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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
428global variables are collected by named metadata <tt>!llvm.dbg.gv</tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]429
430</div>
431
432<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]433<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]434 <a name="format_subprograms">Subprogram descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]435</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]436
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]437<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]438
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]439<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]440<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]441!2 = metadata !{
442 i32, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
443 ;; (DW_TAG_subprogram)
444 i32, ;; Unused field.
445 metadata, ;; Reference to context descriptor
446 metadata, ;; Name
447 metadata, ;; Display name (fully qualified C++ name)
448 metadata, ;; MIPS linkage name (for C++)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]449 metadata, ;; Reference to file where defined
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]450 i32, ;; Line number where defined
451 metadata, ;; Reference to type descriptor
452 i1, ;; True if the global is local to compile unit (static)
Devang Patel5e06bb82011-04-22 23:10:17 +0000[diff] [blame]453 i1, ;; True if the global is defined in the compile unit (not extern)
454 i32, ;; Virtuality, e.g. dwarf::DW_VIRTUALITY__virtual
455 i32, ;; Index into a virtual function
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]456 metadata, ;; indicates which base type contains the vtable pointer for the
Devang Patel80ecc152010-06-04 22:49:55 +0000[diff] [blame]457 ;; derived class
Devang Patel473f95f2011-12-16 17:50:04 +0000[diff] [blame]458 i32, ;; Flags - Artifical, Private, Protected, Explicit, Prototyped.
Devang Patel5e06bb82011-04-22 23:10:17 +0000[diff] [blame]459 i1, ;; isOptimized
460 Function *,;; Pointer to LLVM function
461 metadata, ;; Lists function template parameters
462 metadata ;; Function declaration descriptor
Devang Patel93d39be2011-08-19 23:28:12 +0000[diff] [blame]463 metadata ;; List of function variables
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]464}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]465</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]466</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]467
468<p>These descriptors provide debug information about functions, methods and
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]469 subprograms. They provide details such as name, return types and the source
Devang Patelda6eed32011-03-29 17:27:08 +0000[diff] [blame]470 location where the subprogram is defined.
Devang Patelda6eed32011-03-29 17:27:08 +0000[diff] [blame]471</p>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]472
473</div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]474
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]475<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]476<h4>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]477 <a name="format_blocks">Block descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]478</h4>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]479
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]480<div>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]481
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]482<div class="doc_code">
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]483<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]484!3 = metadata !{
Devang Patelc79dda22010-10-04 16:51:59 +0000[diff] [blame]485 i32, ;; Tag = 11 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
Devang Patel7f271fc2010-10-01 22:45:00 +0000[diff] [blame]486 metadata,;; Reference to context descriptor
487 i32, ;; Line number
Devang Patel90d81f12011-03-08 16:25:29 +0000[diff] [blame]488 i32, ;; Column number
489 metadata,;; Reference to source file
490 i32 ;; Unique ID to identify blocks from a template function
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]491}
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]492</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]493</div>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]494
Eric Christopher6618a242011-10-11 22:59:11 +0000[diff] [blame]495<p>This descriptor provides debug information about nested blocks within a
Devang Patel7f271fc2010-10-01 22:45:00 +0000[diff] [blame]496 subprogram. The line number and column numbers are used to dinstinguish
497 two lexical blocks at same depth. </p>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]498
Eric Christopher6618a242011-10-11 22:59:11 +0000[diff] [blame]499<div class="doc_code">
500<pre>
501!3 = metadata !{
502 i32, ;; Tag = 11 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
503 metadata ;; Reference to the scope we're annotating with a file change
504 metadata,;; Reference to the file the scope is enclosed in.
505}
506</pre>
507</div>
508
509<p>This descriptor provides a wrapper around a lexical scope to handle file
510 changes in the middle of a lexical block.</p>
511
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]512</div>
513
514<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]515<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]516 <a name="format_basic_type">Basic type descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]517</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]518
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]519<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]520
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]521<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]522<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]523!4 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]524 i32, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]525 ;; (DW_TAG_base_type)
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]526 metadata, ;; Reference to context
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]527 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]528 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]529 i32, ;; Line number where defined (may be 0)
530 i64, ;; Size in bits
531 i64, ;; Alignment in bits
532 i64, ;; Offset in bits
533 i32, ;; Flags
534 i32 ;; DWARF type encoding
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]535}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]536</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]537</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]538
539<p>These descriptors define primitive types used in the code. Example int, bool
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]540 and float. The context provides the scope of the type, which is usually the
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]541 top level. Since basic types are not usually user defined the context
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]542 and line number can be left as NULL and 0. The size, alignment and offset
543 are expressed in bits and can be 64 bit values. The alignment is used to
544 round the offset when embedded in a
545 <a href="#format_composite_type">composite type</a> (example to keep float
546 doubles on 64 bit boundaries.) The offset is the bit offset if embedded in
547 a <a href="#format_composite_type">composite type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]548
549<p>The type encoding provides the details of the type. The values are typically
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]550 one of the following:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]551
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]552<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]553<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]554DW_ATE_address = 1
555DW_ATE_boolean = 2
556DW_ATE_float = 4
557DW_ATE_signed = 5
558DW_ATE_signed_char = 6
559DW_ATE_unsigned = 7
560DW_ATE_unsigned_char = 8
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]561</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]562</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]563
564</div>
565
566<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]567<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]568 <a name="format_derived_type">Derived type descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]569</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]570
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]571<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]572
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]573<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]574<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]575!5 = metadata !{
576 i32, ;; Tag (see below)
577 metadata, ;; Reference to context
578 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]579 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]580 i32, ;; Line number where defined (may be 0)
Devang Patel0ffd10b2010-10-01 19:19:30 +0000[diff] [blame]581 i64, ;; Size in bits
582 i64, ;; Alignment in bits
583 i64, ;; Offset in bits
Eric Christopher402e12a2011-12-16 23:42:33 +0000[diff] [blame]584 i32, ;; Flags to encode attributes, e.g. private
Devang Patele9db5e22011-04-16 00:11:51 +0000[diff] [blame]585 metadata, ;; Reference to type derived from
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]586 metadata, ;; (optional) Name of the Objective C property associated with
587 ;; Objective-C an ivar
Devang Patele9db5e22011-04-16 00:11:51 +0000[diff] [blame]588 metadata, ;; (optional) Name of the Objective C property getter selector.
589 metadata, ;; (optional) Name of the Objective C property setter selector.
590 i32 ;; (optional) Objective C property attributes.
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]591}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]592</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]593</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]594
595<p>These descriptors are used to define types derived from other types. The
596value of the tag varies depending on the meaning. The following are possible
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]597tag values:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]598
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]599<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]600<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]601DW_TAG_formal_parameter = 5
602DW_TAG_member = 13
603DW_TAG_pointer_type = 15
604DW_TAG_reference_type = 16
605DW_TAG_typedef = 22
606DW_TAG_const_type = 38
607DW_TAG_volatile_type = 53
608DW_TAG_restrict_type = 55
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]609</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]610</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]611
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]612<p><tt>DW_TAG_member</tt> is used to define a member of
613 a <a href="#format_composite_type">composite type</a>
614 or <a href="#format_subprograms">subprogram</a>. The type of the member is
615 the <a href="#format_derived_type">derived
616 type</a>. <tt>DW_TAG_formal_parameter</tt> is used to define a member which
617 is a formal argument of a subprogram.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]618
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]619<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]620
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]621<p><tt>DW_TAG_pointer_type</tt>, <tt>DW_TAG_reference_type</tt>,
622 <tt>DW_TAG_const_type</tt>, <tt>DW_TAG_volatile_type</tt> and
Eric Christopheradfc1ef2011-12-16 23:42:35 +0000[diff] [blame]623 <tt>DW_TAG_restrict_type</tt> are used to qualify
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]624 the <a href="#format_derived_type">derived type</a>. </p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]625
626<p><a href="#format_derived_type">Derived type</a> location can be determined
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]627 from the context and line number. The size, alignment and offset are
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]628 expressed in bits and can be 64 bit values. The alignment is used to round
629 the offset when embedded in a <a href="#format_composite_type">composite
630 type</a> (example to keep float doubles on 64 bit boundaries.) The offset is
631 the bit offset if embedded in a <a href="#format_composite_type">composite
632 type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]633
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]634<p>Note that the <tt>void *</tt> type is expressed as a type derived from NULL.
635</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]636
637</div>
638
639<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]640<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]641 <a name="format_composite_type">Composite type descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]642</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]643
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]644<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]645
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]646<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]647<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]648!6 = metadata !{
649 i32, ;; Tag (see below)
650 metadata, ;; Reference to context
651 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]652 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]653 i32, ;; Line number where defined (may be 0)
654 i64, ;; Size in bits
655 i64, ;; Alignment in bits
656 i64, ;; Offset in bits
657 i32, ;; Flags
658 metadata, ;; Reference to type derived from
659 metadata, ;; Reference to array of member descriptors
660 i32 ;; Runtime languages
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]661}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]662</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]663</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]664
665<p>These descriptors are used to define types that are composed of 0 or more
666elements. The value of the tag varies depending on the meaning. The following
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]667are possible tag values:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]668
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]669<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]670<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]671DW_TAG_array_type = 1
672DW_TAG_enumeration_type = 4
673DW_TAG_structure_type = 19
674DW_TAG_union_type = 23
675DW_TAG_vector_type = 259
Bruno Cardoso Lopesd80ddc02009-05-29 17:08:57 +0000[diff] [blame]676DW_TAG_subroutine_type = 21
677DW_TAG_inheritance = 28
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]678</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]679</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]680
Jim Laskeyf8a01a92006-06-15 20:51:43 +0000[diff] [blame]681<p>The vector flag indicates that an array type is a native packed vector.</p>
682
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]683<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]684 (tag = <tt>DW_TAG_vector_type</tt>) are <a href="#format_subrange">subrange
685 descriptors</a>, each representing the range of subscripts at that level of
686 indexing.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]687
688<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]689 <a href="#format_enumeration">enumerator descriptors</a>, each representing
Devang Patelda6eed32011-03-29 17:27:08 +0000[diff] [blame]690 the definition of enumeration value for the set. All enumeration type
691 descriptors are collected by named metadata <tt>!llvm.dbg.enum</tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]692
693<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]694 = <tt>DW_TAG_union_type</tt>) types are any one of
695 the <a href="#format_basic_type">basic</a>,
696 <a href="#format_derived_type">derived</a>
697 or <a href="#format_composite_type">composite</a> type descriptors, each
698 representing a field member of the structure or union.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]699
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]700<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]701 provide information about base classes, static members and member
702 functions. If a member is a <a href="#format_derived_type">derived type
703 descriptor</a> and has a tag of <tt>DW_TAG_inheritance</tt>, then the type
704 represents a base class. If the member of is
705 a <a href="#format_global_variables">global variable descriptor</a> then it
706 represents a static member. And, if the member is
707 a <a href="#format_subprograms">subprogram descriptor</a> then it represents
708 a member function. For static members and member
709 functions, <tt>getName()</tt> returns the members link or the C++ mangled
710 name. <tt>getDisplayName()</tt> the simplied version of the name.</p>
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]711
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]712<p>The first member of subroutine (tag = <tt>DW_TAG_subroutine_type</tt>) type
713 elements is the return type for the subroutine. The remaining elements are
714 the formal arguments to the subroutine.</p>
Jim Laskey094ee722006-06-20 21:13:20 +0000[diff] [blame]715
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]716<p><a href="#format_composite_type">Composite type</a> location can be
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]717 determined from the context and line number. The size, alignment and
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]718 offset are expressed in bits and can be 64 bit values. The alignment is used
719 to round the offset when embedded in
720 a <a href="#format_composite_type">composite type</a> (as an example, to keep
721 float doubles on 64 bit boundaries.) The offset is the bit offset if embedded
722 in a <a href="#format_composite_type">composite type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]723
724</div>
725
726<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]727<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]728 <a name="format_subrange">Subrange descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]729</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]730
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]731<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]732
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]733<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]734<pre>
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]735!42 = metadata !{
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]736 i32, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
737 i64, ;; Low value
738 i64 ;; High value
739}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]740</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]741</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]742
743<p>These descriptors are used to define ranges of array subscripts for an array
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]744 <a href="#format_composite_type">composite type</a>. The low value defines
745 the lower bounds typically zero for C/C++. The high value is the upper
746 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]747 > high the array bounds are not included in generated debugging information.
