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Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]6 <title>Source Level Debugging with LLVM</title>
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9<body>
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</tr></table>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]81
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]82<div class="doc_author">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]83 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
Jim Laskeyc760a922007-03-14 19:32:21 +0000[diff] [blame]84 and <a href="mailto:jlaskey@mac.com">Jim Laskey</a></p>
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]85</div>
86
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]87
88<!-- *********************************************************************** -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]89<h2><a name="introduction">Introduction</a></h2>
Misha Brukman94218a72004-12-09 20:27:37 +0000[diff] [blame]90<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]91
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]92<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]93
94<p>This document is the central repository for all information pertaining to
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]95 debug information in LLVM. It describes the <a href="#format">actual format
96 that the LLVM debug information</a> takes, which is useful for those
97 interested in creating front-ends or dealing directly with the information.
Chris Lattner8ad2f982009-07-18 21:47:15 +0000[diff] [blame]98 Further, this document provides specific examples of what debug information
Chris Lattner89940752011-01-18 06:12:10 +0000[diff] [blame]99 for C/C++ looks like.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]100
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]101<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]102<h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]103 <a name="phil">Philosophy behind LLVM debugging information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]104</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]105
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]106<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]107
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]108<p>The idea of the LLVM debugging information is to capture how the important
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]109 pieces of the source-language's Abstract Syntax Tree map onto LLVM code.
110 Several design aspects have shaped the solution that appears here. The
111 important ones are:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]112
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]113<ul>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]114 <li>Debugging information should have very little impact on the rest of the
115 compiler. No transformations, analyses, or code generators should need to
116 be modified because of debugging information.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]117
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]118 <li>LLVM optimizations should interact in <a href="#debugopt">well-defined and
119 easily described ways</a> with the debugging information.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]120
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]121 <li>Because LLVM is designed to support arbitrary programming languages,
122 LLVM-to-LLVM tools should not need to know anything about the semantics of
123 the source-level-language.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]124
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]125 <li>Source-level languages are often <b>widely</b> different from one another.
126 LLVM should not put any restrictions of the flavor of the source-language,
127 and the debugging information should work with any 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>With code generator support, it should be possible to use an LLVM compiler
130 to compile a program to native machine code and standard debugging
131 formats. This allows compatibility with traditional machine-code level
132 debuggers, like GDB or DBX.</li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]133</ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]134
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]135<p>The approach used by the LLVM implementation is to use a small set
136 of <a href="#format_common_intrinsics">intrinsic functions</a> to define a
137 mapping between LLVM program objects and the source-level objects. The
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]138 description of the source-level program is maintained in LLVM metadata
139 in an <a href="#ccxx_frontend">implementation-defined format</a>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]140 (the C/C++ front-end currently uses working draft 7 of
141 the <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3
142 standard</a>).</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]143
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]144<p>When a program is being debugged, a debugger interacts with the user and
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]145 turns the stored debug information into source-language specific information.
146 As such, a debugger must be aware of the source-language, and is thus tied to
147 a specific language or family of languages.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]148
149</div>
150
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]151<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]152<h3>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]153 <a name="consumers">Debug information consumers</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]154</h3>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]155
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]156<div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]157
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]158<p>The role of debug information is to provide meta information normally
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]159 stripped away during the compilation process. This meta information provides
160 an LLVM user a relationship between generated code and the original program
161 source code.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]162
Chris Lattnerc3107782010-04-05 04:11:11 +0000[diff] [blame]163<p>Currently, debug information is consumed by DwarfDebug to produce dwarf
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]164 information used by the gdb debugger. Other targets could use the same
165 information to produce stabs or other debug forms.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]166
167<p>It would also be reasonable to use debug information to feed profiling tools
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]168 for analysis of generated code, or, tools for reconstructing the original
169 source from generated code.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]170
171<p>TODO - expound a bit more.</p>
172
173</div>
174
175<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]176<h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]177 <a name="debugopt">Debugging optimized code</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]178</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]179
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]180<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]181
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]182<p>An extremely high priority of LLVM debugging information is to make it
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]183 interact well with optimizations and analysis. In particular, the LLVM debug
184 information provides the following guarantees:</p>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]185
186<ul>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]187 <li>LLVM debug information <b>always provides information to accurately read
188 the source-level state of the program</b>, regardless of which LLVM
189 optimizations have been run, and without any modification to the
190 optimizations themselves. However, some optimizations may impact the
191 ability to modify the current state of the program with a debugger, such
192 as setting program variables, or calling functions that have been
193 deleted.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]194
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]195 <li>As desired, LLVM optimizations can be upgraded to be aware of the LLVM
196 debugging information, allowing them to update the debugging information
197 as they perform aggressive optimizations. This means that, with effort,
198 the LLVM optimizers could optimize debug code just as well as non-debug
199 code.</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]200
Devang Patele0bdc592011-05-31 17:45:27 +0000[diff] [blame]201 <li>LLVM debug information does not prevent optimizations from
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]202 happening (for example inlining, basic block reordering/merging/cleanup,
Devang Patelf729e912011-05-31 18:06:14 +0000[diff] [blame]203 tail duplication, etc).</li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]204
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]205 <li>LLVM debug information is automatically optimized along with the rest of
206 the program, using existing facilities. For example, duplicate
207 information is automatically merged by the linker, and unused information
208 is automatically removed.</li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]209</ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]210
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]211<p>Basically, the debug information allows you to compile a program with
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]212 "<tt>-O0 -g</tt>" and get full debug information, allowing you to arbitrarily
213 modify the program as it executes from a debugger. Compiling a program with
214 "<tt>-O3 -g</tt>" gives you full debug information that is always available
215 and accurate for reading (e.g., you get accurate stack traces despite tail
216 call elimination and inlining), but you might lose the ability to modify the
217 program and call functions where were optimized out of the program, or
218 inlined away completely.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]219
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]220<p><a href="TestingGuide.html#quicktestsuite">LLVM test suite</a> provides a
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]221 framework to test optimizer's handling of debugging information. It can be
222 run like this:</p>
Devang Patela5c05aa2008-11-21 19:35:57 +0000[diff] [blame]223
224<div class="doc_code">
225<pre>
226% cd llvm/projects/test-suite/MultiSource/Benchmarks # or some other level
227% make TEST=dbgopt
228</pre>
229</div>
230
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]231<p>This will test impact of debugging information on optimization passes. If
232 debugging information influences optimization passes then it will be reported
233 as a failure. See <a href="TestingGuide.html">TestingGuide</a> for more
234 information on LLVM test infrastructure and how to run various tests.</p>
Devang Patela5c05aa2008-11-21 19:35:57 +0000[diff] [blame]235
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]236</div>
237
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]238</div>
239
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]240<!-- *********************************************************************** -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]241<h2>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]242 <a name="format">Debugging information format</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]243</h2>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]244<!-- *********************************************************************** -->
245
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]246<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]247
248<p>LLVM debugging information has been carefully designed to make it possible
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]249 for the optimizer to optimize the program and debugging information without
250 necessarily having to know anything about debugging information. In
John Criswellb34500f2010-03-17 15:01:50 +0000[diff] [blame]251 particular, the use of metadata avoids duplicated debugging information from
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]252 the beginning, and the global dead code elimination pass automatically
253 deletes debugging information for a function if it decides to delete the
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]254 function. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]255
256<p>To do this, most of the debugging information (descriptors for types,
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]257 variables, functions, source files, etc) is inserted by the language
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]258 front-end in the form of LLVM metadata. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]259
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]260<p>Debug information is designed to be agnostic about the target debugger and
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]261 debugging information representation (e.g. DWARF/Stabs/etc). It uses a
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]262 generic pass to decode the information that represents variables, types,
263 functions, namespaces, etc: this allows for arbitrary source-language
264 semantics and type-systems to be used, as long as there is a module
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]265 written for the target debugger to interpret the information. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]266
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]267<p>To provide basic functionality, the LLVM debugger does have to make some
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]268 assumptions about the source-level language being debugged, though it keeps
269 these to a minimum. The only common features that the LLVM debugger assumes
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]270 exist are <a href="#format_files">source files</a>,
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]271 and <a href="#format_global_variables">program objects</a>. These abstract
272 objects are used by a debugger to form stack traces, show information about
273 local variables, etc.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]274
275<p>This section of the documentation first describes the representation aspects
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]276 common to any source-language. The <a href="#ccxx_frontend">next section</a>
277 describes the data layout conventions used by the C and C++ front-ends.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]278
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]279<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]280<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]281 <a name="debug_info_descriptors">Debug information descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]282</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]283
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]284<div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]285
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]286<p>In consideration of the complexity and volume of debug information, LLVM
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]287 provides a specification for well formed debug descriptors. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]288
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]289<p>Consumers of LLVM debug information expect the descriptors for program
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]290 objects to start in a canonical format, but the descriptors can include
291 additional information appended at the end that is source-language
292 specific. All LLVM debugging information is versioned, allowing backwards
293 compatibility in the case that the core structures need to change in some
294 way. Also, all debugging information objects start with a tag to indicate
295 what type of object it is. The source-language is allowed to define its own
296 objects, by using unreserved tag numbers. We recommend using with tags in
Benjamin Kramer8040cd32009-10-12 14:46:08 +0000[diff] [blame]297 the range 0x1000 through 0x2000 (there is a defined enum DW_TAG_user_base =
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]298 0x1000.)</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]299
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]300<p>The fields of debug descriptors used internally by LLVM
Nick Lewycky655fd032010-03-31 07:50:17 +0000[diff] [blame]301 are restricted to only the simple data types <tt>i32</tt>, <tt>i1</tt>,
302 <tt>float</tt>, <tt>double</tt>, <tt>mdstring</tt> and <tt>mdnode</tt>. </p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]303
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]304<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]305<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]306!1 = metadata !{
Nick Lewycky655fd032010-03-31 07:50:17 +0000[diff] [blame]307 i32, ;; A tag
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]308 ...
309}
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]310</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]311</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]312
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]313<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
Nick Lewycky655fd032010-03-31 07:50:17 +0000[diff] [blame]314 <tt>i32</tt> containing a tag value identifying the content of the
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]315 descriptor. The remaining fields are specific to the descriptor. The values
316 of tags are loosely bound to the tag values of DWARF information entries.
317 However, that does not restrict the use of the information supplied to DWARF
318 targets. To facilitate versioning of debug information, the tag is augmented
Nick Lewyckyf3379da2011-07-25 21:13:23 +0000[diff] [blame]319 with the current debug version (LLVMDebugVersion = 8 &lt;&lt; 16 or
320 0x80000 or 524288.)</a></p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]321
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]322<p>The details of the various descriptors follow.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]323
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]324<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]325<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]326 <a name="format_compile_units">Compile unit descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]327</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]328
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]329<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]330
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]331<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]332<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]333!0 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]334 i32, ;; Tag = 17 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]335 ;; (DW_TAG_compile_unit)
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]336 i32, ;; Unused field.
337 i32, ;; DWARF language identifier (ex. DW_LANG_C89)
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]338 metadata, ;; Source file name
339 metadata, ;; Source file directory (includes trailing slash)
340 metadata ;; Producer (ex. "4.0.1 LLVM (LLVM research group)")
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]341 i1, ;; True if this is a main compile unit.
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]342 i1, ;; True if this is optimized.
343 metadata, ;; Flags
344 i32 ;; Runtime version
Devang Patel9b4a2ac2011-09-09 17:07:15 +0000[diff] [blame]345 metadata ;; List of enums types
346 metadata ;; List of retained types
347 metadata ;; List of subprograms
348 metadata ;; List of global variables
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]349}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]350</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]351</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]352
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]353<p>These descriptors contain a source language ID for the file (we use the DWARF
354 3.0 ID numbers, such as <tt>DW_LANG_C89</tt>, <tt>DW_LANG_C_plus_plus</tt>,
355 <tt>DW_LANG_Cobol74</tt>, etc), three strings describing the filename,
356 working directory of the compiler, and an identifier string for the compiler
357 that produced it.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]358
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]359<p>Compile unit descriptors provide the root context for objects declared in a
Devang Patel464f4ef2011-05-03 16:18:28 +0000[diff] [blame]360 specific compilation unit. File descriptors are defined using this context.
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]361 These descriptors are collected by a named metadata
Devang Patel9b4a2ac2011-09-09 17:07:15 +0000[diff] [blame]362 <tt>!llvm.dbg.cu</tt>. Compile unit descriptor keeps track of subprograms,
363 global variables and type information.
