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Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6 <title>Source Level Debugging with LLVM</title>
7 <link rel="stylesheet" href="llvm.css" type="text/css">
8</head>
9<body>
10
11<div class="doc_title">Source Level Debugging with LLVM</div>
12
13<table class="layout" style="width:100%">
14 <tr class="layout">
15 <td class="left">
16<ul>
17 <li><a href="#introduction">Introduction</a>
18 <ol>
19 <li><a href="#phil">Philosophy behind LLVM debugging information</a></li>
20 <li><a href="#consumers">Debug information consumers</a></li>
21 <li><a href="#debugopt">Debugging optimized code</a></li>
22 </ol></li>
23 <li><a href="#format">Debugging information format</a>
24 <ol>
25 <li><a href="#debug_info_descriptors">Debug information descriptors</a>
26 <ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]27 <li><a href="#format_compile_units">Compile unit descriptors</a></li>
28 <li><a href="#format_global_variables">Global variable descriptors</a></li>
29 <li><a href="#format_subprograms">Subprogram descriptors</a></li>
30 <li><a href="#format_blocks">Block descriptors</a></li>
31 <li><a href="#format_basic_type">Basic type descriptors</a></li>
32 <li><a href="#format_derived_type">Derived type descriptors</a></li>
33 <li><a href="#format_composite_type">Composite type descriptors</a></li>
34 <li><a href="#format_subrange">Subrange descriptors</a></li>
35 <li><a href="#format_enumeration">Enumerator descriptors</a></li>
36 <li><a href="#format_variables">Local variables</a></li>
37 </ul></li>
38 <li><a href="#format_common_intrinsics">Debugger intrinsic functions</a>
39 <ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]40 <li><a href="#format_common_declare">llvm.dbg.declare</a></li>
41 </ul></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]42 </ol></li>
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]43 <li><a href="#format_common_lifetime">Object lifetimes and scoping</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]44 <li><a href="#ccxx_frontend">C/C++ front-end specific debug information</a>
45 <ol>
46 <li><a href="#ccxx_compile_units">C/C++ source file information</a></li>
47 <li><a href="#ccxx_global_variable">C/C++ global variable information</a></li>
48 <li><a href="#ccxx_subprogram">C/C++ function information</a></li>
49 <li><a href="#ccxx_basic_types">C/C++ basic types</a></li>
50 <li><a href="#ccxx_derived_types">C/C++ derived types</a></li>
51 <li><a href="#ccxx_composite_types">C/C++ struct/union types</a></li>
52 <li><a href="#ccxx_enumeration_types">C/C++ enumeration types</a></li>
53 </ol></li>
54</ul>
55</td>
56<td class="right">
57<img src="img/venusflytrap.jpg" alt="A leafy and green bug eater" width="247"
58height="369">
59</td>
60</tr></table>
61
62<div class="doc_author">
63 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
64 and <a href="mailto:jlaskey@mac.com">Jim Laskey</a></p>
65</div>
66
67
68<!-- *********************************************************************** -->
69<div class="doc_section"><a name="introduction">Introduction</a></div>
70<!-- *********************************************************************** -->
71
72<div class="doc_text">
73
74<p>This document is the central repository for all information pertaining to
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]75 debug information in LLVM. It describes the <a href="#format">actual format
76 that the LLVM debug information</a> takes, which is useful for those
77 interested in creating front-ends or dealing directly with the information.
Chris Lattner990e7652009-07-18 21:47:15 +0000[diff] [blame]78 Further, this document provides specific examples of what debug information
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]79 for C/C++.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]80
81</div>
82
83<!-- ======================================================================= -->
84<div class="doc_subsection">
85 <a name="phil">Philosophy behind LLVM debugging information</a>
86</div>
87
88<div class="doc_text">
89
90<p>The idea of the LLVM debugging information is to capture how the important
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]91 pieces of the source-language's Abstract Syntax Tree map onto LLVM code.
92 Several design aspects have shaped the solution that appears here. The
93 important ones are:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]94
95<ul>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]96 <li>Debugging information should have very little impact on the rest of the
97 compiler. No transformations, analyses, or code generators should need to
98 be modified because of debugging information.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]99
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]100 <li>LLVM optimizations should interact in <a href="#debugopt">well-defined and
101 easily described ways</a> with the debugging information.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]102
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]103 <li>Because LLVM is designed to support arbitrary programming languages,
104 LLVM-to-LLVM tools should not need to know anything about the semantics of
105 the source-level-language.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]106
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]107 <li>Source-level languages are often <b>widely</b> different from one another.
108 LLVM should not put any restrictions of the flavor of the source-language,
109 and the debugging information should work with any language.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]110
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]111 <li>With code generator support, it should be possible to use an LLVM compiler
112 to compile a program to native machine code and standard debugging
113 formats. This allows compatibility with traditional machine-code level
114 debuggers, like GDB or DBX.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]115</ul>
116
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]117<p>The approach used by the LLVM implementation is to use a small set
118 of <a href="#format_common_intrinsics">intrinsic functions</a> to define a
119 mapping between LLVM program objects and the source-level objects. The
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]120 description of the source-level program is maintained in LLVM metadata
121 in an <a href="#ccxx_frontend">implementation-defined format</a>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]122 (the C/C++ front-end currently uses working draft 7 of
123 the <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3
124 standard</a>).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]125
126<p>When a program is being debugged, a debugger interacts with the user and
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]127 turns the stored debug information into source-language specific information.