748</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]749
750</div>
751
752<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]753<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]754 <a name="format_enumeration">Enumerator descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]755</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]756
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]757<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]758
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]759<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]760<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]761!6 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]762 i32, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]763 ;; (DW_TAG_enumerator)
764 metadata, ;; Name
765 i64 ;; Value
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]766}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]767</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]768</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]769
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]770<p>These descriptors are used to define members of an
771 enumeration <a href="#format_composite_type">composite type</a>, it
772 associates the name to the value.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]773
774</div>
775
776<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]777<h4>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]778 <a name="format_variables">Local variables</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]779</h4>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]780
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]781<div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]782
783<div class="doc_code">
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]784<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]785!7 = metadata !{
786 i32, ;; Tag (see below)
787 metadata, ;; Context
788 metadata, ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]789 metadata, ;; Reference to file where defined
Devang Patela83688f2011-03-08 16:29:40 +0000[diff] [blame]790 i32, ;; 24 bit - Line number where defined
791 ;; 8 bit - Argument number. 1 indicates 1st argument.
Devang Patel0a2a3062011-07-27 18:14:50 +0000[diff] [blame]792 metadata, ;; Type descriptor
793 i32, ;; flags
794 metadata ;; (optional) Reference to inline location
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]795}
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]796</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]797</div>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]798
799<p>These descriptors are used to define variables local to a sub program. The
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]800 value of the tag depends on the usage of the variable:</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]801
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]802<div class="doc_code">
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]803<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]804DW_TAG_auto_variable = 256
805DW_TAG_arg_variable = 257
806DW_TAG_return_variable = 258
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]807</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]808</div>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]809
810<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]811 argument variable is any variable that appears as a formal argument to the
812 function. A return variable is used to track the result of a function and
813 has no source correspondent.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]814
Jim Laskey2d395d92006-03-24 09:20:27 +0000[diff] [blame]815<p>The context is either the subprogram or block where the variable is defined.
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]816 Name the source variable name. Context and line indicate where the
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]817 variable was defined. Type descriptor defines the declared type of the
818 variable.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]819
820</div>
821
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]822</div>
823
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]824<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]825<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]826 <a name="format_common_intrinsics">Debugger intrinsic functions</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]827</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]828
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]829<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]830
831<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]832 provide debug information at various points in generated code.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]833
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]834<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]835<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]836 <a name="format_common_declare">llvm.dbg.declare</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]837</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]838
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]839<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]840<pre>
Devang Patel4c7c0c62010-10-01 19:22:16 +0000[diff] [blame]841 void %<a href="#format_common_declare">llvm.dbg.declare</a>(metadata, metadata)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]842</pre>
843
Chad Rosier5bfd9692012-02-18 01:38:41 +0000[diff] [blame]844<p>This intrinsic provides information about a local element (e.g., variable). The
845 first argument is metadata holding the alloca for the variable. The
846 second argument is metadata containing a description of the variable.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]847</div>
848
849<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]850<h4>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]851 <a name="format_common_value">llvm.dbg.value</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]852</h4>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]853
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]854<div>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]855<pre>
Dan Gohman3dfb3cf2010-05-28 17:07:41 +0000[diff] [blame]856 void %<a href="#format_common_value">llvm.dbg.value</a>(metadata, i64, metadata)
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]857</pre>
858
859<p>This intrinsic provides information when a user source variable is set to a
860 new value. The first argument is the new value (wrapped as metadata). The
861 second argument is the offset in the user source variable where the new value
Chad Rosier5bfd9692012-02-18 01:38:41 +0000[diff] [blame]862 is written. The third argument is metadata containing a description of the
863 user source variable.</p>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]864</div>
865
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]866</div>
867
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]868<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]869<h3>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]870 <a name="format_common_lifetime">Object lifetimes and scoping</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]871</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]872
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]873<div>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]874<p>In many languages, the local variables in functions can have their lifetimes
875 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]876 for example, variables are only live (readable and writable) within the
877 source block that they are defined in. In functional languages, values are
878 only readable after they have been defined. Though this is a very obvious
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]879 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]880 scoping in this sense, and does not want to be tied to a language's scoping
881 rules.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]882
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]883<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]884 llvm instructions to encode line number and scoping information. Consider
885 the following C fragment, for example:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]886
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]887<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]888<pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8891. void foo() {
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]8902. int X = 21;
8913. int Y = 22;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8924. {
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]8935. int Z = 23;
8946. Z = X;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8957. }
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]8968. X = Y;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8979. }
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]898</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]899</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]900
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]901<p>Compiled to LLVM, this function would be represented like this:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]902
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]903<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]904<pre>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]905define void @foo() nounwind ssp {
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]906entry:
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]907 %X = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
908 %Y = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
909 %Z = alloca i32, align 4 ; &lt;i32*&gt; [#uses=3]
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000[diff] [blame]910 %0 = bitcast i32* %X to {}* ; &lt;{}*&gt; [#uses=1]
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]911 call void @llvm.dbg.declare(metadata !{i32 * %X}, metadata !0), !dbg !7
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]912 store i32 21, i32* %X, !dbg !8
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000[diff] [blame]913 %1 = bitcast i32* %Y to {}* ; &lt;{}*&gt; [#uses=1]
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]914 call void @llvm.dbg.declare(metadata !{i32 * %Y}, metadata !9), !dbg !10
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]915 store i32 22, i32* %Y, !dbg !11
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000[diff] [blame]916 %2 = bitcast i32* %Z to {}* ; &lt;{}*&gt; [#uses=1]
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]917 call void @llvm.dbg.declare(metadata !{i32 * %Z}, metadata !12), !dbg !14
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]918 store i32 23, i32* %Z, !dbg !15
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]919 %tmp = load i32* %X, !dbg !16 ; &lt;i32&gt; [#uses=1]
920 %tmp1 = load i32* %Y, !dbg !16 ; &lt;i32&gt; [#uses=1]
921 %add = add nsw i32 %tmp, %tmp1, !dbg !16 ; &lt;i32&gt; [#uses=1]
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]922 store i32 %add, i32* %Z, !dbg !16
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]923 %tmp2 = load i32* %Y, !dbg !17 ; &lt;i32&gt; [#uses=1]
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]924 store i32 %tmp2, i32* %X, !dbg !17
925 ret void, !dbg !18
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]926}
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]927
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]928declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]929
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]930!0 = metadata !{i32 459008, metadata !1, metadata !"X",
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]931 metadata !3, i32 2, metadata !6}; [ DW_TAG_auto_variable ]
932!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]933!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo", metadata !"foo",
934 metadata !"foo", metadata !3, i32 1, metadata !4,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]935 i1 false, i1 true}; [DW_TAG_subprogram ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]936!3 = metadata !{i32 458769, i32 0, i32 12, metadata !"foo.c",
937 metadata !"/private/tmp", metadata !"clang 1.1", i1 true,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]938 i1 false, metadata !"", i32 0}; [DW_TAG_compile_unit ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]939!4 = metadata !{i32 458773, metadata !3, metadata !"", null, i32 0, i64 0, i64 0,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]940 i64 0, i32 0, null, metadata !5, i32 0}; [DW_TAG_subroutine_type ]
941!5 = metadata !{null}
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]942!6 = metadata !{i32 458788, metadata !3, metadata !"int", metadata !3, i32 0,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]943 i64 32, i64 32, i64 0, i32 0, i32 5}; [DW_TAG_base_type ]
944!7 = metadata !{i32 2, i32 7, metadata !1, null}
945!8 = metadata !{i32 2, i32 3, metadata !1, null}
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]946!9 = metadata !{i32 459008, metadata !1, metadata !"Y", metadata !3, i32 3,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]947 metadata !6}; [ DW_TAG_auto_variable ]
948!10 = metadata !{i32 3, i32 7, metadata !1, null}
949!11 = metadata !{i32 3, i32 3, metadata !1, null}
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]950!12 = metadata !{i32 459008, metadata !13, metadata !"Z", metadata !3, i32 5,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]951 metadata !6}; [ DW_TAG_auto_variable ]
952!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
953!14 = metadata !{i32 5, i32 9, metadata !13, null}
954!15 = metadata !{i32 5, i32 5, metadata !13, null}
955!16 = metadata !{i32 6, i32 5, metadata !13, null}
956!17 = metadata !{i32 8, i32 3, metadata !1, null}
957!18 = metadata !{i32 9, i32 1, metadata !2, null}
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]958</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]959</div>
960
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]961<p>This example illustrates a few important details about LLVM debugging
962 information. In particular, it shows how the <tt>llvm.dbg.declare</tt>
963 intrinsic and location information, which are attached to an instruction,
964 are applied together to allow a debugger to analyze the relationship between
965 statements, variable definitions, and the code used to implement the
966 function.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]967
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]968<div class="doc_code">
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]969<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]970call void @llvm.dbg.declare(metadata, metadata !0), !dbg !7
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]971</pre>
972</div>
973
974<p>The first intrinsic
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]975 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]976 encodes debugging information for the variable <tt>X</tt>. The metadata
977 <tt>!dbg !7</tt> attached to the intrinsic provides scope information for the
978 variable <tt>X</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]979
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]980<div class="doc_code">
981<pre>
982!7 = metadata !{i32 2, i32 7, metadata !1, null}
