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Chris Lattnerbdfb3392004-01-05 05:06:33 +00006 <title>Source Level Debugging with LLVM</title>
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10
11<div class="doc_title">Source Level Debugging with LLVM</div>
12
Reid Spencerd3f876c2004-11-01 08:19:36 +000013<table class="layout" style="width:100%">
14 <tr class="layout">
15 <td class="left">
Chris Lattnerbdfb3392004-01-05 05:06:33 +000016<ul>
Misha Brukman82873732004-05-12 19:21:57 +000017 <li><a href="#introduction">Introduction</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +000018 <ol>
19 <li><a href="#phil">Philosophy behind LLVM debugging information</a></li>
Jim Laskey383e0092006-03-23 17:54:33 +000020 <li><a href="#consumers">Debug information consumers</a></li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +000021 <li><a href="#debugopt">Debugging optimized code</a></li>
Misha Brukman82873732004-05-12 19:21:57 +000022 </ol></li>
Misha Brukman82873732004-05-12 19:21:57 +000023 <li><a href="#format">Debugging information format</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +000024 <ol>
Jim Laskeycec12a52006-03-14 18:08:46 +000025 <li><a href="#debug_info_descriptors">Debug information descriptors</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +000026 <ul>
Jim Laskeycec12a52006-03-14 18:08:46 +000027 <li><a href="#format_compile_units">Compile unit descriptors</a></li>
Devang Patel4b945502010-03-09 00:44:10 +000028 <li><a href="#format_files">File descriptors</a></li>
Jim Laskeycec12a52006-03-14 18:08:46 +000029 <li><a href="#format_global_variables">Global variable descriptors</a></li>
30 <li><a href="#format_subprograms">Subprogram descriptors</a></li>
Jim Laskey3d11bee2006-03-15 19:10:52 +000031 <li><a href="#format_blocks">Block descriptors</a></li>
Jim Laskeycec12a52006-03-14 18:08:46 +000032 <li><a href="#format_basic_type">Basic type descriptors</a></li>
33 <li><a href="#format_derived_type">Derived type descriptors</a></li>
34 <li><a href="#format_composite_type">Composite type descriptors</a></li>
35 <li><a href="#format_subrange">Subrange descriptors</a></li>
36 <li><a href="#format_enumeration">Enumerator descriptors</a></li>
Jim Laskey383e0092006-03-23 17:54:33 +000037 <li><a href="#format_variables">Local variables</a></li>
Misha Brukman82873732004-05-12 19:21:57 +000038 </ul></li>
Jim Laskeycec12a52006-03-14 18:08:46 +000039 <li><a href="#format_common_intrinsics">Debugger intrinsic functions</a>
40 <ul>
Jim Laskeycec12a52006-03-14 18:08:46 +000041 <li><a href="#format_common_declare">llvm.dbg.declare</a></li>
Victor Hernandez67a1a542010-01-11 22:53:48 +000042 <li><a href="#format_common_value">llvm.dbg.value</a></li>
Jim Laskeycec12a52006-03-14 18:08:46 +000043 </ul></li>
Misha Brukman82873732004-05-12 19:21:57 +000044 </ol></li>
Devang Patel744950d2009-11-25 23:28:01 +000045 <li><a href="#format_common_lifetime">Object lifetimes and scoping</a></li>
Misha Brukman82873732004-05-12 19:21:57 +000046 <li><a href="#ccxx_frontend">C/C++ front-end specific debug information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +000047 <ol>
Jim Laskeycec12a52006-03-14 18:08:46 +000048 <li><a href="#ccxx_compile_units">C/C++ source file information</a></li>
49 <li><a href="#ccxx_global_variable">C/C++ global variable information</a></li>
50 <li><a href="#ccxx_subprogram">C/C++ function information</a></li>
51 <li><a href="#ccxx_basic_types">C/C++ basic types</a></li>
52 <li><a href="#ccxx_derived_types">C/C++ derived types</a></li>
53 <li><a href="#ccxx_composite_types">C/C++ struct/union types</a></li>
54 <li><a href="#ccxx_enumeration_types">C/C++ enumeration types</a></li>
Misha Brukman82873732004-05-12 19:21:57 +000055 </ol></li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +000056</ul>
Misha Brukman82873732004-05-12 19:21:57 +000057</td>
Reid Spencerd3f876c2004-11-01 08:19:36 +000058<td class="right">
Misha Brukmane849a1a2004-05-12 21:26:16 +000059<img src="img/venusflytrap.jpg" alt="A leafy and green bug eater" width="247"
Misha Brukman82873732004-05-12 19:21:57 +000060height="369">
61</td>
Reid Spencerd3f876c2004-11-01 08:19:36 +000062</tr></table>
Misha Brukman82873732004-05-12 19:21:57 +000063
Chris Lattner7911ce22004-05-23 21:07:27 +000064<div class="doc_author">
Jim Laskeycec12a52006-03-14 18:08:46 +000065 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
Jim Laskeyc760a922007-03-14 19:32:21 +000066 and <a href="mailto:jlaskey@mac.com">Jim Laskey</a></p>
Chris Lattner7911ce22004-05-23 21:07:27 +000067</div>
68
Chris Lattnerbdfb3392004-01-05 05:06:33 +000069
70<!-- *********************************************************************** -->
Misha Brukman94218a72004-12-09 20:27:37 +000071<div class="doc_section"><a name="introduction">Introduction</a></div>
72<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +000073
74<div class="doc_text">
75
76<p>This document is the central repository for all information pertaining to
Bill Wendling48839d92009-05-17 05:52:39 +000077 debug information in LLVM. It describes the <a href="#format">actual format
78 that the LLVM debug information</a> takes, which is useful for those
79 interested in creating front-ends or dealing directly with the information.
Chris Lattner8ad2f982009-07-18 21:47:15 +000080 Further, this document provides specific examples of what debug information
Bill Wendling48839d92009-05-17 05:52:39 +000081 for C/C++.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +000082
83</div>
84
85<!-- ======================================================================= -->
86<div class="doc_subsection">
87 <a name="phil">Philosophy behind LLVM debugging information</a>
88</div>
89
90<div class="doc_text">
91
Misha Brukman82873732004-05-12 19:21:57 +000092<p>The idea of the LLVM debugging information is to capture how the important
Bill Wendling48839d92009-05-17 05:52:39 +000093 pieces of the source-language's Abstract Syntax Tree map onto LLVM code.
94 Several design aspects have shaped the solution that appears here. The
95 important ones are:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +000096
Misha Brukman82873732004-05-12 19:21:57 +000097<ul>
Bill Wendling48839d92009-05-17 05:52:39 +000098 <li>Debugging information should have very little impact on the rest of the
99 compiler. No transformations, analyses, or code generators should need to
100 be modified because of debugging information.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000101
Bill Wendling48839d92009-05-17 05:52:39 +0000102 <li>LLVM optimizations should interact in <a href="#debugopt">well-defined and
103 easily described ways</a> with the debugging information.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000104
Bill Wendling48839d92009-05-17 05:52:39 +0000105 <li>Because LLVM is designed to support arbitrary programming languages,
106 LLVM-to-LLVM tools should not need to know anything about the semantics of
107 the source-level-language.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000108
Bill Wendling48839d92009-05-17 05:52:39 +0000109 <li>Source-level languages are often <b>widely</b> different from one another.
110 LLVM should not put any restrictions of the flavor of the source-language,
111 and the debugging information should work with any language.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000112
Bill Wendling48839d92009-05-17 05:52:39 +0000113 <li>With code generator support, it should be possible to use an LLVM compiler
114 to compile a program to native machine code and standard debugging
115 formats. This allows compatibility with traditional machine-code level
116 debuggers, like GDB or DBX.</li>
Misha Brukman82873732004-05-12 19:21:57 +0000117</ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000118
Bill Wendling48839d92009-05-17 05:52:39 +0000119<p>The approach used by the LLVM implementation is to use a small set
120 of <a href="#format_common_intrinsics">intrinsic functions</a> to define a
121 mapping between LLVM program objects and the source-level objects. The
Devang Patele4b27562009-08-28 23:24:31 +0000122 description of the source-level program is maintained in LLVM metadata
123 in an <a href="#ccxx_frontend">implementation-defined format</a>
Bill Wendling48839d92009-05-17 05:52:39 +0000124 (the C/C++ front-end currently uses working draft 7 of
125 the <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3
126 standard</a>).</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000127
Jim Laskeycec12a52006-03-14 18:08:46 +0000128<p>When a program is being debugged, a debugger interacts with the user and
Bill Wendling48839d92009-05-17 05:52:39 +0000129 turns the stored debug information into source-language specific information.
