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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / c500566d9fb70472a17f62b4cf1689062c52e095 / . / docs / SourceLevelDebugging.html
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Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]6 <title>Source Level Debugging with LLVM</title>
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9<body>
10
11<div class="doc_title">Source Level Debugging with LLVM</div>
12
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]13<table class="layout" style="width:100%">
14 <tr class="layout">
15 <td class="left">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]16<ul>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]17 <li><a href="#introduction">Introduction</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]18 <ol>
19 <li><a href="#phil">Philosophy behind LLVM debugging information</a></li>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]20 <li><a href="#consumers">Debug information consumers</a></li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]21 <li><a href="#debugopt">Debugging optimized code</a></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]22 </ol></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]23 <li><a href="#format">Debugging information format</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]24 <ol>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]25 <li><a href="#debug_info_descriptors">Debug information descriptors</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]26 <ul>
Jim Laskeycec12a52006-03-14 18:08:46 +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>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]30 <li><a href="#format_blocks">Block descriptors</a></li>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]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>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]36 <li><a href="#format_variables">Local variables</a></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]37 </ul></li>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]38 <li><a href="#format_common_intrinsics">Debugger intrinsic functions</a>
39 <ul>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]40 <li><a href="#format_common_declare">llvm.dbg.declare</a></li>
41 </ul></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]42 </ol></li>
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]43 <li><a href="#format_common_lifetime">Object lifetimes and scoping</a></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]44 <li><a href="#ccxx_frontend">C/C++ front-end specific debug information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]45 <ol>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]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>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]53 </ol></li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]54</ul>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]55</td>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]56<td class="right">
Misha Brukmane849a1a2004-05-12 21:26:16 +0000[diff] [blame]57<img src="img/venusflytrap.jpg" alt="A leafy and green bug eater" width="247"
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]58height="369">
59</td>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]60</tr></table>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]61
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]62<div class="doc_author">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]63 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
Jim Laskeyc760a922007-03-14 19:32:21 +0000[diff] [blame]64 and <a href="mailto:jlaskey@mac.com">Jim Laskey</a></p>
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]65</div>
66
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]67
68<!-- *********************************************************************** -->
Misha Brukman94218a72004-12-09 20:27:37 +0000[diff] [blame]69<div class="doc_section"><a name="introduction">Introduction</a></div>
70<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]71
72<div class="doc_text">
73
74<p>This document is the central repository for all information pertaining to
Bill Wendling48839d92009-05-17 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 Lattner8ad2f982009-07-18 21:47:15 +0000[diff] [blame]78 Further, this document provides specific examples of what debug information
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]79 for C/C++.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +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
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]90<p>The idea of the LLVM debugging information is to capture how the important
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]94
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]95<ul>
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]99
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]102
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]106
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]110
Bill Wendling48839d92009-05-17 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>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]115</ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]116
Bill Wendling48839d92009-05-17 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 Patele4b27562009-08-28 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 Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]125
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]126<p>When a program is being debugged, a debugger interacts with the user and
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]130
131</div>
132
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]133<!-- ======================================================================= -->
134<div class="doc_subsection">
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]135 <a name="consumers">Debug information consumers</a>
136</div>
137
138<div class="doc_text">
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]139
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]140<p>The role of debug information is to provide meta information normally
Bill Wendling48839d92009-05-17 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>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]144
145<p>Currently, debug information is consumed by the DwarfWriter to produce dwarf
Bill Wendling48839d92009-05-17 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>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]148
149<p>It would also be reasonable to use debug information to feed profiling tools
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]150 for analysis of generated code, or, tools for reconstructing the original
151 source from generated code.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]152
153<p>TODO - expound a bit more.</p>
154
155</div>
156
157<!-- ======================================================================= -->
158<div class="doc_subsection">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]159 <a name="debugopt">Debugging optimized code</a>
160</div>
161
162<div class="doc_text">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]163
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]164<p>An extremely high priority of LLVM debugging information is to make it
Bill Wendling48839d92009-05-17 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>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]167
168<ul>
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]176
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]182
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]188
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]193
Bill Wendling48839d92009-05-17 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>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]198</ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]199
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]200<p>Basically, the debug information allows you to compile a program with
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]208
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]209<p><a href="TestingGuide.html#quicktestsuite">LLVM test suite</a> provides a
Bill Wendling48839d92009-05-17 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 Patela5c05aa2008-11-21 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 Wendling48839d92009-05-17 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 Patela5c05aa2008-11-21 19:35:57 +0000[diff] [blame]224
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]225</div>
226
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]227<!-- *********************************************************************** -->
228<div class="doc_section">
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]229 <a name="format">Debugging information format</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]230</div>
231<!-- *********************************************************************** -->
232
233<div class="doc_text">
234
235<p>LLVM debugging information has been carefully designed to make it possible
Bill Wendling48839d92009-05-17 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 Patele4b27562009-08-28 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]242
243<p>To do this, most of the debugging information (descriptors for types,
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]244 variables, functions, source files, etc) is inserted by the language
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]245 front-end in the form of LLVM metadata. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]246
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]247<p>Debug information is designed to be agnostic about the target debugger and
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]248 debugging information representation (e.g. DWARF/Stabs/etc). It uses a
Devang Patele4b27562009-08-28 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]253
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]254<p>To provide basic functionality, the LLVM debugger does have to make some
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]261
262<p>This section of the documentation first describes the representation aspects
Bill Wendling48839d92009-05-17 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]265
266</div>
267
268<!-- ======================================================================= -->
269<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]270 <a name="debug_info_descriptors">Debug information descriptors</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]271</div>
272
273<div class="doc_text">
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]274
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]275<p>In consideration of the complexity and volume of debug information, LLVM
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]276 provides a specification for well formed debug descriptors. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]277
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]278<p>Consumers of LLVM debug information expect the descriptors for program
Bill Wendling48839d92009-05-17 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 Kramer8040cd32009-10-12 14:46:08 +0000[diff] [blame]286 the range 0x1000 through 0x2000 (there is a defined enum DW_TAG_user_base =
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]287 0x1000.)</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]288
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]289<p>The fields of debug descriptors used internally by LLVM
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]290 are restricted to only the simple data types <tt>int</tt>, <tt>uint</tt>,
Devang Patele4b27562009-08-28 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>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]293
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]294<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]295<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]296!1 = metadata !{
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]297 uint, ;; A tag
298 ...