983!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]984!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo",
985 metadata !"foo", metadata !"foo", metadata !3, i32 1,
986 metadata !4, i1 false, i1 true}; [DW_TAG_subprogram ]
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]987</pre>
988</div>
989
990<p>Here <tt>!7</tt> is metadata providing location information. It has four
991 fields: line number, column number, scope, and original scope. The original
992 scope represents inline location if this instruction is inlined inside a
993 caller, and is null otherwise. In this example, scope is encoded by
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]994 <tt>!1</tt>. <tt>!1</tt> represents a lexical block inside the scope
995 <tt>!2</tt>, where <tt>!2</tt> is a
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]996 <a href="#format_subprograms">subprogram descriptor</a>. This way the
997 location information attached to the intrinsics indicates that the
998 variable <tt>X</tt> is declared at line number 2 at a function level scope in
999 function <tt>foo</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1000
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]1001<p>Now lets take another example.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1002
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1003<div class="doc_code">
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]1004<pre>
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]1005call void @llvm.dbg.declare(metadata, metadata !12), !dbg !14
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1006</pre>
1007</div>
1008
1009<p>The second intrinsic
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]1010 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1011 encodes debugging information for variable <tt>Z</tt>. The metadata
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1012 <tt>!dbg !14</tt> attached to the intrinsic provides scope information for
1013 the variable <tt>Z</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1014
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1015<div class="doc_code">
1016<pre>
1017!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
1018!14 = metadata !{i32 5, i32 9, metadata !13, null}
1019</pre>
1020</div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1021
John Criswellb34500f2010-03-17 15:01:50 +0000[diff] [blame]1022<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]1023 column number 9 inside of lexical scope <tt>!13</tt>. The lexical scope
1024 itself resides inside of lexical scope <tt>!1</tt> described above.</p>
1025
1026<p>The scope information attached with each instruction provides a
1027 straightforward way to find instructions covered by a scope.</p>
1028
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1029</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1030
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1031</div>
1032
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1033<!-- *********************************************************************** -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1034<h2>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1035 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1036</h2>
Misha Brukman94218a72004-12-09 20:27:37 +0000[diff] [blame]1037<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1038
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1039<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1040
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1041<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]1042 that is effectively identical
1043 to <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3.0</a> in
1044 terms of information content. This allows code generators to trivially
1045 support native debuggers by generating standard dwarf information, and
1046 contains enough information for non-dwarf targets to translate it as
1047 needed.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1048
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1049<p>This section describes the forms used to represent C and C++ programs. Other
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1050 languages could pattern themselves after this (which itself is tuned to
1051 representing programs in the same way that DWARF 3 does), or they could
1052 choose to provide completely different forms if they don't fit into the DWARF
1053 model. As support for debugging information gets added to the various LLVM
1054 source-language front-ends, the information used should be documented
1055 here.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1056
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1057<p>The following sections provide examples of various C/C++ constructs and the
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1058 debug information that would best describe those constructs.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1059
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1060<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1061<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1062 <a name="ccxx_compile_units">C/C++ source file information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1063</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1064
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1065<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1066
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1067<p>Given the source files <tt>MySource.cpp</tt> and <tt>MyHeader.h</tt> located
1068 in the directory <tt>/Users/mine/sources</tt>, the following code:</p>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1069
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1070<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1071<pre>
1072#include "MyHeader.h"
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1073
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1074int main(int argc, char *argv[]) {
1075 return 0;
1076}
1077</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1078</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1079
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1080<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1081
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1082<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1083<pre>
1084...
1085;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1086;; Define the compile unit for the main source file "/Users/mine/sources/MySource.cpp".
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1087;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1088!2 = metadata !{
1089 i32 524305, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1090 i32 0, ;; Unused
1091 i32 4, ;; Language Id
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1092 metadata !"MySource.cpp",
1093 metadata !"/Users/mine/sources",
1094 metadata !"4.2.1 (Based on Apple Inc. build 5649) (LLVM build 00)",
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1095 i1 true, ;; Main Compile Unit
1096 i1 false, ;; Optimized compile unit
1097 metadata !"", ;; Compiler flags
1098 i32 0} ;; Runtime version
1099
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1100;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1101;; Define the file for the file "/Users/mine/sources/MySource.cpp".
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1102;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1103!1 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1104 i32 524329, ;; Tag
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1105 metadata !"MySource.cpp",
1106 metadata !"/Users/mine/sources",
Devang Patel9fea9c22010-07-13 16:53:20 +0000[diff] [blame]1107 metadata !2 ;; Compile unit
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1108}
1109
1110;;
1111;; Define the file for the file "/Users/mine/sources/Myheader.h"
1112;;
1113!3 = metadata !{
1114 i32 524329, ;; Tag
1115 metadata !"Myheader.h"
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1116 metadata !"/Users/mine/sources",
Devang Patel9fea9c22010-07-13 16:53:20 +0000[diff] [blame]1117 metadata !2 ;; Compile unit
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1118}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1119
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1120...
1121</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1122</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1123
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1124<p>llvm::Instruction provides easy access to metadata attached with an
Devang Pateld98ec5f2010-03-26 19:08:36 +0000[diff] [blame]1125instruction. One can extract line number information encoded in LLVM IR
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1126using <tt>Instruction::getMetadata()</tt> and
Devang Pateld98ec5f2010-03-26 19:08:36 +0000[diff] [blame]1127<tt>DILocation::getLineNumber()</tt>.
1128<pre>
1129 if (MDNode *N = I->getMetadata("dbg")) { // Here I is an LLVM instruction
1130 DILocation Loc(N); // DILocation is in DebugInfo.h
1131 unsigned Line = Loc.getLineNumber();
1132 StringRef File = Loc.getFilename();
1133 StringRef Dir = Loc.getDirectory();
1134 }
1135</pre>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1136</div>
1137
1138<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1139<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1140 <a name="ccxx_global_variable">C/C++ global variable information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1141</h3>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1142
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1143<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1144
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1145<p>Given an integer global variable declared as follows:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1146
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1147<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1148<pre>
1149int MyGlobal = 100;
1150</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1151</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1152
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1153<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1154
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1155<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1156<pre>
1157;;
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1158;; Define the global itself.
1159;;
1160%MyGlobal = global int 100
1161...
1162;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1163;; List of debug info of globals
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1164;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1165!llvm.dbg.gv = !{!0}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1166
1167;;
1168;; Define the global variable descriptor. Note the reference to the global
1169;; variable anchor and the global variable itself.
1170;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1171!0 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1172 i32 524340, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1173 i32 0, ;; Unused
1174 metadata !1, ;; Context
1175 metadata !"MyGlobal", ;; Name
1176 metadata !"MyGlobal", ;; Display Name
1177 metadata !"MyGlobal", ;; Linkage Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1178 metadata !3, ;; Compile Unit
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1179 i32 1, ;; Line Number
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1180 metadata !4, ;; Type
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1181 i1 false, ;; Is a local variable
1182 i1 true, ;; Is this a definition
1183 i32* @MyGlobal ;; The global variable
1184}
1185
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1186;;
1187;; Define the basic type of 32 bit signed integer. Note that since int is an
1188;; intrinsic type the source file is NULL and line 0.
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1189;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1190!4 = metadata !{
1191 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1192 metadata !1, ;; Context
1193 metadata !"int", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1194 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1195 i32 0, ;; Line number
1196 i64 32, ;; Size in Bits
1197 i64 32, ;; Align in Bits
1198 i64 0, ;; Offset in Bits
1199 i32 0, ;; Flags
1200 i32 5 ;; Encoding
1201}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1202
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1203</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1204</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1205
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1206</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1207
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1208<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1209<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1210 <a name="ccxx_subprogram">C/C++ function information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1211</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1212
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1213<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1214
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1215<p>Given a function declared as follows:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1216
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1217<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1218<pre>
1219int main(int argc, char *argv[]) {
1220 return 0;
1221}
1222</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1223</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1224
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1225<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1226
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1227<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1228<pre>
1229;;
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1230;; Define the anchor for subprograms. Note that the second field of the
1231;; anchor is 46, which is the same as the tag for subprograms
1232;; (46 = DW_TAG_subprogram.)
1233;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1234!6 = metadata !{
1235 i32 524334, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1236 i32 0, ;; Unused
1237 metadata !1, ;; Context
1238 metadata !"main", ;; Name
1239 metadata !"main", ;; Display name
1240 metadata !"main", ;; Linkage name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1241 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1242 i32 1, ;; Line number
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1243 metadata !4, ;; Type
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1244 i1 false, ;; Is local
Devang Patelda194752011-04-05 22:52:06 +0000[diff] [blame]1245 i1 true, ;; Is definition
1246 i32 0, ;; Virtuality attribute, e.g. pure virtual function
1247 i32 0, ;; Index into virtual table for C++ methods
1248 i32 0, ;; Type that holds virtual table.
1249 i32 0, ;; Flags
1250 i1 false, ;; True if this function is optimized
1251 Function *, ;; Pointer to llvm::Function
1252 null ;; Function template parameters
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1253}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1254;;
1255;; Define the subprogram itself.
1256;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1257define i32 @main(i32 %argc, i8** %argv) {
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1258...
