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10
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]11<h1>Source Level Debugging with LLVM</h1>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]12
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]13<table class="layout" style="width:100%">
14 <tr class="layout">
15 <td class="left">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]16<ul>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]17 <li><a href="#introduction">Introduction</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]18 <ol>
19 <li><a href="#phil">Philosophy behind LLVM debugging information</a></li>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]20 <li><a href="#consumers">Debug information consumers</a></li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]21 <li><a href="#debugopt">Debugging optimized code</a></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]22 </ol></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]23 <li><a href="#format">Debugging information format</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]24 <ol>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]25 <li><a href="#debug_info_descriptors">Debug information descriptors</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]26 <ul>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]27 <li><a href="#format_compile_units">Compile unit descriptors</a></li>
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]28 <li><a href="#format_files">File descriptors</a></li>
Jim Laskeycec12a52006-03-14 18:08:46 +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>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]31 <li><a href="#format_blocks">Block descriptors</a></li>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]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>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]37 <li><a href="#format_variables">Local variables</a></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]38 </ul></li>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]39 <li><a href="#format_common_intrinsics">Debugger intrinsic functions</a>
40 <ul>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]41 <li><a href="#format_common_declare">llvm.dbg.declare</a></li>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]42 <li><a href="#format_common_value">llvm.dbg.value</a></li>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]43 </ul></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]44 </ol></li>
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]45 <li><a href="#format_common_lifetime">Object lifetimes and scoping</a></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]46 <li><a href="#ccxx_frontend">C/C++ front-end specific debug information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]47 <ol>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]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>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]55 </ol></li>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]56 <li><a href="#llvmdwarfextension">LLVM Dwarf Extensions</a>
57 <ol>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]58 <li><a href="#objcproperty">Debugging Information Extension
Bill Wendling0eb59142012-03-06 09:17:39 +0000[diff] [blame]59 for Objective C Properties</a>
60 <ul>
61 <li><a href="#objcpropertyintroduction">Introduction</a></li>
62 <li><a href="#objcpropertyproposal">Proposal</a></li>
63 <li><a href="#objcpropertynewattributes">New DWARF Attributes</a></li>
64 <li><a href="#objcpropertynewconstants">New DWARF Constants</a></li>
65 </ul>
66 </li>
67 <li><a href="#acceltable">Name Accelerator Tables</a>
68 <ul>
69 <li><a href="#acceltableintroduction">Introduction</a></li>
70 <li><a href="#acceltablehashes">Hash Tables</a></li>
71 <li><a href="#acceltabledetails">Details</a></li>
72 <li><a href="#acceltablecontents">Contents</a></li>
73 <li><a href="#acceltableextensions">Language Extensions and File Format Changes</a></li>
74 </ul>
75 </li>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]76 </ol>
77 </li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]78</ul>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]79</td>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]80<td class="right">
Misha Brukmane849a1a2004-05-12 21:26:16 +0000[diff] [blame]81<img src="img/venusflytrap.jpg" alt="A leafy and green bug eater" width="247"
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]82height="369">
83</td>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]84</tr></table>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]85
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]86<div class="doc_author">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]87 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
Jim Laskeyc760a922007-03-14 19:32:21 +0000[diff] [blame]88 and <a href="mailto:jlaskey@mac.com">Jim Laskey</a></p>
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]89</div>
90
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]91
92<!-- *********************************************************************** -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]93<h2><a name="introduction">Introduction</a></h2>
Misha Brukman94218a72004-12-09 20:27:37 +0000[diff] [blame]94<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]95
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]96<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]97
98<p>This document is the central repository for all information pertaining to
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]99 debug information in LLVM. It describes the <a href="#format">actual format
100 that the LLVM debug information</a> takes, which is useful for those
101 interested in creating front-ends or dealing directly with the information.
Chris Lattner8ad2f982009-07-18 21:47:15 +0000[diff] [blame]102 Further, this document provides specific examples of what debug information
Chris Lattner89940752011-01-18 06:12:10 +0000[diff] [blame]103 for C/C++ looks like.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]104
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]105<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]106<h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]107 <a name="phil">Philosophy behind LLVM debugging information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]108</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]109
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]110<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]111
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]112<p>The idea of the LLVM debugging information is to capture how the important
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]113 pieces of the source-language's Abstract Syntax Tree map onto LLVM code.
114 Several design aspects have shaped the solution that appears here. The
115 important ones are:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]116
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]117<ul>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]118 <li>Debugging information should have very little impact on the rest of the
119 compiler. No transformations, analyses, or code generators should need to
120 be modified because of debugging information.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]121
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]122 <li>LLVM optimizations should interact in <a href="#debugopt">well-defined and
123 easily described ways</a> with the debugging information.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]124
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]125 <li>Because LLVM is designed to support arbitrary programming languages,
126 LLVM-to-LLVM tools should not need to know anything about the semantics of
127 the source-level-language.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]128
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]129 <li>Source-level languages are often <b>widely</b> different from one another.
130 LLVM should not put any restrictions of the flavor of the source-language,
131 and the debugging information should work with any language.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]132
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]133 <li>With code generator support, it should be possible to use an LLVM compiler
134 to compile a program to native machine code and standard debugging
135 formats. This allows compatibility with traditional machine-code level
136 debuggers, like GDB or DBX.</li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]137</ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]138
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]139<p>The approach used by the LLVM implementation is to use a small set
140 of <a href="#format_common_intrinsics">intrinsic functions</a> to define a
141 mapping between LLVM program objects and the source-level objects. The
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]142 description of the source-level program is maintained in LLVM metadata
143 in an <a href="#ccxx_frontend">implementation-defined format</a>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]144 (the C/C++ front-end currently uses working draft 7 of
145 the <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3
146 standard</a>).</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]147
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]148<p>When a program is being debugged, a debugger interacts with the user and
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]149 turns the stored debug information into source-language specific information.
150 As such, a debugger must be aware of the source-language, and is thus tied to
151 a specific language or family of languages.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]152
153</div>
154
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]155<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]156<h3>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]157 <a name="consumers">Debug information consumers</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]158</h3>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]159
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]160<div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]161
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]162<p>The role of debug information is to provide meta information normally
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]163 stripped away during the compilation process. This meta information provides
164 an LLVM user a relationship between generated code and the original program
165 source code.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]166
Chris Lattnerc3107782010-04-05 04:11:11 +0000[diff] [blame]167<p>Currently, debug information is consumed by DwarfDebug to produce dwarf
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]168 information used by the gdb debugger. Other targets could use the same
169 information to produce stabs or other debug forms.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]170
171<p>It would also be reasonable to use debug information to feed profiling tools
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]172 for analysis of generated code, or, tools for reconstructing the original
173 source from generated code.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]174
175<p>TODO - expound a bit more.</p>
176
177</div>
178
179<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]180<h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]181 <a name="debugopt">Debugging optimized code</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]182</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]183
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]184<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]185
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]186<p>An extremely high priority of LLVM debugging information is to make it
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]187 interact well with optimizations and analysis. In particular, the LLVM debug
188 information provides the following guarantees:</p>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]189
190<ul>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]191 <li>LLVM debug information <b>always provides information to accurately read
192 the source-level state of the program</b>, regardless of which LLVM
193 optimizations have been run, and without any modification to the
194 optimizations themselves. However, some optimizations may impact the
195 ability to modify the current state of the program with a debugger, such
196 as setting program variables, or calling functions that have been
197 deleted.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]198
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]199 <li>As desired, LLVM optimizations can be upgraded to be aware of the LLVM
200 debugging information, allowing them to update the debugging information
201 as they perform aggressive optimizations. This means that, with effort,
202 the LLVM optimizers could optimize debug code just as well as non-debug
203 code.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]204
Devang Patele0bdc592011-05-31 17:45:27 +0000[diff] [blame]205 <li>LLVM debug information does not prevent optimizations from
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]206 happening (for example inlining, basic block reordering/merging/cleanup,
Devang Patelf729e912011-05-31 18:06:14 +0000[diff] [blame]207 tail duplication, etc).</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]208
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]209 <li>LLVM debug information is automatically optimized along with the rest of
210 the program, using existing facilities. For example, duplicate
211 information is automatically merged by the linker, and unused information
212 is automatically removed.</li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]213</ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]214
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]215<p>Basically, the debug information allows you to compile a program with
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]216 "<tt>-O0 -g</tt>" and get full debug information, allowing you to arbitrarily
217 modify the program as it executes from a debugger. Compiling a program with
218 "<tt>-O3 -g</tt>" gives you full debug information that is always available
219 and accurate for reading (e.g., you get accurate stack traces despite tail
220 call elimination and inlining), but you might lose the ability to modify the
221 program and call functions where were optimized out of the program, or
222 inlined away completely.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]223
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]224<p><a href="TestingGuide.html#quicktestsuite">LLVM test suite</a> provides a
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]225 framework to test optimizer's handling of debugging information. It can be
226 run like this:</p>
Devang Patela5c05aa2008-11-21 19:35:57 +0000[diff] [blame]227
228<div class="doc_code">
229<pre>
230% cd llvm/projects/test-suite/MultiSource/Benchmarks # or some other level
231% make TEST=dbgopt
232</pre>
233</div>
234
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]235<p>This will test impact of debugging information on optimization passes. If
236 debugging information influences optimization passes then it will be reported
237 as a failure. See <a href="TestingGuide.html">TestingGuide</a> for more
238 information on LLVM test infrastructure and how to run various tests.</p>
Devang Patela5c05aa2008-11-21 19:35:57 +0000[diff] [blame]239
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]240</div>
241
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]242</div>
243
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]244<!-- *********************************************************************** -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]245<h2>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]246 <a name="format">Debugging information format</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]247</h2>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]248<!-- *********************************************************************** -->
249
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]250<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]251
252<p>LLVM debugging information has been carefully designed to make it possible
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]253 for the optimizer to optimize the program and debugging information without
254 necessarily having to know anything about debugging information. In
John Criswellb34500f2010-03-17 15:01:50 +0000[diff] [blame]255 particular, the use of metadata avoids duplicated debugging information from
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]256 the beginning, and the global dead code elimination pass automatically
257 deletes debugging information for a function if it decides to delete the
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]258 function. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]259
260<p>To do this, most of the debugging information (descriptors for types,
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]261 variables, functions, source files, etc) is inserted by the language
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]262 front-end in the form of LLVM metadata. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]263
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]264<p>Debug information is designed to be agnostic about the target debugger and
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]265 debugging information representation (e.g. DWARF/Stabs/etc). It uses a
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]266 generic pass to decode the information that represents variables, types,
267 functions, namespaces, etc: this allows for arbitrary source-language
268 semantics and type-systems to be used, as long as there is a module
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]269 written for the target debugger to interpret the information. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]270
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]271<p>To provide basic functionality, the LLVM debugger does have to make some
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]272 assumptions about the source-level language being debugged, though it keeps
273 these to a minimum. The only common features that the LLVM debugger assumes
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]274 exist are <a href="#format_files">source files</a>,
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]275 and <a href="#format_global_variables">program objects</a>. These abstract
276 objects are used by a debugger to form stack traces, show information about
277 local variables, etc.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]278
279<p>This section of the documentation first describes the representation aspects
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]280 common to any source-language. The <a href="#ccxx_frontend">next section</a>
281 describes the data layout conventions used by the C and C++ front-ends.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]282
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]283<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]284<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]285 <a name="debug_info_descriptors">Debug information descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]286</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]287
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]288<div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]289
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]290<p>In consideration of the complexity and volume of debug information, LLVM
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]291 provides a specification for well formed debug descriptors. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]292
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]293<p>Consumers of LLVM debug information expect the descriptors for program
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]294 objects to start in a canonical format, but the descriptors can include
295 additional information appended at the end that is source-language
296 specific. All LLVM debugging information is versioned, allowing backwards
297 compatibility in the case that the core structures need to change in some
298 way. Also, all debugging information objects start with a tag to indicate
299 what type of object it is. The source-language is allowed to define its own
300 objects, by using unreserved tag numbers. We recommend using with tags in
Benjamin Kramer8040cd32009-10-12 14:46:08 +0000[diff] [blame]301 the range 0x1000 through 0x2000 (there is a defined enum DW_TAG_user_base =
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]302 0x1000.)</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]303
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]304<p>The fields of debug descriptors used internally by LLVM
Nick Lewycky655fd032010-03-31 07:50:17 +0000[diff] [blame]305 are restricted to only the simple data types <tt>i32</tt>, <tt>i1</tt>,
306 <tt>float</tt>, <tt>double</tt>, <tt>mdstring</tt> and <tt>mdnode</tt>. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]307
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]308<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]309<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]310!1 = metadata !{
Nick Lewycky655fd032010-03-31 07:50:17 +0000[diff] [blame]311 i32, ;; A tag
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]312 ...
313}
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]314</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]315</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]316
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]317<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
Nick Lewycky655fd032010-03-31 07:50:17 +0000[diff] [blame]318 <tt>i32</tt> containing a tag value identifying the content of the
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]319 descriptor. The remaining fields are specific to the descriptor. The values
320 of tags are loosely bound to the tag values of DWARF information entries.