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]364
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]365</div>
366
367<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]368<h4>
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]369 <a name="format_files">File descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]370</h4>
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]371
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]372<div>
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]373
374<div class="doc_code">
375<pre>
376!0 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]377 i32, ;; Tag = 41 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]378 ;; (DW_TAG_file_type)
379 metadata, ;; Source file name
380 metadata, ;; Source file directory (includes trailing slash)
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]381 metadata ;; Unused
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]382}
383</pre>
384</div>
385
John Criswellb34500f2010-03-17 15:01:50 +0000[diff] [blame]386<p>These descriptors contain information for a file. Global variables and top
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]387 level functions would be defined using this context.k File descriptors also
388 provide context for source line correspondence. </p>
389
390<p>Each input file is encoded as a separate file descriptor in LLVM debugging
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]391 information output. </p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]392
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]393</div>
394
395<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]396<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]397 <a name="format_global_variables">Global variable descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]398</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]399
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]400<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]401
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]402<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]403<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]404!1 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]405 i32, ;; Tag = 52 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]406 ;; (DW_TAG_variable)
407 i32, ;; Unused field.
408 metadata, ;; Reference to context descriptor
409 metadata, ;; Name
410 metadata, ;; Display name (fully qualified C++ name)
411 metadata, ;; MIPS linkage name (for C++)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]412 metadata, ;; Reference to file where defined
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]413 i32, ;; Line number where defined
414 metadata, ;; Reference to type descriptor
415 i1, ;; True if the global is local to compile unit (static)
416 i1, ;; True if the global is defined in the compile unit (not extern)
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000[diff] [blame]417 {}* ;; Reference to the global variable
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]418}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]419</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]420</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]421
422<p>These descriptors provide debug information about globals variables. The
Devang Patelda6eed32011-03-29 17:27:08 +0000[diff] [blame]423provide details such as name, type and where the variable is defined. All
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]424global variables are collected inside the named metadata
425<tt>!llvm.dbg.cu</tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]426
427</div>
428
429<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]430<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]431 <a name="format_subprograms">Subprogram descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]432</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]433
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]434<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]435
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]436<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]437<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]438!2 = metadata !{
439 i32, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
440 ;; (DW_TAG_subprogram)
441 i32, ;; Unused field.
442 metadata, ;; Reference to context descriptor
443 metadata, ;; Name
444 metadata, ;; Display name (fully qualified C++ name)
445 metadata, ;; MIPS linkage name (for C++)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]446 metadata, ;; Reference to file where defined
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]447 i32, ;; Line number where defined
448 metadata, ;; Reference to type descriptor
449 i1, ;; True if the global is local to compile unit (static)
Devang Patel5e06bb82011-04-22 23:10:17 +0000[diff] [blame]450 i1, ;; True if the global is defined in the compile unit (not extern)
Eric Christopher6126a1e2012-04-03 00:43:49 +0000[diff] [blame]451 i32, ;; Line number where the scope of the subprogram begins
Devang Patel5e06bb82011-04-22 23:10:17 +0000[diff] [blame]452 i32, ;; Virtuality, e.g. dwarf::DW_VIRTUALITY__virtual
453 i32, ;; Index into a virtual function
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]454 metadata, ;; indicates which base type contains the vtable pointer for the
Devang Patel80ecc152010-06-04 22:49:55 +0000[diff] [blame]455 ;; derived class
Devang Patel473f95f2011-12-16 17:50:04 +0000[diff] [blame]456 i32, ;; Flags - Artifical, Private, Protected, Explicit, Prototyped.
Devang Patel5e06bb82011-04-22 23:10:17 +0000[diff] [blame]457 i1, ;; isOptimized
458 Function *,;; Pointer to LLVM function
459 metadata, ;; Lists function template parameters
460 metadata ;; Function declaration descriptor
Devang Patel93d39be2011-08-19 23:28:12 +0000[diff] [blame]461 metadata ;; List of function variables
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]462}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]463</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]464</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]465
466<p>These descriptors provide debug information about functions, methods and
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]467 subprograms. They provide details such as name, return types and the source
Devang Patelda6eed32011-03-29 17:27:08 +0000[diff] [blame]468 location where the subprogram is defined.
Devang Patelda6eed32011-03-29 17:27:08 +0000[diff] [blame]469</p>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]470
471</div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]472
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]473<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]474<h4>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]475 <a name="format_blocks">Block descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]476</h4>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]477
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]478<div>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]479
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]480<div class="doc_code">
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]481<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]482!3 = metadata !{
Devang Patelc79dda22010-10-04 16:51:59 +0000[diff] [blame]483 i32, ;; Tag = 11 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
Devang Patel7f271fc2010-10-01 22:45:00 +0000[diff] [blame]484 metadata,;; Reference to context descriptor
485 i32, ;; Line number
Devang Patel90d81f12011-03-08 16:25:29 +0000[diff] [blame]486 i32, ;; Column number
487 metadata,;; Reference to source file
488 i32 ;; Unique ID to identify blocks from a template function
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]489}
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]490</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]491</div>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]492
Eric Christopher6618a242011-10-11 22:59:11 +0000[diff] [blame]493<p>This descriptor provides debug information about nested blocks within a
Devang Patel7f271fc2010-10-01 22:45:00 +0000[diff] [blame]494 subprogram. The line number and column numbers are used to dinstinguish
495 two lexical blocks at same depth. </p>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]496
Eric Christopher6618a242011-10-11 22:59:11 +0000[diff] [blame]497<div class="doc_code">
498<pre>
499!3 = metadata !{
500 i32, ;; Tag = 11 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
501 metadata ;; Reference to the scope we're annotating with a file change
502 metadata,;; Reference to the file the scope is enclosed in.
503}
504</pre>
505</div>
506
507<p>This descriptor provides a wrapper around a lexical scope to handle file
508 changes in the middle of a lexical block.</p>
509
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]510</div>
511
512<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]513<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]514 <a name="format_basic_type">Basic type descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]515</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]516
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]517<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]518
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]519<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]520<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]521!4 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]522 i32, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]523 ;; (DW_TAG_base_type)
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]524 metadata, ;; Reference to context
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]525 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]526 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]527 i32, ;; Line number where defined (may be 0)
528 i64, ;; Size in bits
529 i64, ;; Alignment in bits
530 i64, ;; Offset in bits
531 i32, ;; Flags
532 i32 ;; DWARF type encoding
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]533}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]534</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]535</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]536
537<p>These descriptors define primitive types used in the code. Example int, bool
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]538 and float. The context provides the scope of the type, which is usually the
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]539 top level. Since basic types are not usually user defined the context
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]540 and line number can be left as NULL and 0. The size, alignment and offset
541 are expressed in bits and can be 64 bit values. The alignment is used to
542 round the offset when embedded in a
543 <a href="#format_composite_type">composite type</a> (example to keep float
544 doubles on 64 bit boundaries.) The offset is the bit offset if embedded in
545 a <a href="#format_composite_type">composite type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]546
547<p>The type encoding provides the details of the type. The values are typically
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]548 one of the following:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]549
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]550<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]551<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]552DW_ATE_address = 1
553DW_ATE_boolean = 2
554DW_ATE_float = 4
555DW_ATE_signed = 5
556DW_ATE_signed_char = 6
557DW_ATE_unsigned = 7
558DW_ATE_unsigned_char = 8
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]559</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]560</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]561
562</div>
563
564<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]565<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]566 <a name="format_derived_type">Derived type descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]567</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]568
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]569<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]570
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]571<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]572<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]573!5 = metadata !{
574 i32, ;; Tag (see below)
575 metadata, ;; Reference to context
576 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]577 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]578 i32, ;; Line number where defined (may be 0)
Devang Patel0ffd10b2010-10-01 19:19:30 +0000[diff] [blame]579 i64, ;; Size in bits
580 i64, ;; Alignment in bits
581 i64, ;; Offset in bits
Eric Christopher402e12a2011-12-16 23:42:33 +0000[diff] [blame]582 i32, ;; Flags to encode attributes, e.g. private
Devang Patele9db5e22011-04-16 00:11:51 +0000[diff] [blame]583 metadata, ;; Reference to type derived from
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]584 metadata, ;; (optional) Name of the Objective C property associated with
585 ;; Objective-C an ivar
Devang Patele9db5e22011-04-16 00:11:51 +0000[diff] [blame]586 metadata, ;; (optional) Name of the Objective C property getter selector.
587 metadata, ;; (optional) Name of the Objective C property setter selector.
588 i32 ;; (optional) Objective C property attributes.
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]589}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]590</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]591</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]592
593<p>These descriptors are used to define types derived from other types. The
594value of the tag varies depending on the meaning. The following are possible
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]595tag values:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]596
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]597<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]598<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]599DW_TAG_formal_parameter = 5
600DW_TAG_member = 13
601DW_TAG_pointer_type = 15
602DW_TAG_reference_type = 16
603DW_TAG_typedef = 22
604DW_TAG_const_type = 38
605DW_TAG_volatile_type = 53
606DW_TAG_restrict_type = 55
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]607</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]608</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]609
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]610<p><tt>DW_TAG_member</tt> is used to define a member of
611 a <a href="#format_composite_type">composite type</a>
612 or <a href="#format_subprograms">subprogram</a>. The type of the member is
613 the <a href="#format_derived_type">derived
614 type</a>. <tt>DW_TAG_formal_parameter</tt> is used to define a member which
615 is a formal argument of a subprogram.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]616
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]617<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]618
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]619<p><tt>DW_TAG_pointer_type</tt>, <tt>DW_TAG_reference_type</tt>,
620 <tt>DW_TAG_const_type</tt>, <tt>DW_TAG_volatile_type</tt> and
Eric Christopheradfc1ef2011-12-16 23:42:35 +0000[diff] [blame]621 <tt>DW_TAG_restrict_type</tt> are used to qualify
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]622 the <a href="#format_derived_type">derived type</a>. </p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]623
624<p><a href="#format_derived_type">Derived type</a> location can be determined
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]625 from the context and line number. The size, alignment and offset are
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]626 expressed in bits and can be 64 bit values. The alignment is used to round
627 the offset when embedded in a <a href="#format_composite_type">composite
628 type</a> (example to keep float doubles on 64 bit boundaries.) The offset is
629 the bit offset if embedded in a <a href="#format_composite_type">composite
630 type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]631
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]632<p>Note that the <tt>void *</tt> type is expressed as a type derived from NULL.
633</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]634
635</div>
636
637<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]638<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]639 <a name="format_composite_type">Composite type descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]640</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]641
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]642<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]643
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]644<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]645<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]646!6 = metadata !{
647 i32, ;; Tag (see below)
648 metadata, ;; Reference to context
649 metadata, ;; Name (may be "" for anonymous types)
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]650 metadata, ;; Reference to file where defined (may be NULL)
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]651 i32, ;; Line number where defined (may be 0)
652 i64, ;; Size in bits
653 i64, ;; Alignment in bits
654 i64, ;; Offset in bits
655 i32, ;; Flags
656 metadata, ;; Reference to type derived from
657 metadata, ;; Reference to array of member descriptors
658 i32 ;; Runtime languages
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]659}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]660</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]661</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]662
663<p>These descriptors are used to define types that are composed of 0 or more
664elements. The value of the tag varies depending on the meaning. The following
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]665are possible tag values:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]666
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]667<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]668<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]669DW_TAG_array_type = 1
670DW_TAG_enumeration_type = 4
671DW_TAG_structure_type = 19
672DW_TAG_union_type = 23
673DW_TAG_vector_type = 259
Bruno Cardoso Lopesd80ddc02009-05-29 17:08:57 +0000[diff] [blame]674DW_TAG_subroutine_type = 21
675DW_TAG_inheritance = 28
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]676</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]677</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]678
Jim Laskeyf8a01a92006-06-15 20:51:43 +0000[diff] [blame]679<p>The vector flag indicates that an array type is a native packed vector.</p>
680
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]681<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]682 (tag = <tt>DW_TAG_vector_type</tt>) are <a href="#format_subrange">subrange
683 descriptors</a>, each representing the range of subscripts at that level of
684 indexing.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]685
686<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]687 <a href="#format_enumeration">enumerator descriptors</a>, each representing
Devang Patelda6eed32011-03-29 17:27:08 +0000[diff] [blame]688 the definition of enumeration value for the set. All enumeration type
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]689 descriptors are collected inside the named metadata
690 <tt>!llvm.dbg.cu</tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]691
692<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]693 = <tt>DW_TAG_union_type</tt>) types are any one of
694 the <a href="#format_basic_type">basic</a>,
695 <a href="#format_derived_type">derived</a>
696 or <a href="#format_composite_type">composite</a> type descriptors, each
697 representing a field member of the structure or union.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]698
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]699<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]700 provide information about base classes, static members and member
701 functions. If a member is a <a href="#format_derived_type">derived type
702 descriptor</a> and has a tag of <tt>DW_TAG_inheritance</tt>, then the type
703 represents a base class. If the member of is
704 a <a href="#format_global_variables">global variable descriptor</a> then it
705 represents a static member. And, if the member is
706 a <a href="#format_subprograms">subprogram descriptor</a> then it represents
707 a member function. For static members and member
708 functions, <tt>getName()</tt> returns the members link or the C++ mangled
709 name. <tt>getDisplayName()</tt> the simplied version of the name.</p>
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]710
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]711<p>The first member of subroutine (tag = <tt>DW_TAG_subroutine_type</tt>) type
712 elements is the return type for the subroutine. The remaining elements are
713 the formal arguments to the subroutine.</p>
Jim Laskey094ee722006-06-20 21:13:20 +0000[diff] [blame]714
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]715<p><a href="#format_composite_type">Composite type</a> location can be
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]716 determined from the context and line number. The size, alignment and
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]717 offset are expressed in bits and can be 64 bit values. The alignment is used
718 to round the offset when embedded in
719 a <a href="#format_composite_type">composite type</a> (as an example, to keep
720 float doubles on 64 bit boundaries.) The offset is the bit offset if embedded
721 in a <a href="#format_composite_type">composite type</a>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]722
723</div>
724
725<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]726<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]727 <a name="format_subrange">Subrange descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]728</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]729
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]730<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]731
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]732<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]733<pre>
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]734!42 = metadata !{
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]735 i32, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
736 i64, ;; Low value
737 i64 ;; High value
738}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]739</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]740</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]741
742<p>These descriptors are used to define ranges of array subscripts for an array
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]743 <a href="#format_composite_type">composite type</a>. The low value defines
744 the lower bounds typically zero for C/C++. The high value is the upper
745 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]746 > high the array bounds are not included in generated debugging information.