1259}
1260</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1261</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1262
1263</div>
1264
1265<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1266<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1267 <a name="ccxx_basic_types">C/C++ basic types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1268</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1269
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1270<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1271
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1272<p>The following are the basic type descriptors for C/C++ core types:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1273
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1274<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1275<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1276 <a name="ccxx_basic_type_bool">bool</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1277</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1278
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1279<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1280
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1281<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1282<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1283!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1284 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1285 metadata !1, ;; Context
1286 metadata !"bool", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1287 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1288 i32 0, ;; Line number
1289 i64 8, ;; Size in Bits
1290 i64 8, ;; Align in Bits
1291 i64 0, ;; Offset in Bits
1292 i32 0, ;; Flags
1293 i32 2 ;; Encoding
1294}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1295</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1296</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1297
1298</div>
1299
1300<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1301<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1302 <a name="ccxx_basic_char">char</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1303</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1304
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1305<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1306
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1307<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1308<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1309!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1310 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1311 metadata !1, ;; Context
1312 metadata !"char", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1313 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1314 i32 0, ;; Line number
1315 i64 8, ;; Size in Bits
1316 i64 8, ;; Align in Bits
1317 i64 0, ;; Offset in Bits
1318 i32 0, ;; Flags
1319 i32 6 ;; Encoding
1320}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1321</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1322</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1323
1324</div>
1325
1326<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1327<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1328 <a name="ccxx_basic_unsigned_char">unsigned char</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1329</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1330
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1331<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1332
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1333<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1334<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1335!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1336 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1337 metadata !1, ;; Context
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1338 metadata !"unsigned char",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1339 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1340 i32 0, ;; Line number
1341 i64 8, ;; Size in Bits
1342 i64 8, ;; Align in Bits
1343 i64 0, ;; Offset in Bits
1344 i32 0, ;; Flags
1345 i32 8 ;; Encoding
1346}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1347</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1348</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1349
1350</div>
1351
1352<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1353<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1354 <a name="ccxx_basic_short">short</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1355</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1356
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1357<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1358
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1359<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1360<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1361!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1362 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1363 metadata !1, ;; Context
1364 metadata !"short int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1365 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1366 i32 0, ;; Line number
1367 i64 16, ;; Size in Bits
1368 i64 16, ;; Align in Bits
1369 i64 0, ;; Offset in Bits
1370 i32 0, ;; Flags
1371 i32 5 ;; Encoding
1372}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1373</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1374</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1375
1376</div>
1377
1378<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1379<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1380 <a name="ccxx_basic_unsigned_short">unsigned short</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1381</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1382
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1383<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1384
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1385<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1386<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1387!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1388 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1389 metadata !1, ;; Context
1390 metadata !"short unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1391 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1392 i32 0, ;; Line number
1393 i64 16, ;; Size in Bits
1394 i64 16, ;; Align in Bits
1395 i64 0, ;; Offset in Bits
1396 i32 0, ;; Flags
1397 i32 7 ;; Encoding
1398}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1399</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1400</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1401
1402</div>
1403
1404<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1405<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1406 <a name="ccxx_basic_int">int</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1407</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1408
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1409<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1410
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1411<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1412<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1413!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1414 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1415 metadata !1, ;; Context
1416 metadata !"int", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1417 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1418 i32 0, ;; Line number
1419 i64 32, ;; Size in Bits
1420 i64 32, ;; Align in Bits
1421 i64 0, ;; Offset in Bits
1422 i32 0, ;; Flags
1423 i32 5 ;; Encoding
1424}
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1425</pre></div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1426
1427</div>
1428
1429<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1430<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1431 <a name="ccxx_basic_unsigned_int">unsigned int</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1432</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1433
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1434<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1435
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1436<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1437<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1438!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1439 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1440 metadata !1, ;; Context
1441 metadata !"unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1442 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1443 i32 0, ;; Line number
1444 i64 32, ;; Size in Bits
1445 i64 32, ;; Align in Bits
1446 i64 0, ;; Offset in Bits
1447 i32 0, ;; Flags
1448 i32 7 ;; Encoding
1449}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1450</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1451</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1452
1453</div>
1454
1455<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1456<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1457 <a name="ccxx_basic_long_long">long long</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1458</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1459
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1460<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1461
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1462<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1463<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1464!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1465 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1466 metadata !1, ;; Context
1467 metadata !"long long int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1468 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1469 i32 0, ;; Line number
1470 i64 64, ;; Size in Bits
1471 i64 64, ;; Align in Bits
1472 i64 0, ;; Offset in Bits
1473 i32 0, ;; Flags
1474 i32 5 ;; Encoding
1475}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1476</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1477</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1478
1479</div>
1480
1481<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1482<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1483 <a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1484</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1485
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1486<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1487
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1488<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1489<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1490!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1491 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1492 metadata !1, ;; Context
1493 metadata !"long long unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1494 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1495 i32 0, ;; Line number
1496 i64 64, ;; Size in Bits
1497 i64 64, ;; Align in Bits
1498 i64 0, ;; Offset in Bits
1499 i32 0, ;; Flags
1500 i32 7 ;; Encoding
1501}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1502</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1503</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1504
1505</div>
1506
1507<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1508<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1509 <a name="ccxx_basic_float">float</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1510</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1511
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1512<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1513
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1514<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1515<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1516!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1517 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1518 metadata !1, ;; Context
1519 metadata !"float",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1520 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1521 i32 0, ;; Line number
1522 i64 32, ;; Size in Bits
1523 i64 32, ;; Align in Bits
1524 i64 0, ;; Offset in Bits
1525 i32 0, ;; Flags
1526 i32 4 ;; Encoding
1527}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1528</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1529</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1530
1531</div>
1532
1533<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1534<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1535 <a name="ccxx_basic_double">double</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1536</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1537
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1538<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1539
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1540<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1541<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1542!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1543 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1544 metadata !1, ;; Context
1545 metadata !"double",;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1546 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1547 i32 0, ;; Line number
1548 i64 64, ;; Size in Bits
1549 i64 64, ;; Align in Bits
1550 i64 0, ;; Offset in Bits
1551 i32 0, ;; Flags
1552 i32 4 ;; Encoding
1553}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1554</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1555</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1556
1557</div>
1558
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1559</div>
1560
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1561<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1562<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1563 <a name="ccxx_derived_types">C/C++ derived types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1564</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1565
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1566<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1567
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1568<p>Given the following as an example of C/C++ derived type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1569
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1570<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1571<pre>
1572typedef const int *IntPtr;
1573</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1574</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1575
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1576<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1577
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1578<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1579<pre>
1580;;
1581;; Define the typedef "IntPtr".
1582;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1583!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1584 i32 524310, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1585 metadata !1, ;; Context
1586 metadata !"IntPtr", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1587 metadata !3, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1588 i32 0, ;; Line number
1589 i64 0, ;; Size in bits
1590 i64 0, ;; Align in bits
1591 i64 0, ;; Offset in bits
1592 i32 0, ;; Flags
1593 metadata !4 ;; Derived From type
1594}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1595
1596;;
1597;; Define the pointer type.
1598;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1599!4 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1600 i32 524303, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1601 metadata !1, ;; Context
1602 metadata !"", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1603 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1604 i32 0, ;; Line number
1605 i64 64, ;; Size in bits
1606 i64 64, ;; Align in bits
1607 i64 0, ;; Offset in bits
1608 i32 0, ;; Flags
1609 metadata !5 ;; Derived From type
1610}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1611;;
1612;; Define the const type.
1613;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1614!5 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1615 i32 524326, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1616 metadata !1, ;; Context
1617 metadata !"", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1618 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1619 i32 0, ;; Line number
1620 i64 32, ;; Size in bits
1621 i64 32, ;; Align in bits
1622 i64 0, ;; Offset in bits
1623 i32 0, ;; Flags
1624 metadata !6 ;; Derived From type
1625}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1626;;
1627;; Define the int type.
1628;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1629!6 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1630 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1631 metadata !1, ;; Context
1632 metadata !"int", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1633 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1634 i32 0, ;; Line number
1635 i64 32, ;; Size in bits
1636 i64 32, ;; Align in bits
1637 i64 0, ;; Offset in bits
1638 i32 0, ;; Flags
1639 5 ;; Encoding
1640}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1641</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1642</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1643
1644</div>
1645
1646<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1647<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1648 <a name="ccxx_composite_types">C/C++ struct/union types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1649</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1650
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1651<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1652
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1653<p>Given the following as an example of C/C++ struct type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1654
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1655<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1656<pre>
1657struct Color {
1658 unsigned Red;
1659 unsigned Green;
1660 unsigned Blue;
1661};
1662</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1663</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1664
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1665<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1666
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1667<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1668<pre>
1669;;
1670;; Define basic type for unsigned int.
1671;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1672!5 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1673 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1674 metadata !1, ;; Context
1675 metadata !"unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1676 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1677 i32 0, ;; Line number
1678 i64 32, ;; Size in Bits
1679 i64 32, ;; Align in Bits
1680 i64 0, ;; Offset in Bits
1681 i32 0, ;; Flags
1682 i32 7 ;; Encoding
1683}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1684;;
1685;; Define composite type for struct Color.
1686;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1687!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1688 i32 524307, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1689 metadata !1, ;; Context
1690 metadata !"Color", ;; Name
1691 metadata !1, ;; Compile unit
1692 i32 1, ;; Line number
1693 i64 96, ;; Size in bits
1694 i64 32, ;; Align in bits
1695 i64 0, ;; Offset in bits
1696 i32 0, ;; Flags
1697 null, ;; Derived From
1698 metadata !3, ;; Elements
1699 i32 0 ;; Runtime Language
1700}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1701
1702;;
1703;; Define the Red field.
1704;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1705!4 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1706 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1707 metadata !1, ;; Context
1708 metadata !"Red", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1709 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1710 i32 2, ;; Line number
1711 i64 32, ;; Size in bits
1712 i64 32, ;; Align in bits
1713 i64 0, ;; Offset in bits
1714 i32 0, ;; Flags
1715 metadata !5 ;; Derived From type
1716}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1717
1718;;
1719;; Define the Green field.
1720;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1721!6 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1722 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1723 metadata !1, ;; Context
1724 metadata !"Green", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1725 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1726 i32 3, ;; Line number
1727 i64 32, ;; Size in bits
1728 i64 32, ;; Align in bits
1729 i64 32, ;; Offset in bits
1730 i32 0, ;; Flags
1731 metadata !5 ;; Derived From type
1732}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1733
1734;;
1735;; Define the Blue field.
1736;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1737!7 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1738 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1739 metadata !1, ;; Context
1740 metadata !"Blue", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1741 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1742 i32 4, ;; Line number
1743 i64 32, ;; Size in bits
1744 i64 32, ;; Align in bits
1745 i64 64, ;; Offset in bits
1746 i32 0, ;; Flags
1747 metadata !5 ;; Derived From type
1748}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1749
1750;;
1751;; Define the array of fields used by the composite type Color.
