Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 2c38c57931cf36d6af11e1d48ae8db4ea75deb31 / . / docs / SourceLevelDebugging.html
blob: f92a1656a901433a48825a62580ee77792e65103 [file] [log] [blame]
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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
147<p>Currently, debug information is consumed by the DwarfWriter 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
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]292 are restricted to only the simple data types <tt>int</tt>, <tt>uint</tt>,
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]293 <tt>bool</tt>, <tt>float</tt>, <tt>double</tt>, <tt>mdstring</tt> and
294 <tt>mdnode</tt>. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]295
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]296<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]297<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]298!1 = metadata !{
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]299 uint, ;; A tag
300 ...
301}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]302</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]303</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]304
305<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]306 <tt>uint</tt> containing a tag value identifying the content of the
307 descriptor. The remaining fields are specific to the descriptor. The values
308 of tags are loosely bound to the tag values of DWARF information entries.
309 However, that does not restrict the use of the information supplied to DWARF
310 targets. To facilitate versioning of debug information, the tag is augmented
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]311 with the current debug version (LLVMDebugVersion = 8 << 16 or 0x80000 or
312 524288.)</a></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]313
314<p>The details of the various descriptors follow.</p>
315
316</div>
317
318<!-- ======================================================================= -->
319<div class="doc_subsubsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]320 <a name="format_compile_units">Compile unit descriptors</a>
321</div>
322
323<div class="doc_text">
324
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]325<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]326<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]327!0 = metadata !{
328 i32, ;; Tag = 17 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
329 ;; (DW_TAG_compile_unit)
330 i32, ;; Unused field.
331 i32, ;; DWARF language identifier (ex. DW_LANG_C89)
332 metadata, ;; Source file name
333 metadata, ;; Source file directory (includes trailing slash)
334 metadata ;; Producer (ex. "4.0.1 LLVM (LLVM research group)")
335 i1, ;; True if this is a main compile unit.
336 i1, ;; True if this is optimized.
337 metadata, ;; Flags
338 i32 ;; Runtime version
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]339}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]340</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]341</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]342
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]343<p>These descriptors contain a source language ID for the file (we use the DWARF
344 3.0 ID numbers, such as <tt>DW_LANG_C89</tt>, <tt>DW_LANG_C_plus_plus</tt>,
345 <tt>DW_LANG_Cobol74</tt>, etc), three strings describing the filename,
346 working directory of the compiler, and an identifier string for the compiler
347 that produced it.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]348
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]349<p>Compile unit descriptors provide the root context for objects declared in a
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]350 specific compilation unit. File descriptors are defined using this context.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]351
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]352</div>
353
354<!-- ======================================================================= -->
355<div class="doc_subsubsection">
356 <a name="format_files">File descriptors</a>
357</div>
358
359<div class="doc_text">
360
361<div class="doc_code">
362<pre>
363!0 = metadata !{
364 i32, ;; Tag = 41 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
365 ;; (DW_TAG_file_type)
366 metadata, ;; Source file name
367 metadata, ;; Source file directory (includes trailing slash)
368 metadata ;; Reference to compile unit where defined
369}
370</pre>
371</div>
372
John Criswell5dacd082010-03-17 15:01:50 +0000[diff] [blame]373<p>These descriptors contain information for a file. Global variables and top
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]374 level functions would be defined using this context.k File descriptors also
375 provide context for source line correspondence. </p>
376
377<p>Each input file is encoded as a separate file descriptor in LLVM debugging
378 information output. Each file descriptor would be defined using a
379 compile unit. </p>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]380
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]381</div>
382
383<!-- ======================================================================= -->
384<div class="doc_subsubsection">
385 <a name="format_global_variables">Global variable descriptors</a>
386</div>
387
388<div class="doc_text">
389
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]390<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]391<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]392!1 = metadata !{
393 i32, ;; Tag = 52 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
394 ;; (DW_TAG_variable)
395 i32, ;; Unused field.
396 metadata, ;; Reference to context descriptor
397 metadata, ;; Name
398 metadata, ;; Display name (fully qualified C++ name)
399 metadata, ;; MIPS linkage name (for C++)
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]400 metadata, ;; Reference to file where defined
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]401 i32, ;; Line number where defined
402 metadata, ;; Reference to type descriptor
403 i1, ;; True if the global is local to compile unit (static)
404 i1, ;; True if the global is defined in the compile unit (not extern)
405 { }* ;; Reference to the global variable
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]406}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]407</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]408</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]409
410<p>These descriptors provide debug information about globals variables. The
411provide details such as name, type and where the variable is defined.</p>
412
413</div>
414
415<!-- ======================================================================= -->
416<div class="doc_subsubsection">
417 <a name="format_subprograms">Subprogram descriptors</a>
418</div>
419
420<div class="doc_text">
421
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]422<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]423<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]424!2 = metadata !{
425 i32, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
426 ;; (DW_TAG_subprogram)
427 i32, ;; Unused field.