128 As such, a debugger must be aware of the source-language, and is thus tied to
129 a specific language or family of languages.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]130
131</div>
132
133<!-- ======================================================================= -->
134<div class="doc_subsection">
135 <a name="consumers">Debug information consumers</a>
136</div>
137
138<div class="doc_text">
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]139
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]140<p>The role of debug information is to provide meta information normally
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]141 stripped away during the compilation process. This meta information provides
142 an LLVM user a relationship between generated code and the original program
143 source code.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]144
145<p>Currently, debug information is consumed by the DwarfWriter to produce dwarf
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]146 information used by the gdb debugger. Other targets could use the same
147 information to produce stabs or other debug forms.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]148
149<p>It would also be reasonable to use debug information to feed profiling tools
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]150 for analysis of generated code, or, tools for reconstructing the original
151 source from generated code.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]152
153<p>TODO - expound a bit more.</p>
154
155</div>
156
157<!-- ======================================================================= -->
158<div class="doc_subsection">
159 <a name="debugopt">Debugging optimized code</a>
160</div>
161
162<div class="doc_text">
163
164<p>An extremely high priority of LLVM debugging information is to make it
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]165 interact well with optimizations and analysis. In particular, the LLVM debug
166 information provides the following guarantees:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]167
168<ul>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]169 <li>LLVM debug information <b>always provides information to accurately read
170 the source-level state of the program</b>, regardless of which LLVM
171 optimizations have been run, and without any modification to the
172 optimizations themselves. However, some optimizations may impact the
173 ability to modify the current state of the program with a debugger, such
174 as setting program variables, or calling functions that have been
175 deleted.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]176
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]177 <li>LLVM optimizations gracefully interact with debugging information. If
178 they are not aware of debug information, they are automatically disabled
179 as necessary in the cases that would invalidate the debug info. This
180 retains the LLVM features, making it easy to write new
181 transformations.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]182
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]183 <li>As desired, LLVM optimizations can be upgraded to be aware of the LLVM
184 debugging information, allowing them to update the debugging information
185 as they perform aggressive optimizations. This means that, with effort,
186 the LLVM optimizers could optimize debug code just as well as non-debug
187 code.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]188
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]189 <li>LLVM debug information does not prevent many important optimizations from
190 happening (for example inlining, basic block reordering/merging/cleanup,
191 tail duplication, etc), further reducing the amount of the compiler that
192 eventually is "aware" of debugging information.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]193
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]194 <li>LLVM debug information is automatically optimized along with the rest of
195 the program, using existing facilities. For example, duplicate
196 information is automatically merged by the linker, and unused information
197 is automatically removed.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]198</ul>
199
200<p>Basically, the debug information allows you to compile a program with
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]201 "<tt>-O0 -g</tt>" and get full debug information, allowing you to arbitrarily
202 modify the program as it executes from a debugger. Compiling a program with
203 "<tt>-O3 -g</tt>" gives you full debug information that is always available
204 and accurate for reading (e.g., you get accurate stack traces despite tail
205 call elimination and inlining), but you might lose the ability to modify the
206 program and call functions where were optimized out of the program, or
207 inlined away completely.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]208
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]209<p><a href="TestingGuide.html#quicktestsuite">LLVM test suite</a> provides a
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]210 framework to test optimizer's handling of debugging information. It can be
211 run like this:</p>
Devang Patel7717e542008-11-21 19:35:57 +0000[diff] [blame]212
213<div class="doc_code">
214<pre>
215% cd llvm/projects/test-suite/MultiSource/Benchmarks # or some other level
216% make TEST=dbgopt
217</pre>
218</div>
219
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]220<p>This will test impact of debugging information on optimization passes. If
221 debugging information influences optimization passes then it will be reported
222 as a failure. See <a href="TestingGuide.html">TestingGuide</a> for more
223 information on LLVM test infrastructure and how to run various tests.</p>
Devang Patel7717e542008-11-21 19:35:57 +0000[diff] [blame]224
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]225</div>
226
227<!-- *********************************************************************** -->
228<div class="doc_section">
229 <a name="format">Debugging information format</a>
230</div>
231<!-- *********************************************************************** -->
232
233<div class="doc_text">
234
235<p>LLVM debugging information has been carefully designed to make it possible
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]236 for the optimizer to optimize the program and debugging information without
237 necessarily having to know anything about debugging information. In
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]238 particular, te use of metadadta avoids duplicated dubgging information from
239 the beginning, and the global dead code elimination pass automatically
240 deletes debugging information for a function if it decides to delete the
241 function. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]242
243<p>To do this, most of the debugging information (descriptors for types,
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]244 variables, functions, source files, etc) is inserted by the language
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]245 front-end in the form of LLVM metadata. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]246
247<p>Debug information is designed to be agnostic about the target debugger and
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]248 debugging information representation (e.g. DWARF/Stabs/etc). It uses a
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]249 generic pass to decode the information that represents variables, types,
250 functions, namespaces, etc: this allows for arbitrary source-language
251 semantics and type-systems to be used, as long as there is a module
252 written for the target debugger to interpret the information. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]253
254<p>To provide basic functionality, the LLVM debugger does have to make some
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]255 assumptions about the source-level language being debugged, though it keeps
256 these to a minimum. The only common features that the LLVM debugger assumes
257 exist are <a href="#format_compile_units">source files</a>,
258 and <a href="#format_global_variables">program objects</a>. These abstract
259 objects are used by a debugger to form stack traces, show information about
260 local variables, etc.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]261
262<p>This section of the documentation first describes the representation aspects
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]263 common to any source-language. The <a href="#ccxx_frontend">next section</a>
264 describes the data layout conventions used by the C and C++ front-ends.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]265
266</div>
267
268<!-- ======================================================================= -->
269<div class="doc_subsection">
270 <a name="debug_info_descriptors">Debug information descriptors</a>
271</div>
272
273<div class="doc_text">
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]274
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]275<p>In consideration of the complexity and volume of debug information, LLVM
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]276 provides a specification for well formed debug descriptors. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]277
278<p>Consumers of LLVM debug information expect the descriptors for program
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]279 objects to start in a canonical format, but the descriptors can include
280 additional information appended at the end that is source-language
281 specific. All LLVM debugging information is versioned, allowing backwards
282 compatibility in the case that the core structures need to change in some
283 way. Also, all debugging information objects start with a tag to indicate
284 what type of object it is. The source-language is allowed to define its own
285 objects, by using unreserved tag numbers. We recommend using with tags in
Benjamin Kramer5fb9d7e2009-10-12 14:46:08 +0000[diff] [blame]286 the range 0x1000 through 0x2000 (there is a defined enum DW_TAG_user_base =
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]287 0x1000.)</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]288
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]289<p>The fields of debug descriptors used internally by LLVM
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]290 are restricted to only the simple data types <tt>int</tt>, <tt>uint</tt>,
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]291 <tt>bool</tt>, <tt>float</tt>, <tt>double</tt>, <tt>mdstring</tt> and
292 <tt>mdnode</tt>. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]293
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]294<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]295<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]296!1 = metadata !{
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]297 uint, ;; A tag
298 ...
299}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]300</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]301</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]302
303<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]304 <tt>uint</tt> containing a tag value identifying the content of the
305 descriptor. The remaining fields are specific to the descriptor. The values
306 of tags are loosely bound to the tag values of DWARF information entries.
307 However, that does not restrict the use of the information supplied to DWARF
308 targets. To facilitate versioning of debug information, the tag is augmented
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]309 with the current debug version (LLVMDebugVersion = 7 << 16 or 0x70000 or
310 458752.)</a></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]311
312<p>The details of the various descriptors follow.</p>
313
314</div>
315
316<!-- ======================================================================= -->
317<div class="doc_subsubsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]318 <a name="format_compile_units">Compile unit descriptors</a>
319</div>
320
321<div class="doc_text">
322
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]323<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]324<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]325!0 = metadata !{
326 i32, ;; Tag = 17 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
327 ;; (DW_TAG_compile_unit)
328 i32, ;; Unused field.
329 i32, ;; DWARF language identifier (ex. DW_LANG_C89)
330 metadata, ;; Source file name
331 metadata, ;; Source file directory (includes trailing slash)
332 metadata ;; Producer (ex. "4.0.1 LLVM (LLVM research group)")
333 i1, ;; True if this is a main compile unit.
334 i1, ;; True if this is optimized.
335 metadata, ;; Flags
336 i32 ;; Runtime version
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]337}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]338</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]339</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]340
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]341<p>These descriptors contain a source language ID for the file (we use the DWARF
342 3.0 ID numbers, such as <tt>DW_LANG_C89</tt>, <tt>DW_LANG_C_plus_plus</tt>,
343 <tt>DW_LANG_Cobol74</tt>, etc), three strings describing the filename,
344 working directory of the compiler, and an identifier string for the compiler
345 that produced it.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]346
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]347<p>Compile unit descriptors provide the root context for objects declared in a
348 specific source file. Global variables and top level functions would be
349 defined using this context. Compile unit descriptors also provide context
350 for source line correspondence.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]351
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]352<p>Each input file is encoded as a separate compile unit in LLVM debugging
353 information output. However, many target specific tool chains prefer to
354 encode only one compile unit in an object file. In this situation, the LLVM
355 code generator will include debugging information entities in the compile
356 unit that is marked as main compile unit. The code generator accepts maximum
357 one main compile unit per module. If a module does not contain any main
358 compile unit then the code generator will emit multiple compile units in the
359 output object file.</p>
360
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]361</div>
362
363<!-- ======================================================================= -->
364<div class="doc_subsubsection">
365 <a name="format_global_variables">Global variable descriptors</a>
366</div>
367
368<div class="doc_text">
369
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]370<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]371<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]372!1 = metadata !{
373 i32, ;; Tag = 52 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
374 ;; (DW_TAG_variable)
375 i32, ;; Unused field.
