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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 Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]12<div class="doc_text">
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]13<ul>
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]14 <li><a href="#introduction">Introduction</a>
Chris Lattner61dfc412004-02-06 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 Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]19 </ol></li>
20 <li><a href="#syntax">TableGen syntax</a>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]21 <ol>
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]22 <li><a href="#primitives">TableGen primitives</a>
Chris Lattner61dfc412004-02-06 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 Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]27 </ol></li>
28 <li><a href="#classesdefs">Classes and definitions</a>
Chris Lattner61dfc412004-02-06 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 Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]33 <li><a href="#multiclass">Multiclass definitions and instances</a></li>
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]34 </ol></li>
35 <li><a href="#filescope">File scope entities</a>
Chris Lattner61dfc412004-02-06 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 Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]39 </ol></li>
40 </ol></li>
41 <li><a href="#backends">TableGen backends</a>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]42 <ol>
Chris Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]43 <li><a href="#">todo</a></li>
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]44 </ol></li>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]45</ul>
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]46</div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]47
Chris Lattner27bc6532004-05-23 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 Lattner61dfc412004-02-06 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 Lattner4e7a9e62004-07-26 21:16:55 +0000[diff] [blame]68of TableGen is the <a href="CodeGenerator.html">LLVM code generator</a>.</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]69
Misha Brukman573bf382004-05-12 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 Wendlingc8237022008-02-12 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 Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]73distribution, respectively.</p>
Chris Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]74
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]75</div>
76
77<!-- ======================================================================= -->
Jim Laskey6b3b4232006-09-09 09:10:37 +0000[diff] [blame]78<div class="doc_subsection"><a name="concepts">Basic concepts</a></div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]79
80<div class="doc_text">
81
Misha Brukman573bf382004-05-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]84
Misha Brukman573bf382004-05-12 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 Wendlingc8237022008-02-12 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 Lattner61dfc412004-02-06 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 Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]90taken care of and are fixed by TableGen.</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]91
Misha Brukman573bf382004-05-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]95
Misha Brukman573bf382004-05-12 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 Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]98abstractions for either the domain they are targeting (such as "Register",
Misha Brukman573bf382004-05-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]105
Chris Lattner8405d992006-09-01 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]110</div>
111
112<!-- ======================================================================= -->
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]113<div class="doc_subsection"><a name="example">An example record</a></div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]114
115<div class="doc_text">
116
Misha Brukman573bf382004-05-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]121
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]122<div class="doc_code">
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]123<pre>
124...
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]125<b>def</b> ADD32rr { <i>// Instruction X86Inst I</i>
Chris Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]126 <b>string</b> Namespace = "X86";
Bill Wendlingc8237022008-02-12 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 Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]131 <b>list</b>&lt;Register&gt; Uses = [];
Bill Wendlingc8237022008-02-12 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 Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]136 <b>bit</b> isReturn = 0;
137 <b>bit</b> isBranch = 0;
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]138 <b>bit</b> isIndirectBranch = 0;
139 <b>bit</b> isBarrier = 0;
Chris Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]140 <b>bit</b> isCall = 0;
Bill Wendlingc8237022008-02-12 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 Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]145 <b>bit</b> isTwoAddress = 1;
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]146 <b>bit</b> isConvertibleToThreeAddress = 1;
147 <b>bit</b> isCommutable = 1;
Chris Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]148 <b>bit</b> isTerminator = 0;
Bill Wendlingc8237022008-02-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]162 Format Form = MRMDestReg;
Bill Wendlingc8237022008-02-12 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 Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]166 <b>bit</b> hasOpSizePrefix = 0;
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]167 <b>bit</b> hasAdSizePrefix = 0;
Chris Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]168 <b>bits</b>&lt;4&gt; Prefix = { 0, 0, 0, 0 };
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]169 <b>bit</b> hasREX_WPrefix = 0;
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]170 FPFormat FPForm = ?;
Chris Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]171 <b>bits</b>&lt;3&gt; FPFormBits = { 0, 0, 0 };
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]172}
173...
