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5 <title>Source Level Debugging with LLVM</title>
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8<body>
9
10<div class="doc_title">Source Level Debugging with LLVM</div>
11
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]12<table class="layout" style="width:100%">
13 <tr class="layout">
14 <td class="left">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]15<ul>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]16 <li><a href="#introduction">Introduction</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]17 <ol>
18 <li><a href="#phil">Philosophy behind LLVM debugging information</a></li>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]19 <li><a href="#consumers">Debug information consumers</a></li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]20 <li><a href="#debugopt">Debugging optimized code</a></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]21 </ol></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]22 <li><a href="#format">Debugging information format</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]23 <ol>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]24 <li><a href="#debug_info_descriptors">Debug information descriptors</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]25 <ul>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]26 <li><a href="#format_anchors">Anchor descriptors</a></li>
27 <li><a href="#format_compile_units">Compile unit descriptors</a></li>
28 <li><a href="#format_global_variables">Global variable descriptors</a></li>
29 <li><a href="#format_subprograms">Subprogram descriptors</a></li>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]30 <li><a href="#format_blocks">Block descriptors</a></li>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]31 <li><a href="#format_basic_type">Basic type descriptors</a></li>
32 <li><a href="#format_derived_type">Derived type descriptors</a></li>
33 <li><a href="#format_composite_type">Composite type descriptors</a></li>
34 <li><a href="#format_subrange">Subrange descriptors</a></li>
35 <li><a href="#format_enumeration">Enumerator descriptors</a></li>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]36 <li><a href="#format_variables">Local variables</a></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]37 </ul></li>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]38 <li><a href="#format_common_intrinsics">Debugger intrinsic functions</a>
39 <ul>
40 <li><a href="#format_common_stoppoint">llvm.dbg.stoppoint</a></li>
41 <li><a href="#format_common_func_start">llvm.dbg.func.start</a></li>
42 <li><a href="#format_common_region_start">llvm.dbg.region.start</a></li>
43 <li><a href="#format_common_region_end">llvm.dbg.region.end</a></li>
44 <li><a href="#format_common_declare">llvm.dbg.declare</a></li>
45 </ul></li>
46 <li><a href="#format_common_stoppoints">Representing stopping points in the
47 source program</a></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]48 </ol></li>
49 <li><a href="#ccxx_frontend">C/C++ front-end specific debug information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]50 <ol>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]51 <li><a href="#ccxx_compile_units">C/C++ source file information</a></li>
52 <li><a href="#ccxx_global_variable">C/C++ global variable information</a></li>
53 <li><a href="#ccxx_subprogram">C/C++ function information</a></li>
54 <li><a href="#ccxx_basic_types">C/C++ basic types</a></li>
55 <li><a href="#ccxx_derived_types">C/C++ derived types</a></li>
56 <li><a href="#ccxx_composite_types">C/C++ struct/union types</a></li>
57 <li><a href="#ccxx_enumeration_types">C/C++ enumeration types</a></li>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]58 </ol></li>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]59</ul>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]60</td>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]61<td class="right">
Misha Brukmane849a1a2004-05-12 21:26:16 +0000[diff] [blame]62<img src="img/venusflytrap.jpg" alt="A leafy and green bug eater" width="247"
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]63height="369">
64</td>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]65</tr></table>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]66
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]67<div class="doc_author">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]68 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
Jim Laskeyc760a922007-03-14 19:32:21 +0000[diff] [blame]69 and <a href="mailto:jlaskey@mac.com">Jim Laskey</a></p>
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]70</div>
71
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]72
73<!-- *********************************************************************** -->
Misha Brukman94218a72004-12-09 20:27:37 +0000[diff] [blame]74<div class="doc_section"><a name="introduction">Introduction</a></div>
75<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]76
77<div class="doc_text">
78
79<p>This document is the central repository for all information pertaining to
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]80debug information in LLVM. It describes the <a href="#format">actual format
81that the LLVM debug information</a> takes, which is useful for those interested
82in creating front-ends or dealing directly with the information. Further, this
83document provides specifc examples of what debug information for C/C++.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]84
85</div>
86
87<!-- ======================================================================= -->
88<div class="doc_subsection">
89 <a name="phil">Philosophy behind LLVM debugging information</a>
90</div>
91
92<div class="doc_text">
93
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]94<p>The idea of the LLVM debugging information is to capture how the important
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]95pieces of the source-language's Abstract Syntax Tree map onto LLVM code.
96Several design aspects have shaped the solution that appears here. The
97important ones are:</p>
98
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]99<ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]100<li>Debugging information should have very little impact on the rest of the
101compiler. No transformations, analyses, or code generators should need to be
102modified because of debugging information.</li>
103
104<li>LLVM optimizations should interact in <a href="#debugopt">well-defined and
105easily described ways</a> with the debugging information.</li>
106
107<li>Because LLVM is designed to support arbitrary programming languages,
108LLVM-to-LLVM tools should not need to know anything about the semantics of the
109source-level-language.</li>
110
111<li>Source-level languages are often <b>widely</b> different from one another.
112LLVM should not put any restrictions of the flavor of the source-language, and
113the debugging information should work with any language.</li>
114
115<li>With code generator support, it should be possible to use an LLVM compiler
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]116to compile a program to native machine code and standard debugging formats.