321 However, that does not restrict the use of the information supplied to DWARF
322 targets. To facilitate versioning of debug information, the tag is augmented
Nick Lewyckyf3379da2011-07-25 21:13:23 +0000[diff] [blame]323 with the current debug version (LLVMDebugVersion = 8 &lt;&lt; 16 or
324 0x80000 or 524288.)</a></p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]325
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]326<p>The details of the various descriptors follow.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]327
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]328<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]329<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]330 <a name="format_compile_units">Compile unit descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]331</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]332
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]333<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]334
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]335<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]336<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]337!0 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]338 i32, ;; Tag = 17 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]339 ;; (DW_TAG_compile_unit)
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]340 i32, ;; Unused field.
341 i32, ;; DWARF language identifier (ex. DW_LANG_C89)
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]342 metadata, ;; Source file name
343 metadata, ;; Source file directory (includes trailing slash)
344 metadata ;; Producer (ex. "4.0.1 LLVM (LLVM research group)")
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]345 i1, ;; True if this is a main compile unit.
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]346 i1, ;; True if this is optimized.
347 metadata, ;; Flags
348 i32 ;; Runtime version
Devang Patel9b4a2ac2011-09-09 17:07:15 +0000[diff] [blame]349 metadata ;; List of enums types
350 metadata ;; List of retained types
351 metadata ;; List of subprograms
352 metadata ;; List of global variables
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]353}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]354</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]355</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]356
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]357<p>These descriptors contain a source language ID for the file (we use the DWARF
358 3.0 ID numbers, such as <tt>DW_LANG_C89</tt>, <tt>DW_LANG_C_plus_plus</tt>,
359 <tt>DW_LANG_Cobol74</tt>, etc), three strings describing the filename,
360 working directory of the compiler, and an identifier string for the compiler
361 that produced it.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]362
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]363<p>Compile unit descriptors provide the root context for objects declared in a
Devang Patel464f4ef2011-05-03 16:18:28 +0000[diff] [blame]364 specific compilation unit. File descriptors are defined using this context.
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]365 These descriptors are collected by a named metadata
Devang Patel9b4a2ac2011-09-09 17:07:15 +0000[diff] [blame]366 <tt>!llvm.dbg.cu</tt>. Compile unit descriptor keeps track of subprograms,
367 global variables and type information.
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]368
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]369</div>
370
371<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]372<h4>
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]373 <a name="format_files">File descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]374</h4>
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]375
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]376<div>
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]377
378<div class="doc_code">
379<pre>
380!0 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]381 i32, ;; Tag = 41 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]382 ;; (DW_TAG_file_type)
383 metadata, ;; Source file name
384 metadata, ;; Source file directory (includes trailing slash)
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]385 metadata ;; Unused
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]386}
387</pre>
388</div>
389
John Criswellb34500f2010-03-17 15:01:50 +0000[diff] [blame]390<p>These descriptors contain information for a file. Global variables and top
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]391 level functions would be defined using this context.k File descriptors also
392 provide context for source line correspondence. </p>
393
394<p>Each input file is encoded as a separate file descriptor in LLVM debugging
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]395 information output. </p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]396
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]397</div>
398
399<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]400<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]401 <a name="format_global_variables">Global variable descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]402</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]403
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]404<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]405
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]406<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]407<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]408!1 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]409 i32, ;; Tag = 52 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]410 ;; (DW_TAG_variable)
411 i32, ;; Unused field.
412 metadata, ;; Reference to context descriptor
413 metadata, ;; Name
414 metadata, ;; Display name (fully qualified C++ name)
415 metadata, ;; MIPS linkage name (for C++)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]416 metadata, ;; Reference to file where defined
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]417 i32, ;; Line number where defined
418 metadata, ;; Reference to type descriptor
419 i1, ;; True if the global is local to compile unit (static)
420 i1, ;; True if the global is defined in the compile unit (not extern)
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000[diff] [blame]421 {}* ;; Reference to the global variable
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]422}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]423</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]424</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]425
426<p>These descriptors provide debug information about globals variables. The
Devang Patelda6eed32011-03-29 17:27:08 +0000[diff] [blame]427provide details such as name, type and where the variable is defined. All
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]428global variables are collected inside the named metadata
429<tt>!llvm.dbg.cu</tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]430
431</div>
432
433<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]434<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]435 <a name="format_subprograms">Subprogram descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]436</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]437
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]438<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]439
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]440<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]441<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]442!2 = metadata !{
443 i32, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
444 ;; (DW_TAG_subprogram)
445 i32, ;; Unused field.
446 metadata, ;; Reference to context descriptor
447 metadata, ;; Name
448 metadata, ;; Display name (fully qualified C++ name)
449 metadata, ;; MIPS linkage name (for C++)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]450 metadata, ;; Reference to file where defined
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]451 i32, ;; Line number where defined
452 metadata, ;; Reference to type descriptor
453 i1, ;; True if the global is local to compile unit (static)
Devang Patel5e06bb82011-04-22 23:10:17 +0000[diff] [blame]454 i1, ;; True if the global is defined in the compile unit (not extern)
455 i32, ;; Virtuality, e.g. dwarf::DW_VIRTUALITY__virtual
456 i32, ;; Index into a virtual function
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]457 metadata, ;; indicates which base type contains the vtable pointer for the
Devang Patel80ecc152010-06-04 22:49:55 +0000[diff] [blame]458 ;; derived class
Devang Patel473f95f2011-12-16 17:50:04 +0000[diff] [blame]459 i32, ;; Flags - Artifical, Private, Protected, Explicit, Prototyped.
Devang Patel5e06bb82011-04-22 23:10:17 +0000[diff] [blame]460 i1, ;; isOptimized
461 Function *,;; Pointer to LLVM function
462 metadata, ;; Lists function template parameters
463 metadata ;; Function declaration descriptor
Devang Patel93d39be2011-08-19 23:28:12 +0000[diff] [blame]464 metadata ;; List of function variables
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]465}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]466</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]467</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]468
469<p>These descriptors provide debug information about functions, methods and
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]470 subprograms. They provide details such as name, return types and the source
Devang Patelda6eed32011-03-29 17:27:08 +0000[diff] [blame]471 location where the subprogram is defined.
Devang Patelda6eed32011-03-29 17:27:08 +0000[diff] [blame]472</p>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]473
474</div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]475
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]476<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]477<h4>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]478 <a name="format_blocks">Block descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]479</h4>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]480
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]481<div>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]482
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]483<div class="doc_code">
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]484<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]485!3 = metadata !{
Devang Patelc79dda22010-10-04 16:51:59 +0000[diff] [blame]486 i32, ;; Tag = 11 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
Devang Patel7f271fc2010-10-01 22:45:00 +0000[diff] [blame]487 metadata,;; Reference to context descriptor
488 i32, ;; Line number
Devang Patel90d81f12011-03-08 16:25:29 +0000[diff] [blame]489 i32, ;; Column number
490 metadata,;; Reference to source file
491 i32 ;; Unique ID to identify blocks from a template function
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]492}
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]493</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]494</div>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]495
Eric Christopher6618a242011-10-11 22:59:11 +0000[diff] [blame]496<p>This descriptor provides debug information about nested blocks within a
Devang Patel7f271fc2010-10-01 22:45:00 +0000[diff] [blame]497 subprogram. The line number and column numbers are used to dinstinguish
498 two lexical blocks at same depth. </p>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]499
Eric Christopher6618a242011-10-11 22:59:11 +0000[diff] [blame]500<div class="doc_code">
501<pre>
502!3 = metadata !{
503 i32, ;; Tag = 11 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
504 metadata ;; Reference to the scope we're annotating with a file change
505 metadata,;; Reference to the file the scope is enclosed in.
506}
507</pre>
508</div>
509
510<p>This descriptor provides a wrapper around a lexical scope to handle file
511 changes in the middle of a lexical block.</p>
512
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]513</div>
514
515<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]516<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]517 <a name="format_basic_type">Basic type descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]518</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]519
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]520<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]521
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]522<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]523<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]524!4 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]525 i32, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]526 ;; (DW_TAG_base_type)
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]527 metadata, ;; Reference to context
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]528 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]529 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]530 i32, ;; Line number where defined (may be 0)
531 i64, ;; Size in bits
532 i64, ;; Alignment in bits
533 i64, ;; Offset in bits
534 i32, ;; Flags
535 i32 ;; DWARF type encoding
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]536}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]537</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]538</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]539
540<p>These descriptors define primitive types used in the code. Example int, bool
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]541 and float. The context provides the scope of the type, which is usually the
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]542 top level. Since basic types are not usually user defined the context
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]543 and line number can be left as NULL and 0. The size, alignment and offset
544 are expressed in bits and can be 64 bit values. The alignment is used to
545 round the offset when embedded in a
546 <a href="#format_composite_type">composite type</a> (example to keep float
547 doubles on 64 bit boundaries.) The offset is the bit offset if embedded in
548 a <a href="#format_composite_type">composite type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]549
550<p>The type encoding provides the details of the type. The values are typically
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]551 one of the following:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]552
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]553<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]554<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]555DW_ATE_address = 1
556DW_ATE_boolean = 2
557DW_ATE_float = 4
558DW_ATE_signed = 5
559DW_ATE_signed_char = 6
560DW_ATE_unsigned = 7
561DW_ATE_unsigned_char = 8
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]562</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]563</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]564
565</div>
566
567<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]568<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]569 <a name="format_derived_type">Derived type descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]570</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]571
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]572<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]573
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]574<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]575<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]576!5 = metadata !{
577 i32, ;; Tag (see below)
578 metadata, ;; Reference to context
579 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]580 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]581 i32, ;; Line number where defined (may be 0)
Devang Patel0ffd10b2010-10-01 19:19:30 +0000[diff] [blame]582 i64, ;; Size in bits
583 i64, ;; Alignment in bits
584 i64, ;; Offset in bits
Eric Christopher402e12a2011-12-16 23:42:33 +0000[diff] [blame]585 i32, ;; Flags to encode attributes, e.g. private
Devang Patele9db5e22011-04-16 00:11:51 +0000[diff] [blame]586 metadata, ;; Reference to type derived from
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]587 metadata, ;; (optional) Name of the Objective C property associated with
588 ;; Objective-C an ivar
Devang Patele9db5e22011-04-16 00:11:51 +0000[diff] [blame]589 metadata, ;; (optional) Name of the Objective C property getter selector.
590 metadata, ;; (optional) Name of the Objective C property setter selector.
591 i32 ;; (optional) Objective C property attributes.
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]592}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]593</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]594</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]595
596<p>These descriptors are used to define types derived from other types. The
597value of the tag varies depending on the meaning. The following are possible
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]598tag values:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]599
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]600<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]601<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]602DW_TAG_formal_parameter = 5
603DW_TAG_member = 13
604DW_TAG_pointer_type = 15
605DW_TAG_reference_type = 16
606DW_TAG_typedef = 22
607DW_TAG_const_type = 38
608DW_TAG_volatile_type = 53
609DW_TAG_restrict_type = 55
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]610</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]611</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]612
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]613<p><tt>DW_TAG_member</tt> is used to define a member of
614 a <a href="#format_composite_type">composite type</a>
615 or <a href="#format_subprograms">subprogram</a>. The type of the member is
616 the <a href="#format_derived_type">derived
617 type</a>. <tt>DW_TAG_formal_parameter</tt> is used to define a member which
618 is a formal argument of a subprogram.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]619
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]620<p><tt>DW_TAG_typedef</tt> is used to provide a name for the derived type.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]621
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]622<p><tt>DW_TAG_pointer_type</tt>, <tt>DW_TAG_reference_type</tt>,
623 <tt>DW_TAG_const_type</tt>, <tt>DW_TAG_volatile_type</tt> and
Eric Christopheradfc1ef2011-12-16 23:42:35 +0000[diff] [blame]624 <tt>DW_TAG_restrict_type</tt> are used to qualify
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]625 the <a href="#format_derived_type">derived type</a>. </p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]626
627<p><a href="#format_derived_type">Derived type</a> location can be determined
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]628 from the context and line number. The size, alignment and offset are
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]629 expressed in bits and can be 64 bit values. The alignment is used to round
630 the offset when embedded in a <a href="#format_composite_type">composite
631 type</a> (example to keep float doubles on 64 bit boundaries.) The offset is
632 the bit offset if embedded in a <a href="#format_composite_type">composite
633 type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]634
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]635<p>Note that the <tt>void *</tt> type is expressed as a type derived from NULL.