299}
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]300</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]301</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]302
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]303<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
Bill Wendling48839d92009-05-17 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 Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]309 with the current debug version (LLVMDebugVersion = 7 << 16 or 0x70000 or
310 458752.)</a></p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]311
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]312<p>The details of the various descriptors follow.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]313
314</div>
315
316<!-- ======================================================================= -->
317<div class="doc_subsubsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]318 <a name="format_compile_units">Compile unit descriptors</a>
319</div>
320
321<div class="doc_text">
322
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]323<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]324<pre>
Devang Patele4b27562009-08-28 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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]337}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]338</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]339</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]340
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]346
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]351
Bill Wendling48839d92009-05-17 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
Jim Laskeycec12a52006-03-14 18:08:46 +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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]370<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]371<pre>
Devang Patele4b27562009-08-28 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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]386}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]387</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]388</div>
Jim Laskeycec12a52006-03-14 18:08:46 +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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]402<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]403<pre>
Devang Patele4b27562009-08-28 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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]417}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]418</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]419</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]420
421<p>These descriptors provide debug information about functions, methods and
Bill Wendling48839d92009-05-17 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>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]424
425</div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]426
Jim Laskey3d11bee2006-03-15 19:10:52 +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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]434<div class="doc_code">
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]435<pre>
Devang Patele4b27562009-08-28 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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]439}
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]440</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]441</div>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]442
443<p>These descriptors provide debug information about nested blocks within a
Bill Wendling48839d92009-05-17 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>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]446
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]456<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]457<pre>
Devang Patele4b27562009-08-28 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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]470}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]471</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]472</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]473
474<p>These descriptors define primitive types used in the code. Example int, bool
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]483
484<p>The type encoding provides the details of the type. The values are typically
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]485 one of the following:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]486
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]487<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]488<pre>
Bill Wendling48839d92009-05-17 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
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]496</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]497</div>
Jim Laskeycec12a52006-03-14 18:08:46 +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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]508<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]509<pre>
Devang Patele4b27562009-08-28 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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]520}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]521</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]522</div>
Jim Laskeycec12a52006-03-14 18:08:46 +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 Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]526tag values:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]527
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]528<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]529<pre>
Bill Wendling48839d92009-05-17 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
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]538</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]539</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]540
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]547
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]548<p><tt>DW_TAG_typedef</tt> is used to provide a name for the derived type.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]549
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]554
555<p><a href="#format_derived_type">Derived type</a> location can be determined
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]562
563<p>Note that the <tt>void *</tt> type is expressed as a
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]576<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]577<pre>
Devang Patele4b27562009-08-28 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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]591}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]592</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]593</div>
Jim Laskeycec12a52006-03-14 18:08:46 +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 Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]597are possible tag values:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]598
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]599<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]600<pre>
Bill Wendling48839d92009-05-17 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 Lopesd80ddc02009-05-29 17:08:57 +0000[diff] [blame]606DW_TAG_subroutine_type = 21
607DW_TAG_inheritance = 28
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]608</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]609</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]610
Jim Laskeyf8a01a92006-06-15 20:51:43 +0000[diff] [blame]611<p>The vector flag indicates that an array type is a native packed vector.</p>
612
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]613<p>The members of array types (tag = <tt>DW_TAG_array_type</tt>) or vector types
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]617
618<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]621
622<p>The members of structure (tag = <tt>DW_TAG_structure_type</tt>) or union (tag
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]628
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]629<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
Bill Wendling48839d92009-05-17 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>
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]640
Bill Wendling48839d92009-05-17 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>
Jim Laskey094ee722006-06-20 21:13:20 +0000[diff] [blame]644
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]645<p><a href="#format_composite_type">Composite type</a> location can be
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]662<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]663<pre>
Bill Wendling48839d92009-05-17 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}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]669</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]670</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]671
672<p>These descriptors are used to define ranges of array subscripts for an array
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]687<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]688<pre>
Devang Patele4b27562009-08-28 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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]694}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]695</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]696</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]697
Bill Wendling48839d92009-05-17 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>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]701
702</div>
703
704<!-- ======================================================================= -->
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]705<div class="doc_subsubsection">
706 <a name="format_variables">Local variables</a>
707</div>
708
709<div class="doc_text">
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]710
711<div class="doc_code">
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]712<pre>
Devang Patele4b27562009-08-28 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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]720}
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]721</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]722</div>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]723
724<p>These descriptors are used to define variables local to a sub program. The
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]725 value of the tag depends on the usage of the variable:</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]726
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]727<div class="doc_code">
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]728<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]729DW_TAG_auto_variable = 256
730DW_TAG_arg_variable = 257
731DW_TAG_return_variable = 258
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]732</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]733</div>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]734
735<p>An auto variable is any variable declared in the body of the function. An
Bill Wendling48839d92009-05-17 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>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]739
Jim Laskey2d395d92006-03-24 09:20:27 +0000[diff] [blame]740<p>The context is either the subprogram or block where the variable is defined.