747</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]748
749</div>
750
751<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]752<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]753 <a name="format_enumeration">Enumerator descriptors</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]754</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]755
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]756<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]757
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]758<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]759<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]760!6 = metadata !{
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]761 i32, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]762 ;; (DW_TAG_enumerator)
763 metadata, ;; Name
764 i64 ;; Value
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]765}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]766</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]767</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]768
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]769<p>These descriptors are used to define members of an
770 enumeration <a href="#format_composite_type">composite type</a>, it
771 associates the name to the value.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]772
773</div>
774
775<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]776<h4>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]777 <a name="format_variables">Local variables</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]778</h4>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]779
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]780<div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]781
782<div class="doc_code">
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]783<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]784!7 = metadata !{
785 i32, ;; Tag (see below)
786 metadata, ;; Context
787 metadata, ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]788 metadata, ;; Reference to file where defined
Devang Patela83688f2011-03-08 16:29:40 +0000[diff] [blame]789 i32, ;; 24 bit - Line number where defined
790 ;; 8 bit - Argument number. 1 indicates 1st argument.
Devang Patel0a2a3062011-07-27 18:14:50 +0000[diff] [blame]791 metadata, ;; Type descriptor
792 i32, ;; flags
793 metadata ;; (optional) Reference to inline location
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]794}
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]795</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]796</div>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]797
798<p>These descriptors are used to define variables local to a sub program. The
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]799 value of the tag depends on the usage of the variable:</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]800
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]801<div class="doc_code">
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]802<pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]803DW_TAG_auto_variable = 256
804DW_TAG_arg_variable = 257
805DW_TAG_return_variable = 258
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]806</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]807</div>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]808
809<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]810 argument variable is any variable that appears as a formal argument to the
811 function. A return variable is used to track the result of a function and
812 has no source correspondent.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]813
Jim Laskey2d395d92006-03-24 09:20:27 +0000[diff] [blame]814<p>The context is either the subprogram or block where the variable is defined.
Devang Patel94c7ddb2011-08-16 22:09:43 +0000[diff] [blame]815 Name the source variable name. Context and line indicate where the
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]816 variable was defined. Type descriptor defines the declared type of the
817 variable.</p>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]818
819</div>
820
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]821</div>
822
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]823<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]824<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]825 <a name="format_common_intrinsics">Debugger intrinsic functions</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]826</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]827
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]828<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]829
830<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]831 provide debug information at various points in generated code.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]832
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]833<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]834<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]835 <a name="format_common_declare">llvm.dbg.declare</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]836</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]837
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]838<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]839<pre>
Devang Patel4c7c0c62010-10-01 19:22:16 +0000[diff] [blame]840 void %<a href="#format_common_declare">llvm.dbg.declare</a>(metadata, metadata)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]841</pre>
842
Chad Rosier5bfd9692012-02-18 01:38:41 +0000[diff] [blame]843<p>This intrinsic provides information about a local element (e.g., variable). The
844 first argument is metadata holding the alloca for the variable. The
845 second argument is metadata containing a description of the variable.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]846</div>
847
848<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]849<h4>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]850 <a name="format_common_value">llvm.dbg.value</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]851</h4>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]852
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]853<div>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]854<pre>
Dan Gohman3dfb3cf2010-05-28 17:07:41 +0000[diff] [blame]855 void %<a href="#format_common_value">llvm.dbg.value</a>(metadata, i64, metadata)
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]856</pre>
857
858<p>This intrinsic provides information when a user source variable is set to a
859 new value. The first argument is the new value (wrapped as metadata). The
860 second argument is the offset in the user source variable where the new value
Chad Rosier5bfd9692012-02-18 01:38:41 +0000[diff] [blame]861 is written. The third argument is metadata containing a description of the
862 user source variable.</p>
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]863</div>
864
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]865</div>
866
Victor Hernandez67a1a542010-01-11 22:53:48 +0000[diff] [blame]867<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]868<h3>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]869 <a name="format_common_lifetime">Object lifetimes and scoping</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]870</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]871
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]872<div>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]873<p>In many languages, the local variables in functions can have their lifetimes
874 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]875 for example, variables are only live (readable and writable) within the
876 source block that they are defined in. In functional languages, values are
877 only readable after they have been defined. Though this is a very obvious
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]878 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]879 scoping in this sense, and does not want to be tied to a language's scoping
880 rules.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]881
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]882<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]883 llvm instructions to encode line number and scoping information. Consider
884 the following C fragment, for example:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]885
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]886<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]887<pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8881. void foo() {
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]8892. int X = 21;
8903. int Y = 22;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8914. {
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]8925. int Z = 23;
8936. Z = X;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8947. }
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]8958. X = Y;
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8969. }
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]897</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]898</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]899
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]900<p>Compiled to LLVM, this function would be represented like this:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]901
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]902<div class="doc_code">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]903<pre>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]904define void @foo() nounwind ssp {
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]905entry:
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]906 %X = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
907 %Y = alloca i32, align 4 ; &lt;i32*&gt; [#uses=4]
908 %Z = alloca i32, align 4 ; &lt;i32*&gt; [#uses=3]
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000[diff] [blame]909 %0 = bitcast i32* %X to {}* ; &lt;{}*&gt; [#uses=1]
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]910 call void @llvm.dbg.declare(metadata !{i32 * %X}, metadata !0), !dbg !7
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]911 store i32 21, i32* %X, !dbg !8
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000[diff] [blame]912 %1 = bitcast i32* %Y to {}* ; &lt;{}*&gt; [#uses=1]
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]913 call void @llvm.dbg.declare(metadata !{i32 * %Y}, metadata !9), !dbg !10
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]914 store i32 22, i32* %Y, !dbg !11
Dan Gohmanfe47aae2010-05-28 17:13:49 +0000[diff] [blame]915 %2 = bitcast i32* %Z to {}* ; &lt;{}*&gt; [#uses=1]
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]916 call void @llvm.dbg.declare(metadata !{i32 * %Z}, metadata !12), !dbg !14
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]917 store i32 23, i32* %Z, !dbg !15
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]918 %tmp = load i32* %X, !dbg !16 ; &lt;i32&gt; [#uses=1]
919 %tmp1 = load i32* %Y, !dbg !16 ; &lt;i32&gt; [#uses=1]
920 %add = add nsw i32 %tmp, %tmp1, !dbg !16 ; &lt;i32&gt; [#uses=1]
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]921 store i32 %add, i32* %Z, !dbg !16
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]922 %tmp2 = load i32* %Y, !dbg !17 ; &lt;i32&gt; [#uses=1]
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]923 store i32 %tmp2, i32* %X, !dbg !17
924 ret void, !dbg !18
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]925}
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]926
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]927declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]928
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]929!0 = metadata !{i32 459008, metadata !1, metadata !"X",
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]930 metadata !3, i32 2, metadata !6}; [ DW_TAG_auto_variable ]
931!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]932!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo", metadata !"foo",
933 metadata !"foo", metadata !3, i32 1, metadata !4,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]934 i1 false, i1 true}; [DW_TAG_subprogram ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]935!3 = metadata !{i32 458769, i32 0, i32 12, metadata !"foo.c",
936 metadata !"/private/tmp", metadata !"clang 1.1", i1 true,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]937 i1 false, metadata !"", i32 0}; [DW_TAG_compile_unit ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]938!4 = metadata !{i32 458773, metadata !3, metadata !"", null, i32 0, i64 0, i64 0,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]939 i64 0, i32 0, null, metadata !5, i32 0}; [DW_TAG_subroutine_type ]
940!5 = metadata !{null}
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]941!6 = metadata !{i32 458788, metadata !3, metadata !"int", metadata !3, i32 0,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]942 i64 32, i64 32, i64 0, i32 0, i32 5}; [DW_TAG_base_type ]
943!7 = metadata !{i32 2, i32 7, metadata !1, null}
944!8 = metadata !{i32 2, i32 3, metadata !1, null}
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]945!9 = metadata !{i32 459008, metadata !1, metadata !"Y", metadata !3, i32 3,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]946 metadata !6}; [ DW_TAG_auto_variable ]
947!10 = metadata !{i32 3, i32 7, metadata !1, null}
948!11 = metadata !{i32 3, i32 3, metadata !1, null}
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]949!12 = metadata !{i32 459008, metadata !13, metadata !"Z", metadata !3, i32 5,
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]950 metadata !6}; [ DW_TAG_auto_variable ]
951!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
952!14 = metadata !{i32 5, i32 9, metadata !13, null}
953!15 = metadata !{i32 5, i32 5, metadata !13, null}
954!16 = metadata !{i32 6, i32 5, metadata !13, null}
955!17 = metadata !{i32 8, i32 3, metadata !1, null}
956!18 = metadata !{i32 9, i32 1, metadata !2, null}
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]957</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]958</div>
959
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]960<p>This example illustrates a few important details about LLVM debugging
961 information. In particular, it shows how the <tt>llvm.dbg.declare</tt>
962 intrinsic and location information, which are attached to an instruction,
963 are applied together to allow a debugger to analyze the relationship between
964 statements, variable definitions, and the code used to implement the
965 function.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]966
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]967<div class="doc_code">
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]968<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]969call void @llvm.dbg.declare(metadata, metadata !0), !dbg !7
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]970</pre>
971</div>
972
973<p>The first intrinsic
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]974 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]975 encodes debugging information for the variable <tt>X</tt>. The metadata
976 <tt>!dbg !7</tt> attached to the intrinsic provides scope information for the
977 variable <tt>X</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]978
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]979<div class="doc_code">
980<pre>
981!7 = metadata !{i32 2, i32 7, metadata !1, null}
982!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]983!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo",
984 metadata !"foo", metadata !"foo", metadata !3, i32 1,
985 metadata !4, i1 false, i1 true}; [DW_TAG_subprogram ]
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]986</pre>
987</div>
988
989<p>Here <tt>!7</tt> is metadata providing location information. It has four
990 fields: line number, column number, scope, and original scope. The original
991 scope represents inline location if this instruction is inlined inside a
992 caller, and is null otherwise. In this example, scope is encoded by
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]993 <tt>!1</tt>. <tt>!1</tt> represents a lexical block inside the scope
994 <tt>!2</tt>, where <tt>!2</tt> is a
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]995 <a href="#format_subprograms">subprogram descriptor</a>. This way the
996 location information attached to the intrinsics indicates that the
997 variable <tt>X</tt> is declared at line number 2 at a function level scope in
998 function <tt>foo</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]999
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]1000<p>Now lets take another example.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1001
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1002<div class="doc_code">
Bill Wendling02216ff2009-12-01 00:59:58 +0000[diff] [blame]1003<pre>
Devang Patel37280782011-02-03 00:22:17 +0000[diff] [blame]1004call void @llvm.dbg.declare(metadata, metadata !12), !dbg !14
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1005</pre>
1006</div>
1007
1008<p>The second intrinsic
Devang Patel744950d2009-11-25 23:28:01 +0000[diff] [blame]1009 <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1010 encodes debugging information for variable <tt>Z</tt>. The metadata
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1011 <tt>!dbg !14</tt> attached to the intrinsic provides scope information for
1012 the variable <tt>Z</tt>.</p>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1013
Bill Wendlingcf493b82009-12-01 00:53:11 +0000[diff] [blame]1014<div class="doc_code">
1015<pre>
1016!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
1017!14 = metadata !{i32 5, i32 9, metadata !13, null}
1018</pre>
1019</div>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1020
John Criswellb34500f2010-03-17 15:01:50 +0000[diff] [blame]1021<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]1022 column number 9 inside of lexical scope <tt>!13</tt>. The lexical scope
1023 itself resides inside of lexical scope <tt>!1</tt> described above.</p>
1024
1025<p>The scope information attached with each instruction provides a
1026 straightforward way to find instructions covered by a scope.</p>
1027
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1028</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1029
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1030</div>
1031
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1032<!-- *********************************************************************** -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1033<h2>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1034 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1035</h2>
Misha Brukman94218a72004-12-09 20:27:37 +0000[diff] [blame]1036<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1037
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1038<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1039
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1040<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]1041 that is effectively identical
1042 to <a href="http://www.eagercon.com/dwarf/dwarf3std.htm">DWARF 3.0</a> in
1043 terms of information content. This allows code generators to trivially
1044 support native debuggers by generating standard dwarf information, and
1045 contains enough information for non-dwarf targets to translate it as
1046 needed.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1047
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1048<p>This section describes the forms used to represent C and C++ programs. Other
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1049 languages could pattern themselves after this (which itself is tuned to
1050 representing programs in the same way that DWARF 3 does), or they could
1051 choose to provide completely different forms if they don't fit into the DWARF
1052 model. As support for debugging information gets added to the various LLVM
1053 source-language front-ends, the information used should be documented
1054 here.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1055
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1056<p>The following sections provide examples of various C/C++ constructs and the
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1057 debug information that would best describe those constructs.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1058
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1059<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1060<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1061 <a name="ccxx_compile_units">C/C++ source file information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1062</h3>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1063
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1064<div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1065
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1066<p>Given the source files <tt>MySource.cpp</tt> and <tt>MyHeader.h</tt> located
1067 in the directory <tt>/Users/mine/sources</tt>, the following code:</p>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1068
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1069<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1070<pre>
1071#include "MyHeader.h"
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1072
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1073int main(int argc, char *argv[]) {
1074 return 0;
1075}
1076</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1077</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1078
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1079<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1080
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1081<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1082<pre>
1083...
