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17<body>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]18<div class="doc_title"> LLVM Bytecode File Format </div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]19<ol>
20 <li><a href="#abstract">Abstract</a></li>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]21 <li><a href="#concepts">Concepts</a>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]22 <ol>
23 <li><a href="#blocks">Blocks</a></li>
24 <li><a href="#lists">Lists</a></li>
25 <li><a href="#fields">Fields</a></li>
26 <li><a href="#align">Alignment</a></li>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]27 <li><a href="#vbr">Variable Bit-Rate Encoding</a></li>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]28 <li><a href="#encoding">Encoding Primitives</a></li>
29 <li><a href="#slots">Slots</a></li>
30 </ol>
31 </li>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]32 <li><a href="#general">General Structure</a> </li>
33 <li><a href="#blockdefs">Block Definitions</a>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]34 <ol>
Reid Spencerb39021b2004-05-23 17:05:09 +0000[diff] [blame]35 <li><a href="#signature">Signature Block</a></li>
36 <li><a href="#module">Module Block</a></li>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]37 <li><a href="#globaltypes">Global Type Pool</a></li>
38 <li><a href="#globalinfo">Module Info Block</a></li>
39 <li><a href="#constantpool">Global Constant Pool</a></li>
40 <li><a href="#functiondefs">Function Definition</a></li>
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]41 <li><a href="#instructionlist">Instructions List</a></li>
42 <li><a href="#instructions">Instructions</a></li>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]43 <li><a href="#symtab">Symbol Table</a></li>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]44 </ol>
45 </li>
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]46 <li><a href="#versiondiffs">Version Differences</a>
47 <ol>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]48 <li><a href="#vers13">Version 1.3 Differences From 1.4</a></li>
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]49 <li><a href="#vers12">Version 1.2 Differences From 1.3</a></li>
50 <li><a href="#vers11">Version 1.1 Differences From 1.2</a></li>
51 <li><a href="#vers10">Version 1.0 Differences From 1.1</a></li>
52 </ol>
53 </li>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]54</ol>
Chris Lattner8dabb502004-05-25 17:44:58 +0000[diff] [blame]55<div class="doc_author">
56<p>Written by <a href="mailto:rspencer@x10sys.com">Reid Spencer</a>
57</p>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]58</div>
59<!-- *********************************************************************** -->
60<div class="doc_section"> <a name="abstract">Abstract </a></div>
61<!-- *********************************************************************** -->
62<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]63<p>This document describes the LLVM bytecode file format. It specifies
64the binary encoding rules of the bytecode file format so that
65equivalent systems can encode bytecode files correctly. The LLVM
66bytecode representation is used to store the intermediate
67representation on disk in compacted form.</p>
68<p>The LLVM bytecode format may change in the future, but LLVM will
69always be backwards compatible with older formats. This document will
70only describe the most current version of the bytecode format. See <a
71 href="#versiondiffs">Version Differences</a> for the details on how
72the current version is different from previous versions.</p>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]73</div>
74<!-- *********************************************************************** -->
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]75<div class="doc_section"> <a name="concepts">Concepts</a> </div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]76<!-- *********************************************************************** -->
77<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]78<p>This section describes the general concepts of the bytecode file
79format without getting into specific layout details. It is recommended
80that you read this section thoroughly before interpreting the detailed
81descriptions.</p>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]82</div>
83<!-- _______________________________________________________________________ -->
84<div class="doc_subsection"><a name="blocks">Blocks</a> </div>
85<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]86<p>LLVM bytecode files consist simply of a sequence of blocks of bytes
87using a binary encoding Each block begins with an header of two
88unsigned integers. The first value identifies the type of block and the
89second value provides the size of the block in bytes. The block
90identifier is used because it is possible for entire blocks to be
91omitted from the file if they are empty. The block identifier helps the
92reader determine which kind of block is next in the file. Note that
93blocks can be nested within other blocks.</p>
94<p> All blocks are variable length, and the block header specifies the
95size of the block. All blocks begin on a byte index that is aligned to
96an even 32-bit boundary. That is, the first block is 32-bit aligned
97because it starts at offset 0. Each block is padded with zero fill
98bytes to ensure that the next block also starts on a 32-bit boundary.</p>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]99</div>
100<!-- _______________________________________________________________________ -->
101<div class="doc_subsection"><a name="lists">Lists</a> </div>
102<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]103<p>LLVM Bytecode blocks often contain lists of things of a similar
104type. For example, a function contains a list of instructions and a
105function type contains a list of argument types. There are two basic
106types of lists: length lists (<a href="#llist">llist</a>), and null
107terminated lists (<a href="#zlist">zlist</a>), as described below in
108the <a href="#encoding">Encoding Primitives</a>.</p>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]109</div>
110<!-- _______________________________________________________________________ -->
111<div class="doc_subsection"><a name="fields">Fields</a> </div>
112<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]113<p>Fields are units of information that LLVM knows how to write atomically. Most
114fields have a uniform length or some kind of length indication built into their
115encoding. For example, a constant string (array of bytes) is written simply as
116the length followed by the characters. Although this is similar to a list,
117constant strings are treated atomically and are thus fields.</p>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]118<p>Fields use a condensed bit format specific to the type of information
119they must contain. As few bits as possible are written for each field. The
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]120sections that follow will provide the details on how these fields are
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]121written and how the bits are to be interpreted.</p>
122</div>
123<!-- _______________________________________________________________________ -->
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]124<div class="doc_subsection"><a name="align">Alignment</a> </div>
Reid Spencer7aa940d2004-05-25 15:47:57 +0000[diff] [blame]125<div class="doc_text">
Reid Spencer267660f2004-08-03 20:33:56 +0000[diff] [blame]126 <p>To support cross-platform differences, the bytecode file is aligned on
127 certain boundaries. This means that a small amount of padding (at most 3
128 bytes) will be added to ensure that the next entry is aligned to a 32-bit
129 boundary.</p>
Chris Lattner8dabb502004-05-25 17:44:58 +0000[diff] [blame]130</div>
Reid Spencer7aa940d2004-05-25 15:47:57 +0000[diff] [blame]131<!-- _______________________________________________________________________ -->
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]132<div class="doc_subsection"><a name="vbr">Variable Bit-Rate Encoding</a>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]133</div>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]134<div class="doc_text">
135<p>Most of the values written to LLVM bytecode files are small integers. To
136minimize the number of bytes written for these quantities, an encoding scheme
137similar to UTF-8 is used to write integer data. The scheme is known as
138variable bit rate (vbr) encoding. In this encoding, the high bit of
139each byte is used to indicate if more bytes follow. If (byte &amp;
1400x80) is non-zero in any given byte, it means there is another byte
141immediately following that also contributes to the value. For the final
142byte (byte &amp; 0x80) is false (the high bit is not set). In each byte
143only the low seven bits contribute to the value. Consequently 32-bit
144quantities can take from one to <em>five</em> bytes to encode. In
145general, smaller quantities will encode in fewer bytes, as follows:</p>
146<table>
147 <tbody>
148 <tr>
149 <th>Byte #</th>
150 <th>Significant Bits</th>
151 <th>Maximum Value</th>
152 </tr>
153 <tr>
154 <td>1</td>
155 <td>0-6</td>
156 <td>127</td>
157 </tr>
158 <tr>
159 <td>2</td>
160 <td>7-13</td>
161 <td>16,383</td>
162 </tr>
163 <tr>
164 <td>3</td>
165 <td>14-20</td>
166 <td>2,097,151</td>
167 </tr>
168 <tr>
169 <td>4</td>
170 <td>21-27</td>
171 <td>268,435,455</td>
172 </tr>
173 <tr>
174 <td>5</td>
175 <td>28-34</td>
176 <td>34,359,738,367</td>
177 </tr>
178 <tr>
179 <td>6</td>
180 <td>35-41</td>
181 <td>4,398,046,511,103</td>
182 </tr>
183 <tr>
184 <td>7</td>
185 <td>42-48</td>
186 <td>562,949,953,421,311</td>
187 </tr>
188 <tr>
189 <td>8</td>
190 <td>49-55</td>
191 <td>72,057,594,037,927,935</td>
192 </tr>
193 <tr>
194 <td>9</td>
195 <td>56-62</td>
196 <td>9,223,372,036,854,775,807</td>
197 </tr>
198 <tr>
199 <td>10</td>
200 <td>63-69</td>
201 <td>1,180,591,620,717,411,303,423</td>
202 </tr>
203 </tbody>
204</table>
205<p>Note that in practice, the tenth byte could only encode bit 63 since
206the maximum quantity to use this encoding is a 64-bit integer.</p>
207<p><em>Signed</em> VBR values are encoded with the standard vbr
208encoding, but with the sign bit as the low order bit instead of the
209high order bit. This allows small negative quantities to be encoded
210efficiently. For example, -3
211is encoded as "((3 &lt;&lt; 1) | 1)" and 3 is encoded as "(3 &lt;&lt;
2121) | 0)", emitted with the standard vbr encoding above.</p>
213</div>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]214<!-- _______________________________________________________________________ -->
215<div class="doc_subsection"><a name="encoding">Encoding Primitives</a> </div>
216<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]217<p>Each field in the bytecode format is encoded into the file using a
218small set of primitive formats. The table below defines the encoding
219rules for the various primitives used and gives them each a type name.
220The type names used in the descriptions of blocks and fields in the <a
221 href="#details">Detailed Layout</a>next section. Any type name with
222the suffix <em>_vbr</em> indicates a quantity that is encoded using
223variable bit rate encoding as described above.</p>
224<table class="doc_table">
225 <tbody>
226 <tr>
227 <th><b>Type</b></th>
228 <th class="td_left"><b>Rule</b></th>
229 </tr>
230 <tr>
231 <td><a name="unsigned"><b>unsigned</b></a></td>
232 <td class="td_left">A 32-bit unsigned integer that always occupies four
Reid Spencerb39021b2004-05-23 17:05:09 +0000[diff] [blame]233 consecutive bytes. The unsigned integer is encoded using LSB first
234 ordering. That is bits 2<sup>0</sup> through 2<sup>7</sup> are in the
235 byte with the lowest file offset (little endian).</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]236 </tr>
237 <tr>
Reid Spencer301fe482004-08-03 20:57:56 +0000[diff] [blame]238 <td style="vertical-align: top;"><a name="uint24_vbr">
239 <b>uint24_vbr</b></a></td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]240 <td style="vertical-align: top; text-align: left;">A 24-bit unsigned
241 integer that occupies from one to four bytes using variable bit rate
242 encoding.</td>
243 </tr>
244 <tr>
245 <td><a name="uint32_vbr"><b>uint32_vbr</b></a></td>
Reid Spencerf08561f2004-08-03 19:20:18 +0000[diff] [blame]246 <td class="td_left">A 32-bit unsigned integer that occupies from one to
247 five bytes using variable bit rate encoding.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]248 </tr>
249 <tr>
250 <td><a name="uint64_vbr"><b>uint64_vbr</b></a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]251 <td class="td_left">A 64-bit unsigned integer that occupies from one to
252 ten bytes using variable bit rate encoding.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]253 </tr>
254 <tr>
255 <td><a name="int64_vbr"><b>int64_vbr</b></a></td>
Reid Spencerf08561f2004-08-03 19:20:18 +0000[diff] [blame]256 <td class="td_left">A 64-bit signed integer that occupies from one to ten
257 bytes using the signed variable bit rate encoding.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]258 </tr>
259 <tr>
260 <td><a name="char"><b>char</b></a></td>
Reid Spencerf08561f2004-08-03 19:20:18 +0000[diff] [blame]261 <td class="td_left">A single unsigned character encoded into one byte</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]262 </tr>
263 <tr>
264 <td><a name="bit"><b>bit(n-m)</b></a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]265 <td class="td_left">A set of bit within some larger integer field. The
266 values of <code>n</code> and <code>m</code> specify the inclusive range
267 of bits that define the subfield. The value for <code>m</code> may be
268 omitted if its the same as <code>n</code>.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]269 </tr>
270 <tr>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]271 <td style="vertical-align: top;"><b><a name="float"><b>float</b></a></b>
272 </td>
273 <td style="vertical-align: top; text-align: left;">A floating point
274 value encoded as a 32-bit IEEE value written in little-endian form.<br>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]275 </td>
276 </tr>
277 <tr>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]278 <td style="vertical-align: top;"><b><b><a name="double"><b>double</b></a>
279 </b></b></td>
280 <td style="vertical-align: top; text-align: left;">A floating point value
281 encoded as a64-bit IEEE value written in little-endian form</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]282 </tr>
283 <tr>
284 <td><a name="string"><b>string</b></a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]285 <td class="td_left">A uint32_vbr indicating the type of the constant
286 string which also includes its length, immediately followed by the
287 characters of the string. There is no terminating null byte in the
288 string.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]289 </tr>
290 <tr>
291 <td><a name="data"><b>data</b></a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]292 <td class="td_left">An arbitrarily long segment of data to which no
293 interpretation is implied. This is used for constant initializers.<br>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]294 </td>
295 </tr>
296 <tr>
297 <td><a name="llist"><b>llist(x)</b></a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]298 <td class="td_left">A length list of x. This means the list is encoded
299 as an <a href="#uint32_vbr">uint32_vbr</a> providing the length of the
300 list, followed by a sequence of that many "x" items. This implies that
301 the reader should iterate the number of times provided by the length.