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]174</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]175</div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]176
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]177<p>This definition corresponds to a 32-bit register-register add instruction in
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]178the X86. The string after the '<tt>def</tt>' string indicates the name of the
Bill Wendlingc8237022008-02-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]187
Misha Brukman573bf382004-05-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]193
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]194<div class="doc_code">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]195<pre>
Bill Wendlingc8237022008-02-12 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 Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]203</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]204</div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]205
Bill Wendlingc8237022008-02-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]211
212</div>
213
214<!-- ======================================================================= -->
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]215<div class="doc_subsection"><a name="running">Running TableGen</a></div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]216
217<div class="doc_text">
218
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]219<p>TableGen runs just like any other LLVM tool. The first (optional) argument
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]220specifies the file to read. If a filename is not specified, <tt>tblgen</tt>
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]221reads from standard input.</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]222
Misha Brukman573bf382004-05-12 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 Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]225-help</tt>' for a list). For example, to get a list of all of the definitions
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]226that subclass a particular type (which can be useful for building up an enum
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]227list of these records), use the <tt>-print-enums</tt> option:</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]228
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]229<div class="doc_code">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]230<pre>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]231$ tblgen X86.td -print-enums -class=Register
Bill Wendlingc8237022008-02-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]240
241$ tblgen X86.td -print-enums -class=Instruction
Bill Wendlingc8237022008-02-12 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 Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]247</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]248</div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]249
Misha Brukman573bf382004-05-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]252
Bill Wendlingc8237022008-02-12 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 Lattner61dfc412004-02-06 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 Wendlingc8237022008-02-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]268This section describes the syntax and the constructs allowed in a TableGen file.
269</p>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]270
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]271</div>
272
273<!-- ======================================================================= -->
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]274<div class="doc_subsection"><a name="primitives">TableGen primitives</a></div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]275
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]276<!-- -------------------------------------------------------------------------->
277<div class="doc_subsubsection"><a name="comments">TableGen comments</a></div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]278
279<div class="doc_text">
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]280
Chris Lattner61dfc412004-02-06 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 Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]283
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]284</div>
285
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]286<!-- -------------------------------------------------------------------------->
Misha Brukmanda976802004-06-03 16:59:59 +0000[diff] [blame]287<div class="doc_subsubsection">
288 <a name="types">The TableGen type system</a>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]289</div>
290
291<div class="doc_text">
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]292
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]293<p>TableGen files are strongly typed, in a simple (but complete) type-system.
Chris Lattner61dfc412004-02-06 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 Brukman573bf382004-05-12 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 Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]303
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]304<dl>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]305<dt><tt><b>bit</b></tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]306 <dd>A 'bit' is a boolean value that can hold either 0 or 1.</dd>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]307
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]308<dt><tt><b>int</b></tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]309 <dd>The 'int' type represents a simple 32-bit integer value, such as 5.</dd>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]310
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]311<dt><tt><b>string</b></tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]312 <dd>The 'string' type represents an ordered sequence of characters of
313 arbitrary length.</dd>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]314
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]315<dt><tt><b>bits</b>&lt;n&gt;</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]316 <dd>A 'bits' type is an arbitrary, but fixed, size integer that is broken up
317 into individual bits. This type is useful because it can handle some bits