636</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]637
638</div>
639
640<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]641<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]642 <a name="format_composite_type">Composite type descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]643</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]644
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]645<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]646
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]647<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]648<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]649!6 = metadata !{
650 i32, ;; Tag (see below)
651 metadata, ;; Reference to context
652 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]653 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]654 i32, ;; Line number where defined (may be 0)
655 i64, ;; Size in bits
656 i64, ;; Alignment in bits
657 i64, ;; Offset in bits
658 i32, ;; Flags
659 metadata, ;; Reference to type derived from
660 metadata, ;; Reference to array of member descriptors
661 i32 ;; Runtime languages
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]662}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]663</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]664</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]665
666<p>These descriptors are used to define types that are composed of 0 or more
667elements. The value of the tag varies depending on the meaning. The following
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]668are possible tag values:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]669
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]670<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]671<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]672DW_TAG_array_type = 1
673DW_TAG_enumeration_type = 4
674DW_TAG_structure_type = 19
675DW_TAG_union_type = 23
676DW_TAG_vector_type = 259
Bruno Cardoso Lopesd80ddc02009-05-29 17:08:57 +0000[diff] [blame]677DW_TAG_subroutine_type = 21
678DW_TAG_inheritance = 28
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]679</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]680</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]681
Jim Laskeyf8a01a92006-06-15 20:51:43 +0000[diff] [blame]682<p>The vector flag indicates that an array type is a native packed vector.</p>
683
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]684<p>The members of array types (tag = <tt>DW_TAG_array_type</tt>) or vector types
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]685 (tag = <tt>DW_TAG_vector_type</tt>) are <a href="#format_subrange">subrange
686 descriptors</a>, each representing the range of subscripts at that level of
687 indexing.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]688
689<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]690 <a href="#format_enumeration">enumerator descriptors</a>, each representing
Devang Patelda6eed32011-03-29 17:27:08 +0000[diff] [blame]691 the definition of enumeration value for the set. All enumeration type
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]692 descriptors are collected inside the named metadata
693 <tt>!llvm.dbg.cu</tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]694
695<p>The members of structure (tag = <tt>DW_TAG_structure_type</tt>) or union (tag
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]696 = <tt>DW_TAG_union_type</tt>) types are any one of
697 the <a href="#format_basic_type">basic</a>,
698 <a href="#format_derived_type">derived</a>
699 or <a href="#format_composite_type">composite</a> type descriptors, each
700 representing a field member of the structure or union.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]701
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]702<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]703 provide information about base classes, static members and member
704 functions. If a member is a <a href="#format_derived_type">derived type
705 descriptor</a> and has a tag of <tt>DW_TAG_inheritance</tt>, then the type
706 represents a base class. If the member of is
707 a <a href="#format_global_variables">global variable descriptor</a> then it
708 represents a static member. And, if the member is
709 a <a href="#format_subprograms">subprogram descriptor</a> then it represents
710 a member function. For static members and member
711 functions, <tt>getName()</tt> returns the members link or the C++ mangled
712 name. <tt>getDisplayName()</tt> the simplied version of the name.</p>
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]713
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]714<p>The first member of subroutine (tag = <tt>DW_TAG_subroutine_type</tt>) type
715 elements is the return type for the subroutine. The remaining elements are
716 the formal arguments to the subroutine.</p>
Jim Laskey094ee722006-06-20 21:13:20 +0000[diff] [blame]717
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]718<p><a href="#format_composite_type">Composite type</a> location can be
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]719 determined from the context and line number. The size, alignment and
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]720 offset are expressed in bits and can be 64 bit values. The alignment is used
721 to round the offset when embedded in
722 a <a href="#format_composite_type">composite type</a> (as an example, to keep
723 float doubles on 64 bit boundaries.) The offset is the bit offset if embedded
724 in a <a href="#format_composite_type">composite type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]725
726</div>
727
728<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]729<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]730 <a name="format_subrange">Subrange descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]731</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]732
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]733<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]734
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]735<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]736<pre>
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]737!42 = metadata !{
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]738 i32, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
739 i64, ;; Low value
740 i64 ;; High value
741}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]742</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]743</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]744
745<p>These descriptors are used to define ranges of array subscripts for an array
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]746 <a href="#format_composite_type">composite type</a>. The low value defines
747 the lower bounds typically zero for C/C++. The high value is the upper
748 bounds. Values are 64 bit. High - low + 1 is the size of the array. If low
Devang Patel3f932a72011-04-08 23:39:38 +0000[diff] [blame]749 > high the array bounds are not included in generated debugging information.
750</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]751
752</div>
753
754<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]755<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]756 <a name="format_enumeration">Enumerator descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]757</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]758
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]759<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]760
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]761<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]762<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]763!6 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]764 i32, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]765 ;; (DW_TAG_enumerator)
766 metadata, ;; Name
767 i64 ;; Value
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]768}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]769</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]770</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]771
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]772<p>These descriptors are used to define members of an
773 enumeration <a href="#format_composite_type">composite type</a>, it
774 associates the name to the value.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]775
776</div>
777
778<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]779<h4>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]780 <a name="format_variables">Local variables</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]781</h4>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]782
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]783<div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]784
785<div class="doc_code">
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]786<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]787!7 = metadata !{
788 i32, ;; Tag (see below)
789 metadata, ;; Context
790 metadata, ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]791 metadata, ;; Reference to file where defined
Devang Patela83688f2011-03-08 16:29:40 +0000[diff] [blame]792 i32, ;; 24 bit - Line number where defined
793 ;; 8 bit - Argument number. 1 indicates 1st argument.
Devang Patel0a2a3062011-07-27 18:14:50 +0000[diff] [blame]794 metadata, ;; Type descriptor
795 i32, ;; flags
796 metadata ;; (optional) Reference to inline location
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]797}
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]798</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]799</div>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]800
801<p>These descriptors are used to define variables local to a sub program. The
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]802 value of the tag depends on the usage of the variable:</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]803
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]804<div class="doc_code">
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]805<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]806DW_TAG_auto_variable = 256
807DW_TAG_arg_variable = 257
808DW_TAG_return_variable = 258
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]809</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]810</div>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]811
812<p>An auto variable is any variable declared in the body of the function. An
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]813 argument variable is any variable that appears as a formal argument to the
814 function. A return variable is used to track the result of a function and
815 has no source correspondent.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]816
Jim Laskey2d395d92006-03-24 09:20:27 +0000[diff] [blame]817<p>The context is either the subprogram or block where the variable is defined.
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]818 Name the source variable name. Context and line indicate where the
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]819 variable was defined. Type descriptor defines the declared type of the
820 variable.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]821
822</div>
823
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]824</div>
825
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]826<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]827<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]828 <a name="format_common_intrinsics">Debugger intrinsic functions</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]829</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]830
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]831<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]832
833<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]834 provide debug information at various points in generated code.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]835
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]836<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]837<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]838 <a name="format_common_declare">llvm.dbg.declare</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]839</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]840
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]841<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]842<pre>
Devang Patel4c7c0c62010-10-01 19:22:16 +0000[diff] [blame]843 void %<a href="#format_common_declare">llvm.dbg.declare</a>(metadata, metadata)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]844</pre>
845
Chad Rosier5bfd9692012-02-18 01:38:41 +0000[diff] [blame]846<p>This intrinsic provides information about a local element (e.g., variable). The
847 first argument is metadata holding the alloca for the variable. The
848 second argument is metadata containing a description of the variable.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]849</div>
850
851<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]852<h4>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]853 <a name="format_common_value">llvm.dbg.value</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]854</h4>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]855
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]856<div>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]857<pre>
Dan Gohman3dfb3cf2010-05-28 17:07:41 +0000[diff] [blame]858 void %<a href="#format_common_value">llvm.dbg.value</a>(metadata, i64, metadata)
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]859</pre>
860
861<p>This intrinsic provides information when a user source variable is set to a
862 new value. The first argument is the new value (wrapped as metadata). The
863 second argument is the offset in the user source variable where the new value
Chad Rosier5bfd9692012-02-18 01:38:41 +0000[diff] [blame]864 is written. The third argument is metadata containing a description of the
865 user source variable.</p>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]866</div>
867
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]868</div>
869
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]870<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]871<h3>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]872 <a name="format_common_lifetime">Object lifetimes and scoping</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]873</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]874
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]875<div>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]876<p>In many languages, the local variables in functions can have their lifetimes
877 or scopes limited to a subset of a function. In the C family of languages,
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]878 for example, variables are only live (readable and writable) within the
879 source block that they are defined in. In functional languages, values are
880 only readable after they have been defined. Though this is a very obvious
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]881 concept, it is non-trivial to model in LLVM, because it has no notion of
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]882 scoping in this sense, and does not want to be tied to a language's scoping
883 rules.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]884
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]885<p>In order to handle this, the LLVM debug format uses the metadata attached to
Nick Lewycky655fd032010-03-31 07:50:17 +0000[diff] [blame]886 llvm instructions to encode line number and scoping information. Consider
887 the following C fragment, for example:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]888
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]889<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]890<pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8911. void foo() {
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]8922. int X = 21;
8933. int Y = 22;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8944. {
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]8955. int Z = 23;
8966. Z = X;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8977. }
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]8988. X = Y;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8999. }
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]900</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]901</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]902
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]903<p>Compiled to LLVM, this function would be represented like this:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]904
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]905<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]906<pre>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]907define void @foo() nounwind ssp {
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]908entry:
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]909 %X = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
910 %Y = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
911 %Z = alloca i32, align 4 ; &lt;i32*&gt; [#uses=3]
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000[diff] [blame]912 %0 = bitcast i32* %X to {}* ; &lt;{}*&gt; [#uses=1]
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]913 call void @llvm.dbg.declare(metadata !{i32 * %X}, metadata !0), !dbg !7
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]914 store i32 21, i32* %X, !dbg !8
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000[diff] [blame]915 %1 = bitcast i32* %Y to {}* ; &lt;{}*&gt; [#uses=1]
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]916 call void @llvm.dbg.declare(metadata !{i32 * %Y}, metadata !9), !dbg !10
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]917 store i32 22, i32* %Y, !dbg !11
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000[diff] [blame]918 %2 = bitcast i32* %Z to {}* ; &lt;{}*&gt; [#uses=1]
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]919 call void @llvm.dbg.declare(metadata !{i32 * %Z}, metadata !12), !dbg !14
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]920 store i32 23, i32* %Z, !dbg !15
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]921 %tmp = load i32* %X, !dbg !16 ; &lt;i32&gt; [#uses=1]
922 %tmp1 = load i32* %Y, !dbg !16 ; &lt;i32&gt; [#uses=1]
923 %add = add nsw i32 %tmp, %tmp1, !dbg !16 ; &lt;i32&gt; [#uses=1]
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]924 store i32 %add, i32* %Z, !dbg !16
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]925 %tmp2 = load i32* %Y, !dbg !17 ; &lt;i32&gt; [#uses=1]
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]926 store i32 %tmp2, i32* %X, !dbg !17
927 ret void, !dbg !18
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]928}
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]929
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]930declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]931
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]932!0 = metadata !{i32 459008, metadata !1, metadata !"X",
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]933 metadata !3, i32 2, metadata !6}; [ DW_TAG_auto_variable ]
934!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]935!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo", metadata !"foo",