Bill Wendling48839d92009-05-17 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>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]744
745</div>
746
747<!-- ======================================================================= -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]748<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]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 Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]755 provide debug information at various points in generated code.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]756
757</div>
758
759<!-- ======================================================================= -->
760<div class="doc_subsubsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]761 <a name="format_common_declare">llvm.dbg.declare</a>
762</div>
763
764<div class="doc_text">
765<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]766 void %<a href="#format_common_declare">llvm.dbg.declare</a>( { } *, metadata )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]767</pre>
768
Jim Laskey2d395d92006-03-24 09:20:27 +0000[diff] [blame]769<p>This intrinsic provides information about a local element (ex. variable.) The
Bill Wendling48839d92009-05-17 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 Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]773 the description of the variable. </p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]774
775</div>
776
777<!-- ======================================================================= -->
778<div class="doc_subsection">
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]779 <a name="format_common_lifetime">Object lifetimes and scoping</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]780</div>
781
782<div class="doc_text">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]783<p>In many languages, the local variables in functions can have their lifetime
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]784 or scope limited to a subset of a function. In the C family of languages,
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
788 concept, it is also non-trivial to model in LLVM, because it has no notion of
789 scoping in this sense, and does not want to be tied to a language's scoping
790 rules.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]791
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]792<p>In order to handle this, the LLVM debug format uses the metadata attached
793 with llvm instructions to encode line nuber and scoping information.
794 Consider the following C fragment, for example:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]795
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]796<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]797<pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]7981. void foo() {
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]7992. int X = 21;
8003. int Y = 22;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8014. {
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]8025. int Z = 23;
8036. Z = X;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8047. }
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]8058. X = Y;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8069. }
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]807</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]808</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]809
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]810<p>Compiled to LLVM, this function would be represented like this:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]811
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]812<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]813<pre>
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]814nounwind ssp {
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]815entry:
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]816 %X = alloca i32, align 4 ; <i32*> [#uses=4]
817 %Y = alloca i32, align 4 ; <i32*> [#uses=4]
818 %Z = alloca i32, align 4 ; <i32*> [#uses=3]
819 %0 = bitcast i32* %X to { }* ; <{ }*> [#uses=1]
820 call void @llvm.dbg.declare({ }* %0, metadata !0), !dbg !7
821 store i32 21, i32* %X, !dbg !8
822 %1 = bitcast i32* %Y to { }* ; <{ }*> [#uses=1]
823 call void @llvm.dbg.declare({ }* %1, metadata !9), !dbg !10
824 store i32 22, i32* %Y, !dbg !11
825 %2 = bitcast i32* %Z to { }* ; <{ }*> [#uses=1]
826 call void @llvm.dbg.declare({ }* %2, metadata !12), !dbg !14
827 store i32 23, i32* %Z, !dbg !15
828 %tmp = load i32* %X, !dbg !16 ; <i32> [#uses=1]
829 %tmp1 = load i32* %Y, !dbg !16 ; <i32> [#uses=1]
830 %add = add nsw i32 %tmp, %tmp1, !dbg !16 ; <i32> [#uses=1]
831 store i32 %add, i32* %Z, !dbg !16
832 %tmp2 = load i32* %Y, !dbg !17 ; <i32> [#uses=1]
833 store i32 %tmp2, i32* %X, !dbg !17
834 ret void, !dbg !18
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]835}
Devang Patel744950d2009-11-25 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}
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]867</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]868</div>
869
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]870<p>This example illustrates a few important details about the LLVM debugging
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]871 information. In particular, it shows how the llvm.dbg.declare intrinsic
872 and location information, attached with an instruction, are applied
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]873 together to allow a debugger to analyze the relationship between statements,
874 variable definitions, and the code used to implement the function.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]875
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]876 <div class="doc_code">
877 <pre>
878 call void @llvm.dbg.declare({ }* %0, metadata !0), !dbg !7
879 </pre>
880 </div>
881<p>This first intrinsic
882 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
883 encodes debugging information for variable <tt>X</tt>. The metadata,
884 <tt>!dbg !7</tt> attached with the intrinsic provides scope information for
885 the variable <tt>X</tt>. </p>
886 <div class="doc_code">
887 <pre>
888 !7 = metadata !{i32 2, i32 7, metadata !1, null}
889 !1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
890 !2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo",
891 metadata !"foo", metadata !"foo", metadata !3, i32 1,
892 metadata !4, i1 false, i1 true}; [DW_TAG_subprogram ]
893 </pre>
894 </div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]895
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]896<p> Here <tt>!7</tt> is a metadata providing location information. It has four
897 fields : line number, column number, scope and original scope. The original
898 scope represents inline location if this instruction is inlined inside
899 a caller. It is null otherwise. In this example scope is encoded by
900 <tt>!1</tt>. <tt>!1</tt> represents a lexical block inside the scope
901 <tt>!2</tt>, where <tt>!2</tt> is a
902 <a href="#format_subprograms">subprogram descriptor</a>.