130 As such, a debugger must be aware of the source-language, and is thus tied to
131 a specific language or family of languages.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000132
133</div>
134
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000135<!-- ======================================================================= -->
136<div class="doc_subsection">
Jim Laskey383e0092006-03-23 17:54:33 +0000137 <a name="consumers">Debug information consumers</a>
138</div>
139
140<div class="doc_text">
Bill Wendling48839d92009-05-17 05:52:39 +0000141
Jim Laskey383e0092006-03-23 17:54:33 +0000142<p>The role of debug information is to provide meta information normally
Bill Wendling48839d92009-05-17 05:52:39 +0000143 stripped away during the compilation process. This meta information provides
144 an LLVM user a relationship between generated code and the original program
145 source code.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000146
Chris Lattnerc3107782010-04-05 04:11:11 +0000147<p>Currently, debug information is consumed by DwarfDebug to produce dwarf
Bill Wendling48839d92009-05-17 05:52:39 +0000148 information used by the gdb debugger. Other targets could use the same
149 information to produce stabs or other debug forms.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000150
151<p>It would also be reasonable to use debug information to feed profiling tools
Bill Wendling48839d92009-05-17 05:52:39 +0000152 for analysis of generated code, or, tools for reconstructing the original
153 source from generated code.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000154
155<p>TODO - expound a bit more.</p>
156
157</div>
158
159<!-- ======================================================================= -->
160<div class="doc_subsection">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000161 <a name="debugopt">Debugging optimized code</a>
162</div>
163
164<div class="doc_text">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000165
Misha Brukman82873732004-05-12 19:21:57 +0000166<p>An extremely high priority of LLVM debugging information is to make it
Bill Wendling48839d92009-05-17 05:52:39 +0000167 interact well with optimizations and analysis. In particular, the LLVM debug
168 information provides the following guarantees:</p>
Misha Brukman82873732004-05-12 19:21:57 +0000169
170<ul>
Bill Wendling48839d92009-05-17 05:52:39 +0000171 <li>LLVM debug information <b>always provides information to accurately read
172 the source-level state of the program</b>, regardless of which LLVM
173 optimizations have been run, and without any modification to the
174 optimizations themselves. However, some optimizations may impact the
175 ability to modify the current state of the program with a debugger, such
176 as setting program variables, or calling functions that have been
177 deleted.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000178
Bill Wendling48839d92009-05-17 05:52:39 +0000179 <li>LLVM optimizations gracefully interact with debugging information. If
180 they are not aware of debug information, they are automatically disabled
181 as necessary in the cases that would invalidate the debug info. This
182 retains the LLVM features, making it easy to write new
183 transformations.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000184
Bill Wendling48839d92009-05-17 05:52:39 +0000185 <li>As desired, LLVM optimizations can be upgraded to be aware of the LLVM
186 debugging information, allowing them to update the debugging information
187 as they perform aggressive optimizations. This means that, with effort,
188 the LLVM optimizers could optimize debug code just as well as non-debug
189 code.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000190
Bill Wendling48839d92009-05-17 05:52:39 +0000191 <li>LLVM debug information does not prevent many important optimizations from
192 happening (for example inlining, basic block reordering/merging/cleanup,
193 tail duplication, etc), further reducing the amount of the compiler that
194 eventually is "aware" of debugging information.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000195
Bill Wendling48839d92009-05-17 05:52:39 +0000196 <li>LLVM debug information is automatically optimized along with the rest of
197 the program, using existing facilities. For example, duplicate
198 information is automatically merged by the linker, and unused information
199 is automatically removed.</li>
Misha Brukman82873732004-05-12 19:21:57 +0000200</ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000201
Misha Brukman82873732004-05-12 19:21:57 +0000202<p>Basically, the debug information allows you to compile a program with
Bill Wendling48839d92009-05-17 05:52:39 +0000203 "<tt>-O0 -g</tt>" and get full debug information, allowing you to arbitrarily
204 modify the program as it executes from a debugger. Compiling a program with
205 "<tt>-O3 -g</tt>" gives you full debug information that is always available
206 and accurate for reading (e.g., you get accurate stack traces despite tail
207 call elimination and inlining), but you might lose the ability to modify the
208 program and call functions where were optimized out of the program, or
209 inlined away completely.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000210
Misha Brukman96e00812008-12-16 02:54:22 +0000211<p><a href="TestingGuide.html#quicktestsuite">LLVM test suite</a> provides a
Bill Wendling48839d92009-05-17 05:52:39 +0000212 framework to test optimizer's handling of debugging information. It can be
213 run like this:</p>
Devang Patela5c05aa2008-11-21 19:35:57 +0000214
215<div class="doc_code">
216<pre>
217% cd llvm/projects/test-suite/MultiSource/Benchmarks # or some other level
218% make TEST=dbgopt
219</pre>
220</div>
221
Bill Wendling48839d92009-05-17 05:52:39 +0000222<p>This will test impact of debugging information on optimization passes. If
223 debugging information influences optimization passes then it will be reported
224 as a failure. See <a href="TestingGuide.html">TestingGuide</a> for more
225 information on LLVM test infrastructure and how to run various tests.</p>
Devang Patela5c05aa2008-11-21 19:35:57 +0000226
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000227</div>
228
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000229<!-- *********************************************************************** -->
230<div class="doc_section">
Chris Lattner8ff75902004-01-06 05:31:32 +0000231 <a name="format">Debugging information format</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000232</div>
233<!-- *********************************************************************** -->
234
235<div class="doc_text">
236
237<p>LLVM debugging information has been carefully designed to make it possible
Bill Wendling48839d92009-05-17 05:52:39 +0000238 for the optimizer to optimize the program and debugging information without
239 necessarily having to know anything about debugging information. In
John Criswellb34500f2010-03-17 15:01:50 +0000240 particular, the use of metadata avoids duplicated debugging information from
Devang Patele4b27562009-08-28 23:24:31 +0000241 the beginning, and the global dead code elimination pass automatically
242 deletes debugging information for a function if it decides to delete the
243 function. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000244
245<p>To do this, most of the debugging information (descriptors for types,
Bill Wendling48839d92009-05-17 05:52:39 +0000246 variables, functions, source files, etc) is inserted by the language
Devang Patele4b27562009-08-28 23:24:31 +0000247 front-end in the form of LLVM metadata. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000248
Jim Laskeycec12a52006-03-14 18:08:46 +0000249<p>Debug information is designed to be agnostic about the target debugger and
Bill Wendling48839d92009-05-17 05:52:39 +0000250 debugging information representation (e.g. DWARF/Stabs/etc). It uses a
Devang Patele4b27562009-08-28 23:24:31 +0000251 generic pass to decode the information that represents variables, types,
252 functions, namespaces, etc: this allows for arbitrary source-language
253 semantics and type-systems to be used, as long as there is a module
254 written for the target debugger to interpret the information. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000255
Misha Brukman82873732004-05-12 19:21:57 +0000256<p>To provide basic functionality, the LLVM debugger does have to make some
Bill Wendling48839d92009-05-17 05:52:39 +0000257 assumptions about the source-level language being debugged, though it keeps
258 these to a minimum. The only common features that the LLVM debugger assumes
Devang Patel4b945502010-03-09 00:44:10 +0000259 exist are <a href="#format_files">source files</a>,
Bill Wendling48839d92009-05-17 05:52:39 +0000260 and <a href="#format_global_variables">program objects</a>. These abstract
261 objects are used by a debugger to form stack traces, show information about
262 local variables, etc.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000263
264<p>This section of the documentation first describes the representation aspects
Bill Wendling48839d92009-05-17 05:52:39 +0000265 common to any source-language. The <a href="#ccxx_frontend">next section</a>
266 describes the data layout conventions used by the C and C++ front-ends.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000267
268</div>
269
270<!-- ======================================================================= -->
271<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000272 <a name="debug_info_descriptors">Debug information descriptors</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000273</div>
274
275<div class="doc_text">
Bill Wendling48839d92009-05-17 05:52:39 +0000276
Jim Laskeycec12a52006-03-14 18:08:46 +0000277<p>In consideration of the complexity and volume of debug information, LLVM
Devang Patele4b27562009-08-28 23:24:31 +0000278 provides a specification for well formed debug descriptors. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000279
Jim Laskeycec12a52006-03-14 18:08:46 +0000280<p>Consumers of LLVM debug information expect the descriptors for program
Bill Wendling48839d92009-05-17 05:52:39 +0000281 objects to start in a canonical format, but the descriptors can include
282 additional information appended at the end that is source-language
283 specific. All LLVM debugging information is versioned, allowing backwards
284 compatibility in the case that the core structures need to change in some
285 way. Also, all debugging information objects start with a tag to indicate
286 what type of object it is. The source-language is allowed to define its own
287 objects, by using unreserved tag numbers. We recommend using with tags in
Benjamin Kramer8040cd32009-10-12 14:46:08 +0000288 the range 0x1000 through 0x2000 (there is a defined enum DW_TAG_user_base =
Bill Wendling48839d92009-05-17 05:52:39 +0000289 0x1000.)</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000290
Devang Patele4b27562009-08-28 23:24:31 +0000291<p>The fields of debug descriptors used internally by LLVM
Nick Lewycky655fd032010-03-31 07:50:17 +0000292 are restricted to only the simple data types <tt>i32</tt>, <tt>i1</tt>,
293 <tt>float</tt>, <tt>double</tt>, <tt>mdstring</tt> and <tt>mdnode</tt>. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000294
Bill Wendling48839d92009-05-17 05:52:39 +0000295<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000296<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000297!1 = metadata !{
Nick Lewycky655fd032010-03-31 07:50:17 +0000298 i32, ;; A tag
Bill Wendling48839d92009-05-17 05:52:39 +0000299 ...
300}
Misha Brukman82873732004-05-12 19:21:57 +0000301</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000302</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000303
Jim Laskey7089f452006-06-16 13:14:03 +0000304<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
Nick Lewycky655fd032010-03-31 07:50:17 +0000305 <tt>i32</tt> containing a tag value identifying the content of the
Bill Wendling48839d92009-05-17 05:52:39 +0000306 descriptor. The remaining fields are specific to the descriptor. The values
307 of tags are loosely bound to the tag values of DWARF information entries.
308 However, that does not restrict the use of the information supplied to DWARF
309 targets. To facilitate versioning of debug information, the tag is augmented
Nick Lewycky655fd032010-03-31 07:50:17 +0000310 with the current debug version (LLVMDebugVersion = 8 &lt;&lt; 16 or 0x80000 or
Devang Patel4b945502010-03-09 00:44:10 +0000311 524288.)</a></p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000312
Jim Laskey7089f452006-06-16 13:14:03 +0000313<p>The details of the various descriptors follow.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000314
315</div>
316
317<!-- ======================================================================= -->
318<div class="doc_subsubsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000319 <a name="format_compile_units">Compile unit descriptors</a>
320</div>
321
322<div class="doc_text">
323
Bill Wendling48839d92009-05-17 05:52:39 +0000324<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000325<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000326!0 = metadata !{
327 i32, ;; Tag = 17 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
328 ;; (DW_TAG_compile_unit)
329 i32, ;; Unused field.
330 i32, ;; DWARF language identifier (ex. DW_LANG_C89)
331 metadata, ;; Source file name
332 metadata, ;; Source file directory (includes trailing slash)
333 metadata ;; Producer (ex. "4.0.1 LLVM (LLVM research group)")
334 i1, ;; True if this is a main compile unit.
335 i1, ;; True if this is optimized.