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]117This allows compatibility with traditional machine-code level debuggers, like
118GDB or DBX.</li>
119
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]120</ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]121
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]122<p>The approach used by the LLVM implementation is to use a small set of <a
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]123href="#format_common_intrinsics">intrinsic functions</a> to define a mapping
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]124between LLVM program objects and the source-level objects. The description of
125the source-level program is maintained in LLVM global variables in an <a
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]126href="#ccxx_frontend">implementation-defined format</a> (the C/C++ front-end
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]127currently uses working draft 7 of the <a
128href="http://www.eagercon.com/dwarf/dwarf3std.htm">Dwarf 3 standard</a>).</p>
129
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]130<p>When a program is being debugged, a debugger interacts with the user and
131turns the stored debug information into source-language specific information.
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]132As such, a debugger must be aware of the source-language, and is thus tied to
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]133a specific language of family of languages.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]134
135</div>
136
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]137<!-- ======================================================================= -->
138<div class="doc_subsection">
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]139 <a name="consumers">Debug information consumers</a>
140</div>
141
142<div class="doc_text">
143<p>The role of debug information is to provide meta information normally
144stripped away during the compilation process. This meta information provides an
145llvm user a relationship between generated code and the original program source
146code.</p>
147
148<p>Currently, debug information is consumed by the DwarfWriter to produce dwarf
149information used by the gdb debugger. Other targets could use the same
150information to produce stabs or other debug forms.</p>
151
152<p>It would also be reasonable to use debug information to feed profiling tools
153for analysis of generated code, or, tools for reconstructing the original source
154from generated code.</p>
155
156<p>TODO - expound a bit more.</p>
157
158</div>
159
160<!-- ======================================================================= -->
161<div class="doc_subsection">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]162 <a name="debugopt">Debugging optimized code</a>
163</div>
164
165<div class="doc_text">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]166
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]167<p>An extremely high priority of LLVM debugging information is to make it
168interact well with optimizations and analysis. In particular, the LLVM debug
169information provides the following guarantees:</p>
170
171<ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]172
173<li>LLVM debug information <b>always provides information to accurately read the
174source-level state of the program</b>, regardless of which LLVM optimizations
175have been run, and without any modification to the optimizations themselves.
176However, some optimizations may impact the ability to modify the current state
177of the program with a debugger, such as setting program variables, or calling
178function that have been deleted.</li>
179
180<li>LLVM optimizations gracefully interact with debugging information. If they
181are not aware of debug information, they are automatically disabled as necessary
182in the cases that would invalidate the debug info. This retains the LLVM
183features making it easy to write new transformations.</li>
184
185<li>As desired, LLVM optimizations can be upgraded to be aware of the LLVM
186debugging information, allowing them to update the debugging information as they
187perform aggressive optimizations. This means that, with effort, the LLVM
188optimizers could optimize debug code just as well as non-debug code.</li>
189
190<li>LLVM debug information does not prevent many important optimizations from
191happening (for example inlining, basic block reordering/merging/cleanup, tail
192duplication, etc), further reducing the amount of the compiler that eventually
193is "aware" of debugging information.</li>
194
195<li>LLVM debug information is automatically optimized along with the rest of the
196program, using existing facilities. For example, duplicate information is
197automatically merged by the linker, and unused information is automatically
198removed.</li>
199
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]200</ul>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]201
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]202<p>Basically, the debug information allows you to compile a program with
203"<tt>-O0 -g</tt>" and get full debug information, allowing you to arbitrarily
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]204modify the program as it executes from a debugger. Compiling a program with
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]205"<tt>-O3 -g</tt>" gives you full debug information that is always available and
206accurate for reading (e.g., you get accurate stack traces despite tail call
207elimination and inlining), but you might lose the ability to modify the program
208and call functions where were optimized out of the program, or inlined away
209completely.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]210
211</div>
212
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]213<!-- *********************************************************************** -->
214<div class="doc_section">
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]215 <a name="format">Debugging information format</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]216</div>
217<!-- *********************************************************************** -->
218
219<div class="doc_text">
220
221<p>LLVM debugging information has been carefully designed to make it possible
222for the optimizer to optimize the program and debugging information without
223necessarily having to know anything about debugging information. In particular,
224the global constant merging pass automatically eliminates duplicated debugging
225information (often caused by header files), the global dead code elimination
226pass automatically deletes debugging information for a function if it decides to
227delete the function, and the linker eliminates debug information when it merges
228<tt>linkonce</tt> functions.</p>
229
230<p>To do this, most of the debugging information (descriptors for types,
231variables, functions, source files, etc) is inserted by the language front-end
232in the form of LLVM global variables. These LLVM global variables are no
233different from any other global variables, except that they have a web of LLVM
234intrinsic functions that point to them. If the last references to a particular
235piece of debugging information are deleted (for example, by the
236<tt>-globaldce</tt> pass), the extraneous debug information will automatically
237become dead and be removed by the optimizer.</p>
238
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]239<p>Debug information is designed to be agnostic about the target debugger and
240debugging information representation (e.g. DWARF/Stabs/etc). It uses a generic