376 metadata, ;; Reference to context descriptor
377 metadata, ;; Name
378 metadata, ;; Display name (fully qualified C++ name)
379 metadata, ;; MIPS linkage name (for C++)
380 metadata, ;; Reference to compile unit where defined
381 i32, ;; Line number where defined
382 metadata, ;; Reference to type descriptor
383 i1, ;; True if the global is local to compile unit (static)
384 i1, ;; True if the global is defined in the compile unit (not extern)
385 { }* ;; Reference to the global variable
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]386}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]387</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]388</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]389
390<p>These descriptors provide debug information about globals variables. The
391provide details such as name, type and where the variable is defined.</p>
392
393</div>
394
395<!-- ======================================================================= -->
396<div class="doc_subsubsection">
397 <a name="format_subprograms">Subprogram descriptors</a>
398</div>
399
400<div class="doc_text">
401
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]402<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]403<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]404!2 = metadata !{
405 i32, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
406 ;; (DW_TAG_subprogram)
407 i32, ;; Unused field.
408 metadata, ;; Reference to context descriptor
409 metadata, ;; Name
410 metadata, ;; Display name (fully qualified C++ name)
411 metadata, ;; MIPS linkage name (for C++)
412 metadata, ;; Reference to compile unit where defined
413 i32, ;; Line number where defined
414 metadata, ;; Reference to type descriptor
415 i1, ;; True if the global is local to compile unit (static)
416 i1 ;; True if the global is defined in the compile unit (not extern)
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]417}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]418</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]419</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]420
421<p>These descriptors provide debug information about functions, methods and
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]422 subprograms. They provide details such as name, return types and the source
423 location where the subprogram is defined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]424
425</div>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]426
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]427<!-- ======================================================================= -->
428<div class="doc_subsubsection">
429 <a name="format_blocks">Block descriptors</a>
430</div>
431
432<div class="doc_text">
433
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]434<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]435<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]436!3 = metadata !{
437 i32, ;; Tag = 13 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
438 metadata ;; Reference to context descriptor
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]439}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]440</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]441</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]442
443<p>These descriptors provide debug information about nested blocks within a
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]444 subprogram. The array of member descriptors is used to define local
445 variables and deeper nested blocks.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]446
447</div>
448
449<!-- ======================================================================= -->
450<div class="doc_subsubsection">
451 <a name="format_basic_type">Basic type descriptors</a>
452</div>
453
454<div class="doc_text">
455
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]456<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]457<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]458!4 = metadata !{
459 i32, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
460 ;; (DW_TAG_base_type)
461 metadata, ;; Reference to context (typically a compile unit)
462 metadata, ;; Name (may be "" for anonymous types)
463 metadata, ;; Reference to compile unit where defined (may be NULL)
464 i32, ;; Line number where defined (may be 0)
465 i64, ;; Size in bits
466 i64, ;; Alignment in bits
467 i64, ;; Offset in bits
468 i32, ;; Flags
469 i32 ;; DWARF type encoding
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]470}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]471</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]472</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]473
474<p>These descriptors define primitive types used in the code. Example int, bool
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]475 and float. The context provides the scope of the type, which is usually the
476 top level. Since basic types are not usually user defined the compile unit
477 and line number can be left as NULL and 0. The size, alignment and offset
478 are expressed in bits and can be 64 bit values. The alignment is used to
479 round the offset when embedded in a
480 <a href="#format_composite_type">composite type</a> (example to keep float
481 doubles on 64 bit boundaries.) The offset is the bit offset if embedded in
482 a <a href="#format_composite_type">composite type</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]483
484<p>The type encoding provides the details of the type. The values are typically
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]485 one of the following:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]486
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]487<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]488<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]489DW_ATE_address = 1
490DW_ATE_boolean = 2
491DW_ATE_float = 4
492DW_ATE_signed = 5
493DW_ATE_signed_char = 6
494DW_ATE_unsigned = 7
495DW_ATE_unsigned_char = 8
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]496</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]497</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]498
499</div>
500
501<!-- ======================================================================= -->
502<div class="doc_subsubsection">
503 <a name="format_derived_type">Derived type descriptors</a>
504</div>
505
506<div class="doc_text">
507
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]508<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]509<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]510!5 = metadata !{
511 i32, ;; Tag (see below)
512 metadata, ;; Reference to context
513 metadata, ;; Name (may be "" for anonymous types)
514 metadata, ;; Reference to compile unit where defined (may be NULL)
515 i32, ;; Line number where defined (may be 0)
516 i32, ;; Size in bits
517 i32, ;; Alignment in bits
518 i32, ;; Offset in bits
519 metadata ;; Reference to type derived from
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]520}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]521</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]522</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]523
524<p>These descriptors are used to define types derived from other types. The
525value of the tag varies depending on the meaning. The following are possible
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]526tag values:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]527
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]528<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]529<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]530DW_TAG_formal_parameter = 5
531DW_TAG_member = 13
532DW_TAG_pointer_type = 15
533DW_TAG_reference_type = 16
534DW_TAG_typedef = 22
535DW_TAG_const_type = 38
536DW_TAG_volatile_type = 53
537DW_TAG_restrict_type = 55
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]538</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]539</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]540
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]541<p><tt>DW_TAG_member</tt> is used to define a member of
542 a <a href="#format_composite_type">composite type</a>
543 or <a href="#format_subprograms">subprogram</a>. The type of the member is
544 the <a href="#format_derived_type">derived
545 type</a>. <tt>DW_TAG_formal_parameter</tt> is used to define a member which
546 is a formal argument of a subprogram.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]547
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]548<p><tt>DW_TAG_typedef</tt> is used to provide a name for the derived type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]549
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]550<p><tt>DW_TAG_pointer_type</tt>,<tt>DW_TAG_reference_type</tt>,
551 <tt>DW_TAG_const_type</tt>, <tt>DW_TAG_volatile_type</tt>
552 and <tt>DW_TAG_restrict_type</tt> are used to qualify
553 the <a href="#format_derived_type">derived type</a>. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]554
555<p><a href="#format_derived_type">Derived type</a> location can be determined
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]556 from the compile unit and line number. The size, alignment and offset are
557 expressed in bits and can be 64 bit values. The alignment is used to round
558 the offset when embedded in a <a href="#format_composite_type">composite
559 type</a> (example to keep float doubles on 64 bit boundaries.) The offset is
560 the bit offset if embedded in a <a href="#format_composite_type">composite