903 This way the location information attched with the intrinsics indicates
904 that the variable <tt>X</tt> is declared at line number 2 at a function level
905 scope in function <tt>foo</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]906
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]907<p>Now lets take another example.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]908
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]909 <div class="doc_code">
910 <pre>
911 call void @llvm.dbg.declare({ }* %2, metadata !12), !dbg !14
912 </pre>
913 </div>
914<p>This intrinsic
915 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
916 encodes debugging information for variable <tt>Z</tt>. The metadata,
917 <tt>!dbg !14</tt> attached with the intrinsic provides scope information for
918 the variable <tt>Z</tt>. </p>
919 <div class="doc_code">
920 <pre>
921 !13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
922 !14 = metadata !{i32 5, i32 9, metadata !13, null}
923 </pre>
924 </div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]925
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]926<p> Here <tt>!14</tt> indicates that <tt>Z</tt> is declaread at line number 5,
927 column number 9 inside a lexical scope <tt>!13</tt>. This lexical scope
928 itself resides inside lexcial scope <tt>!1</tt> described above.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]929
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]930<p>The scope information attached with each instruction provides a straight
931 forward way to find instructions covered by a scope. </p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]932</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]933
934<!-- *********************************************************************** -->
935<div class="doc_section">
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]936 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]937</div>
Misha Brukman94218a72004-12-09 20:27:37 +0000[diff] [blame]938<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]939
940<div class="doc_text">
941
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]942<p>The C and C++ front-ends represent information about the program in a format
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]943 that is effectively identical
944 to <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3.0</a> in
945 terms of information content. This allows code generators to trivially
946 support native debuggers by generating standard dwarf information, and
947 contains enough information for non-dwarf targets to translate it as
948 needed.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]949
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]950<p>This section describes the forms used to represent C and C++ programs. Other
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]951 languages could pattern themselves after this (which itself is tuned to
952 representing programs in the same way that DWARF 3 does), or they could
953 choose to provide completely different forms if they don't fit into the DWARF
954 model. As support for debugging information gets added to the various LLVM
955 source-language front-ends, the information used should be documented
956 here.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]957
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]958<p>The following sections provide examples of various C/C++ constructs and the
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]959 debug information that would best describe those constructs.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]960
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]961</div>
962
963<!-- ======================================================================= -->
964<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]965 <a name="ccxx_compile_units">C/C++ source file information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]966</div>
967
968<div class="doc_text">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]969
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]970<p>Given the source files <tt>MySource.cpp</tt> and <tt>MyHeader.h</tt> located
971 in the directory <tt>/Users/mine/sources</tt>, the following code:</p>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]972
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]973<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]974<pre>
975#include "MyHeader.h"
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]976
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]977int main(int argc, char *argv[]) {
978 return 0;
979}
980</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]981</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]982
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]983<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]984
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]985<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]986<pre>
987...
988;;
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]989;; Define the compile unit for the source file "/Users/mine/sources/MySource.cpp".
990;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]991!3 = metadata !{
992 i32 458769, ;; Tag
993 i32 0, ;; Unused
994 i32 4, ;; Language Id
995 metadata !"MySource.cpp",
996 metadata !"/Users/mine/sources",
997 metadata !"4.2.1 (Based on Apple Inc. build 5649) (LLVM build 00)",
998 i1 true, ;; Main Compile Unit
999 i1 false, ;; Optimized compile unit
1000 metadata !"", ;; Compiler flags
1001 i32 0} ;; Runtime version
1002
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1003;;
1004;; Define the compile unit for the header file "/Users/mine/sources/MyHeader.h".
