 <dd>string value</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]372<dt><tt>[{ ... }]</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]373 <dd>code fragment</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]374<dt><tt>[ X, Y, Z ]</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]375 <dd>list value.</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]376<dt><tt>{ a, b, c }</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]377 <dd>initializer for a "bits&lt;3&gt;" value</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]378<dt><tt>value</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]379 <dd>value reference</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]380<dt><tt>value{17}</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]381 <dd>access to one bit of a value</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]382<dt><tt>value{15-17}</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]383 <dd>access to multiple bits of a value</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]384<dt><tt>DEF</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]385 <dd>reference to a record definition</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]386<dt><tt>CLASS&lt;val list&gt;</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]387 <dd>reference to a new anonymous definition of CLASS with the specified
388 template arguments.</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]389<dt><tt>X.Y</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]390 <dd>reference to the subfield of a value</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]391<dt><tt>list[4-7,17,2-3]</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]392 <dd>A slice of the 'list' list, including elements 4,5,6,7,17,2, and 3 from
393 it. Elements may be included multiple times.</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]394<dt><tt>(DEF a, b)</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]395 <dd>a dag value. The first element is required to be a record definition, the
396 remaining elements in the list may be arbitrary other values, including nested
397 `<tt>dag</tt>' values.</dd>
Bill Wendling8402d022008-02-12 07:09:05 +0000[diff] [blame]398<dt><tt>!strconcat(a, b)</tt></dt>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]399 <dd>A string value that is the result of concatenating the 'a' and 'b'
400 strings.</dd>
401</dl>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]402
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]403<p>Note that all of the values have rules specifying how they convert to values
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]404for different types. These rules allow you to assign a value like "<tt>7</tt>"
405to a "<tt>bits&lt;4&gt;</tt>" value, for example.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]406
407</div>
408
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]409<!-- ======================================================================= -->
Misha Brukman94192b62004-06-03 16:59:59 +0000[diff] [blame]410<div class="doc_subsection">
411 <a name="classesdefs">Classes and definitions</a>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]412</div>
413
Misha Brukman94192b62004-06-03 16:59:59 +0000[diff] [blame]414<div class="doc_text">
415
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]416<p>As mentioned in the <a href="#concepts">intro</a>, classes and definitions
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]417(collectively known as 'records') in TableGen are the main high-level unit of
418information that TableGen collects. Records are defined with a <tt>def</tt> or
419<tt>class</tt> keyword, the record name, and an optional list of "<a
Misha Brukman31551592004-06-03 23:42:24 +0000[diff] [blame]420href="#templateargs">template arguments</a>". If the record has superclasses,
Jeff Cohendd24d7c2005-10-24 16:54:55 +0000[diff] [blame]421they are specified as a comma separated list that starts with a colon character
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]422("<tt>:</tt>"). If <a href="#valuedef">value definitions</a> or <a
423href="#recordlet">let expressions</a> are needed for the class, they are
424enclosed in curly braces ("<tt>{}</tt>"); otherwise, the record ends with a
425semicolon.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]426
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]427<p>Here is a simple TableGen file:</p>
428
429<div class="doc_code">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]430<pre>
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]431<b>class</b> C { <b>bit</b> V = 1; }
432<b>def</b> X : C;
433<b>def</b> Y : C {
434 <b>string</b> Greeting = "hello";
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]435}
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]436</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]437</div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]438
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]439<p>This example defines two definitions, <tt>X</tt> and <tt>Y</tt>, both of
440which derive from the <tt>C</tt> class. Because of this, they both get the
441<tt>V</tt> bit value. The <tt>Y</tt> definition also gets the Greeting member
442as well.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]443
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]444<p>In general, classes are useful for collecting together the commonality
445between a group of records and isolating it in a single place. Also, classes
446permit the specification of default values for their subclasses, allowing the
447subclasses to override them as they wish.</p>
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]448
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]449</div>
450
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]451<!---------------------------------------------------------------------------->
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]452<div class="doc_subsubsection">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]453 <a name="valuedef">Value definitions</a>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]454</div>
455
456<div class="doc_text">
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]457
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]458<p>Value definitions define named entries in records. A value must be defined
John Criswell407f6d42004-02-12 18:11:53 +0000[diff] [blame]459before it can be referred to as the operand for another value definition or
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]460before the value is reset with a <a href="#recordlet">let expression</a>. A
461value is defined by specifying a <a href="#types">TableGen type</a> and a name.