302 </td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]303 </tr>
304 <tr>
305 <td><a name="zlist"><b>zlist(x)</b></a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]306 <td class="td_left">A zero-terminated list of x. This means the list is
307 encoded as a sequence of an indeterminate number of "x" items, followed
308 by an <a href="#uint32_vbr">uint32_vbr</a> terminating value. This
309 implies that none of the "x" items can have a zero value (or else the
310 list terminates).</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]311 </tr>
312 <tr>
313 <td><a name="block"><b>block</b></a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]314 <td class="td_left">A block of data that is logically related. A block
315 is an unsigned 32-bit integer that encodes the type of the block in
316 the low 5 bits and the size of the block in the high 27 bits. The
317 length does not include the block header or any alignment bytes at the
318 end of the block. Blocks may compose other blocks. </td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]319 </tr>
320 </tbody>
Reid Spencerb39021b2004-05-23 17:05:09 +0000[diff] [blame]321</table>
322</div>
323<!-- _______________________________________________________________________ -->
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]324<div class="doc_subsection"><a name="notation">Field Notation</a> </div>
325<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]326<p>In the detailed block and field descriptions that follow, a regex
327like notation is used to describe optional and repeated fields. A very
328limited subset of regex is used to describe these, as given in the
329following table: </p>
330<table class="doc_table">
331 <tbody>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]332 <tr>
333 <th><b>Character</b></th>
334 <th class="td_left"><b>Meaning</b></th>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]335 </tr>
336 <tr>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]337 <td><b><code>?</code></b></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]338 <td class="td_left">The question mark indicates 0 or 1 occurrences of
339 the thing preceding it.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]340 </tr>
341 <tr>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]342 <td><b><code>*</code></b></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]343 <td class="td_left">The asterisk indicates 0 or more occurrences of the
344 thing preceding it.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]345 </tr>
346 <tr>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]347 <td><b><code>+</code></b></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]348 <td class="td_left">The plus sign indicates 1 or more occurrences of the
349 thing preceding it.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]350 </tr>
351 <tr>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]352 <td><b><code>()</code></b></td>
353 <td class="td_left">Parentheses are used for grouping.</td>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]354 </tr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]355 <tr>
356 <td><b><code>,</code></b></td>
357 <td class="td_left">The comma separates sequential fields.</td>
358 </tr>
359 </tbody>
360</table>
361<p>So, for example, consider the following specifications:</p>
362<div class="doc_code">
363<ol>
364 <li><code>string?</code></li>
365 <li><code>(uint32_vbr,uin32_vbr)+</code></li>
366 <li><code>(unsigned?,uint32_vbr)*</code></li>
367 <li><code>(llist(unsigned))?</code></li>
368</ol>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]369</div>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]370<p>with the following interpretations:</p>
371<ol>
372 <li>An optional string. Matches either nothing or a single string</li>
373 <li>One or more pairs of uint32_vbr.</li>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]374 <li>Zero or more occurrences of either an unsigned followed by a uint32_vbr
375 or just a uint32_vbr.</li>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]376 <li>An optional length list of unsigned values.</li>
377</ol>
378</div>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]379<!-- _______________________________________________________________________ -->
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]380<div class="doc_subsection"><a name="slots">Slots</a> </div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]381<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]382<p>The bytecode format uses the notion of a "slot" to reference Types
383and Values. Since the bytecode file is a <em>direct</em> representation of
384LLVM's intermediate representation, there is a need to represent pointers in
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]385the file. Slots are used for this purpose. For example, if one has the
386following assembly:
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]387</p>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]388<div class="doc_code"><code> %MyType = type { int, sbyte }<br>
389%MyVar = external global %MyType
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]390</code></div>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]391<p>there are two definitions. The definition of <tt>%MyVar</tt> uses
392<tt>%MyType</tt>.
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]393In the C++ IR this linkage between <tt>%MyVar</tt> and <tt>%MyType</tt>
394is explicit through the use of C++ pointers. In bytecode, however, there's no
395ability to store memory addresses. Instead, we compute and write out
396slot numbers for every Type and Value written to the file.</p>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]397<p>A slot number is simply an unsigned 32-bit integer encoded in the variable
398bit rate scheme (see <a href="#encoding">encoding</a>). This ensures that
399low slot numbers are encoded in one byte. Through various bits of magic LLVM
400attempts to always keep the slot numbers low. The first attempt is to associate
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]401slot numbers with their "type plane". That is, Values of the same type
402are written to the bytecode file in a list (sequentially). Their order in
403that list determines their slot number. This means that slot #1 doesn't mean
404anything unless you also specify for which type you want slot #1. Types are
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]405always written to the file first (in the <a href="#globaltypes">Global Type
406Pool</a>) and in such a way that both forward and backward references of the
407types can often be resolved with a single pass through the type pool. </p>
Reid Spencerc4a8d392007-01-31 00:26:08 +0000[diff] [blame]408<p>In summary then, a slot number can be thought of as just a vbr encoded index
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]409into a list of Type* or Value*. To keep slot numbers low, Value* are indexed by
410two slot numbers: the "type plane index" (type slot) and the "value index"
411(value slot).</p>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]412</div>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]413<!-- *********************************************************************** -->
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]414<div class="doc_section"> <a name="general">General Structure</a> </div>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]415<!-- *********************************************************************** -->
416<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]417<p>This section provides the general structure of the LLVM bytecode
418file format. The bytecode file format requires blocks to be in a
419certain order and nested in a particular way so that an LLVM module can
420be constructed efficiently from the contents of the file. This ordering
421defines a general structure for bytecode files as shown below. The
422table below shows the order in which all block types may appear. Please
423note that some of the blocks are optional and some may be repeated. The
424structure is fairly loose because optional blocks, if empty, are
425completely omitted from the file.</p>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]426<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]427 <tbody>
428 <tr>
429 <th>ID</th>
430 <th>Parent</th>
431 <th>Optional?</th>
432 <th>Repeated?</th>
433 <th>Level</th>
434 <th>Block Type</th>
435 <th>Description</th>
436 </tr>
437 <tr>
438 <td>N/A</td>
439 <td>File</td>
440 <td>No</td>
441 <td>No</td>
442 <td>0</td>
443 <td class="td_left"><a href="#signature">Signature</a></td>
444 <td class="td_left">This contains the file signature (magic
445number) that identifies the file as LLVM bytecode.</td>
446 </tr>
447 <tr>
448 <td>0x01</td>
449 <td>File</td>
450 <td>No</td>
451 <td>No</td>
452 <td>0</td>
453 <td class="td_left"><a href="#module">Module</a></td>
454 <td class="td_left">This is the top level block in a bytecode
455file. It contains all the other blocks. </td>
456 </tr>
457 <tr>
458 <td>0x06</td>
459 <td>Module</td>
460 <td>No</td>
461 <td>No</td>
462 <td>1</td>
463 <td class="td_left">&nbsp;&nbsp;&nbsp;<a href="#globaltypes">Global&nbsp;Type&nbsp;Pool</a></td>
464 <td class="td_left">This block contains all the global (module)
465level types.</td>
466 </tr>
467 <tr>
468 <td>0x05</td>
469 <td>Module</td>
470 <td>No</td>
471 <td>No</td>
472 <td>1</td>
473 <td class="td_left">&nbsp;&nbsp;&nbsp;<a href="#globalinfo">Module&nbsp;Globals&nbsp;Info</a></td>
474 <td class="td_left">This block contains the type, constness, and
475linkage for each of the global variables in the module. It also
476contains the type of the functions and the constant initializers.</td>
477 </tr>
478 <tr>
479 <td>0x03</td>
480 <td>Module</td>
481 <td>Yes</td>
482 <td>No</td>
483 <td>1</td>
484 <td class="td_left">&nbsp;&nbsp;&nbsp;<a href="#constantpool">Module&nbsp;Constant&nbsp;Pool</a></td>
485 <td class="td_left">This block contains all the global constants
486except function arguments, global values and constant strings.</td>
487 </tr>
488 <tr>
489 <td>0x02</td>
490 <td>Module</td>
491 <td>Yes</td>
492 <td>Yes</td>
493 <td>1</td>
494 <td class="td_left">&nbsp;&nbsp;&nbsp;<a href="#functiondefs">Function&nbsp;Definitions</a>*</td>
495 <td class="td_left">One function block is written for each
496function in the module. The function block contains the instructions,
Reid Spencerc4a8d392007-01-31 00:26:08 +0000[diff] [blame]497type constant pool, and symbol table for the function.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]498 </tr>
499 <tr>
500 <td>0x03</td>
501 <td>Function</td>
502 <td>Yes</td>
503 <td>No</td>
504 <td>2</td>
505 <td class="td_left">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<a
506 href="#constantpool">Function&nbsp;Constant&nbsp;Pool</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]507 <td class="td_left">Any constants (including types) used solely within
508 the function are emitted here in the function constant pool. </td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]509 </tr>
510 <tr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]511 <td>0x07</td>
512 <td>Function</td>
513 <td>No</td>
514 <td>No</td>
515 <td>2</td>
516 <td class="td_left">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<a
517 href="#instructionlist">Instruction&nbsp;List</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]518 <td class="td_left">This block contains all the instructions of the
519 function. The basic blocks are inferred by terminating instructions.
520 </td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]521 </tr>
522 <tr>
523 <td>0x04</td>
524 <td>Function</td>
525 <td>Yes</td>
526 <td>No</td>
527 <td>2</td>
528 <td class="td_left">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<a
529 href="#symtab">Function&nbsp;Symbol&nbsp;Table</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]530 <td class="td_left">This symbol table provides the names for the function
531 specific values used (basic block labels mostly).</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]532 </tr>
533 <tr>
534 <td>0x04</td>
535 <td>Module</td>
536 <td>Yes</td>
537 <td>No</td>
538 <td>1</td>
539 <td class="td_left">&nbsp;&nbsp;&nbsp;<a href="#symtab">Module&nbsp;Symbol&nbsp;Table</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]540 <td class="td_left">This symbol table provides the names for the various
541 entries in the file that are not function specific (global vars, and
542 functions mostly).</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]543 </tr>
544 </tbody>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]545</table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]546<p>Use the links in the table for details about the contents of each of
547the block types.</p>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]548</div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]549<!-- *********************************************************************** -->
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]550<div class="doc_section"> <a name="blockdefs">Block Definitions</a> </div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]551<!-- *********************************************************************** -->
552<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]553<p>This section provides the detailed layout of the individual block
554types in the LLVM bytecode file format. </p>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]555</div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]556<!-- _______________________________________________________________________ -->
Reid Spencerb39021b2004-05-23 17:05:09 +0000[diff] [blame]557<div class="doc_subsection"><a name="signature">Signature Block</a> </div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]558<div class="doc_text">
Chris Lattner2b905652004-05-24 05:35:17 +0000[diff] [blame]559<p>The signature occurs in every LLVM bytecode file and is always first.
Reid Spencerb39021b2004-05-23 17:05:09 +0000[diff] [blame]560It simply provides a few bytes of data to identify the file as being an LLVM
561bytecode file. This block is always four bytes in length and differs from the
562other blocks because there is no identifier and no block length at the start
563of the block. Essentially, this block is just the "magic number" for the file.