1005;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1006!1 = metadata !{
1007 i32 458769, ;; Tag
1008 i32 0, ;; Unused
1009 i32 4, ;; Language Id
1010 metadata !"MyHeader.h",
1011 metadata !"/Users/mine/sources",
1012 metadata !"4.2.1 (Based on Apple Inc. build 5649) (LLVM build 00)",
1013 i1 false, ;; Main Compile Unit
1014 i1 false, ;; Optimized compile unit
1015 metadata !"", ;; Compiler flags
1016 i32 0} ;; Runtime version
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1017
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1018...
1019</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1020</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1021
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1022</div>
1023
1024<!-- ======================================================================= -->
1025<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1026 <a name="ccxx_global_variable">C/C++ global variable information</a>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1027</div>
1028
1029<div class="doc_text">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1030
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1031<p>Given an integer global variable declared as follows:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1032
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1033<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1034<pre>
1035int MyGlobal = 100;
1036</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1037</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1038
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1039<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1040
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1041<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1042<pre>
1043;;
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1044;; Define the global itself.
1045;;
1046%MyGlobal = global int 100
1047...
1048;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1049;; List of debug info of globals
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1050;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1051!llvm.dbg.gv = !{!0}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1052
1053;;
1054;; Define the global variable descriptor. Note the reference to the global
1055;; variable anchor and the global variable itself.
1056;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1057!0 = metadata !{
1058 i32 458804, ;; Tag
1059 i32 0, ;; Unused
1060 metadata !1, ;; Context
1061 metadata !"MyGlobal", ;; Name
1062 metadata !"MyGlobal", ;; Display Name
1063 metadata !"MyGlobal", ;; Linkage Name
1064 metadata !1, ;; Compile Unit
1065 i32 1, ;; Line Number
1066 metadata !2, ;; Type
1067 i1 false, ;; Is a local variable
1068 i1 true, ;; Is this a definition
1069 i32* @MyGlobal ;; The global variable
1070}
1071
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1072;;
1073;; Define the basic type of 32 bit signed integer. Note that since int is an
1074;; intrinsic type the source file is NULL and line 0.
1075;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1076!2 = metadata !{
1077 i32 458788, ;; Tag
1078 metadata !1, ;; Context
1079 metadata !"int", ;; Name
1080 metadata !1, ;; Compile Unit
1081 i32 0, ;; Line number
1082 i64 32, ;; Size in Bits
1083 i64 32, ;; Align in Bits
1084 i64 0, ;; Offset in Bits
1085 i32 0, ;; Flags
1086 i32 5 ;; Encoding
1087}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1088
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1089</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1090</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1091
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1092</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1093
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1094<!-- ======================================================================= -->
1095<div class="doc_subsection">
1096 <a name="ccxx_subprogram">C/C++ function information</a>
1097</div>
1098
1099<div class="doc_text">
1100
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1101<p>Given a function declared as follows:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1102
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1103<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1104<pre>
1105int main(int argc, char *argv[]) {
1106 return 0;
1107}
1108</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1109</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1110
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1111<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1112
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1113<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1114<pre>
1115;;
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1116;; Define the anchor for subprograms. Note that the second field of the
1117;; anchor is 46, which is the same as the tag for subprograms
1118;; (46 = DW_TAG_subprogram.)
1119;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1120!0 = metadata !{
1121 i32 458798, ;; Tag
1122 i32 0, ;; Unused
1123 metadata !1, ;; Context
1124 metadata !"main", ;; Name
1125 metadata !"main", ;; Display name
1126 metadata !"main", ;; Linkage name
1127 metadata !1, ;; Compile unit
1128 i32 1, ;; Line number
1129 metadata !2, ;; Type
1130 i1 false, ;; Is local
1131 i1 true ;; Is definition
1132}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1133;;
1134;; Define the subprogram itself.
1135;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1136define i32 @main(i32 %argc, i8** %argv) {
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1137...