428 metadata, ;; Reference to context descriptor
429 metadata, ;; Name
430 metadata, ;; Display name (fully qualified C++ name)
431 metadata, ;; MIPS linkage name (for C++)
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]432 metadata, ;; Reference to file where defined
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]433 i32, ;; Line number where defined
434 metadata, ;; Reference to type descriptor
435 i1, ;; True if the global is local to compile unit (static)
436 i1 ;; True if the global is defined in the compile unit (not extern)
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]437}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]438</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]439</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]440
441<p>These descriptors provide debug information about functions, methods and
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]442 subprograms. They provide details such as name, return types and the source
443 location where the subprogram is defined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]444
445</div>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]446
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]447<!-- ======================================================================= -->
448<div class="doc_subsubsection">
449 <a name="format_blocks">Block descriptors</a>
450</div>
451
452<div class="doc_text">
453
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]454<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]455<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]456!3 = metadata !{
457 i32, ;; Tag = 13 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
458 metadata ;; Reference to context descriptor
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]459}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]460</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]461</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]462
463<p>These descriptors provide debug information about nested blocks within a
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]464 subprogram. The array of member descriptors is used to define local
465 variables and deeper nested blocks.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]466
467</div>
468
469<!-- ======================================================================= -->
470<div class="doc_subsubsection">
471 <a name="format_basic_type">Basic type descriptors</a>
472</div>
473
474<div class="doc_text">
475
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]476<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]477<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]478!4 = metadata !{
479 i32, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
480 ;; (DW_TAG_base_type)
481 metadata, ;; Reference to context (typically a compile unit)
482 metadata, ;; Name (may be "" for anonymous types)
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]483 metadata, ;; Reference to file where defined (may be NULL)
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]484 i32, ;; Line number where defined (may be 0)
485 i64, ;; Size in bits
486 i64, ;; Alignment in bits
487 i64, ;; Offset in bits
488 i32, ;; Flags
489 i32 ;; DWARF type encoding
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]490}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]491</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]492</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]493
494<p>These descriptors define primitive types used in the code. Example int, bool
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]495 and float. The context provides the scope of the type, which is usually the
496 top level. Since basic types are not usually user defined the compile unit
497 and line number can be left as NULL and 0. The size, alignment and offset
498 are expressed in bits and can be 64 bit values. The alignment is used to
499 round the offset when embedded in a
500 <a href="#format_composite_type">composite type</a> (example to keep float
501 doubles on 64 bit boundaries.) The offset is the bit offset if embedded in
502 a <a href="#format_composite_type">composite type</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]503
504<p>The type encoding provides the details of the type. The values are typically
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]505 one of the following:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]506
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]507<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]508<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]509DW_ATE_address = 1
510DW_ATE_boolean = 2
511DW_ATE_float = 4
512DW_ATE_signed = 5
513DW_ATE_signed_char = 6
514DW_ATE_unsigned = 7
515DW_ATE_unsigned_char = 8
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]516</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]517</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]518
519</div>
520
521<!-- ======================================================================= -->
522<div class="doc_subsubsection">
523 <a name="format_derived_type">Derived type descriptors</a>
524</div>
525
526<div class="doc_text">
527
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]528<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]529<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]530!5 = metadata !{
531 i32, ;; Tag (see below)
532 metadata, ;; Reference to context
533 metadata, ;; Name (may be "" for anonymous types)
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]534 metadata, ;; Reference to file where defined (may be NULL)
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]535 i32, ;; Line number where defined (may be 0)
536 i32, ;; Size in bits
537 i32, ;; Alignment in bits
538 i32, ;; Offset in bits
539 metadata ;; Reference to type derived from
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]540}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]541</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]542</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]543
544<p>These descriptors are used to define types derived from other types. The
545value of the tag varies depending on the meaning. The following are possible
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]546tag values:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]547
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]548<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]549<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]550DW_TAG_formal_parameter = 5
551DW_TAG_member = 13
552DW_TAG_pointer_type = 15
553DW_TAG_reference_type = 16
554DW_TAG_typedef = 22
555DW_TAG_const_type = 38
556DW_TAG_volatile_type = 53
557DW_TAG_restrict_type = 55
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]558</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]559</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]560
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]561<p><tt>DW_TAG_member</tt> is used to define a member of
562 a <a href="#format_composite_type">composite type</a>
563 or <a href="#format_subprograms">subprogram</a>. The type of the member is
564 the <a href="#format_derived_type">derived
565 type</a>. <tt>DW_TAG_formal_parameter</tt> is used to define a member which
566 is a formal argument of a subprogram.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]567
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]568<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]569
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]570<p><tt>DW_TAG_pointer_type</tt>,<tt>DW_TAG_reference_type</tt>,
571 <tt>DW_TAG_const_type</tt>, <tt>DW_TAG_volatile_type</tt>
572 and <tt>DW_TAG_restrict_type</tt> are used to qualify
573 the <a href="#format_derived_type">derived type</a>. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]574
575<p><a href="#format_derived_type">Derived type</a> location can be determined
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]576 from the compile unit and line number. The size, alignment and offset are
577 expressed in bits and can be 64 bit values. The alignment is used to round
578 the offset when embedded in a <a href="#format_composite_type">composite
579 type</a> (example to keep float doubles on 64 bit boundaries.) The offset is
580 the bit offset if embedded in a <a href="#format_composite_type">composite
581 type</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]582
583<p>Note that the <tt>void *</tt> type is expressed as a
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]584 <tt>llvm.dbg.derivedtype.type</tt> with tag of <tt>DW_TAG_pointer_type</tt>
585 and <tt>NULL</tt> derived type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]586
587</div>
588
589<!-- ======================================================================= -->
590<div class="doc_subsubsection">
591 <a name="format_composite_type">Composite type descriptors</a>
592</div>
