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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 55202eaf6299c8be2aaa97697c6dfccbbbfcc81c / . / docs / SourceLevelDebugging.html
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Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6 <title>Source Level Debugging with LLVM</title>
7 <link rel="stylesheet" href="llvm.css" type="text/css">
8</head>
9<body>
10
11<div class="doc_title">Source Level Debugging with LLVM</div>
12
13<table class="layout" style="width:100%">
14 <tr class="layout">
15 <td class="left">
16<ul>
17 <li><a href="#introduction">Introduction</a>
18 <ol>
19 <li><a href="#phil">Philosophy behind LLVM debugging information</a></li>
20 <li><a href="#consumers">Debug information consumers</a></li>
21 <li><a href="#debugopt">Debugging optimized code</a></li>
22 </ol></li>
23 <li><a href="#format">Debugging information format</a>
24 <ol>
25 <li><a href="#debug_info_descriptors">Debug information descriptors</a>
26 <ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]27 <li><a href="#format_compile_units">Compile unit descriptors</a></li>
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]28 <li><a href="#format_files">File descriptors</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]29 <li><a href="#format_global_variables">Global variable descriptors</a></li>
30 <li><a href="#format_subprograms">Subprogram descriptors</a></li>
31 <li><a href="#format_blocks">Block descriptors</a></li>
32 <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>
37 <li><a href="#format_variables">Local variables</a></li>
38 </ul></li>
39 <li><a href="#format_common_intrinsics">Debugger intrinsic functions</a>
40 <ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]41 <li><a href="#format_common_declare">llvm.dbg.declare</a></li>
Victor Hernandez128bf422010-01-11 22:53:48 +0000[diff] [blame]42 <li><a href="#format_common_value">llvm.dbg.value</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]43 </ul></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]44 </ol></li>
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]45 <li><a href="#format_common_lifetime">Object lifetimes and scoping</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]46 <li><a href="#ccxx_frontend">C/C++ front-end specific debug information</a>
47 <ol>
48 <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>
55 </ol></li>
56</ul>
57</td>
58<td class="right">
59<img src="img/venusflytrap.jpg" alt="A leafy and green bug eater" width="247"
60height="369">
61</td>
62</tr></table>
63
64<div class="doc_author">
65 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
66 and <a href="mailto:jlaskey@mac.com">Jim Laskey</a></p>
67</div>
68
69
70<!-- *********************************************************************** -->
71<div class="doc_section"><a name="introduction">Introduction</a></div>
72<!-- *********************************************************************** -->
73
74<div class="doc_text">
75
76<p>This document is the central repository for all information pertaining to
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]77 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 Lattner990e7652009-07-18 21:47:15 +0000[diff] [blame]80 Further, this document provides specific examples of what debug information
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]81 for C/C++.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]82
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
92<p>The idea of the LLVM debugging information is to capture how the important
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]93 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]96
97<ul>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]98 <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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]101
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]102 <li>LLVM optimizations should interact in <a href="#debugopt">well-defined and
103 easily described ways</a> with the debugging information.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]104
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]105 <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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]108
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]109 <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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]112
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]113 <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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]117</ul>
118
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]119<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 Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]122 description of the source-level program is maintained in LLVM metadata
123 in an <a href="#ccxx_frontend">implementation-defined format</a>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]124 (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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]127
128<p>When a program is being debugged, a debugger interacts with the user and
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]129 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]132
133</div>
134
135<!-- ======================================================================= -->
136<div class="doc_subsection">
137 <a name="consumers">Debug information consumers</a>
138</div>
139
140<div class="doc_text">
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]141
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]142<p>The role of debug information is to provide meta information normally
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]143 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]146
Chris Lattnerd961f272010-04-05 04:11:11 +0000[diff] [blame]147<p>Currently, debug information is consumed by DwarfDebug to produce dwarf
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]148 information used by the gdb debugger. Other targets could use the same
149 information to produce stabs or other debug forms.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]150
151<p>It would also be reasonable to use debug information to feed profiling tools