336 metadata, ;; Flags
337 i32 ;; Runtime version
Bill Wendling48839d92009-05-17 05:52:39 +0000338}
Jim Laskeycec12a52006-03-14 18:08:46 +0000339</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000340</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000341
Bill Wendling48839d92009-05-17 05:52:39 +0000342<p>These descriptors contain a source language ID for the file (we use the DWARF
343 3.0 ID numbers, such as <tt>DW_LANG_C89</tt>, <tt>DW_LANG_C_plus_plus</tt>,
344 <tt>DW_LANG_Cobol74</tt>, etc), three strings describing the filename,
345 working directory of the compiler, and an identifier string for the compiler
346 that produced it.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000347
Bill Wendling48839d92009-05-17 05:52:39 +0000348<p>Compile unit descriptors provide the root context for objects declared in a
Devang Patel4b945502010-03-09 00:44:10 +0000349 specific compilation unit. File descriptors are defined using this context.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000350
Devang Patel4b945502010-03-09 00:44:10 +0000351</div>
352
353<!-- ======================================================================= -->
354<div class="doc_subsubsection">
355 <a name="format_files">File descriptors</a>
356</div>
357
358<div class="doc_text">
359
360<div class="doc_code">
361<pre>
362!0 = metadata !{
363 i32, ;; Tag = 41 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
364 ;; (DW_TAG_file_type)
365 metadata, ;; Source file name
366 metadata, ;; Source file directory (includes trailing slash)
367 metadata ;; Reference to compile unit where defined
368}
369</pre>
370</div>
371
John Criswellb34500f2010-03-17 15:01:50 +0000372<p>These descriptors contain information for a file. Global variables and top
Devang Patel4b945502010-03-09 00:44:10 +0000373 level functions would be defined using this context.k File descriptors also
374 provide context for source line correspondence. </p>
375
376<p>Each input file is encoded as a separate file descriptor in LLVM debugging
377 information output. Each file descriptor would be defined using a
378 compile unit. </p>
Bill Wendling48839d92009-05-17 05:52:39 +0000379
Jim Laskeycec12a52006-03-14 18:08:46 +0000380</div>
381
382<!-- ======================================================================= -->
383<div class="doc_subsubsection">
384 <a name="format_global_variables">Global variable descriptors</a>
385</div>
386
387<div class="doc_text">
388
Bill Wendling48839d92009-05-17 05:52:39 +0000389<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000390<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000391!1 = metadata !{
392 i32, ;; Tag = 52 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
393 ;; (DW_TAG_variable)
394 i32, ;; Unused field.
395 metadata, ;; Reference to context descriptor
396 metadata, ;; Name
397 metadata, ;; Display name (fully qualified C++ name)
398 metadata, ;; MIPS linkage name (for C++)
Devang Patel4b945502010-03-09 00:44:10 +0000399 metadata, ;; Reference to file where defined
Devang Patele4b27562009-08-28 23:24:31 +0000400 i32, ;; Line number where defined
401 metadata, ;; Reference to type descriptor
402 i1, ;; True if the global is local to compile unit (static)
403 i1, ;; True if the global is defined in the compile unit (not extern)
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000404 {}* ;; Reference to the global variable
Bill Wendling48839d92009-05-17 05:52:39 +0000405}
Jim Laskeycec12a52006-03-14 18:08:46 +0000406</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000407</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000408
409<p>These descriptors provide debug information about globals variables. The
410provide details such as name, type and where the variable is defined.</p>
411
412</div>
413
414<!-- ======================================================================= -->
415<div class="doc_subsubsection">
416 <a name="format_subprograms">Subprogram descriptors</a>
417</div>
418
419<div class="doc_text">
420
Bill Wendling48839d92009-05-17 05:52:39 +0000421<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000422<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000423!2 = metadata !{
424 i32, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
425 ;; (DW_TAG_subprogram)
426 i32, ;; Unused field.
427 metadata, ;; Reference to context descriptor
428 metadata, ;; Name
429 metadata, ;; Display name (fully qualified C++ name)
430 metadata, ;; MIPS linkage name (for C++)
Devang Patel4b945502010-03-09 00:44:10 +0000431 metadata, ;; Reference to file where defined
Devang Patele4b27562009-08-28 23:24:31 +0000432 i32, ;; Line number where defined
433 metadata, ;; Reference to type descriptor
434 i1, ;; True if the global is local to compile unit (static)
435 i1 ;; True if the global is defined in the compile unit (not extern)
Devang Patel80ecc152010-06-04 22:49:55 +0000436 i32 ;; Virtuality, e.g. dwarf::DW_VIRTUALITY__virtual
437 i32 ;; Index into a virtual function
438 metadata, ;; indicates which base type contains the vtable pointer for the
439 ;; derived class
440 i1 ;; isArtificial
441 i1 ;; isOptimized
442 Function *;; Pointer to LLVM function
Bill Wendling48839d92009-05-17 05:52:39 +0000443}
Jim Laskeycec12a52006-03-14 18:08:46 +0000444</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000445</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000446
447<p>These descriptors provide debug information about functions, methods and
Bill Wendling48839d92009-05-17 05:52:39 +0000448 subprograms. They provide details such as name, return types and the source
449 location where the subprogram is defined.</p>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000450
451</div>
Bill Wendling48839d92009-05-17 05:52:39 +0000452
Jim Laskey3d11bee2006-03-15 19:10:52 +0000453<!-- ======================================================================= -->
454<div class="doc_subsubsection">
455 <a name="format_blocks">Block descriptors</a>
456</div>
457
458<div class="doc_text">
459
Bill Wendling48839d92009-05-17 05:52:39 +0000460<div class="doc_code">
Jim Laskey3d11bee2006-03-15 19:10:52 +0000461<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000462!3 = metadata !{
463 i32, ;; Tag = 13 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
464 metadata ;; Reference to context descriptor
Bill Wendling48839d92009-05-17 05:52:39 +0000465}
Jim Laskey3d11bee2006-03-15 19:10:52 +0000466</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000467</div>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000468
469<p>These descriptors provide debug information about nested blocks within a
Bill Wendling48839d92009-05-17 05:52:39 +0000470 subprogram. The array of member descriptors is used to define local
471 variables and deeper nested blocks.</p>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000472
Jim Laskeycec12a52006-03-14 18:08:46 +0000473</div>
474
475<!-- ======================================================================= -->
476<div class="doc_subsubsection">
477 <a name="format_basic_type">Basic type descriptors</a>
478</div>
479
480<div class="doc_text">
481
Bill Wendling48839d92009-05-17 05:52:39 +0000482<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000483<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000484!4 = metadata !{
485 i32, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
486 ;; (DW_TAG_base_type)
487 metadata, ;; Reference to context (typically a compile unit)
488 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000489 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000490 i32, ;; Line number where defined (may be 0)
491 i64, ;; Size in bits
492 i64, ;; Alignment in bits
493 i64, ;; Offset in bits
494 i32, ;; Flags
495 i32 ;; DWARF type encoding
Bill Wendling48839d92009-05-17 05:52:39 +0000496}
Jim Laskeycec12a52006-03-14 18:08:46 +0000497</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000498</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000499
500<p>These descriptors define primitive types used in the code. Example int, bool
Bill Wendling48839d92009-05-17 05:52:39 +0000501 and float. The context provides the scope of the type, which is usually the
502 top level. Since basic types are not usually user defined the compile unit
503 and line number can be left as NULL and 0. The size, alignment and offset
504 are expressed in bits and can be 64 bit values. The alignment is used to
505 round the offset when embedded in a
506 <a href="#format_composite_type">composite type</a> (example to keep float
507 doubles on 64 bit boundaries.) The offset is the bit offset if embedded in
508 a <a href="#format_composite_type">composite type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000509
510<p>The type encoding provides the details of the type. The values are typically
Bill Wendling48839d92009-05-17 05:52:39 +0000511 one of the following:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000512
Bill Wendling48839d92009-05-17 05:52:39 +0000513<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000514<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000515DW_ATE_address = 1
516DW_ATE_boolean = 2
517DW_ATE_float = 4
518DW_ATE_signed = 5
519DW_ATE_signed_char = 6
520DW_ATE_unsigned = 7
521DW_ATE_unsigned_char = 8
Jim Laskeycec12a52006-03-14 18:08:46 +0000522</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000523</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000524
525</div>
526
527<!-- ======================================================================= -->
528<div class="doc_subsubsection">
529 <a name="format_derived_type">Derived type descriptors</a>
530</div>
531
532<div class="doc_text">
533
Bill Wendling48839d92009-05-17 05:52:39 +0000534<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000535<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000536!5 = metadata !{
537 i32, ;; Tag (see below)
538 metadata, ;; Reference to context
539 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000540 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000541 i32, ;; Line number where defined (may be 0)
542 i32, ;; Size in bits
543 i32, ;; Alignment in bits
544 i32, ;; Offset in bits
545 metadata ;; Reference to type derived from
Bill Wendling48839d92009-05-17 05:52:39 +0000546}
Jim Laskeycec12a52006-03-14 18:08:46 +0000547</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000548</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000549
550<p>These descriptors are used to define types derived from other types. The
551value of the tag varies depending on the meaning. The following are possible
Misha Brukman96e00812008-12-16 02:54:22 +0000552tag values:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000553
Bill Wendling48839d92009-05-17 05:52:39 +0000554<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000555<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000556DW_TAG_formal_parameter = 5
557DW_TAG_member = 13
558DW_TAG_pointer_type = 15
559DW_TAG_reference_type = 16
560DW_TAG_typedef = 22
561DW_TAG_const_type = 38
562DW_TAG_volatile_type = 53
563DW_TAG_restrict_type = 55
Jim Laskeycec12a52006-03-14 18:08:46 +0000564</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000565</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000566