593
594<div class="doc_text">
595
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]596<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]597<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]598!6 = metadata !{
599 i32, ;; Tag (see below)
600 metadata, ;; Reference to context
601 metadata, ;; Name (may be "" for anonymous types)
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]602 metadata, ;; Reference to file where defined (may be NULL)
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]603 i32, ;; Line number where defined (may be 0)
604 i64, ;; Size in bits
605 i64, ;; Alignment in bits
606 i64, ;; Offset in bits
607 i32, ;; Flags
608 metadata, ;; Reference to type derived from
609 metadata, ;; Reference to array of member descriptors
610 i32 ;; Runtime languages
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]611}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]612</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]613</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]614
615<p>These descriptors are used to define types that are composed of 0 or more
616elements. The value of the tag varies depending on the meaning. The following
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]617are possible tag values:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]618
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]619<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]620<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]621DW_TAG_array_type = 1
622DW_TAG_enumeration_type = 4
623DW_TAG_structure_type = 19
624DW_TAG_union_type = 23
625DW_TAG_vector_type = 259
Bruno Cardoso Lopes7ad46092009-05-29 17:08:57 +0000[diff] [blame]626DW_TAG_subroutine_type = 21
627DW_TAG_inheritance = 28
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]628</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]629</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]630
631<p>The vector flag indicates that an array type is a native packed vector.</p>
632
633<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]634 (tag = <tt>DW_TAG_vector_type</tt>) are <a href="#format_subrange">subrange
635 descriptors</a>, each representing the range of subscripts at that level of
636 indexing.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]637
638<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]639 <a href="#format_enumeration">enumerator descriptors</a>, each representing
640 the definition of enumeration value for the set.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]641
642<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]643 = <tt>DW_TAG_union_type</tt>) types are any one of
644 the <a href="#format_basic_type">basic</a>,
645 <a href="#format_derived_type">derived</a>
646 or <a href="#format_composite_type">composite</a> type descriptors, each
647 representing a field member of the structure or union.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]648
649<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]650 provide information about base classes, static members and member
651 functions. If a member is a <a href="#format_derived_type">derived type
652 descriptor</a> and has a tag of <tt>DW_TAG_inheritance</tt>, then the type
653 represents a base class. If the member of is
654 a <a href="#format_global_variables">global variable descriptor</a> then it
655 represents a static member. And, if the member is
656 a <a href="#format_subprograms">subprogram descriptor</a> then it represents
657 a member function. For static members and member
658 functions, <tt>getName()</tt> returns the members link or the C++ mangled
659 name. <tt>getDisplayName()</tt> the simplied version of the name.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]660
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]661<p>The first member of subroutine (tag = <tt>DW_TAG_subroutine_type</tt>) type
662 elements is the return type for the subroutine. The remaining elements are
663 the formal arguments to the subroutine.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]664
665<p><a href="#format_composite_type">Composite type</a> location can be
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]666 determined from the compile unit and line number. The size, alignment and
667 offset are expressed in bits and can be 64 bit values. The alignment is used
668 to round the offset when embedded in
669 a <a href="#format_composite_type">composite type</a> (as an example, to keep
670 float doubles on 64 bit boundaries.) The offset is the bit offset if embedded
671 in a <a href="#format_composite_type">composite type</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]672
673</div>
674
675<!-- ======================================================================= -->
676<div class="doc_subsubsection">
677 <a name="format_subrange">Subrange descriptors</a>
678</div>
679
680<div class="doc_text">
681
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]682<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]683<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]684%<a href="#format_subrange">llvm.dbg.subrange.type</a> = type {
685 i32, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
686 i64, ;; Low value
687 i64 ;; High value
688}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]689</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]690</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]691
692<p>These descriptors are used to define ranges of array subscripts for an array
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]693 <a href="#format_composite_type">composite type</a>. The low value defines
694 the lower bounds typically zero for C/C++. The high value is the upper
695 bounds. Values are 64 bit. High - low + 1 is the size of the array. If low
696 == high the array will be unbounded.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]697
698</div>
699
700<!-- ======================================================================= -->
701<div class="doc_subsubsection">
702 <a name="format_enumeration">Enumerator descriptors</a>
703</div>
704
705<div class="doc_text">
706
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]707<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]708<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]709!6 = metadata !{
710 i32, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
711 ;; (DW_TAG_enumerator)
712 metadata, ;; Name
713 i64 ;; Value
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]714}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]715</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]716</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]717
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]718<p>These descriptors are used to define members of an
719 enumeration <a href="#format_composite_type">composite type</a>, it
720 associates the name to the value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]721
722</div>
723
724<!-- ======================================================================= -->
725<div class="doc_subsubsection">
726 <a name="format_variables">Local variables</a>
727</div>
728
729<div class="doc_text">
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]730
731<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]732<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]733!7 = metadata !{
734 i32, ;; Tag (see below)
735 metadata, ;; Context
736 metadata, ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]737 metadata, ;; Reference to file where defined
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]738 i32, ;; Line number where defined
739 metadata ;; Type descriptor
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]740}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]741</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]742</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]743
744<p>These descriptors are used to define variables local to a sub program. The
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]745 value of the tag depends on the usage of the variable:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]746
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]747<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]748<pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]749DW_TAG_auto_variable = 256
750DW_TAG_arg_variable = 257
751DW_TAG_return_variable = 258
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]752</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]753</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]754
755<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]756 argument variable is any variable that appears as a formal argument to the
757 function. A return variable is used to track the result of a function and
758 has no source correspondent.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]759
760<p>The context is either the subprogram or block where the variable is defined.