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]152 for analysis of generated code, or, tools for reconstructing the original
153 source from generated code.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]154
155<p>TODO - expound a bit more.</p>
156
157</div>
158
159<!-- ======================================================================= -->
160<div class="doc_subsection">
161 <a name="debugopt">Debugging optimized code</a>
162</div>
163
164<div class="doc_text">
165
166<p>An extremely high priority of LLVM debugging information is to make it
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]167 interact well with optimizations and analysis. In particular, the LLVM debug
168 information provides the following guarantees:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]169
170<ul>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]171 <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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]178
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]179 <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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]184
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]185 <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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]190
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]191 <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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]195
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]196 <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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]200</ul>
201
202<p>Basically, the debug information allows you to compile a program with
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]203 "<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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]210
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]211<p><a href="TestingGuide.html#quicktestsuite">LLVM test suite</a> provides a
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]212 framework to test optimizer's handling of debugging information. It can be
213 run like this:</p>
Devang Patel7717e542008-11-21 19:35:57 +0000[diff] [blame]214
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]222<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 Patel7717e542008-11-21 19:35:57 +0000[diff] [blame]226
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]227</div>
228
229<!-- *********************************************************************** -->
230<div class="doc_section">
231 <a name="format">Debugging information format</a>
232</div>
233<!-- *********************************************************************** -->
234
235<div class="doc_text">
236
237<p>LLVM debugging information has been carefully designed to make it possible
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]238 for the optimizer to optimize the program and debugging information without
239 necessarily having to know anything about debugging information. In
John Criswell5dacd082010-03-17 15:01:50 +0000[diff] [blame]240 particular, the use of metadata avoids duplicated debugging information from
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]241 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]244
245<p>To do this, most of the debugging information (descriptors for types,
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]246 variables, functions, source files, etc) is inserted by the language
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]247 front-end in the form of LLVM metadata. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]248
249<p>Debug information is designed to be agnostic about the target debugger and
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]250 debugging information representation (e.g. DWARF/Stabs/etc). It uses a
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]251 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]255
256<p>To provide basic functionality, the LLVM debugger does have to make some
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]257 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 Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]259 exist are <a href="#format_files">source files</a>,
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]260 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]263
264<p>This section of the documentation first describes the representation aspects
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]265 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]267
268</div>
269
270<!-- ======================================================================= -->
271<div class="doc_subsection">
272 <a name="debug_info_descriptors">Debug information descriptors</a>
273</div>
274
275<div class="doc_text">
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]276
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]277<p>In consideration of the complexity and volume of debug information, LLVM
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]278 provides a specification for well formed debug descriptors. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]279
280<p>Consumers of LLVM debug information expect the descriptors for program
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]281 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 Kramer5fb9d7e2009-10-12 14:46:08 +0000[diff] [blame]288 the range 0x1000 through 0x2000 (there is a defined enum DW_TAG_user_base =
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]289 0x1000.)</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]290
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]291<p>The fields of debug descriptors used internally by LLVM
Nick Lewycky30b67f92010-03-31 07:50:17 +0000[diff] [blame]292 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]294
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]295<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]296<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]297!1 = metadata !{
Nick Lewycky30b67f92010-03-31 07:50:17 +0000[diff] [blame]298 i32, ;; A tag
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]299 ...