Bill Wendling48839d92009-05-17 05:52:39 +0000567<p><tt>DW_TAG_member</tt> is used to define a member of
568 a <a href="#format_composite_type">composite type</a>
569 or <a href="#format_subprograms">subprogram</a>. The type of the member is
570 the <a href="#format_derived_type">derived
571 type</a>. <tt>DW_TAG_formal_parameter</tt> is used to define a member which
572 is a formal argument of a subprogram.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000573
Bill Wendling48839d92009-05-17 05:52:39 +0000574<p><tt>DW_TAG_typedef</tt> is used to provide a name for the derived type.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000575
Bill Wendling48839d92009-05-17 05:52:39 +0000576<p><tt>DW_TAG_pointer_type</tt>,<tt>DW_TAG_reference_type</tt>,
577 <tt>DW_TAG_const_type</tt>, <tt>DW_TAG_volatile_type</tt>
578 and <tt>DW_TAG_restrict_type</tt> are used to qualify
579 the <a href="#format_derived_type">derived type</a>. </p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000580
581<p><a href="#format_derived_type">Derived type</a> location can be determined
Bill Wendling48839d92009-05-17 05:52:39 +0000582 from the compile unit and line number. The size, alignment and offset are
583 expressed in bits and can be 64 bit values. The alignment is used to round
584 the offset when embedded in a <a href="#format_composite_type">composite
585 type</a> (example to keep float doubles on 64 bit boundaries.) The offset is
586 the bit offset if embedded in a <a href="#format_composite_type">composite
587 type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000588
589<p>Note that the <tt>void *</tt> type is expressed as a
Bill Wendling48839d92009-05-17 05:52:39 +0000590 <tt>llvm.dbg.derivedtype.type</tt> with tag of <tt>DW_TAG_pointer_type</tt>
591 and <tt>NULL</tt> derived type.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000592
593</div>
594
595<!-- ======================================================================= -->
596<div class="doc_subsubsection">
597 <a name="format_composite_type">Composite type descriptors</a>
598</div>
599
600<div class="doc_text">
601
Bill Wendling48839d92009-05-17 05:52:39 +0000602<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000603<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000604!6 = metadata !{
605 i32, ;; Tag (see below)
606 metadata, ;; Reference to context
607 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000608 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000609 i32, ;; Line number where defined (may be 0)
610 i64, ;; Size in bits
611 i64, ;; Alignment in bits
612 i64, ;; Offset in bits
613 i32, ;; Flags
614 metadata, ;; Reference to type derived from
615 metadata, ;; Reference to array of member descriptors
616 i32 ;; Runtime languages
Bill Wendling48839d92009-05-17 05:52:39 +0000617}
Jim Laskeycec12a52006-03-14 18:08:46 +0000618</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000619</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000620
621<p>These descriptors are used to define types that are composed of 0 or more
622elements. The value of the tag varies depending on the meaning. The following
Misha Brukman96e00812008-12-16 02:54:22 +0000623are possible tag values:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000624
Bill Wendling48839d92009-05-17 05:52:39 +0000625<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000626<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000627DW_TAG_array_type = 1
628DW_TAG_enumeration_type = 4
629DW_TAG_structure_type = 19
630DW_TAG_union_type = 23
631DW_TAG_vector_type = 259
Bruno Cardoso Lopesd80ddc02009-05-29 17:08:57 +0000632DW_TAG_subroutine_type = 21
633DW_TAG_inheritance = 28
Jim Laskeycec12a52006-03-14 18:08:46 +0000634</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000635</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000636
Jim Laskeyf8a01a92006-06-15 20:51:43 +0000637<p>The vector flag indicates that an array type is a native packed vector.</p>
638
Jim Laskey7089f452006-06-16 13:14:03 +0000639<p>The members of array types (tag = <tt>DW_TAG_array_type</tt>) or vector types
Bill Wendling48839d92009-05-17 05:52:39 +0000640 (tag = <tt>DW_TAG_vector_type</tt>) are <a href="#format_subrange">subrange
641 descriptors</a>, each representing the range of subscripts at that level of
642 indexing.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000643
644<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
Bill Wendling48839d92009-05-17 05:52:39 +0000645 <a href="#format_enumeration">enumerator descriptors</a>, each representing
646 the definition of enumeration value for the set.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000647
648<p>The members of structure (tag = <tt>DW_TAG_structure_type</tt>) or union (tag
Bill Wendling48839d92009-05-17 05:52:39 +0000649 = <tt>DW_TAG_union_type</tt>) types are any one of
650 the <a href="#format_basic_type">basic</a>,
651 <a href="#format_derived_type">derived</a>
652 or <a href="#format_composite_type">composite</a> type descriptors, each
653 representing a field member of the structure or union.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000654
Jim Laskey4a9df242006-08-21 21:21:06 +0000655<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
Bill Wendling48839d92009-05-17 05:52:39 +0000656 provide information about base classes, static members and member
657 functions. If a member is a <a href="#format_derived_type">derived type
658 descriptor</a> and has a tag of <tt>DW_TAG_inheritance</tt>, then the type
659 represents a base class. If the member of is
660 a <a href="#format_global_variables">global variable descriptor</a> then it
661 represents a static member. And, if the member is
662 a <a href="#format_subprograms">subprogram descriptor</a> then it represents
663 a member function. For static members and member
664 functions, <tt>getName()</tt> returns the members link or the C++ mangled
665 name. <tt>getDisplayName()</tt> the simplied version of the name.</p>
Jim Laskey4a9df242006-08-21 21:21:06 +0000666
Bill Wendling48839d92009-05-17 05:52:39 +0000667<p>The first member of subroutine (tag = <tt>DW_TAG_subroutine_type</tt>) type
668 elements is the return type for the subroutine. The remaining elements are
669 the formal arguments to the subroutine.</p>
Jim Laskey094ee722006-06-20 21:13:20 +0000670
Jim Laskeycec12a52006-03-14 18:08:46 +0000671<p><a href="#format_composite_type">Composite type</a> location can be
Bill Wendling48839d92009-05-17 05:52:39 +0000672 determined from the compile unit and line number. The size, alignment and
673 offset are expressed in bits and can be 64 bit values. The alignment is used
674 to round the offset when embedded in
675 a <a href="#format_composite_type">composite type</a> (as an example, to keep
676 float doubles on 64 bit boundaries.) The offset is the bit offset if embedded
677 in a <a href="#format_composite_type">composite type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000678
679</div>
680
681<!-- ======================================================================= -->
682<div class="doc_subsubsection">
683 <a name="format_subrange">Subrange descriptors</a>
684</div>
685
686<div class="doc_text">
687
Bill Wendling48839d92009-05-17 05:52:39 +0000688<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000689<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000690%<a href="#format_subrange">llvm.dbg.subrange.type</a> = type {
691 i32, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
692 i64, ;; Low value
693 i64 ;; High value
694}
Jim Laskeycec12a52006-03-14 18:08:46 +0000695</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000696</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000697
698<p>These descriptors are used to define ranges of array subscripts for an array
Bill Wendling48839d92009-05-17 05:52:39 +0000699 <a href="#format_composite_type">composite type</a>. The low value defines
700 the lower bounds typically zero for C/C++. The high value is the upper
701 bounds. Values are 64 bit. High - low + 1 is the size of the array. If low
702 == high the array will be unbounded.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000703
704</div>
705
706<!-- ======================================================================= -->
707<div class="doc_subsubsection">
708 <a name="format_enumeration">Enumerator descriptors</a>
709</div>
710
711<div class="doc_text">
712
Bill Wendling48839d92009-05-17 05:52:39 +0000713<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000714<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000715!6 = metadata !{
716 i32, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
717 ;; (DW_TAG_enumerator)
718 metadata, ;; Name
719 i64 ;; Value
Bill Wendling48839d92009-05-17 05:52:39 +0000720}
Jim Laskeycec12a52006-03-14 18:08:46 +0000721</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000722</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000723
Bill Wendling48839d92009-05-17 05:52:39 +0000724<p>These descriptors are used to define members of an
725 enumeration <a href="#format_composite_type">composite type</a>, it
726 associates the name to the value.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000727
728</div>
729
730<!-- ======================================================================= -->
Jim Laskey383e0092006-03-23 17:54:33 +0000731<div class="doc_subsubsection">
732 <a name="format_variables">Local variables</a>
733</div>
734
735<div class="doc_text">
Bill Wendling48839d92009-05-17 05:52:39 +0000736
737<div class="doc_code">
Jim Laskey383e0092006-03-23 17:54:33 +0000738<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000739!7 = metadata !{
740 i32, ;; Tag (see below)
741 metadata, ;; Context
742 metadata, ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000743 metadata, ;; Reference to file where defined
Devang Patele4b27562009-08-28 23:24:31 +0000744 i32, ;; Line number where defined
745 metadata ;; Type descriptor
Bill Wendling48839d92009-05-17 05:52:39 +0000746}
Jim Laskey383e0092006-03-23 17:54:33 +0000747</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000748</div>
Jim Laskey383e0092006-03-23 17:54:33 +0000749
750<p>These descriptors are used to define variables local to a sub program. The
Bill Wendling48839d92009-05-17 05:52:39 +0000751 value of the tag depends on the usage of the variable:</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000752
Bill Wendling48839d92009-05-17 05:52:39 +0000753<div class="doc_code">
Jim Laskey383e0092006-03-23 17:54:33 +0000754<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000755DW_TAG_auto_variable = 256
756DW_TAG_arg_variable = 257
757DW_TAG_return_variable = 258
Jim Laskey383e0092006-03-23 17:54:33 +0000758</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000759</div>
Jim Laskey383e0092006-03-23 17:54:33 +0000760
761<p>An auto variable is any variable declared in the body of the function. An
Bill Wendling48839d92009-05-17 05:52:39 +0000762 argument variable is any variable that appears as a formal argument to the
763 function. A return variable is used to track the result of a function and
764 has no source correspondent.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000765
Jim Laskey2d395d92006-03-24 09:20:27 +0000766<p>The context is either the subprogram or block where the variable is defined.