241machine debug information pass to decode the information that represents
242variables, types, functions, namespaces, etc: this allows for arbitrary
243source-language semantics and type-systems to be used, as long as there is a
244module written for the target debugger to interpret the information. In
245addition, debug global variables are declared in the <tt>"llvm.metadata"</tt>
246section. All values declared in this section are stripped away after target
247debug information is constructed and before the program object is emitted.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]248
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]249<p>To provide basic functionality, the LLVM debugger does have to make some
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]250assumptions about the source-level language being debugged, though it keeps
251these to a minimum. The only common features that the LLVM debugger assumes
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]252exist are <a href="#format_compile_units">source files</a>, and <a
253href="#format_global_variables">program objects</a>. These abstract objects are
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]254used by a debugger to form stack traces, show information about local
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]255variables, etc.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]256
257<p>This section of the documentation first describes the representation aspects
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]258common to any source-language. The <a href="#ccxx_frontend">next section</a>
259describes the data layout conventions used by the C and C++ front-ends.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]260
261</div>
262
263<!-- ======================================================================= -->
264<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]265 <a name="debug_info_descriptors">Debug information descriptors</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]266</div>
267
268<div class="doc_text">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]269<p>In consideration of the complexity and volume of debug information, LLVM
270provides a specification for well formed debug global variables. The constant
271value of each of these globals is one of a limited set of structures, known as
272debug descriptors.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]273
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]274<p>Consumers of LLVM debug information expect the descriptors for program
275objects to start in a canonical format, but the descriptors can include
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]276additional information appended at the end that is source-language specific. All
277LLVM debugging information is versioned, allowing backwards compatibility in the
278case that the core structures need to change in some way. Also, all debugging
279information objects start with a tag to indicate what type of object it is. The
280source-language is allowed to define its own objects, by using unreserved tag
281numbers. We recommend using with tags in the range 0x1000 thru 0x2000 (there is
282a defined enum DW_TAG_user_base = 0x1000.)</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]283
Jim Laskey44c3b9f2007-01-26 21:22:28 +0000[diff] [blame]284<p>The fields of debug descriptors used internally by LLVM (MachineModuleInfo)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]285are restricted to only the simple data types <tt>int</tt>, <tt>uint</tt>,
286<tt>bool</tt>, <tt>float</tt>, <tt>double</tt>, <tt>sbyte*</tt> and <tt> { }*
287</tt>. References to arbitrary values are handled using a <tt> { }* </tt> and a
288cast to <tt> { }* </tt> expression; typically references to other field
289descriptors, arrays of descriptors or global variables.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]290
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]291<pre>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]292 %llvm.dbg.object.type = type {
293 uint, ;; A tag
294 ...
295 }
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]296</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]297
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]298<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
299<tt>uint</tt> containing a tag value identifying the content of the descriptor.
300The remaining fields are specific to the descriptor. The values of tags are
301loosely bound to the tag values of Dwarf information entries. However, that
302does not restrict the use of the information supplied to Dwarf targets. To
303facilitate versioning of debug information, the tag is augmented with the
Jim Laskey76a015e2006-06-16 13:45:38 +0000[diff] [blame]304current debug version (LLVMDebugVersion = 4 << 16 or 0x40000 or 262144.)</a></p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]305
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]306<p>The details of the various descriptors follow.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]307
308</div>
309
310<!-- ======================================================================= -->
311<div class="doc_subsubsection">
312 <a name="format_anchors">Anchor descriptors</a>
313</div>
314
315<div class="doc_text">
316
317<pre>
318 %<a href="#format_anchors">llvm.dbg.anchor.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]319 uint, ;; Tag = 0 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]320 uint ;; Tag of descriptors grouped by the anchor
321 }
322</pre>
323
324<p>One important aspect of the LLVM debug representation is that it allows the
325LLVM debugger to efficiently index all of the global objects without having the
326scan the program. To do this, all of the global objects use "anchor"
327descriptors with designated names. All of the global objects of a particular
328type (e.g., compile units) contain a pointer to the anchor. This pointer allows
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]329a debugger to use def-use chains to find all global objects of that type.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]330
331<p>The following names are recognized as anchors by LLVM:</p>
332
333<pre>
334 %<a href="#format_compile_units">llvm.dbg.compile_units</a> = linkonce constant %<a href="#format_anchors">llvm.dbg.anchor.type</a> { uint 0, uint 17 } ;; DW_TAG_compile_unit
335 %<a href="#format_global_variables">llvm.dbg.global_variables</a> = linkonce constant %<a href="#format_anchors">llvm.dbg.anchor.type</a> { uint 0, uint 52 } ;; DW_TAG_variable
336 %<a href="#format_subprograms">llvm.dbg.subprograms</a> = linkonce constant %<a href="#format_anchors">llvm.dbg.anchor.type</a> { uint 0, uint 46 } ;; DW_TAG_subprogram
337</pre>
338
339<p>Using anchors in this way (where the compile unit descriptor points to the
340anchors, as opposed to having a list of compile unit descriptors) allows for the
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]341standard dead global elimination and merging passes to automatically remove
342unused debugging information. If the globals were kept track of through lists,
343there would always be an object pointing to the descriptors, thus would never be
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]344deleted.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]345
346</div>
347
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]348<!-- ======================================================================= -->
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]349<div class="doc_subsubsection">
350 <a name="format_compile_units">Compile unit descriptors</a>
351</div>
352