936 metadata !"foo", metadata !3, i32 1, metadata !4,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]937 i1 false, i1 true}; [DW_TAG_subprogram ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]938!3 = metadata !{i32 458769, i32 0, i32 12, metadata !"foo.c",
939 metadata !"/private/tmp", metadata !"clang 1.1", i1 true,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]940 i1 false, metadata !"", i32 0}; [DW_TAG_compile_unit ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]941!4 = metadata !{i32 458773, metadata !3, metadata !"", null, i32 0, i64 0, i64 0,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]942 i64 0, i32 0, null, metadata !5, i32 0}; [DW_TAG_subroutine_type ]
943!5 = metadata !{null}
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]944!6 = metadata !{i32 458788, metadata !3, metadata !"int", metadata !3, i32 0,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]945 i64 32, i64 32, i64 0, i32 0, i32 5}; [DW_TAG_base_type ]
946!7 = metadata !{i32 2, i32 7, metadata !1, null}
947!8 = metadata !{i32 2, i32 3, metadata !1, null}
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]948!9 = metadata !{i32 459008, metadata !1, metadata !"Y", metadata !3, i32 3,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]949 metadata !6}; [ DW_TAG_auto_variable ]
950!10 = metadata !{i32 3, i32 7, metadata !1, null}
951!11 = metadata !{i32 3, i32 3, metadata !1, null}
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]952!12 = metadata !{i32 459008, metadata !13, metadata !"Z", metadata !3, i32 5,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]953 metadata !6}; [ DW_TAG_auto_variable ]
954!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
955!14 = metadata !{i32 5, i32 9, metadata !13, null}
956!15 = metadata !{i32 5, i32 5, metadata !13, null}
957!16 = metadata !{i32 6, i32 5, metadata !13, null}
958!17 = metadata !{i32 8, i32 3, metadata !1, null}
959!18 = metadata !{i32 9, i32 1, metadata !2, null}
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]960</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]961</div>
962
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]963<p>This example illustrates a few important details about LLVM debugging
964 information. In particular, it shows how the <tt>llvm.dbg.declare</tt>
965 intrinsic and location information, which are attached to an instruction,
966 are applied together to allow a debugger to analyze the relationship between
967 statements, variable definitions, and the code used to implement the
968 function.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]969
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]970<div class="doc_code">
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]971<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]972call void @llvm.dbg.declare(metadata, metadata !0), !dbg !7
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]973</pre>
974</div>
975
976<p>The first intrinsic
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]977 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]978 encodes debugging information for the variable <tt>X</tt>. The metadata
979 <tt>!dbg !7</tt> attached to the intrinsic provides scope information for the
980 variable <tt>X</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]981
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]982<div class="doc_code">
983<pre>
984!7 = metadata !{i32 2, i32 7, metadata !1, null}
985!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]986!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo",
987 metadata !"foo", metadata !"foo", metadata !3, i32 1,
988 metadata !4, i1 false, i1 true}; [DW_TAG_subprogram ]
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]989</pre>
990</div>
991
992<p>Here <tt>!7</tt> is metadata providing location information. It has four
993 fields: line number, column number, scope, and original scope. The original
994 scope represents inline location if this instruction is inlined inside a
995 caller, and is null otherwise. In this example, scope is encoded by
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]996 <tt>!1</tt>. <tt>!1</tt> represents a lexical block inside the scope
997 <tt>!2</tt>, where <tt>!2</tt> is a
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]998 <a href="#format_subprograms">subprogram descriptor</a>. This way the
999 location information attached to the intrinsics indicates that the
1000 variable <tt>X</tt> is declared at line number 2 at a function level scope in
1001 function <tt>foo</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1002
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]1003<p>Now lets take another example.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1004
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1005<div class="doc_code">
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]1006<pre>
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]1007call void @llvm.dbg.declare(metadata, metadata !12), !dbg !14
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1008</pre>
1009</div>
1010
1011<p>The second intrinsic
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]1012 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1013 encodes debugging information for variable <tt>Z</tt>. The metadata
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1014 <tt>!dbg !14</tt> attached to the intrinsic provides scope information for
1015 the variable <tt>Z</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1016
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1017<div class="doc_code">
1018<pre>
1019!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
1020!14 = metadata !{i32 5, i32 9, metadata !13, null}
1021</pre>
1022</div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1023
John Criswellb34500f2010-03-17 15:01:50 +0000[diff] [blame]1024<p>Here <tt>!14</tt> indicates that <tt>Z</tt> is declared at line number 5 and
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1025 column number 9 inside of lexical scope <tt>!13</tt>. The lexical scope
1026 itself resides inside of lexical scope <tt>!1</tt> described above.</p>
1027
1028<p>The scope information attached with each instruction provides a
1029 straightforward way to find instructions covered by a scope.</p>
1030
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1031</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1032
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1033</div>
1034
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1035<!-- *********************************************************************** -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1036<h2>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1037 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1038</h2>
Misha Brukman94218a72004-12-09 20:27:37 +0000[diff] [blame]1039<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1040
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1041<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1042
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1043<p>The C and C++ front-ends represent information about the program in a format
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1044 that is effectively identical
1045 to <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3.0</a> in
1046 terms of information content. This allows code generators to trivially
1047 support native debuggers by generating standard dwarf information, and
1048 contains enough information for non-dwarf targets to translate it as
1049 needed.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1050
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1051<p>This section describes the forms used to represent C and C++ programs. Other
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1052 languages could pattern themselves after this (which itself is tuned to
1053 representing programs in the same way that DWARF 3 does), or they could
1054 choose to provide completely different forms if they don't fit into the DWARF
1055 model. As support for debugging information gets added to the various LLVM
1056 source-language front-ends, the information used should be documented
1057 here.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1058
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1059<p>The following sections provide examples of various C/C++ constructs and the
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1060 debug information that would best describe those constructs.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1061
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1062<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1063<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1064 <a name="ccxx_compile_units">C/C++ source file information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1065</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1066
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1067<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1068
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1069<p>Given the source files <tt>MySource.cpp</tt> and <tt>MyHeader.h</tt> located
1070 in the directory <tt>/Users/mine/sources</tt>, the following code:</p>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1071
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1072<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1073<pre>
1074#include "MyHeader.h"
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1075
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1076int main(int argc, char *argv[]) {
1077 return 0;
1078}
1079</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1080</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1081
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1082<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1083
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1084<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1085<pre>
1086...
1087;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1088;; Define the compile unit for the main source file "/Users/mine/sources/MySource.cpp".
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1089;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1090!2 = metadata !{
1091 i32 524305, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1092 i32 0, ;; Unused
1093 i32 4, ;; Language Id
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1094 metadata !"MySource.cpp",
1095 metadata !"/Users/mine/sources",
1096 metadata !"4.2.1 (Based on Apple Inc. build 5649) (LLVM build 00)",
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1097 i1 true, ;; Main Compile Unit
1098 i1 false, ;; Optimized compile unit
1099 metadata !"", ;; Compiler flags
1100 i32 0} ;; Runtime version
1101
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1102;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1103;; Define the file for the file "/Users/mine/sources/MySource.cpp".
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1104;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1105!1 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1106 i32 524329, ;; Tag
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1107 metadata !"MySource.cpp",
1108 metadata !"/Users/mine/sources",
Devang Patel9fea9c22010-07-13 16:53:20 +0000[diff] [blame]1109 metadata !2 ;; Compile unit
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1110}
1111
1112;;
1113;; Define the file for the file "/Users/mine/sources/Myheader.h"
1114;;
1115!3 = metadata !{
1116 i32 524329, ;; Tag
1117 metadata !"Myheader.h"
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1118 metadata !"/Users/mine/sources",
Devang Patel9fea9c22010-07-13 16:53:20 +0000[diff] [blame]1119 metadata !2 ;; Compile unit
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1120}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1121
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1122...
1123</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1124</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1125
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1126<p>llvm::Instruction provides easy access to metadata attached with an
Devang Pateld98ec5f2010-03-26 19:08:36 +0000[diff] [blame]1127instruction. One can extract line number information encoded in LLVM IR
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1128using <tt>Instruction::getMetadata()</tt> and
Devang Pateld98ec5f2010-03-26 19:08:36 +0000[diff] [blame]1129<tt>DILocation::getLineNumber()</tt>.
1130<pre>
1131 if (MDNode *N = I->getMetadata("dbg")) { // Here I is an LLVM instruction
1132 DILocation Loc(N); // DILocation is in DebugInfo.h
1133 unsigned Line = Loc.getLineNumber();
1134 StringRef File = Loc.getFilename();
1135 StringRef Dir = Loc.getDirectory();
1136 }
1137</pre>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1138</div>
1139
1140<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1141<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1142 <a name="ccxx_global_variable">C/C++ global variable information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1143</h3>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1144
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1145<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1146
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1147<p>Given an integer global variable declared as follows:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1148
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1149<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1150<pre>
1151int MyGlobal = 100;
1152</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1153</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1154
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1155<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1156
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1157<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1158<pre>
1159;;
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1160;; Define the global itself.
1161;;
1162%MyGlobal = global int 100
1163...
1164;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1165;; List of debug info of globals
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1166;;
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]1167!llvm.dbg.cu = !{!0}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1168
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]1169;; Define the compile unit.
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1170!0 = metadata !{
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]1171 i32 786449, ;; Tag
1172 i32 0, ;; Context
1173 i32 4, ;; Language
1174 metadata !"foo.cpp", ;; File
1175 metadata !"/Volumes/Data/tmp", ;; Directory
1176 metadata !"clang version 3.1 ", ;; Producer
1177 i1 true, ;; Deprecated field
1178 i1 false, ;; "isOptimized"?
1179 metadata !"", ;; Flags
1180 i32 0, ;; Runtime Version
1181 metadata !1, ;; Enum Types
1182 metadata !1, ;; Retained Types
1183 metadata !1, ;; Subprograms
1184 metadata !3 ;; Global Variables
1185} ; [ DW_TAG_compile_unit ]
1186
1187;; The Array of Global Variables
1188!3 = metadata !{
1189 metadata !4
1190}
1191
1192!4 = metadata !{
1193 metadata !5
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1194}
1195
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1196;;
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]1197;; Define the global variable itself.
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1198;;
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]1199!5 = metadata !{
1200 i32 786484, ;; Tag
1201 i32 0, ;; Unused
1202 null, ;; Unused
1203 metadata !"MyGlobal", ;; Name
1204 metadata !"MyGlobal", ;; Display Name
1205 metadata !"", ;; Linkage Name
1206 metadata !6, ;; File
1207 i32 1, ;; Line
1208 metadata !7, ;; Type
1209 i32 0, ;; IsLocalToUnit
1210 i32 1, ;; IsDefinition
1211 i32* @MyGlobal ;; LLVM-IR Value
1212} ; [ DW_TAG_variable ]
1213
1214;;
1215;; Define the file
1216;;
1217!6 = metadata !{
1218 i32 786473, ;; Tag
1219 metadata !"foo.cpp", ;; File
1220 metadata !"/Volumes/Data/tmp", ;; Directory
1221 null ;; Unused
1222} ; [ DW_TAG_file_type ]
1223
1224;;
1225;; Define the type
1226;;
1227!7 = metadata !{
1228 i32 786468, ;; Tag
1229 null, ;; Unused
1230 metadata !"int", ;; Name
1231 null, ;; Unused
1232 i32 0, ;; Line
1233 i64 32, ;; Size in Bits
1234 i64 32, ;; Align in Bits
1235 i64 0, ;; Offset
1236 i32 0, ;; Flags
1237 i32 5 ;; Encoding
1238} ; [ DW_TAG_base_type ]
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1239
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1240</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1241</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1242
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1243</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1244
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1245<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1246<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1247 <a name="ccxx_subprogram">C/C++ function information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1248</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1249
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1250<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1251
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1252<p>Given a function declared as follows:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1253
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1254<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1255<pre>
1256int main(int argc, char *argv[]) {
1257 return 0;
1258}
1259</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1260</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1261
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1262<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1263
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1264<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1265<pre>
1266;;
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1267;; Define the anchor for subprograms. Note that the second field of the
1268;; anchor is 46, which is the same as the tag for subprograms
1269;; (46 = DW_TAG_subprogram.)
1270;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1271!6 = metadata !{
1272 i32 524334, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1273 i32 0, ;; Unused
1274 metadata !1, ;; Context
1275 metadata !"main", ;; Name
1276 metadata !"main", ;; Display name
1277 metadata !"main", ;; Linkage name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1278 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1279 i32 1, ;; Line number
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1280 metadata !4, ;; Type
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1281 i1 false, ;; Is local
Devang Patelda194752011-04-05 22:52:06 +0000[diff] [blame]1282 i1 true, ;; Is definition
1283 i32 0, ;; Virtuality attribute, e.g. pure virtual function
1284 i32 0, ;; Index into virtual table for C++ methods
1285 i32 0, ;; Type that holds virtual table.
1286 i32 0, ;; Flags
1287 i1 false, ;; True if this function is optimized
1288 Function *, ;; Pointer to llvm::Function
1289 null ;; Function template parameters
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1290}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1291;;
1292;; Define the subprogram itself.
1293;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1294define i32 @main(i32 %argc, i8** %argv) {
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1295...