1084;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1085;; Define the compile unit for the main source file "/Users/mine/sources/MySource.cpp".
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1086;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1087!2 = metadata !{
1088 i32 524305, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1089 i32 0, ;; Unused
1090 i32 4, ;; Language Id
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1091 metadata !"MySource.cpp",
1092 metadata !"/Users/mine/sources",
1093 metadata !"4.2.1 (Based on Apple Inc. build 5649) (LLVM build 00)",
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1094 i1 true, ;; Main Compile Unit
1095 i1 false, ;; Optimized compile unit
1096 metadata !"", ;; Compiler flags
1097 i32 0} ;; Runtime version
1098
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1099;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1100;; Define the file for the file "/Users/mine/sources/MySource.cpp".
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1101;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1102!1 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1103 i32 524329, ;; Tag
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1104 metadata !"MySource.cpp",
1105 metadata !"/Users/mine/sources",
Devang Patel9fea9c22010-07-13 16:53:20 +0000[diff] [blame]1106 metadata !2 ;; Compile unit
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1107}
1108
1109;;
1110;; Define the file for the file "/Users/mine/sources/Myheader.h"
1111;;
1112!3 = metadata !{
1113 i32 524329, ;; Tag
1114 metadata !"Myheader.h"
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1115 metadata !"/Users/mine/sources",
Devang Patel9fea9c22010-07-13 16:53:20 +0000[diff] [blame]1116 metadata !2 ;; Compile unit
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1117}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1118
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1119...
1120</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1121</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1122
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1123<p>llvm::Instruction provides easy access to metadata attached with an
Devang Pateld98ec5f2010-03-26 19:08:36 +0000[diff] [blame]1124instruction. One can extract line number information encoded in LLVM IR
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1125using <tt>Instruction::getMetadata()</tt> and
Devang Pateld98ec5f2010-03-26 19:08:36 +0000[diff] [blame]1126<tt>DILocation::getLineNumber()</tt>.
1127<pre>
1128 if (MDNode *N = I->getMetadata("dbg")) { // Here I is an LLVM instruction
1129 DILocation Loc(N); // DILocation is in DebugInfo.h
1130 unsigned Line = Loc.getLineNumber();
1131 StringRef File = Loc.getFilename();
1132 StringRef Dir = Loc.getDirectory();
1133 }
1134</pre>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1135</div>
1136
1137<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1138<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1139 <a name="ccxx_global_variable">C/C++ global variable information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1140</h3>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1141
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1142<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1143
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1144<p>Given an integer global variable declared as follows:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1145
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1146<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1147<pre>
1148int MyGlobal = 100;
1149</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1150</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1151
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1152<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1153
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1154<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1155<pre>
1156;;
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1157;; Define the global itself.
1158;;
1159%MyGlobal = global int 100
1160...
1161;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1162;; List of debug info of globals
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1163;;
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]1164!llvm.dbg.cu = !{!0}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1165
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]1166;; Define the compile unit.
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1167!0 = metadata !{
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]1168 i32 786449, ;; Tag
1169 i32 0, ;; Context
1170 i32 4, ;; Language
1171 metadata !"foo.cpp", ;; File
1172 metadata !"/Volumes/Data/tmp", ;; Directory
1173 metadata !"clang version 3.1 ", ;; Producer
1174 i1 true, ;; Deprecated field
1175 i1 false, ;; "isOptimized"?
1176 metadata !"", ;; Flags
1177 i32 0, ;; Runtime Version
1178 metadata !1, ;; Enum Types
1179 metadata !1, ;; Retained Types
1180 metadata !1, ;; Subprograms
1181 metadata !3 ;; Global Variables
1182} ; [ DW_TAG_compile_unit ]
1183
1184;; The Array of Global Variables
1185!3 = metadata !{
1186 metadata !4
1187}
1188
1189!4 = metadata !{
1190 metadata !5
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1191}
1192
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1193;;
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]1194;; Define the global variable itself.
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1195;;
Eric Christopher4787cc42012-03-26 01:56:34 +0000[diff] [blame]1196!5 = metadata !{
1197 i32 786484, ;; Tag
1198 i32 0, ;; Unused
1199 null, ;; Unused
1200 metadata !"MyGlobal", ;; Name
1201 metadata !"MyGlobal", ;; Display Name
1202 metadata !"", ;; Linkage Name
1203 metadata !6, ;; File
1204 i32 1, ;; Line
1205 metadata !7, ;; Type
1206 i32 0, ;; IsLocalToUnit
1207 i32 1, ;; IsDefinition
1208 i32* @MyGlobal ;; LLVM-IR Value
1209} ; [ DW_TAG_variable ]
1210
1211;;
1212;; Define the file
1213;;
1214!6 = metadata !{
1215 i32 786473, ;; Tag
1216 metadata !"foo.cpp", ;; File
1217 metadata !"/Volumes/Data/tmp", ;; Directory
1218 null ;; Unused
1219} ; [ DW_TAG_file_type ]
1220
1221;;
1222;; Define the type
1223;;
1224!7 = metadata !{
1225 i32 786468, ;; Tag
1226 null, ;; Unused
1227 metadata !"int", ;; Name
1228 null, ;; Unused
1229 i32 0, ;; Line
1230 i64 32, ;; Size in Bits
1231 i64 32, ;; Align in Bits
1232 i64 0, ;; Offset
1233 i32 0, ;; Flags
1234 i32 5 ;; Encoding
1235} ; [ DW_TAG_base_type ]
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1236
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1237</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1238</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1239
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1240</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1241
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1242<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1243<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1244 <a name="ccxx_subprogram">C/C++ function information</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1245</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1246
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1247<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1248
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1249<p>Given a function declared as follows:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1250
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1251<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1252<pre>
1253int main(int argc, char *argv[]) {
1254 return 0;
1255}
1256</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1257</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1258
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1259<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1260
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1261<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1262<pre>
1263;;
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1264;; Define the anchor for subprograms. Note that the second field of the
1265;; anchor is 46, which is the same as the tag for subprograms
1266;; (46 = DW_TAG_subprogram.)
1267;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1268!6 = metadata !{
1269 i32 524334, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1270 i32 0, ;; Unused
1271 metadata !1, ;; Context
1272 metadata !"main", ;; Name
1273 metadata !"main", ;; Display name
1274 metadata !"main", ;; Linkage name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1275 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1276 i32 1, ;; Line number
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1277 metadata !4, ;; Type
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1278 i1 false, ;; Is local
Devang Patelda194752011-04-05 22:52:06 +0000[diff] [blame]1279 i1 true, ;; Is definition
1280 i32 0, ;; Virtuality attribute, e.g. pure virtual function
1281 i32 0, ;; Index into virtual table for C++ methods
1282 i32 0, ;; Type that holds virtual table.
1283 i32 0, ;; Flags
1284 i1 false, ;; True if this function is optimized
1285 Function *, ;; Pointer to llvm::Function
1286 null ;; Function template parameters
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1287}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1288;;
1289;; Define the subprogram itself.
1290;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1291define i32 @main(i32 %argc, i8** %argv) {
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1292...
1293}
1294</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1295</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1296
1297</div>
1298
1299<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1300<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1301 <a name="ccxx_basic_types">C/C++ basic types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1302</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1303
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1304<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1305
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1306<p>The following are the basic type descriptors for C/C++ core types:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1307
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1308<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1309<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1310 <a name="ccxx_basic_type_bool">bool</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1311</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1312
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1313<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1314
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1315<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1316<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1317!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1318 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1319 metadata !1, ;; Context
1320 metadata !"bool", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1321 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1322 i32 0, ;; Line number
1323 i64 8, ;; Size in Bits
1324 i64 8, ;; Align in Bits
1325 i64 0, ;; Offset in Bits
1326 i32 0, ;; Flags
1327 i32 2 ;; Encoding
1328}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1329</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1330</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1331
1332</div>
1333
1334<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1335<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1336 <a name="ccxx_basic_char">char</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1337</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1338
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1339<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1340
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1341<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1342<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1343!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1344 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1345 metadata !1, ;; Context
1346 metadata !"char", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1347 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1348 i32 0, ;; Line number
1349 i64 8, ;; Size in Bits
1350 i64 8, ;; Align in Bits
1351 i64 0, ;; Offset in Bits
1352 i32 0, ;; Flags
1353 i32 6 ;; Encoding
1354}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1355</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1356</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1357
1358</div>
1359
1360<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1361<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1362 <a name="ccxx_basic_unsigned_char">unsigned char</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1363</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1364
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1365<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1366
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1367<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1368<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1369!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1370 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1371 metadata !1, ;; Context
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1372 metadata !"unsigned char",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1373 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1374 i32 0, ;; Line number
1375 i64 8, ;; Size in Bits
1376 i64 8, ;; Align in Bits
1377 i64 0, ;; Offset in Bits
1378 i32 0, ;; Flags
1379 i32 8 ;; Encoding
1380}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1381</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1382</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1383
1384</div>
1385
1386<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1387<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1388 <a name="ccxx_basic_short">short</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1389</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1390
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1391<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1392
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1393<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1394<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1395!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1396 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1397 metadata !1, ;; Context
1398 metadata !"short int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1399 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1400 i32 0, ;; Line number
1401 i64 16, ;; Size in Bits
1402 i64 16, ;; Align in Bits
1403 i64 0, ;; Offset in Bits
1404 i32 0, ;; Flags
1405 i32 5 ;; Encoding
1406}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1407</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1408</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1409
1410</div>
1411
1412<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1413<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1414 <a name="ccxx_basic_unsigned_short">unsigned short</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1415</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1416
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1417<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1418
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1419<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1420<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1421!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1422 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1423 metadata !1, ;; Context
1424 metadata !"short unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1425 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1426 i32 0, ;; Line number
1427 i64 16, ;; Size in Bits
1428 i64 16, ;; Align in Bits
1429 i64 0, ;; Offset in Bits
1430 i32 0, ;; Flags
1431 i32 7 ;; Encoding
1432}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1433</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1434</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1435
1436</div>
1437
1438<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1439<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1440 <a name="ccxx_basic_int">int</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1441</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1442
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1443<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1444
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1445<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1446<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1447!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1448 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1449 metadata !1, ;; Context
1450 metadata !"int", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1451 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1452 i32 0, ;; Line number
1453 i64 32, ;; Size in Bits
1454 i64 32, ;; Align in Bits
1455 i64 0, ;; Offset in Bits
1456 i32 0, ;; Flags
1457 i32 5 ;; Encoding
1458}
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1459</pre></div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1460
1461</div>
1462
1463<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1464<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1465 <a name="ccxx_basic_unsigned_int">unsigned int</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1466</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1467
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1468<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1469
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1470<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1471<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1472!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1473 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1474 metadata !1, ;; Context
1475 metadata !"unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1476 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1477 i32 0, ;; Line number
1478 i64 32, ;; Size in Bits
1479 i64 32, ;; Align in Bits
1480 i64 0, ;; Offset in Bits
1481 i32 0, ;; Flags
1482 i32 7 ;; Encoding
1483}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1484</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1485</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1486
1487</div>
1488
1489<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1490<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1491 <a name="ccxx_basic_long_long">long long</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1492</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1493
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1494<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1495
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1496<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1497<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1498!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1499 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1500 metadata !1, ;; Context
1501 metadata !"long long int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1502 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1503 i32 0, ;; Line number
1504 i64 64, ;; Size in Bits
1505 i64 64, ;; Align in Bits
1506 i64 0, ;; Offset in Bits
1507 i32 0, ;; Flags
1508 i32 5 ;; Encoding
1509}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1510</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1511</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1512
1513</div>
1514
1515<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1516<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1517 <a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1518</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1519
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1520<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1521
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1522<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1523<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1524!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1525 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1526 metadata !1, ;; Context
1527 metadata !"long long unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1528 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1529 i32 0, ;; Line number
1530 i64 64, ;; Size in Bits
1531 i64 64, ;; Align in Bits
1532 i64 0, ;; Offset in Bits
1533 i32 0, ;; Flags
1534 i32 7 ;; Encoding
1535}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1536</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1537</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1538
1539</div>
1540
1541<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1542<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1543 <a name="ccxx_basic_float">float</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1544</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1545
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1546<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1547
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1548<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1549<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1550!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1551 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1552 metadata !1, ;; Context
1553 metadata !"float",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1554 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1555 i32 0, ;; Line number
1556 i64 32, ;; Size in Bits
1557 i64 32, ;; Align in Bits
1558 i64 0, ;; Offset in Bits
1559 i32 0, ;; Flags
1560 i32 4 ;; Encoding
1561}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1562</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1563</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1564
1565</div>
1566
1567<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1568<h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1569 <a name="ccxx_basic_double">double</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1570</h4>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1571
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1572<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1573
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1574<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1575<pre>
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1576!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1577 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1578 metadata !1, ;; Context
1579 metadata !"double",;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1580 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1581 i32 0, ;; Line number
1582 i64 64, ;; Size in Bits
1583 i64 64, ;; Align in Bits
1584 i64 0, ;; Offset in Bits
1585 i32 0, ;; Flags
1586 i32 4 ;; Encoding
1587}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1588</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1589</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1590
1591</div>
1592
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1593</div>
1594
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1595<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1596<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1597 <a name="ccxx_derived_types">C/C++ derived types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1598</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1599
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1600<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1601
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1602<p>Given the following as an example of C/C++ derived type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1603
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1604<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1605<pre>
1606typedef const int *IntPtr;
1607</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1608</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1609
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1610<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1611
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1612<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1613<pre>
1614;;
1615;; Define the typedef "IntPtr".