300}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]301</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]302</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]303
304<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
Nick Lewycky30b67f92010-03-31 07:50:17 +0000[diff] [blame]305 <tt>i32</tt> containing a tag value identifying the content of the
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]306 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 Lewycky30b67f92010-03-31 07:50:17 +0000[diff] [blame]310 with the current debug version (LLVMDebugVersion = 8 &lt;&lt; 16 or 0x80000 or
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]311 524288.)</a></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]312
313<p>The details of the various descriptors follow.</p>
314
315</div>
316
317<!-- ======================================================================= -->
318<div class="doc_subsubsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]319 <a name="format_compile_units">Compile unit descriptors</a>
320</div>
321
322<div class="doc_text">
323
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]324<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]325<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]326!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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]338}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]339</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]340</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]341
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]342<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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]347
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]348<p>Compile unit descriptors provide the root context for objects declared in a
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]349 specific compilation unit. File descriptors are defined using this context.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]350
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]351</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 Criswell5dacd082010-03-17 15:01:50 +0000[diff] [blame]372<p>These descriptors contain information for a file. Global variables and top
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]373 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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]379
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]380</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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]389<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]390<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]391!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 Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]399 metadata, ;; Reference to file where defined
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]400 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 Gohmanecfb95c2010-05-28 17:13:49 +0000[diff] [blame]404 {}* ;; Reference to the global variable
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]405}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]406</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]407</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]408
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]421<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]422<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]423!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 Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]431 metadata, ;; Reference to file where defined
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]432 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 Patelc7f19972010-06-04 22:49:55 +0000[diff] [blame]436 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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]443}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]444</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]445</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]446
447<p>These descriptors provide debug information about functions, methods and
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]448 subprograms. They provide details such as name, return types and the source
449 location where the subprogram is defined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]450
451</div>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]452
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]453<!-- ======================================================================= -->
454<div class="doc_subsubsection">
455 <a name="format_blocks">Block descriptors</a>
456</div>
457
458<div class="doc_text">
459
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]460<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]461<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]462!3 = metadata !{
463 i32, ;; Tag = 13 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
464 metadata ;; Reference to context descriptor
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]465}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]466</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]467</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]468
469<p>These descriptors provide debug information about nested blocks within a
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]470 subprogram. The array of member descriptors is used to define local
471 variables and deeper nested blocks.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]472
473</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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]482<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]483<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]484!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 Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]489 metadata, ;; Reference to file where defined (may be NULL)
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]490 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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]496}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]497</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]498</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]499
500<p>These descriptors define primitive types used in the code. Example int, bool
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]501 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]509
510<p>The type encoding provides the details of the type. The values are typically
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]511 one of the following:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]512
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]513<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]514<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]515DW_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
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]522</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]523</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]524
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]534<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]535<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]536!5 = metadata !{
537 i32, ;; Tag (see below)
538 metadata, ;; Reference to context
539 metadata, ;; Name (may be "" for anonymous types)
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]540 metadata, ;; Reference to file where defined (may be NULL)
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]541 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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]546}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]547</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]548</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]549
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 Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]552tag values:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]553
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]554<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]555<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]556DW_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
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]564</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]565</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]566
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]567<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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]573
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]574<p><tt>DW_TAG_typedef</tt> is used to provide a name for the derived type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]575
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]576<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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]580
581<p><a href="#format_derived_type">Derived type</a> location can be determined
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]582 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]588
589<p>Note that the <tt>void *</tt> type is expressed as a
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]590 <tt>llvm.dbg.derivedtype.type</tt> with tag of <tt>DW_TAG_pointer_type</tt>
591 and <tt>NULL</tt> derived type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]592
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]602<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]603<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]604!6 = metadata !{
605 i32, ;; Tag (see below)
606 metadata, ;; Reference to context
607 metadata, ;; Name (may be "" for anonymous types)
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]608 metadata, ;; Reference to file where defined (may be NULL)
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]609 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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]617}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]618</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]619</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]620
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 Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]623are possible tag values:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]624
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]625<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]626<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]627DW_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 Lopes7ad46092009-05-29 17:08:57 +0000[diff] [blame]632DW_TAG_subroutine_type = 21
633DW_TAG_inheritance = 28
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]634</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]635</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]636
637<p>The vector flag indicates that an array type is a native packed vector.</p>
638
639<p>The members of array types (tag = <tt>DW_TAG_array_type</tt>) or vector types
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]640 (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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]643
644<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]645 <a href="#format_enumeration">enumerator descriptors</a>, each representing
646 the definition of enumeration value for the set.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]647
648<p>The members of structure (tag = <tt>DW_TAG_structure_type</tt>) or union (tag
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]649 = <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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]654
655<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]656 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]666
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]667<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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]670
671<p><a href="#format_composite_type">Composite type</a> location can be
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]672 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]678
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]688<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]689<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]690%<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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]695</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]696</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]697
698<p>These descriptors are used to define ranges of array subscripts for an array
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]699 <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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]703
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]713<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]714<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]715!6 = metadata !{
716 i32, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
717 ;; (DW_TAG_enumerator)
718 metadata, ;; Name
719 i64 ;; Value
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]720}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]721</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]722</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]723
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]724<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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]727
728</div>
729
730<!-- ======================================================================= -->
731<div class="doc_subsubsection">
732 <a name="format_variables">Local variables</a>
733</div>
734
735<div class="doc_text">
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]736
737<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]738<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]739!7 = metadata !{
740 i32, ;; Tag (see below)
741 metadata, ;; Context
742 metadata, ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]743 metadata, ;; Reference to file where defined
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]744 i32, ;; Line number where defined
745 metadata ;; Type descriptor
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]746}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]747</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]748</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]749
750<p>These descriptors are used to define variables local to a sub program. The
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]751 value of the tag depends on the usage of the variable:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]752
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]753<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]754<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]755DW_TAG_auto_variable = 256
756DW_TAG_arg_variable = 257
757DW_TAG_return_variable = 258
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]758</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]759</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]760
761<p>An auto variable is any variable declared in the body of the function. An
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]762 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]765
766<p>The context is either the subprogram or block where the variable is defined.