353<div class="doc_text">
354
355<pre>
356 %<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]357 uint, ;; Tag = 17 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_compile_unit)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]358 { }*, ;; Compile unit anchor = cast = (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_units</a> to { }*)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]359 uint, ;; Dwarf language identifier (ex. DW_LANG_C89)
360 sbyte*, ;; Source file name
361 sbyte*, ;; Source file directory (includes trailing slash)
362 sbyte* ;; Producer (ex. "4.0.1 LLVM (LLVM research group)")
363 }
364</pre>
365
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]366<p>These descriptors contain a source language ID for the file (we use the Dwarf
3673.0 ID numbers, such as <tt>DW_LANG_C89</tt>, <tt>DW_LANG_C_plus_plus</tt>,
368<tt>DW_LANG_Cobol74</tt>, etc), three strings describing the filename, working
369directory of the compiler, and an identifier string for the compiler that
370produced it.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]371
372<p> Compile unit descriptors provide the root context for objects declared in a
373specific source file. Global variables and top level functions would be defined
374using this context. Compile unit descriptors also provide context for source
375line correspondence.</p>
376
377</div>
378
379<!-- ======================================================================= -->
380<div class="doc_subsubsection">
381 <a name="format_global_variables">Global variable descriptors</a>
382</div>
383
384<div class="doc_text">
385
386<pre>
387 %<a href="#format_global_variables">llvm.dbg.global_variable.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]388 uint, ;; Tag = 52 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_variable)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]389 { }*, ;; Global variable anchor = cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_global_variables">llvm.dbg.global_variables</a> to { }*),
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]390 { }*, ;; Reference to context descriptor
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]391 sbyte*, ;; Name
Jim Laskeyfe793812006-11-30 14:36:22 +0000[diff] [blame]392 sbyte*, ;; Display name (fully qualified C++ name)
393 sbyte*, ;; MIPS linkage name (for C++)
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]394 { }*, ;; Reference to compile unit where defined
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]395 uint, ;; Line number where defined
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]396 { }*, ;; Reference to type descriptor
397 bool, ;; True if the global is local to compile unit (static)
398 bool, ;; True if the global is defined in the compile unit (not extern)
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]399 { }* ;; Reference to the global variable
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]400 }
401</pre>
402
403<p>These descriptors provide debug information about globals variables. The
404provide details such as name, type and where the variable is defined.</p>
405
406</div>
407
408<!-- ======================================================================= -->
409<div class="doc_subsubsection">
410 <a name="format_subprograms">Subprogram descriptors</a>
411</div>
412
413<div class="doc_text">
414
415<pre>
416 %<a href="#format_subprograms">llvm.dbg.subprogram.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]417 uint, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subprogram)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]418 { }*, ;; Subprogram anchor = cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_subprograms">llvm.dbg.subprograms</a> to { }*),
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]419 { }*, ;; Reference to context descriptor
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]420 sbyte*, ;; Name
Jim Laskeyfe793812006-11-30 14:36:22 +0000[diff] [blame]421 sbyte*, ;; Display name (fully qualified C++ name)
422 sbyte*, ;; MIPS linkage name (for C++)
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]423 { }*, ;; Reference to compile unit where defined
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]424 uint, ;; Line number where defined
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]425 { }*, ;; Reference to type descriptor
426 bool, ;; True if the global is local to compile unit (static)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]427 bool ;; True if the global is defined in the compile unit (not extern)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]428 }
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]429</pre>
430
431<p>These descriptors provide debug information about functions, methods and
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]432subprograms. They provide details such as name, return types and the source
433location where the subprogram is defined.</p>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]434
435</div>
436<!-- ======================================================================= -->
437<div class="doc_subsubsection">
438 <a name="format_blocks">Block descriptors</a>
439</div>
440
441<div class="doc_text">
442
443<pre>
444 %<a href="#format_blocks">llvm.dbg.block</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]445 uint, ;; Tag = 13 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]446 { }* ;; Reference to context descriptor
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]447 }
448</pre>
449
450<p>These descriptors provide debug information about nested blocks within a
451subprogram. The array of member descriptors is used to define local variables
452and deeper nested blocks.</p>
453
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]454</div>
455
456<!-- ======================================================================= -->
457<div class="doc_subsubsection">
458 <a name="format_basic_type">Basic type descriptors</a>
459</div>
460
461<div class="doc_text">
462
463<pre>
464 %<a href="#format_basic_type">llvm.dbg.basictype.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]465 uint, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_base_type)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]466 { }*, ;; Reference to context (typically a compile unit)
467 sbyte*, ;; Name (may be "" for anonymous types)
468 { }*, ;; Reference to compile unit where defined (may be NULL)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]469 uint, ;; Line number where defined (may be 0)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]470 uint, ;; Size in bits
471 uint, ;; Alignment in bits
472 uint, ;; Offset in bits
473 uint ;; Dwarf type encoding
474 }
475</pre>
476
477<p>These descriptors define primitive types used in the code. Example int, bool
478and float. The context provides the scope of the type, which is usually the top
479level. Since basic types are not usually user defined the compile unit and line
480number can be left as NULL and 0. The size, alignment and offset are expressed
481in bits and can be 64 bit values. The alignment is used to round the offset
482when embedded in a <a href="#format_composite_type">composite type</a>
483(example to keep float doubles on 64 bit boundaries.) The offset is the bit
484offset if embedded in a <a href="#format_composite_type">composite
485type</a>.</p>
486
487<p>The type encoding provides the details of the type. The values are typically
488one of the following;</p>
489
490<pre>
491 DW_ATE_address = 1
492 DW_ATE_boolean = 2
493 DW_ATE_float = 4
494 DW_ATE_signed = 5
495 DW_ATE_signed_char = 6
496 DW_ATE_unsigned = 7
497 DW_ATE_unsigned_char = 8
498</pre>
499
500</div>
501