318 being defined while others are undefined.</dd>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]319
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]320<dt><tt><b>list</b>&lt;ty&gt;</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]321 <dd>This type represents a list whose elements are some other type. The
322 contained type is arbitrary: it can even be another list type.</dd>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]323
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]324<dt>Class type</dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]325 <dd>Specifying a class name in a type context means that the defined value
326 must be a subclass of the specified class. This is useful in conjunction with
327 the <b><tt>list</tt></b> type, for example, to constrain the elements of the
328 list to a common base class (e.g., a <tt><b>list</b>&lt;Register&gt;</tt> can
329 only contain definitions derived from the "<tt>Register</tt>" class).</dd>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]330
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]331<dt><tt><b>dag</b></tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]332 <dd>This type represents a nestable directed graph of elements.</dd>
333
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]334<dt><tt><b>code</b></tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]335 <dd>This represents a big hunk of text. NOTE: I don't remember why this is
336 distinct from string!</dd>
337</dl>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]338
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]339<p>To date, these types have been sufficient for describing things that
340TableGen has been used for, but it is straight-forward to extend this list if
341needed.</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]342
343</div>
344
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]345<!-- -------------------------------------------------------------------------->
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]346<div class="doc_subsubsection">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]347 <a name="values">TableGen values and expressions</a>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]348</div>
349
Misha Brukmanda976802004-06-03 16:59:59 +0000[diff] [blame]350<div class="doc_text">
351
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]352<p>TableGen allows for a pretty reasonable number of different expression forms
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]353when building up values. These forms allow the TableGen file to be written in a
354natural syntax and flavor for the application. The current expression forms
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]355supported include:</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]356
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]357<dl>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]358<dt><tt>?</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]359 <dd>uninitialized field</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]360<dt><tt>0b1001011</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]361 <dd>binary integer value</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]362<dt><tt>07654321</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]363 <dd>octal integer value (indicated by a leading 0)</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]364<dt><tt>7</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]365 <dd>decimal integer value</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]366<dt><tt>0x7F</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]367 <dd>hexadecimal integer value</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]368<dt><tt>"foo"</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]369 <dd>string value</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]370<dt><tt>[{ ... }]</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]371 <dd>code fragment</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]372<dt><tt>[ X, Y, Z ]</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]373 <dd>list value.</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]374<dt><tt>{ a, b, c }</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]375 <dd>initializer for a "bits&lt;3&gt;" value</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]376<dt><tt>value</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]377 <dd>value reference</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]378<dt><tt>value{17}</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]379 <dd>access to one bit of a value</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]380<dt><tt>value{15-17}</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]381 <dd>access to multiple bits of a value</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]382<dt><tt>DEF</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]383 <dd>reference to a record definition</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]384<dt><tt>CLASS&lt;val list&gt;</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]385 <dd>reference to a new anonymous definition of CLASS with the specified
386 template arguments.</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]387<dt><tt>X.Y</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]388 <dd>reference to the subfield of a value</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]389<dt><tt>list[4-7,17,2-3]</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]390 <dd>A slice of the 'list' list, including elements 4,5,6,7,17,2, and 3 from
391 it. Elements may be included multiple times.</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]392<dt><tt>(DEF a, b)</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]393 <dd>a dag value. The first element is required to be a record definition, the
394 remaining elements in the list may be arbitrary other values, including nested
395 `<tt>dag</tt>' values.</dd>
Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]396<dt><tt>!strconcat(a, b)</tt></dt>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]397 <dd>A string value that is the result of concatenating the 'a' and 'b'
398 strings.</dd>
399</dl>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]400
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]401<p>Note that all of the values have rules specifying how they convert to values