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]767 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]770
771</div>
772
773<!-- ======================================================================= -->
774<div class="doc_subsection">
775 <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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]781 provide debug information at various points in generated code.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]782
783</div>
784
785<!-- ======================================================================= -->
786<div class="doc_subsubsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]787 <a name="format_common_declare">llvm.dbg.declare</a>
788</div>
789
790<div class="doc_text">
791<pre>
Dan Gohmanecfb95c2010-05-28 17:13:49 +0000[diff] [blame]792 void %<a href="#format_common_declare">llvm.dbg.declare</a>({}*, metadata)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]793</pre>
794
795<p>This intrinsic provides information about a local element (ex. variable.) The
Dan Gohmanecfb95c2010-05-28 17:13:49 +0000[diff] [blame]796 first argument is the alloca for the variable, cast to a <tt>{}*</tt>. The
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]797 second argument is
798 the <tt>%<a href="#format_variables">llvm.dbg.variable</a></tt> containing
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]799 the description of the variable. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]800
801</div>
802
803<!-- ======================================================================= -->
Victor Hernandez128bf422010-01-11 22:53:48 +0000[diff] [blame]804<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 Gohmand1ec0af2010-05-28 17:07:41 +0000[diff] [blame]810 void %<a href="#format_common_value">llvm.dbg.value</a>(metadata, i64, metadata)
Victor Hernandez128bf422010-01-11 22:53:48 +0000[diff] [blame]811</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<!-- ======================================================================= -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]823<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]824 <a name="format_common_lifetime">Object lifetimes and scoping</a>
825</div>
826
827<div class="doc_text">
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]828<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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]830 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 Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]833 concept, it is non-trivial to model in LLVM, because it has no notion of
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]834 scoping in this sense, and does not want to be tied to a language's scoping
835 rules.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]836
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]837<p>In order to handle this, the LLVM debug format uses the metadata attached to
Nick Lewycky30b67f92010-03-31 07:50:17 +0000[diff] [blame]838 llvm instructions to encode line number and scoping information. Consider
839 the following C fragment, for example:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]840
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]841<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]842<pre>
8431. void foo() {
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]8442. int X = 21;
8453. int Y = 22;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8464. {
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]8475. int Z = 23;
8486. Z = X;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8497. }
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]8508. X = Y;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8519. }
852</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]853</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]854
855<p>Compiled to LLVM, this function would be represented like this:</p>
856
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]857<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]858<pre>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]859define void @foo() nounwind ssp {
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]860entry:
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]861 %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 Gohmanecfb95c2010-05-28 17:13:49 +0000[diff] [blame]864 %0 = bitcast i32* %X to {}* ; &lt;{}*&gt; [#uses=1]
865 call void @llvm.dbg.declare({}* %0, metadata !0), !dbg !7
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]866 store i32 21, i32* %X, !dbg !8
Dan Gohmanecfb95c2010-05-28 17:13:49 +0000[diff] [blame]867 %1 = bitcast i32* %Y to {}* ; &lt;{}*&gt; [#uses=1]
868 call void @llvm.dbg.declare({}* %1, metadata !9), !dbg !10
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]869 store i32 22, i32* %Y, !dbg !11
Dan Gohmanecfb95c2010-05-28 17:13:49 +0000[diff] [blame]870 %2 = bitcast i32* %Z to {}* ; &lt;{}*&gt; [#uses=1]
871 call void @llvm.dbg.declare({}* %2, metadata !12), !dbg !14
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]872 store i32 23, i32* %Z, !dbg !15
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]873 %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 Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]876 store i32 %add, i32* %Z, !dbg !16
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]877 %tmp2 = load i32* %Y, !dbg !17 ; &lt;i32&gt; [#uses=1]
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]878 store i32 %tmp2, i32* %X, !dbg !17
879 ret void, !dbg !18
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]880}
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]881
Dan Gohmanecfb95c2010-05-28 17:13:49 +0000[diff] [blame]882declare void @llvm.dbg.declare({}*, metadata) nounwind readnone
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]883
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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]912</pre>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]913</div>
914
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]915<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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]921
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]922<div class="doc_code">
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]923<pre>
Dan Gohmanecfb95c2010-05-28 17:13:49 +0000[diff] [blame]924call void @llvm.dbg.declare({}* %0, metadata !0), !dbg !7
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]925</pre>