502<!-- ======================================================================= -->
503<div class="doc_subsubsection">
504 <a name="format_derived_type">Derived type descriptors</a>
505</div>
506
507<div class="doc_text">
508
509<pre>
510 %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> = type {
511 uint, ;; Tag (see below)
512 { }*, ;; Reference to context
513 sbyte*, ;; Name (may be "" for anonymous types)
514 { }*, ;; Reference to compile unit where defined (may be NULL)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]515 uint, ;; Line number where defined (may be 0)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]516 uint, ;; Size in bits
517 uint, ;; Alignment in bits
518 uint, ;; Offset in bits
519 { }* ;; Reference to type derived from
520 }
521</pre>
522
523<p>These descriptors are used to define types derived from other types. The
524value of the tag varies depending on the meaning. The following are possible
525tag values;</p>
526
527<pre>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]528 DW_TAG_formal_parameter = 5
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]529 DW_TAG_member = 13
530 DW_TAG_pointer_type = 15
531 DW_TAG_reference_type = 16
532 DW_TAG_typedef = 22
533 DW_TAG_const_type = 38
534 DW_TAG_volatile_type = 53
535 DW_TAG_restrict_type = 55
536</pre>
537
538<p> <tt>DW_TAG_member</tt> is used to define a member of a <a
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]539href="#format_composite_type">composite type</a> or <a
540href="#format_subprograms">subprogram</a>. The type of the member is the <a
541href="#format_derived_type">derived type</a>. <tt>DW_TAG_formal_parameter</tt>
542is used to define a member which is a formal argument of a subprogram.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]543
544<p><tt>DW_TAG_typedef</tt> is used to
545provide a name for the derived type.</p>
546
547<p><tt>DW_TAG_pointer_type</tt>,
548<tt>DW_TAG_reference_type</tt>, <tt>DW_TAG_const_type</tt>,
549<tt>DW_TAG_volatile_type</tt> and <tt>DW_TAG_restrict_type</tt> are used to
550qualify the <a href="#format_derived_type">derived type</a>. </p>
551
552<p><a href="#format_derived_type">Derived type</a> location can be determined
553from the compile unit and line number. The size, alignment and offset are
554expressed in bits and can be 64 bit values. The alignment is used to round the
555offset when embedded in a <a href="#format_composite_type">composite type</a>
556(example to keep float doubles on 64 bit boundaries.) The offset is the bit
557offset if embedded in a <a href="#format_composite_type">composite
558type</a>.</p>
559
560<p>Note that the <tt>void *</tt> type is expressed as a
561<tt>llvm.dbg.derivedtype.type</tt> with tag of <tt>DW_TAG_pointer_type</tt> and
562NULL derived type.</p>
563
564</div>
565
566<!-- ======================================================================= -->
567<div class="doc_subsubsection">
568 <a name="format_composite_type">Composite type descriptors</a>
569</div>
570
571<div class="doc_text">
572
573<pre>
574 %<a href="#format_composite_type">llvm.dbg.compositetype.type</a> = type {
575 uint, ;; Tag (see below)
576 { }*, ;; Reference to context
577 sbyte*, ;; Name (may be "" for anonymous types)
578 { }*, ;; Reference to compile unit where defined (may be NULL)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]579 uint, ;; Line number where defined (may be 0)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]580 uint, ;; Size in bits
581 uint, ;; Alignment in bits
582 uint, ;; Offset in bits
583 { }* ;; Reference to array of member descriptors
584 }
585</pre>
586
587<p>These descriptors are used to define types that are composed of 0 or more
588elements. The value of the tag varies depending on the meaning. The following
589are possible tag values;</p>
590
591<pre>
592 DW_TAG_array_type = 1
593 DW_TAG_enumeration_type = 4
594 DW_TAG_structure_type = 19
595 DW_TAG_union_type = 23
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]596 DW_TAG_vector_type = 259
Jim Laskey094ee722006-06-20 21:13:20 +0000[diff] [blame]597 DW_TAG_subroutine_type = 46
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]598 DW_TAG_inheritance = 26
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]599</pre>
600
Jim Laskeyf8a01a92006-06-15 20:51:43 +0000[diff] [blame]601<p>The vector flag indicates that an array type is a native packed vector.</p>
602
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]603<p>The members of array types (tag = <tt>DW_TAG_array_type</tt>) or vector types
604(tag = <tt>DW_TAG_vector_type</tt>) are <a href="#format_subrange">subrange
605descriptors</a>, each representing the range of subscripts at that level of
606indexing.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]607
608<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
609<a href="#format_enumeration">enumerator descriptors</a>, each representing the
610definition of enumeration value
611for the set.</p>
612
613<p>The members of structure (tag = <tt>DW_TAG_structure_type</tt>) or union (tag
614= <tt>DW_TAG_union_type</tt>) types are any one of the <a
615href="#format_basic_type">basic</a>, <a href="#format_derived_type">derived</a>
616or <a href="#format_composite_type">composite</a> type descriptors, each
617representing a field member of the structure or union.</p>
618
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]619<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
620provide information about base classes, static members and member functions. If
621a member is a <a href="#format_derived_type">derived type descriptor</a> and has
622a tag of <tt>DW_TAG_inheritance</tt>, then the type represents a base class. If
623the member of is a <a href="#format_global_variables">global variable
624descriptor</a> then it represents a static member. And, if the member is a <a
625href="#format_subprograms">subprogram descriptor</a> then it represents a member
626function. For static members and member functions, <tt>getName()</tt> returns
627the members link or the C++ mangled name. <tt>getDisplayName()</tt> the
628simplied version of the name.</p>
629
Jim Laskeyb329fe12006-06-21 11:08:10 +0000[diff] [blame]630<p>The first member of subroutine (tag = <tt>DW_TAG_subroutine_type</tt>)
631type elements is the return type for the subroutine. The remaining
Jim Laskey094ee722006-06-20 21:13:20 +0000[diff] [blame]632elements are the formal arguments to the subroutine.</p>
633
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]634<p><a href="#format_composite_type">Composite type</a> location can be
635determined from the compile unit and line number. The size, alignment and
636offset are expressed in bits and can be 64 bit values. The alignment is used to
637round the offset when embedded in a <a href="#format_composite_type">composite
638type</a> (as an example, to keep float doubles on 64 bit boundaries.) The offset
639is the bit offset if embedded in a <a href="#format_composite_type">composite
640type</a>.</p>
641
642</div>
643
644<!-- ======================================================================= -->
645<div class="doc_subsubsection">
646 <a name="format_subrange">Subrange descriptors</a>
647</div>
648
649<div class="doc_text">
650
651<pre>
652 %<a href="#format_subrange">llvm.dbg.subrange.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]653 uint, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]654 uint, ;; Low value
655 uint ;; High value
656 }
657</pre>
658
659<p>These descriptors are used to define ranges of array subscripts for an array
660<a href="#format_composite_type">composite type</a>. The low value defines the
661lower bounds typically zero for C/C++. The high value is the upper bounds.