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]564</p>
Reid Spencerda794e72004-11-08 08:55:21 +0000[diff] [blame]565<p>There are two types of signatures for LLVM bytecode: uncompressed and
566compressed as shown in the table below. </p>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]567<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]568 <tbody>
569 <tr>
570 <th><b>Type</b></th>
Reid Spencerda794e72004-11-08 08:55:21 +0000[diff] [blame]571 <th class="td_left"><b>Uncompressed</b></th>
572 <th class="td_left"><b>Compressed</b></th>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]573 </tr>
574 <tr>
575 <td><a href="#char">char</a></td>
576 <td class="td_left">Constant "l" (0x6C)</td>
Reid Spencerda794e72004-11-08 08:55:21 +0000[diff] [blame]577 <td class="td_left">Constant "l" (0x6C)</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]578 </tr>
579 <tr>
580 <td><a href="#char">char</a></td>
581 <td class="td_left">Constant "l" (0x6C)</td>
Reid Spencerda794e72004-11-08 08:55:21 +0000[diff] [blame]582 <td class="td_left">Constant "l" (0x6C)</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]583 </tr>
584 <tr>
585 <td><a href="#char">char</a></td>
586 <td class="td_left">Constant "v" (0x76)</td>
Reid Spencerda794e72004-11-08 08:55:21 +0000[diff] [blame]587 <td class="td_left">Constant "v" (0x76)</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]588 </tr>
589 <tr>
590 <td><a href="#char">char</a></td>
591 <td class="td_left">Constant "m" (0x6D)</td>
Reid Spencerda794e72004-11-08 08:55:21 +0000[diff] [blame]592 <td class="td_left">Constant "c" (0x63)</td>
593 </tr>
594 <tr>
595 <td><a href="#char">char</a></td>
596 <td class="td_left">N/A</td>
597 <td class="td_left">'0'=null,'1'=gzip,'2'=bzip2</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]598 </tr>
599 </tbody>
Reid Spencerb39021b2004-05-23 17:05:09 +0000[diff] [blame]600</table>
Reid Spencerda794e72004-11-08 08:55:21 +0000[diff] [blame]601<p>In other words, the uncompressed signature is just the characters 'llvm'
602while the compressed signature is the characters 'llvc' followed by an ascii
603digit ('0', '1', or '2') that indicates the kind of compression used. A value of
604'0' indicates that null compression was used. This can happen when compression
605was requested on a platform that wasn't configured for gzip or bzip2. A value of
606'1' means that the rest of the file is compressed using the gzip algorithm and
607should be uncompressed before interpretation. A value of '2' means that the rest
608of the file is compressed using the bzip2 algorithm and should be uncompressed
609before interpretation. In all cases, the data resulting from uncompression
610should be interpreted as if it occurred immediately after the 'llvm'
611signature (i.e. the uncompressed data begins with the
612<a href="#module">Module Block</a></p>
613<p><b>NOTE:</b> As of LLVM 1.4, all bytecode files produced by the LLVM tools
Reid Spencera4213b22004-11-08 09:10:50 +0000[diff] [blame]614are compressed by default. To disable compression, pass the
Reid Spencerda794e72004-11-08 08:55:21 +0000[diff] [blame]615<tt>--disable-compression</tt> option to the tool, if it supports it.
Reid Spencerb39021b2004-05-23 17:05:09 +0000[diff] [blame]616</div>
617<!-- _______________________________________________________________________ -->
618<div class="doc_subsection"><a name="module">Module Block</a> </div>
619<div class="doc_text">
620<p>The module block contains a small pre-amble and all the other blocks in
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]621the file. The table below shows the structure of the module block. Note that it
622only provides the module identifier, size of the module block, and the format
623information. Everything else is contained in other blocks, described in other
624sections.</p>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]625<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]626 <tbody>
627 <tr>
628 <th><b>Type</b></th>
629 <th class="td_left"><b>Field Description</b></th>
630 </tr>
631 <tr>
Reid Spencer5bc74d52004-08-16 19:24:36 +0000[diff] [blame]632 <td><a href="#unsigned">unsigned</a><br></td>
633 <td class="td_left"><a href="#mod_header">Module Block Identifier
634 (0x01)</a></td>
635 </tr>
636 <tr>
637 <td><a href="#unsigned">unsigned</a></td>
638 <td class="td_left"><a href="#mod_header">Module Block Size</a></td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]639 </tr>
640 <tr>
641 <td><a href="#uint32_vbr">uint32_vbr</a></td>
642 <td class="td_left"><a href="#format">Format Information</a></td>
643 </tr>
644 <tr>
645 <td><a href="#block">block</a></td>
646 <td class="td_left"><a href="#globaltypes">Global Type Pool</a></td>
647 </tr>
648 <tr>
649 <td><a href="#block">block</a></td>
650 <td class="td_left"><a href="#globalinfo">Module Globals Info</a></td>
651 </tr>
652 <tr>
653 <td><a href="#block">block</a></td>
654 <td class="td_left"><a href="#constantpool">Module Constant Pool</a></td>
655 </tr>
656 <tr>
657 <td><a href="#block">block</a>*</td>
658 <td class="td_left"><a href="#functiondefs">Function Definitions</a></td>
659 </tr>
660 <tr>
661 <td><a href="#block">block</a></td>
Reid Spencer8996e552004-08-17 00:49:03 +0000[diff] [blame]662 <td class="td_left"><a href="#symtab">Module Symbol Table</a></td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]663 </tr>
664 </tbody>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]665</table>
666</div>
Reid Spencer5bc74d52004-08-16 19:24:36 +0000[diff] [blame]667
668<!-- _______________________________________________________________________ -->
669<div class="doc_subsubsection"><a name="mod_header">Module Block Header</a></div>
670<div class="doc_text">
671 <p>The block header for the module block uses a longer format than the other
672 blocks in a bytecode file. Specifically, instead of encoding the type and size
673 of the block into a 32-bit integer with 5-bits for type and 27-bits for size,
674 the module block header uses two 32-bit unsigned values, one for type, and one
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]675 for size. While the 2<sup>27</sup> byte limit on block size is sufficient
676 for the blocks contained in the module, it isn't sufficient for the module
677 block itself because we want to ensure that bytecode files as large as
678 2<sup>32</sup> bytes are possible. For this reason, the module block (and
679 only the module block) uses a long format header.</p>
Reid Spencer5bc74d52004-08-16 19:24:36 +0000[diff] [blame]680</div>
681
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]682<!-- _______________________________________________________________________ -->
683<div class="doc_subsubsection"><a name="format">Format Information</a></div>
684<div class="doc_text">
Owen Andersond753fbc2007-01-27 19:23:25 +0000[diff] [blame]685<p>The format information field is encoded into a <a href="#uint32_vbr">uint32_vbr</a>.</p>
686
687<p>Of particular note, the bytecode format number is simply a 32-bit
John Criswell611a8d12005-10-24 16:20:10 +0000[diff] [blame]688monotonically increasing integer that identifies the version of the bytecode
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]689format (which is not directly related to the LLVM release number). The
690bytecode versions defined so far are (note that this document only
Owen Andersond753fbc2007-01-27 19:23:25 +0000[diff] [blame]691describes the latest version, 2.0):</p>
Chris Lattner2b905652004-05-24 05:35:17 +0000[diff] [blame]692<ul>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]693 <li>#0: LLVM 1.0 &amp; 1.1</li>
694 <li>#1: LLVM 1.2</li>
695 <li>#2: LLVM 1.2.5 (not released)</li>
John Criswell1d9be9e2005-10-24 17:10:57 +0000[diff] [blame]696 <li>#3: LLVM 1.3</li>
697 <li>#4: LLVM 1.3.x (not released)</li>
Owen Andersond753fbc2007-01-27 19:23:25 +0000[diff] [blame]698 <li>#5: LLVM 1.4 through 1.8</li>
699 <li>#6: LLVM 1.9</li>
700 <li>#7: LLVM 2.0 and newer</li>
Chris Lattner2b905652004-05-24 05:35:17 +0000[diff] [blame]701</ul>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]702</div>
703<!-- _______________________________________________________________________ -->
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]704<div class="doc_subsection"><a name="globaltypes">Global Type Pool</a> </div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]705<div class="doc_text">
Chris Lattner2b905652004-05-24 05:35:17 +0000[diff] [blame]706<p>The global type pool consists of type definitions. Their order of appearance
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]707in the file determines their type slot number (0 based). Slot numbers are
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]708used to replace pointers in the intermediate representation. Each slot number
709uniquely identifies one entry in a type plane (a collection of values of the
710same type). Since all values have types and are associated with the order in
711which the type pool is written, the global type pool <em>must</em> be written
712as the first block of a module. If it is not, attempts to read the file will
713fail because both forward and backward type resolution will not be possible.</p>
714<p>The type pool is simply a list of type definitions, as shown in the
715table below.</p>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]716<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]717 <tbody>
718 <tr>
719 <th><b>Type</b></th>
720 <th class="td_left"><b>Field Description</b></th>
721 </tr>
722 <tr>
723 <td><a href="#unsigned">block</a></td>
724 <td class="td_left">Type Pool Identifier (0x06) + Size<br>
725 </td>
726 </tr>
727 <tr>
728 <td><a href="#llist">llist</a>(<a href="#type">type</a>)</td>
729 <td class="td_left">A length list of type definitions.</td>
730 </tr>
731 </tbody>
Reid Spencerb39021b2004-05-23 17:05:09 +0000[diff] [blame]732</table>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]733</div>
734<!-- _______________________________________________________________________ -->
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]735<div class="doc_subsubsection"><a name="type">Type Definitions</a></div>
736<div class="doc_text">
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]737<p>Types in the type pool are defined using a different format for each kind
738of type, as given in the following sections.</p>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]739<h3>Primitive Types</h3>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]740<p>The primitive types encompass the basic integer and floating point
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]741types. They are encoded simply as their TypeID.</p>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]742<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]743 <tbody>
744 <tr>
745 <th><b>Type</b></th>
746 <th class="td_left"><b>Description</b></th>
747 </tr>
748 <tr>
749 <td><a href="#uint24_vbr">uint24_vbr</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]750 <td class="td_left">Type ID for the primitive types (values 1 to 11)
751 <sup>1</sup></td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]752 </tr>
753 </tbody>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]754</table>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]755Notes:
756<ol>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]757 <li>The values for the Type IDs for the primitive types are provided by the
758 definition of the <code>llvm::Type::TypeID</code> enumeration in
759 <code>include/llvm/Type.h</code>. The enumeration gives the following mapping:
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]760 <ol>
761 <li>bool</li>
762 <li>ubyte</li>
763 <li>sbyte</li>
764 <li>ushort</li>
765 <li>short</li>
766 <li>uint</li>
767 <li>int</li>
768 <li>ulong</li>
769 <li>long</li>
770 <li>float</li>
771 <li>double</li>
772 </ol>
773 </li>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]774</ol>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]775<h3>Function Types</h3>
776<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]777 <tbody>
778 <tr>
779 <th><b>Type</b></th>
780 <th class="td_left"><b>Description</b></th>
781 </tr>
782 <tr>
783 <td><a href="#uint24_vbr">uint24_vbr</a></td>
784 <td class="td_left">Type ID for function types (13)</td>
785 </tr>
786 <tr>
787 <td><a href="#uint24_vbr">uint24_vbr</a></td>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]788 <td class="td_left">Type slot number of function's return type.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]789 </tr>
790 <tr>
791 <td><a href="#llist">llist</a>(<a href="#uint24_vbr">uint24_vbr</a>)</td>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]792 <td class="td_left">Type slot number of each argument's type.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]793 </tr>
794 <tr>
795 <td><a href="#uint32_vbr">uint32_vbr</a>?</td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]796 <td class="td_left">Value 0 if this is a varargs function, missing
797 otherwise.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]798 </tr>
799 </tbody>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]800</table>
801<h3>Structure Types</h3>
802<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]803 <tbody>
804 <tr>
805 <th><b>Type</b></th>
806 <th class="td_left"><b>Description</b></th>
807 </tr>
808 <tr>
809 <td><a href="#uint24_vbr">uint24_vbr</a></td>
810 <td class="td_left">Type ID for structure types (14)</td>
811 </tr>
812 <tr>
813 <td><a href="#zlist">zlist</a>(<a href="#uint24_vbr">uint24_vbr</a>)</td>
814 <td class="td_left">Slot number of each of the element's fields.</td>