1752;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1753!3 = metadata !{metadata !4, metadata !6, metadata !7}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1754</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1755</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1756
1757</div>
1758
1759<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1760<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1761 <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1762</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1763
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1764<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1765
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1766<p>Given the following as an example of C/C++ enumeration type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1767
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1768<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1769<pre>
1770enum Trees {
1771 Spruce = 100,
1772 Oak = 200,
1773 Maple = 300
1774};
1775</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1776</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1777
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1778<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1779
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1780<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1781<pre>
1782;;
1783;; Define composite type for enum Trees
1784;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1785!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1786 i32 524292, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1787 metadata !1, ;; Context
1788 metadata !"Trees", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1789 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1790 i32 1, ;; Line number
1791 i64 32, ;; Size in bits
1792 i64 32, ;; Align in bits
1793 i64 0, ;; Offset in bits
1794 i32 0, ;; Flags
1795 null, ;; Derived From type
1796 metadata !3, ;; Elements
1797 i32 0 ;; Runtime language
1798}
Devang Patel2a610c72009-08-25 05:24:07 +0000[diff] [blame]1799
Devang Patel82459882009-08-26 05:01:18 +0000[diff] [blame]1800;;
1801;; Define the array of enumerators used by composite type Trees.
1802;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1803!3 = metadata !{metadata !4, metadata !5, metadata !6}
1804
1805;;
1806;; Define Spruce enumerator.
1807;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1808!4 = metadata !{i32 524328, metadata !"Spruce", i64 100}
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1809
1810;;
1811;; Define Oak enumerator.
1812;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1813!5 = metadata !{i32 524328, metadata !"Oak", i64 200}
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1814
1815;;
1816;; Define Maple enumerator.
1817;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1818!6 = metadata !{i32 524328, metadata !"Maple", i64 300}
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1819
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1820</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1821</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1822
1823</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1824
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1825</div>
1826
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1827
1828<!-- *********************************************************************** -->
1829<h2>
1830 <a name="llvmdwarfextension">Debugging information format</a>
1831</h2>
1832<!-- *********************************************************************** -->
1833<div>
1834<!-- ======================================================================= -->
1835<h3>
Bill Wendling0eb59142012-03-06 09:17:39 +0000[diff] [blame]1836 <a name="objcproperty">Debugging Information Extension for Objective C Properties</a>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1837</h3>
1838<div>
1839<!-- *********************************************************************** -->
1840<h4>
1841 <a name="objcpropertyintroduction">Introduction</a>
1842</h4>
1843<!-- *********************************************************************** -->
1844
1845<div>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1846<p>Objective C provides a simpler way to declare and define accessor methods
1847using declared properties. The language provides features to declare a
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1848property and to let compiler synthesize accessor methods.
1849</p>
1850
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1851<p>The debugger lets developer inspect Objective C interfaces and their
1852instance variables and class variables. However, the debugger does not know
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1853anything about the properties defined in Objective C interfaces. The debugger
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1854consumes information generated by compiler in DWARF format. The format does
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1855not support encoding of Objective C properties. This proposal describes DWARF
1856extensions to encode Objective C properties, which the debugger can use to let
1857developers inspect Objective C properties.
1858</p>
1859
1860</div>
1861
1862
1863<!-- *********************************************************************** -->
1864<h4>
1865 <a name="objcpropertyproposal">Proposal</a>
1866</h4>
1867<!-- *********************************************************************** -->
1868
1869<div>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1870<p>Objective C properties exist separately from class members. A property
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1871can be defined only by &quot;setter&quot; and &quot;getter&quot; selectors, and
1872be calculated anew on each access. Or a property can just be a direct access
1873to some declared ivar. Finally it can have an ivar &quot;automatically
1874synthesized&quot; for it by the compiler, in which case the property can be
1875referred to in user code directly using the standard C dereference syntax as
1876well as through the property &quot;dot&quot; syntax, but there is no entry in
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1877the @interface declaration corresponding to this ivar.
1878</p>
1879<p>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1880To facilitate debugging, these properties we will add a new DWARF TAG into the
1881DW_TAG_structure_type definition for the class to hold the description of a
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1882given property, and a set of DWARF attributes that provide said description.
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1883The property tag will also contain the name and declared type of the property.
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1884</p>
1885<p>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1886If there is a related ivar, there will also be a DWARF property attribute placed
1887in the DW_TAG_member DIE for that ivar referring back to the property TAG for
1888that property. And in the case where the compiler synthesizes the ivar directly,
1889the compiler is expected to generate a DW_TAG_member for that ivar (with the
1890DW_AT_artificial set to 1), whose name will be the name used to access this
1891ivar directly in code, and with the property attribute pointing back to the
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1892property it is backing.
1893</p>
1894<p>
1895The following examples will serve as illustration for our discussion:
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1896</p>
1897
1898<div class="doc_code">
1899<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1900@interface I1 {
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1901 int n2;
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1902}
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1903
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1904@property int p1;
1905@property int p2;
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1906@end
1907
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1908@implementation I1
1909@synthesize p1;
1910@synthesize p2 = n2;
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1911@end
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1912</pre>
1913</div>
1914
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1915<p>
1916This produces the following DWARF (this is a &quot;pseudo dwarfdump&quot; output):
1917</p>
1918<div class="doc_code">
1919<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]19200x00000100: TAG_structure_type [7] *
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1921 AT_APPLE_runtime_class( 0x10 )
1922 AT_name( "I1" )
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1923 AT_decl_file( "Objc_Property.m" )
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1924 AT_decl_line( 3 )
1925
19260x00000110 TAG_APPLE_property
1927 AT_name ( "p1" )
1928 AT_type ( {0x00000150} ( int ) )
1929
19300x00000120: TAG_APPLE_property
1931 AT_name ( "p2" )
1932 AT_type ( {0x00000150} ( int ) )
1933
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]19340x00000130: TAG_member [8]
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1935 AT_name( "_p1" )
1936 AT_APPLE_property ( {0x00000110} "p1" )
1937 AT_type( {0x00000150} ( int ) )
1938 AT_artificial ( 0x1 )
1939
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]19400x00000140: TAG_member [8]
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1941 AT_name( "n2" )
1942 AT_APPLE_property ( {0x00000120} "p2" )
1943 AT_type( {0x00000150} ( int ) )
1944
19450x00000150: AT_type( ( int ) )
1946</pre>
1947</div>
1948
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1949<p> Note, the current convention is that the name of the ivar for an
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1950auto-synthesized property is the name of the property from which it derives with
1951an underscore prepended, as is shown in the example.
1952But we actually don't need to know this convention, since we are given the name
1953of the ivar directly.
1954</p>
1955
1956<p>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1957Also, it is common practice in ObjC to have different property declarations in
1958the @interface and @implementation - e.g. to provide a read-only property in
1959the interface,and a read-write interface in the implementation. In that case,
1960the compiler should emit whichever property declaration will be in force in the
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1961current translation unit.
1962</p>
1963
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1964<p> Developers can decorate a property with attributes which are encoded using
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1965DW_AT_APPLE_property_attribute.
1966</p>
1967
1968<div class="doc_code">
1969<pre>
1970@property (readonly, nonatomic) int pr;
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1971</pre>
1972</div>
1973<p>
1974Which produces a property tag:
1975<p>
1976<div class="doc_code">
1977<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1978TAG_APPLE_property [8]
1979 AT_name( "pr" )
1980 AT_type ( {0x00000147} (int) )
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1981 AT_APPLE_property_attribute (DW_APPLE_PROPERTY_readonly, DW_APPLE_PROPERTY_nonatomic)
1982</pre>
1983</div>
1984
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1985<p> The setter and getter method names are attached to the property using
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1986DW_AT_APPLE_property_setter and DW_AT_APPLE_property_getter attributes.