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]761 Name the source variable name. Compile unit and line indicate where the
762 variable was defined. Type descriptor defines the declared type of the
763 variable.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]764
765</div>
766
767<!-- ======================================================================= -->
768<div class="doc_subsection">
769 <a name="format_common_intrinsics">Debugger intrinsic functions</a>
770</div>
771
772<div class="doc_text">
773
774<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]775 provide debug information at various points in generated code.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]776
777</div>
778
779<!-- ======================================================================= -->
780<div class="doc_subsubsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]781 <a name="format_common_declare">llvm.dbg.declare</a>
782</div>
783
784<div class="doc_text">
785<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]786 void %<a href="#format_common_declare">llvm.dbg.declare</a>( { } *, metadata )
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]787</pre>
788
789<p>This intrinsic provides information about a local element (ex. variable.) The
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]790 first argument is the alloca for the variable, cast to a <tt>{ }*</tt>. The
791 second argument is
792 the <tt>%<a href="#format_variables">llvm.dbg.variable</a></tt> containing
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]793 the description of the variable. </p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]794
795</div>
796
797<!-- ======================================================================= -->
Victor Hernandez128bf422010-01-11 22:53:48 +0000[diff] [blame]798<div class="doc_subsubsection">
799 <a name="format_common_value">llvm.dbg.value</a>
800</div>
801
802<div class="doc_text">
803<pre>
804 void %<a href="#format_common_value">llvm.dbg.value</a>( metadata, i64, metadata )
805</pre>
806
807<p>This intrinsic provides information when a user source variable is set to a
808 new value. The first argument is the new value (wrapped as metadata). The
809 second argument is the offset in the user source variable where the new value
810 is written. The third argument is
811 the <tt>%<a href="#format_variables">llvm.dbg.variable</a></tt> containing
812 the description of the user source variable. </p>
813
814</div>
815
816<!-- ======================================================================= -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]817<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]818 <a name="format_common_lifetime">Object lifetimes and scoping</a>
819</div>
820
821<div class="doc_text">
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]822<p>In many languages, the local variables in functions can have their lifetimes
823 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]824 for example, variables are only live (readable and writable) within the
825 source block that they are defined in. In functional languages, values are
826 only readable after they have been defined. Though this is a very obvious
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]827 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]828 scoping in this sense, and does not want to be tied to a language's scoping
829 rules.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]830
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]831<p>In order to handle this, the LLVM debug format uses the metadata attached to
832 llvm instructions to encode line nuber and scoping information. Consider the
833 following C fragment, for example:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]834
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]835<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]836<pre>
8371. void foo() {
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]8382. int X = 21;
8393. int Y = 22;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8404. {
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]8415. int Z = 23;
8426. Z = X;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8437. }
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]8448. X = Y;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8459. }
846</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]847</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]848
849<p>Compiled to LLVM, this function would be represented like this:</p>
850
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]851<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]852<pre>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]853define void @foo() nounwind ssp {
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]854entry:
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]855 %X = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
856 %Y = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
857 %Z = alloca i32, align 4 ; &lt;i32*&gt; [#uses=3]
858 %0 = bitcast i32* %X to { }* ; &lt;{ }*&gt; [#uses=1]
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]859 call void @llvm.dbg.declare({ }* %0, metadata !0), !dbg !7
860 store i32 21, i32* %X, !dbg !8
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]861 %1 = bitcast i32* %Y to { }* ; &lt;{ }*&gt; [#uses=1]
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]862 call void @llvm.dbg.declare({ }* %1, metadata !9), !dbg !10
863 store i32 22, i32* %Y, !dbg !11
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]864 %2 = bitcast i32* %Z to { }* ; &lt;{ }*&gt; [#uses=1]
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]865 call void @llvm.dbg.declare({ }* %2, metadata !12), !dbg !14
866 store i32 23, i32* %Z, !dbg !15
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]867 %tmp = load i32* %X, !dbg !16 ; &lt;i32&gt; [#uses=1]
868 %tmp1 = load i32* %Y, !dbg !16 ; &lt;i32&gt; [#uses=1]
869 %add = add nsw i32 %tmp, %tmp1, !dbg !16 ; &lt;i32&gt; [#uses=1]
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]870 store i32 %add, i32* %Z, !dbg !16
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]871 %tmp2 = load i32* %Y, !dbg !17 ; &lt;i32&gt; [#uses=1]
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]872 store i32 %tmp2, i32* %X, !dbg !17
873 ret void, !dbg !18
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]874}
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]875
876declare void @llvm.dbg.declare({ }*, metadata) nounwind readnone
877
878!0 = metadata !{i32 459008, metadata !1, metadata !"X",
879 metadata !3, i32 2, metadata !6}; [ DW_TAG_auto_variable ]
880!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
881!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo", metadata !"foo",
882 metadata !"foo", metadata !3, i32 1, metadata !4,
883 i1 false, i1 true}; [DW_TAG_subprogram ]
884!3 = metadata !{i32 458769, i32 0, i32 12, metadata !"foo.c",
885 metadata !"/private/tmp", metadata !"clang 1.1", i1 true,
886 i1 false, metadata !"", i32 0}; [DW_TAG_compile_unit ]
887!4 = metadata !{i32 458773, metadata !3, metadata !"", null, i32 0, i64 0, i64 0,
888 i64 0, i32 0, null, metadata !5, i32 0}; [DW_TAG_subroutine_type ]
889!5 = metadata !{null}
890!6 = metadata !{i32 458788, metadata !3, metadata !"int", metadata !3, i32 0,
891 i64 32, i64 32, i64 0, i32 0, i32 5}; [DW_TAG_base_type ]
892!7 = metadata !{i32 2, i32 7, metadata !1, null}
893!8 = metadata !{i32 2, i32 3, metadata !1, null}
894!9 = metadata !{i32 459008, metadata !1, metadata !"Y", metadata !3, i32 3,
895 metadata !6}; [ DW_TAG_auto_variable ]
896!10 = metadata !{i32 3, i32 7, metadata !1, null}
897!11 = metadata !{i32 3, i32 3, metadata !1, null}
898!12 = metadata !{i32 459008, metadata !13, metadata !"Z", metadata !3, i32 5,
899 metadata !6}; [ DW_TAG_auto_variable ]
900!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
901!14 = metadata !{i32 5, i32 9, metadata !13, null}
902!15 = metadata !{i32 5, i32 5, metadata !13, null}
903!16 = metadata !{i32 6, i32 5, metadata !13, null}
904!17 = metadata !{i32 8, i32 3, metadata !1, null}
905!18 = metadata !{i32 9, i32 1, metadata !2, null}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]906</pre>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]907</div>
908
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]909<p>This example illustrates a few important details about LLVM debugging
910 information. In particular, it shows how the <tt>llvm.dbg.declare</tt>
911 intrinsic and location information, which are attached to an instruction,
912 are applied together to allow a debugger to analyze the relationship between
913 statements, variable definitions, and the code used to implement the
914 function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]915
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]916<div class="doc_code">
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]917<pre>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]918call void @llvm.dbg.declare({ }* %0, metadata !0), !dbg !7
919</pre>
920</div>
921
922<p>The first intrinsic
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]923 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]924 encodes debugging information for the variable <tt>X</tt>. The metadata