1616;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1617!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1618 i32 524310, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1619 metadata !1, ;; Context
1620 metadata !"IntPtr", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1621 metadata !3, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1622 i32 0, ;; Line number
1623 i64 0, ;; Size in bits
1624 i64 0, ;; Align in bits
1625 i64 0, ;; Offset in bits
1626 i32 0, ;; Flags
1627 metadata !4 ;; Derived From type
1628}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1629
1630;;
1631;; Define the pointer type.
1632;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1633!4 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1634 i32 524303, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1635 metadata !1, ;; Context
1636 metadata !"", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1637 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1638 i32 0, ;; Line number
1639 i64 64, ;; Size in bits
1640 i64 64, ;; Align in bits
1641 i64 0, ;; Offset in bits
1642 i32 0, ;; Flags
1643 metadata !5 ;; Derived From type
1644}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1645;;
1646;; Define the const type.
1647;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1648!5 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1649 i32 524326, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1650 metadata !1, ;; Context
1651 metadata !"", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1652 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1653 i32 0, ;; Line number
1654 i64 32, ;; Size in bits
1655 i64 32, ;; Align in bits
1656 i64 0, ;; Offset in bits
1657 i32 0, ;; Flags
1658 metadata !6 ;; Derived From type
1659}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1660;;
1661;; Define the int type.
1662;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1663!6 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1664 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1665 metadata !1, ;; Context
1666 metadata !"int", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1667 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1668 i32 0, ;; Line number
1669 i64 32, ;; Size in bits
1670 i64 32, ;; Align in bits
1671 i64 0, ;; Offset in bits
1672 i32 0, ;; Flags
1673 5 ;; Encoding
1674}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1675</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1676</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1677
1678</div>
1679
1680<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1681<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1682 <a name="ccxx_composite_types">C/C++ struct/union types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1683</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1684
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1685<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1686
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1687<p>Given the following as an example of C/C++ struct type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1688
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1689<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1690<pre>
1691struct Color {
1692 unsigned Red;
1693 unsigned Green;
1694 unsigned Blue;
1695};
1696</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1697</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1698
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1699<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1700
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1701<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1702<pre>
1703;;
1704;; Define basic type for unsigned int.
1705;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1706!5 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1707 i32 524324, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1708 metadata !1, ;; Context
1709 metadata !"unsigned int",
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1710 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1711 i32 0, ;; Line number
1712 i64 32, ;; Size in Bits
1713 i64 32, ;; Align in Bits
1714 i64 0, ;; Offset in Bits
1715 i32 0, ;; Flags
1716 i32 7 ;; Encoding
1717}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1718;;
1719;; Define composite type for struct Color.
1720;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1721!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1722 i32 524307, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1723 metadata !1, ;; Context
1724 metadata !"Color", ;; Name
1725 metadata !1, ;; Compile unit
1726 i32 1, ;; Line number
1727 i64 96, ;; Size in bits
1728 i64 32, ;; Align in bits
1729 i64 0, ;; Offset in bits
1730 i32 0, ;; Flags
1731 null, ;; Derived From
1732 metadata !3, ;; Elements
1733 i32 0 ;; Runtime Language
1734}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1735
1736;;
1737;; Define the Red field.
1738;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1739!4 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1740 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1741 metadata !1, ;; Context
1742 metadata !"Red", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1743 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1744 i32 2, ;; Line number
1745 i64 32, ;; Size in bits
1746 i64 32, ;; Align in bits
1747 i64 0, ;; Offset in bits
1748 i32 0, ;; Flags
1749 metadata !5 ;; Derived From type
1750}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1751
1752;;
1753;; Define the Green field.
1754;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1755!6 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1756 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1757 metadata !1, ;; Context
1758 metadata !"Green", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1759 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1760 i32 3, ;; Line number
1761 i64 32, ;; Size in bits
1762 i64 32, ;; Align in bits
1763 i64 32, ;; Offset in bits
1764 i32 0, ;; Flags
1765 metadata !5 ;; Derived From type
1766}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1767
1768;;
1769;; Define the Blue field.
1770;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1771!7 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1772 i32 524301, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1773 metadata !1, ;; Context
1774 metadata !"Blue", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1775 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1776 i32 4, ;; Line number
1777 i64 32, ;; Size in bits
1778 i64 32, ;; Align in bits
1779 i64 64, ;; Offset in bits
1780 i32 0, ;; Flags
1781 metadata !5 ;; Derived From type
1782}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1783
1784;;
1785;; Define the array of fields used by the composite type Color.
1786;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1787!3 = metadata !{metadata !4, metadata !6, metadata !7}
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1788</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1789</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1790
1791</div>
1792
1793<!-- ======================================================================= -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1794<h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1795 <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000[diff] [blame]1796</h3>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1797
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1798<div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1799
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1800<p>Given the following as an example of C/C++ enumeration type:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1801
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1802<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1803<pre>
1804enum Trees {
1805 Spruce = 100,
1806 Oak = 200,
1807 Maple = 300
1808};
1809</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1810</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1811
Misha Brukman96e00812008-12-16 02:54:22 +0000[diff] [blame]1812<p>a C/C++ front-end would generate the following descriptors:</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1813
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1814<div class="doc_code">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1815<pre>
1816;;
1817;; Define composite type for enum Trees
1818;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1819!2 = metadata !{
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1820 i32 524292, ;; Tag
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1821 metadata !1, ;; Context
1822 metadata !"Trees", ;; Name
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1823 metadata !1, ;; File
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1824 i32 1, ;; Line number
1825 i64 32, ;; Size in bits
1826 i64 32, ;; Align in bits
1827 i64 0, ;; Offset in bits
1828 i32 0, ;; Flags
1829 null, ;; Derived From type
1830 metadata !3, ;; Elements
1831 i32 0 ;; Runtime language
1832}
Devang Patel2a610c72009-08-25 05:24:07 +0000[diff] [blame]1833
Devang Patel82459882009-08-26 05:01:18 +0000[diff] [blame]1834;;
1835;; Define the array of enumerators used by composite type Trees.
1836;;
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1837!3 = metadata !{metadata !4, metadata !5, metadata !6}
1838
1839;;
1840;; Define Spruce enumerator.
1841;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1842!4 = metadata !{i32 524328, metadata !"Spruce", i64 100}
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1843
1844;;
1845;; Define Oak enumerator.
1846;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1847!5 = metadata !{i32 524328, metadata !"Oak", i64 200}
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1848
1849;;
1850;; Define Maple enumerator.
1851;;
Devang Patel4b945502010-03-09 00:44:10 +0000[diff] [blame]1852!6 = metadata !{i32 524328, metadata !"Maple", i64 300}
Devang Patele4b27562009-08-28 23:24:31 +0000[diff] [blame]1853
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1854</pre>
Bill Wendling48839d92009-05-17 05:52:39 +0000[diff] [blame]1855</div>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1856
1857</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1858
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000[diff] [blame]1859</div>
1860
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1861
1862<!-- *********************************************************************** -->
1863<h2>
1864 <a name="llvmdwarfextension">Debugging information format</a>
1865</h2>
1866<!-- *********************************************************************** -->
1867<div>
1868<!-- ======================================================================= -->
1869<h3>
Bill Wendling0eb59142012-03-06 09:17:39 +0000[diff] [blame]1870 <a name="objcproperty">Debugging Information Extension for Objective C Properties</a>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1871</h3>
1872<div>
1873<!-- *********************************************************************** -->
1874<h4>
1875 <a name="objcpropertyintroduction">Introduction</a>
1876</h4>
1877<!-- *********************************************************************** -->
1878
1879<div>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1880<p>Objective C provides a simpler way to declare and define accessor methods
1881using declared properties. The language provides features to declare a
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1882property and to let compiler synthesize accessor methods.
1883</p>
1884
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1885<p>The debugger lets developer inspect Objective C interfaces and their
1886instance variables and class variables. However, the debugger does not know
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1887anything about the properties defined in Objective C interfaces. The debugger
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1888consumes information generated by compiler in DWARF format. The format does
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1889not support encoding of Objective C properties. This proposal describes DWARF
1890extensions to encode Objective C properties, which the debugger can use to let
1891developers inspect Objective C properties.
1892</p>
1893
1894</div>
1895
1896
1897<!-- *********************************************************************** -->
1898<h4>
1899 <a name="objcpropertyproposal">Proposal</a>
1900</h4>
1901<!-- *********************************************************************** -->
1902
1903<div>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1904<p>Objective C properties exist separately from class members. A property
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1905can be defined only by &quot;setter&quot; and &quot;getter&quot; selectors, and
1906be calculated anew on each access. Or a property can just be a direct access
1907to some declared ivar. Finally it can have an ivar &quot;automatically
1908synthesized&quot; for it by the compiler, in which case the property can be
1909referred to in user code directly using the standard C dereference syntax as
1910well as through the property &quot;dot&quot; syntax, but there is no entry in
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1911the @interface declaration corresponding to this ivar.
1912</p>
1913<p>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1914To facilitate debugging, these properties we will add a new DWARF TAG into the
1915DW_TAG_structure_type definition for the class to hold the description of a
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1916given property, and a set of DWARF attributes that provide said description.
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1917The property tag will also contain the name and declared type of the property.
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1918</p>
1919<p>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1920If there is a related ivar, there will also be a DWARF property attribute placed
1921in the DW_TAG_member DIE for that ivar referring back to the property TAG for
1922that property. And in the case where the compiler synthesizes the ivar directly,
1923the compiler is expected to generate a DW_TAG_member for that ivar (with the
1924DW_AT_artificial set to 1), whose name will be the name used to access this
1925ivar directly in code, and with the property attribute pointing back to the
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1926property it is backing.