1987</p>
1988<div class="doc_code">
1989<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1990@interface I1
1991@property (setter=myOwnP3Setter:) int p3;
1992-(void)myOwnP3Setter:(int)a;
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1993@end
1994
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1995@implementation I1
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1996@synthesize p3;
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1997-(void)myOwnP3Setter:(int)a{ }
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1998@end
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1999</pre>
2000</div>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2001
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2002<p>
2003The DWARF for this would be:
2004</p>
2005<div class="doc_code">
2006<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]20070x000003bd: TAG_structure_type [7] *
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2008 AT_APPLE_runtime_class( 0x10 )
2009 AT_name( "I1" )
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2010 AT_decl_file( "Objc_Property.m" )
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2011 AT_decl_line( 3 )
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2012
20130x000003cd TAG_APPLE_property
2014 AT_name ( "p3" )
2015 AT_APPLE_property_setter ( "myOwnP3Setter:" )
2016 AT_type( {0x00000147} ( int ) )
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2017
20180x000003f3: TAG_member [8]
2019 AT_name( "_p3" )
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2020 AT_type ( {0x00000147} ( int ) )
2021 AT_APPLE_property ( {0x000003cd} )
2022 AT_artificial ( 0x1 )
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2023</pre>
2024</div>
2025
2026</div>
2027
2028<!-- *********************************************************************** -->
2029<h4>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2030 <a name="objcpropertynewtags">New DWARF Tags</a>
2031</h4>
2032<!-- *********************************************************************** -->
2033
2034<div>
2035<table border="1" cellspacing="0">
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2036 <col width="200" />
2037 <col width="200" />
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2038 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2039 <th>TAG</th>
2040 <th>Value</th>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2041 </tr>
2042 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2043 <td>DW_TAG_APPLE_property</td>
2044 <td>0x4200</td>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2045 </tr>
2046</table>
2047
2048</div>
2049
2050<!-- *********************************************************************** -->
2051<h4>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2052 <a name="objcpropertynewattributes">New DWARF Attributes</a>
2053</h4>
2054<!-- *********************************************************************** -->
2055
2056<div>
2057<table border="1" cellspacing="0">
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2058 <col width="200" />
2059 <col width="200" />
2060 <col width="200" />
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2061 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2062 <th>Attribute</th>
2063 <th>Value</th>
2064 <th>Classes</th>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2065 </tr>
2066 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2067 <td>DW_AT_APPLE_property</td>
2068 <td>0x3fed</td>
2069 <td>Reference</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2070 </tr>
2071 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2072 <td>DW_AT_APPLE_property_getter</td>
2073 <td>0x3fe9</td>
2074 <td>String</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2075 </tr>
2076 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2077 <td>DW_AT_APPLE_property_setter</td>
2078 <td>0x3fea</td>
2079 <td>String</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2080 </tr>
2081 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2082 <td>DW_AT_APPLE_property_attribute</td>
2083 <td>0x3feb</td>
2084 <td>Constant</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2085 </tr>
2086</table>
2087
2088</div>
2089
2090<!-- *********************************************************************** -->
2091<h4>
2092 <a name="objcpropertynewconstants">New DWARF Constants</a>
2093</h4>
2094<!-- *********************************************************************** -->
2095
2096<div>
2097<table border="1" cellspacing="0">
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2098 <col width="200" />
2099 <col width="200" />
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2100 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2101 <th>Name</th>
2102 <th>Value</th>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2103 </tr>
2104 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2105 <td>DW_AT_APPLE_PROPERTY_readonly</td>
2106 <td>0x1</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_readwrite</td>
2110 <td>0x2</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2111 </tr>
2112 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2113 <td>DW_AT_APPLE_PROPERTY_assign</td>
2114 <td>0x4</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2115 </tr>
2116 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2117 <td>DW_AT_APPLE_PROPERTY_retain</td>
2118 <td>0x8</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2119 </tr>
2120 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2121 <td>DW_AT_APPLE_PROPERTY_copy</td>
2122 <td>0x10</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2123 </tr>
2124 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame^]2125 <td>DW_AT_APPLE_PROPERTY_nonatomic</td>
2126 <td>0x20</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2127 </tr>
2128</table>
2129
2130</div>
2131</div>
2132</div>
2133
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2134<div>
2135<!-- ======================================================================= -->
2136<h3>
2137 <a name="acceltable">Name Accelerator Tables</a>
2138</h3>
2139<!-- ======================================================================= -->
2140<!-- ======================================================================= -->
2141<h4>
Eric Christopher5b7634f2012-03-06 02:25:41 +0000[diff] [blame]2142 <a name="acceltableintroduction">Introduction</a>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2143</h4>
2144<!-- ======================================================================= -->
2145<div>
2146<p>The .debug_pubnames and .debug_pubtypes formats are not what a debugger
2147 needs. The "pub" in the section name indicates that the entries in the
2148 table are publicly visible names only. This means no static or hidden
2149 functions show up in the .debug_pubnames. No static variables or private class
2150 variables are in the .debug_pubtypes. Many compilers add different things to
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2151 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]2152
2153<p>The typical query given by users tends not to match up with the contents of
2154 these tables. For example, the DWARF spec states that "In the case of the
2155 name of a function member or static data member of a C++ structure, class or
2156 union, the name presented in the .debug_pubnames section is not the simple
2157 name given by the DW_AT_name attribute of the referenced debugging information
2158 entry, but rather the fully qualified name of the data or function member."
2159 So the only names in these tables for complex C++ entries is a fully
2160 qualified name. Debugger users tend not to enter their search strings as
2161 "a::b::c(int,const Foo&) const", but rather as "c", "b::c" , or "a::b::c". So
2162 the name entered in the name table must be demangled in order to chop it up
2163 appropriately and additional names must be manually entered into the table
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2164 to make it effective as a name lookup table for debuggers to use.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2165
2166<p>All debuggers currently ignore the .debug_pubnames table as a result of
2167 its inconsistent and useless public-only name content making it a waste of
2168 space in the object file. These tables, when they are written to disk, are
2169 not sorted in any way, leaving every debugger to do its own parsing
2170 and sorting. These tables also include an inlined copy of the string values
2171 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]2172 disk, especially for large C++ programs.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2173
2174<p>Can't we just fix the sections by adding all of the names we need to this
2175 table? No, because that is not what the tables are defined to contain and we
2176 won't know the difference between the old bad tables and the new good tables.
2177 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]2178 we need.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2179
2180<p>These tables are also insufficient for what a debugger like LLDB needs.
2181 LLDB uses clang for its expression parsing where LLDB acts as a PCH. LLDB is
2182 then often asked to look for type "foo" or namespace "bar", or list items in
2183 namespace "baz". Namespaces are not included in the pubnames or pubtypes
2184 tables. Since clang asks a lot of questions when it is parsing an expression,
2185 we need to be very fast when looking up names, as it happens a lot. Having new
2186 accelerator tables that are optimized for very quick lookups will benefit
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2187 this type of debugging experience greatly.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2188
2189<p>We would like to generate name lookup tables that can be mapped into
2190 memory from disk, and used as is, with little or no up-front parsing. We would
2191 also be able to control the exact content of these different tables so they
2192 contain exactly what we need. The Name Accelerator Tables were designed
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2193 to fix these issues. In order to solve these issues we need to:</p>
2194
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2195<ul>
2196 <li>Have a format that can be mapped into memory from disk and used as is</li>
2197 <li>Lookups should be very fast</li>
2198 <li>Extensible table format so these tables can be made by many producers</li>
2199 <li>Contain all of the names needed for typical lookups out of the box</li>
2200 <li>Strict rules for the contents of tables</li>
2201</ul>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2202
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2203<p>Table size is important and the accelerator table format should allow the
2204 reuse of strings from common string tables so the strings for the names are
2205 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]2206 by simply mapping the table into memory with minimal header parsing.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2207
2208<p>The name lookups need to be fast and optimized for the kinds of lookups
2209 that debuggers tend to do. Optimally we would like to touch as few parts of
2210 the mapped table as possible when doing a name lookup and be able to quickly
2211 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]2212 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]2213
2214<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]2215 the accelerator tables and documented so clients can rely on the content.</p>
2216
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2217</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2218
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2219<!-- ======================================================================= -->
2220<h4>
2221 <a name="acceltablehashes">Hash Tables</a>
2222</h4>
2223<!-- ======================================================================= -->
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2224
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2225<div>
2226<h5>Standard Hash Tables</h5>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2227
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2228<p>Typical hash tables have a header, buckets, and each bucket points to the
2229bucket contents:
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2230</p>
2231
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2232<div class="doc_code">
2233<pre>
2234.------------.
2235| HEADER |
2236|------------|
2237| BUCKETS |
2238|------------|
2239| DATA |
2240`------------'
2241</pre>
2242</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2243
2244<p>The BUCKETS are an array of offsets to DATA for each hash:</p>
2245
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2246<div class="doc_code">
2247<pre>
2248.------------.
2249| 0x00001000 | BUCKETS[0]
2250| 0x00002000 | BUCKETS[1]
2251| 0x00002200 | BUCKETS[2]
2252| 0x000034f0 | BUCKETS[3]
2253| | ...
2254| 0xXXXXXXXX | BUCKETS[n_buckets]
2255'------------'
2256</pre>
2257</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2258
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2259<p>So for bucket[3] in the example above, we have an offset into the table
2260 0x000034f0 which points to a chain of entries for the bucket. Each bucket
2261 must contain a next pointer, full 32 bit hash value, the string itself,
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2262 and the data for the current string value.</p>
2263
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2264<div class="doc_code">
2265<pre>
2266 .------------.
22670x000034f0: | 0x00003500 | next pointer
2268 | 0x12345678 | 32 bit hash
2269 | "erase" | string value
2270 | data[n] | HashData for this bucket
2271 |------------|
22720x00003500: | 0x00003550 | next pointer
2273 | 0x29273623 | 32 bit hash
2274 | "dump" | string value
2275 | data[n] | HashData for this bucket
2276 |------------|
22770x00003550: | 0x00000000 | next pointer
2278 | 0x82638293 | 32 bit hash
2279 | "main" | string value
2280 | data[n] | HashData for this bucket
2281 `------------'
2282</pre>
2283</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2284
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2285<p>The problem with this layout for debuggers is that we need to optimize for
2286 the negative lookup case where the symbol we're searching for is not present.
2287 So if we were to lookup "printf" in the table above, we would make a 32 hash
2288 for "printf", it might match bucket[3]. We would need to go to the offset
2289 0x000034f0 and start looking to see if our 32 bit hash matches. To do so, we
2290 need to read the next pointer, then read the hash, compare it, and skip to
2291 the next bucket. Each time we are skipping many bytes in memory and touching
2292 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]2293 accesses then tell us that we didn't have a match.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2294
2295<h5>Name Hash Tables</h5>
2296
2297<p>To solve the issues mentioned above we have structured the hash tables
2298 a bit differently: a header, buckets, an array of all unique 32 bit hash
2299 values, followed by an array of hash value data offsets, one for each hash
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2300 value, then the data for all hash values:</p>
2301
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2302<div class="doc_code">
2303<pre>
2304.-------------.
2305| HEADER |
2306|-------------|
2307| BUCKETS |
2308|-------------|
2309| HASHES |
2310|-------------|
2311| OFFSETS |
2312|-------------|
2313| DATA |
2314`-------------'
2315</pre>
2316</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2317
Eric Christopher5b7634f2012-03-06 02:25:41 +0000[diff] [blame]2318<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]2319 making all of the full 32 bit hash values contiguous in memory, we allow
2320 ourselves to efficiently check for a match while touching as little
Eric Christopher5b7634f2012-03-06 02:25:41 +0000[diff] [blame]2321 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]2322 the lookup goes. If it does match, it usually is a match with no collisions.
2323 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]2324 values, we can clarify the contents of the BUCKETS, HASHES and OFFSETS as:</p>
2325
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2326<div class="doc_code">
2327<pre>
2328.-------------------------.
2329| HEADER.magic | uint32_t
2330| HEADER.version | uint16_t
2331| HEADER.hash_function | uint16_t
2332| HEADER.bucket_count | uint32_t
2333| HEADER.hashes_count | uint32_t
2334| HEADER.header_data_len | uint32_t
2335| HEADER_DATA | HeaderData
2336|-------------------------|
2337| BUCKETS | uint32_t[n_buckets] // 32 bit hash indexes
2338|-------------------------|
2339| HASHES | uint32_t[n_buckets] // 32 bit hash values
2340|-------------------------|
2341| OFFSETS | uint32_t[n_buckets] // 32 bit offsets to hash value data
2342|-------------------------|
2343| ALL HASH DATA |
2344`-------------------------'
2345</pre>
2346</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2347
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2348<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]2349 with:</p>
2350
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2351<div class="doc_code">
2352<pre>
2353 .------------.
2354 | HEADER |
2355 |------------|
2356 | 0 | BUCKETS[0]
2357 | 2 | BUCKETS[1]
2358 | 5 | BUCKETS[2]
2359 | 6 | BUCKETS[3]
2360 | | ...