561 type</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]562
563<p>Note that the <tt>void *</tt> type is expressed as a
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]564 <tt>llvm.dbg.derivedtype.type</tt> with tag of <tt>DW_TAG_pointer_type</tt>
565 and <tt>NULL</tt> derived type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]566
567</div>
568
569<!-- ======================================================================= -->
570<div class="doc_subsubsection">
571 <a name="format_composite_type">Composite type descriptors</a>
572</div>
573
574<div class="doc_text">
575
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]576<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]577<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]578!6 = metadata !{
579 i32, ;; Tag (see below)
580 metadata, ;; Reference to context
581 metadata, ;; Name (may be "" for anonymous types)
582 metadata, ;; Reference to compile unit where defined (may be NULL)
583 i32, ;; Line number where defined (may be 0)
584 i64, ;; Size in bits
585 i64, ;; Alignment in bits
586 i64, ;; Offset in bits
587 i32, ;; Flags
588 metadata, ;; Reference to type derived from
589 metadata, ;; Reference to array of member descriptors
590 i32 ;; Runtime languages
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]591}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]592</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]593</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]594
595<p>These descriptors are used to define types that are composed of 0 or more
596elements. The value of the tag varies depending on the meaning. The following
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]597are possible tag values:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]598
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]599<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]600<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]601DW_TAG_array_type = 1
602DW_TAG_enumeration_type = 4
603DW_TAG_structure_type = 19
604DW_TAG_union_type = 23
605DW_TAG_vector_type = 259
Bruno Cardoso Lopes7ad46092009-05-29 17:08:57 +0000[diff] [blame]606DW_TAG_subroutine_type = 21
607DW_TAG_inheritance = 28
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]608</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]609</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]610
611<p>The vector flag indicates that an array type is a native packed vector.</p>
612
613<p>The members of array types (tag = <tt>DW_TAG_array_type</tt>) or vector types
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]614 (tag = <tt>DW_TAG_vector_type</tt>) are <a href="#format_subrange">subrange
615 descriptors</a>, each representing the range of subscripts at that level of
616 indexing.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]617
618<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]619 <a href="#format_enumeration">enumerator descriptors</a>, each representing
620 the definition of enumeration value for the set.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]621
622<p>The members of structure (tag = <tt>DW_TAG_structure_type</tt>) or union (tag
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]623 = <tt>DW_TAG_union_type</tt>) types are any one of
624 the <a href="#format_basic_type">basic</a>,
625 <a href="#format_derived_type">derived</a>
626 or <a href="#format_composite_type">composite</a> type descriptors, each
627 representing a field member of the structure or union.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]628
629<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]630 provide information about base classes, static members and member
631 functions. If a member is a <a href="#format_derived_type">derived type
632 descriptor</a> and has a tag of <tt>DW_TAG_inheritance</tt>, then the type
633 represents a base class. If the member of is
634 a <a href="#format_global_variables">global variable descriptor</a> then it
635 represents a static member. And, if the member is
636 a <a href="#format_subprograms">subprogram descriptor</a> then it represents
637 a member function. For static members and member
638 functions, <tt>getName()</tt> returns the members link or the C++ mangled
639 name. <tt>getDisplayName()</tt> the simplied version of the name.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]640
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]641<p>The first member of subroutine (tag = <tt>DW_TAG_subroutine_type</tt>) type
642 elements is the return type for the subroutine. The remaining elements are
643 the formal arguments to the subroutine.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]644
645<p><a href="#format_composite_type">Composite type</a> location can be
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]646 determined from the compile unit and line number. The size, alignment and
647 offset are expressed in bits and can be 64 bit values. The alignment is used
648 to round the offset when embedded in
649 a <a href="#format_composite_type">composite type</a> (as an example, to keep
650 float doubles on 64 bit boundaries.) The offset is the bit offset if embedded
651 in a <a href="#format_composite_type">composite type</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]652
653</div>
654
655<!-- ======================================================================= -->
656<div class="doc_subsubsection">
657 <a name="format_subrange">Subrange descriptors</a>
658</div>
659
660<div class="doc_text">
661
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]662<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]663<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]664%<a href="#format_subrange">llvm.dbg.subrange.type</a> = type {
665 i32, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
666 i64, ;; Low value
667 i64 ;; High value
668}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]669</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]670</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]671
672<p>These descriptors are used to define ranges of array subscripts for an array
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]673 <a href="#format_composite_type">composite type</a>. The low value defines
674 the lower bounds typically zero for C/C++. The high value is the upper
675 bounds. Values are 64 bit. High - low + 1 is the size of the array. If low
676 == high the array will be unbounded.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]677
678</div>
679
680<!-- ======================================================================= -->
681<div class="doc_subsubsection">
682 <a name="format_enumeration">Enumerator descriptors</a>
683</div>
684
685<div class="doc_text">
686
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]687<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]688<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]689!6 = metadata !{
690 i32, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
691 ;; (DW_TAG_enumerator)
692 metadata, ;; Name
693 i64 ;; Value
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]694}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]695</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]696</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]697
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]698<p>These descriptors are used to define members of an
699 enumeration <a href="#format_composite_type">composite type</a>, it
700 associates the name to the value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]701
702</div>
703
704<!-- ======================================================================= -->
705<div class="doc_subsubsection">
706 <a name="format_variables">Local variables</a>
707</div>
708
709<div class="doc_text">
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]710
711<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]712<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]713!7 = metadata !{
714 i32, ;; Tag (see below)
715 metadata, ;; Context
716 metadata, ;; Name
717 metadata, ;; Reference to compile unit where defined
718 i32, ;; Line number where defined
719 metadata ;; Type descriptor
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]720}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]721</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]722</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]723
724<p>These descriptors are used to define variables local to a sub program. The
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]725 value of the tag depends on the usage of the variable:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]726
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]727<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]728<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]729DW_TAG_auto_variable = 256
730DW_TAG_arg_variable = 257
731DW_TAG_return_variable = 258
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]732</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]733</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]734
735<p>An auto variable is any variable declared in the body of the function. An
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]736 argument variable is any variable that appears as a formal argument to the
737 function. A return variable is used to track the result of a function and
738 has no source correspondent.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]739
740<p>The context is either the subprogram or block where the variable is defined.