662Values are 64 bit. High - low + 1 is the size of the array. If
663low == high the array will be unbounded.</p>
664
665</div>
666
667<!-- ======================================================================= -->
668<div class="doc_subsubsection">
669 <a name="format_enumeration">Enumerator descriptors</a>
670</div>
671
672<div class="doc_text">
673
674<pre>
675 %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]676 uint, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_enumerator)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]677 sbyte*, ;; Name
678 uint ;; Value
679 }
680</pre>
681
682<p>These descriptors are used to define members of an enumeration <a
683href="#format_composite_type">composite type</a>, it associates the name to the
684value.</p>
685
686</div>
687
688<!-- ======================================================================= -->
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]689<div class="doc_subsubsection">
690 <a name="format_variables">Local variables</a>
691</div>
692
693<div class="doc_text">
694<pre>
695 %<a href="#format_variables">llvm.dbg.variable.type</a> = type {
696 uint, ;; Tag (see below)
697 { }*, ;; Context
698 sbyte*, ;; Name
699 { }*, ;; Reference to compile unit where defined
700 uint, ;; Line number where defined
701 { }* ;; Type descriptor
702 }
703</pre>
704
705<p>These descriptors are used to define variables local to a sub program. The
706value of the tag depends on the usage of the variable;</p>
707
708<pre>
709 DW_TAG_auto_variable = 256
710 DW_TAG_arg_variable = 257
711 DW_TAG_return_variable = 258
712</pre>
713
714<p>An auto variable is any variable declared in the body of the function. An
715argument variable is any variable that appears as a formal argument to the
716function. A return variable is used to track the result of a function and has
717no source correspondent.</p>
718
Jim Laskey2d395d92006-03-24 09:20:27 +0000[diff] [blame]719<p>The context is either the subprogram or block where the variable is defined.
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]720Name the source variable name. Compile unit and line indicate where the
721variable was defined. Type descriptor defines the declared type of the
722variable.</p>
723
724</div>
725
726<!-- ======================================================================= -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]727<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]728 <a name="format_common_intrinsics">Debugger intrinsic functions</a>
729</div>
730
731<div class="doc_text">
732
733<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
734provide debug information at various points in generated code.</p>
735
736</div>
737
738<!-- ======================================================================= -->
739<div class="doc_subsubsection">
740 <a name="format_common_stoppoint">llvm.dbg.stoppoint</a>
741</div>
742
743<div class="doc_text">
744<pre>
Jim Laskey108a6382006-03-23 17:58:46 +0000[diff] [blame]745 void %<a href="#format_common_stoppoint">llvm.dbg.stoppoint</a>( uint, uint, { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]746</pre>
747
748<p>This intrinsic is used to provide correspondence between the source file and
749the generated code. The first argument is the line number (base 1), second
Duncan Sands41783f02007-06-14 11:27:07 +0000[diff] [blame]750argument is the column number (0 if unknown) and the third argument the source
Jim Laskey108a6382006-03-23 17:58:46 +0000[diff] [blame]751<tt>%<a href="#format_compile_units">llvm.dbg.compile_unit</a>*</tt> cast to a
752<tt>{ }*</tt>. Code following a call to this intrinsic will have been defined
753in close proximity of the line, column and file. This information holds until
754the next call to <tt>%<a
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]755href="#format_common_stoppoint">lvm.dbg.stoppoint</a></tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]756
757</div>
758
759<!-- ======================================================================= -->
760<div class="doc_subsubsection">
761 <a name="format_common_func_start">llvm.dbg.func.start</a>
762</div>
763
764<div class="doc_text">
765<pre>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]766 void %<a href="#format_common_func_start">llvm.dbg.func.start</a>( { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]767</pre>
768
769<p>This intrinsic is used to link the debug information in <tt>%<a
Evan Cheng8e342502008-02-01 09:12:11 +0000[diff] [blame]770href="#format_subprograms">llvm.dbg.subprogram</a></tt> to the function. It
771defines the beginning of the function's declarative region (scope). It also
772implies a call to %<tt><a
773href="#format_common_stoppoint">llvm.dbg.stoppoint</a></tt> which defines a
774source line "stop point". The intrinsic should be called early in the function
775after the all the alloca instructions. It should be paired off with a closing
776<tt>%<a
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]777href="#format_common_region_end">llvm.dbg.region.end</a></tt>. The function's
778single argument is the <tt>%<a
779href="#format_subprograms">llvm.dbg.subprogram.type</a></tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]780
781</div>
782
783<!-- ======================================================================= -->
784<div class="doc_subsubsection">
785 <a name="format_common_region_start">llvm.dbg.region.start</a>
786</div>
787
788<div class="doc_text">
789<pre>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]790 void %<a href="#format_common_region_start">llvm.dbg.region.start</a>( { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]791</pre>
792
793<p>This intrinsic is used to define the beginning of a declarative scope (ex.