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]402for different types. These rules allow you to assign a value like "<tt>7</tt>"
403to a "<tt>bits&lt;4&gt;</tt>" value, for example.</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]404
405</div>
406
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]407<!-- ======================================================================= -->
Misha Brukmanda976802004-06-03 16:59:59 +0000[diff] [blame]408<div class="doc_subsection">
409 <a name="classesdefs">Classes and definitions</a>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]410</div>
411
Misha Brukmanda976802004-06-03 16:59:59 +0000[diff] [blame]412<div class="doc_text">
413
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]414<p>As mentioned in the <a href="#concepts">intro</a>, classes and definitions
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]415(collectively known as 'records') in TableGen are the main high-level unit of
416information that TableGen collects. Records are defined with a <tt>def</tt> or
417<tt>class</tt> keyword, the record name, and an optional list of "<a
Misha Brukman009e2dd2004-06-03 23:42:24 +0000[diff] [blame]418href="#templateargs">template arguments</a>". If the record has superclasses,
Jeff Cohen64db9962005-10-24 16:54:55 +0000[diff] [blame]419they are specified as a comma separated list that starts with a colon character
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]420("<tt>:</tt>"). If <a href="#valuedef">value definitions</a> or <a
421href="#recordlet">let expressions</a> are needed for the class, they are
422enclosed in curly braces ("<tt>{}</tt>"); otherwise, the record ends with a
423semicolon.</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]424
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]425<p>Here is a simple TableGen file:</p>
426
427<div class="doc_code">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]428<pre>
Chris Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]429<b>class</b> C { <b>bit</b> V = 1; }
430<b>def</b> X : C;
431<b>def</b> Y : C {
432 <b>string</b> Greeting = "hello";
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]433}
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]434</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]435</div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]436
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]437<p>This example defines two definitions, <tt>X</tt> and <tt>Y</tt>, both of
438which derive from the <tt>C</tt> class. Because of this, they both get the
439<tt>V</tt> bit value. The <tt>Y</tt> definition also gets the Greeting member
440as well.</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]441
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]442<p>In general, classes are useful for collecting together the commonality
443between a group of records and isolating it in a single place. Also, classes
444permit the specification of default values for their subclasses, allowing the
445subclasses to override them as they wish.</p>
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]446
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]447</div>
448
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]449<!---------------------------------------------------------------------------->
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]450<div class="doc_subsubsection">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]451 <a name="valuedef">Value definitions</a>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]452</div>
453
454<div class="doc_text">
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]455
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]456<p>Value definitions define named entries in records. A value must be defined
John Criswell9c8b13e2004-02-12 18:11:53 +0000[diff] [blame]457before it can be referred to as the operand for another value definition or
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]458before the value is reset with a <a href="#recordlet">let expression</a>. A
459value is defined by specifying a <a href="#types">TableGen type</a> and a name.
460If an initial value is available, it may be specified after the type with an
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]461equal sign. Value definitions require terminating semicolons.</p>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]462
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]463</div>
464
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]465<!-- -------------------------------------------------------------------------->
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]466<div class="doc_subsubsection">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]467 <a name="recordlet">'let' expressions</a>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]468</div>
469
470<div class="doc_text">
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]471
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]472<p>A record-level let expression is used to change the value of a value
473definition in a record. This is primarily useful when a superclass defines a
474value that a derived class or definition wants to override. Let expressions
475consist of the '<tt>let</tt>' keyword followed by a value name, an equal sign
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]476("<tt>=</tt>"), and a new value. For example, a new class could be added to the
477example above, redefining the <tt>V</tt> field for all of its subclasses:</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]478
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]479<div class="doc_code">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]480<pre>
Chris Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]481<b>class</b> D : C { let V = 0; }
482<b>def</b> Z : D;
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]483</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]484</div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]485
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]486<p>In this case, the <tt>Z</tt> definition will have a zero value for its "V"
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]487value, despite the fact that it derives (indirectly) from the <tt>C</tt> class,