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]741 Name the source variable name. Compile unit and line indicate where the
742 variable was defined. Type descriptor defines the declared type of the
743 variable.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]744
745</div>
746
747<!-- ======================================================================= -->
748<div class="doc_subsection">
749 <a name="format_common_intrinsics">Debugger intrinsic functions</a>
750</div>
751
752<div class="doc_text">
753
754<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]755 provide debug information at various points in generated code.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]756
757</div>
758
759<!-- ======================================================================= -->
760<div class="doc_subsubsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]761 <a name="format_common_declare">llvm.dbg.declare</a>
762</div>
763
764<div class="doc_text">
765<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]766 void %<a href="#format_common_declare">llvm.dbg.declare</a>( { } *, metadata )
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]767</pre>
768
769<p>This intrinsic provides information about a local element (ex. variable.) The
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]770 first argument is the alloca for the variable, cast to a <tt>{ }*</tt>. The
771 second argument is
772 the <tt>%<a href="#format_variables">llvm.dbg.variable</a></tt> containing
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]773 the description of the variable. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]774
775</div>
776
777<!-- ======================================================================= -->
778<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]779 <a name="format_common_lifetime">Object lifetimes and scoping</a>
780</div>
781
782<div class="doc_text">
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]783<p>In many languages, the local variables in functions can have their lifetimes
784 or scopes limited to a subset of a function. In the C family of languages,
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]785 for example, variables are only live (readable and writable) within the
786 source block that they are defined in. In functional languages, values are
787 only readable after they have been defined. Though this is a very obvious
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]788 concept, it is non-trivial to model in LLVM, because it has no notion of
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]789 scoping in this sense, and does not want to be tied to a language's scoping
790 rules.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]791
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]792<p>In order to handle this, the LLVM debug format uses the metadata attached to
793 llvm instructions to encode line nuber and scoping information. Consider the
794 following C fragment, for example:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]795
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]796<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]797<pre>
7981. void foo() {
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]7992. int X = 21;
8003. int Y = 22;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8014. {
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]8025. int Z = 23;
8036. Z = X;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8047. }
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]8058. X = Y;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8069. }
807</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]808</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]809
810<p>Compiled to LLVM, this function would be represented like this:</p>
811
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]812<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]813<pre>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]814define void @foo() nounwind ssp {
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]815entry:
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame^]816 %X = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
817 %Y = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
818 %Z = alloca i32, align 4 ; &lt;i32*&gt; [#uses=3]
819 %0 = bitcast i32* %X to { }* ; &lt;{ }*&gt; [#uses=1]
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]820 call void @llvm.dbg.declare({ }* %0, metadata !0), !dbg !7
821 store i32 21, i32* %X, !dbg !8
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame^]822 %1 = bitcast i32* %Y to { }* ; &lt;{ }*&gt; [#uses=1]
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]823 call void @llvm.dbg.declare({ }* %1, metadata !9), !dbg !10
824 store i32 22, i32* %Y, !dbg !11
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame^]825 %2 = bitcast i32* %Z to { }* ; &lt;{ }*&gt; [#uses=1]
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]826 call void @llvm.dbg.declare({ }* %2, metadata !12), !dbg !14
827 store i32 23, i32* %Z, !dbg !15
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame^]828 %tmp = load i32* %X, !dbg !16 ; &lt;i32&gt; [#uses=1]
829 %tmp1 = load i32* %Y, !dbg !16 ; &lt;i32&gt; [#uses=1]
830 %add = add nsw i32 %tmp, %tmp1, !dbg !16 ; &lt;i32&gt; [#uses=1]
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]831 store i32 %add, i32* %Z, !dbg !16
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame^]832 %tmp2 = load i32* %Y, !dbg !17 ; &lt;i32&gt; [#uses=1]
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]833 store i32 %tmp2, i32* %X, !dbg !17
834 ret void, !dbg !18
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]835}
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]836
837declare void @llvm.dbg.declare({ }*, metadata) nounwind readnone
838
839!0 = metadata !{i32 459008, metadata !1, metadata !"X",
840 metadata !3, i32 2, metadata !6}; [ DW_TAG_auto_variable ]
841!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
842!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo", metadata !"foo",
843 metadata !"foo", metadata !3, i32 1, metadata !4,
844 i1 false, i1 true}; [DW_TAG_subprogram ]
845!3 = metadata !{i32 458769, i32 0, i32 12, metadata !"foo.c",
846 metadata !"/private/tmp", metadata !"clang 1.1", i1 true,
847 i1 false, metadata !"", i32 0}; [DW_TAG_compile_unit ]
848!4 = metadata !{i32 458773, metadata !3, metadata !"", null, i32 0, i64 0, i64 0,
849 i64 0, i32 0, null, metadata !5, i32 0}; [DW_TAG_subroutine_type ]
850!5 = metadata !{null}
851!6 = metadata !{i32 458788, metadata !3, metadata !"int", metadata !3, i32 0,
852 i64 32, i64 32, i64 0, i32 0, i32 5}; [DW_TAG_base_type ]
853!7 = metadata !{i32 2, i32 7, metadata !1, null}
854!8 = metadata !{i32 2, i32 3, metadata !1, null}
855!9 = metadata !{i32 459008, metadata !1, metadata !"Y", metadata !3, i32 3,
856 metadata !6}; [ DW_TAG_auto_variable ]
857!10 = metadata !{i32 3, i32 7, metadata !1, null}
858!11 = metadata !{i32 3, i32 3, metadata !1, null}
859!12 = metadata !{i32 459008, metadata !13, metadata !"Z", metadata !3, i32 5,
860 metadata !6}; [ DW_TAG_auto_variable ]
861!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
862!14 = metadata !{i32 5, i32 9, metadata !13, null}
863!15 = metadata !{i32 5, i32 5, metadata !13, null}
864!16 = metadata !{i32 6, i32 5, metadata !13, null}
865!17 = metadata !{i32 8, i32 3, metadata !1, null}
866!18 = metadata !{i32 9, i32 1, metadata !2, null}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]867</pre>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]868</div>
869
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]870<p>This example illustrates a few important details about LLVM debugging
871 information. In particular, it shows how the <tt>llvm.dbg.declare</tt>
872 intrinsic and location information, which are attached to an instruction,
873 are applied together to allow a debugger to analyze the relationship between
874 statements, variable definitions, and the code used to implement the
875 function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]876
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]877<div class="doc_code">
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame^]878<pre>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]879call void @llvm.dbg.declare({ }* %0, metadata !0), !dbg !7
880</pre>
881</div>
882
883<p>The first intrinsic
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]884 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]885 encodes debugging information for the variable <tt>X</tt>. The metadata
886 <tt>!dbg !7</tt> attached to the intrinsic provides scope information for the
887 variable <tt>X</tt>.</p>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]888
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]889<div class="doc_code">
890<pre>
891!7 = metadata !{i32 2, i32 7, metadata !1, null}
892!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
893!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo",
894 metadata !"foo", metadata !"foo", metadata !3, i32 1,
895 metadata !4, i1 false, i1 true}; [DW_TAG_subprogram ]
896</pre>
897</div>
898
899<p>Here <tt>!7</tt> is metadata providing location information. It has four
900 fields: line number, column number, scope, and original scope. The original
901 scope represents inline location if this instruction is inlined inside a
902 caller, and is null otherwise. In this example, scope is encoded by
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]903 <tt>!1</tt>. <tt>!1</tt> represents a lexical block inside the scope
904 <tt>!2</tt>, where <tt>!2</tt> is a
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]905 <a href="#format_subprograms">subprogram descriptor</a>. This way the
906 location information attached to the intrinsics indicates that the
907 variable <tt>X</tt> is declared at line number 2 at a function level scope in
908 function <tt>foo</tt>.</p>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]909
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]910<p>Now lets take another example.</p>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]911
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]912<div class="doc_code">
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame^]913<pre>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]914call void @llvm.dbg.declare({ }* %2, metadata !12), !dbg !14
915</pre>
916</div>
917
918<p>The second intrinsic
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]919 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]920 encodes debugging information for variable <tt>Z</tt>. The metadata
921 <tt>!dbg !14</tt> attached to the intrinsic provides scope information for
922 the variable <tt>Z</tt>.</p>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]923
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]924<div class="doc_code">
925<pre>
926!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
927!14 = metadata !{i32 5, i32 9, metadata !13, null}
928</pre>
929</div>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]930
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]931<p>Here <tt>!14</tt> indicates that <tt>Z</tt> is declaread at line number 5 and
932 column number 9 inside of lexical scope <tt>!13</tt>. The lexical scope
933 itself resides inside of lexical scope <tt>!1</tt> described above.</p>
934
935<p>The scope information attached with each instruction provides a
936 straightforward way to find instructions covered by a scope.</p>
937
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]938</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]939
940<!-- *********************************************************************** -->
941<div class="doc_section">
942 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
943</div>
944<!-- *********************************************************************** -->
945
946<div class="doc_text">
947
948<p>The C and C++ front-ends represent information about the program in a format
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]949 that is effectively identical
950 to <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3.0</a> in
951 terms of information content. This allows code generators to trivially
952 support native debuggers by generating standard dwarf information, and
953 contains enough information for non-dwarf targets to translate it as
954 needed.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]955
956<p>This section describes the forms used to represent C and C++ programs. Other
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]957 languages could pattern themselves after this (which itself is tuned to
958 representing programs in the same way that DWARF 3 does), or they could
959 choose to provide completely different forms if they don't fit into the DWARF
960 model. As support for debugging information gets added to the various LLVM
961 source-language front-ends, the information used should be documented
962 here.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]963
964<p>The following sections provide examples of various C/C++ constructs and the
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]965 debug information that would best describe those constructs.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]966
967</div>
968
969<!-- ======================================================================= -->
970<div class="doc_subsection">
971 <a name="ccxx_compile_units">C/C++ source file information</a>
972</div>
973
974<div class="doc_text">
975
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]976<p>Given the source files <tt>MySource.cpp</tt> and <tt>MyHeader.h</tt> located
977 in the directory <tt>/Users/mine/sources</tt>, the following code:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]978
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]979<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]980<pre>
981#include "MyHeader.h"
982
983int main(int argc, char *argv[]) {
984 return 0;
985}
986</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]987</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]988
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]989<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]990
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]991<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]992<pre>
993...