Bill Wendling48839d92009-05-17 05:52:39 +0000767 Name the source variable name. Compile unit and line indicate where the
768 variable was defined. Type descriptor defines the declared type of the
769 variable.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000770
771</div>
772
773<!-- ======================================================================= -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000774<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000775 <a name="format_common_intrinsics">Debugger intrinsic functions</a>
776</div>
777
778<div class="doc_text">
779
780<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
Bill Wendling48839d92009-05-17 05:52:39 +0000781 provide debug information at various points in generated code.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000782
783</div>
784
785<!-- ======================================================================= -->
786<div class="doc_subsubsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000787 <a name="format_common_declare">llvm.dbg.declare</a>
788</div>
789
790<div class="doc_text">
791<pre>
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000792 void %<a href="#format_common_declare">llvm.dbg.declare</a>({}*, metadata)
Jim Laskeycec12a52006-03-14 18:08:46 +0000793</pre>
794
Jim Laskey2d395d92006-03-24 09:20:27 +0000795<p>This intrinsic provides information about a local element (ex. variable.) The
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000796 first argument is the alloca for the variable, cast to a <tt>{}*</tt>. The
Bill Wendling48839d92009-05-17 05:52:39 +0000797 second argument is
798 the <tt>%<a href="#format_variables">llvm.dbg.variable</a></tt> containing
Devang Patele4b27562009-08-28 23:24:31 +0000799 the description of the variable. </p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000800
801</div>
802
803<!-- ======================================================================= -->
Victor Hernandez67a1a542010-01-11 22:53:48 +0000804<div class="doc_subsubsection">
805 <a name="format_common_value">llvm.dbg.value</a>
806</div>
807
808<div class="doc_text">
809<pre>
Dan Gohman3dfb3cf2010-05-28 17:07:41 +0000810 void %<a href="#format_common_value">llvm.dbg.value</a>(metadata, i64, metadata)
Victor Hernandez67a1a542010-01-11 22:53:48 +0000811</pre>
812
813<p>This intrinsic provides information when a user source variable is set to a
814 new value. The first argument is the new value (wrapped as metadata). The
815 second argument is the offset in the user source variable where the new value
816 is written. The third argument is
817 the <tt>%<a href="#format_variables">llvm.dbg.variable</a></tt> containing
818 the description of the user source variable. </p>
819
820</div>
821
822<!-- ======================================================================= -->
Jim Laskeycec12a52006-03-14 18:08:46 +0000823<div class="doc_subsection">
Chris Lattner8ff75902004-01-06 05:31:32 +0000824 <a name="format_common_lifetime">Object lifetimes and scoping</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000825</div>
826
827<div class="doc_text">
Bill Wendlingcf493b82009-12-01 00:53:11 +0000828<p>In many languages, the local variables in functions can have their lifetimes
829 or scopes limited to a subset of a function. In the C family of languages,
Bill Wendling48839d92009-05-17 05:52:39 +0000830 for example, variables are only live (readable and writable) within the
831 source block that they are defined in. In functional languages, values are
832 only readable after they have been defined. Though this is a very obvious
Bill Wendlingcf493b82009-12-01 00:53:11 +0000833 concept, it is non-trivial to model in LLVM, because it has no notion of
Bill Wendling48839d92009-05-17 05:52:39 +0000834 scoping in this sense, and does not want to be tied to a language's scoping
835 rules.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000836
Bill Wendlingcf493b82009-12-01 00:53:11 +0000837<p>In order to handle this, the LLVM debug format uses the metadata attached to
Nick Lewycky655fd032010-03-31 07:50:17 +0000838 llvm instructions to encode line number and scoping information. Consider
839 the following C fragment, for example:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000840
Bill Wendling48839d92009-05-17 05:52:39 +0000841<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000842<pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +00008431. void foo() {
Devang Patel744950d2009-11-25 23:28:01 +00008442. int X = 21;
8453. int Y = 22;
Chris Lattnerbdfb3392004-01-05 05:06:33 +00008464. {
Devang Patel744950d2009-11-25 23:28:01 +00008475. int Z = 23;
8486. Z = X;
Chris Lattnerbdfb3392004-01-05 05:06:33 +00008497. }
Devang Patel744950d2009-11-25 23:28:01 +00008508. X = Y;
Chris Lattnerbdfb3392004-01-05 05:06:33 +00008519. }
Misha Brukman82873732004-05-12 19:21:57 +0000852</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000853</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000854
Jim Laskeycec12a52006-03-14 18:08:46 +0000855<p>Compiled to LLVM, this function would be represented like this:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000856
Bill Wendling48839d92009-05-17 05:52:39 +0000857<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000858<pre>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000859define void @foo() nounwind ssp {
Jim Laskeycec12a52006-03-14 18:08:46 +0000860entry:
Bill Wendling02216ff2009-12-01 00:59:58 +0000861 %X = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
862 %Y = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
863 %Z = alloca i32, align 4 ; &lt;i32*&gt; [#uses=3]
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000864 %0 = bitcast i32* %X to {}* ; &lt;{}*&gt; [#uses=1]
865 call void @llvm.dbg.declare({}* %0, metadata !0), !dbg !7
Devang Patel744950d2009-11-25 23:28:01 +0000866 store i32 21, i32* %X, !dbg !8
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000867 %1 = bitcast i32* %Y to {}* ; &lt;{}*&gt; [#uses=1]
868 call void @llvm.dbg.declare({}* %1, metadata !9), !dbg !10
Devang Patel744950d2009-11-25 23:28:01 +0000869 store i32 22, i32* %Y, !dbg !11
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000870 %2 = bitcast i32* %Z to {}* ; &lt;{}*&gt; [#uses=1]
871 call void @llvm.dbg.declare({}* %2, metadata !12), !dbg !14
Devang Patel744950d2009-11-25 23:28:01 +0000872 store i32 23, i32* %Z, !dbg !15
Bill Wendling02216ff2009-12-01 00:59:58 +0000873 %tmp = load i32* %X, !dbg !16 ; &lt;i32&gt; [#uses=1]
874 %tmp1 = load i32* %Y, !dbg !16 ; &lt;i32&gt; [#uses=1]
875 %add = add nsw i32 %tmp, %tmp1, !dbg !16 ; &lt;i32&gt; [#uses=1]
Devang Patel744950d2009-11-25 23:28:01 +0000876 store i32 %add, i32* %Z, !dbg !16
Bill Wendling02216ff2009-12-01 00:59:58 +0000877 %tmp2 = load i32* %Y, !dbg !17 ; &lt;i32&gt; [#uses=1]
Devang Patel744950d2009-11-25 23:28:01 +0000878 store i32 %tmp2, i32* %X, !dbg !17
879 ret void, !dbg !18
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000880}
Devang Patel744950d2009-11-25 23:28:01 +0000881
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000882declare void @llvm.dbg.declare({}*, metadata) nounwind readnone
Devang Patel744950d2009-11-25 23:28:01 +0000883
884!0 = metadata !{i32 459008, metadata !1, metadata !"X",
885 metadata !3, i32 2, metadata !6}; [ DW_TAG_auto_variable ]
886!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
887!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo", metadata !"foo",
888 metadata !"foo", metadata !3, i32 1, metadata !4,
889 i1 false, i1 true}; [DW_TAG_subprogram ]
890!3 = metadata !{i32 458769, i32 0, i32 12, metadata !"foo.c",
891 metadata !"/private/tmp", metadata !"clang 1.1", i1 true,
892 i1 false, metadata !"", i32 0}; [DW_TAG_compile_unit ]
893!4 = metadata !{i32 458773, metadata !3, metadata !"", null, i32 0, i64 0, i64 0,
894 i64 0, i32 0, null, metadata !5, i32 0}; [DW_TAG_subroutine_type ]
895!5 = metadata !{null}
896!6 = metadata !{i32 458788, metadata !3, metadata !"int", metadata !3, i32 0,
897 i64 32, i64 32, i64 0, i32 0, i32 5}; [DW_TAG_base_type ]
898!7 = metadata !{i32 2, i32 7, metadata !1, null}
899!8 = metadata !{i32 2, i32 3, metadata !1, null}
900!9 = metadata !{i32 459008, metadata !1, metadata !"Y", metadata !3, i32 3,
901 metadata !6}; [ DW_TAG_auto_variable ]
902!10 = metadata !{i32 3, i32 7, metadata !1, null}
903!11 = metadata !{i32 3, i32 3, metadata !1, null}
904!12 = metadata !{i32 459008, metadata !13, metadata !"Z", metadata !3, i32 5,
905 metadata !6}; [ DW_TAG_auto_variable ]
906!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
907!14 = metadata !{i32 5, i32 9, metadata !13, null}
908!15 = metadata !{i32 5, i32 5, metadata !13, null}
909!16 = metadata !{i32 6, i32 5, metadata !13, null}
910!17 = metadata !{i32 8, i32 3, metadata !1, null}
911!18 = metadata !{i32 9, i32 1, metadata !2, null}
Misha Brukman82873732004-05-12 19:21:57 +0000912</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000913</div>
914
Bill Wendlingcf493b82009-12-01 00:53:11 +0000915<p>This example illustrates a few important details about LLVM debugging
916 information. In particular, it shows how the <tt>llvm.dbg.declare</tt>
917 intrinsic and location information, which are attached to an instruction,
918 are applied together to allow a debugger to analyze the relationship between
919 statements, variable definitions, and the code used to implement the
920 function.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000921
Bill Wendlingcf493b82009-12-01 00:53:11 +0000922<div class="doc_code">
Bill Wendling02216ff2009-12-01 00:59:58 +0000923<pre>
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000924call void @llvm.dbg.declare({}* %0, metadata !0), !dbg !7
Bill Wendlingcf493b82009-12-01 00:53:11 +0000925</pre>
926</div>
927
928<p>The first intrinsic
Devang Patel744950d2009-11-25 23:28:01 +0000929 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000930 encodes debugging information for the variable <tt>X</tt>. The metadata
931 <tt>!dbg !7</tt> attached to the intrinsic provides scope information for the
932 variable <tt>X</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000933
Bill Wendlingcf493b82009-12-01 00:53:11 +0000934<div class="doc_code">
935<pre>
936!7 = metadata !{i32 2, i32 7, metadata !1, null}
937!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
938!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo",
939 metadata !"foo", metadata !"foo", metadata !3, i32 1,
940 metadata !4, i1 false, i1 true}; [DW_TAG_subprogram ]
941</pre>
942</div>
943
944<p>Here <tt>!7</tt> is metadata providing location information. It has four
945 fields: line number, column number, scope, and original scope. The original
946 scope represents inline location if this instruction is inlined inside a
947 caller, and is null otherwise. In this example, scope is encoded by
Devang Patel744950d2009-11-25 23:28:01 +0000948 <tt>!1</tt>. <tt>!1</tt> represents a lexical block inside the scope
949 <tt>!2</tt>, where <tt>!2</tt> is a
Bill Wendlingcf493b82009-12-01 00:53:11 +0000950 <a href="#format_subprograms">subprogram descriptor</a>. This way the
951 location information attached to the intrinsics indicates that the
952 variable <tt>X</tt> is declared at line number 2 at a function level scope in
953 function <tt>foo</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000954
Devang Patel744950d2009-11-25 23:28:01 +0000955<p>Now lets take another example.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000956