925 <tt>!dbg !7</tt> attached to the intrinsic provides scope information for the
926 variable <tt>X</tt>.</p>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]927
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]928<div class="doc_code">
929<pre>
930!7 = metadata !{i32 2, i32 7, metadata !1, null}
931!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
932!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo",
933 metadata !"foo", metadata !"foo", metadata !3, i32 1,
934 metadata !4, i1 false, i1 true}; [DW_TAG_subprogram ]
935</pre>
936</div>
937
938<p>Here <tt>!7</tt> is metadata providing location information. It has four
939 fields: line number, column number, scope, and original scope. The original
940 scope represents inline location if this instruction is inlined inside a
941 caller, and is null otherwise. In this example, scope is encoded by
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]942 <tt>!1</tt>. <tt>!1</tt> represents a lexical block inside the scope
943 <tt>!2</tt>, where <tt>!2</tt> is a
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]944 <a href="#format_subprograms">subprogram descriptor</a>. This way the
945 location information attached to the intrinsics indicates that the
946 variable <tt>X</tt> is declared at line number 2 at a function level scope in
947 function <tt>foo</tt>.</p>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]948
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]949<p>Now lets take another example.</p>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]950
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]951<div class="doc_code">
Bill Wendling05837cd2009-12-01 00:59:58 +0000[diff] [blame]952<pre>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]953call void @llvm.dbg.declare({ }* %2, metadata !12), !dbg !14
954</pre>
955</div>
956
957<p>The second intrinsic
Devang Patelcacef072009-11-25 23:28:01 +0000[diff] [blame]958 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]959 encodes debugging information for variable <tt>Z</tt>. The metadata
960 <tt>!dbg !14</tt> attached to the intrinsic provides scope information for
961 the variable <tt>Z</tt>.</p>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]962
Bill Wendlingd90060e2009-12-01 00:53:11 +0000[diff] [blame]963<div class="doc_code">
964<pre>
965!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
966!14 = metadata !{i32 5, i32 9, metadata !13, null}
967</pre>
968</div>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]969
John Criswell5dacd082010-03-17 15:01:50 +0000[diff] [blame]970<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]971 column number 9 inside of lexical scope <tt>!13</tt>. The lexical scope
972 itself resides inside of lexical scope <tt>!1</tt> described above.</p>
973
974<p>The scope information attached with each instruction provides a
975 straightforward way to find instructions covered by a scope.</p>
976
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]977</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]978
979<!-- *********************************************************************** -->
980<div class="doc_section">
981 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
982</div>
983<!-- *********************************************************************** -->
984
985<div class="doc_text">
986
987<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]988 that is effectively identical
989 to <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3.0</a> in
990 terms of information content. This allows code generators to trivially
991 support native debuggers by generating standard dwarf information, and
992 contains enough information for non-dwarf targets to translate it as
993 needed.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]994
995<p>This section describes the forms used to represent C and C++ programs. Other
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]996 languages could pattern themselves after this (which itself is tuned to
997 representing programs in the same way that DWARF 3 does), or they could
998 choose to provide completely different forms if they don't fit into the DWARF
999 model. As support for debugging information gets added to the various LLVM
1000 source-language front-ends, the information used should be documented
1001 here.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1002
1003<p>The following sections provide examples of various C/C++ constructs and the
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1004 debug information that would best describe those constructs.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1005
1006</div>
1007
1008<!-- ======================================================================= -->
1009<div class="doc_subsection">
1010 <a name="ccxx_compile_units">C/C++ source file information</a>
1011</div>
1012
1013<div class="doc_text">
1014
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1015<p>Given the source files <tt>MySource.cpp</tt> and <tt>MyHeader.h</tt> located
1016 in the directory <tt>/Users/mine/sources</tt>, the following code:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1017
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1018<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1019<pre>
1020#include "MyHeader.h"
1021
1022int main(int argc, char *argv[]) {
1023 return 0;
1024}
1025</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1026</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1027
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1028<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1029
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1030<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1031<pre>
1032...
1033;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1034;; Define the compile unit for the main source file "/Users/mine/sources/MySource.cpp".
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1035;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1036!2 = metadata !{
1037 i32 524305, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1038 i32 0, ;; Unused
1039 i32 4, ;; Language Id
1040 metadata !"MySource.cpp",
1041 metadata !"/Users/mine/sources",
1042 metadata !"4.2.1 (Based on Apple Inc. build 5649) (LLVM build 00)",
1043 i1 true, ;; Main Compile Unit
1044 i1 false, ;; Optimized compile unit
1045 metadata !"", ;; Compiler flags
1046 i32 0} ;; Runtime version
1047
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1048;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1049;; Define the file for the file "/Users/mine/sources/MySource.cpp".
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1050;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1051!1 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1052 i32 524329, ;; Tag
1053 metadata !"MySource.cpp",
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1054 metadata !"/Users/mine/sources",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1055 metadata !3 ;; Compile unit
1056}
1057
1058;;
1059;; Define the file for the file "/Users/mine/sources/Myheader.h"
1060;;
1061!3 = metadata !{
1062 i32 524329, ;; Tag
1063 metadata !"Myheader.h"
1064 metadata !"/Users/mine/sources",
1065 metadata !3 ;; Compile unit
1066}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1067
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1068...
1069</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1070</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1071
Devang Patel2c38c572010-03-26 19:08:36 +0000[diff] [blame^]1072<p>llvm::Instruction provides easy access to metadata attached with an
1073instruction. One can extract line number information encoded in LLVM IR
1074using <tt>Instruction::getMetadata()</tt> and
1075<tt>DILocation::getLineNumber()</tt>.
1076<pre>
1077 if (MDNode *N = I->getMetadata("dbg")) { // Here I is an LLVM instruction
1078 DILocation Loc(N); // DILocation is in DebugInfo.h
1079 unsigned Line = Loc.getLineNumber();
1080 StringRef File = Loc.getFilename();
1081 StringRef Dir = Loc.getDirectory();
1082 }
1083</pre>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1084</div>
1085
1086<!-- ======================================================================= -->
1087<div class="doc_subsection">
1088 <a name="ccxx_global_variable">C/C++ global variable information</a>
1089</div>
1090
1091<div class="doc_text">
1092
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1093<p>Given an integer global variable declared as follows:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1094
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1095<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1096<pre>
1097int MyGlobal = 100;
1098</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1099</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1100
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1101<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1102
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1103<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1104<pre>
1105;;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1106;; Define the global itself.