1296}
1297</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1298</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1299
1300</div>
1301
1302<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1303<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1304 <a name="ccxx_basic_types">C/C++ basic types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1305</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1306
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1307<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1308
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1309<p>The following are the basic type descriptors for C/C++ core types:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1310
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1311<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1312<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1313 <a name="ccxx_basic_type_bool">bool</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1314</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1315
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1316<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1317
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1318<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1319<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1320!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1321 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1322 metadata !1, ;; Context
1323 metadata !"bool", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1324 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1325 i32 0, ;; Line number
1326 i64 8, ;; Size in Bits
1327 i64 8, ;; Align in Bits
1328 i64 0, ;; Offset in Bits
1329 i32 0, ;; Flags
1330 i32 2 ;; Encoding
1331}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1332</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1333</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1334
1335</div>
1336
1337<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1338<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1339 <a name="ccxx_basic_char">char</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1340</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1341
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1342<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1343
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1344<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1345<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1346!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1347 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1348 metadata !1, ;; Context
1349 metadata !"char", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1350 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1351 i32 0, ;; Line number
1352 i64 8, ;; Size in Bits
1353 i64 8, ;; Align in Bits
1354 i64 0, ;; Offset in Bits
1355 i32 0, ;; Flags
1356 i32 6 ;; Encoding
1357}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1358</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1359</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1360
1361</div>
1362
1363<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1364<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1365 <a name="ccxx_basic_unsigned_char">unsigned char</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1366</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1367
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1368<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1369
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1370<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1371<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1372!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1373 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1374 metadata !1, ;; Context
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1375 metadata !"unsigned char",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1376 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1377 i32 0, ;; Line number
1378 i64 8, ;; Size in Bits
1379 i64 8, ;; Align in Bits
1380 i64 0, ;; Offset in Bits
1381 i32 0, ;; Flags
1382 i32 8 ;; Encoding
1383}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1384</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1385</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1386
1387</div>
1388
1389<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1390<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1391 <a name="ccxx_basic_short">short</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1392</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1393
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1394<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1395
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1396<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1397<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1398!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1399 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1400 metadata !1, ;; Context
1401 metadata !"short int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1402 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1403 i32 0, ;; Line number
1404 i64 16, ;; Size in Bits
1405 i64 16, ;; Align in Bits
1406 i64 0, ;; Offset in Bits
1407 i32 0, ;; Flags
1408 i32 5 ;; Encoding
1409}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1410</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1411</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1412
1413</div>
1414
1415<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1416<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1417 <a name="ccxx_basic_unsigned_short">unsigned short</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1418</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1419
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1420<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1421
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1422<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1423<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1424!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1425 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1426 metadata !1, ;; Context
1427 metadata !"short unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1428 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1429 i32 0, ;; Line number
1430 i64 16, ;; Size in Bits
1431 i64 16, ;; Align in Bits
1432 i64 0, ;; Offset in Bits
1433 i32 0, ;; Flags
1434 i32 7 ;; Encoding
1435}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1436</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1437</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1438
1439</div>
1440
1441<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1442<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1443 <a name="ccxx_basic_int">int</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1444</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1445
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1446<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1447
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1448<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1449<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1450!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1451 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1452 metadata !1, ;; Context
1453 metadata !"int", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1454 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1455 i32 0, ;; Line number
1456 i64 32, ;; Size in Bits
1457 i64 32, ;; Align in Bits
1458 i64 0, ;; Offset in Bits
1459 i32 0, ;; Flags
1460 i32 5 ;; Encoding
1461}
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1462</pre></div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1463
1464</div>
1465
1466<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1467<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1468 <a name="ccxx_basic_unsigned_int">unsigned int</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1469</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1470
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1471<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1472
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1473<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1474<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1475!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1476 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1477 metadata !1, ;; Context
1478 metadata !"unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1479 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1480 i32 0, ;; Line number
1481 i64 32, ;; Size in Bits
1482 i64 32, ;; Align in Bits
1483 i64 0, ;; Offset in Bits
1484 i32 0, ;; Flags
1485 i32 7 ;; Encoding
1486}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1487</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1488</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1489
1490</div>
1491
1492<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1493<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1494 <a name="ccxx_basic_long_long">long long</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1495</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1496
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1497<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1498
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1499<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1500<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1501!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1502 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1503 metadata !1, ;; Context
1504 metadata !"long long int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1505 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1506 i32 0, ;; Line number
1507 i64 64, ;; Size in Bits
1508 i64 64, ;; Align in Bits
1509 i64 0, ;; Offset in Bits
1510 i32 0, ;; Flags
1511 i32 5 ;; Encoding
1512}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1513</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1514</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1515
1516</div>
1517
1518<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1519<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1520 <a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1521</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1522
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1523<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1524
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1525<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1526<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1527!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1528 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1529 metadata !1, ;; Context
1530 metadata !"long long unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1531 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1532 i32 0, ;; Line number
1533 i64 64, ;; Size in Bits
1534 i64 64, ;; Align in Bits
1535 i64 0, ;; Offset in Bits
1536 i32 0, ;; Flags
1537 i32 7 ;; Encoding
1538}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1539</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1540</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1541
1542</div>
1543
1544<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1545<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1546 <a name="ccxx_basic_float">float</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1547</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1548
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1549<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1550
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1551<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1552<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1553!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1554 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1555 metadata !1, ;; Context
1556 metadata !"float",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1557 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1558 i32 0, ;; Line number
1559 i64 32, ;; Size in Bits
1560 i64 32, ;; Align in Bits
1561 i64 0, ;; Offset in Bits
1562 i32 0, ;; Flags
1563 i32 4 ;; Encoding
1564}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1565</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1566</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1567
1568</div>
1569
1570<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1571<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1572 <a name="ccxx_basic_double">double</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1573</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1574
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1575<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1576
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1577<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1578<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1579!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1580 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1581 metadata !1, ;; Context
1582 metadata !"double",;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1583 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1584 i32 0, ;; Line number
1585 i64 64, ;; Size in Bits
1586 i64 64, ;; Align in Bits
1587 i64 0, ;; Offset in Bits
1588 i32 0, ;; Flags
1589 i32 4 ;; Encoding
1590}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1591</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1592</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1593
1594</div>
1595
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1596</div>
1597
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1598<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1599<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1600 <a name="ccxx_derived_types">C/C++ derived types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1601</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1602
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1603<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1604
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1605<p>Given the following as an example of C/C++ derived type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1606
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1607<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1608<pre>
1609typedef const int *IntPtr;
1610</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1611</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1612
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1613<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1614
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1615<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1616<pre>
1617;;
1618;; Define the typedef "IntPtr".
1619;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1620!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1621 i32 524310, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1622 metadata !1, ;; Context
1623 metadata !"IntPtr", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1624 metadata !3, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1625 i32 0, ;; Line number
1626 i64 0, ;; Size in bits
1627 i64 0, ;; Align in bits
1628 i64 0, ;; Offset in bits
1629 i32 0, ;; Flags
1630 metadata !4 ;; Derived From type
1631}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1632
1633;;
1634;; Define the pointer type.
1635;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1636!4 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1637 i32 524303, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1638 metadata !1, ;; Context
1639 metadata !"", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1640 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1641 i32 0, ;; Line number
1642 i64 64, ;; Size in bits
1643 i64 64, ;; Align in bits
1644 i64 0, ;; Offset in bits
1645 i32 0, ;; Flags
1646 metadata !5 ;; Derived From type
1647}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1648;;
1649;; Define the const type.
1650;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1651!5 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1652 i32 524326, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1653 metadata !1, ;; Context
1654 metadata !"", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1655 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1656 i32 0, ;; Line number
1657 i64 32, ;; Size in bits
1658 i64 32, ;; Align in bits
1659 i64 0, ;; Offset in bits
1660 i32 0, ;; Flags
1661 metadata !6 ;; Derived From type
1662}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1663;;
1664;; Define the int type.
1665;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1666!6 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1667 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1668 metadata !1, ;; Context
1669 metadata !"int", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1670 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1671 i32 0, ;; Line number
1672 i64 32, ;; Size in bits
1673 i64 32, ;; Align in bits
1674 i64 0, ;; Offset in bits
1675 i32 0, ;; Flags
1676 5 ;; Encoding
1677}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1678</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1679</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1680
1681</div>
1682
1683<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1684<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1685 <a name="ccxx_composite_types">C/C++ struct/union types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1686</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1687
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1688<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1689
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1690<p>Given the following as an example of C/C++ struct type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1691
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1692<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1693<pre>
1694struct Color {
1695 unsigned Red;
1696 unsigned Green;
1697 unsigned Blue;
1698};
1699</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1700</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1701
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1702<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1703
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1704<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1705<pre>
1706;;
1707;; Define basic type for unsigned int.
1708;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1709!5 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1710 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1711 metadata !1, ;; Context
1712 metadata !"unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1713 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1714 i32 0, ;; Line number
1715 i64 32, ;; Size in Bits
1716 i64 32, ;; Align in Bits
1717 i64 0, ;; Offset in Bits
1718 i32 0, ;; Flags
1719 i32 7 ;; Encoding
1720}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1721;;
1722;; Define composite type for struct Color.
1723;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1724!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1725 i32 524307, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1726 metadata !1, ;; Context
1727 metadata !"Color", ;; Name
1728 metadata !1, ;; Compile unit
1729 i32 1, ;; Line number
1730 i64 96, ;; Size in bits
1731 i64 32, ;; Align in bits
1732 i64 0, ;; Offset in bits
1733 i32 0, ;; Flags
1734 null, ;; Derived From
1735 metadata !3, ;; Elements
1736 i32 0 ;; Runtime Language
1737}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1738
1739;;
1740;; Define the Red field.
1741;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1742!4 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1743 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1744 metadata !1, ;; Context
1745 metadata !"Red", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1746 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1747 i32 2, ;; Line number
1748 i64 32, ;; Size in bits
1749 i64 32, ;; Align in bits
1750 i64 0, ;; Offset in bits
1751 i32 0, ;; Flags
1752 metadata !5 ;; Derived From type
1753}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1754
1755;;
1756;; Define the Green field.
1757;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1758!6 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1759 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1760 metadata !1, ;; Context
1761 metadata !"Green", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1762 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1763 i32 3, ;; Line number
1764 i64 32, ;; Size in bits
1765 i64 32, ;; Align in bits
1766 i64 32, ;; Offset in bits
1767 i32 0, ;; Flags
1768 metadata !5 ;; Derived From type
1769}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1770
1771;;
1772;; Define the Blue field.
1773;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1774!7 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1775 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1776 metadata !1, ;; Context
1777 metadata !"Blue", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1778 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1779 i32 4, ;; Line number
1780 i64 32, ;; Size in bits
1781 i64 32, ;; Align in bits
1782 i64 64, ;; Offset in bits
1783 i32 0, ;; Flags
1784 metadata !5 ;; Derived From type
1785}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1786
1787;;
1788;; Define the array of fields used by the composite type Color.
1789;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1790!3 = metadata !{metadata !4, metadata !6, metadata !7}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1791</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1792</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1793
1794</div>
1795
1796<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1797<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1798 <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1799</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1800
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1801<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1802
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1803<p>Given the following as an example of C/C++ enumeration type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1804
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1805<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1806<pre>
1807enum Trees {
1808 Spruce = 100,
1809 Oak = 200,
1810 Maple = 300
1811};
1812</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1813</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1814
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1815<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1816
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1817<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1818<pre>
1819;;
1820;; Define composite type for enum Trees
1821;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1822!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1823 i32 524292, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1824 metadata !1, ;; Context
1825 metadata !"Trees", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1826 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1827 i32 1, ;; Line number
1828 i64 32, ;; Size in bits
1829 i64 32, ;; Align in bits
1830 i64 0, ;; Offset in bits
1831 i32 0, ;; Flags
1832 null, ;; Derived From type
1833 metadata !3, ;; Elements
1834 i32 0 ;; Runtime language
1835}
Devang Patel2a610c72009-08-25 05:24:07 +0000[diff] [blame]1836
Devang Patel82459882009-08-26 05:01:18 +0000[diff] [blame]1837;;
1838;; Define the array of enumerators used by composite type Trees.
1839;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1840!3 = metadata !{metadata !4, metadata !5, metadata !6}
1841
1842;;
1843;; Define Spruce enumerator.
1844;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1845!4 = metadata !{i32 524328, metadata !"Spruce", i64 100}
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1846
1847;;
1848;; Define Oak enumerator.
1849;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1850!5 = metadata !{i32 524328, metadata !"Oak", i64 200}
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1851
1852;;
1853;; Define Maple enumerator.
1854;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1855!6 = metadata !{i32 524328, metadata !"Maple", i64 300}
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1856
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1857</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1858</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1859
1860</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1861
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1862</div>
1863
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1864
1865<!-- *********************************************************************** -->
1866<h2>
1867 <a name="llvmdwarfextension">Debugging information format</a>
1868</h2>
1869<!-- *********************************************************************** -->
1870<div>
1871<!-- ======================================================================= -->
1872<h3>
Bill Wendling0eb59142012-03-06 09:17:39 +0000[diff] [blame]1873 <a name="objcproperty">Debugging Information Extension for Objective C Properties</a>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1874</h3>
1875<div>
1876<!-- *********************************************************************** -->
1877<h4>
1878 <a name="objcpropertyintroduction">Introduction</a>
1879</h4>
1880<!-- *********************************************************************** -->
1881
1882<div>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1883<p>Objective C provides a simpler way to declare and define accessor methods
1884using declared properties. The language provides features to declare a
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1885property and to let compiler synthesize accessor methods.
1886</p>
1887
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1888<p>The debugger lets developer inspect Objective C interfaces and their
1889instance variables and class variables. However, the debugger does not know
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1890anything about the properties defined in Objective C interfaces. The debugger
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1891consumes information generated by compiler in DWARF format. The format does
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1892not support encoding of Objective C properties. This proposal describes DWARF
1893extensions to encode Objective C properties, which the debugger can use to let
1894developers inspect Objective C properties.
1895</p>
1896
1897</div>
1898
1899
1900<!-- *********************************************************************** -->
1901<h4>
1902 <a name="objcpropertyproposal">Proposal</a>
1903</h4>
1904<!-- *********************************************************************** -->
1905
1906<div>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1907<p>Objective C properties exist separately from class members. A property
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1908can be defined only by &quot;setter&quot; and &quot;getter&quot; selectors, and
1909be calculated anew on each access. Or a property can just be a direct access
1910to some declared ivar. Finally it can have an ivar &quot;automatically
1911synthesized&quot; for it by the compiler, in which case the property can be
1912referred to in user code directly using the standard C dereference syntax as
1913well as through the property &quot;dot&quot; syntax, but there is no entry in
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1914the @interface declaration corresponding to this ivar.
1915</p>
1916<p>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1917To facilitate debugging, these properties we will add a new DWARF TAG into the
1918DW_TAG_structure_type definition for the class to hold the description of a
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1919given property, and a set of DWARF attributes that provide said description.
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1920The property tag will also contain the name and declared type of the property.