462If an initial value is available, it may be specified after the type with an
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]463equal sign. Value definitions require terminating semicolons.</p>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]464
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]465</div>
466
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]467<!-- -------------------------------------------------------------------------->
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]468<div class="doc_subsubsection">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]469 <a name="recordlet">'let' expressions</a>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]470</div>
471
472<div class="doc_text">
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]473
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]474<p>A record-level let expression is used to change the value of a value
475definition in a record. This is primarily useful when a superclass defines a
476value that a derived class or definition wants to override. Let expressions
477consist of the '<tt>let</tt>' keyword followed by a value name, an equal sign
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]478("<tt>=</tt>"), and a new value. For example, a new class could be added to the
479example above, redefining the <tt>V</tt> field for all of its subclasses:</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]480
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]481<div class="doc_code">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]482<pre>
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]483<b>class</b> D : C { let V = 0; }
484<b>def</b> Z : D;
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]485</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]486</div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]487
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]488<p>In this case, the <tt>Z</tt> definition will have a zero value for its "V"
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]489value, despite the fact that it derives (indirectly) from the <tt>C</tt> class,
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]490because the <tt>D</tt> class overrode its value.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]491
492</div>
493
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]494<!-- -------------------------------------------------------------------------->
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]495<div class="doc_subsubsection">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]496 <a name="templateargs">Class template arguments</a>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]497</div>
498
499<div class="doc_text">
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]500
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]501<p>TableGen permits the definition of parameterized classes as well as normal
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]502concrete classes. Parameterized TableGen classes specify a list of variable
503bindings (which may optionally have defaults) that are bound when used. Here is
504a simple example:</p>
505
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]506<div class="doc_code">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]507<pre>
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]508<b>class</b> FPFormat&lt;<b>bits</b>&lt;3&gt; val&gt; {
509 <b>bits</b>&lt;3&gt; Value = val;
510}
511<b>def</b> NotFP : FPFormat&lt;0&gt;;
512<b>def</b> ZeroArgFP : FPFormat&lt;1&gt;;
513<b>def</b> OneArgFP : FPFormat&lt;2&gt;;
514<b>def</b> OneArgFPRW : FPFormat&lt;3&gt;;
515<b>def</b> TwoArgFP : FPFormat&lt;4&gt;;
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]516<b>def</b> CompareFP : FPFormat&lt;5&gt;;
517<b>def</b> CondMovFP : FPFormat&lt;6&gt;;
518<b>def</b> SpecialFP : FPFormat&lt;7&gt;;
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]519</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]520</div>
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]521
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]522<p>In this case, template arguments are used as a space efficient way to specify
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]523a list of "enumeration values", each with a "<tt>Value</tt>" field set to the
524specified integer.</p>
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]525
526<p>The more esoteric forms of <a href="#values">TableGen expressions</a> are
527useful in conjunction with template arguments. As an example:</p>
528
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]529<div class="doc_code">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]530<pre>
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]531<b>class</b> ModRefVal&lt;<b>bits</b>&lt;2&gt; val&gt; {
532 <b>bits</b>&lt;2&gt; Value = val;
533}
534
535<b>def</b> None : ModRefVal&lt;0&gt;;
536<b>def</b> Mod : ModRefVal&lt;1&gt;;
537<b>def</b> Ref : ModRefVal&lt;2&gt;;
538<b>def</b> ModRef : ModRefVal&lt;3&gt;;
539
540<b>class</b> Value&lt;ModRefVal MR&gt; {
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]541 <i>// Decode some information into a more convenient format, while providing
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]542 // a nice interface to the user of the "Value" class.</i>
543 <b>bit</b> isMod = MR.Value{0};
544 <b>bit</b> isRef = MR.Value{1};
545
546 <i>// other stuff...</i>
547}
548
549<i>// Example uses</i>
550<b>def</b> bork : Value&lt;Mod&gt;;
551<b>def</b> zork : Value&lt;Ref&gt;;
552<b>def</b> hork : Value&lt;ModRef&gt;;
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]553</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]554</div>
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]555
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]556<p>This is obviously a contrived example, but it shows how template arguments
557can be used to decouple the interface provided to the user of the class from the
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]558actual internal data representation expected by the class. In this case,
559running <tt>tblgen</tt> on the example prints the following definitions:</p>
560
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]561<div class="doc_code">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]562<pre>
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]563<b>def</b> bork { <i>// Value</i>
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]564 <b>bit</b> isMod = 1;
565 <b>bit</b> isRef = 0;
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]566}
567<b>def</b> hork { <i>// Value</i>
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]568 <b>bit</b> isMod = 1;
569 <b>bit</b> isRef = 1;
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]570}
571<b>def</b> zork { <i>// Value</i>
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]572 <b>bit</b> isMod = 0;
573 <b>bit</b> isRef = 1;
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]574}
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]575</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]576</div>
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]577
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]578<p> This shows that TableGen was able to dig into the argument and extract a
579piece of information that was requested by the designer of the "Value" class.