1927</p>
1928<p>
1929The following examples will serve as illustration for our discussion:
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1930</p>
1931
1932<div class="doc_code">
1933<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1934@interface I1 {
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1935 int n2;
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1936}
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1937
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1938@property int p1;
1939@property int p2;
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1940@end
1941
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1942@implementation I1
1943@synthesize p1;
1944@synthesize p2 = n2;
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1945@end
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1946</pre>
1947</div>
1948
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1949<p>
1950This produces the following DWARF (this is a &quot;pseudo dwarfdump&quot; output):
1951</p>
1952<div class="doc_code">
1953<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]19540x00000100: TAG_structure_type [7] *
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1955 AT_APPLE_runtime_class( 0x10 )
1956 AT_name( "I1" )
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1957 AT_decl_file( "Objc_Property.m" )
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1958 AT_decl_line( 3 )
1959
19600x00000110 TAG_APPLE_property
1961 AT_name ( "p1" )
1962 AT_type ( {0x00000150} ( int ) )
1963
19640x00000120: TAG_APPLE_property
1965 AT_name ( "p2" )
1966 AT_type ( {0x00000150} ( int ) )
1967
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]19680x00000130: TAG_member [8]
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1969 AT_name( "_p1" )
1970 AT_APPLE_property ( {0x00000110} "p1" )
1971 AT_type( {0x00000150} ( int ) )
1972 AT_artificial ( 0x1 )
1973
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]19740x00000140: TAG_member [8]
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1975 AT_name( "n2" )
1976 AT_APPLE_property ( {0x00000120} "p2" )
1977 AT_type( {0x00000150} ( int ) )
1978
19790x00000150: AT_type( ( int ) )
1980</pre>
1981</div>
1982
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1983<p> Note, the current convention is that the name of the ivar for an
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1984auto-synthesized property is the name of the property from which it derives with
1985an underscore prepended, as is shown in the example.
1986But we actually don't need to know this convention, since we are given the name
1987of the ivar directly.
1988</p>
1989
1990<p>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1991Also, it is common practice in ObjC to have different property declarations in
1992the @interface and @implementation - e.g. to provide a read-only property in
1993the interface,and a read-write interface in the implementation. In that case,
1994the compiler should emit whichever property declaration will be in force in the
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]1995current translation unit.
1996</p>
1997
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]1998<p> Developers can decorate a property with attributes which are encoded using
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]1999DW_AT_APPLE_property_attribute.
2000</p>
2001
2002<div class="doc_code">
2003<pre>
2004@property (readonly, nonatomic) int pr;
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2005</pre>
2006</div>
2007<p>
2008Which produces a property tag:
2009<p>
2010<div class="doc_code">
2011<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2012TAG_APPLE_property [8]
2013 AT_name( "pr" )
2014 AT_type ( {0x00000147} (int) )
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2015 AT_APPLE_property_attribute (DW_APPLE_PROPERTY_readonly, DW_APPLE_PROPERTY_nonatomic)
2016</pre>
2017</div>
2018
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2019<p> The setter and getter method names are attached to the property using
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2020DW_AT_APPLE_property_setter and DW_AT_APPLE_property_getter attributes.
2021</p>
2022<div class="doc_code">
2023<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2024@interface I1
2025@property (setter=myOwnP3Setter:) int p3;
2026-(void)myOwnP3Setter:(int)a;
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2027@end
2028
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2029@implementation I1
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2030@synthesize p3;
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2031-(void)myOwnP3Setter:(int)a{ }
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2032@end
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2033</pre>
2034</div>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2035
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2036<p>
2037The DWARF for this would be:
2038</p>
2039<div class="doc_code">
2040<pre>
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]20410x000003bd: TAG_structure_type [7] *
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2042 AT_APPLE_runtime_class( 0x10 )
2043 AT_name( "I1" )
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2044 AT_decl_file( "Objc_Property.m" )
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2045 AT_decl_line( 3 )
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2046
20470x000003cd TAG_APPLE_property
2048 AT_name ( "p3" )
2049 AT_APPLE_property_setter ( "myOwnP3Setter:" )
2050 AT_type( {0x00000147} ( int ) )
Eric Christopherfc7243a2012-03-06 02:25:36 +0000[diff] [blame]2051
20520x000003f3: TAG_member [8]
2053 AT_name( "_p3" )
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2054 AT_type ( {0x00000147} ( int ) )
2055 AT_APPLE_property ( {0x000003cd} )
2056 AT_artificial ( 0x1 )
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2057</pre>
2058</div>
2059
2060</div>
2061
2062<!-- *********************************************************************** -->
2063<h4>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2064 <a name="objcpropertynewtags">New DWARF Tags</a>
2065</h4>
2066<!-- *********************************************************************** -->
2067
2068<div>
2069<table border="1" cellspacing="0">
Bill Wendlingcf1f6c82012-03-06 09:22:03 +0000[diff] [blame]2070 <col width="200">
2071 <col width="200">
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2072 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2073 <th>TAG</th>
2074 <th>Value</th>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2075 </tr>
2076 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2077 <td>DW_TAG_APPLE_property</td>
2078 <td>0x4200</td>
Devang Patelba98b6b2012-02-06 18:18:25 +0000[diff] [blame]2079 </tr>
2080</table>
2081
2082</div>
2083
2084<!-- *********************************************************************** -->
2085<h4>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2086 <a name="objcpropertynewattributes">New DWARF Attributes</a>
2087</h4>
2088<!-- *********************************************************************** -->
2089
2090<div>
2091<table border="1" cellspacing="0">
Bill Wendlingcf1f6c82012-03-06 09:22:03 +0000[diff] [blame]2092 <col width="200">
2093 <col width="200">
2094 <col width="200">
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2095 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2096 <th>Attribute</th>
2097 <th>Value</th>
2098 <th>Classes</th>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2099 </tr>
2100 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2101 <td>DW_AT_APPLE_property</td>
2102 <td>0x3fed</td>
2103 <td>Reference</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2104 </tr>
2105 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2106 <td>DW_AT_APPLE_property_getter</td>
2107 <td>0x3fe9</td>
2108 <td>String</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2109 </tr>
2110 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2111 <td>DW_AT_APPLE_property_setter</td>
2112 <td>0x3fea</td>
2113 <td>String</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2114 </tr>
2115 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2116 <td>DW_AT_APPLE_property_attribute</td>
2117 <td>0x3feb</td>
2118 <td>Constant</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2119 </tr>
2120</table>
2121
2122</div>
2123
2124<!-- *********************************************************************** -->
2125<h4>
2126 <a name="objcpropertynewconstants">New DWARF Constants</a>
2127</h4>
2128<!-- *********************************************************************** -->
2129
2130<div>
2131<table border="1" cellspacing="0">
Bill Wendlingcf1f6c82012-03-06 09:22:03 +0000[diff] [blame]2132 <col width="200">
2133 <col width="200">
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2134 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2135 <th>Name</th>
2136 <th>Value</th>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2137 </tr>
2138 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2139 <td>DW_AT_APPLE_PROPERTY_readonly</td>
2140 <td>0x1</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2141 </tr>
2142 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2143 <td>DW_AT_APPLE_PROPERTY_readwrite</td>
2144 <td>0x2</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2145 </tr>
2146 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2147 <td>DW_AT_APPLE_PROPERTY_assign</td>
2148 <td>0x4</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2149 </tr>
2150 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2151 <td>DW_AT_APPLE_PROPERTY_retain</td>
2152 <td>0x8</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2153 </tr>
2154 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2155 <td>DW_AT_APPLE_PROPERTY_copy</td>
2156 <td>0x10</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2157 </tr>
2158 <tr>
Bill Wendling63f5a1f2012-03-06 09:20:59 +0000[diff] [blame]2159 <td>DW_AT_APPLE_PROPERTY_nonatomic</td>
2160 <td>0x20</td>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2161 </tr>
2162</table>
2163
2164</div>
2165</div>
Devang Patel6ac5b162011-11-15 22:59:54 +0000[diff] [blame]2166
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2167<!-- ======================================================================= -->
2168<h3>
2169 <a name="acceltable">Name Accelerator Tables</a>
2170</h3>
2171<!-- ======================================================================= -->
NAKAMURA Takumi9c55f592012-03-27 11:25:16 +0000[diff] [blame]2172<div>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2173<!-- ======================================================================= -->
2174<h4>
Eric Christopher5b7634f2012-03-06 02:25:41 +0000[diff] [blame]2175 <a name="acceltableintroduction">Introduction</a>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2176</h4>
2177<!-- ======================================================================= -->
2178<div>
2179<p>The .debug_pubnames and .debug_pubtypes formats are not what a debugger
2180 needs. The "pub" in the section name indicates that the entries in the
2181 table are publicly visible names only. This means no static or hidden
2182 functions show up in the .debug_pubnames. No static variables or private class
2183 variables are in the .debug_pubtypes. Many compilers add different things to
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2184 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]2185
2186<p>The typical query given by users tends not to match up with the contents of
2187 these tables. For example, the DWARF spec states that "In the case of the
2188 name of a function member or static data member of a C++ structure, class or
2189 union, the name presented in the .debug_pubnames section is not the simple
2190 name given by the DW_AT_name attribute of the referenced debugging information
2191 entry, but rather the fully qualified name of the data or function member."
2192 So the only names in these tables for complex C++ entries is a fully
2193 qualified name. Debugger users tend not to enter their search strings as
2194 "a::b::c(int,const Foo&) const", but rather as "c", "b::c" , or "a::b::c". So
2195 the name entered in the name table must be demangled in order to chop it up
2196 appropriately and additional names must be manually entered into the table
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2197 to make it effective as a name lookup table for debuggers to use.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2198
2199<p>All debuggers currently ignore the .debug_pubnames table as a result of
2200 its inconsistent and useless public-only name content making it a waste of
2201 space in the object file. These tables, when they are written to disk, are
2202 not sorted in any way, leaving every debugger to do its own parsing
2203 and sorting. These tables also include an inlined copy of the string values
2204 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]2205 disk, especially for large C++ programs.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2206
2207<p>Can't we just fix the sections by adding all of the names we need to this
2208 table? No, because that is not what the tables are defined to contain and we
2209 won't know the difference between the old bad tables and the new good tables.
2210 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]2211 we need.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2212
2213<p>These tables are also insufficient for what a debugger like LLDB needs.
2214 LLDB uses clang for its expression parsing where LLDB acts as a PCH. LLDB is
2215 then often asked to look for type "foo" or namespace "bar", or list items in
2216 namespace "baz". Namespaces are not included in the pubnames or pubtypes
2217 tables. Since clang asks a lot of questions when it is parsing an expression,
2218 we need to be very fast when looking up names, as it happens a lot. Having new
2219 accelerator tables that are optimized for very quick lookups will benefit
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2220 this type of debugging experience greatly.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2221
2222<p>We would like to generate name lookup tables that can be mapped into
2223 memory from disk, and used as is, with little or no up-front parsing. We would
2224 also be able to control the exact content of these different tables so they
2225 contain exactly what we need. The Name Accelerator Tables were designed
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2226 to fix these issues. In order to solve these issues we need to:</p>
2227
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2228<ul>
2229 <li>Have a format that can be mapped into memory from disk and used as is</li>
2230 <li>Lookups should be very fast</li>
2231 <li>Extensible table format so these tables can be made by many producers</li>
2232 <li>Contain all of the names needed for typical lookups out of the box</li>
2233 <li>Strict rules for the contents of tables</li>
2234</ul>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2235
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2236<p>Table size is important and the accelerator table format should allow the
2237 reuse of strings from common string tables so the strings for the names are
2238 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]2239 by simply mapping the table into memory with minimal header parsing.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2240
2241<p>The name lookups need to be fast and optimized for the kinds of lookups
2242 that debuggers tend to do. Optimally we would like to touch as few parts of
2243 the mapped table as possible when doing a name lookup and be able to quickly
2244 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]2245 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]2246
2247<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]2248 the accelerator tables and documented so clients can rely on the content.</p>
2249
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2250</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2251
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2252<!-- ======================================================================= -->
2253<h4>
2254 <a name="acceltablehashes">Hash Tables</a>
2255</h4>
2256<!-- ======================================================================= -->
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2257
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2258<div>
2259<h5>Standard Hash Tables</h5>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2260
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2261<p>Typical hash tables have a header, buckets, and each bucket points to the
2262bucket contents:
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2263</p>
2264
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2265<div class="doc_code">
2266<pre>
2267.------------.
2268| HEADER |
2269|------------|
2270| BUCKETS |
2271|------------|
2272| DATA |
2273`------------'
2274</pre>
2275</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2276
2277<p>The BUCKETS are an array of offsets to DATA for each hash:</p>
2278
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2279<div class="doc_code">
2280<pre>
2281.------------.