994;;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]995;; Define the compile unit for the source file "/Users/mine/sources/MySource.cpp".
996;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]997!3 = metadata !{
998 i32 458769, ;; Tag
999 i32 0, ;; Unused
1000 i32 4, ;; Language Id
1001 metadata !"MySource.cpp",
1002 metadata !"/Users/mine/sources",
1003 metadata !"4.2.1 (Based on Apple Inc. build 5649) (LLVM build 00)",
1004 i1 true, ;; Main Compile Unit
1005 i1 false, ;; Optimized compile unit
1006 metadata !"", ;; Compiler flags
1007 i32 0} ;; Runtime version
1008
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1009;;
1010;; Define the compile unit for the header file "/Users/mine/sources/MyHeader.h".
1011;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1012!1 = metadata !{
1013 i32 458769, ;; Tag
1014 i32 0, ;; Unused
1015 i32 4, ;; Language Id
1016 metadata !"MyHeader.h",
1017 metadata !"/Users/mine/sources",
1018 metadata !"4.2.1 (Based on Apple Inc. build 5649) (LLVM build 00)",
1019 i1 false, ;; Main Compile Unit
1020 i1 false, ;; Optimized compile unit
1021 metadata !"", ;; Compiler flags
1022 i32 0} ;; Runtime version
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1023
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1024...
1025</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1026</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1027
1028</div>
1029
1030<!-- ======================================================================= -->
1031<div class="doc_subsection">
1032 <a name="ccxx_global_variable">C/C++ global variable information</a>
1033</div>
1034
1035<div class="doc_text">
1036
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1037<p>Given an integer global variable declared as follows:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1038
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1039<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1040<pre>
1041int MyGlobal = 100;
1042</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1043</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1044
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1045<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1046
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1047<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1048<pre>
1049;;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1050;; Define the global itself.
1051;;
1052%MyGlobal = global int 100
1053...
1054;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1055;; List of debug info of globals
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1056;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1057!llvm.dbg.gv = !{!0}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1058
1059;;
1060;; Define the global variable descriptor. Note the reference to the global
1061;; variable anchor and the global variable itself.
1062;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1063!0 = metadata !{
1064 i32 458804, ;; Tag
1065 i32 0, ;; Unused
1066 metadata !1, ;; Context
1067 metadata !"MyGlobal", ;; Name
1068 metadata !"MyGlobal", ;; Display Name
1069 metadata !"MyGlobal", ;; Linkage Name
1070 metadata !1, ;; Compile Unit
1071 i32 1, ;; Line Number
1072 metadata !2, ;; Type
1073 i1 false, ;; Is a local variable
1074 i1 true, ;; Is this a definition
1075 i32* @MyGlobal ;; The global variable
1076}
1077
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1078;;
1079;; Define the basic type of 32 bit signed integer. Note that since int is an
1080;; intrinsic type the source file is NULL and line 0.
1081;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1082!2 = metadata !{
1083 i32 458788, ;; Tag
1084 metadata !1, ;; Context
1085 metadata !"int", ;; Name
1086 metadata !1, ;; Compile Unit
1087 i32 0, ;; Line number
1088 i64 32, ;; Size in Bits
1089 i64 32, ;; Align in Bits
1090 i64 0, ;; Offset in Bits
1091 i32 0, ;; Flags
1092 i32 5 ;; Encoding
1093}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1094
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1095</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1096</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1097
1098</div>
1099
1100<!-- ======================================================================= -->
1101<div class="doc_subsection">
1102 <a name="ccxx_subprogram">C/C++ function information</a>
1103</div>
1104
1105<div class="doc_text">
1106
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1107<p>Given a function declared as follows:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1108
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1109<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1110<pre>
1111int main(int argc, char *argv[]) {
1112 return 0;
1113}
1114</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1115</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1116
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1117<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1118
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1119<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1120<pre>
1121;;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1122;; Define the anchor for subprograms. Note that the second field of the
1123;; anchor is 46, which is the same as the tag for subprograms
1124;; (46 = DW_TAG_subprogram.)
1125;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1126!0 = metadata !{
1127 i32 458798, ;; Tag
1128 i32 0, ;; Unused
1129 metadata !1, ;; Context
1130 metadata !"main", ;; Name
1131 metadata !"main", ;; Display name
1132 metadata !"main", ;; Linkage name
1133 metadata !1, ;; Compile unit
1134 i32 1, ;; Line number
1135 metadata !2, ;; Type
1136 i1 false, ;; Is local
1137 i1 true ;; Is definition
1138}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1139;;
1140;; Define the subprogram itself.
1141;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1142define i32 @main(i32 %argc, i8** %argv) {
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1143...