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1921</p>
1922<p>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1923If there is a related ivar, there will also be a DWARF property attribute placed
1924in the DW_TAG_member DIE for that ivar referring back to the property TAG for
1925that property. And in the case where the compiler synthesizes the ivar directly,
1926the compiler is expected to generate a DW_TAG_member for that ivar (with the
1927DW_AT_artificial set to 1), whose name will be the name used to access this
1928ivar directly in code, and with the property attribute pointing back to the
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1929property it is backing.
1930</p>
1931<p>
1932The following examples will serve as illustration for our discussion:
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1933</p>
1934
1935<div class="doc_code">
1936<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1937@interface I1 {
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1938 int n2;
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1939}
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1940
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1941@property int p1;
1942@property int p2;
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1943@end
1944
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1945@implementation I1
1946@synthesize p1;
1947@synthesize p2 = n2;
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1948@end
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1949</pre>
1950</div>
1951
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1952<p>
1953This produces the following DWARF (this is a &quot;pseudo dwarfdump&quot; output):
1954</p>
1955<div class="doc_code">
1956<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]19570x00000100: TAG_structure_type [7] *
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1958 AT_APPLE_runtime_class( 0x10 )
1959 AT_name( "I1" )
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1960 AT_decl_file( "Objc_Property.m" )
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1961 AT_decl_line( 3 )
1962
19630x00000110 TAG_APPLE_property
1964 AT_name ( "p1" )
1965 AT_type ( {0x00000150} ( int ) )
1966
19670x00000120: TAG_APPLE_property
1968 AT_name ( "p2" )
1969 AT_type ( {0x00000150} ( int ) )
1970
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]19710x00000130: TAG_member [8]
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1972 AT_name( "_p1" )
1973 AT_APPLE_property ( {0x00000110} "p1" )
1974 AT_type( {0x00000150} ( int ) )
1975 AT_artificial ( 0x1 )
1976
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]19770x00000140: TAG_member [8]
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1978 AT_name( "n2" )
1979 AT_APPLE_property ( {0x00000120} "p2" )
1980 AT_type( {0x00000150} ( int ) )
1981
19820x00000150: AT_type( ( int ) )
1983</pre>
1984</div>
1985
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1986<p> Note, the current convention is that the name of the ivar for an
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1987auto-synthesized property is the name of the property from which it derives with
1988an underscore prepended, as is shown in the example.
1989But we actually don't need to know this convention, since we are given the name
1990of the ivar directly.
1991</p>
1992
1993<p>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1994Also, it is common practice in ObjC to have different property declarations in
1995the @interface and @implementation - e.g. to provide a read-only property in
1996the interface,and a read-write interface in the implementation. In that case,
1997the compiler should emit whichever property declaration will be in force in the
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1998current translation unit.
1999</p>
2000
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2001<p> Developers can decorate a property with attributes which are encoded using
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2002DW_AT_APPLE_property_attribute.
2003</p>
2004
2005<div class="doc_code">
2006<pre>
2007@property (readonly, nonatomic) int pr;
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2008</pre>
2009</div>
2010<p>
2011Which produces a property tag:
2012<p>
2013<div class="doc_code">
2014<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2015TAG_APPLE_property [8]
2016 AT_name( "pr" )
2017 AT_type ( {0x00000147} (int) )
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2018 AT_APPLE_property_attribute (DW_APPLE_PROPERTY_readonly, DW_APPLE_PROPERTY_nonatomic)
2019</pre>
2020</div>
2021
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2022<p> The setter and getter method names are attached to the property using
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2023DW_AT_APPLE_property_setter and DW_AT_APPLE_property_getter attributes.
2024</p>
2025<div class="doc_code">
2026<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2027@interface I1
2028@property (setter=myOwnP3Setter:) int p3;
2029-(void)myOwnP3Setter:(int)a;
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2030@end
2031
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2032@implementation I1
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2033@synthesize p3;
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2034-(void)myOwnP3Setter:(int)a{ }
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2035@end
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2036</pre>
2037</div>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2038
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2039<p>
2040The DWARF for this would be:
2041</p>
2042<div class="doc_code">
2043<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]20440x000003bd: TAG_structure_type [7] *
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2045 AT_APPLE_runtime_class( 0x10 )
2046 AT_name( "I1" )
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2047 AT_decl_file( "Objc_Property.m" )
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2048 AT_decl_line( 3 )
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2049
20500x000003cd TAG_APPLE_property
2051 AT_name ( "p3" )
2052 AT_APPLE_property_setter ( "myOwnP3Setter:" )
2053 AT_type( {0x00000147} ( int ) )
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2054
20550x000003f3: TAG_member [8]
2056 AT_name( "_p3" )
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2057 AT_type ( {0x00000147} ( int ) )
2058 AT_APPLE_property ( {0x000003cd} )
2059 AT_artificial ( 0x1 )
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2060</pre>
2061</div>
2062
2063</div>
2064
2065<!-- *********************************************************************** -->
2066<h4>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2067 <a name="objcpropertynewtags">New DWARF Tags</a>
2068</h4>
2069<!-- *********************************************************************** -->
2070
2071<div>
2072<table border="1" cellspacing="0">
Bill Wendlingcf1f6c82012-03-06 09:22:03 +0000[diff] [blame]2073 <col width="200">
2074 <col width="200">
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2075 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2076 <th>TAG</th>
2077 <th>Value</th>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2078 </tr>
2079 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2080 <td>DW_TAG_APPLE_property</td>
2081 <td>0x4200</td>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2082 </tr>
2083</table>
2084
2085</div>
2086
2087<!-- *********************************************************************** -->
2088<h4>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2089 <a name="objcpropertynewattributes">New DWARF Attributes</a>
2090</h4>
2091<!-- *********************************************************************** -->
2092
2093<div>
2094<table border="1" cellspacing="0">
Bill Wendlingcf1f6c82012-03-06 09:22:03 +0000[diff] [blame]2095 <col width="200">
2096 <col width="200">
2097 <col width="200">
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2098 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2099 <th>Attribute</th>
2100 <th>Value</th>
2101 <th>Classes</th>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2102 </tr>
2103 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2104 <td>DW_AT_APPLE_property</td>
2105 <td>0x3fed</td>
2106 <td>Reference</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2107 </tr>
2108 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2109 <td>DW_AT_APPLE_property_getter</td>
2110 <td>0x3fe9</td>
2111 <td>String</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2112 </tr>
2113 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2114 <td>DW_AT_APPLE_property_setter</td>
2115 <td>0x3fea</td>
2116 <td>String</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2117 </tr>
2118 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2119 <td>DW_AT_APPLE_property_attribute</td>
2120 <td>0x3feb</td>
2121 <td>Constant</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2122 </tr>
2123</table>
2124
2125</div>
2126
2127<!-- *********************************************************************** -->
2128<h4>
2129 <a name="objcpropertynewconstants">New DWARF Constants</a>
2130</h4>
2131<!-- *********************************************************************** -->
2132
2133<div>
2134<table border="1" cellspacing="0">
Bill Wendlingcf1f6c82012-03-06 09:22:03 +0000[diff] [blame]2135 <col width="200">
2136 <col width="200">
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2137 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2138 <th>Name</th>
2139 <th>Value</th>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2140 </tr>
2141 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2142 <td>DW_AT_APPLE_PROPERTY_readonly</td>
2143 <td>0x1</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2144 </tr>
2145 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2146 <td>DW_AT_APPLE_PROPERTY_readwrite</td>
2147 <td>0x2</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2148 </tr>
2149 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2150 <td>DW_AT_APPLE_PROPERTY_assign</td>
2151 <td>0x4</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2152 </tr>
2153 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2154 <td>DW_AT_APPLE_PROPERTY_retain</td>
2155 <td>0x8</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2156 </tr>
2157 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2158 <td>DW_AT_APPLE_PROPERTY_copy</td>
2159 <td>0x10</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2160 </tr>
2161 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2162 <td>DW_AT_APPLE_PROPERTY_nonatomic</td>
2163 <td>0x20</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2164 </tr>
2165</table>
2166
2167</div>
2168</div>
2169</div>
2170
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2171<div>
2172<!-- ======================================================================= -->
2173<h3>
2174 <a name="acceltable">Name Accelerator Tables</a>
2175</h3>
2176<!-- ======================================================================= -->
2177<!-- ======================================================================= -->
2178<h4>
Eric Christopher5b7634f2012-03-06 02:25:41 +0000[diff] [blame]2179 <a name="acceltableintroduction">Introduction</a>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2180</h4>
2181<!-- ======================================================================= -->
2182<div>
2183<p>The .debug_pubnames and .debug_pubtypes formats are not what a debugger
2184 needs. The "pub" in the section name indicates that the entries in the
2185 table are publicly visible names only. This means no static or hidden
2186 functions show up in the .debug_pubnames. No static variables or private class
2187 variables are in the .debug_pubtypes. Many compilers add different things to
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2188 these tables, so we can't rely upon the contents between gcc, icc, or clang.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2189
2190<p>The typical query given by users tends not to match up with the contents of
2191 these tables. For example, the DWARF spec states that "In the case of the
2192 name of a function member or static data member of a C++ structure, class or
2193 union, the name presented in the .debug_pubnames section is not the simple
2194 name given by the DW_AT_name attribute of the referenced debugging information
2195 entry, but rather the fully qualified name of the data or function member."
2196 So the only names in these tables for complex C++ entries is a fully
2197 qualified name. Debugger users tend not to enter their search strings as
2198 "a::b::c(int,const Foo&) const", but rather as "c", "b::c" , or "a::b::c". So
2199 the name entered in the name table must be demangled in order to chop it up
2200 appropriately and additional names must be manually entered into the table
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2201 to make it effective as a name lookup table for debuggers to use.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2202
2203<p>All debuggers currently ignore the .debug_pubnames table as a result of
2204 its inconsistent and useless public-only name content making it a waste of
2205 space in the object file. These tables, when they are written to disk, are
2206 not sorted in any way, leaving every debugger to do its own parsing
2207 and sorting. These tables also include an inlined copy of the string values
2208 in the table itself making the tables much larger than they need to be on
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2209 disk, especially for large C++ programs.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2210
2211<p>Can't we just fix the sections by adding all of the names we need to this
2212 table? No, because that is not what the tables are defined to contain and we
2213 won't know the difference between the old bad tables and the new good tables.
2214 At best we could make our own renamed sections that contain all of the data
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2215 we need.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2216
2217<p>These tables are also insufficient for what a debugger like LLDB needs.
2218 LLDB uses clang for its expression parsing where LLDB acts as a PCH. LLDB is
2219 then often asked to look for type "foo" or namespace "bar", or list items in
2220 namespace "baz". Namespaces are not included in the pubnames or pubtypes
2221 tables. Since clang asks a lot of questions when it is parsing an expression,
2222 we need to be very fast when looking up names, as it happens a lot. Having new
2223 accelerator tables that are optimized for very quick lookups will benefit
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2224 this type of debugging experience greatly.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2225
2226<p>We would like to generate name lookup tables that can be mapped into
2227 memory from disk, and used as is, with little or no up-front parsing. We would
2228 also be able to control the exact content of these different tables so they
2229 contain exactly what we need. The Name Accelerator Tables were designed
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2230 to fix these issues. In order to solve these issues we need to:</p>
2231
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2232<ul>
2233 <li>Have a format that can be mapped into memory from disk and used as is</li>
2234 <li>Lookups should be very fast</li>
2235 <li>Extensible table format so these tables can be made by many producers</li>
2236 <li>Contain all of the names needed for typical lookups out of the box</li>
2237 <li>Strict rules for the contents of tables</li>
2238</ul>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2239
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2240<p>Table size is important and the accelerator table format should allow the
2241 reuse of strings from common string tables so the strings for the names are
2242 not duplicated. We also want to make sure the table is ready to be used as-is
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2243 by simply mapping the table into memory with minimal header parsing.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2244
2245<p>The name lookups need to be fast and optimized for the kinds of lookups
2246 that debuggers tend to do. Optimally we would like to touch as few parts of
2247 the mapped table as possible when doing a name lookup and be able to quickly
2248 find the name entry we are looking for, or discover there are no matches. In
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2249 the case of debuggers we optimized for lookups that fail most of the time.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2250
2251<p>Each table that is defined should have strict rules on exactly what is in
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2252 the accelerator tables and documented so clients can rely on the content.</p>
2253
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2254</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2255
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2256<!-- ======================================================================= -->
2257<h4>
2258 <a name="acceltablehashes">Hash Tables</a>
2259</h4>
2260<!-- ======================================================================= -->
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2261
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2262<div>
2263<h5>Standard Hash Tables</h5>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2264
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2265<p>Typical hash tables have a header, buckets, and each bucket points to the
2266bucket contents:
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2267</p>
2268
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2269<div class="doc_code">
2270<pre>
2271.------------.
2272| HEADER |
2273|------------|
2274| BUCKETS |
2275|------------|
2276| DATA |
2277`------------'
2278</pre>
2279</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2280
2281<p>The BUCKETS are an array of offsets to DATA for each hash:</p>
2282
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2283<div class="doc_code">
2284<pre>
2285.------------.