580For more realistic examples, please see existing users of TableGen, such as the
581X86 backend.</p>
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]582
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]583</div>
584
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]585<!-- -------------------------------------------------------------------------->
586<div class="doc_subsubsection">
587 <a name="multiclass">Multiclass definitions and instances</a>
588</div>
589
590<div class="doc_text">
591
592<p>
593While classes with template arguments are a good way to factor commonality
594between two instances of a definition, multiclasses allow a convenient notation
595for defining multiple definitions at once (instances of implicitly constructed
596classes). For example, consider an 3-address instruction set whose instructions
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]597come in two forms: "<tt>reg = reg op reg</tt>" and "<tt>reg = reg op imm</tt>"
598(e.g. SPARC). In this case, you'd like to specify in one place that this
599commonality exists, then in a separate place indicate what all the ops are.
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]600</p>
601
602<p>
603Here is an example TableGen fragment that shows this idea:
604</p>
605
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]606<div class="doc_code">
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]607<pre>
608<b>def</b> ops;
609<b>def</b> GPR;
610<b>def</b> Imm;
611<b>class</b> inst&lt;<b>int</b> opc, <b>string</b> asmstr, <b>dag</b> operandlist&gt;;
612
613<b>multiclass</b> ri_inst&lt;<b>int</b> opc, <b>string</b> asmstr&gt; {
614 def _rr : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
615 (ops GPR:$dst, GPR:$src1, GPR:$src2)&gt;;
616 def _ri : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
617 (ops GPR:$dst, GPR:$src1, Imm:$src2)&gt;;
618}
619
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]620<i>// Instantiations of the ri_inst multiclass.</i>
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]621<b>defm</b> ADD : ri_inst&lt;0b111, "add"&gt;;
622<b>defm</b> SUB : ri_inst&lt;0b101, "sub"&gt;;
623<b>defm</b> MUL : ri_inst&lt;0b100, "mul"&gt;;
624...
625</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]626</div>
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]627
Chris Lattner28368122006-09-01 22:01:36 +0000[diff] [blame]628<p>The name of the resultant definitions has the multidef fragment names
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]629 appended to them, so this defines <tt>ADD_rr</tt>, <tt>ADD_ri</tt>,
630 <tt>SUB_rr</tt>, etc. Using a multiclass this way is exactly equivalent to
631 instantiating the classes multiple times yourself, e.g. by writing:</p>
632
633<div class="doc_code">
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]634<pre>
635<b>def</b> ops;
636<b>def</b> GPR;
637<b>def</b> Imm;
638<b>class</b> inst&lt;<b>int</b> opc, <b>string</b> asmstr, <b>dag</b> operandlist&gt;;
639
640<b>class</b> rrinst&lt;<b>int</b> opc, <b>string</b> asmstr&gt;
641 : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
642 (ops GPR:$dst, GPR:$src1, GPR:$src2)&gt;;
643
644<b>class</b> riinst&lt;<b>int</b> opc, <b>string</b> asmstr&gt;
645 : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
646 (ops GPR:$dst, GPR:$src1, Imm:$src2)&gt;;
647
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]648<i>// Instantiations of the ri_inst multiclass.</i>
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]649<b>def</b> ADD_rr : rrinst&lt;0b111, "add"&gt;;
650<b>def</b> ADD_ri : riinst&lt;0b111, "add"&gt;;
651<b>def</b> SUB_rr : rrinst&lt;0b101, "sub"&gt;;
652<b>def</b> SUB_ri : riinst&lt;0b101, "sub"&gt;;
653<b>def</b> MUL_rr : rrinst&lt;0b100, "mul"&gt;;
654<b>def</b> MUL_ri : riinst&lt;0b100, "mul"&gt;;
655...