815 </tr>
816 </tbody>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]817</table>
818<h3>Array Types</h3>
819<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]820 <tbody>
821 <tr>
822 <th><b>Type</b></th>
823 <th class="td_left"><b>Description</b></th>
824 </tr>
825 <tr>
826 <td><a href="#uint24_vbr">uint24_vbr</a></td>
827 <td class="td_left">Type ID for Array Types (15)</td>
828 </tr>
829 <tr>
830 <td><a href="#uint24_vbr">uint24_vbr</a></td>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]831 <td class="td_left">Type slot number of array's element type.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]832 </tr>
833 <tr>
834 <td><a href="#uint32_vbr">uint32_vbr</a></td>
835 <td class="td_left">The number of elements in the array.</td>
836 </tr>
837 </tbody>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]838</table>
839<h3>Pointer Types</h3>
840<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]841 <tbody>
842 <tr>
843 <th><b>Type</b></th>
844 <th class="td_left"><b>Description</b></th>
845 </tr>
846 <tr>
847 <td><a href="#uint24_vbr">uint24_vbr</a></td>
848 <td class="td_left">Type ID For Pointer Types (16)</td>
849 </tr>
850 <tr>
851 <td><a href="#uint24_vbr">uint24_vbr</a></td>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]852 <td class="td_left">Type slot number of pointer's element type.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]853 </tr>
854 </tbody>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]855</table>
856<h3>Opaque Types</h3>
857<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]858 <tbody>
859 <tr>
860 <th><b>Type</b></th>
861 <th class="td_left"><b>Description</b></th>
862 </tr>
863 <tr>
864 <td><a href="#uint24_vbr">uint24_vbr</a></td>
865 <td class="td_left">Type ID For Opaque Types (17)</td>
866 </tr>
867 </tbody>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]868</table>
Brian Gaeke715c90b2004-08-20 06:00:58 +0000[diff] [blame]869<h3>Packed Types</h3>
870<table>
871 <tbody>
872 <tr>
873 <th><b>Type</b></th>
874 <th class="td_left"><b>Description</b></th>
875 </tr>
876 <tr>
877 <td><a href="#uint24_vbr">uint24_vbr</a></td>
878 <td class="td_left">Type ID for Packed Types (18)</td>
879 </tr>
880 <tr>
881 <td><a href="#uint24_vbr">uint24_vbr</a></td>
882 <td class="td_left">Slot number of packed vector's element type.</td>
883 </tr>
884 <tr>
885 <td><a href="#uint32_vbr">uint32_vbr</a></td>
886 <td class="td_left">The number of elements in the packed vector.</td>
887 </tr>
888 </tbody>
889</table>
Andrew Lenharth88942552006-12-08 17:50:05 +0000[diff] [blame]890<h3>Packed Structure Types</h3>
891<table>
892 <tbody>
893 <tr>
894 <th><b>Type</b></th>
895 <th class="td_left"><b>Description</b></th>
896 </tr>
897 <tr>
898 <td><a href="#uint24_vbr">uint24_vbr</a></td>
899 <td class="td_left">Type ID for packed structure types (19)</td>
900 </tr>
901 <tr>
902 <td><a href="#zlist">zlist</a>(<a href="#uint24_vbr">uint24_vbr</a>)</td>
903 <td class="td_left">Slot number of each of the element's fields.</td>
904 </tr>
905 </tbody>
906</table>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]907</div>
908<!-- _______________________________________________________________________ -->
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]909<div class="doc_subsection"><a name="globalinfo">Module Global Info</a>
910</div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]911<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]912<p>The module global info block contains the definitions of all global
913variables including their initializers and the <em>declaration</em> of
914all functions. The format is shown in the table below:</p>
915<table>
916 <tbody>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]917 <tr>
918 <th><b>Type</b></th>
919 <th class="td_left"><b>Field Description</b></th>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]920 </tr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]921 <tr>
922 <td><a href="#block">block</a></td>
Chris Lattner45f50512006-01-23 23:38:09 +0000[diff] [blame]923 <td class="td_left">Module global info identifier (0x05) + size</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]924 </tr>
925 <tr>
926 <td><a href="#zlist">zlist</a>(<a href="#globalvar">globalvar</a>)</td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]927 <td class="td_left">A zero terminated list of global var definitions
928 occurring in the module.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]929 </tr>
930 <tr>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]931 <td><a href="#zlist">zlist</a>(<a href="#funcfield">funcfield</a>)</td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]932 <td class="td_left">A zero terminated list of function definitions
933 occurring in the module.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]934 </tr>
935 <tr>
Chris Lattner45f50512006-01-23 23:38:09 +0000[diff] [blame]936 <td><a href="#llist">llist</a>(<a href="#string">string</a>)</td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]937 <td class="td_left">A length list of strings that specify the names of
938 the libraries that this module depends upon.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]939 </tr>
940 <tr>
Chris Lattner45f50512006-01-23 23:38:09 +0000[diff] [blame]941 <td><a href="#string">string</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]942 <td class="td_left">The target triple for the module (blank means no
943 target triple specified, i.e. a platform-independent module).</td>
Owen Andersond753fbc2007-01-27 19:23:25 +0000[diff] [blame]944 </tr>
945 <tr>
946 <td><a href="#string">string</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]947 <td class="td_left">The data layout string describing the endianness,
948 pointer size, and type alignments for which the module was written
949 (blank means no data layout specified, i.e. a platform-independent
950 module).</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]951 </tr>
Chris Lattner767d6ba2005-11-12 01:46:21 +0000[diff] [blame]952 <tr>
Chris Lattner45f50512006-01-23 23:38:09 +0000[diff] [blame]953 <td><a href="#llist">llist</a>(<a href="#string">string</a>)</td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]954 <td class="td_left">A length list of strings that defines a table of
955 section strings for globals. A global's SectionID is an index into
956 this table.</td>
Chris Lattner45f50512006-01-23 23:38:09 +0000[diff] [blame]957 </tr>
958 <tr>
959 <td><a href="#string">string</a></td>
960 <td class="td_left">The inline asm block for this module.</td>
Chris Lattner767d6ba2005-11-12 01:46:21 +0000[diff] [blame]961 </tr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]962 </tbody>
963</table>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]964</div>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]965
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]966<!-- _______________________________________________________________________ -->
967<div class="doc_subsubsection"><a name="globalvar">Global Variable Field</a>
968</div>
Chris Lattnerafedcb32005-11-06 07:20:25 +0000[diff] [blame]969
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]970<div class="doc_text">
Chris Lattnerafedcb32005-11-06 07:20:25 +0000[diff] [blame]971
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]972<p>Global variables are written using an <a href="#uint32_vbr">uint32_vbr</a>
Chris Lattnerafedcb32005-11-06 07:20:25 +0000[diff] [blame]973that encodes information about the global variable, an optional extension vbr,
974and a an optional initializers for the global var.</p>
975
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]976<p>The table below provides the bit layout of the first <a
977 href="#uint32_vbr">uint32_vbr</a> that describes the global variable.</p>
Chris Lattnerafedcb32005-11-06 07:20:25 +0000[diff] [blame]978
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]979<table>
980 <tbody>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]981 <tr>
982 <th><b>Type</b></th>
983 <th class="td_left"><b>Description</b></th>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]984 </tr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]985 <tr>
986 <td><a href="#bit">bit(0)</a></td>
987 <td class="td_left">Is constant?</td>
988 </tr>
989 <tr>
990 <td><a href="#bit">bit(1)</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]991 <td class="td_left">Has initializer? Note that this bit determines
992 whether the constant initializer field (described below) follows.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]993 </tr>
994 <tr>
995 <td><a href="#bit">bit(2-4)</a></td>
996 <td class="td_left">Linkage type: 0=External, 1=Weak,
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]997 2=Appending, 3=Internal, 4=LinkOnce, 5=DllImport,
998 6=DllExport, 7=ExternWeak</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]999 </tr>
1000 <tr>
1001 <td><a href="#bit">bit(5-31)</a></td>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1002 <td class="td_left">Type slot number of type for the global variable.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1003 </tr>
1004 </tbody>
1005</table>
Chris Lattnerafedcb32005-11-06 07:20:25 +0000[diff] [blame]1006
1007<p>When the Linkage type is set to 3 (internal) and the initializer field is set
1008to 0 (an invalid combination), an extension word follows the first <a
1009href="#uint32_vbr">uint32_vbr</a> which encodes the real linkage and init flag,
1010and can includes more information:</p>
1011
1012<table>
1013 <tbody>
1014 <tr>
1015 <th><b>Type</b></th>
1016 <th class="td_left"><b>Description</b></th>
1017 </tr>
1018 <tr>
1019 <td><a href="#bit">bit(0)</a></td>
1020 <td class="td_left">Has initializer? Indicates the real value of the "Has
1021 initializer" field for the global. </td>
1022 </tr>
1023 <tr>
1024 <td><a href="#bit">bit(2-4)</a></td>
1025 <td class="td_left">Linkage type: Indicates the real value of the "linkage
1026 type" field for the global.</td>
1027 </tr>
1028 <tr>
1029 <td><a href="#bit">bit(4-8)</a></td>
1030 <td class="td_left">The log-base-2 of the alignment for the global.</td>
1031 </tr>
1032 <tr>
Chris Lattner767d6ba2005-11-12 01:46:21 +0000[diff] [blame]1033 <td><a href="#bit">bit(9)</a></td>
1034 <td class="td_left">If this bit is set, a SectionID follows this vbr.</td>
1035 </tr>
1036 <tr>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]1037 <td><a href="#bit">bit(10-12)</a></td>
1038 <td class="td_left">Visibility style: 0=Default, 1=Hidden.</td>
1039 </tr>
1040 <tr>
1041 <td><a href="#bit">bit(13-31)</a></td>
Chris Lattnerafedcb32005-11-06 07:20:25 +0000[diff] [blame]1042 <td class="td_left">Currently unassigned.</td>
1043 </tr>
1044 </tbody>
1045</table>
1046
Chris Lattner767d6ba2005-11-12 01:46:21 +0000[diff] [blame]1047<p>If the SectionID bit is set above, the following field is included:</p>
Chris Lattnerafedcb32005-11-06 07:20:25 +0000[diff] [blame]1048
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1049<table>
1050 <tbody>
1051 <tr>
1052 <th><b>Type</b></th>
1053 <th class="td_left"><b>Description</b></th>
1054 </tr>
1055 <tr>
Chris Lattner767d6ba2005-11-12 01:46:21 +0000[diff] [blame]1056 <td><a href="#uint32_vbr">uint32_vbr</a>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1057 </td>
Chris Lattner767d6ba2005-11-12 01:46:21 +0000[diff] [blame]1058 <td class="td_left">An optional section ID number, specifying the string
1059 to use for the section of the global. This an index (+1) of an entry
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1060 into the SectionID llist in the
1061 <a href="#globalinfo">Module Global Info</a> block. If this value is
1062 0 or not present, the global has an empty section string.</td>
Chris Lattner767d6ba2005-11-12 01:46:21 +0000[diff] [blame]1063 </tr>
1064 </tbody>
1065</table>
1066
1067<p>If the "Has initializer" field is set, the following field is included:</p>
1068
1069<table>
1070 <tbody>
1071 <tr>
1072 <th><b>Type</b></th>
1073 <th class="td_left"><b>Description</b></th>
1074 </tr>
1075 <tr>
1076 <td><a href="#uint32_vbr">uint32_vbr</a>
1077 </td>
1078 <td class="td_left">An optional value slot number for the global
1079 variable's constant initializer.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1080 </tr>
1081 </tbody>
1082</table>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1083</div>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1084
1085<!-- _______________________________________________________________________ -->
1086<div class="doc_subsubsection"><a name="funcfield">Function Field</a>
1087</div>
1088<div class="doc_text">
1089<p>Functions are written using an <a href="#uint32_vbr">uint32_vbr</a>
Chris Lattnerafedcb32005-11-06 07:20:25 +0000[diff] [blame]1090that encodes information about the function and a set of flags. If needed,
1091an extension word may follow this first field.</p>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1092
1093<p>The table below provides the bit layout of the <a
1094href="#uint32_vbr">uint32_vbr</a> that describes the function.</p>
1095
1096<table>
1097 <tbody>
1098 <tr>
1099 <th><b>Type</b></th>
1100 <th class="td_left"><b>Description</b></th>
1101 </tr>
1102 <tr>
Chris Lattnerced62222004-11-15 22:54:50 +0000[diff] [blame]1103 <td><a href="#bit">bit(0-3)</a></td>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1104 <td class="td_left">
Chris Lattner52942b52005-11-06 07:48:11 +0000[diff] [blame]1105 Encodes the calling convention number of the function. The
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1106 CC number of the function is the value of this field minus one.