1144}
1145</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1146</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1147
1148</div>
1149
1150<!-- ======================================================================= -->
1151<div class="doc_subsection">
1152 <a name="ccxx_basic_types">C/C++ basic types</a>
1153</div>
1154
1155<div class="doc_text">
1156
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1157<p>The following are the basic type descriptors for C/C++ core types:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1158
1159</div>
1160
1161<!-- ======================================================================= -->
1162<div class="doc_subsubsection">
1163 <a name="ccxx_basic_type_bool">bool</a>
1164</div>
1165
1166<div class="doc_text">
1167
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1168<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1169<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1170!2 = metadata !{
1171 i32 458788, ;; Tag
1172 metadata !1, ;; Context
1173 metadata !"bool", ;; Name
1174 metadata !1, ;; Compile Unit
1175 i32 0, ;; Line number
1176 i64 8, ;; Size in Bits
1177 i64 8, ;; Align in Bits
1178 i64 0, ;; Offset in Bits
1179 i32 0, ;; Flags
1180 i32 2 ;; Encoding
1181}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1182</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1183</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1184
1185</div>
1186
1187<!-- ======================================================================= -->
1188<div class="doc_subsubsection">
1189 <a name="ccxx_basic_char">char</a>
1190</div>
1191
1192<div class="doc_text">
1193
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1194<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1195<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1196!2 = metadata !{
1197 i32 458788, ;; Tag
1198 metadata !1, ;; Context
1199 metadata !"char", ;; Name
1200 metadata !1, ;; Compile Unit
1201 i32 0, ;; Line number
1202 i64 8, ;; Size in Bits
1203 i64 8, ;; Align in Bits
1204 i64 0, ;; Offset in Bits
1205 i32 0, ;; Flags
1206 i32 6 ;; Encoding
1207}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1208</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1209</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1210
1211</div>
1212
1213<!-- ======================================================================= -->
1214<div class="doc_subsubsection">
1215 <a name="ccxx_basic_unsigned_char">unsigned char</a>
1216</div>
1217
1218<div class="doc_text">
1219
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1220<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1221<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1222!2 = metadata !{
1223 i32 458788, ;; Tag
1224 metadata !1, ;; Context
1225 metadata !"unsigned char",
1226 metadata !1, ;; Compile Unit
1227 i32 0, ;; Line number
1228 i64 8, ;; Size in Bits
1229 i64 8, ;; Align in Bits
1230 i64 0, ;; Offset in Bits
1231 i32 0, ;; Flags
1232 i32 8 ;; Encoding
1233}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1234</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1235</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1236
1237</div>
1238
1239<!-- ======================================================================= -->
1240<div class="doc_subsubsection">
1241 <a name="ccxx_basic_short">short</a>
1242</div>
1243
1244<div class="doc_text">
1245
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1246<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1247<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1248!2 = metadata !{
1249 i32 458788, ;; Tag
1250 metadata !1, ;; Context
1251 metadata !"short int",
1252 metadata !1, ;; Compile Unit
1253 i32 0, ;; Line number
1254 i64 16, ;; Size in Bits
1255 i64 16, ;; Align in Bits
1256 i64 0, ;; Offset in Bits
1257 i32 0, ;; Flags
1258 i32 5 ;; Encoding
1259}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1260</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1261</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1262
1263</div>
1264
1265<!-- ======================================================================= -->
1266<div class="doc_subsubsection">
1267 <a name="ccxx_basic_unsigned_short">unsigned short</a>
1268</div>
1269
1270<div class="doc_text">
1271
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1272<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1273<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1274!2 = metadata !{
1275 i32 458788, ;; Tag
1276 metadata !1, ;; Context
1277 metadata !"short unsigned int",
1278 metadata !1, ;; Compile Unit
1279 i32 0, ;; Line number
1280 i64 16, ;; Size in Bits
1281 i64 16, ;; Align in Bits
1282 i64 0, ;; Offset in Bits
1283 i32 0, ;; Flags
1284 i32 7 ;; Encoding
1285}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1286</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1287</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1288
1289</div>
1290
1291<!-- ======================================================================= -->
1292<div class="doc_subsubsection">
1293 <a name="ccxx_basic_int">int</a>
1294</div>
1295
1296<div class="doc_text">
1297
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1298<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1299<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1300!2 = metadata !{
1301 i32 458788, ;; Tag
1302 metadata !1, ;; Context
1303 metadata !"int", ;; Name
1304 metadata !1, ;; Compile Unit
1305 i32 0, ;; Line number
1306 i64 32, ;; Size in Bits
1307 i64 32, ;; Align in Bits
1308 i64 0, ;; Offset in Bits
1309 i32 0, ;; Flags
1310 i32 5 ;; Encoding
1311}
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1312</pre></div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1313
1314</div>
1315
1316<!-- ======================================================================= -->
1317<div class="doc_subsubsection">
1318 <a name="ccxx_basic_unsigned_int">unsigned int</a>
1319</div>
1320
1321<div class="doc_text">
1322
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1323<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1324<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1325!2 = metadata !{
1326 i32 458788, ;; Tag
1327 metadata !1, ;; Context
1328 metadata !"unsigned int",
1329 metadata !1, ;; Compile Unit
1330 i32 0, ;; Line number
1331 i64 32, ;; Size in Bits
1332 i64 32, ;; Align in Bits
1333 i64 0, ;; Offset in Bits
1334 i32 0, ;; Flags
1335 i32 7 ;; Encoding
1336}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1337</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1338</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1339
1340</div>
1341
1342<!-- ======================================================================= -->
1343<div class="doc_subsubsection">
1344 <a name="ccxx_basic_long_long">long long</a>
1345</div>
1346
1347<div class="doc_text">
1348
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1349<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1350<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1351!2 = metadata !{
1352 i32 458788, ;; Tag
1353 metadata !1, ;; Context
1354 metadata !"long long int",
1355 metadata !1, ;; Compile Unit
1356 i32 0, ;; Line number
1357 i64 64, ;; Size in Bits
1358 i64 64, ;; Align in Bits
1359 i64 0, ;; Offset in Bits
1360 i32 0, ;; Flags
1361 i32 5 ;; Encoding
1362}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1363</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1364</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1365
1366</div>
1367
1368<!-- ======================================================================= -->
1369<div class="doc_subsubsection">
1370 <a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
1371</div>
1372
1373<div class="doc_text">
1374
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1375<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1376<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1377!2 = metadata !{
1378 i32 458788, ;; Tag
1379 metadata !1, ;; Context
1380 metadata !"long long unsigned int",
1381 metadata !1, ;; Compile Unit
1382 i32 0, ;; Line number
1383 i64 64, ;; Size in Bits
1384 i64 64, ;; Align in Bits
1385 i64 0, ;; Offset in Bits
1386 i32 0, ;; Flags
1387 i32 7 ;; Encoding
1388}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1389</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1390</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1391
1392</div>
1393
1394<!-- ======================================================================= -->
1395<div class="doc_subsubsection">
1396 <a name="ccxx_basic_float">float</a>
1397</div>
1398
1399<div class="doc_text">
1400
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1401<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1402<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1403!2 = metadata !{
1404 i32 458788, ;; Tag
1405 metadata !1, ;; Context
1406 metadata !"float",
1407 metadata !1, ;; Compile Unit
1408 i32 0, ;; Line number
1409 i64 32, ;; Size in Bits
1410 i64 32, ;; Align in Bits
1411 i64 0, ;; Offset in Bits
1412 i32 0, ;; Flags
1413 i32 4 ;; Encoding
1414}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1415</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1416</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1417
1418</div>
1419
1420<!-- ======================================================================= -->
1421<div class="doc_subsubsection">
1422 <a name="ccxx_basic_double">double</a>
1423</div>
1424
1425<div class="doc_text">
1426
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1427<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1428<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1429!2 = metadata !{
1430 i32 458788, ;; Tag
1431 metadata !1, ;; Context
1432 metadata !"double",;; Name
1433 metadata !1, ;; Compile Unit
1434 i32 0, ;; Line number
1435 i64 64, ;; Size in Bits
1436 i64 64, ;; Align in Bits
1437 i64 0, ;; Offset in Bits
1438 i32 0, ;; Flags
1439 i32 4 ;; Encoding
1440}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1441</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1442</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1443
1444</div>
1445
1446<!-- ======================================================================= -->
1447<div class="doc_subsection">
1448 <a name="ccxx_derived_types">C/C++ derived types</a>
1449</div>
1450
1451<div class="doc_text">
1452
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1453<p>Given the following as an example of C/C++ derived type:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1454
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1455<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1456<pre>
1457typedef const int *IntPtr;
1458</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1459</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1460
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1461<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1462
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1463<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1464<pre>
1465;;
1466;; Define the typedef "IntPtr".