Bill Wendlingcf493b82009-12-01 00:53:11 +0000957<div class="doc_code">
Bill Wendling02216ff2009-12-01 00:59:58 +0000958<pre>
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000959call void @llvm.dbg.declare({}* %2, metadata !12), !dbg !14
Bill Wendlingcf493b82009-12-01 00:53:11 +0000960</pre>
961</div>
962
963<p>The second intrinsic
Devang Patel744950d2009-11-25 23:28:01 +0000964 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000965 encodes debugging information for variable <tt>Z</tt>. The metadata
966 <tt>!dbg !14</tt> attached to the intrinsic provides scope information for
967 the variable <tt>Z</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000968
Bill Wendlingcf493b82009-12-01 00:53:11 +0000969<div class="doc_code">
970<pre>
971!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
972!14 = metadata !{i32 5, i32 9, metadata !13, null}
973</pre>
974</div>
Bill Wendling48839d92009-05-17 05:52:39 +0000975
John Criswellb34500f2010-03-17 15:01:50 +0000976<p>Here <tt>!14</tt> indicates that <tt>Z</tt> is declared at line number 5 and
Bill Wendlingcf493b82009-12-01 00:53:11 +0000977 column number 9 inside of lexical scope <tt>!13</tt>. The lexical scope
978 itself resides inside of lexical scope <tt>!1</tt> described above.</p>
979
980<p>The scope information attached with each instruction provides a
981 straightforward way to find instructions covered by a scope.</p>
982
Bill Wendling48839d92009-05-17 05:52:39 +0000983</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000984
985<!-- *********************************************************************** -->
986<div class="doc_section">
Chris Lattner8ff75902004-01-06 05:31:32 +0000987 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000988</div>
Misha Brukman94218a72004-12-09 20:27:37 +0000989<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000990
991<div class="doc_text">
992
Misha Brukman82873732004-05-12 19:21:57 +0000993<p>The C and C++ front-ends represent information about the program in a format
Bill Wendling48839d92009-05-17 05:52:39 +0000994 that is effectively identical
995 to <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3.0</a> in
996 terms of information content. This allows code generators to trivially
997 support native debuggers by generating standard dwarf information, and
998 contains enough information for non-dwarf targets to translate it as
999 needed.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +00001000
Jim Laskeycec12a52006-03-14 18:08:46 +00001001<p>This section describes the forms used to represent C and C++ programs. Other
Bill Wendling48839d92009-05-17 05:52:39 +00001002 languages could pattern themselves after this (which itself is tuned to
1003 representing programs in the same way that DWARF 3 does), or they could
1004 choose to provide completely different forms if they don't fit into the DWARF
1005 model. As support for debugging information gets added to the various LLVM
1006 source-language front-ends, the information used should be documented
1007 here.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +00001008
Jim Laskeycec12a52006-03-14 18:08:46 +00001009<p>The following sections provide examples of various C/C++ constructs and the
Bill Wendling48839d92009-05-17 05:52:39 +00001010 debug information that would best describe those constructs.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001011
Chris Lattnerbdfb3392004-01-05 05:06:33 +00001012</div>
1013
1014<!-- ======================================================================= -->
1015<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +00001016 <a name="ccxx_compile_units">C/C++ source file information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +00001017</div>
1018
1019<div class="doc_text">
Chris Lattnerbdfb3392004-01-05 05:06:33 +00001020
Bill Wendling48839d92009-05-17 05:52:39 +00001021<p>Given the source files <tt>MySource.cpp</tt> and <tt>MyHeader.h</tt> located
1022 in the directory <tt>/Users/mine/sources</tt>, the following code:</p>
Chris Lattner8ff75902004-01-06 05:31:32 +00001023
Bill Wendling48839d92009-05-17 05:52:39 +00001024<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001025<pre>
1026#include "MyHeader.h"
Chris Lattner8ff75902004-01-06 05:31:32 +00001027
Jim Laskeycec12a52006-03-14 18:08:46 +00001028int main(int argc, char *argv[]) {
1029 return 0;
1030}
1031</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001032</div>
Chris Lattner8ff75902004-01-06 05:31:32 +00001033
Misha Brukman96e00812008-12-16 02:54:22 +00001034<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001035
Bill Wendling48839d92009-05-17 05:52:39 +00001036<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001037<pre>
1038...
1039;;
Devang Patel4b945502010-03-09 00:44:10 +00001040;; Define the compile unit for the main source file "/Users/mine/sources/MySource.cpp".
Jim Laskeycec12a52006-03-14 18:08:46 +00001041;;
Devang Patel4b945502010-03-09 00:44:10 +00001042!2 = metadata !{
1043 i32 524305, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001044 i32 0, ;; Unused
1045 i32 4, ;; Language Id
1046 metadata !"MySource.cpp",
1047 metadata !"/Users/mine/sources",
1048 metadata !"4.2.1 (Based on Apple Inc. build 5649) (LLVM build 00)",
1049 i1 true, ;; Main Compile Unit
1050 i1 false, ;; Optimized compile unit
1051 metadata !"", ;; Compiler flags
1052 i32 0} ;; Runtime version
1053
Jim Laskeycec12a52006-03-14 18:08:46 +00001054;;
Devang Patel4b945502010-03-09 00:44:10 +00001055;; Define the file for the file "/Users/mine/sources/MySource.cpp".
Jim Laskeycec12a52006-03-14 18:08:46 +00001056;;
Devang Patele4b27562009-08-28 23:24:31 +00001057!1 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001058 i32 524329, ;; Tag
1059 metadata !"MySource.cpp",
Devang Patele4b27562009-08-28 23:24:31 +00001060 metadata !"/Users/mine/sources",
Devang Patel9fea9c22010-07-13 16:53:20 +00001061 metadata !2 ;; Compile unit
Devang Patel4b945502010-03-09 00:44:10 +00001062}
1063
1064;;
1065;; Define the file for the file "/Users/mine/sources/Myheader.h"
1066;;
1067!3 = metadata !{
1068 i32 524329, ;; Tag
1069 metadata !"Myheader.h"
1070 metadata !"/Users/mine/sources",
Devang Patel9fea9c22010-07-13 16:53:20 +00001071 metadata !2 ;; Compile unit
Devang Patel4b945502010-03-09 00:44:10 +00001072}
Jim Laskeycec12a52006-03-14 18:08:46 +00001073
Jim Laskeycec12a52006-03-14 18:08:46 +00001074...
1075</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001076</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001077
Devang Pateld98ec5f2010-03-26 19:08:36 +00001078<p>llvm::Instruction provides easy access to metadata attached with an
1079instruction. One can extract line number information encoded in LLVM IR
1080using <tt>Instruction::getMetadata()</tt> and
1081<tt>DILocation::getLineNumber()</tt>.
1082<pre>
1083 if (MDNode *N = I->getMetadata("dbg")) { // Here I is an LLVM instruction
1084 DILocation Loc(N); // DILocation is in DebugInfo.h
1085 unsigned Line = Loc.getLineNumber();
1086 StringRef File = Loc.getFilename();
1087 StringRef Dir = Loc.getDirectory();
1088 }
1089</pre>
Chris Lattner8ff75902004-01-06 05:31:32 +00001090</div>
1091
1092<!-- ======================================================================= -->
1093<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +00001094 <a name="ccxx_global_variable">C/C++ global variable information</a>
Chris Lattner8ff75902004-01-06 05:31:32 +00001095</div>
1096
1097<div class="doc_text">
Jim Laskeycec12a52006-03-14 18:08:46 +00001098
Misha Brukman96e00812008-12-16 02:54:22 +00001099<p>Given an integer global variable declared as follows:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001100
Bill Wendling48839d92009-05-17 05:52:39 +00001101<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001102<pre>
1103int MyGlobal = 100;
1104</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001105</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001106
Misha Brukman96e00812008-12-16 02:54:22 +00001107<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001108
Bill Wendling48839d92009-05-17 05:52:39 +00001109<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001110<pre>
1111;;
Jim Laskeycec12a52006-03-14 18:08:46 +00001112;; Define the global itself.
1113;;
1114%MyGlobal = global int 100
1115...
1116;;
Devang Patele4b27562009-08-28 23:24:31 +00001117;; List of debug info of globals
Jim Laskeycec12a52006-03-14 18:08:46 +00001118;;
Devang Patele4b27562009-08-28 23:24:31 +00001119!llvm.dbg.gv = !{!0}
Jim Laskeycec12a52006-03-14 18:08:46 +00001120
1121;;
1122;; Define the global variable descriptor. Note the reference to the global
1123;; variable anchor and the global variable itself.
1124;;
Devang Patele4b27562009-08-28 23:24:31 +00001125!0 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001126 i32 524340, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001127 i32 0, ;; Unused
1128 metadata !1, ;; Context
1129 metadata !"MyGlobal", ;; Name
1130 metadata !"MyGlobal", ;; Display Name
1131 metadata !"MyGlobal", ;; Linkage Name
Devang Patel4b945502010-03-09 00:44:10 +00001132 metadata !3, ;; Compile Unit
Devang Patele4b27562009-08-28 23:24:31 +00001133 i32 1, ;; Line Number
Devang Patel4b945502010-03-09 00:44:10 +00001134 metadata !4, ;; Type
Devang Patele4b27562009-08-28 23:24:31 +00001135 i1 false, ;; Is a local variable
1136 i1 true, ;; Is this a definition
1137 i32* @MyGlobal ;; The global variable
1138}
1139
Jim Laskeycec12a52006-03-14 18:08:46 +00001140;;
1141;; Define the basic type of 32 bit signed integer. Note that since int is an
1142;; intrinsic type the source file is NULL and line 0.
1143;;
Devang Patel4b945502010-03-09 00:44:10 +00001144!4 = metadata !{
1145 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001146 metadata !1, ;; Context
1147 metadata !"int", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001148 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001149 i32 0, ;; Line number
1150 i64 32, ;; Size in Bits
1151 i64 32, ;; Align in Bits
1152 i64 0, ;; Offset in Bits
1153 i32 0, ;; Flags
1154 i32 5 ;; Encoding
1155}
Jim Laskeycec12a52006-03-14 18:08:46 +00001156
Jim Laskeycec12a52006-03-14 18:08:46 +00001157</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001158</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001159
Chris Lattner8ff75902004-01-06 05:31:32 +00001160</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +00001161
Jim Laskeycec12a52006-03-14 18:08:46 +00001162<!-- ======================================================================= -->
1163<div class="doc_subsection">
1164 <a name="ccxx_subprogram">C/C++ function information</a>
1165</div>
1166
1167<div class="doc_text">
1168
Misha Brukman96e00812008-12-16 02:54:22 +00001169<p>Given a function declared as follows:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001170
Bill Wendling48839d92009-05-17 05:52:39 +00001171<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001172<pre>
1173int main(int argc, char *argv[]) {
1174 return 0;
1175}
1176</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001177</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001178
Misha Brukman96e00812008-12-16 02:54:22 +00001179<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001180
Bill Wendling48839d92009-05-17 05:52:39 +00001181<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001182<pre>
1183;;
Jim Laskeycec12a52006-03-14 18:08:46 +00001184;; Define the anchor for subprograms. Note that the second field of the
1185;; anchor is 46, which is the same as the tag for subprograms
1186;; (46 = DW_TAG_subprogram.)