2282| 0x00001000 | BUCKETS[0]
2283| 0x00002000 | BUCKETS[1]
2284| 0x00002200 | BUCKETS[2]
2285| 0x000034f0 | BUCKETS[3]
2286| | ...
2287| 0xXXXXXXXX | BUCKETS[n_buckets]
2288'------------'
2289</pre>
2290</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2291
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2292<p>So for bucket[3] in the example above, we have an offset into the table
2293 0x000034f0 which points to a chain of entries for the bucket. Each bucket
2294 must contain a next pointer, full 32 bit hash value, the string itself,
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2295 and the data for the current string value.</p>
2296
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2297<div class="doc_code">
2298<pre>
2299 .------------.
23000x000034f0: | 0x00003500 | next pointer
2301 | 0x12345678 | 32 bit hash
2302 | "erase" | string value
2303 | data[n] | HashData for this bucket
2304 |------------|
23050x00003500: | 0x00003550 | next pointer
2306 | 0x29273623 | 32 bit hash
2307 | "dump" | string value
2308 | data[n] | HashData for this bucket
2309 |------------|
23100x00003550: | 0x00000000 | next pointer
2311 | 0x82638293 | 32 bit hash
2312 | "main" | string value
2313 | data[n] | HashData for this bucket
2314 `------------'
2315</pre>
2316</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2317
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2318<p>The problem with this layout for debuggers is that we need to optimize for
2319 the negative lookup case where the symbol we're searching for is not present.
2320 So if we were to lookup "printf" in the table above, we would make a 32 hash
2321 for "printf", it might match bucket[3]. We would need to go to the offset
2322 0x000034f0 and start looking to see if our 32 bit hash matches. To do so, we
2323 need to read the next pointer, then read the hash, compare it, and skip to
2324 the next bucket. Each time we are skipping many bytes in memory and touching
2325 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]2326 accesses then tell us that we didn't have a match.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2327
2328<h5>Name Hash Tables</h5>
2329
2330<p>To solve the issues mentioned above we have structured the hash tables
2331 a bit differently: a header, buckets, an array of all unique 32 bit hash
2332 values, followed by an array of hash value data offsets, one for each hash
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2333 value, then the data for all hash values:</p>
2334
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2335<div class="doc_code">
2336<pre>
2337.-------------.
2338| HEADER |
2339|-------------|
2340| BUCKETS |
2341|-------------|
2342| HASHES |
2343|-------------|
2344| OFFSETS |
2345|-------------|
2346| DATA |
2347`-------------'
2348</pre>
2349</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2350
Eric Christopher5b7634f2012-03-06 02:25:41 +0000[diff] [blame]2351<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]2352 making all of the full 32 bit hash values contiguous in memory, we allow
2353 ourselves to efficiently check for a match while touching as little
Eric Christopher5b7634f2012-03-06 02:25:41 +0000[diff] [blame]2354 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]2355 the lookup goes. If it does match, it usually is a match with no collisions.
2356 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]2357 values, we can clarify the contents of the BUCKETS, HASHES and OFFSETS as:</p>
2358
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2359<div class="doc_code">
2360<pre>
2361.-------------------------.
2362| HEADER.magic | uint32_t
2363| HEADER.version | uint16_t
2364| HEADER.hash_function | uint16_t
2365| HEADER.bucket_count | uint32_t
2366| HEADER.hashes_count | uint32_t
2367| HEADER.header_data_len | uint32_t
2368| HEADER_DATA | HeaderData
2369|-------------------------|
2370| BUCKETS | uint32_t[n_buckets] // 32 bit hash indexes
2371|-------------------------|
2372| HASHES | uint32_t[n_buckets] // 32 bit hash values
2373|-------------------------|
2374| OFFSETS | uint32_t[n_buckets] // 32 bit offsets to hash value data
2375|-------------------------|
2376| ALL HASH DATA |
2377`-------------------------'
2378</pre>
2379</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2380
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2381<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]2382 with:</p>
2383
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2384<div class="doc_code">
2385<pre>
2386 .------------.
2387 | HEADER |
2388 |------------|
2389 | 0 | BUCKETS[0]
2390 | 2 | BUCKETS[1]
2391 | 5 | BUCKETS[2]
2392 | 6 | BUCKETS[3]
2393 | | ...
2394 | ... | BUCKETS[n_buckets]
2395 |------------|
2396 | 0x........ | HASHES[0]
2397 | 0x........ | HASHES[1]
2398 | 0x........ | HASHES[2]
2399 | 0x........ | HASHES[3]
2400 | 0x........ | HASHES[4]
2401 | 0x........ | HASHES[5]
2402 | 0x12345678 | HASHES[6] hash for BUCKETS[3]
2403 | 0x29273623 | HASHES[7] hash for BUCKETS[3]
2404 | 0x82638293 | HASHES[8] hash for BUCKETS[3]
2405 | 0x........ | HASHES[9]
2406 | 0x........ | HASHES[10]
2407 | 0x........ | HASHES[11]
2408 | 0x........ | HASHES[12]
2409 | 0x........ | HASHES[13]
2410 | 0x........ | HASHES[n_hashes]
2411 |------------|
2412 | 0x........ | OFFSETS[0]
2413 | 0x........ | OFFSETS[1]
2414 | 0x........ | OFFSETS[2]
2415 | 0x........ | OFFSETS[3]
2416 | 0x........ | OFFSETS[4]
2417 | 0x........ | OFFSETS[5]
2418 | 0x000034f0 | OFFSETS[6] offset for BUCKETS[3]
2419 | 0x00003500 | OFFSETS[7] offset for BUCKETS[3]
2420 | 0x00003550 | OFFSETS[8] offset for BUCKETS[3]
2421 | 0x........ | OFFSETS[9]
2422 | 0x........ | OFFSETS[10]
2423 | 0x........ | OFFSETS[11]
2424 | 0x........ | OFFSETS[12]
2425 | 0x........ | OFFSETS[13]
2426 | 0x........ | OFFSETS[n_hashes]
2427 |------------|
2428 | |
2429 | |
2430 | |
2431 | |
2432 | |
2433 |------------|
24340x000034f0: | 0x00001203 | .debug_str ("erase")
2435 | 0x00000004 | A 32 bit array count - number of HashData with name "erase"
2436 | 0x........ | HashData[0]
2437 | 0x........ | HashData[1]
2438 | 0x........ | HashData[2]
2439 | 0x........ | HashData[3]
2440 | 0x00000000 | String offset into .debug_str (terminate data for hash)
2441 |------------|
24420x00003500: | 0x00001203 | String offset into .debug_str ("collision")
2443 | 0x00000002 | A 32 bit array count - number of HashData with name "collision"
2444 | 0x........ | HashData[0]
2445 | 0x........ | HashData[1]
2446 | 0x00001203 | String offset into .debug_str ("dump")
2447 | 0x00000003 | A 32 bit array count - number of HashData with name "dump"
2448 | 0x........ | HashData[0]
2449 | 0x........ | HashData[1]
2450 | 0x........ | HashData[2]
2451 | 0x00000000 | String offset into .debug_str (terminate data for hash)
2452 |------------|
24530x00003550: | 0x00001203 | String offset into .debug_str ("main")
2454 | 0x00000009 | A 32 bit array count - number of HashData with name "main"
2455 | 0x........ | HashData[0]
2456 | 0x........ | HashData[1]
2457 | 0x........ | HashData[2]
2458 | 0x........ | HashData[3]
2459 | 0x........ | HashData[4]
2460 | 0x........ | HashData[5]
2461 | 0x........ | HashData[6]
2462 | 0x........ | HashData[7]
2463 | 0x........ | HashData[8]
2464 | 0x00000000 | String offset into .debug_str (terminate data for hash)
2465 `------------'
2466</pre>
2467</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2468
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2469<p>So we still have all of the same data, we just organize it more efficiently
2470 for debugger lookup. If we repeat the same "printf" lookup from above, we
2471 would hash "printf" and find it matches BUCKETS[3] by taking the 32 bit hash
2472 value and modulo it by n_buckets. BUCKETS[3] contains "6" which is the index
2473 into the HASHES table. We would then compare any consecutive 32 bit hashes
2474 values in the HASHES array as long as the hashes would be in BUCKETS[3]. We
2475 do this by verifying that each subsequent hash value modulo n_buckets is still
2476 3. In the case of a failed lookup we would access the memory for BUCKETS[3], and
2477 then compare a few consecutive 32 bit hashes before we know that we have no match.
2478 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]2479 number of processor data cache lines being accessed as small as possible.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2480
2481<p>The string hash that is used for these lookup tables is the Daniel J.
2482 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]2483 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]2484
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2485<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]2486</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2487
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2488<!-- ======================================================================= -->
2489<h4>
2490 <a name="acceltabledetails">Details</a>
2491</h4>
2492<!-- ======================================================================= -->
2493<div>
2494<p>These name hash tables are designed to be generic where specializations of
2495 the table get to define additional data that goes into the header
2496 ("HeaderData"), how the string value is stored ("KeyType") and the content
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2497 of the data for each hash value.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2498
2499<h5>Header Layout</h5>
2500<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]2501 the header is:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2502<div class="doc_code">
2503<pre>
2504struct Header
2505{
2506 uint32_t magic; // 'HASH' magic value to allow endian detection
2507 uint16_t version; // Version number
2508 uint16_t hash_function; // The hash function enumeration that was used
2509 uint32_t bucket_count; // The number of buckets in this hash table
2510 uint32_t hashes_count; // The total number of unique hash values and hash data offsets in this table
2511 uint32_t header_data_len; // The bytes to skip to get to the hash indexes (buckets) for correct alignment
2512 // Specifically the length of the following HeaderData field - this does not
2513 // include the size of the preceding fields
2514 HeaderData header_data; // Implementation specific header data
2515};
2516</pre>
2517</div>
2518<p>The header starts with a 32 bit "magic" value which must be 'HASH' encoded as
2519 an ASCII integer. This allows the detection of the start of the hash table and
2520 also allows the table's byte order to be determined so the table can be
2521 correctly extracted. The "magic" value is followed by a 16 bit version number
2522 which allows the table to be revised and modified in the future. The current
2523 version number is 1. "hash_function" is a uint16_t enumeration that specifies
2524 which hash function was used to produce this table. The current values for the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2525 hash function enumerations include:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2526<div class="doc_code">
2527<pre>
2528enum HashFunctionType
2529{
2530 eHashFunctionDJB = 0u, // Daniel J Bernstein hash function
2531};
2532</pre>
2533</div>
2534<p>"bucket_count" is a 32 bit unsigned integer that represents how many buckets
2535 are in the BUCKETS array. "hashes_count" is the number of unique 32 bit hash
2536 values that are in the HASHES array, and is the same number of offsets are
2537 contained in the OFFSETS array. "header_data_len" specifies the size in
2538 bytes of the HeaderData that is filled in by specialized versions of this
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2539 table.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2540
2541<h5>Fixed Lookup</h5>
2542<p>The header is followed by the buckets, hashes, offsets, and hash value
2543 data.
2544<div class="doc_code">
2545<pre>
2546struct FixedTable
2547{
2548 uint32_t buckets[Header.bucket_count]; // An array of hash indexes into the "hashes[]" array below
2549 uint32_t hashes [Header.hashes_count]; // Every unique 32 bit hash for the entire table is in this table
2550 uint32_t offsets[Header.hashes_count]; // An offset that corresponds to each item in the "hashes[]" array above
2551};
2552</pre>
2553</div>
2554<p>"buckets" is an array of 32 bit indexes into the "hashes" array. The
2555 "hashes" array contains all of the 32 bit hash values for all names in the
2556 hash table. Each hash in the "hashes" table has an offset in the "offsets"
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2557 array that points to the data for the hash value.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2558
2559<p>This table setup makes it very easy to repurpose these tables to contain
2560 different data, while keeping the lookup mechanism the same for all tables.