926</div>
927
928<p>The first intrinsic
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]929 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]930 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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]933
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]934<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 Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]948 <tt>!1</tt>. <tt>!1</tt> represents a lexical block inside the scope
949 <tt>!2</tt>, where <tt>!2</tt> is a
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]950 <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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]954
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]955<p>Now lets take another example.</p>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]956
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]957<div class="doc_code">
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]958<pre>
Dan Gohmanecfb95c2010-05-28 17:13:49 +0000[diff] [blame]959call void @llvm.dbg.declare({}* %2, metadata !12), !dbg !14
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]960</pre>
961</div>
962
963<p>The second intrinsic
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]964 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]965 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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]968
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]969<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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]975
John Criswell5dacd082010-03-17 15:01:50 +0000[diff] [blame]976<p>Here <tt>!14</tt> indicates that <tt>Z</tt> is declared at line number 5 and
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]977 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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]983</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]984
985<!-- *********************************************************************** -->
986<div class="doc_section">
987 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
988</div>
989<!-- *********************************************************************** -->
990
991<div class="doc_text">
992
993<p>The C and C++ front-ends represent information about the program in a format
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]994 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1000
1001<p>This section describes the forms used to represent C and C++ programs. Other
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1002 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1008
1009<p>The following sections provide examples of various C/C++ constructs and the
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1010 debug information that would best describe those constructs.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1011
1012</div>
1013
1014<!-- ======================================================================= -->
1015<div class="doc_subsection">
1016 <a name="ccxx_compile_units">C/C++ source file information</a>
1017</div>
1018
1019<div class="doc_text">
1020
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1021<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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1023
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1024<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1025<pre>
1026#include "MyHeader.h"
1027
1028int main(int argc, char *argv[]) {
1029 return 0;
1030}
1031</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1032</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1033
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1034<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1035
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1036<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1037<pre>
1038...
1039;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1040;; Define the compile unit for the main source file "/Users/mine/sources/MySource.cpp".
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1041;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1042!2 = metadata !{
1043 i32 524305, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1044 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
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1054;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1055;; Define the file for the file "/Users/mine/sources/MySource.cpp".
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1056;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1057!1 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1058 i32 524329, ;; Tag
1059 metadata !"MySource.cpp",
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1060 metadata !"/Users/mine/sources",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1061 metadata !3 ;; Compile unit
1062}
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",
1071 metadata !3 ;; Compile unit
1072}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1073
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1074...
1075</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1076</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1077
Devang Patel2c38c572010-03-26 19:08:36 +0000[diff] [blame]1078<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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1090</div>
1091
1092<!-- ======================================================================= -->
1093<div class="doc_subsection">
1094 <a name="ccxx_global_variable">C/C++ global variable information</a>
1095</div>
1096
1097<div class="doc_text">
1098
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1099<p>Given an integer global variable declared as follows:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1100
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1101<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1102<pre>
1103int MyGlobal = 100;
1104</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1105</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1106
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1107<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1108
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1109<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1110<pre>
1111;;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1112;; Define the global itself.