2361 | ... | BUCKETS[n_buckets]
2362 |------------|
2363 | 0x........ | HASHES[0]
2364 | 0x........ | HASHES[1]
2365 | 0x........ | HASHES[2]
2366 | 0x........ | HASHES[3]
2367 | 0x........ | HASHES[4]
2368 | 0x........ | HASHES[5]
2369 | 0x12345678 | HASHES[6] hash for BUCKETS[3]
2370 | 0x29273623 | HASHES[7] hash for BUCKETS[3]
2371 | 0x82638293 | HASHES[8] hash for BUCKETS[3]
2372 | 0x........ | HASHES[9]
2373 | 0x........ | HASHES[10]
2374 | 0x........ | HASHES[11]
2375 | 0x........ | HASHES[12]
2376 | 0x........ | HASHES[13]
2377 | 0x........ | HASHES[n_hashes]
2378 |------------|
2379 | 0x........ | OFFSETS[0]
2380 | 0x........ | OFFSETS[1]
2381 | 0x........ | OFFSETS[2]
2382 | 0x........ | OFFSETS[3]
2383 | 0x........ | OFFSETS[4]
2384 | 0x........ | OFFSETS[5]
2385 | 0x000034f0 | OFFSETS[6] offset for BUCKETS[3]
2386 | 0x00003500 | OFFSETS[7] offset for BUCKETS[3]
2387 | 0x00003550 | OFFSETS[8] offset for BUCKETS[3]
2388 | 0x........ | OFFSETS[9]
2389 | 0x........ | OFFSETS[10]
2390 | 0x........ | OFFSETS[11]
2391 | 0x........ | OFFSETS[12]
2392 | 0x........ | OFFSETS[13]
2393 | 0x........ | OFFSETS[n_hashes]
2394 |------------|
2395 | |
2396 | |
2397 | |
2398 | |
2399 | |
2400 |------------|
24010x000034f0: | 0x00001203 | .debug_str ("erase")
2402 | 0x00000004 | A 32 bit array count - number of HashData with name "erase"
2403 | 0x........ | HashData[0]
2404 | 0x........ | HashData[1]
2405 | 0x........ | HashData[2]
2406 | 0x........ | HashData[3]
2407 | 0x00000000 | String offset into .debug_str (terminate data for hash)
2408 |------------|
24090x00003500: | 0x00001203 | String offset into .debug_str ("collision")
2410 | 0x00000002 | A 32 bit array count - number of HashData with name "collision"
2411 | 0x........ | HashData[0]
2412 | 0x........ | HashData[1]
2413 | 0x00001203 | String offset into .debug_str ("dump")
2414 | 0x00000003 | A 32 bit array count - number of HashData with name "dump"
2415 | 0x........ | HashData[0]
2416 | 0x........ | HashData[1]
2417 | 0x........ | HashData[2]
2418 | 0x00000000 | String offset into .debug_str (terminate data for hash)
2419 |------------|
24200x00003550: | 0x00001203 | String offset into .debug_str ("main")
2421 | 0x00000009 | A 32 bit array count - number of HashData with name "main"
2422 | 0x........ | HashData[0]
2423 | 0x........ | HashData[1]
2424 | 0x........ | HashData[2]
2425 | 0x........ | HashData[3]
2426 | 0x........ | HashData[4]
2427 | 0x........ | HashData[5]
2428 | 0x........ | HashData[6]
2429 | 0x........ | HashData[7]
2430 | 0x........ | HashData[8]
2431 | 0x00000000 | String offset into .debug_str (terminate data for hash)
2432 `------------'
2433</pre>
2434</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2435
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2436<p>So we still have all of the same data, we just organize it more efficiently
2437 for debugger lookup. If we repeat the same "printf" lookup from above, we
2438 would hash "printf" and find it matches BUCKETS[3] by taking the 32 bit hash
2439 value and modulo it by n_buckets. BUCKETS[3] contains "6" which is the index
2440 into the HASHES table. We would then compare any consecutive 32 bit hashes
2441 values in the HASHES array as long as the hashes would be in BUCKETS[3]. We
2442 do this by verifying that each subsequent hash value modulo n_buckets is still
2443 3. In the case of a failed lookup we would access the memory for BUCKETS[3], and
2444 then compare a few consecutive 32 bit hashes before we know that we have no match.
2445 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]2446 number of processor data cache lines being accessed as small as possible.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2447
2448<p>The string hash that is used for these lookup tables is the Daniel J.
2449 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]2450 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]2451
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2452<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]2453</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2454
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2455<!-- ======================================================================= -->
2456<h4>
2457 <a name="acceltabledetails">Details</a>
2458</h4>
2459<!-- ======================================================================= -->
2460<div>
2461<p>These name hash tables are designed to be generic where specializations of
2462 the table get to define additional data that goes into the header
2463 ("HeaderData"), how the string value is stored ("KeyType") and the content
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2464 of the data for each hash value.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2465
2466<h5>Header Layout</h5>
2467<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]2468 the header is:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2469<div class="doc_code">
2470<pre>
2471struct Header
2472{
2473 uint32_t magic; // 'HASH' magic value to allow endian detection
2474 uint16_t version; // Version number
2475 uint16_t hash_function; // The hash function enumeration that was used
2476 uint32_t bucket_count; // The number of buckets in this hash table
2477 uint32_t hashes_count; // The total number of unique hash values and hash data offsets in this table
2478 uint32_t header_data_len; // The bytes to skip to get to the hash indexes (buckets) for correct alignment
2479 // Specifically the length of the following HeaderData field - this does not
2480 // include the size of the preceding fields
2481 HeaderData header_data; // Implementation specific header data
2482};
2483</pre>
2484</div>
2485<p>The header starts with a 32 bit "magic" value which must be 'HASH' encoded as
2486 an ASCII integer. This allows the detection of the start of the hash table and
2487 also allows the table's byte order to be determined so the table can be
2488 correctly extracted. The "magic" value is followed by a 16 bit version number
2489 which allows the table to be revised and modified in the future. The current
2490 version number is 1. "hash_function" is a uint16_t enumeration that specifies
2491 which hash function was used to produce this table. The current values for the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2492 hash function enumerations include:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2493<div class="doc_code">
2494<pre>
2495enum HashFunctionType
2496{
2497 eHashFunctionDJB = 0u, // Daniel J Bernstein hash function
2498};
2499</pre>
2500</div>
2501<p>"bucket_count" is a 32 bit unsigned integer that represents how many buckets
2502 are in the BUCKETS array. "hashes_count" is the number of unique 32 bit hash
2503 values that are in the HASHES array, and is the same number of offsets are
2504 contained in the OFFSETS array. "header_data_len" specifies the size in
2505 bytes of the HeaderData that is filled in by specialized versions of this
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2506 table.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2507
2508<h5>Fixed Lookup</h5>
2509<p>The header is followed by the buckets, hashes, offsets, and hash value
2510 data.
2511<div class="doc_code">
2512<pre>
2513struct FixedTable
2514{
2515 uint32_t buckets[Header.bucket_count]; // An array of hash indexes into the "hashes[]" array below
2516 uint32_t hashes [Header.hashes_count]; // Every unique 32 bit hash for the entire table is in this table
2517 uint32_t offsets[Header.hashes_count]; // An offset that corresponds to each item in the "hashes[]" array above
2518};
2519</pre>
2520</div>
2521<p>"buckets" is an array of 32 bit indexes into the "hashes" array. The
2522 "hashes" array contains all of the 32 bit hash values for all names in the
2523 hash table. Each hash in the "hashes" table has an offset in the "offsets"
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2524 array that points to the data for the hash value.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2525
2526<p>This table setup makes it very easy to repurpose these tables to contain
2527 different data, while keeping the lookup mechanism the same for all tables.
2528 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]2529 later and do very efficient name lookups with little or no parsing.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2530
2531<p>DWARF lookup tables can be implemented in a variety of ways and can store
2532 a lot of information for each name. We want to make the DWARF tables
2533 extensible and able to store the data efficiently so we have used some of the
2534 DWARF features that enable efficient data storage to define exactly what kind
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2535 of data we store for each name.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2536
2537<p>The "HeaderData" contains a definition of the contents of each HashData
2538 chunk. We might want to store an offset to all of the debug information
2539 entries (DIEs) for each name. To keep things extensible, we create a list of
2540 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]2541 type of the data in each atom:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2542<div class="doc_code">
2543<pre>
2544enum AtomType
2545{
2546 eAtomTypeNULL = 0u,
2547 eAtomTypeDIEOffset = 1u, // DIE offset, check form for encoding
2548 eAtomTypeCUOffset = 2u, // DIE offset of the compiler unit header that contains the item in question
2549 eAtomTypeTag = 3u, // DW_TAG_xxx value, should be encoded as DW_FORM_data1 (if no tags exceed 255) or DW_FORM_data2
2550 eAtomTypeNameFlags = 4u, // Flags from enum NameFlags
2551 eAtomTypeTypeFlags = 5u, // Flags from enum TypeFlags
2552};
2553</pre>
2554</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2555<p>The enumeration values and their meanings are:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2556<div class="doc_code">
2557<pre>
2558 eAtomTypeNULL - a termination atom that specifies the end of the atom list
2559 eAtomTypeDIEOffset - an offset into the .debug_info section for the DWARF DIE for this name
2560 eAtomTypeCUOffset - an offset into the .debug_info section for the CU that contains the DIE
2561 eAtomTypeDIETag - The DW_TAG_XXX enumeration value so you don't have to parse the DWARF to see what it is
2562 eAtomTypeNameFlags - Flags for functions and global variables (isFunction, isInlined, isExternal...)
2563 eAtomTypeTypeFlags - Flags for types (isCXXClass, isObjCClass, ...)