794block) for local language elements. It should be paired off with a closing
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]795<tt>%<a href="#format_common_region_end">llvm.dbg.region.end</a></tt>. The
796function's single argument is the <tt>%<a
797href="#format_blocks">llvm.dbg.block</a></tt> which is starting.</p>
798
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]799
800</div>
801
802<!-- ======================================================================= -->
803<div class="doc_subsubsection">
804 <a name="format_common_region_end">llvm.dbg.region.end</a>
805</div>
806
807<div class="doc_text">
808<pre>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]809 void %<a href="#format_common_region_end">llvm.dbg.region.end</a>( { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]810</pre>
811
812<p>This intrinsic is used to define the end of a declarative scope (ex. block)
813for local language elements. It should be paired off with an opening <tt>%<a
814href="#format_common_region_start">llvm.dbg.region.start</a></tt> or <tt>%<a
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]815href="#format_common_func_start">llvm.dbg.func.start</a></tt>. The function's
816single argument is either the <tt>%<a
817href="#format_blocks">llvm.dbg.block</a></tt> or the <tt>%<a
818href="#format_subprograms">llvm.dbg.subprogram.type</a></tt> which is
819ending.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]820
821</div>
822
823<!-- ======================================================================= -->
824<div class="doc_subsubsection">
825 <a name="format_common_declare">llvm.dbg.declare</a>
826</div>
827
828<div class="doc_text">
829<pre>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]830 void %<a href="#format_common_declare">llvm.dbg.declare</a>( { } *, { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]831</pre>
832
Jim Laskey2d395d92006-03-24 09:20:27 +0000[diff] [blame]833<p>This intrinsic provides information about a local element (ex. variable.) The
834first argument is the alloca for the variable, cast to a <tt>{ }*</tt>. The
835second argument is the <tt>%<a
836href="#format_variables">llvm.dbg.variable</a></tt> containing the description
837of the variable, also cast to a <tt>{ }*</tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]838
839</div>
840
841<!-- ======================================================================= -->
842<div class="doc_subsection">
843 <a name="format_common_stoppoints">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]844 Representing stopping points in the source program
845 </a>
846</div>
847
848<div class="doc_text">
849
850<p>LLVM debugger "stop points" are a key part of the debugging representation
851that allows the LLVM to maintain simple semantics for <a
852href="#debugopt">debugging optimized code</a>. The basic idea is that the
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]853front-end inserts calls to the <a
854href="#format_common_stoppoint">%<tt>llvm.dbg.stoppoint</tt></a> intrinsic
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]855function at every point in the program where a debugger should be able to
856inspect the program (these correspond to places a debugger stops when you
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]857"<tt>step</tt>" through it). The front-end can choose to place these as
858fine-grained as it would like (for example, before every subexpression
859evaluated), but it is recommended to only put them after every source statement
860that includes executable code.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]861
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]862<p>Using calls to this intrinsic function to demark legal points for the
863debugger to inspect the program automatically disables any optimizations that
864could potentially confuse debugging information. To non-debug-information-aware
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]865transformations, these calls simply look like calls to an external function,
866which they must assume to do anything (including reading or writing to any part
867of reachable memory). On the other hand, it does not impact many optimizations,
868such as code motion of non-trapping instructions, nor does it impact
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]869optimization of subexpressions, code duplication transformations, or basic-block
870reordering transformations.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]871
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]872</div>
873
874
875<!-- ======================================================================= -->
876<div class="doc_subsection">
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]877 <a name="format_common_lifetime">Object lifetimes and scoping</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]878</div>
879
880<div class="doc_text">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]881<p>In many languages, the local variables in functions can have their lifetime
882or scope limited to a subset of a function. In the C family of languages, for
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]883example, variables are only live (readable and writable) within the source block
884that they are defined in. In functional languages, values are only readable
885after they have been defined. Though this is a very obvious concept, it is also
886non-trivial to model in LLVM, because it has no notion of scoping in this sense,
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]887and does not want to be tied to a language's scoping rules.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]888
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]889<p>In order to handle this, the LLVM debug format uses the notion of "regions"
890of a function, delineated by calls to intrinsic functions. These intrinsic
891functions define new regions of the program and indicate when the region
892lifetime expires. Consider the following C fragment, for example:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]893
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]894<pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8951. void foo() {
8962. int X = ...;
8973. int Y = ...;
8984. {
8995. int Z = ...;
9006. ...
9017. }
9028. ...
9039. }
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]904</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]905
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]906<p>Compiled to LLVM, this function would be represented like this:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]907
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]908<pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]909void %foo() {
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]910entry:
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]911 %X = alloca int
912 %Y = alloca int
913 %Z = alloca int
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]914
915 ...
916
917 call void %<a href="#format_common_func_start">llvm.dbg.func.start</a>( %<a href="#format_subprograms">llvm.dbg.subprogram.type</a>* %llvm.dbg.subprogram )
918
919 call void %<a href="#format_common_stoppoint">llvm.dbg.stoppoint</a>( uint 2, uint 2, %<a href="#format_compile_units">llvm.dbg.compile_unit</a>* %llvm.dbg.compile_unit )
920
921 call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %X, ...)
922 call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %Y, ...)