2286| 0x00001000 | BUCKETS[0]
2287| 0x00002000 | BUCKETS[1]
2288| 0x00002200 | BUCKETS[2]
2289| 0x000034f0 | BUCKETS[3]
2290| | ...
2291| 0xXXXXXXXX | BUCKETS[n_buckets]
2292'------------'
2293</pre>
2294</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2295
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2296<p>So for bucket[3] in the example above, we have an offset into the table
2297 0x000034f0 which points to a chain of entries for the bucket. Each bucket
2298 must contain a next pointer, full 32 bit hash value, the string itself,
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2299 and the data for the current string value.</p>
2300
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2301<div class="doc_code">
2302<pre>
2303 .------------.
23040x000034f0: | 0x00003500 | next pointer
2305 | 0x12345678 | 32 bit hash
2306 | "erase" | string value
2307 | data[n] | HashData for this bucket
2308 |------------|
23090x00003500: | 0x00003550 | next pointer
2310 | 0x29273623 | 32 bit hash
2311 | "dump" | string value
2312 | data[n] | HashData for this bucket
2313 |------------|
23140x00003550: | 0x00000000 | next pointer
2315 | 0x82638293 | 32 bit hash
2316 | "main" | string value
2317 | data[n] | HashData for this bucket
2318 `------------'
2319</pre>
2320</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2321
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2322<p>The problem with this layout for debuggers is that we need to optimize for
2323 the negative lookup case where the symbol we're searching for is not present.
2324 So if we were to lookup "printf" in the table above, we would make a 32 hash
2325 for "printf", it might match bucket[3]. We would need to go to the offset
2326 0x000034f0 and start looking to see if our 32 bit hash matches. To do so, we
2327 need to read the next pointer, then read the hash, compare it, and skip to
2328 the next bucket. Each time we are skipping many bytes in memory and touching
2329 new cache pages just to do the compare on the full 32 bit hash. All of these
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2330 accesses then tell us that we didn't have a match.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2331
2332<h5>Name Hash Tables</h5>
2333
2334<p>To solve the issues mentioned above we have structured the hash tables
2335 a bit differently: a header, buckets, an array of all unique 32 bit hash
2336 values, followed by an array of hash value data offsets, one for each hash
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2337 value, then the data for all hash values:</p>
2338
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2339<div class="doc_code">
2340<pre>
2341.-------------.
2342| HEADER |
2343|-------------|
2344| BUCKETS |
2345|-------------|
2346| HASHES |
2347|-------------|
2348| OFFSETS |
2349|-------------|
2350| DATA |
2351`-------------'
2352</pre>
2353</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2354
Eric Christopher5b7634f2012-03-06 02:25:41 +0000[diff] [blame]2355<p>The BUCKETS in the name tables are an index into the HASHES array. By
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2356 making all of the full 32 bit hash values contiguous in memory, we allow
2357 ourselves to efficiently check for a match while touching as little
Eric Christopher5b7634f2012-03-06 02:25:41 +0000[diff] [blame]2358 memory as possible. Most often checking the 32 bit hash values is as far as
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2359 the lookup goes. If it does match, it usually is a match with no collisions.
2360 So for a table with "n_buckets" buckets, and "n_hashes" unique 32 bit hash
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2361 values, we can clarify the contents of the BUCKETS, HASHES and OFFSETS as:</p>
2362
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2363<div class="doc_code">
2364<pre>
2365.-------------------------.
2366| HEADER.magic | uint32_t
2367| HEADER.version | uint16_t
2368| HEADER.hash_function | uint16_t
2369| HEADER.bucket_count | uint32_t
2370| HEADER.hashes_count | uint32_t
2371| HEADER.header_data_len | uint32_t
2372| HEADER_DATA | HeaderData
2373|-------------------------|
2374| BUCKETS | uint32_t[n_buckets] // 32 bit hash indexes
2375|-------------------------|
2376| HASHES | uint32_t[n_buckets] // 32 bit hash values
2377|-------------------------|
2378| OFFSETS | uint32_t[n_buckets] // 32 bit offsets to hash value data
2379|-------------------------|
2380| ALL HASH DATA |
2381`-------------------------'
2382</pre>
2383</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2384
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2385<p>So taking the exact same data from the standard hash example above we end up
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2386 with:</p>
2387
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2388<div class="doc_code">
2389<pre>
2390 .------------.
2391 | HEADER |
2392 |------------|
2393 | 0 | BUCKETS[0]
2394 | 2 | BUCKETS[1]
2395 | 5 | BUCKETS[2]
2396 | 6 | BUCKETS[3]
2397 | | ...
2398 | ... | BUCKETS[n_buckets]
2399 |------------|
2400 | 0x........ | HASHES[0]
2401 | 0x........ | HASHES[1]
2402 | 0x........ | HASHES[2]
2403 | 0x........ | HASHES[3]
2404 | 0x........ | HASHES[4]
2405 | 0x........ | HASHES[5]
2406 | 0x12345678 | HASHES[6] hash for BUCKETS[3]
2407 | 0x29273623 | HASHES[7] hash for BUCKETS[3]
2408 | 0x82638293 | HASHES[8] hash for BUCKETS[3]
2409 | 0x........ | HASHES[9]
2410 | 0x........ | HASHES[10]
2411 | 0x........ | HASHES[11]
2412 | 0x........ | HASHES[12]
2413 | 0x........ | HASHES[13]
2414 | 0x........ | HASHES[n_hashes]
2415 |------------|
2416 | 0x........ | OFFSETS[0]
2417 | 0x........ | OFFSETS[1]
2418 | 0x........ | OFFSETS[2]
2419 | 0x........ | OFFSETS[3]
2420 | 0x........ | OFFSETS[4]
2421 | 0x........ | OFFSETS[5]
2422 | 0x000034f0 | OFFSETS[6] offset for BUCKETS[3]
2423 | 0x00003500 | OFFSETS[7] offset for BUCKETS[3]
2424 | 0x00003550 | OFFSETS[8] offset for BUCKETS[3]
2425 | 0x........ | OFFSETS[9]
2426 | 0x........ | OFFSETS[10]
2427 | 0x........ | OFFSETS[11]
2428 | 0x........ | OFFSETS[12]
2429 | 0x........ | OFFSETS[13]
2430 | 0x........ | OFFSETS[n_hashes]
2431 |------------|
2432 | |
2433 | |
2434 | |
2435 | |
2436 | |
2437 |------------|
24380x000034f0: | 0x00001203 | .debug_str ("erase")
2439 | 0x00000004 | A 32 bit array count - number of HashData with name "erase"
2440 | 0x........ | HashData[0]
2441 | 0x........ | HashData[1]
2442 | 0x........ | HashData[2]
2443 | 0x........ | HashData[3]
2444 | 0x00000000 | String offset into .debug_str (terminate data for hash)
2445 |------------|
24460x00003500: | 0x00001203 | String offset into .debug_str ("collision")
2447 | 0x00000002 | A 32 bit array count - number of HashData with name "collision"
2448 | 0x........ | HashData[0]
2449 | 0x........ | HashData[1]
2450 | 0x00001203 | String offset into .debug_str ("dump")
2451 | 0x00000003 | A 32 bit array count - number of HashData with name "dump"
2452 | 0x........ | HashData[0]
2453 | 0x........ | HashData[1]
2454 | 0x........ | HashData[2]
2455 | 0x00000000 | String offset into .debug_str (terminate data for hash)
2456 |------------|
24570x00003550: | 0x00001203 | String offset into .debug_str ("main")
2458 | 0x00000009 | A 32 bit array count - number of HashData with name "main"
2459 | 0x........ | HashData[0]
2460 | 0x........ | HashData[1]
2461 | 0x........ | HashData[2]
2462 | 0x........ | HashData[3]
2463 | 0x........ | HashData[4]
2464 | 0x........ | HashData[5]
2465 | 0x........ | HashData[6]
2466 | 0x........ | HashData[7]
2467 | 0x........ | HashData[8]
2468 | 0x00000000 | String offset into .debug_str (terminate data for hash)
2469 `------------'
2470</pre>
2471</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2472
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2473<p>So we still have all of the same data, we just organize it more efficiently
2474 for debugger lookup. If we repeat the same "printf" lookup from above, we
2475 would hash "printf" and find it matches BUCKETS[3] by taking the 32 bit hash
2476 value and modulo it by n_buckets. BUCKETS[3] contains "6" which is the index
2477 into the HASHES table. We would then compare any consecutive 32 bit hashes
2478 values in the HASHES array as long as the hashes would be in BUCKETS[3]. We
2479 do this by verifying that each subsequent hash value modulo n_buckets is still
2480 3. In the case of a failed lookup we would access the memory for BUCKETS[3], and
2481 then compare a few consecutive 32 bit hashes before we know that we have no match.
2482 We don't end up marching through multiple words of memory and we really keep the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2483 number of processor data cache lines being accessed as small as possible.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2484
2485<p>The string hash that is used for these lookup tables is the Daniel J.
2486 Bernstein hash which is also used in the ELF GNU_HASH sections. It is a very
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2487 good hash for all kinds of names in programs with very few hash collisions.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2488
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2489<p>Empty buckets are designated by using an invalid hash index of UINT32_MAX.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2490</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2491
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2492<!-- ======================================================================= -->
2493<h4>
2494 <a name="acceltabledetails">Details</a>
2495</h4>
2496<!-- ======================================================================= -->
2497<div>
2498<p>These name hash tables are designed to be generic where specializations of
2499 the table get to define additional data that goes into the header
2500 ("HeaderData"), how the string value is stored ("KeyType") and the content
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2501 of the data for each hash value.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2502
2503<h5>Header Layout</h5>
2504<p>The header has a fixed part, and the specialized part. The exact format of
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2505 the header is:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2506<div class="doc_code">
2507<pre>
2508struct Header
2509{
2510 uint32_t magic; // 'HASH' magic value to allow endian detection
2511 uint16_t version; // Version number
2512 uint16_t hash_function; // The hash function enumeration that was used
2513 uint32_t bucket_count; // The number of buckets in this hash table
2514 uint32_t hashes_count; // The total number of unique hash values and hash data offsets in this table
2515 uint32_t header_data_len; // The bytes to skip to get to the hash indexes (buckets) for correct alignment
2516 // Specifically the length of the following HeaderData field - this does not
2517 // include the size of the preceding fields
2518 HeaderData header_data; // Implementation specific header data
2519};
2520</pre>
2521</div>
2522<p>The header starts with a 32 bit "magic" value which must be 'HASH' encoded as
2523 an ASCII integer. This allows the detection of the start of the hash table and
2524 also allows the table's byte order to be determined so the table can be
2525 correctly extracted. The "magic" value is followed by a 16 bit version number
2526 which allows the table to be revised and modified in the future. The current
2527 version number is 1. "hash_function" is a uint16_t enumeration that specifies
2528 which hash function was used to produce this table. The current values for the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2529 hash function enumerations include:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2530<div class="doc_code">
2531<pre>
2532enum HashFunctionType
2533{
2534 eHashFunctionDJB = 0u, // Daniel J Bernstein hash function
2535};
2536</pre>
2537</div>
2538<p>"bucket_count" is a 32 bit unsigned integer that represents how many buckets
2539 are in the BUCKETS array. "hashes_count" is the number of unique 32 bit hash
2540 values that are in the HASHES array, and is the same number of offsets are
2541 contained in the OFFSETS array. "header_data_len" specifies the size in
2542 bytes of the HeaderData that is filled in by specialized versions of this
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2543 table.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2544
2545<h5>Fixed Lookup</h5>
2546<p>The header is followed by the buckets, hashes, offsets, and hash value
2547 data.
2548<div class="doc_code">
2549<pre>
2550struct FixedTable
2551{
2552 uint32_t buckets[Header.bucket_count]; // An array of hash indexes into the "hashes[]" array below
2553 uint32_t hashes [Header.hashes_count]; // Every unique 32 bit hash for the entire table is in this table
2554 uint32_t offsets[Header.hashes_count]; // An offset that corresponds to each item in the "hashes[]" array above
2555};
2556</pre>
2557</div>
2558<p>"buckets" is an array of 32 bit indexes into the "hashes" array. The
2559 "hashes" array contains all of the 32 bit hash values for all names in the
2560 hash table. Each hash in the "hashes" table has an offset in the "offsets"
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2561 array that points to the data for the hash value.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2562
2563<p>This table setup makes it very easy to repurpose these tables to contain
2564 different data, while keeping the lookup mechanism the same for all tables.