2561 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]2562 later and do very efficient name lookups with little or no parsing.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2563
2564<p>DWARF lookup tables can be implemented in a variety of ways and can store
2565 a lot of information for each name. We want to make the DWARF tables
2566 extensible and able to store the data efficiently so we have used some of the
2567 DWARF features that enable efficient data storage to define exactly what kind
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2568 of data we store for each name.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2569
2570<p>The "HeaderData" contains a definition of the contents of each HashData
2571 chunk. We might want to store an offset to all of the debug information
2572 entries (DIEs) for each name. To keep things extensible, we create a list of
2573 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]2574 type of the data in each atom:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2575<div class="doc_code">
2576<pre>
2577enum AtomType
2578{
2579 eAtomTypeNULL = 0u,
2580 eAtomTypeDIEOffset = 1u, // DIE offset, check form for encoding
2581 eAtomTypeCUOffset = 2u, // DIE offset of the compiler unit header that contains the item in question
2582 eAtomTypeTag = 3u, // DW_TAG_xxx value, should be encoded as DW_FORM_data1 (if no tags exceed 255) or DW_FORM_data2
2583 eAtomTypeNameFlags = 4u, // Flags from enum NameFlags
2584 eAtomTypeTypeFlags = 5u, // Flags from enum TypeFlags
2585};
2586</pre>
2587</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2588<p>The enumeration values and their meanings are:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2589<div class="doc_code">
2590<pre>
2591 eAtomTypeNULL - a termination atom that specifies the end of the atom list
2592 eAtomTypeDIEOffset - an offset into the .debug_info section for the DWARF DIE for this name
2593 eAtomTypeCUOffset - an offset into the .debug_info section for the CU that contains the DIE
2594 eAtomTypeDIETag - The DW_TAG_XXX enumeration value so you don't have to parse the DWARF to see what it is
2595 eAtomTypeNameFlags - Flags for functions and global variables (isFunction, isInlined, isExternal...)
2596 eAtomTypeTypeFlags - Flags for types (isCXXClass, isObjCClass, ...)
2597</pre>
2598</div>
2599<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]2600 each atom type data is encoded:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2601<div class="doc_code">
2602<pre>
2603struct Atom
2604{
2605 uint16_t type; // AtomType enum value
2606 uint16_t form; // DWARF DW_FORM_XXX defines
2607};
2608</pre>
2609</div>
2610<p>The "form" type above is from the DWARF specification and defines the
2611 exact encoding of the data for the Atom type. See the DWARF specification for
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2612 the DW_FORM_ definitions.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2613<div class="doc_code">
2614<pre>
2615struct HeaderData
2616{
2617 uint32_t die_offset_base;
2618 uint32_t atom_count;
2619 Atoms atoms[atom_count0];
2620};
2621</pre>
2622</div>
2623<p>"HeaderData" defines the base DIE offset that should be added to any atoms
2624 that are encoded using the DW_FORM_ref1, DW_FORM_ref2, DW_FORM_ref4,
2625 DW_FORM_ref8 or DW_FORM_ref_udata. It also defines what is contained in
2626 each "HashData" object -- Atom.form tells us how large each field will be in
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2627 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]2628
2629<p>For the current implementations of the ".apple_names" (all functions + globals),
2630 the ".apple_types" (names of all types that are defined), and the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2631 ".apple_namespaces" (all namespaces), we currently set the Atom array to be:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2632<div class="doc_code">
2633<pre>
2634HeaderData.atom_count = 1;
2635HeaderData.atoms[0].type = eAtomTypeDIEOffset;
2636HeaderData.atoms[0].form = DW_FORM_data4;
2637</pre>
2638</div>
2639<p>This defines the contents to be the DIE offset (eAtomTypeDIEOffset) that is
2640 encoded as a 32 bit value (DW_FORM_data4). This allows a single name to have
2641 multiple matching DIEs in a single file, which could come up with an inlined
2642 function for instance. Future tables could include more information about the
2643 DIE such as flags indicating if the DIE is a function, method, block,
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2644 or inlined.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2645
2646<p>The KeyType for the DWARF table is a 32 bit string table offset into the
2647 ".debug_str" table. The ".debug_str" is the string table for the DWARF which
2648 may already contain copies of all of the strings. This helps make sure, with
2649 help from the compiler, that we reuse the strings between all of the DWARF
2650 sections and keeps the hash table size down. Another benefit to having the
2651 compiler generate all strings as DW_FORM_strp in the debug info, is that
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2652 DWARF parsing can be made much faster.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2653
2654<p>After a lookup is made, we get an offset into the hash data. The hash data
2655 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]2656 at the offset in the hash data consists of a triple:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2657<div class="doc_code">
2658<pre>
2659uint32_t str_offset
2660uint32_t hash_data_count
2661HashData[hash_data_count]
2662</pre>
2663</div>
2664<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]2665 hash data chunks contain a single item (no 32 bit hash collision):</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2666<div class="doc_code">
2667<pre>
2668.------------.
2669| 0x00001023 | uint32_t KeyType (.debug_str[0x0001023] => "main")
2670| 0x00000004 | uint32_t HashData count
2671| 0x........ | uint32_t HashData[0] DIE offset
2672| 0x........ | uint32_t HashData[1] DIE offset
2673| 0x........ | uint32_t HashData[2] DIE offset
2674| 0x........ | uint32_t HashData[3] DIE offset
2675| 0x00000000 | uint32_t KeyType (end of hash chain)
2676`------------'
2677</pre>
2678</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2679<p>If there are collisions, you will have multiple valid string offsets:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2680<div class="doc_code">
2681<pre>
2682.------------.
2683| 0x00001023 | uint32_t KeyType (.debug_str[0x0001023] => "main")
2684| 0x00000004 | uint32_t HashData count
2685| 0x........ | uint32_t HashData[0] DIE offset
2686| 0x........ | uint32_t HashData[1] DIE offset
2687| 0x........ | uint32_t HashData[2] DIE offset
2688| 0x........ | uint32_t HashData[3] DIE offset
2689| 0x00002023 | uint32_t KeyType (.debug_str[0x0002023] => "print")
2690| 0x00000002 | uint32_t HashData count
2691| 0x........ | uint32_t HashData[0] DIE offset
2692| 0x........ | uint32_t HashData[1] DIE offset
2693| 0x00000000 | uint32_t KeyType (end of hash chain)
2694`------------'
2695</pre>
2696</div>
2697<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]2698 32 bit hash collision per 100,000 name entries.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2699</div>
2700<!-- ======================================================================= -->
2701<h4>
2702 <a name="acceltablecontents">Contents</a>
2703</h4>
2704<!-- ======================================================================= -->
2705<div>
2706<p>As we said, we want to strictly define exactly what is included in the
2707 different tables. For DWARF, we have 3 tables: ".apple_names", ".apple_types",
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2708 and ".apple_namespaces".</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2709
2710<p>".apple_names" sections should contain an entry for each DWARF DIE whose
2711 DW_TAG is a DW_TAG_label, DW_TAG_inlined_subroutine, or DW_TAG_subprogram that
2712 has address attributes: DW_AT_low_pc, DW_AT_high_pc, DW_AT_ranges or
2713 DW_AT_entry_pc. It also contains DW_TAG_variable DIEs that have a DW_OP_addr
2714 in the location (global and static variables). All global and static variables
Benjamin Kramerd9b0b022012-06-02 10:20:22 +0000[diff] [blame^]2715 should be included, including those scoped within functions and classes. For
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2716 example using the following code:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2717<div class="doc_code">
2718<pre>
2719static int var = 0;
2720
2721void f ()
2722{
2723 static int var = 0;
2724}
2725</pre>
2726</div>
2727<p>Both of the static "var" variables would be included in the table. All
2728 functions should emit both their full names and their basenames. For C or C++,
2729 the full name is the mangled name (if available) which is usually in the
2730 DW_AT_MIPS_linkage_name attribute, and the DW_AT_name contains the function
2731 basename. If global or static variables have a mangled name in a
2732 DW_AT_MIPS_linkage_name attribute, this should be emitted along with the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2733 simple name found in the DW_AT_name attribute.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2734
2735<p>".apple_types" sections should contain an entry for each DWARF DIE whose
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2736 tag is one of:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2737<ul>
2738 <li>DW_TAG_array_type</li>
2739 <li>DW_TAG_class_type</li>
2740 <li>DW_TAG_enumeration_type</li>
2741 <li>DW_TAG_pointer_type</li>
2742 <li>DW_TAG_reference_type</li>
2743 <li>DW_TAG_string_type</li>
2744 <li>DW_TAG_structure_type</li>
2745 <li>DW_TAG_subroutine_type</li>
2746 <li>DW_TAG_typedef</li>
2747 <li>DW_TAG_union_type</li>
2748 <li>DW_TAG_ptr_to_member_type</li>
2749 <li>DW_TAG_set_type</li>
2750 <li>DW_TAG_subrange_type</li>
2751 <li>DW_TAG_base_type</li>
2752 <li>DW_TAG_const_type</li>
2753 <li>DW_TAG_constant</li>
2754 <li>DW_TAG_file_type</li>
2755 <li>DW_TAG_namelist</li>
2756 <li>DW_TAG_packed_type</li>
2757 <li>DW_TAG_volatile_type</li>
2758 <li>DW_TAG_restrict_type</li>
2759 <li>DW_TAG_interface_type</li>
2760 <li>DW_TAG_unspecified_type</li>
2761 <li>DW_TAG_shared_type</li>
2762</ul>
2763<p>Only entries with a DW_AT_name attribute are included, and the entry must
2764 not be a forward declaration (DW_AT_declaration attribute with a non-zero value).
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2765 For example, using the following code:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2766<div class="doc_code">
2767<pre>
2768int main ()
2769{
2770 int *b = 0;
2771 return *b;
2772}
2773</pre>
2774</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2775<p>We get a few type DIEs:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2776<div class="doc_code">
2777<pre>
27780x00000067: TAG_base_type [5]
2779 AT_encoding( DW_ATE_signed )
2780 AT_name( "int" )
2781 AT_byte_size( 0x04 )
2782
27830x0000006e: TAG_pointer_type [6]
2784 AT_type( {0x00000067} ( int ) )
2785 AT_byte_size( 0x08 )
2786</pre>
2787</div>
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2788<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]2789
2790<p>".apple_namespaces" section should contain all DW_TAG_namespace DIEs. If
2791 we run into a namespace that has no name this is an anonymous namespace,
2792 and the name should be output as "(anonymous namespace)" (without the quotes).
2793 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]2794 C++ library that demangles mangled names.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2795</div>
2796
2797<!-- ======================================================================= -->
2798<h4>
2799 <a name="acceltableextensions">Language Extensions and File Format Changes</a>
2800</h4>
2801<!-- ======================================================================= -->
2802<div>
2803<h5>Objective-C Extensions</h5>
2804<p>".apple_objc" section should contain all DW_TAG_subprogram DIEs for an
2805 Objective-C class. The name used in the hash table is the name of the
2806 Objective-C class itself. If the Objective-C class has a category, then an
2807 entry is made for both the class name without the category, and for the class
2808 name with the category. So if we have a DIE at offset 0x1234 with a name
2809 of method "-[NSString(my_additions) stringWithSpecialString:]", we would add
2810 an entry for "NSString" that points to DIE 0x1234, and an entry for
2811 "NSString(my_additions)" that points to 0x1234. This allows us to quickly
2812 track down all Objective-C methods for an Objective-C class when doing
2813 expressions. It is needed because of the dynamic nature of Objective-C where
2814 anyone can add methods to a class. The DWARF for Objective-C methods is also
2815 emitted differently from C++ classes where the methods are not usually
2816 contained in the class definition, they are scattered about across one or more
2817 compile units. Categories can also be defined in different shared libraries.
2818 So we need to be able to quickly find all of the methods and class functions
2819 given the Objective-C class name, or quickly find all methods and class
2820 functions for a class + category name. This table does not contain any selector
2821 names, it just maps Objective-C class names (or class names + category) to all
2822 of the methods and class functions. The selectors are added as function
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2823 basenames in the .debug_names section.</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2824
2825<p>In the ".apple_names" section for Objective-C functions, the full name is the
2826 entire function name with the brackets ("-[NSString stringWithCString:]") and the
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2827 basename is the selector only ("stringWithCString:").</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2828
2829<h5>Mach-O Changes</h5>
2830<p>The sections names for the apple hash tables are for non mach-o files. For
2831 mach-o files, the sections should be contained in the "__DWARF" segment with
Bill Wendling88a68082012-03-06 08:59:13 +0000[diff] [blame]2832 names as follows:</p>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2833<ul>
2834 <li>".apple_names" -> "__apple_names"</li>
2835 <li>".apple_types" -> "__apple_types"</li>
2836 <li>".apple_namespaces" -> "__apple_namespac" (16 character limit)</li>
2837 <li> ".apple_objc" -> "__apple_objc"</li>
2838</ul>
2839</div>
2840</div>
NAKAMURA Takumi9c55f592012-03-27 11:25:16 +0000[diff] [blame]2841</div>
Eric Christopher25e63292012-03-06 02:25:38 +0000[diff] [blame]2842
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2843<!-- *********************************************************************** -->
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2844
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2845<hr>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2846<address>
2847 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]2848 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2849 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]2850 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]2851
2852 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
NAKAMURA Takumib9a33632011-04-09 02:13:37 +0000[diff] [blame]2853 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2854 Last modified: $Date$
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]2855</address>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]2856
2857</body>
2858</html>