1187;;
Devang Patel4b945502010-03-09 00:44:10 +00001188!6 = metadata !{
1189 i32 524334, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001190 i32 0, ;; Unused
1191 metadata !1, ;; Context
1192 metadata !"main", ;; Name
1193 metadata !"main", ;; Display name
1194 metadata !"main", ;; Linkage name
Devang Patel4b945502010-03-09 00:44:10 +00001195 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001196 i32 1, ;; Line number
Devang Patel4b945502010-03-09 00:44:10 +00001197 metadata !4, ;; Type
Devang Patele4b27562009-08-28 23:24:31 +00001198 i1 false, ;; Is local
1199 i1 true ;; Is definition
1200}
Jim Laskeycec12a52006-03-14 18:08:46 +00001201;;
1202;; Define the subprogram itself.
1203;;
Devang Patele4b27562009-08-28 23:24:31 +00001204define i32 @main(i32 %argc, i8** %argv) {
Jim Laskeycec12a52006-03-14 18:08:46 +00001205...
1206}
1207</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001208</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001209
1210</div>
1211
1212<!-- ======================================================================= -->
1213<div class="doc_subsection">
1214 <a name="ccxx_basic_types">C/C++ basic types</a>
1215</div>
1216
1217<div class="doc_text">
1218
Misha Brukman96e00812008-12-16 02:54:22 +00001219<p>The following are the basic type descriptors for C/C++ core types:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001220
1221</div>
1222
1223<!-- ======================================================================= -->
1224<div class="doc_subsubsection">
1225 <a name="ccxx_basic_type_bool">bool</a>
1226</div>
1227
1228<div class="doc_text">
1229
Bill Wendling48839d92009-05-17 05:52:39 +00001230<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001231<pre>
Devang Patele4b27562009-08-28 23:24:31 +00001232!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001233 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001234 metadata !1, ;; Context
1235 metadata !"bool", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001236 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001237 i32 0, ;; Line number
1238 i64 8, ;; Size in Bits
1239 i64 8, ;; Align in Bits
1240 i64 0, ;; Offset in Bits
1241 i32 0, ;; Flags
1242 i32 2 ;; Encoding
1243}
Jim Laskeycec12a52006-03-14 18:08:46 +00001244</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001245</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001246
1247</div>
1248
1249<!-- ======================================================================= -->
1250<div class="doc_subsubsection">
1251 <a name="ccxx_basic_char">char</a>
1252</div>
1253
1254<div class="doc_text">
1255
Bill Wendling48839d92009-05-17 05:52:39 +00001256<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001257<pre>
Devang Patele4b27562009-08-28 23:24:31 +00001258!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001259 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001260 metadata !1, ;; Context
1261 metadata !"char", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001262 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001263 i32 0, ;; Line number
1264 i64 8, ;; Size in Bits
1265 i64 8, ;; Align in Bits
1266 i64 0, ;; Offset in Bits
1267 i32 0, ;; Flags
1268 i32 6 ;; Encoding
1269}
Jim Laskeycec12a52006-03-14 18:08:46 +00001270</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001271</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001272
1273</div>
1274
1275<!-- ======================================================================= -->
1276<div class="doc_subsubsection">
1277 <a name="ccxx_basic_unsigned_char">unsigned char</a>
1278</div>
1279
1280<div class="doc_text">
1281
Bill Wendling48839d92009-05-17 05:52:39 +00001282<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001283<pre>
Devang Patele4b27562009-08-28 23:24:31 +00001284!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001285 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001286 metadata !1, ;; Context
1287 metadata !"unsigned char",
Devang Patel4b945502010-03-09 00:44:10 +00001288 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001289 i32 0, ;; Line number
1290 i64 8, ;; Size in Bits
1291 i64 8, ;; Align in Bits
1292 i64 0, ;; Offset in Bits
1293 i32 0, ;; Flags
1294 i32 8 ;; Encoding
1295}
Jim Laskeycec12a52006-03-14 18:08:46 +00001296</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001297</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001298
1299</div>
1300
1301<!-- ======================================================================= -->
1302<div class="doc_subsubsection">
1303 <a name="ccxx_basic_short">short</a>
1304</div>
1305
1306<div class="doc_text">
1307
Bill Wendling48839d92009-05-17 05:52:39 +00001308<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001309<pre>
Devang Patele4b27562009-08-28 23:24:31 +00001310!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001311 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001312 metadata !1, ;; Context
1313 metadata !"short int",
Devang Patel4b945502010-03-09 00:44:10 +00001314 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001315 i32 0, ;; Line number
1316 i64 16, ;; Size in Bits
1317 i64 16, ;; Align in Bits
1318 i64 0, ;; Offset in Bits
1319 i32 0, ;; Flags
1320 i32 5 ;; Encoding
1321}
Jim Laskeycec12a52006-03-14 18:08:46 +00001322</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001323</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001324
1325</div>
1326
1327<!-- ======================================================================= -->
1328<div class="doc_subsubsection">
1329 <a name="ccxx_basic_unsigned_short">unsigned short</a>
1330</div>
1331
1332<div class="doc_text">
1333
Bill Wendling48839d92009-05-17 05:52:39 +00001334<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001335<pre>
Devang Patele4b27562009-08-28 23:24:31 +00001336!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001337 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001338 metadata !1, ;; Context
1339 metadata !"short unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +00001340 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001341 i32 0, ;; Line number
1342 i64 16, ;; Size in Bits
1343 i64 16, ;; Align in Bits
1344 i64 0, ;; Offset in Bits
1345 i32 0, ;; Flags
1346 i32 7 ;; Encoding
1347}
Jim Laskeycec12a52006-03-14 18:08:46 +00001348</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001349</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001350
1351</div>
1352
1353<!-- ======================================================================= -->
1354<div class="doc_subsubsection">
1355 <a name="ccxx_basic_int">int</a>
1356</div>
1357
1358<div class="doc_text">
1359
Bill Wendling48839d92009-05-17 05:52:39 +00001360<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001361<pre>
Devang Patele4b27562009-08-28 23:24:31 +00001362!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001363 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001364 metadata !1, ;; Context
1365 metadata !"int", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001366 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001367 i32 0, ;; Line number
1368 i64 32, ;; Size in Bits
1369 i64 32, ;; Align in Bits
1370 i64 0, ;; Offset in Bits
1371 i32 0, ;; Flags
1372 i32 5 ;; Encoding
1373}
Bill Wendling48839d92009-05-17 05:52:39 +00001374</pre></div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001375
1376</div>
1377
1378<!-- ======================================================================= -->
1379<div class="doc_subsubsection">
1380 <a name="ccxx_basic_unsigned_int">unsigned int</a>
1381</div>
1382
1383<div class="doc_text">
1384
Bill Wendling48839d92009-05-17 05:52:39 +00001385<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001386<pre>
Devang Patele4b27562009-08-28 23:24:31 +00001387!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001388 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001389 metadata !1, ;; Context
1390 metadata !"unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +00001391 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001392 i32 0, ;; Line number
1393 i64 32, ;; Size in Bits
1394 i64 32, ;; Align in Bits
1395 i64 0, ;; Offset in Bits
1396 i32 0, ;; Flags
1397 i32 7 ;; Encoding
1398}
Jim Laskeycec12a52006-03-14 18:08:46 +00001399</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001400</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001401
1402</div>
1403
1404<!-- ======================================================================= -->
1405<div class="doc_subsubsection">
1406 <a name="ccxx_basic_long_long">long long</a>
1407</div>
1408
1409<div class="doc_text">
1410
Bill Wendling48839d92009-05-17 05:52:39 +00001411<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001412<pre>
Devang Patele4b27562009-08-28 23:24:31 +00001413!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001414 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001415 metadata !1, ;; Context
1416 metadata !"long long int",
Devang Patel4b945502010-03-09 00:44:10 +00001417 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001418 i32 0, ;; Line number
1419 i64 64, ;; Size in Bits
1420 i64 64, ;; Align in Bits
1421 i64 0, ;; Offset in Bits
1422 i32 0, ;; Flags
1423 i32 5 ;; Encoding
1424}
Jim Laskeycec12a52006-03-14 18:08:46 +00001425</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001426</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001427
1428</div>
1429
1430<!-- ======================================================================= -->
1431<div class="doc_subsubsection">
1432 <a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
1433</div>
1434
1435<div class="doc_text">
1436
Bill Wendling48839d92009-05-17 05:52:39 +00001437<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001438<pre>
Devang Patele4b27562009-08-28 23:24:31 +00001439!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001440 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001441 metadata !1, ;; Context
1442 metadata !"long long unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +00001443 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001444 i32 0, ;; Line number
1445 i64 64, ;; Size in Bits
1446 i64 64, ;; Align in Bits
1447 i64 0, ;; Offset in Bits
1448 i32 0, ;; Flags
1449 i32 7 ;; Encoding
1450}
Jim Laskeycec12a52006-03-14 18:08:46 +00001451</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001452</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001453
1454</div>
1455
1456<!-- ======================================================================= -->
1457<div class="doc_subsubsection">
1458 <a name="ccxx_basic_float">float</a>
1459</div>
1460
1461<div class="doc_text">
1462
Bill Wendling48839d92009-05-17 05:52:39 +00001463<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001464<pre>
Devang Patele4b27562009-08-28 23:24:31 +00001465!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001466 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001467 metadata !1, ;; Context
1468 metadata !"float",
Devang Patel4b945502010-03-09 00:44:10 +00001469 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001470 i32 0, ;; Line number
1471 i64 32, ;; Size in Bits
1472 i64 32, ;; Align in Bits
1473 i64 0, ;; Offset in Bits
1474 i32 0, ;; Flags
1475 i32 4 ;; Encoding
1476}
Jim Laskeycec12a52006-03-14 18:08:46 +00001477</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001478</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001479
1480</div>
1481
1482<!-- ======================================================================= -->
1483<div class="doc_subsubsection">
1484 <a name="ccxx_basic_double">double</a>
1485</div>
1486
1487<div class="doc_text">
1488
Bill Wendling48839d92009-05-17 05:52:39 +00001489<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001490<pre>
Devang Patele4b27562009-08-28 23:24:31 +00001491!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001492 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001493 metadata !1, ;; Context
1494 metadata !"double",;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001495 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001496 i32 0, ;; Line number
1497 i64 64, ;; Size in Bits
1498 i64 64, ;; Align in Bits
1499 i64 0, ;; Offset in Bits
1500 i32 0, ;; Flags
1501 i32 4 ;; Encoding
1502}
Jim Laskeycec12a52006-03-14 18:08:46 +00001503</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001504</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001505
1506</div>
1507
1508<!-- ======================================================================= -->
1509<div class="doc_subsection">
1510 <a name="ccxx_derived_types">C/C++ derived types</a>
1511</div>
1512
1513<div class="doc_text">
1514
Misha Brukman96e00812008-12-16 02:54:22 +00001515<p>Given the following as an example of C/C++ derived type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001516
Bill Wendling48839d92009-05-17 05:52:39 +00001517<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001518<pre>
1519typedef const int *IntPtr;
1520</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001521</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001522
Misha Brukman96e00812008-12-16 02:54:22 +00001523<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001524
Bill Wendling48839d92009-05-17 05:52:39 +00001525<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001526<pre>
1527;;
1528;; Define the typedef "IntPtr".