1107 </td>
Chris Lattnerced62222004-11-15 22:54:50 +0000[diff] [blame]1108 </tr>
1109 <tr>
1110 <td><a href="#bit">bit(4)</a></td>
1111 <td class="td_left">If this bit is set to 1, the indicated function is
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1112 external, and there is no
1113 <a href="#functiondefs">Function Definiton Block</a> in the bytecode
1114 file for the function. If the function is external and has
1115 <tt>dllimport or extern_weak</tt> linkage additional field in the
1116 extension word is used to indicate the actual linkage type.</td>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1117 </tr>
1118 <tr>
Chris Lattnerafedcb32005-11-06 07:20:25 +0000[diff] [blame]1119 <td><a href="#bit">bit(5-30)</a></td>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1120 <td class="td_left">Type slot number of type for the function.</td>
1121 </tr>
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]1122 <tr>
Chris Lattnerafedcb32005-11-06 07:20:25 +0000[diff] [blame]1123 <td><a href="#bit">bit(31)</a></td>
1124 <td class="td_left">Indicates whether an extension word follows.</td>
1125 </tr>
1126 </tbody>
1127</table>
1128
1129<p>If bit(31) is set, an additional <a href="#uint32_vbr">uint32_vbr</a> word
1130follows with the following fields:</p>
1131
1132<table>
1133 <tbody>
1134 <tr>
1135 <th><b>Type</b></th>
1136 <th class="td_left"><b>Description</b></th>
1137 </tr>
1138 <tr>
1139 <td><a href="#bit">bit(0-4)</a></td>
1140 <td class="td_left">The log-base-2 of the alignment for the function.</td>
1141 </tr>
1142 <tr>
Chris Lattner52942b52005-11-06 07:48:11 +0000[diff] [blame]1143 <td><a href="#bit">bit(5-9)</a></td>
1144 <td class="td_left">The top nibble of the calling convention.</td>
1145 </tr>
1146 <tr>
Chris Lattner767d6ba2005-11-12 01:46:21 +0000[diff] [blame]1147 <td><a href="#bit">bit(10)</a></td>
1148 <td class="td_left">If this bit is set, a SectionID follows this vbr.</td>
1149 </tr>
1150 <tr>
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]1151 <td><a href="#bit">bit(11-12)</a></td>
1152 <td class="td_left">Linkage type for external functions. 0 - External
1153 linkage, 1 - DLLImport linkage, 2 - External weak linkage.</td>
1154 </tr>
1155 <tr>
1156 <td><a href="#bit">bit(13-31)</a></td>
Chris Lattnerafedcb32005-11-06 07:20:25 +0000[diff] [blame]1157 <td class="td_left">Currently unassigned.</td>
1158 </tr>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1159 </tbody>
1160</table>
1161
Chris Lattner767d6ba2005-11-12 01:46:21 +0000[diff] [blame]1162<p>If the SectionID bit is set above, the following field is included:</p>
1163
1164<table>
1165 <tbody>
1166 <tr>
1167 <th><b>Type</b></th>
1168 <th class="td_left"><b>Description</b></th>
1169 </tr>
1170 <tr>
1171 <td><a href="#uint32_vbr">uint32_vbr</a>
1172 </td>
1173 <td class="td_left">An optional section ID number, specifying the string
1174 to use for the section of the function. This an index (+1) of an entry
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1175 into the SectionID llist in the
1176 <a href="#globalinfo">Module Global Info</a> block. If this value is
1177 0 or not present, the function has an empty section string.</td>
Chris Lattner767d6ba2005-11-12 01:46:21 +0000[diff] [blame]1178 </tr>
1179 </tbody>
1180</table>
1181
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1182</div>
1183
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]1184<!-- _______________________________________________________________________ -->
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]1185<div class="doc_subsection"><a name="constantpool">Constant Pool</a> </div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]1186<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1187<p>A constant pool defines as set of constant values. There are
1188actually two types of constant pool blocks: one for modules and one for
1189functions. For modules, the block begins with the constant strings
1190encountered anywhere in the module. For functions, the block begins
1191with types only encountered in the function. In both cases the header
1192is identical. The tables that follow, show the header, module constant
1193pool preamble, function constant pool preamble, and the part common to
1194both function and module constant pools.</p>
1195<p><b>Common Block Header</b></p>
1196<table>
1197 <tbody>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1198 <tr>
1199 <th><b>Type</b></th>
1200 <th class="td_left"><b>Field Description</b></th>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1201 </tr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1202 <tr>
1203 <td><a href="#block">block</a></td>
1204 <td class="td_left">Constant pool identifier (0x03) + size<br>
1205 </td>
1206 </tr>
1207 </tbody>
1208</table>
1209<p><b>Module Constant Pool Preamble (constant strings)</b></p>
1210<table>
1211 <tbody>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1212 <tr>
1213 <th><b>Type</b></th>
1214 <th class="td_left"><b>Field Description</b></th>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1215 </tr>
1216 <tr>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1217 <td><a href="#uint32_vbr">uint32_vbr</a></td>
1218 <td class="td_left">The number of constant strings that follow.</td>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1219 </tr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1220 <tr>
1221 <td><a href="#uint32_vbr">uint32_vbr</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1222 <td class="td_left">Zero. This identifies the following "plane" as
1223 containing the constant strings. This is needed to identify it uniquely
1224 from other constant planes that follow. </td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1225 </tr>
1226 <tr>
1227 <td><a href="#uint24_vbr">uint24_vbr</a>+</td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1228 <td class="td_left">Type slot number of the constant string's type. Note
1229 that the constant string's type implicitly defines the length of the
1230 string. </td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1231 </tr>
1232 </tbody>
1233</table>
1234<p><b>Function Constant Pool Preamble (function types)</b></p>
1235<p>The structure of the types for functions is identical to the <a
1236 href="#globaltypes">Global Type Pool</a>. Please refer to that section
1237for the details. </p>
1238<p><b>Common Part (other constants)</b></p>
1239<table>
1240 <tbody>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1241 <tr>
1242 <th><b>Type</b></th>
1243 <th class="td_left"><b>Field Description</b></th>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1244 </tr>
1245 <tr>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1246 <td><a href="#uint32_vbr">uint32_vbr</a></td>
1247 <td class="td_left">Number of entries in this type plane.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1248 </tr>
1249 <tr>
1250 <td><a href="#uint24_vbr">uint24_vbr</a></td>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1251 <td class="td_left">Type slot number of this plane.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1252 </tr>
1253 <tr>
Reid Spencer82c46712004-07-07 13:34:26 +0000[diff] [blame]1254 <td><a href="#constant">constant</a>+</td>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1255 <td class="td_left">The definition of a constant (see below).</td>
1256 </tr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1257 </tbody>
1258</table>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1259</div>
Chris Lattner591d0492006-01-25 23:31:53 +0000[diff] [blame]1260
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1261<!-- _______________________________________________________________________ -->
Chris Lattner591d0492006-01-25 23:31:53 +0000[diff] [blame]1262<div class="doc_subsubsection"><a name="constant">Simple Constant Pool
1263Entries</a></div>
1264
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1265<div class="doc_text">
Chris Lattner591d0492006-01-25 23:31:53 +0000[diff] [blame]1266
1267<p>Constant pool entries come in many shapes and flavors. The sections that
1268follow define the format for each of them. All constants start with a <a
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1269 href="#uint32_vbr">uint32_vbr</a> encoded integer that provides the
1270number of operands for the constant. For primitive, structure, and
Chris Lattner591d0492006-01-25 23:31:53 +0000[diff] [blame]1271array constants, this will always be zero to indicate that the form of the
1272constant is solely determined by its type. In this case, we have the following
1273field definitions, based on type:</p>
1274
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1275<ul>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1276 <li><b>Bool</b>. This is written as an <a href="#uint32_vbr">uint32_vbr</a> of
1277 value 1U or 0U.</li>
1278 <li><b>Signed Integers (sbyte,short,int,long)</b>. These are written as an
1279 <a href="#int64_vbr">int64_vbr</a> with the corresponding value.</li>
1280 <li><b>Unsigned Integers (ubyte,ushort,uint,ulong)</b>. These are written as
1281 an <a href="#uint64_vbr">uint64_vbr</a> with the corresponding value. </li>
1282 <li><b>Floating Point</b>. Both the float and double types are written
1283 literally in binary format.</li>
1284 <li><b>Arrays</b>. Arrays are written simply as a list of
1285 <a href="#uint32_vbr">uint32_vbr</a> encoded value slot numbers to the
1286 constant element values.</li>
1287 <li><b>Structures</b>. Structures are written simply as a list of
1288 <a href="#uint32_vbr">uint32_vbr</a> encoded value slot numbers to the
1289 constant field values of the structure.</li>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1290</ul>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1291
Chris Lattner591d0492006-01-25 23:31:53 +0000[diff] [blame]1292</div>
1293
1294<!-- _______________________________________________________________________ -->
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]1295<div class="doc_subsubsection">Undef Entries</div>
Chris Lattner591d0492006-01-25 23:31:53 +0000[diff] [blame]1296
1297<div class="doc_text">
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1298<p>When the number of operands to the constant is one, we have an 'undef' value
1299of the specified type.</p>
Chris Lattner591d0492006-01-25 23:31:53 +0000[diff] [blame]1300</div>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1301
Chris Lattner591d0492006-01-25 23:31:53 +0000[diff] [blame]1302<!-- _______________________________________________________________________ -->
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]1303<div class="doc_subsubsection">Inline Assembler Entries</div>
Chris Lattner591d0492006-01-25 23:31:53 +0000[diff] [blame]1304
1305<div class="doc_text">
1306<p>Inline Assembler entries are stored in the constant pool, though they are not
1307 officially LLVM constants. These entries are marked with a value of
1308 "4294967295" (all ones) for the number of operands. They are encoded as
1309 follows:</p>
1310
1311<table>
1312 <tbody>
1313 <tr>
1314 <th><b>Type</b></th>
1315 <th class="td_left"><b>Field Description</b></th>
1316 </tr>
1317 <tr>
1318 <td><a href="#string">string</a></td>
1319 <td class="td_left">The asm string.</td>
1320 </tr>
1321 <tr>
1322 <td><a href="#string">string</a></td>
1323 <td class="td_left">The constraints string.</td>
1324 </tr>
1325 <tr>
1326 <td><a href="#uint32_vbr">uint32_vbr</a></td>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]1327 <td class="td_left">Flags</td>
Chris Lattner591d0492006-01-25 23:31:53 +0000[diff] [blame]1328 </tr>
1329 </tbody>
1330</table>
1331
1332<p>Currently, the only defined flag, the low bit, indicates whether or not the
1333 inline assembler has side effects.</p>
1334
1335</div>
1336
1337<!-- _______________________________________________________________________ -->
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]1338<div class="doc_subsubsection">Constant Expression Entries</div>
Chris Lattner591d0492006-01-25 23:31:53 +0000[diff] [blame]1339
1340<div class="doc_text">
1341
1342<p>Otherwise, we have a constant expression. The format of the constant
1343expression is specified in the table below, and the number is equal to the
1344number of operands+1.</p>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1345<table>
1346 <tbody>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1347 <tr>
1348 <th><b>Type</b></th>
1349 <th class="td_left"><b>Field Description</b></th>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1350 </tr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1351 <tr>
1352 <td><a href="#uint32_vbr">uint32_vbr</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1353 <td class="td_left">Op code of the instruction for the constant
1354 expression.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1355 </tr>
1356 <tr>
1357 <td><a href="#uint32_vbr">uint32_vbr</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1358 <td class="td_left">The value slot number of the constant value for an
1359 operand.<sup>1</sup></td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1360 </tr>
1361 <tr>
1362 <td><a href="#uint24_vbr">uint24_vbr</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1363 <td class="td_left">The type slot number for the type of the constant
1364 value for an operand.<sup>1</sup></td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1365 </tr>
1366 </tbody>
1367</table>
1368Notes:
1369<ol>