1138}
1139</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1140</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1141
1142</div>
1143
1144<!-- ======================================================================= -->
1145<div class="doc_subsection">
1146 <a name="ccxx_basic_types">C/C++ basic types</a>
1147</div>
1148
1149<div class="doc_text">
1150
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1151<p>The following are the basic type descriptors for C/C++ core types:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1152
1153</div>
1154
1155<!-- ======================================================================= -->
1156<div class="doc_subsubsection">
1157 <a name="ccxx_basic_type_bool">bool</a>
1158</div>
1159
1160<div class="doc_text">
1161
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1162<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1163<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1164!2 = metadata !{
1165 i32 458788, ;; Tag
1166 metadata !1, ;; Context
1167 metadata !"bool", ;; Name
1168 metadata !1, ;; Compile Unit
1169 i32 0, ;; Line number
1170 i64 8, ;; Size in Bits
1171 i64 8, ;; Align in Bits
1172 i64 0, ;; Offset in Bits
1173 i32 0, ;; Flags
1174 i32 2 ;; Encoding
1175}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1176</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1177</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1178
1179</div>
1180
1181<!-- ======================================================================= -->
1182<div class="doc_subsubsection">
1183 <a name="ccxx_basic_char">char</a>
1184</div>
1185
1186<div class="doc_text">
1187
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1188<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1189<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1190!2 = metadata !{
1191 i32 458788, ;; Tag
1192 metadata !1, ;; Context
1193 metadata !"char", ;; Name
1194 metadata !1, ;; Compile Unit
1195 i32 0, ;; Line number
1196 i64 8, ;; Size in Bits
1197 i64 8, ;; Align in Bits
1198 i64 0, ;; Offset in Bits
1199 i32 0, ;; Flags
1200 i32 6 ;; Encoding
1201}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1202</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1203</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1204
1205</div>
1206
1207<!-- ======================================================================= -->
1208<div class="doc_subsubsection">
1209 <a name="ccxx_basic_unsigned_char">unsigned char</a>
1210</div>
1211
1212<div class="doc_text">
1213
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1214<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1215<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1216!2 = metadata !{
1217 i32 458788, ;; Tag
1218 metadata !1, ;; Context
1219 metadata !"unsigned char",
1220 metadata !1, ;; Compile Unit
1221 i32 0, ;; Line number
1222 i64 8, ;; Size in Bits
1223 i64 8, ;; Align in Bits
1224 i64 0, ;; Offset in Bits
1225 i32 0, ;; Flags
1226 i32 8 ;; Encoding
1227}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1228</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1229</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1230
1231</div>
1232
1233<!-- ======================================================================= -->
1234<div class="doc_subsubsection">
1235 <a name="ccxx_basic_short">short</a>
1236</div>
1237
1238<div class="doc_text">
1239
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1240<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1241<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1242!2 = metadata !{
1243 i32 458788, ;; Tag
1244 metadata !1, ;; Context
1245 metadata !"short int",
1246 metadata !1, ;; Compile Unit
1247 i32 0, ;; Line number
1248 i64 16, ;; Size in Bits
1249 i64 16, ;; Align in Bits
1250 i64 0, ;; Offset in Bits
1251 i32 0, ;; Flags
1252 i32 5 ;; Encoding
1253}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1254</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1255</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1256
1257</div>
1258
1259<!-- ======================================================================= -->
1260<div class="doc_subsubsection">
1261 <a name="ccxx_basic_unsigned_short">unsigned short</a>
1262</div>
1263
1264<div class="doc_text">
1265
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1266<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1267<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1268!2 = metadata !{
1269 i32 458788, ;; Tag
1270 metadata !1, ;; Context
1271 metadata !"short unsigned int",
1272 metadata !1, ;; Compile Unit
1273 i32 0, ;; Line number
1274 i64 16, ;; Size in Bits
1275 i64 16, ;; Align in Bits
1276 i64 0, ;; Offset in Bits
1277 i32 0, ;; Flags
1278 i32 7 ;; Encoding
1279}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1280</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1281</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1282
1283</div>
1284
1285<!-- ======================================================================= -->
1286<div class="doc_subsubsection">
1287 <a name="ccxx_basic_int">int</a>
1288</div>
1289
1290<div class="doc_text">
1291
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1292<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1293<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1294!2 = metadata !{
1295 i32 458788, ;; Tag
1296 metadata !1, ;; Context
1297 metadata !"int", ;; Name
1298 metadata !1, ;; Compile Unit
1299 i32 0, ;; Line number
1300 i64 32, ;; Size in Bits
1301 i64 32, ;; Align in Bits
1302 i64 0, ;; Offset in Bits
1303 i32 0, ;; Flags
1304 i32 5 ;; Encoding
1305}
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1306</pre></div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1307
1308</div>
1309
1310<!-- ======================================================================= -->
1311<div class="doc_subsubsection">
1312 <a name="ccxx_basic_unsigned_int">unsigned int</a>
1313</div>
1314
1315<div class="doc_text">
1316
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1317<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1318<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1319!2 = metadata !{
1320 i32 458788, ;; Tag
1321 metadata !1, ;; Context
1322 metadata !"unsigned int",
1323 metadata !1, ;; Compile Unit
1324 i32 0, ;; Line number
1325 i64 32, ;; Size in Bits
1326 i64 32, ;; Align in Bits
1327 i64 0, ;; Offset in Bits
1328 i32 0, ;; Flags
1329 i32 7 ;; Encoding
1330}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1331</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1332</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1333
1334</div>
1335
1336<!-- ======================================================================= -->
1337<div class="doc_subsubsection">
1338 <a name="ccxx_basic_long_long">long long</a>
1339</div>
1340
1341<div class="doc_text">
1342
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1343<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1344<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1345!2 = metadata !{