1529;;
Devang Patele4b27562009-08-28 23:24:31 +00001530!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001531 i32 524310, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001532 metadata !1, ;; Context
1533 metadata !"IntPtr", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001534 metadata !3, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001535 i32 0, ;; Line number
1536 i64 0, ;; Size in bits
1537 i64 0, ;; Align in bits
1538 i64 0, ;; Offset in bits
1539 i32 0, ;; Flags
1540 metadata !4 ;; Derived From type
1541}
Jim Laskeycec12a52006-03-14 18:08:46 +00001542
1543;;
1544;; Define the pointer type.
1545;;
Devang Patele4b27562009-08-28 23:24:31 +00001546!4 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001547 i32 524303, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001548 metadata !1, ;; Context
1549 metadata !"", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001550 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001551 i32 0, ;; Line number
1552 i64 64, ;; Size in bits
1553 i64 64, ;; Align in bits
1554 i64 0, ;; Offset in bits
1555 i32 0, ;; Flags
1556 metadata !5 ;; Derived From type
1557}
Jim Laskeycec12a52006-03-14 18:08:46 +00001558;;
1559;; Define the const type.
1560;;
Devang Patele4b27562009-08-28 23:24:31 +00001561!5 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001562 i32 524326, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001563 metadata !1, ;; Context
1564 metadata !"", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001565 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001566 i32 0, ;; Line number
1567 i64 32, ;; Size in bits
1568 i64 32, ;; Align in bits
1569 i64 0, ;; Offset in bits
1570 i32 0, ;; Flags
1571 metadata !6 ;; Derived From type
1572}
Jim Laskeycec12a52006-03-14 18:08:46 +00001573;;
1574;; Define the int type.
1575;;
Devang Patele4b27562009-08-28 23:24:31 +00001576!6 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001577 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001578 metadata !1, ;; Context
1579 metadata !"int", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001580 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001581 i32 0, ;; Line number
1582 i64 32, ;; Size in bits
1583 i64 32, ;; Align in bits
1584 i64 0, ;; Offset in bits
1585 i32 0, ;; Flags
1586 5 ;; Encoding
1587}
Jim Laskeycec12a52006-03-14 18:08:46 +00001588</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001589</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001590
1591</div>
1592
1593<!-- ======================================================================= -->
1594<div class="doc_subsection">
1595 <a name="ccxx_composite_types">C/C++ struct/union types</a>
1596</div>
1597
1598<div class="doc_text">
1599
Misha Brukman96e00812008-12-16 02:54:22 +00001600<p>Given the following as an example of C/C++ struct type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001601
Bill Wendling48839d92009-05-17 05:52:39 +00001602<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001603<pre>
1604struct Color {
1605 unsigned Red;
1606 unsigned Green;
1607 unsigned Blue;
1608};
1609</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001610</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001611
Misha Brukman96e00812008-12-16 02:54:22 +00001612<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001613
Bill Wendling48839d92009-05-17 05:52:39 +00001614<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001615<pre>
1616;;
1617;; Define basic type for unsigned int.
1618;;
Devang Patele4b27562009-08-28 23:24:31 +00001619!5 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001620 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001621 metadata !1, ;; Context
1622 metadata !"unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +00001623 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001624 i32 0, ;; Line number
1625 i64 32, ;; Size in Bits
1626 i64 32, ;; Align in Bits
1627 i64 0, ;; Offset in Bits
1628 i32 0, ;; Flags
1629 i32 7 ;; Encoding
1630}
Jim Laskeycec12a52006-03-14 18:08:46 +00001631;;
1632;; Define composite type for struct Color.
1633;;
Devang Patele4b27562009-08-28 23:24:31 +00001634!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001635 i32 524307, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001636 metadata !1, ;; Context
1637 metadata !"Color", ;; Name
1638 metadata !1, ;; Compile unit
1639 i32 1, ;; Line number
1640 i64 96, ;; Size in bits
1641 i64 32, ;; Align in bits
1642 i64 0, ;; Offset in bits
1643 i32 0, ;; Flags
1644 null, ;; Derived From
1645 metadata !3, ;; Elements
1646 i32 0 ;; Runtime Language
1647}
Jim Laskeycec12a52006-03-14 18:08:46 +00001648
1649;;
1650;; Define the Red field.
1651;;
Devang Patele4b27562009-08-28 23:24:31 +00001652!4 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001653 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001654 metadata !1, ;; Context
1655 metadata !"Red", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001656 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001657 i32 2, ;; Line number
1658 i64 32, ;; Size in bits
1659 i64 32, ;; Align in bits
1660 i64 0, ;; Offset in bits
1661 i32 0, ;; Flags
1662 metadata !5 ;; Derived From type
1663}
Jim Laskeycec12a52006-03-14 18:08:46 +00001664
1665;;
1666;; Define the Green field.
1667;;
Devang Patele4b27562009-08-28 23:24:31 +00001668!6 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001669 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001670 metadata !1, ;; Context
1671 metadata !"Green", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001672 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001673 i32 3, ;; Line number
1674 i64 32, ;; Size in bits
1675 i64 32, ;; Align in bits
1676 i64 32, ;; Offset in bits
1677 i32 0, ;; Flags
1678 metadata !5 ;; Derived From type
1679}
Jim Laskeycec12a52006-03-14 18:08:46 +00001680
1681;;
1682;; Define the Blue field.
1683;;
Devang Patele4b27562009-08-28 23:24:31 +00001684!7 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001685 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001686 metadata !1, ;; Context
1687 metadata !"Blue", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001688 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001689 i32 4, ;; Line number
1690 i64 32, ;; Size in bits
1691 i64 32, ;; Align in bits
1692 i64 64, ;; Offset in bits
1693 i32 0, ;; Flags
1694 metadata !5 ;; Derived From type
1695}
Jim Laskeycec12a52006-03-14 18:08:46 +00001696
1697;;
1698;; Define the array of fields used by the composite type Color.
1699;;
Devang Patele4b27562009-08-28 23:24:31 +00001700!3 = metadata !{metadata !4, metadata !6, metadata !7}
Jim Laskeycec12a52006-03-14 18:08:46 +00001701</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001702</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001703
1704</div>
1705
1706<!-- ======================================================================= -->
1707<div class="doc_subsection">
1708 <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
1709</div>
1710
1711<div class="doc_text">
1712
Misha Brukman96e00812008-12-16 02:54:22 +00001713<p>Given the following as an example of C/C++ enumeration type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001714
Bill Wendling48839d92009-05-17 05:52:39 +00001715<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001716<pre>
1717enum Trees {
1718 Spruce = 100,
1719 Oak = 200,
1720 Maple = 300
1721};
1722</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001723</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001724
Misha Brukman96e00812008-12-16 02:54:22 +00001725<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +00001726
Bill Wendling48839d92009-05-17 05:52:39 +00001727<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +00001728<pre>
1729;;
1730;; Define composite type for enum Trees
1731;;
Devang Patele4b27562009-08-28 23:24:31 +00001732!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +00001733 i32 524292, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +00001734 metadata !1, ;; Context
1735 metadata !"Trees", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +00001736 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +00001737 i32 1, ;; Line number
1738 i64 32, ;; Size in bits
1739 i64 32, ;; Align in bits
1740 i64 0, ;; Offset in bits
1741 i32 0, ;; Flags
1742 null, ;; Derived From type
1743 metadata !3, ;; Elements
1744 i32 0 ;; Runtime language
1745}
Devang Patel2a610c72009-08-25 05:24:07 +00001746
Devang Patel82459882009-08-26 05:01:18 +00001747;;
1748;; Define the array of enumerators used by composite type Trees.
1749;;
Devang Patele4b27562009-08-28 23:24:31 +00001750!3 = metadata !{metadata !4, metadata !5, metadata !6}
1751
1752;;
1753;; Define Spruce enumerator.
1754;;
Devang Patel4b945502010-03-09 00:44:10 +00001755!4 = metadata !{i32 524328, metadata !"Spruce", i64 100}
Devang Patele4b27562009-08-28 23:24:31 +00001756
1757;;
1758;; Define Oak enumerator.
1759;;
Devang Patel4b945502010-03-09 00:44:10 +00001760!5 = metadata !{i32 524328, metadata !"Oak", i64 200}
Devang Patele4b27562009-08-28 23:24:31 +00001761
1762;;
1763;; Define Maple enumerator.
1764;;
Devang Patel4b945502010-03-09 00:44:10 +00001765!6 = metadata !{i32 524328, metadata !"Maple", i64 300}
Devang Patele4b27562009-08-28 23:24:31 +00001766
Jim Laskeycec12a52006-03-14 18:08:46 +00001767</pre>
Bill Wendling48839d92009-05-17 05:52:39 +00001768</div>
Jim Laskeycec12a52006-03-14 18:08:46 +00001769
1770</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +00001771
1772<!-- *********************************************************************** -->
Misha Brukman82873732004-05-12 19:21:57 +00001773
Chris Lattnerbdfb3392004-01-05 05:06:33 +00001774<hr>
Misha Brukman82873732004-05-12 19:21:57 +00001775<address>
1776 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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Misha Brukman82873732004-05-12 19:21:57 +00001780
1781 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +00001782 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Chris Lattnerbdfb3392004-01-05 05:06:33 +00001783 Last modified: $Date$
Misha Brukman82873732004-05-12 19:21:57 +00001784</address>
Chris Lattnerbdfb3392004-01-05 05:06:33 +00001785
1786</body>
1787</html>