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]488because the <tt>D</tt> class overrode its value.</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]489
490</div>
491
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]492<!-- -------------------------------------------------------------------------->
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]493<div class="doc_subsubsection">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]494 <a name="templateargs">Class template arguments</a>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]495</div>
496
497<div class="doc_text">
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]498
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]499<p>TableGen permits the definition of parameterized classes as well as normal
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]500concrete classes. Parameterized TableGen classes specify a list of variable
501bindings (which may optionally have defaults) that are bound when used. Here is
502a simple example:</p>
503
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]504<div class="doc_code">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]505<pre>
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]506<b>class</b> FPFormat&lt;<b>bits</b>&lt;3&gt; val&gt; {
507 <b>bits</b>&lt;3&gt; Value = val;
508}
509<b>def</b> NotFP : FPFormat&lt;0&gt;;
510<b>def</b> ZeroArgFP : FPFormat&lt;1&gt;;
511<b>def</b> OneArgFP : FPFormat&lt;2&gt;;
512<b>def</b> OneArgFPRW : FPFormat&lt;3&gt;;
513<b>def</b> TwoArgFP : FPFormat&lt;4&gt;;
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]514<b>def</b> CompareFP : FPFormat&lt;5&gt;;
515<b>def</b> CondMovFP : FPFormat&lt;6&gt;;
516<b>def</b> SpecialFP : FPFormat&lt;7&gt;;
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]517</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]518</div>
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]519
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]520<p>In this case, template arguments are used as a space efficient way to specify
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]521a list of "enumeration values", each with a "<tt>Value</tt>" field set to the
522specified integer.</p>
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]523
524<p>The more esoteric forms of <a href="#values">TableGen expressions</a> are
525useful in conjunction with template arguments. As an example:</p>
526
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]527<div class="doc_code">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]528<pre>
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]529<b>class</b> ModRefVal&lt;<b>bits</b>&lt;2&gt; val&gt; {
530 <b>bits</b>&lt;2&gt; Value = val;
531}
532
533<b>def</b> None : ModRefVal&lt;0&gt;;
534<b>def</b> Mod : ModRefVal&lt;1&gt;;
535<b>def</b> Ref : ModRefVal&lt;2&gt;;
536<b>def</b> ModRef : ModRefVal&lt;3&gt;;
537
538<b>class</b> Value&lt;ModRefVal MR&gt; {
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]539 <i>// Decode some information into a more convenient format, while providing
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]540 // a nice interface to the user of the "Value" class.</i>
541 <b>bit</b> isMod = MR.Value{0};
542 <b>bit</b> isRef = MR.Value{1};
543
544 <i>// other stuff...</i>
545}
546
547<i>// Example uses</i>
548<b>def</b> bork : Value&lt;Mod&gt;;
549<b>def</b> zork : Value&lt;Ref&gt;;
550<b>def</b> hork : Value&lt;ModRef&gt;;
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]551</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]552</div>
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]553
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]554<p>This is obviously a contrived example, but it shows how template arguments
555can be used to decouple the interface provided to the user of the class from the
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]556actual internal data representation expected by the class. In this case,
557running <tt>tblgen</tt> on the example prints the following definitions:</p>
558
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]559<div class="doc_code">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]560<pre>
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]561<b>def</b> bork { <i>// Value</i>
Chris Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]562 <b>bit</b> isMod = 1;
563 <b>bit</b> isRef = 0;
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]564}
565<b>def</b> hork { <i>// Value</i>
Chris Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]566 <b>bit</b> isMod = 1;
567 <b>bit</b> isRef = 1;
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]568}
569<b>def</b> zork { <i>// Value</i>
Chris Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]570 <b>bit</b> isMod = 0;
571 <b>bit</b> isRef = 1;
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]572}
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]573</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]574</div>
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]575
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]576<p> This shows that TableGen was able to dig into the argument and extract a
577piece of information that was requested by the designer of the "Value" class.
578For more realistic examples, please see existing users of TableGen, such as the
579X86 backend.</p>
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]580
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]581</div>
582
Chris Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]583<!-- -------------------------------------------------------------------------->
584<div class="doc_subsubsection">
585 <a name="multiclass">Multiclass definitions and instances</a>
586</div>
587
588<div class="doc_text">
589
590<p>
591While classes with template arguments are a good way to factor commonality
592between two instances of a definition, multiclasses allow a convenient notation
593for defining multiple definitions at once (instances of implicitly constructed
594classes). For example, consider an 3-address instruction set whose instructions
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]595come in two forms: "<tt>reg = reg op reg</tt>" and "<tt>reg = reg op imm</tt>"
596(e.g. SPARC). In this case, you'd like to specify in one place that this
597commonality exists, then in a separate place indicate what all the ops are.