1467;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1468!2 = metadata !{
1469 i32 458774, ;; Tag
1470 metadata !1, ;; Context
1471 metadata !"IntPtr", ;; Name
1472 metadata !3, ;; Compile unit
1473 i32 0, ;; Line number
1474 i64 0, ;; Size in bits
1475 i64 0, ;; Align in bits
1476 i64 0, ;; Offset in bits
1477 i32 0, ;; Flags
1478 metadata !4 ;; Derived From type
1479}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1480
1481;;
1482;; Define the pointer type.
1483;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1484!4 = metadata !{
1485 i32 458767, ;; Tag
1486 metadata !1, ;; Context
1487 metadata !"", ;; Name
1488 metadata !1, ;; Compile unit
1489 i32 0, ;; Line number
1490 i64 64, ;; Size in bits
1491 i64 64, ;; Align in bits
1492 i64 0, ;; Offset in bits
1493 i32 0, ;; Flags
1494 metadata !5 ;; Derived From type
1495}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1496;;
1497;; Define the const type.
1498;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1499!5 = metadata !{
1500 i32 458790, ;; Tag
1501 metadata !1, ;; Context
1502 metadata !"", ;; Name
1503 metadata !1, ;; Compile unit
1504 i32 0, ;; Line number
1505 i64 32, ;; Size in bits
1506 i64 32, ;; Align in bits
1507 i64 0, ;; Offset in bits
1508 i32 0, ;; Flags
1509 metadata !6 ;; Derived From type
1510}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1511;;
1512;; Define the int type.
1513;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1514!6 = metadata !{
1515 i32 458788, ;; Tag
1516 metadata !1, ;; Context
1517 metadata !"int", ;; Name
1518 metadata !1, ;; Compile unit
1519 i32 0, ;; Line number
1520 i64 32, ;; Size in bits
1521 i64 32, ;; Align in bits
1522 i64 0, ;; Offset in bits
1523 i32 0, ;; Flags
1524 5 ;; Encoding
1525}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1526</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1527</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1528
1529</div>
1530
1531<!-- ======================================================================= -->
1532<div class="doc_subsection">
1533 <a name="ccxx_composite_types">C/C++ struct/union types</a>
1534</div>
1535
1536<div class="doc_text">
1537
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1538<p>Given the following as an example of C/C++ struct type:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1539
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1540<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1541<pre>
1542struct Color {
1543 unsigned Red;
1544 unsigned Green;
1545 unsigned Blue;
1546};
1547</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1548</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1549
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1550<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1551
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1552<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1553<pre>
1554;;
1555;; Define basic type for unsigned int.
1556;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1557!5 = metadata !{
1558 i32 458788, ;; Tag
1559 metadata !1, ;; Context
1560 metadata !"unsigned int",
1561 metadata !1, ;; Compile Unit
1562 i32 0, ;; Line number
1563 i64 32, ;; Size in Bits
1564 i64 32, ;; Align in Bits
1565 i64 0, ;; Offset in Bits
1566 i32 0, ;; Flags
1567 i32 7 ;; Encoding
1568}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1569;;
1570;; Define composite type for struct Color.
1571;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1572!2 = metadata !{
1573 i32 458771, ;; Tag
1574 metadata !1, ;; Context
1575 metadata !"Color", ;; Name
1576 metadata !1, ;; Compile unit
1577 i32 1, ;; Line number
1578 i64 96, ;; Size in bits
1579 i64 32, ;; Align in bits
1580 i64 0, ;; Offset in bits
1581 i32 0, ;; Flags
1582 null, ;; Derived From
1583 metadata !3, ;; Elements
1584 i32 0 ;; Runtime Language
1585}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1586
1587;;
1588;; Define the Red field.
1589;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1590!4 = metadata !{
1591 i32 458765, ;; Tag
1592 metadata !1, ;; Context
1593 metadata !"Red", ;; Name
1594 metadata !1, ;; Compile Unit
1595 i32 2, ;; Line number
1596 i64 32, ;; Size in bits
1597 i64 32, ;; Align in bits
1598 i64 0, ;; Offset in bits
1599 i32 0, ;; Flags
1600 metadata !5 ;; Derived From type
1601}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1602
1603;;
1604;; Define the Green field.
1605;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1606!6 = metadata !{
1607 i32 458765, ;; Tag
1608 metadata !1, ;; Context
1609 metadata !"Green", ;; Name
1610 metadata !1, ;; Compile Unit
1611 i32 3, ;; Line number
1612 i64 32, ;; Size in bits
1613 i64 32, ;; Align in bits
1614 i64 32, ;; Offset in bits
1615 i32 0, ;; Flags
1616 metadata !5 ;; Derived From type
1617}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1618
1619;;
1620;; Define the Blue field.
1621;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1622!7 = metadata !{
1623 i32 458765, ;; Tag
1624 metadata !1, ;; Context
1625 metadata !"Blue", ;; Name
1626 metadata !1, ;; Compile Unit
1627 i32 4, ;; Line number
1628 i64 32, ;; Size in bits
1629 i64 32, ;; Align in bits
1630 i64 64, ;; Offset in bits
1631 i32 0, ;; Flags
1632 metadata !5 ;; Derived From type
1633}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1634
1635;;
1636;; Define the array of fields used by the composite type Color.
1637;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1638!3 = metadata !{metadata !4, metadata !6, metadata !7}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1639</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1640</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1641
1642</div>
1643
1644<!-- ======================================================================= -->
1645<div class="doc_subsection">
1646 <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
1647</div>
1648
1649<div class="doc_text">
1650
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1651<p>Given the following as an example of C/C++ enumeration type:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1652
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1653<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1654<pre>
1655enum Trees {
1656 Spruce = 100,
1657 Oak = 200,
1658 Maple = 300
1659};
1660</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1661</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1662
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1663<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1664
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1665<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1666<pre>
1667;;
1668;; Define composite type for enum Trees
1669;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1670!2 = metadata !{
1671 i32 458756, ;; Tag
1672 metadata !1, ;; Context
1673 metadata !"Trees", ;; Name
1674 metadata !1, ;; Compile unit
1675 i32 1, ;; Line number
1676 i64 32, ;; Size in bits
1677 i64 32, ;; Align in bits
1678 i64 0, ;; Offset in bits
1679 i32 0, ;; Flags
1680 null, ;; Derived From type
1681 metadata !3, ;; Elements
1682 i32 0 ;; Runtime language
1683}
Devang Patel57b83c72009-08-25 05:24:07 +0000[diff] [blame]1684
Devang Patel94060422009-08-26 05:01:18 +0000[diff] [blame]1685;;
1686;; Define the array of enumerators used by composite type Trees.
1687;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1688!3 = metadata !{metadata !4, metadata !5, metadata !6}
1689
1690;;
1691;; Define Spruce enumerator.
1692;;
1693!4 = metadata !{i32 458792, metadata !"Spruce", i64 100}
1694
1695;;
1696;; Define Oak enumerator.
1697;;
1698!5 = metadata !{i32 458792, metadata !"Oak", i64 200}
1699
1700;;
1701;; Define Maple enumerator.
1702;;
1703!6 = metadata !{i32 458792, metadata !"Maple", i64 300}
1704
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1705</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1706</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1707
1708</div>
1709
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1711
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