1370 <li>Both these fields are repeatable but only in pairs.</li>
1371</ol>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]1372</div>
1373<!-- _______________________________________________________________________ -->
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1374<div class="doc_subsection"><a name="functiondefs">Function Definition</a></div>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]1375<div class="doc_text">
Reid Spencerc4a8d392007-01-31 00:26:08 +0000[diff] [blame]1376<p>Function definitions contain the linkage, constant pool, instruction list,
1377and symbol table for a function. The following table shows the structure of
1378a function definition.</p>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1379<table>
1380 <tbody>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1381 <tr>
1382 <th><b>Type</b></th>
1383 <th class="td_left"><b>Field Description</b></th>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1384 </tr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1385 <tr>
1386 <td><a href="#block">block</a><br>
1387 </td>
1388 <td class="td_left">Function definition block identifier (0x02) +
1389size<br>
1390 </td>
1391 </tr>
1392 <tr>
1393 <td><a href="#uint32_vbr">uint32_vbr</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1394 <td class="td_left">
1395 <a href="#funclinkage_and_visibility">The linkage and visibility</a>
1396 style field</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1397 </tr>
1398 <tr>
1399 <td><a href="#block">block</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1400 <td class="td_left">The <a href="#constantpool">constant pool</a> block
1401 for this function.<sup>2</sup></td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1402 </tr>
1403 <tr>
1404 <td><a href="#block">block</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1405 <td class="td_left">The <a href="#instructionlist">instruction list</a>
1406 for the function.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1407 </tr>
1408 <tr>
1409 <td><a href="#block">block</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1410 <td class="td_left">The function's <a href="#symtab">symbol table</a>
1411 containing only those symbols pertinent to the function (mostly block
1412 labels).</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1413 </tr>
1414 </tbody>
1415</table>
1416Notes:
1417<ol>
1418 <li>Note that if the linkage type is "External" then none of the
1419other fields will be present as the function is defined elsewhere.</li>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1420</ol>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]1421
1422<!-- _______________________________________________________________________ -->
1423<div class="doc_subsubsection"><a name="funclinkage_and_visibility">Linkage and
1424 visibility word</a>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]1425</div>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]1426<div class="doc_text">
1427
1428<table>
1429 <tbody>
1430 <tr>
1431 <th><b>Type</b></th>
1432 <th class="td_left"><b>Field Description</b></th>
1433 </tr>
1434 <tr>
1435 <td><a href="#bit">bit(0-15)</a></td>
1436 <td class="td_left">The linkage type of the function: 0=External, 1=Weak,
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1437 2=Appending, 3=Internal, 4=LinkOnce, 5=DllImport,
1438 6=DllExport<sup>1</sup></td>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]1439 </tr>
1440 <tr>
Anton Korobeynikovdaa31892007-01-23 12:43:53 +0000[diff] [blame]1441 <td><a href="#bit">bit(16-18)</a></td>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]1442 <td class="td_left">Visibility style: 0=Default, 1=Hidden.</td>
1443 </tr>
Anton Korobeynikovdaa31892007-01-23 12:43:53 +0000[diff] [blame]1444 <tr>
1445 <td><a href="#bit">bit(19-31)</a></td>
Reid Spencerc4a8d392007-01-31 00:26:08 +0000[diff] [blame]1446 <td class="td_left">Currently unassigned.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1447 </tr>
1448 </tbody>
1449</table>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]1450</div>
Reid Spencerc4a8d392007-01-31 00:26:08 +0000[diff] [blame]1451
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]1452<!-- _______________________________________________________________________ -->
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1453<div class="doc_subsection"><a name="instructionlist">Instruction List</a></div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]1454<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1455<p>The instructions in a function are written as a simple list. Basic
1456blocks are inferred by the terminating instruction types. The format of
1457the block is given in the following table.</p>
1458<table>
1459 <tbody>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1460 <tr>
1461 <th><b>Type</b></th>
1462 <th class="td_left"><b>Field Description</b></th>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1463 </tr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1464 <tr>
1465 <td><a href="#block">block</a><br>
1466 </td>
1467 <td class="td_left">Instruction list identifier (0x07) + size<br>
1468 </td>
1469 </tr>
1470 <tr>
1471 <td><a href="#instruction">instruction</a>+</td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1472 <td class="td_left">An instruction. Instructions have a variety of
1473 formats. See <a href="#instruction">Instructions</a> for details.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1474 </tr>
1475 </tbody>
1476</table>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]1477</div>
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]1478
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1479<!-- _______________________________________________________________________ -->
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]1480<div class="doc_subsection"><a name="instructions">Instructions</a></div>
1481
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1482<div class="doc_text">
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]1483<p>Instructions are written out one at a time as distinct units. Each
1484instruction
1485record contains at least an <a href="#opcodes">opcode</a> and a type field,
Chris Lattner49b16022005-11-05 22:32:06 +0000[diff] [blame]1486and may contain a <a href="#instoperands">list of operands</a> (whose
1487interpretation depends on the opcode). Based on the number of operands, the
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]1488<a href="#instencode">instruction is encoded</a> in a
1489dense format that tries to encoded each instruction into 32-bits if
1490possible. </p>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1491</div>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1492
1493<!-- _______________________________________________________________________ -->
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]1494<div class="doc_subsubsection"><a name="opcodes">Instruction Opcodes</a></div>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1495<div class="doc_text">
1496 <p>Instructions encode an opcode that identifies the kind of instruction.
1497 Opcodes are an enumerated integer value. The specific values used depend on
1498 the version of LLVM you're using. The opcode values are defined in the
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]1499 <a href="http://llvm.org/cvsweb/cvsweb.cgi/llvm/include/llvm/Instruction.def">
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1500 <tt>include/llvm/Instruction.def</tt></a> file. You should check there for the
1501 most recent definitions. The table below provides the opcodes defined as of
Nate Begeman52ca9e42004-08-27 07:59:37 +0000[diff] [blame]1502 the writing of this document. The table associates each opcode mnemonic with
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1503 its enumeration value and the bytecode and LLVM version numbers in which the
1504 opcode was introduced.</p>
1505 <table>
1506 <tbody>
1507 <tr>
1508 <th>Opcode</th>
1509 <th>Number</th>
1510 <th>Bytecode Version</th>
1511 <th>LLVM Version</th>
1512 </tr>
1513 <tr><td colspan="4"><b>Terminator Instructions</b></td></tr>
1514 <tr><td>Ret</td><td>1</td><td>1</td><td>1.0</td></tr>
1515 <tr><td>Br</td><td>2</td><td>1</td><td>1.0</td></tr>
1516 <tr><td>Switch</td><td>3</td><td>1</td><td>1.0</td></tr>
1517 <tr><td>Invoke</td><td>4</td><td>1</td><td>1.0</td></tr>
1518 <tr><td>Unwind</td><td>5</td><td>1</td><td>1.0</td></tr>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1519 <tr><td>Unreachable</td><td>6</td><td>1</td><td>1.4</td></tr>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1520 <tr><td colspan="4"><b>Binary Operators</b></td></tr>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1521 <tr><td>Add</td><td>7</td><td>1</td><td>1.0</td></tr>
1522 <tr><td>Sub</td><td>8</td><td>1</td><td>1.0</td></tr>
1523 <tr><td>Mul</td><td>9</td><td>1</td><td>1.0</td></tr>
Reid Spencer4c160692007-01-31 01:18:59 +0000[diff] [blame]1524 <tr><td>UDiv</td><td>10</td><td>6</td><td>1.9</td></tr>
1525 <tr><td>SDiv</td><td>11</td><td>6</td><td>1.9</td></tr>
1526 <tr><td>FDiv</td><td>12</td><td>6</td><td>1.9</td></tr>
1527 <tr><td>URem</td><td>13</td><td>6</td><td>1.9</td></tr>
1528 <tr><td>SRem</td><td>14</td><td>6</td><td>1.9</td></tr>
1529 <tr><td>FRem</td><td>15</td><td>6</td><td>1.9</td></tr>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1530 <tr><td colspan="4"><b>Logical Operators</b></td></tr>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1531 <tr><td>Shl</td><td>16</td><td>1</td><td>1.0</td></tr>
1532 <tr><td>LShr</td><td>17</td><td>6</td><td>1.9</td></tr>
1533 <tr><td>AShr</td><td>18</td><td>6</td><td>1.9</td></tr>
1534 <tr><td>And</td><td>19</td><td>1</td><td>1.0</td></tr>
1535 <tr><td>Or</td><td>20</td><td>1</td><td>1.0</td></tr>
1536 <tr><td>Xor</td><td>21</td><td>1</td><td>1.0</td></tr>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1537 <tr><td colspan="4"><b>Memory Operators</b></td></tr>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1538 <tr><td>Malloc</td><td>22</td><td>1</td><td>1.0</td></tr>
1539 <tr><td>Free</td><td>23</td><td>1</td><td>1.0</td></tr>
1540 <tr><td>Alloca</td><td>24</td><td>1</td><td>1.0</td></tr>
1541 <tr><td>Load</td><td>25</td><td>1</td><td>1.0</td></tr>
1542 <tr><td>Store</td><td>26</td><td>1</td><td>1.0</td></tr>
1543 <tr><td>GetElementPtr</td><td>27</td><td>1</td><td>1.0</td></tr>
Reid Spencerfec152b2007-01-31 00:38:46 +0000[diff] [blame]1544 <tr><td colspan="4"><b>Cast Operators</b></td></tr>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1545 <tr><td>Trunc</td><td>28</td><td>7</td><td>2.0</td></tr>
1546 <tr><td>ZExt</td><td>29</td><td>7</td><td>2.0</td></tr>
1547 <tr><td>SExt</td><td>30</td><td>7</td><td>2.0</td></tr>
1548 <tr><td>FPToUI</td><td>31</td><td>7</td><td>2.0</td></tr>
1549 <tr><td>FPToSI</td><td>32</td><td>7</td><td>2.0</td></tr>
1550 <tr><td>UIToFP</td><td>33</td><td>7</td><td>2.0</td></tr>
1551 <tr><td>SIToFP</td><td>34</td><td>7</td><td>2.0</td></tr>
1552 <tr><td>FPTrunc</td><td>35</td><td>7</td><td>2.0</td></tr>
1553 <tr><td>FPExt</td><td>36</td><td>7</td><td>2.0</td></tr>
1554 <tr><td>PtrToInt</td><td>37</td><td>7</td><td>2.0</td></tr>
1555 <tr><td>IntToPtr</td><td>38</td><td>7</td><td>2.0</td></tr>
1556 <tr><td>BitCast</td><td>39</td><td>7</td><td>2.0</td></tr>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1557 <tr><td colspan="4"><b>Other Operators</b></td></tr>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1558 <tr><td>ICmp</td><td>40</td><td>7</td><td>2.0</td></tr>
1559 <tr><td>FCmp</td><td>41</td><td>7</td><td>2.0</td></tr>
1560 <tr><td>PHI</td><td>42</td><td>1</td><td>1.0</td></tr>
1561 <tr><td>Call</td><td>43</td><td>1</td><td>1.0</td></tr>
Reid Spencerfec152b2007-01-31 00:38:46 +0000[diff] [blame]1562 <tr><td>Select</td><td>44</td><td>2</td><td>1.2</td></tr>
1563 <tr><td>UserOp1</td><td>45</td><td>1</td><td>1.0</td></tr>
1564 <tr><td>UserOp2</td><td>46</td><td>1</td><td>1.0</td></tr>
1565 <tr><td>VAArg</td><td>47</td><td>5</td><td>1.5</td></tr>
1566 <tr><td>ExtractElement</td><td>48</td><td>5</td><td>1.5</td></tr>
1567 <tr><td>InsertElement</td><td>49</td><td>5</td><td>1.5</td></tr>
1568 <tr><td>ShuffleElement</td><td>50</td><td>5</td><td>1.5</td></tr>
Reid Spencera5681772005-05-14 00:06:06 +0000[diff] [blame]1569 <tr><td colspan="4">
1570 <b>Pseudo Instructions<a href="#pi_note">*</a></b>
1571 </td></tr>
1572 <tr><td>Invoke+CC </td><td>56</td><td>5</td><td>1.5</td></tr>
1573 <tr><td>Invoke+FastCC</td><td>57</td><td>5</td><td>1.5</td></tr>
1574 <tr><td>Call+CC</td><td>58</td><td>5</td><td>1.5</td></tr>
1575 <tr><td>Call+FastCC+TailCall</td><td>59</td><td>5</td><td>1.5</td></tr>
1576 <tr><td>Call+FastCC</td><td>60</td><td>5</td><td>1.5</td></tr>
1577 <tr><td>Call+CCC+TailCall</td><td>61</td><td>5</td><td>1.5</td></tr>
1578 <tr><td>Load+Volatile</td><td>62</td><td>3</td><td>1.3</td></tr>
1579 <tr><td>Store+Volatile</td><td>63</td><td>3</td><td>1.3</td></tr>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1580 </tbody>
1581 </table>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1582
Reid Spencera5681772005-05-14 00:06:06 +0000[diff] [blame]1583<p><b><a name="pi_note">* Note: </a></b>
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]1584These aren't really opcodes from an LLVM language perspective. They encode
Reid Spencera5681772005-05-14 00:06:06 +0000[diff] [blame]1585information into other opcodes without reserving space for that information.