1346 i32 458788, ;; Tag
1347 metadata !1, ;; Context
1348 metadata !"long long int",
1349 metadata !1, ;; Compile Unit
1350 i32 0, ;; Line number
1351 i64 64, ;; Size in Bits
1352 i64 64, ;; Align in Bits
1353 i64 0, ;; Offset in Bits
1354 i32 0, ;; Flags
1355 i32 5 ;; Encoding
1356}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1357</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1358</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1359
1360</div>
1361
1362<!-- ======================================================================= -->
1363<div class="doc_subsubsection">
1364 <a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
1365</div>
1366
1367<div class="doc_text">
1368
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1369<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1370<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1371!2 = metadata !{
1372 i32 458788, ;; Tag
1373 metadata !1, ;; Context
1374 metadata !"long long unsigned int",
1375 metadata !1, ;; Compile Unit
1376 i32 0, ;; Line number
1377 i64 64, ;; Size in Bits
1378 i64 64, ;; Align in Bits
1379 i64 0, ;; Offset in Bits
1380 i32 0, ;; Flags
1381 i32 7 ;; Encoding
1382}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1383</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1384</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1385
1386</div>
1387
1388<!-- ======================================================================= -->
1389<div class="doc_subsubsection">
1390 <a name="ccxx_basic_float">float</a>
1391</div>
1392
1393<div class="doc_text">
1394
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1395<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1396<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1397!2 = metadata !{
1398 i32 458788, ;; Tag
1399 metadata !1, ;; Context
1400 metadata !"float",
1401 metadata !1, ;; Compile Unit
1402 i32 0, ;; Line number
1403 i64 32, ;; Size in Bits
1404 i64 32, ;; Align in Bits
1405 i64 0, ;; Offset in Bits
1406 i32 0, ;; Flags
1407 i32 4 ;; Encoding
1408}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1409</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1410</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1411
1412</div>
1413
1414<!-- ======================================================================= -->
1415<div class="doc_subsubsection">
1416 <a name="ccxx_basic_double">double</a>
1417</div>
1418
1419<div class="doc_text">
1420
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1421<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1422<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1423!2 = metadata !{
1424 i32 458788, ;; Tag
1425 metadata !1, ;; Context
1426 metadata !"double",;; Name
1427 metadata !1, ;; Compile Unit
1428 i32 0, ;; Line number
1429 i64 64, ;; Size in Bits
1430 i64 64, ;; Align in Bits
1431 i64 0, ;; Offset in Bits
1432 i32 0, ;; Flags
1433 i32 4 ;; Encoding
1434}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1435</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1436</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1437
1438</div>
1439
1440<!-- ======================================================================= -->
1441<div class="doc_subsection">
1442 <a name="ccxx_derived_types">C/C++ derived types</a>
1443</div>
1444
1445<div class="doc_text">
1446
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1447<p>Given the following as an example of C/C++ derived type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1448
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1449<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1450<pre>
1451typedef const int *IntPtr;
1452</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1453</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1454
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1455<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1456
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1457<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1458<pre>
1459;;
1460;; Define the typedef "IntPtr".
1461;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1462!2 = metadata !{
1463 i32 458774, ;; Tag
1464 metadata !1, ;; Context
1465 metadata !"IntPtr", ;; Name
1466 metadata !3, ;; Compile unit
1467 i32 0, ;; Line number
1468 i64 0, ;; Size in bits
1469 i64 0, ;; Align in bits
1470 i64 0, ;; Offset in bits
1471 i32 0, ;; Flags
1472 metadata !4 ;; Derived From type
1473}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1474
1475;;
1476;; Define the pointer type.
1477;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1478!4 = metadata !{
1479 i32 458767, ;; Tag
1480 metadata !1, ;; Context
1481 metadata !"", ;; Name
1482 metadata !1, ;; Compile unit
1483 i32 0, ;; Line number
1484 i64 64, ;; Size in bits
1485 i64 64, ;; Align in bits
1486 i64 0, ;; Offset in bits
1487 i32 0, ;; Flags
1488 metadata !5 ;; Derived From type
1489}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1490;;
1491;; Define the const type.
1492;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1493!5 = metadata !{
1494 i32 458790, ;; Tag
1495 metadata !1, ;; Context
1496 metadata !"", ;; Name
1497 metadata !1, ;; Compile unit
1498 i32 0, ;; Line number
1499 i64 32, ;; Size in bits
1500 i64 32, ;; Align in bits
1501 i64 0, ;; Offset in bits
1502 i32 0, ;; Flags
1503 metadata !6 ;; Derived From type
1504}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1505;;
1506;; Define the int type.
1507;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1508!6 = metadata !{
1509 i32 458788, ;; Tag
1510 metadata !1, ;; Context
1511 metadata !"int", ;; Name
1512 metadata !1, ;; Compile unit
1513 i32 0, ;; Line number
1514 i64 32, ;; Size in bits
1515 i64 32, ;; Align in bits
1516 i64 0, ;; Offset in bits
1517 i32 0, ;; Flags
1518 5 ;; Encoding
1519}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1520</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1521</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1522
1523</div>
1524
1525<!-- ======================================================================= -->
1526<div class="doc_subsection">
1527 <a name="ccxx_composite_types">C/C++ struct/union types</a>
1528</div>
1529
1530<div class="doc_text">
1531
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1532<p>Given the following as an example of C/C++ struct type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1533
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1534<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1535<pre>
1536struct Color {
1537 unsigned Red;
1538 unsigned Green;
1539 unsigned Blue;
1540};
1541</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1542</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1543
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1544<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1545
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1546<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1547<pre>
1548;;
1549;; Define basic type for unsigned int.