1107;;
1108%MyGlobal = global int 100
1109...
1110;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1111;; List of debug info of globals
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1112;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1113!llvm.dbg.gv = !{!0}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1114
1115;;
1116;; Define the global variable descriptor. Note the reference to the global
1117;; variable anchor and the global variable itself.
1118;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1119!0 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1120 i32 524340, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1121 i32 0, ;; Unused
1122 metadata !1, ;; Context
1123 metadata !"MyGlobal", ;; Name
1124 metadata !"MyGlobal", ;; Display Name
1125 metadata !"MyGlobal", ;; Linkage Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1126 metadata !3, ;; Compile Unit
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1127 i32 1, ;; Line Number
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1128 metadata !4, ;; Type
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1129 i1 false, ;; Is a local variable
1130 i1 true, ;; Is this a definition
1131 i32* @MyGlobal ;; The global variable
1132}
1133
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1134;;
1135;; Define the basic type of 32 bit signed integer. Note that since int is an
1136;; intrinsic type the source file is NULL and line 0.
1137;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1138!4 = metadata !{
1139 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1140 metadata !1, ;; Context
1141 metadata !"int", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1142 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1143 i32 0, ;; Line number
1144 i64 32, ;; Size in Bits
1145 i64 32, ;; Align in Bits
1146 i64 0, ;; Offset in Bits
1147 i32 0, ;; Flags
1148 i32 5 ;; Encoding
1149}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1150
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1151</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1152</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1153
1154</div>
1155
1156<!-- ======================================================================= -->
1157<div class="doc_subsection">
1158 <a name="ccxx_subprogram">C/C++ function information</a>
1159</div>
1160
1161<div class="doc_text">
1162
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1163<p>Given a function declared as follows:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1164
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1165<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1166<pre>
1167int main(int argc, char *argv[]) {
1168 return 0;
1169}
1170</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1171</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1172
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1173<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1174
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1175<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1176<pre>
1177;;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1178;; Define the anchor for subprograms. Note that the second field of the
1179;; anchor is 46, which is the same as the tag for subprograms
1180;; (46 = DW_TAG_subprogram.)
1181;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1182!6 = metadata !{
1183 i32 524334, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1184 i32 0, ;; Unused
1185 metadata !1, ;; Context
1186 metadata !"main", ;; Name
1187 metadata !"main", ;; Display name
1188 metadata !"main", ;; Linkage name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1189 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1190 i32 1, ;; Line number
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1191 metadata !4, ;; Type
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1192 i1 false, ;; Is local
1193 i1 true ;; Is definition
1194}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1195;;
1196;; Define the subprogram itself.
1197;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1198define i32 @main(i32 %argc, i8** %argv) {
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1199...
1200}
1201</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1202</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1203
1204</div>
1205
1206<!-- ======================================================================= -->
1207<div class="doc_subsection">
1208 <a name="ccxx_basic_types">C/C++ basic types</a>
1209</div>
1210
1211<div class="doc_text">
1212
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1213<p>The following are the basic type descriptors for C/C++ core types:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1214
1215</div>
1216
1217<!-- ======================================================================= -->
1218<div class="doc_subsubsection">
1219 <a name="ccxx_basic_type_bool">bool</a>
1220</div>
1221
1222<div class="doc_text">
1223
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1224<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1225<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1226!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1227 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1228 metadata !1, ;; Context
1229 metadata !"bool", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1230 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1231 i32 0, ;; Line number
1232 i64 8, ;; Size in Bits
1233 i64 8, ;; Align in Bits
1234 i64 0, ;; Offset in Bits
1235 i32 0, ;; Flags
1236 i32 2 ;; Encoding
1237}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1238</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1239</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1240
1241</div>
1242
1243<!-- ======================================================================= -->
1244<div class="doc_subsubsection">
1245 <a name="ccxx_basic_char">char</a>
1246</div>
1247
1248<div class="doc_text">
1249
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1250<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1251<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1252!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1253 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1254 metadata !1, ;; Context
1255 metadata !"char", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1256 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1257 i32 0, ;; Line number
1258 i64 8, ;; Size in Bits
1259 i64 8, ;; Align in Bits
1260 i64 0, ;; Offset in Bits
1261 i32 0, ;; Flags
1262 i32 6 ;; Encoding
1263}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1264</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1265</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1266
1267</div>
1268
1269<!-- ======================================================================= -->
1270<div class="doc_subsubsection">
1271 <a name="ccxx_basic_unsigned_char">unsigned char</a>
1272</div>
1273
1274<div class="doc_text">
1275
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1276<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1277<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1278!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1279 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1280 metadata !1, ;; Context
1281 metadata !"unsigned char",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1282 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1283 i32 0, ;; Line number
1284 i64 8, ;; Size in Bits
1285 i64 8, ;; Align in Bits
1286 i64 0, ;; Offset in Bits
1287 i32 0, ;; Flags
1288 i32 8 ;; Encoding
1289}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1290</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1291</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1292
1293</div>
1294
1295<!-- ======================================================================= -->
1296<div class="doc_subsubsection">
1297 <a name="ccxx_basic_short">short</a>
1298</div>
1299
1300<div class="doc_text">
1301
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1302<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1303<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1304!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1305 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1306 metadata !1, ;; Context
1307 metadata !"short int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1308 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1309 i32 0, ;; Line number
1310 i64 16, ;; Size in Bits
1311 i64 16, ;; Align in Bits
1312 i64 0, ;; Offset in Bits
1313 i32 0, ;; Flags
1314 i32 5 ;; Encoding
1315}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1316</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1317</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1318
1319</div>
1320
1321<!-- ======================================================================= -->
1322<div class="doc_subsubsection">
1323 <a name="ccxx_basic_unsigned_short">unsigned short</a>
1324</div>
1325
1326<div class="doc_text">
1327
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1328<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1329<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1330!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1331 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1332 metadata !1, ;; Context