1586For example, opcode=63 is a Volatile Store. The opcode for this
1587instruction is 25 (Store) but we encode it as 63 to indicate that is a Volatile
1588Store. The same is done for the calling conventions and tail calls.
1589In each of these entries in range 56-63, the opcode is documented as the base
1590opcode (Invoke, Call, Store) plus some set of modifiers, as follows:</p>
1591<dl>
1592 <dt>CC</dt>
Chris Lattner120bc6d2005-05-14 01:30:15 +0000[diff] [blame]1593 <dd>This means an arbitrary calling convention is specified
1594 in a VBR that follows the opcode. This is used when the instruction cannot
1595 be encoded with one of the more compact forms.
Reid Spencera5681772005-05-14 00:06:06 +0000[diff] [blame]1596 </dd>
1597 <dt>FastCC</dt>
1598 <dd>This indicates that the Call or Invoke is using the FastCC calling
Chris Lattner120bc6d2005-05-14 01:30:15 +0000[diff] [blame]1599 convention.</dd>
Reid Spencera5681772005-05-14 00:06:06 +0000[diff] [blame]1600 <dt>CCC</dt>
Chris Lattner120bc6d2005-05-14 01:30:15 +0000[diff] [blame]1601 <dd>This indicates that the Call or Invoke is using the native "C" calling
1602 convention.</dd>
Reid Spencera5681772005-05-14 00:06:06 +0000[diff] [blame]1603 <dt>TailCall</dt>
Chris Lattner120bc6d2005-05-14 01:30:15 +0000[diff] [blame]1604 <dd>This indicates that the Call has the 'tail' modifier.</dd>
Reid Spencera5681772005-05-14 00:06:06 +0000[diff] [blame]1605</dl>
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]1606</div>
1607
Chris Lattner49b16022005-11-05 22:32:06 +0000[diff] [blame]1608<!-- _______________________________________________________________________ -->
1609<div class="doc_subsubsection"><a name="instoperands">Instruction
1610Operands</a></div>
1611
1612<div class="doc_text">
1613<p>
1614Based on the instruction opcode and type, the bytecode format implicitly (to
1615save space) specifies the interpretation of the operand list. For most
1616instructions, the type of each operand is implicit from the type of the
1617instruction itself (e.g. the type of operands of a binary operator must match
1618the type of the instruction). As such, the bytecode format generally only
1619encodes the value number of the operand, not the type.</p>
1620
1621<p>In some cases, however, this is not sufficient. This section enumerates
1622those cases:</p>
1623
1624<ul>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1625 <li>getelementptr: the slot numbers for sequential type indexes are shifted
1626 up two bits. This allows the low order bits will encode the type of index
1627 used, as follows: 0=uint, 1=int, 2=ulong, 3=long.</li>
1628 <li>cast: the result type number is encoded as the second operand.</li>
1629 <li>alloca/malloc: If the allocation has an explicit alignment, the log2 of
1630 the alignment is encoded as the second operand.</li>
1631 <li>call: If the tail marker and calling convention cannot be
1632 <a href="#pi_note">encoded into the opcode</a> of the call, it is passed as
1633 an additional operand. The low bit of the operand is a flag indicating
1634 whether the call is a tail call. The rest of the bits contain the calling
1635 convention number (shifted left by one bit).</li>
Chris Lattner49b16022005-11-05 22:32:06 +0000[diff] [blame]1636</ul>
1637</div>
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]1638
1639<!-- _______________________________________________________________________ -->
1640<div class="doc_subsubsection"><a name="instencode">Instruction
1641Encoding</a></div>
1642
1643<div class="doc_text">
1644<p>For brevity, instructions are written in one of four formats,
1645depending on the number of operands to the instruction. Each
1646instruction begins with a <a href="#uint32_vbr">uint32_vbr</a> that
1647encodes the type of the instruction as well as other things. The tables
1648that follow describe the format of this first part of each instruction.</p>
1649<p><b>Instruction Format 0</b></p>
1650<p>This format is used for a few instructions that can't easily be
1651shortened because they have large numbers of operands (e.g. PHI Node or
1652getelementptr). Each of the opcode, type, and operand fields is found in
1653successive fields.</p>
1654<table>
1655 <tbody>
1656 <tr>
1657 <th><b>Type</b></th>
1658 <th class="td_left"><b>Field Description</b></th>
1659 </tr>
1660 <tr>
1661 <td><a href="#uint32_vbr">uint32_vbr</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1662 <td class="td_left">Specifies the opcode of the instruction. Note that
1663 for compatibility with the other instruction formats, the opcode is
1664 shifted left by 2 bits. Bits 0 and 1 must have value zero for this
1665 format.</td>
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]1666 </tr>
1667 <tr>
1668 <td><a href="#uint24_vbr">uint24_vbr</a></td>
1669 <td class="td_left">Provides the type slot number of the result type of
1670 the instruction.</td>
1671 </tr>
1672 <tr>
1673 <td><a href="#uint32_vbr">uint32_vbr</a></td>
1674 <td class="td_left">The number of operands that follow.</td>
1675 </tr>
1676 <tr>
1677 <td><a href="#uint32_vbr">uint32_vbr</a>+</td>
1678 <td class="td_left">The slot number of the value(s) for the operand(s).
Chris Lattner49b16022005-11-05 22:32:06 +0000[diff] [blame]1679 </td>
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]1680 </tr>
1681 </tbody>
1682</table>
Chris Lattner49b16022005-11-05 22:32:06 +0000[diff] [blame]1683
Chris Lattnerf97fa592005-11-05 22:20:06 +0000[diff] [blame]1684<p><b>Instruction Format 1</b></p>
1685<p>This format encodes the opcode, type and a single operand into a
1686single <a href="#uint32_vbr">uint32_vbr</a> as follows:</p>
1687<table>
1688 <tbody>
1689 <tr>
1690 <th><b>Bits</b></th>
1691 <th><b>Type</b></th>
1692 <th class="td_left"><b>Field Description</b></th>
1693 </tr>
1694 <tr>
1695 <td>0-1</td>
1696 <td>constant "1"</td>
1697 <td class="td_left">These two bits must be the value 1 which identifies
1698 this as an instruction of format 1.</td>
1699 </tr>
1700 <tr>
1701 <td>2-7</td>
1702 <td><a href="#instructions">opcode</a></td>
1703 <td class="td_left">Specifies the opcode of the instruction. Note that
1704 the maximum opcode value is 63.</td>
1705 </tr>
1706 <tr>
1707 <td>8-19</td>
1708 <td><a href="#unsigned">unsigned</a></td>
1709 <td class="td_left">Specifies the slot number of the type for this
1710 instruction. Maximum slot number is 2<sup>12</sup>-1=4095.</td>
1711 </tr>
1712 <tr>
1713 <td>20-31</td>
1714 <td><a href="#unsigned">unsigned</a></td>
1715 <td class="td_left">Specifies the slot number of the value for the
1716 first operand. Maximum slot number is 2<sup>12</sup>-1=4095. Note that
1717 the value 2<sup>12</sup>-1 denotes zero operands.</td>
1718 </tr>
1719 </tbody>
1720</table>
1721<p><b>Instruction Format 2</b></p>
1722<p>This format encodes the opcode, type and two operands into a single <a
1723 href="#uint32_vbr">uint32_vbr</a> as follows:</p>
1724<table>
1725 <tbody>
1726 <tr>
1727 <th><b>Bits</b></th>
1728 <th><b>Type</b></th>
1729 <th class="td_left"><b>Field Description</b></th>
1730 </tr>
1731 <tr>
1732 <td>0-1</td>
1733 <td>constant "2"</td>
1734 <td class="td_left">These two bits must be the value 2 which identifies
1735 this as an instruction of format 2.</td>
1736 </tr>
1737 <tr>
1738 <td>2-7</td>
1739 <td><a href="#instructions">opcode</a></td>
1740 <td class="td_left">Specifies the opcode of the instruction. Note that
1741 the maximum opcode value is 63.</td>
1742 </tr>
1743 <tr>
1744 <td>8-15</td>
1745 <td><a href="#unsigned">unsigned</a></td>
1746 <td class="td_left">Specifies the slot number of the type for this
1747 instruction. Maximum slot number is 2<sup>8</sup>-1=255.</td>
1748 </tr>
1749 <tr>
1750 <td>16-23</td>
1751 <td><a href="#unsigned">unsigned</a></td>
1752 <td class="td_left">Specifies the slot number of the value for the first
1753 operand. Maximum slot number is 2<sup>8</sup>-1=255.</td>
1754 </tr>
1755 <tr>
1756 <td>24-31</td>
1757 <td><a href="#unsigned">unsigned</a></td>
1758 <td class="td_left">Specifies the slot number of the value for the second
1759 operand. Maximum slot number is 2<sup>8</sup>-1=255.</td>
1760 </tr>
1761 </tbody>
1762</table>
1763<p><b>Instruction Format 3</b></p>
1764<p>This format encodes the opcode, type and three operands into a
1765single <a href="#uint32_vbr">uint32_vbr</a> as follows:</p>
1766<table>
1767 <tbody>
1768 <tr>
1769 <th><b>Bits</b></th>
1770 <th><b>Type</b></th>
1771 <th class="td_left"><b>Field Description</b></th>
1772 </tr>
1773 <tr>
1774 <td>0-1</td>
1775 <td>constant "3"</td>
1776 <td class="td_left">These two bits must be the value 3 which identifies
1777 this as an instruction of format 3.</td>
1778 </tr>
1779 <tr>
1780 <td>2-7</td>
1781 <td><a href="#instructions">opcode</a></td>
1782 <td class="td_left">Specifies the opcode of the instruction. Note that
1783 the maximum opcode value is 63.</td>
1784 </tr>
1785 <tr>
1786 <td>8-13</td>
1787 <td><a href="#unsigned">unsigned</a></td>
1788 <td class="td_left">Specifies the slot number of the type for this
1789 instruction. Maximum slot number is 2<sup>6</sup>-1=63.</td>
1790 </tr>
1791 <tr>
1792 <td>14-19</td>
1793 <td><a href="#unsigned">unsigned</a></td>
1794 <td class="td_left">Specifies the slot number of the value for the first
1795 operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
1796 </tr>
1797 <tr>
1798 <td>20-25</td>
1799 <td><a href="#unsigned">unsigned</a></td>
1800 <td class="td_left">Specifies the slot number of the value for the second
1801 operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
1802 </tr>
1803 <tr>
1804 <td>26-31</td>
1805 <td><a href="#unsigned">unsigned</a></td>
1806 <td class="td_left">Specifies the slot number of the value for the third
1807 operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
1808 </tr>
1809 </tbody>
1810</table>
1811</div>
Reid Spencera5681772005-05-14 00:06:06 +0000[diff] [blame]1812
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]1813<!-- _______________________________________________________________________ -->
Reid Spencerb39021b2004-05-23 17:05:09 +0000[diff] [blame]1814<div class="doc_subsection"><a name="symtab">Symbol Table</a> </div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]1815<div class="doc_text">
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1816<p>A symbol table can be put out in conjunction with a module or a function. A
1817symbol table has a list of name/type associations followed by a list of
1818name/value associations. The name/value associations are organized into "type
1819planes" so that all values of a common type are listed together. Each type
1820plane starts with the number of entries in the plane and the type slot number
1821for all the values in that plane (so the type can be looked up in the global
1822type pool). For each entry in a type plane, the slot number of the value and
1823the name associated with that value are written. The format is given in the
1824table below. </p>
Reid Spencer2cc36152004-07-05 19:04:27 +0000[diff] [blame]1825<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1826 <tbody>
1827 <tr>
1828 <th><b>Type</b></th>
1829 <th class="td_left"><b>Field Description</b></th>
1830 </tr>
1831 <tr>
1832 <td><a href="#block">block</a><br>
1833 </td>
1834 <td class="td_left">Symbol Table Identifier (0x04)</td>
1835 </tr>
1836 <tr>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1837 <td><a href="#llist">llist</a>(<a href="#symtab_entry">type_entry</a>)
1838 </td>
Reid Spencer8996e552004-08-17 00:49:03 +0000[diff] [blame]1839 <td class="td_left">A length list of symbol table entries for
1840 <tt>Type</tt>s
1841 </td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1842 </tr>
1843 <tr>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1844 <td><a href="#zlist">llist</a>(<a href="#symtab_plane">symtab_plane</a>)
1845 </td>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1846 <td class="td_left">A length list of "type planes" of symbol table
Reid Spencer8996e552004-08-17 00:49:03 +0000[diff] [blame]1847 entries for <tt>Value</tt>s</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1848 </tr>
1849 </tbody>
Reid Spencerb39021b2004-05-23 17:05:09 +0000[diff] [blame]1850</table>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]1851</div>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1852
1853<!-- _______________________________________________________________________ -->
1854<div class="doc_subsubsection"> <a name="type_entry">Symbol Table Type
1855Entry</a>
1856</div>
1857<div class="doc_text">
1858<p>A symbol table type entry associates a name with a type. The name is provided
1859simply as an array of chars. The type is provided as a type slot number (index)
1860into the global type pool. The format is given in the following table:</p>
1861<table>
1862 <tbody>
1863 <tr>
1864 <th><b>Type</b></th>
1865 <th class="td_left"><b>Field Description</b></th>
1866 </tr>
1867 <tr>
1868 <td><a href="#uint32_vbr">uint24_vbr</a></td>
1869 <td class="td_left">Type slot number of the type being given a
1870 name relative to the global type pool.