1113;;
1114%MyGlobal = global int 100
1115...
1116;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1117;; List of debug info of globals
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1118;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1119!llvm.dbg.gv = !{!0}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1120
1121;;
1122;; Define the global variable descriptor. Note the reference to the global
1123;; variable anchor and the global variable itself.
1124;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1125!0 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1126 i32 524340, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1127 i32 0, ;; Unused
1128 metadata !1, ;; Context
1129 metadata !"MyGlobal", ;; Name
1130 metadata !"MyGlobal", ;; Display Name
1131 metadata !"MyGlobal", ;; Linkage Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1132 metadata !3, ;; Compile Unit
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1133 i32 1, ;; Line Number
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1134 metadata !4, ;; Type
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1135 i1 false, ;; Is a local variable
1136 i1 true, ;; Is this a definition
1137 i32* @MyGlobal ;; The global variable
1138}
1139
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1140;;
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 Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1144!4 = metadata !{
1145 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1146 metadata !1, ;; Context
1147 metadata !"int", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1148 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1149 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1156
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1157</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1158</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1159
1160</div>
1161
1162<!-- ======================================================================= -->
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 Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1169<p>Given a function declared as follows:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1170
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1171<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1172<pre>
1173int main(int argc, char *argv[]) {
1174 return 0;
1175}
1176</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1177</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1178
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1179<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1180
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1181<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1182<pre>
1183;;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1184;; 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 Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1188!6 = metadata !{
1189 i32 524334, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1190 i32 0, ;; Unused
1191 metadata !1, ;; Context
1192 metadata !"main", ;; Name
1193 metadata !"main", ;; Display name
1194 metadata !"main", ;; Linkage name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1195 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1196 i32 1, ;; Line number
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1197 metadata !4, ;; Type
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1198 i1 false, ;; Is local
1199 i1 true ;; Is definition
1200}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1201;;
1202;; Define the subprogram itself.
1203;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1204define i32 @main(i32 %argc, i8** %argv) {
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1205...
1206}
1207</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1208</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1209
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 Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1219<p>The following are the basic type descriptors for C/C++ core types:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1220
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1230<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1231<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1232!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1233 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1234 metadata !1, ;; Context
1235 metadata !"bool", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1236 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1237 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1244</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1245</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1246
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1256<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1257<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1258!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1259 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1260 metadata !1, ;; Context
1261 metadata !"char", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1262 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1263 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1270</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1271</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1272
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1282<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1283<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1284!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1285 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1286 metadata !1, ;; Context
1287 metadata !"unsigned char",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1288 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1289 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1296</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1297</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1298
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1308<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1309<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1310!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1311 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1312 metadata !1, ;; Context
1313 metadata !"short int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1314 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1315 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1322</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1323</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1324
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1334<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1335<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1336!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1337 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1338 metadata !1, ;; Context
1339 metadata !"short unsigned int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1340 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1341 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1348</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1349</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1350
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1360<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1361<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1362!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1363 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1364 metadata !1, ;; Context
1365 metadata !"int", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1366 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1367 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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1374</pre></div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1375
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1385<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1386<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1387!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1388 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1389 metadata !1, ;; Context
1390 metadata !"unsigned int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1391 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1392 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1399</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1400</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1401
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1411<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1412<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1413!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1414 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1415 metadata !1, ;; Context
1416 metadata !"long long int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1417 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1418 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1425</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1426</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1427
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1437<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1438<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1439!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1440 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1441 metadata !1, ;; Context
1442 metadata !"long long unsigned int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1443 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1444 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1451</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1452</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1453
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1463<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1464<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1465!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1466 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1467 metadata !1, ;; Context
1468 metadata !"float",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1469 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1470 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1477</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1478</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1479
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 Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1489<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1490<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1491!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1492 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1493 metadata !1, ;; Context
1494 metadata !"double",;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1495 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1496 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1503</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1504</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1505
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 Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1515<p>Given the following as an example of C/C++ derived type:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1516
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1517<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1518<pre>
1519typedef const int *IntPtr;
1520</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1521</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1522
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1523<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1524
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1525<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1526<pre>
1527;;
1528;; Define the typedef "IntPtr".