2565 This layout also makes it possible to save the table to disk and map it in
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2566 later and do very efficient name lookups with little or no parsing.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2567
2568<p>DWARF lookup tables can be implemented in a variety of ways and can store
2569 a lot of information for each name. We want to make the DWARF tables
2570 extensible and able to store the data efficiently so we have used some of the
2571 DWARF features that enable efficient data storage to define exactly what kind
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2572 of data we store for each name.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2573
2574<p>The "HeaderData" contains a definition of the contents of each HashData
2575 chunk. We might want to store an offset to all of the debug information
2576 entries (DIEs) for each name. To keep things extensible, we create a list of
2577 items, or Atoms, that are contained in the data for each name. First comes the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2578 type of the data in each atom:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2579<div class="doc_code">
2580<pre>
2581enum AtomType
2582{
2583 eAtomTypeNULL = 0u,
2584 eAtomTypeDIEOffset = 1u, // DIE offset, check form for encoding
2585 eAtomTypeCUOffset = 2u, // DIE offset of the compiler unit header that contains the item in question
2586 eAtomTypeTag = 3u, // DW_TAG_xxx value, should be encoded as DW_FORM_data1 (if no tags exceed 255) or DW_FORM_data2
2587 eAtomTypeNameFlags = 4u, // Flags from enum NameFlags
2588 eAtomTypeTypeFlags = 5u, // Flags from enum TypeFlags
2589};
2590</pre>
2591</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2592<p>The enumeration values and their meanings are:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2593<div class="doc_code">
2594<pre>
2595 eAtomTypeNULL - a termination atom that specifies the end of the atom list
2596 eAtomTypeDIEOffset - an offset into the .debug_info section for the DWARF DIE for this name
2597 eAtomTypeCUOffset - an offset into the .debug_info section for the CU that contains the DIE
2598 eAtomTypeDIETag - The DW_TAG_XXX enumeration value so you don't have to parse the DWARF to see what it is
2599 eAtomTypeNameFlags - Flags for functions and global variables (isFunction, isInlined, isExternal...)
2600 eAtomTypeTypeFlags - Flags for types (isCXXClass, isObjCClass, ...)
2601</pre>
2602</div>
2603<p>Then we allow each atom type to define the atom type and how the data for
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2604 each atom type data is encoded:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2605<div class="doc_code">
2606<pre>
2607struct Atom
2608{
2609 uint16_t type; // AtomType enum value
2610 uint16_t form; // DWARF DW_FORM_XXX defines
2611};
2612</pre>
2613</div>
2614<p>The "form" type above is from the DWARF specification and defines the
2615 exact encoding of the data for the Atom type. See the DWARF specification for
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2616 the DW_FORM_ definitions.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2617<div class="doc_code">
2618<pre>
2619struct HeaderData
2620{
2621 uint32_t die_offset_base;
2622 uint32_t atom_count;
2623 Atoms atoms[atom_count0];
2624};
2625</pre>
2626</div>
2627<p>"HeaderData" defines the base DIE offset that should be added to any atoms
2628 that are encoded using the DW_FORM_ref1, DW_FORM_ref2, DW_FORM_ref4,
2629 DW_FORM_ref8 or DW_FORM_ref_udata. It also defines what is contained in
2630 each "HashData" object -- Atom.form tells us how large each field will be in
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2631 the HashData and the Atom.type tells us how this data should be interpreted.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2632
2633<p>For the current implementations of the ".apple_names" (all functions + globals),
2634 the ".apple_types" (names of all types that are defined), and the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2635 ".apple_namespaces" (all namespaces), we currently set the Atom array to be:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2636<div class="doc_code">
2637<pre>
2638HeaderData.atom_count = 1;
2639HeaderData.atoms[0].type = eAtomTypeDIEOffset;
2640HeaderData.atoms[0].form = DW_FORM_data4;
2641</pre>
2642</div>
2643<p>This defines the contents to be the DIE offset (eAtomTypeDIEOffset) that is
2644 encoded as a 32 bit value (DW_FORM_data4). This allows a single name to have
2645 multiple matching DIEs in a single file, which could come up with an inlined
2646 function for instance. Future tables could include more information about the
2647 DIE such as flags indicating if the DIE is a function, method, block,
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2648 or inlined.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2649
2650<p>The KeyType for the DWARF table is a 32 bit string table offset into the
2651 ".debug_str" table. The ".debug_str" is the string table for the DWARF which
2652 may already contain copies of all of the strings. This helps make sure, with
2653 help from the compiler, that we reuse the strings between all of the DWARF
2654 sections and keeps the hash table size down. Another benefit to having the
2655 compiler generate all strings as DW_FORM_strp in the debug info, is that
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2656 DWARF parsing can be made much faster.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2657
2658<p>After a lookup is made, we get an offset into the hash data. The hash data
2659 needs to be able to deal with 32 bit hash collisions, so the chunk of data
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2660 at the offset in the hash data consists of a triple:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2661<div class="doc_code">
2662<pre>
2663uint32_t str_offset
2664uint32_t hash_data_count
2665HashData[hash_data_count]
2666</pre>
2667</div>
2668<p>If "str_offset" is zero, then the bucket contents are done. 99.9% of the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2669 hash data chunks contain a single item (no 32 bit hash collision):</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2670<div class="doc_code">
2671<pre>
2672.------------.
2673| 0x00001023 | uint32_t KeyType (.debug_str[0x0001023] => "main")
2674| 0x00000004 | uint32_t HashData count
2675| 0x........ | uint32_t HashData[0] DIE offset
2676| 0x........ | uint32_t HashData[1] DIE offset
2677| 0x........ | uint32_t HashData[2] DIE offset
2678| 0x........ | uint32_t HashData[3] DIE offset
2679| 0x00000000 | uint32_t KeyType (end of hash chain)
2680`------------'
2681</pre>
2682</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2683<p>If there are collisions, you will have multiple valid string offsets:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2684<div class="doc_code">
2685<pre>
2686.------------.
2687| 0x00001023 | uint32_t KeyType (.debug_str[0x0001023] => "main")
2688| 0x00000004 | uint32_t HashData count
2689| 0x........ | uint32_t HashData[0] DIE offset
2690| 0x........ | uint32_t HashData[1] DIE offset
2691| 0x........ | uint32_t HashData[2] DIE offset
2692| 0x........ | uint32_t HashData[3] DIE offset
2693| 0x00002023 | uint32_t KeyType (.debug_str[0x0002023] => "print")
2694| 0x00000002 | uint32_t HashData count
2695| 0x........ | uint32_t HashData[0] DIE offset
2696| 0x........ | uint32_t HashData[1] DIE offset
2697| 0x00000000 | uint32_t KeyType (end of hash chain)
2698`------------'
2699</pre>
2700</div>
2701<p>Current testing with real world C++ binaries has shown that there is around 1
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2702 32 bit hash collision per 100,000 name entries.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2703</div>
2704<!-- ======================================================================= -->
2705<h4>
2706 <a name="acceltablecontents">Contents</a>
2707</h4>
2708<!-- ======================================================================= -->
2709<div>
2710<p>As we said, we want to strictly define exactly what is included in the
2711 different tables. For DWARF, we have 3 tables: ".apple_names", ".apple_types",
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2712 and ".apple_namespaces".</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2713
2714<p>".apple_names" sections should contain an entry for each DWARF DIE whose
2715 DW_TAG is a DW_TAG_label, DW_TAG_inlined_subroutine, or DW_TAG_subprogram that
2716 has address attributes: DW_AT_low_pc, DW_AT_high_pc, DW_AT_ranges or
2717 DW_AT_entry_pc. It also contains DW_TAG_variable DIEs that have a DW_OP_addr
2718 in the location (global and static variables). All global and static variables
2719 should be included, including those scoped withing functions and classes. For
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2720 example using the following code:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2721<div class="doc_code">
2722<pre>
2723static int var = 0;
2724
2725void f ()
2726{
2727 static int var = 0;
2728}
2729</pre>
2730</div>
2731<p>Both of the static "var" variables would be included in the table. All
2732 functions should emit both their full names and their basenames. For C or C++,
2733 the full name is the mangled name (if available) which is usually in the
2734 DW_AT_MIPS_linkage_name attribute, and the DW_AT_name contains the function
2735 basename. If global or static variables have a mangled name in a
2736 DW_AT_MIPS_linkage_name attribute, this should be emitted along with the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2737 simple name found in the DW_AT_name attribute.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2738
2739<p>".apple_types" sections should contain an entry for each DWARF DIE whose
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2740 tag is one of:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2741<ul>
2742 <li>DW_TAG_array_type</li>
2743 <li>DW_TAG_class_type</li>
2744 <li>DW_TAG_enumeration_type</li>
2745 <li>DW_TAG_pointer_type</li>
2746 <li>DW_TAG_reference_type</li>
2747 <li>DW_TAG_string_type</li>
2748 <li>DW_TAG_structure_type</li>
2749 <li>DW_TAG_subroutine_type</li>
2750 <li>DW_TAG_typedef</li>
2751 <li>DW_TAG_union_type</li>
2752 <li>DW_TAG_ptr_to_member_type</li>
2753 <li>DW_TAG_set_type</li>
2754 <li>DW_TAG_subrange_type</li>
2755 <li>DW_TAG_base_type</li>
2756 <li>DW_TAG_const_type</li>
2757 <li>DW_TAG_constant</li>
2758 <li>DW_TAG_file_type</li>
2759 <li>DW_TAG_namelist</li>
2760 <li>DW_TAG_packed_type</li>
2761 <li>DW_TAG_volatile_type</li>
2762 <li>DW_TAG_restrict_type</li>
2763 <li>DW_TAG_interface_type</li>
2764 <li>DW_TAG_unspecified_type</li>
2765 <li>DW_TAG_shared_type</li>
2766</ul>
2767<p>Only entries with a DW_AT_name attribute are included, and the entry must
2768 not be a forward declaration (DW_AT_declaration attribute with a non-zero value).
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2769 For example, using the following code:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2770<div class="doc_code">
2771<pre>
2772int main ()
2773{
2774 int *b = 0;
2775 return *b;
2776}
2777</pre>
2778</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2779<p>We get a few type DIEs:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2780<div class="doc_code">
2781<pre>
27820x00000067: TAG_base_type [5]
2783 AT_encoding( DW_ATE_signed )
2784 AT_name( "int" )
2785 AT_byte_size( 0x04 )
2786
27870x0000006e: TAG_pointer_type [6]
2788 AT_type( {0x00000067} ( int ) )
2789 AT_byte_size( 0x08 )
2790</pre>
2791</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2792<p>The DW_TAG_pointer_type is not included because it does not have a DW_AT_name.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2793
2794<p>".apple_namespaces" section should contain all DW_TAG_namespace DIEs. If
2795 we run into a namespace that has no name this is an anonymous namespace,
2796 and the name should be output as "(anonymous namespace)" (without the quotes).
2797 Why? This matches the output of the abi::cxa_demangle() that is in the standard
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2798 C++ library that demangles mangled names.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2799</div>
2800
2801<!-- ======================================================================= -->
2802<h4>
2803 <a name="acceltableextensions">Language Extensions and File Format Changes</a>
2804</h4>
2805<!-- ======================================================================= -->
2806<div>
2807<h5>Objective-C Extensions</h5>
2808<p>".apple_objc" section should contain all DW_TAG_subprogram DIEs for an
2809 Objective-C class. The name used in the hash table is the name of the
2810 Objective-C class itself. If the Objective-C class has a category, then an
2811 entry is made for both the class name without the category, and for the class
2812 name with the category. So if we have a DIE at offset 0x1234 with a name
2813 of method "-[NSString(my_additions) stringWithSpecialString:]", we would add
2814 an entry for "NSString" that points to DIE 0x1234, and an entry for
2815 "NSString(my_additions)" that points to 0x1234. This allows us to quickly
2816 track down all Objective-C methods for an Objective-C class when doing
2817 expressions. It is needed because of the dynamic nature of Objective-C where
2818 anyone can add methods to a class. The DWARF for Objective-C methods is also
2819 emitted differently from C++ classes where the methods are not usually
2820 contained in the class definition, they are scattered about across one or more
2821 compile units. Categories can also be defined in different shared libraries.
2822 So we need to be able to quickly find all of the methods and class functions
2823 given the Objective-C class name, or quickly find all methods and class
2824 functions for a class + category name. This table does not contain any selector
2825 names, it just maps Objective-C class names (or class names + category) to all
2826 of the methods and class functions. The selectors are added as function
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2827 basenames in the .debug_names section.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2828
2829<p>In the ".apple_names" section for Objective-C functions, the full name is the
2830 entire function name with the brackets ("-[NSString stringWithCString:]") and the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2831 basename is the selector only ("stringWithCString:").</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2832
2833<h5>Mach-O Changes</h5>
2834<p>The sections names for the apple hash tables are for non mach-o files. For
2835 mach-o files, the sections should be contained in the "__DWARF" segment with
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2836 names as follows:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2837<ul>
2838 <li>".apple_names" -> "__apple_names"</li>
2839 <li>".apple_types" -> "__apple_types"</li>
2840 <li>".apple_namespaces" -> "__apple_namespac" (16 character limit)</li>
2841 <li> ".apple_objc" -> "__apple_objc"</li>
2842</ul>
2843</div>
2844</div>
2845
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2846<!-- *********************************************************************** -->
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2847
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2848<hr>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2849<address>
2850 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]2851 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2852 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]2853 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2854
2855 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
NAKAMURA Takumib9a33632011-04-09 02:13:37 +0000[diff] [blame]2856 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2857 Last modified: $Date$
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2858</address>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2859
2860</body>
2861</html>