1871 </td>
1872 </tr>
1873 <tr>
1874 <td><a href="#uint32_vbr">uint32_vbr</a></td>
1875 <td class="td_left">Length of the character array that follows.</td>
1876 </tr>
1877 <tr>
1878 <td><a href="#char">char</a>+</td>
1879 <td class="td_left">The characters of the name.</td>
1880 </tr>
1881 </tbody>
1882</table>
1883</div>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1884<!-- _______________________________________________________________________ -->
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1885<div class="doc_subsubsection"> <a name="symtab_plane">Symbol Table
1886Plane</a>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1887</div>
1888<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1889<p>A symbol table plane provides the symbol table entries for all
1890values of a common type. The encoding is given in the following table:</p>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1891<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1892 <tbody>
1893 <tr>
1894 <th><b>Type</b></th>
1895 <th class="td_left"><b>Field Description</b></th>
1896 </tr>
1897 <tr>
1898 <td><a href="#uint32_vbr">uint32_vbr</a></td>
1899 <td class="td_left">Number of entries in this plane.</td>
1900 </tr>
1901 <tr>
1902 <td><a href="#uint32_vbr">uint32_vbr</a></td>
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1903 <td class="td_left">Type slot number of type for all values in this plane.
1904 </td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1905 </tr>
1906 <tr>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1907 <td><a href="#value_entry">value_entry</a>+</td>
1908 <td class="td_left">The symbol table entries for to associate values with
1909 names.</td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1910 </tr>
1911 </tbody>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1912</table>
1913</div>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1914<!-- _______________________________________________________________________ -->
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1915<div class="doc_subsubsection"><a name="value_entry">Symbol Table Value
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1916Entry</a>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1917</div>
1918<div class="doc_text">
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1919<p>A symbol table value entry provides the assocation between a value and the
1920name given to the value. The value is referenced by its slot number. The
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1921format is given in the following table:</p>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1922<table>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1923 <tbody>
1924 <tr>
1925 <th><b>Type</b></th>
1926 <th class="td_left"><b>Field Description</b></th>
1927 </tr>
1928 <tr>
1929 <td><a href="#uint32_vbr">uint24_vbr</a></td>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1930 <td class="td_left">Value slot number of the value being given a name.
Reid Spencer8996e552004-08-17 00:49:03 +0000[diff] [blame]1931 </td>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1932 </tr>
1933 <tr>
1934 <td><a href="#uint32_vbr">uint32_vbr</a></td>
1935 <td class="td_left">Length of the character array that follows.</td>
1936 </tr>
1937 <tr>
1938 <td><a href="#char">char</a>+</td>
1939 <td class="td_left">The characters of the name.</td>
1940 </tr>
1941 </tbody>
Reid Spencer51f31e02004-07-05 22:28:02 +0000[diff] [blame]1942</table>
1943</div>
Reid Spencer09daa632004-08-18 20:06:19 +0000[diff] [blame]1944
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]1945<!-- *********************************************************************** -->
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1946<div class="doc_section"> <a name="versiondiffs">Version Differences</a>
1947</div>
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]1948<!-- *********************************************************************** -->
1949<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1950<p>This section describes the differences in the Bytecode Format across
1951LLVM
1952versions. The versions are listed in reverse order because it assumes
1953the current version is as documented in the previous sections. Each
1954section here
Chris Lattner1cc070c2004-07-05 18:05:48 +0000[diff] [blame]1955describes the differences between that version and the one that <i>follows</i>.
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]1956</p>
1957</div>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1958
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]1959<!-- _______________________________________________________________________ -->
Reid Spencer43dfdb72004-08-18 20:17:05 +0000[diff] [blame]1960<div class="doc_subsection"><a name="vers13">Version 1.3 Differences From
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1961 1.4</a></div>
Reid Spencercf549e12004-08-17 07:43:43 +0000[diff] [blame]1962<!-- _______________________________________________________________________ -->
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1963
1964<div class="doc_subsubsection">Unreachable Instruction</div>
1965<div class="doc_text">
1966 <p>The LLVM <a href="LangRef.html#i_unreachable">Unreachable</a> instruction
1967 was added in version 1.4 of LLVM. This caused all instruction numbers after
1968 it to shift down by one.</p>
1969</div>
1970
1971<div class="doc_subsubsection">Function Flags</div>
1972<div class="doc_text">
1973 <p>LLVM bytecode versions prior to 1.4 did not include the 5 bit offset
1974 in <a href="#funcfield">the function list</a> in the <a
1975 href="#globalinfo">Module Global Info</a> block.</p>
1976</div>
1977
1978<div class="doc_subsubsection">Function Flags</div>
1979<div class="doc_text">
1980 <p>LLVM bytecode versions prior to 1.4 did not include the 'undef' constant
Reid Spencere1888ee2007-02-02 02:30:19 +0000[diff] [blame^]1981 value, which affects the encoding of <a href="#constant">Constant Fields</a>.
1982 </p>
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1983</div>
1984
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1985
Reid Spencercf549e12004-08-17 07:43:43 +0000[diff] [blame]1986<!-- _______________________________________________________________________ -->
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1987<div class="doc_subsection"><a name="vers12">Version 1.2 Differences
1988From 1.3</a></div>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]1989<!-- _______________________________________________________________________ -->
Chris Lattnera1dad812004-10-16 18:03:55 +0000[diff] [blame]1990
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]1991<div class="doc_subsubsection">Type Derives From Value</div>
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]1992<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]1993<p>In version 1.2, the Type class in the LLVM IR derives from the Value
1994class. This is not the case in version 1.3. Consequently, in version
19951.2 the notion of a "Type Type" was used to write out values that were
1996Types. The types always occuped plane 12 (corresponding to the
1997TypeTyID) of any type planed set of values. In 1.3 this representation
1998is not convenient because the TypeTyID (12) is not present and its
1999value is now used for LabelTyID. Consequently, the data structures
2000written that involve types do so by writing all the types first and
2001then each of the value planes according to those types. In version 1.2,
2002the types would have been written intermingled with the values.</p>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]2003</div>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]2004<!-- _______________________________________________________________________ -->
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]2005<div class="doc_subsubsection">Restricted getelementptr Types</div>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]2006<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]2007<p>In version 1.2, the getelementptr instruction required a ubyte type
2008index for accessing a structure field and a long type index for
2009accessing an array element. Consequently, it was only possible to
2010access structures of 255 or fewer elements. Starting in version 1.3,
2011this restriction was lifted. Structures must now be indexed with uint
2012constants. Arrays may now be indexed with int, uint, long, or ulong
2013typed values. The consequence of this was that the bytecode format had
2014to change in order to accommodate the larger range of structure indices.</p>
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]2015</div>
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]2016<!-- _______________________________________________________________________ -->
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]2017<div class="doc_subsubsection">Short Block Headers</div>
2018<div class="doc_text">
2019<p>In version 1.2, block headers were always 8 bytes being comprised of
2020both an unsigned integer type and an unsigned integer size. For very
2021small modules, these block headers turn out to be a large fraction of
2022the total bytecode file size. In an attempt to make these small files
2023smaller, the type and size information was encoded into a single
2024unsigned integer (4 bytes) comprised of 5 bits for the block type
2025(maximum 31 block types) and 27 bits for the block size (max
2026~134MBytes). These limits seemed sufficient for any blocks or sizes
2027forseen in the future. Note that the module block, which encloses all
2028the other blocks is still written as 8 bytes since bytecode files
2029larger than 134MBytes might be possible.</p>
2030</div>
2031<!-- _______________________________________________________________________ -->
2032<div class="doc_subsubsection">Dependent Libraries and Target Triples</div>
2033<div class="doc_text">
2034<p>In version 1.2, the bytecode format does not store module's target
2035triple or dependent. These fields have been added to the end of the <a
2036 href="#globalinfo">module global info block</a>. The purpose of these
2037fields is to allow a front end compiler to specifiy that the generated
2038module is specific to a particular target triple (operating
2039system/manufacturer/processor) which makes it non-portable; and to
2040allow front end compilers to specify the list of libraries that the
2041module depends on for successful linking.</p>
2042</div>
2043<!-- _______________________________________________________________________ -->
2044<div class="doc_subsubsection">Types Restricted to 24-bits</div>
2045<div class="doc_text">
2046<p>In version 1.2, type slot identifiers were written as 32-bit VBR
2047quantities. In 1.3 this has been reduced to 24-bits in order to ensure
2048that it is not possible to overflow the type field of a global variable
2049definition. 24-bits for type slot numbers is deemed sufficient for any
2050practical use of LLVM.</p>
2051</div>
2052<!-- _______________________________________________________________________ -->
2053<!-- _______________________________________________________________________ -->
2054<div class="doc_subsection"><a name="vers11">Version 1.1 Differences
2055From 1.2 </a></div>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]2056<!-- _______________________________________________________________________ -->
2057<div class="doc_subsubsection">Explicit Primitive Zeros</div>
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]2058<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]2059<p>In version 1.1, the zero value for primitives was explicitly encoded
2060into the bytecode format. Since these zero values are constant values
2061in the LLVM IR and never change, there is no reason to explicitly
2062encode them. This explicit encoding was removed in version 1.2.</p>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]2063</div>
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]2064<!-- _______________________________________________________________________ -->
2065<div class="doc_subsubsection">Inconsistent Module Global Info</div>
2066<div class="doc_text">
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]2067<p>In version 1.1, the Module Global Info block was not aligned causing
2068the next block to be read in on an unaligned boundary. This problem was
2069corrected in version 1.2.<br>
2070<br>
2071</p>
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]2072</div>
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]2073<!-- _______________________________________________________________________ -->
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]2074<div class="doc_subsection"><a name="vers10">Version 1.0 Differences
2075From 1.1</a></div>
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]2076<div class="doc_text">
Reid Spencer1ab929c2004-07-05 08:18:07 +0000[diff] [blame]2077<p>None. Version 1.0 and 1.1 bytecode formats are identical.</p>
Reid Spencer7c76d332004-06-08 07:41:41 +0000[diff] [blame]2078</div>
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]2079<!-- *********************************************************************** -->
2080<hr>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]2081<address> <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
2082 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
2083<a href="http://validator.w3.org/check/referer"><img
2084 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
2085<a href="mailto:rspencer@x10sys.com">Reid Spencer</a> and <a
2086 href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]2087<a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]2088Last modified: $Date$
Reid Spencer50026612004-05-22 02:28:36 +0000[diff] [blame]2089</address>
Reid Spencer9bd2be22004-07-29 00:13:04 +0000[diff] [blame]2090</body>
2091</html>