1529;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1530!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1531 i32 524310, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1532 metadata !1, ;; Context
1533 metadata !"IntPtr", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1534 metadata !3, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1535 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1542
1543;;
1544;; Define the pointer type.
1545;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1546!4 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1547 i32 524303, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1548 metadata !1, ;; Context
1549 metadata !"", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1550 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1551 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1558;;
1559;; Define the const type.
1560;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1561!5 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1562 i32 524326, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1563 metadata !1, ;; Context
1564 metadata !"", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1565 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1566 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1573;;
1574;; Define the int type.
1575;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1576!6 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1577 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1578 metadata !1, ;; Context
1579 metadata !"int", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1580 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1581 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1588</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1589</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1590
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 Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1600<p>Given the following as an example of C/C++ struct type:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1601
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1602<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1603<pre>
1604struct Color {
1605 unsigned Red;
1606 unsigned Green;
1607 unsigned Blue;
1608};
1609</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1610</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1611
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1612<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1613
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1614<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1615<pre>
1616;;
1617;; Define basic type for unsigned int.
1618;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1619!5 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1620 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1621 metadata !1, ;; Context
1622 metadata !"unsigned int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1623 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1624 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1631;;
1632;; Define composite type for struct Color.
1633;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1634!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1635 i32 524307, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1636 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1648
1649;;
1650;; Define the Red field.
1651;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1652!4 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1653 i32 524301, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1654 metadata !1, ;; Context
1655 metadata !"Red", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1656 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1657 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1664
1665;;
1666;; Define the Green field.
1667;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1668!6 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1669 i32 524301, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1670 metadata !1, ;; Context
1671 metadata !"Green", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1672 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1673 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1680
1681;;
1682;; Define the Blue field.
1683;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1684!7 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1685 i32 524301, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1686 metadata !1, ;; Context
1687 metadata !"Blue", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1688 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1689 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}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1696
1697;;
1698;; Define the array of fields used by the composite type Color.
1699;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1700!3 = metadata !{metadata !4, metadata !6, metadata !7}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1701</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1702</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1703
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 Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1713<p>Given the following as an example of C/C++ enumeration type:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1714
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1715<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1716<pre>
1717enum Trees {
1718 Spruce = 100,
1719 Oak = 200,
1720 Maple = 300
1721};
1722</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1723</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1724
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1725<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1726
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1727<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1728<pre>
1729;;
1730;; Define composite type for enum Trees
1731;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1732!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1733 i32 524292, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1734 metadata !1, ;; Context
1735 metadata !"Trees", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1736 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1737 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 Patel57b83c72009-08-25 05:24:07 +0000[diff] [blame]1746
Devang Patel94060422009-08-26 05:01:18 +0000[diff] [blame]1747;;
1748;; Define the array of enumerators used by composite type Trees.
1749;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1750!3 = metadata !{metadata !4, metadata !5, metadata !6}
1751
1752;;
1753;; Define Spruce enumerator.
1754;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1755!4 = metadata !{i32 524328, metadata !"Spruce", i64 100}
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1756
1757;;
1758;; Define Oak enumerator.
1759;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1760!5 = metadata !{i32 524328, metadata !"Oak", i64 200}
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1761
1762;;
1763;; Define Maple enumerator.
1764;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1765!6 = metadata !{i32 524328, metadata !"Maple", i64 300}
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1766
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1767</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1768</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1769
1770</div>
1771
1772<!-- *********************************************************************** -->
1773
1774<hr>
1775<address>
1776 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman947321d2008-12-11 17:34:48 +0000[diff] [blame]1777 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1778 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman947321d2008-12-11 17:34:48 +0000[diff] [blame]1779 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1780
1781 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1782 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
1783 Last modified: $Date$
1784</address>
1785
1786</body>
1787</html>