2564</pre>
2565</div>
2566<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]2567 each atom type data is encoded:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2568<div class="doc_code">
2569<pre>
2570struct Atom
2571{
2572 uint16_t type; // AtomType enum value
2573 uint16_t form; // DWARF DW_FORM_XXX defines
2574};
2575</pre>
2576</div>
2577<p>The "form" type above is from the DWARF specification and defines the
2578 exact encoding of the data for the Atom type. See the DWARF specification for
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2579 the DW_FORM_ definitions.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2580<div class="doc_code">
2581<pre>
2582struct HeaderData
2583{
2584 uint32_t die_offset_base;
2585 uint32_t atom_count;
2586 Atoms atoms[atom_count0];
2587};
2588</pre>
2589</div>
2590<p>"HeaderData" defines the base DIE offset that should be added to any atoms
2591 that are encoded using the DW_FORM_ref1, DW_FORM_ref2, DW_FORM_ref4,
2592 DW_FORM_ref8 or DW_FORM_ref_udata. It also defines what is contained in
2593 each "HashData" object -- Atom.form tells us how large each field will be in
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2594 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]2595
2596<p>For the current implementations of the ".apple_names" (all functions + globals),
2597 the ".apple_types" (names of all types that are defined), and the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2598 ".apple_namespaces" (all namespaces), we currently set the Atom array to be:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2599<div class="doc_code">
2600<pre>
2601HeaderData.atom_count = 1;
2602HeaderData.atoms[0].type = eAtomTypeDIEOffset;
2603HeaderData.atoms[0].form = DW_FORM_data4;
2604</pre>
2605</div>
2606<p>This defines the contents to be the DIE offset (eAtomTypeDIEOffset) that is
2607 encoded as a 32 bit value (DW_FORM_data4). This allows a single name to have
2608 multiple matching DIEs in a single file, which could come up with an inlined
2609 function for instance. Future tables could include more information about the
2610 DIE such as flags indicating if the DIE is a function, method, block,
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2611 or inlined.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2612
2613<p>The KeyType for the DWARF table is a 32 bit string table offset into the
2614 ".debug_str" table. The ".debug_str" is the string table for the DWARF which
2615 may already contain copies of all of the strings. This helps make sure, with
2616 help from the compiler, that we reuse the strings between all of the DWARF
2617 sections and keeps the hash table size down. Another benefit to having the
2618 compiler generate all strings as DW_FORM_strp in the debug info, is that
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2619 DWARF parsing can be made much faster.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2620
2621<p>After a lookup is made, we get an offset into the hash data. The hash data
2622 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]2623 at the offset in the hash data consists of a triple:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2624<div class="doc_code">
2625<pre>
2626uint32_t str_offset
2627uint32_t hash_data_count
2628HashData[hash_data_count]
2629</pre>
2630</div>
2631<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]2632 hash data chunks contain a single item (no 32 bit hash collision):</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2633<div class="doc_code">
2634<pre>
2635.------------.
2636| 0x00001023 | uint32_t KeyType (.debug_str[0x0001023] => "main")
2637| 0x00000004 | uint32_t HashData count
2638| 0x........ | uint32_t HashData[0] DIE offset
2639| 0x........ | uint32_t HashData[1] DIE offset
2640| 0x........ | uint32_t HashData[2] DIE offset
2641| 0x........ | uint32_t HashData[3] DIE offset
2642| 0x00000000 | uint32_t KeyType (end of hash chain)
2643`------------'
2644</pre>
2645</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2646<p>If there are collisions, you will have multiple valid string offsets:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2647<div class="doc_code">
2648<pre>
2649.------------.
2650| 0x00001023 | uint32_t KeyType (.debug_str[0x0001023] => "main")
2651| 0x00000004 | uint32_t HashData count
2652| 0x........ | uint32_t HashData[0] DIE offset
2653| 0x........ | uint32_t HashData[1] DIE offset
2654| 0x........ | uint32_t HashData[2] DIE offset
2655| 0x........ | uint32_t HashData[3] DIE offset
2656| 0x00002023 | uint32_t KeyType (.debug_str[0x0002023] => "print")
2657| 0x00000002 | uint32_t HashData count
2658| 0x........ | uint32_t HashData[0] DIE offset
2659| 0x........ | uint32_t HashData[1] DIE offset
2660| 0x00000000 | uint32_t KeyType (end of hash chain)
2661`------------'
2662</pre>
2663</div>
2664<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]2665 32 bit hash collision per 100,000 name entries.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2666</div>
2667<!-- ======================================================================= -->
2668<h4>
2669 <a name="acceltablecontents">Contents</a>
2670</h4>
2671<!-- ======================================================================= -->
2672<div>
2673<p>As we said, we want to strictly define exactly what is included in the
2674 different tables. For DWARF, we have 3 tables: ".apple_names", ".apple_types",
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2675 and ".apple_namespaces".</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2676
2677<p>".apple_names" sections should contain an entry for each DWARF DIE whose
2678 DW_TAG is a DW_TAG_label, DW_TAG_inlined_subroutine, or DW_TAG_subprogram that
2679 has address attributes: DW_AT_low_pc, DW_AT_high_pc, DW_AT_ranges or
2680 DW_AT_entry_pc. It also contains DW_TAG_variable DIEs that have a DW_OP_addr
2681 in the location (global and static variables). All global and static variables
2682 should be included, including those scoped withing functions and classes. For
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2683 example using the following code:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2684<div class="doc_code">
2685<pre>
2686static int var = 0;
2687
2688void f ()
2689{
2690 static int var = 0;
2691}
2692</pre>
2693</div>
2694<p>Both of the static "var" variables would be included in the table. All
2695 functions should emit both their full names and their basenames. For C or C++,
2696 the full name is the mangled name (if available) which is usually in the
2697 DW_AT_MIPS_linkage_name attribute, and the DW_AT_name contains the function
2698 basename. If global or static variables have a mangled name in a
2699 DW_AT_MIPS_linkage_name attribute, this should be emitted along with the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2700 simple name found in the DW_AT_name attribute.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2701
2702<p>".apple_types" sections should contain an entry for each DWARF DIE whose
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2703 tag is one of:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2704<ul>
2705 <li>DW_TAG_array_type</li>
2706 <li>DW_TAG_class_type</li>
2707 <li>DW_TAG_enumeration_type</li>
2708 <li>DW_TAG_pointer_type</li>
2709 <li>DW_TAG_reference_type</li>
2710 <li>DW_TAG_string_type</li>
2711 <li>DW_TAG_structure_type</li>
2712 <li>DW_TAG_subroutine_type</li>
2713 <li>DW_TAG_typedef</li>
2714 <li>DW_TAG_union_type</li>
2715 <li>DW_TAG_ptr_to_member_type</li>
2716 <li>DW_TAG_set_type</li>
2717 <li>DW_TAG_subrange_type</li>
2718 <li>DW_TAG_base_type</li>
2719 <li>DW_TAG_const_type</li>
2720 <li>DW_TAG_constant</li>
2721 <li>DW_TAG_file_type</li>
2722 <li>DW_TAG_namelist</li>
2723 <li>DW_TAG_packed_type</li>
2724 <li>DW_TAG_volatile_type</li>
2725 <li>DW_TAG_restrict_type</li>
2726 <li>DW_TAG_interface_type</li>
2727 <li>DW_TAG_unspecified_type</li>
2728 <li>DW_TAG_shared_type</li>
2729</ul>
2730<p>Only entries with a DW_AT_name attribute are included, and the entry must
2731 not be a forward declaration (DW_AT_declaration attribute with a non-zero value).
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2732 For example, using the following code:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2733<div class="doc_code">
2734<pre>
2735int main ()
2736{
2737 int *b = 0;
2738 return *b;
2739}
2740</pre>
2741</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2742<p>We get a few type DIEs:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2743<div class="doc_code">
2744<pre>
27450x00000067: TAG_base_type [5]
2746 AT_encoding( DW_ATE_signed )
2747 AT_name( "int" )
2748 AT_byte_size( 0x04 )
2749
27500x0000006e: TAG_pointer_type [6]
2751 AT_type( {0x00000067} ( int ) )
2752 AT_byte_size( 0x08 )
2753</pre>
2754</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2755<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]2756
2757<p>".apple_namespaces" section should contain all DW_TAG_namespace DIEs. If
2758 we run into a namespace that has no name this is an anonymous namespace,
2759 and the name should be output as "(anonymous namespace)" (without the quotes).
2760 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]2761 C++ library that demangles mangled names.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2762</div>
2763
2764<!-- ======================================================================= -->
2765<h4>
2766 <a name="acceltableextensions">Language Extensions and File Format Changes</a>
2767</h4>
2768<!-- ======================================================================= -->
2769<div>
2770<h5>Objective-C Extensions</h5>
2771<p>".apple_objc" section should contain all DW_TAG_subprogram DIEs for an
2772 Objective-C class. The name used in the hash table is the name of the
2773 Objective-C class itself. If the Objective-C class has a category, then an
2774 entry is made for both the class name without the category, and for the class
2775 name with the category. So if we have a DIE at offset 0x1234 with a name
2776 of method "-[NSString(my_additions) stringWithSpecialString:]", we would add
2777 an entry for "NSString" that points to DIE 0x1234, and an entry for
2778 "NSString(my_additions)" that points to 0x1234. This allows us to quickly
2779 track down all Objective-C methods for an Objective-C class when doing
2780 expressions. It is needed because of the dynamic nature of Objective-C where
2781 anyone can add methods to a class. The DWARF for Objective-C methods is also
2782 emitted differently from C++ classes where the methods are not usually
2783 contained in the class definition, they are scattered about across one or more
2784 compile units. Categories can also be defined in different shared libraries.
2785 So we need to be able to quickly find all of the methods and class functions
2786 given the Objective-C class name, or quickly find all methods and class
2787 functions for a class + category name. This table does not contain any selector
2788 names, it just maps Objective-C class names (or class names + category) to all
2789 of the methods and class functions. The selectors are added as function
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2790 basenames in the .debug_names section.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2791
2792<p>In the ".apple_names" section for Objective-C functions, the full name is the
2793 entire function name with the brackets ("-[NSString stringWithCString:]") and the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2794 basename is the selector only ("stringWithCString:").</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2795
2796<h5>Mach-O Changes</h5>
2797<p>The sections names for the apple hash tables are for non mach-o files. For
2798 mach-o files, the sections should be contained in the "__DWARF" segment with
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2799 names as follows:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2800<ul>
2801 <li>".apple_names" -> "__apple_names"</li>
2802 <li>".apple_types" -> "__apple_types"</li>
2803 <li>".apple_namespaces" -> "__apple_namespac" (16 character limit)</li>
2804 <li> ".apple_objc" -> "__apple_objc"</li>
2805</ul>
2806</div>
2807</div>
2808
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2809<!-- *********************************************************************** -->
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2810
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2811<hr>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2812<address>
2813 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]2814 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2815 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]2816 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]2817
2818 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
NAKAMURA Takumib9a33632011-04-09 02:13:37 +0000[diff] [blame]2819 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2820 Last modified: $Date$
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2821</address>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2822
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