1333 metadata !"short unsigned int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1334 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1335 i32 0, ;; Line number
1336 i64 16, ;; Size in Bits
1337 i64 16, ;; Align in Bits
1338 i64 0, ;; Offset in Bits
1339 i32 0, ;; Flags
1340 i32 7 ;; Encoding
1341}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1342</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1343</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1344
1345</div>
1346
1347<!-- ======================================================================= -->
1348<div class="doc_subsubsection">
1349 <a name="ccxx_basic_int">int</a>
1350</div>
1351
1352<div class="doc_text">
1353
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1354<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1355<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1356!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1357 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1358 metadata !1, ;; Context
1359 metadata !"int", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1360 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1361 i32 0, ;; Line number
1362 i64 32, ;; Size in Bits
1363 i64 32, ;; Align in Bits
1364 i64 0, ;; Offset in Bits
1365 i32 0, ;; Flags
1366 i32 5 ;; Encoding
1367}
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1368</pre></div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1369
1370</div>
1371
1372<!-- ======================================================================= -->
1373<div class="doc_subsubsection">
1374 <a name="ccxx_basic_unsigned_int">unsigned int</a>
1375</div>
1376
1377<div class="doc_text">
1378
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1379<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1380<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1381!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1382 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1383 metadata !1, ;; Context
1384 metadata !"unsigned int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1385 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1386 i32 0, ;; Line number
1387 i64 32, ;; Size in Bits
1388 i64 32, ;; Align in Bits
1389 i64 0, ;; Offset in Bits
1390 i32 0, ;; Flags
1391 i32 7 ;; Encoding
1392}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1393</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1394</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1395
1396</div>
1397
1398<!-- ======================================================================= -->
1399<div class="doc_subsubsection">
1400 <a name="ccxx_basic_long_long">long long</a>
1401</div>
1402
1403<div class="doc_text">
1404
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1405<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1406<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1407!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1408 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1409 metadata !1, ;; Context
1410 metadata !"long long int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1411 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1412 i32 0, ;; Line number
1413 i64 64, ;; Size in Bits
1414 i64 64, ;; Align in Bits
1415 i64 0, ;; Offset in Bits
1416 i32 0, ;; Flags
1417 i32 5 ;; Encoding
1418}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1419</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1420</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1421
1422</div>
1423
1424<!-- ======================================================================= -->
1425<div class="doc_subsubsection">
1426 <a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
1427</div>
1428
1429<div class="doc_text">
1430
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1431<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1432<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1433!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1434 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1435 metadata !1, ;; Context
1436 metadata !"long long unsigned int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1437 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1438 i32 0, ;; Line number
1439 i64 64, ;; Size in Bits
1440 i64 64, ;; Align in Bits
1441 i64 0, ;; Offset in Bits
1442 i32 0, ;; Flags
1443 i32 7 ;; Encoding
1444}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1445</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1446</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1447
1448</div>
1449
1450<!-- ======================================================================= -->
1451<div class="doc_subsubsection">
1452 <a name="ccxx_basic_float">float</a>
1453</div>
1454
1455<div class="doc_text">
1456
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1457<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1458<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1459!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1460 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1461 metadata !1, ;; Context
1462 metadata !"float",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1463 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1464 i32 0, ;; Line number
1465 i64 32, ;; Size in Bits
1466 i64 32, ;; Align in Bits
1467 i64 0, ;; Offset in Bits
1468 i32 0, ;; Flags
1469 i32 4 ;; Encoding
1470}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1471</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1472</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1473
1474</div>
1475
1476<!-- ======================================================================= -->
1477<div class="doc_subsubsection">
1478 <a name="ccxx_basic_double">double</a>
1479</div>
1480
1481<div class="doc_text">
1482
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1483<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1484<pre>
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1485!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1486 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1487 metadata !1, ;; Context
1488 metadata !"double",;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1489 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1490 i32 0, ;; Line number
1491 i64 64, ;; Size in Bits
1492 i64 64, ;; Align in Bits
1493 i64 0, ;; Offset in Bits
1494 i32 0, ;; Flags
1495 i32 4 ;; Encoding
1496}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1497</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1498</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1499
1500</div>
1501
1502<!-- ======================================================================= -->
1503<div class="doc_subsection">
1504 <a name="ccxx_derived_types">C/C++ derived types</a>
1505</div>
1506
1507<div class="doc_text">
1508
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1509<p>Given the following as an example of C/C++ derived type:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1510
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1511<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1512<pre>
1513typedef const int *IntPtr;
1514</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1515</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1516
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1517<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1518
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1519<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1520<pre>
1521;;
1522;; Define the typedef "IntPtr".
1523;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1524!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1525 i32 524310, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1526 metadata !1, ;; Context
1527 metadata !"IntPtr", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1528 metadata !3, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1529 i32 0, ;; Line number
1530 i64 0, ;; Size in bits
1531 i64 0, ;; Align in bits
1532 i64 0, ;; Offset in bits
1533 i32 0, ;; Flags
1534 metadata !4 ;; Derived From type
1535}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1536
1537;;
1538;; Define the pointer type.
1539;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1540!4 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1541 i32 524303, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1542 metadata !1, ;; Context
1543 metadata !"", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1544 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1545 i32 0, ;; Line number
1546 i64 64, ;; Size in bits
1547 i64 64, ;; Align in bits
1548 i64 0, ;; Offset in bits
1549 i32 0, ;; Flags
1550 metadata !5 ;; Derived From type
1551}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1552;;
1553;; Define the const type.
1554;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1555!5 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1556 i32 524326, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1557 metadata !1, ;; Context
1558 metadata !"", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1559 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1560 i32 0, ;; Line number
1561 i64 32, ;; Size in bits
1562 i64 32, ;; Align in bits
1563 i64 0, ;; Offset in bits
1564 i32 0, ;; Flags
1565 metadata !6 ;; Derived From type
1566}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1567;;
1568;; Define the int type.