1550;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1551!5 = metadata !{
1552 i32 458788, ;; Tag
1553 metadata !1, ;; Context
1554 metadata !"unsigned int",
1555 metadata !1, ;; Compile Unit
1556 i32 0, ;; Line number
1557 i64 32, ;; Size in Bits
1558 i64 32, ;; Align in Bits
1559 i64 0, ;; Offset in Bits
1560 i32 0, ;; Flags
1561 i32 7 ;; Encoding
1562}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1563;;
1564;; Define composite type for struct Color.
1565;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1566!2 = metadata !{
1567 i32 458771, ;; Tag
1568 metadata !1, ;; Context
1569 metadata !"Color", ;; Name
1570 metadata !1, ;; Compile unit
1571 i32 1, ;; Line number
1572 i64 96, ;; Size in bits
1573 i64 32, ;; Align in bits
1574 i64 0, ;; Offset in bits
1575 i32 0, ;; Flags
1576 null, ;; Derived From
1577 metadata !3, ;; Elements
1578 i32 0 ;; Runtime Language
1579}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1580
1581;;
1582;; Define the Red field.
1583;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1584!4 = metadata !{
1585 i32 458765, ;; Tag
1586 metadata !1, ;; Context
1587 metadata !"Red", ;; Name
1588 metadata !1, ;; Compile Unit
1589 i32 2, ;; Line number
1590 i64 32, ;; Size in bits
1591 i64 32, ;; Align in bits
1592 i64 0, ;; Offset in bits
1593 i32 0, ;; Flags
1594 metadata !5 ;; Derived From type
1595}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1596
1597;;
1598;; Define the Green field.
1599;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1600!6 = metadata !{
1601 i32 458765, ;; Tag
1602 metadata !1, ;; Context
1603 metadata !"Green", ;; Name
1604 metadata !1, ;; Compile Unit
1605 i32 3, ;; Line number
1606 i64 32, ;; Size in bits
1607 i64 32, ;; Align in bits
1608 i64 32, ;; Offset in bits
1609 i32 0, ;; Flags
1610 metadata !5 ;; Derived From type
1611}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1612
1613;;
1614;; Define the Blue field.
1615;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1616!7 = metadata !{
1617 i32 458765, ;; Tag
1618 metadata !1, ;; Context
1619 metadata !"Blue", ;; Name
1620 metadata !1, ;; Compile Unit
1621 i32 4, ;; Line number
1622 i64 32, ;; Size in bits
1623 i64 32, ;; Align in bits
1624 i64 64, ;; Offset in bits
1625 i32 0, ;; Flags
1626 metadata !5 ;; Derived From type
1627}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1628
1629;;
1630;; Define the array of fields used by the composite type Color.
1631;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1632!3 = metadata !{metadata !4, metadata !6, metadata !7}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1633</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1634</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1635
1636</div>
1637
1638<!-- ======================================================================= -->
1639<div class="doc_subsection">
1640 <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
1641</div>
1642
1643<div class="doc_text">
1644
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1645<p>Given the following as an example of C/C++ enumeration type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1646
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1647<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1648<pre>
1649enum Trees {
1650 Spruce = 100,
1651 Oak = 200,
1652 Maple = 300
1653};
1654</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1655</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1656
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1657<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1658
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1659<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1660<pre>
1661;;
1662;; Define composite type for enum Trees
1663;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1664!2 = metadata !{
1665 i32 458756, ;; Tag
1666 metadata !1, ;; Context
1667 metadata !"Trees", ;; Name
1668 metadata !1, ;; Compile unit
1669 i32 1, ;; Line number
1670 i64 32, ;; Size in bits
1671 i64 32, ;; Align in bits
1672 i64 0, ;; Offset in bits
1673 i32 0, ;; Flags
1674 null, ;; Derived From type
1675 metadata !3, ;; Elements
1676 i32 0 ;; Runtime language
1677}
Devang Patel2a610c72009-08-25 05:24:07 +0000[diff] [blame]1678
Devang Patel82459882009-08-26 05:01:18 +0000[diff] [blame]1679;;
1680;; Define the array of enumerators used by composite type Trees.
1681;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1682!3 = metadata !{metadata !4, metadata !5, metadata !6}
1683
1684;;
1685;; Define Spruce enumerator.
1686;;
1687!4 = metadata !{i32 458792, metadata !"Spruce", i64 100}
1688
1689;;
1690;; Define Oak enumerator.
1691;;
1692!5 = metadata !{i32 458792, metadata !"Oak", i64 200}
1693
1694;;
1695;; Define Maple enumerator.
1696;;
1697!6 = metadata !{i32 458792, metadata !"Maple", i64 300}
1698
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1699</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1700</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1701
1702</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1703
1704<!-- *********************************************************************** -->
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1705
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1706<hr>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1707<address>
1708 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1709 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1710 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1711 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1712
1713 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]1714 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1715 Last modified: $Date$
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1716</address>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1717
1718</body>
1719</html>