Chris Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]598</p>
599
600<p>
601Here is an example TableGen fragment that shows this idea:
602</p>
603
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]604<div class="doc_code">
Chris Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]605<pre>
606<b>def</b> ops;
607<b>def</b> GPR;
608<b>def</b> Imm;
609<b>class</b> inst&lt;<b>int</b> opc, <b>string</b> asmstr, <b>dag</b> operandlist&gt;;
610
611<b>multiclass</b> ri_inst&lt;<b>int</b> opc, <b>string</b> asmstr&gt; {
612 def _rr : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
613 (ops GPR:$dst, GPR:$src1, GPR:$src2)&gt;;
614 def _ri : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
615 (ops GPR:$dst, GPR:$src1, Imm:$src2)&gt;;
616}
617
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]618<i>// Instantiations of the ri_inst multiclass.</i>
Chris Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]619<b>defm</b> ADD : ri_inst&lt;0b111, "add"&gt;;
620<b>defm</b> SUB : ri_inst&lt;0b101, "sub"&gt;;
621<b>defm</b> MUL : ri_inst&lt;0b100, "mul"&gt;;
622...
623</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]624</div>
Chris Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]625
Chris Lattner9fc5e4c92006-09-01 22:01:36 +0000[diff] [blame]626<p>The name of the resultant definitions has the multidef fragment names
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]627 appended to them, so this defines <tt>ADD_rr</tt>, <tt>ADD_ri</tt>,
628 <tt>SUB_rr</tt>, etc. Using a multiclass this way is exactly equivalent to
629 instantiating the classes multiple times yourself, e.g. by writing:</p>
630
631<div class="doc_code">
Chris Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]632<pre>
633<b>def</b> ops;
634<b>def</b> GPR;
635<b>def</b> Imm;
636<b>class</b> inst&lt;<b>int</b> opc, <b>string</b> asmstr, <b>dag</b> operandlist&gt;;
637
638<b>class</b> rrinst&lt;<b>int</b> opc, <b>string</b> asmstr&gt;
639 : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
640 (ops GPR:$dst, GPR:$src1, GPR:$src2)&gt;;
641
642<b>class</b> riinst&lt;<b>int</b> opc, <b>string</b> asmstr&gt;
643 : inst&lt;opc, !strconcat(asmstr, " $dst, $src1, $src2"),
644 (ops GPR:$dst, GPR:$src1, Imm:$src2)&gt;;
645
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]646<i>// Instantiations of the ri_inst multiclass.</i>
Chris Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]647<b>def</b> ADD_rr : rrinst&lt;0b111, "add"&gt;;
648<b>def</b> ADD_ri : riinst&lt;0b111, "add"&gt;;
649<b>def</b> SUB_rr : rrinst&lt;0b101, "sub"&gt;;
650<b>def</b> SUB_ri : riinst&lt;0b101, "sub"&gt;;
651<b>def</b> MUL_rr : rrinst&lt;0b100, "mul"&gt;;
652<b>def</b> MUL_ri : riinst&lt;0b100, "mul"&gt;;
653...
654</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]655</div>
Chris Lattner8405d992006-09-01 21:44:18 +0000[diff] [blame]656
657</div>
658
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]659<!-- ======================================================================= -->
660<div class="doc_subsection">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]661 <a name="filescope">File scope entities</a>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]662</div>
663
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]664<!-- -------------------------------------------------------------------------->
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]665<div class="doc_subsubsection">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]666 <a name="include">File inclusion</a>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]667</div>
668
669<div class="doc_text">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]670<p>TableGen supports the '<tt>include</tt>' token, which textually substitutes
671the specified file in place of the include directive. The filename should be
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]672specified as a double quoted string immediately after the '<tt>include</tt>'
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]673keyword. Example:</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]674
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]675<div class="doc_code">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]676<pre>
Chris Lattner312f58d2004-02-06 06:37:00 +0000[diff] [blame]677<b>include</b> "foo.td"
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]678</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]679</div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]680
681</div>
682
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]683<!-- -------------------------------------------------------------------------->
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]684<div class="doc_subsubsection">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]685 <a name="globallet">'let' expressions</a>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]686</div>
687
688<div class="doc_text">
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]689
690<p>"Let" expressions at file scope are similar to <a href="#recordlet">"let"
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]691expressions within a record</a>, except they can specify a value binding for
692multiple records at a time, and may be useful in certain other cases.