1569;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1570!6 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1571 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1572 metadata !1, ;; Context
1573 metadata !"int", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1574 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1575 i32 0, ;; Line number
1576 i64 32, ;; Size in bits
1577 i64 32, ;; Align in bits
1578 i64 0, ;; Offset in bits
1579 i32 0, ;; Flags
1580 5 ;; Encoding
1581}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1582</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1583</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1584
1585</div>
1586
1587<!-- ======================================================================= -->
1588<div class="doc_subsection">
1589 <a name="ccxx_composite_types">C/C++ struct/union types</a>
1590</div>
1591
1592<div class="doc_text">
1593
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1594<p>Given the following as an example of C/C++ struct type:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1595
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1596<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1597<pre>
1598struct Color {
1599 unsigned Red;
1600 unsigned Green;
1601 unsigned Blue;
1602};
1603</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1604</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1605
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1606<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1607
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1608<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1609<pre>
1610;;
1611;; Define basic type for unsigned int.
1612;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1613!5 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1614 i32 524324, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1615 metadata !1, ;; Context
1616 metadata !"unsigned int",
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1617 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1618 i32 0, ;; Line number
1619 i64 32, ;; Size in Bits
1620 i64 32, ;; Align in Bits
1621 i64 0, ;; Offset in Bits
1622 i32 0, ;; Flags
1623 i32 7 ;; Encoding
1624}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1625;;
1626;; Define composite type for struct Color.
1627;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1628!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1629 i32 524307, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1630 metadata !1, ;; Context
1631 metadata !"Color", ;; Name
1632 metadata !1, ;; Compile unit
1633 i32 1, ;; Line number
1634 i64 96, ;; Size in bits
1635 i64 32, ;; Align in bits
1636 i64 0, ;; Offset in bits
1637 i32 0, ;; Flags
1638 null, ;; Derived From
1639 metadata !3, ;; Elements
1640 i32 0 ;; Runtime Language
1641}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1642
1643;;
1644;; Define the Red field.
1645;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1646!4 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1647 i32 524301, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1648 metadata !1, ;; Context
1649 metadata !"Red", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1650 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1651 i32 2, ;; Line number
1652 i64 32, ;; Size in bits
1653 i64 32, ;; Align in bits
1654 i64 0, ;; Offset in bits
1655 i32 0, ;; Flags
1656 metadata !5 ;; Derived From type
1657}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1658
1659;;
1660;; Define the Green field.
1661;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1662!6 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1663 i32 524301, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1664 metadata !1, ;; Context
1665 metadata !"Green", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1666 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1667 i32 3, ;; Line number
1668 i64 32, ;; Size in bits
1669 i64 32, ;; Align in bits
1670 i64 32, ;; Offset in bits
1671 i32 0, ;; Flags
1672 metadata !5 ;; Derived From type
1673}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1674
1675;;
1676;; Define the Blue field.
1677;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1678!7 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1679 i32 524301, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1680 metadata !1, ;; Context
1681 metadata !"Blue", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1682 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1683 i32 4, ;; Line number
1684 i64 32, ;; Size in bits
1685 i64 32, ;; Align in bits
1686 i64 64, ;; Offset in bits
1687 i32 0, ;; Flags
1688 metadata !5 ;; Derived From type
1689}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1690
1691;;
1692;; Define the array of fields used by the composite type Color.
1693;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1694!3 = metadata !{metadata !4, metadata !6, metadata !7}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1695</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1696</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1697
1698</div>
1699
1700<!-- ======================================================================= -->
1701<div class="doc_subsection">
1702 <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
1703</div>
1704
1705<div class="doc_text">
1706
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1707<p>Given the following as an example of C/C++ enumeration type:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1708
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1709<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1710<pre>
1711enum Trees {
1712 Spruce = 100,
1713 Oak = 200,
1714 Maple = 300
1715};
1716</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1717</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1718
Misha Brukmane5b22d42008-12-16 02:54:22 +0000[diff] [blame]1719<p>a C/C++ front-end would generate the following descriptors:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1720
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1721<div class="doc_code">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1722<pre>
1723;;
1724;; Define composite type for enum Trees
1725;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1726!2 = metadata !{
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1727 i32 524292, ;; Tag
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1728 metadata !1, ;; Context
1729 metadata !"Trees", ;; Name
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1730 metadata !1, ;; File
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1731 i32 1, ;; Line number
1732 i64 32, ;; Size in bits
1733 i64 32, ;; Align in bits
1734 i64 0, ;; Offset in bits
1735 i32 0, ;; Flags
1736 null, ;; Derived From type
1737 metadata !3, ;; Elements
1738 i32 0 ;; Runtime language
1739}
Devang Patel57b83c72009-08-25 05:24:07 +0000[diff] [blame]1740
Devang Patel94060422009-08-26 05:01:18 +0000[diff] [blame]1741;;
1742;; Define the array of enumerators used by composite type Trees.
1743;;
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1744!3 = metadata !{metadata !4, metadata !5, metadata !6}
1745
1746;;
1747;; Define Spruce enumerator.
1748;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1749!4 = metadata !{i32 524328, metadata !"Spruce", i64 100}
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1750
1751;;
1752;; Define Oak enumerator.
1753;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1754!5 = metadata !{i32 524328, metadata !"Oak", i64 200}
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1755
1756;;
1757;; Define Maple enumerator.
1758;;
Devang Patel1a951462010-03-09 00:44:10 +0000[diff] [blame]1759!6 = metadata !{i32 524328, metadata !"Maple", i64 300}
Devang Patel15e723d2009-08-28 23:24:31 +0000[diff] [blame]1760
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1761</pre>
Bill Wendlingde024832009-05-17 05:52:39 +0000[diff] [blame]1762</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1763
1764</div>
1765
1766<!-- *********************************************************************** -->
1767
1768<hr>
1769<address>
1770 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman947321d2008-12-11 17:34:48 +0000[diff] [blame]1771 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1772 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman947321d2008-12-11 17:34:48 +0000[diff] [blame]1773 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]1774
1775 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1776 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
1777 Last modified: $Date$
1778</address>
1779
1780</body>
1781</html>