656</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]657</div>
Chris Lattnerf01a85b2006-09-01 21:44:18 +0000[diff] [blame]658
659</div>
660
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]661<!-- ======================================================================= -->
662<div class="doc_subsection">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]663 <a name="filescope">File scope entities</a>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]664</div>
665
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]666<!-- -------------------------------------------------------------------------->
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]667<div class="doc_subsubsection">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]668 <a name="include">File inclusion</a>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]669</div>
670
671<div class="doc_text">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]672<p>TableGen supports the '<tt>include</tt>' token, which textually substitutes
673the specified file in place of the include directive. The filename should be
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]674specified as a double quoted string immediately after the '<tt>include</tt>'
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]675keyword. Example:</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]676
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]677<div class="doc_code">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]678<pre>
Chris Lattner55927232004-02-06 06:37:00 +0000[diff] [blame]679<b>include</b> "foo.td"
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]680</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]681</div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]682
683</div>
684
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]685<!-- -------------------------------------------------------------------------->
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]686<div class="doc_subsubsection">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]687 <a name="globallet">'let' expressions</a>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]688</div>
689
690<div class="doc_text">
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]691
692<p>"Let" expressions at file scope are similar to <a href="#recordlet">"let"
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]693expressions within a record</a>, except they can specify a value binding for
694multiple records at a time, and may be useful in certain other cases.
695File-scope let expressions are really just another way that TableGen allows the
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]696end-user to factor out commonality from the records.</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]697
Jeff Cohendd24d7c2005-10-24 16:54:55 +0000[diff] [blame]698<p>File-scope "let" expressions take a comma-separated list of bindings to
Matthijs Kooijman3abb3082008-10-20 08:45:34 +0000[diff] [blame]699apply, and one or more records to bind the values in. Here are some
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]700examples:</p>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]701
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]702<div class="doc_code">
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]703<pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]704<b>let</b> isTerminator = 1, isReturn = 1, isBarrier = 1, hasCtrlDep = 1 <b>in</b>
705 <b>def</b> RET : I&lt;0xC3, RawFrm, (outs), (ins), "ret", [(X86retflag 0)]&gt;;
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]706
Chris Lattner1215e322004-02-06 06:04:25 +0000[diff] [blame]707<b>let</b> isCall = 1 <b>in</b>
708 <i>// All calls clobber the non-callee saved registers...</i>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]709 <b>let</b> Defs = [EAX, ECX, EDX, FP0, FP1, FP2, FP3, FP4, FP5, FP6, ST0,
710 MM0, MM1, MM2, MM3, MM4, MM5, MM6, MM7,
711 XMM0, XMM1, XMM2, XMM3, XMM4, XMM5, XMM6, XMM7, EFLAGS] <b>in</b> {
Dan Gohman2ed27532008-10-14 17:00:38 +0000[diff] [blame]712 <b>def</b> CALLpcrel32 : Ii32&lt;0xE8, RawFrm, (outs), (ins i32imm:$dst,variable_ops),
713 "call\t${dst:call}", []&gt;;
714 <b>def</b> CALL32r : I&lt;0xFF, MRM2r, (outs), (ins GR32:$dst, variable_ops),
715 "call\t{*}$dst", [(X86call GR32:$dst)]&gt;;
716 <b>def</b> CALL32m : I&lt;0xFF, MRM2m, (outs), (ins i32mem:$dst, variable_ops),
717 "call\t{*}$dst", []&gt;;
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]718 }
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]719</pre>
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]720</div>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]721
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]722<p>File-scope "let" expressions are often useful when a couple of definitions
723need to be added to several records, and the records do not otherwise need to be
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]724opened, as in the case with the <tt>CALL*</tt> instructions above.</p>
725
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]726</div>
727
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]728<!-- *********************************************************************** -->
729<div class="doc_section"><a name="backends">TableGen backends</a></div>
730<!-- *********************************************************************** -->
731
732<div class="doc_text">
Bill Wendling1a19af92008-02-12 07:06:19 +0000[diff] [blame]733
734<p>TODO: How they work, how to write one. This section should not contain
735details about any particular backend, except maybe -print-enums as an example.
736This should highlight the APIs in <tt>TableGen/Record.h</tt>.</p>
737
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]738</div>
739
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]740<!-- *********************************************************************** -->
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]741
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]742<hr>
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]743<address>
744 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman86242e12008-12-11 17:34:48 +0000[diff] [blame]745 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]746 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman86242e12008-12-11 17:34:48 +0000[diff] [blame]747 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]748
749 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencerca058542006-03-14 05:39:39 +0000[diff] [blame]750 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]751 Last modified: $Date$
Misha Brukman692cec02004-05-12 18:31:21 +0000[diff] [blame]752</address>
Chris Lattner149a2492004-02-06 05:42:53 +0000[diff] [blame]753
754</body>
755</html>