693File-scope let expressions are really just another way that TableGen allows the
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]694end-user to factor out commonality from the records.</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]695
Jeff Cohen64db9962005-10-24 16:54:55 +0000[diff] [blame]696<p>File-scope "let" expressions take a comma-separated list of bindings to
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]697apply, and one of more records to bind the values in. Here are some
698examples:</p>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]699
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]700<div class="doc_code">
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]701<pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]702<b>let</b> isTerminator = 1, isReturn = 1, isBarrier = 1, hasCtrlDep = 1 <b>in</b>
703 <b>def</b> RET : I&lt;0xC3, RawFrm, (outs), (ins), "ret", [(X86retflag 0)]&gt;;
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]704
Chris Lattner89bbdb72004-02-06 06:04:25 +0000[diff] [blame]705<b>let</b> isCall = 1 <b>in</b>
706 <i>// All calls clobber the non-callee saved registers...</i>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]707 <b>let</b> Defs = [EAX, ECX, EDX, FP0, FP1, FP2, FP3, FP4, FP5, FP6, ST0,
708 MM0, MM1, MM2, MM3, MM4, MM5, MM6, MM7,
709 XMM0, XMM1, XMM2, XMM3, XMM4, XMM5, XMM6, XMM7, EFLAGS] <b>in</b> {
710 <b>def</b> CALLpcrel32 : Ii32<0xE8, RawFrm, (outs), (ins i32imm:$dst,variable_ops),
711 "call\t${dst:call}", []>;
712 <b>def</b> CALL32r : I<0xFF, MRM2r, (outs), (ins GR32:$dst, variable_ops),
713 "call\t{*}$dst", [(X86call GR32:$dst)]>;
714 <b>def</b> CALL32m : I<0xFF, MRM2m, (outs), (ins i32mem:$dst, variable_ops),
715 "call\t{*}$dst", []>;
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]716 }
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]717</pre>
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]718</div>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]719
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]720<p>File-scope "let" expressions are often useful when a couple of definitions
721need to be added to several records, and the records do not otherwise need to be
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]722opened, as in the case with the <tt>CALL*</tt> instructions above.</p>
723
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]724</div>
725
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]726<!-- *********************************************************************** -->
727<div class="doc_section"><a name="backends">TableGen backends</a></div>
728<!-- *********************************************************************** -->
729
730<div class="doc_text">
Bill Wendlingc8237022008-02-12 07:06:19 +0000[diff] [blame]731
732<p>TODO: How they work, how to write one. This section should not contain
733details about any particular backend, except maybe -print-enums as an example.
734This should highlight the APIs in <tt>TableGen/Record.h</tt>.</p>
735
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]736</div>
737
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]738<!-- *********************************************************************** -->
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]739
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]740<hr>
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]741<address>
742 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
743 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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Bill Wendling9f52cb72008-02-12 07:09:05 +0000[diff] [blame]745 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]746
747 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencerc2adb2a2006-03-14 05:39:39 +0000[diff] [blame]748 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]749 Last modified: $Date$
Misha Brukman573bf382004-05-12 18:31:21 +0000[diff] [blame]750</address>
Chris Lattner61dfc412004-02-06 05:42:53 +0000[diff] [blame]751
752</body>
753</html>