923
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]924 <i>;; Evaluate expression on line 2, assigning to X.</i>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]925
926 call void %<a href="#format_common_stoppoint">llvm.dbg.stoppoint</a>( uint 3, uint 2, %<a href="#format_compile_units">llvm.dbg.compile_unit</a>* %llvm.dbg.compile_unit )
927
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]928 <i>;; Evaluate expression on line 3, assigning to Y.</i>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]929
930 call void %<a href="#format_common_stoppoint">llvm.region.start</a>()
931 call void %<a href="#format_common_stoppoint">llvm.dbg.stoppoint</a>( uint 5, uint 4, %<a href="#format_compile_units">llvm.dbg.compile_unit</a>* %llvm.dbg.compile_unit )
932 call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %X, ...)
933
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]934 <i>;; Evaluate expression on line 5, assigning to Z.</i>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]935
936 call void %<a href="#format_common_stoppoint">llvm.dbg.stoppoint</a>( uint 7, uint 2, %<a href="#format_compile_units">llvm.dbg.compile_unit</a>* %llvm.dbg.compile_unit )
937 call void %<a href="#format_common_region_end">llvm.region.end</a>()
938
939 call void %<a href="#format_common_stoppoint">llvm.dbg.stoppoint</a>( uint 9, uint 2, %<a href="#format_compile_units">llvm.dbg.compile_unit</a>* %llvm.dbg.compile_unit )
940
941 call void %<a href="#format_common_region_end">llvm.region.end</a>()
942
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]943 ret void
944}
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]945</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]946
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]947<p>This example illustrates a few important details about the LLVM debugging
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]948information. In particular, it shows how the various intrinsics are applied
949together to allow a debugger to analyze the relationship between statements,
950variable definitions, and the code used to implement the function.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]951
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]952<p>The first intrinsic <tt>%<a
953href="#format_common_func_start">llvm.dbg.func.start</a></tt> provides
954a link with the <a href="#format_subprograms">subprogram descriptor</a>
955containing the details of this function. This call also defines the beginning
956of the function region, bounded by the <tt>%<a
957href="#format_common_region_end">llvm.region.end</a></tt> at the end of
958the function. This region is used to bracket the lifetime of variables declared
959within. For a function, this outer region defines a new stack frame whose
960lifetime ends when the region is ended.</p>
961
962<p>It is possible to define inner regions for short term variables by using the
963%<a href="#format_common_stoppoint"><tt>llvm.region.start</tt></a> and <a
964href="#format_common_region_end"><tt>%llvm.region.end</tt></a> to bound a
965region. The inner region in this example would be for the block containing the
966declaration of Z.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]967
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]968<p>Using regions to represent the boundaries of source-level functions allow
969LLVM interprocedural optimizations to arbitrarily modify LLVM functions without
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]970having to worry about breaking mapping information between the LLVM code and the
971and source-level program. In particular, the inliner requires no modification
972to support inlining with debugging information: there is no explicit correlation
973drawn between LLVM functions and their source-level counterparts (note however,
974that if the inliner inlines all instances of a non-strong-linkage function into
975its caller that it will not be possible for the user to manually invoke the
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]976inlined function from a debugger).</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]977
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]978<p>Once the function has been defined, the <a
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]979href="#format_common_stoppoint"><tt>stopping point</tt></a> corresponding to
980line #2 (column #2) of the function is encountered. At this point in the
981function, <b>no</b> local variables are live. As lines 2 and 3 of the example
982are executed, their variable definitions are introduced into the program using
983%<a href="#format_common_declare"><tt>llvm.dbg.declare</tt></a>, without the
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]984need to specify a new region. These variables do not require new regions to be
985introduced because they go out of scope at the same point in the program: line
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]9869.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]987
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]988<p>In contrast, the <tt>Z</tt> variable goes out of scope at a different time,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]989on line 7. For this reason, it is defined within the inner region, which kills
990the availability of <tt>Z</tt> before the code for line 8 is executed. In this
991way, regions can support arbitrary source-language scoping rules, as long as
992they can only be nested (ie, one scope cannot partially overlap with a part of
993another scope).</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]994
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]995<p>It is worth noting that this scoping mechanism is used to control scoping of
996all declarations, not just variable declarations. For example, the scope of a
Duncan Sands41783f02007-06-14 11:27:07 +0000[diff] [blame]997C++ using declaration is controlled with this and could change how name lookup is
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]998performed.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]999
1000</div>
1001
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1002
1003
1004<!-- *********************************************************************** -->
1005<div class="doc_section">
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1006 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1007</div>
Misha Brukman94218a72004-12-09 20:27:37 +0000[diff] [blame]1008<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1009
1010<div class="doc_text">
1011
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1012<p>The C and C++ front-ends represent information about the program in a format
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1013that is effectively identical to <a
1014href="http://www.eagercon.com/dwarf/dwarf3std.htm">Dwarf 3.0</a> in terms of
1015information content. This allows code generators to trivially support native
1016debuggers by generating standard dwarf information, and contains enough
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1017information for non-dwarf targets to translate it as needed.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1018
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1019<p>This section describes the forms used to represent C and C++ programs. Other
1020languages could pattern themselves after this (which itself is tuned to
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1021representing programs in the same way that Dwarf 3 does), or they could choose
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1022to provide completely different forms if they don't fit into the Dwarf model.
1023As support for debugging information gets added to the various LLVM
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1024source-language front-ends, the information used should be documented here.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1025
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1026<p>The following sections provide examples of various C/C++ constructs and the
1027debug information that would best describe those constructs.</p>
1028
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1029</div>
1030
1031<!-- ======================================================================= -->
1032<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1033 <a name="ccxx_compile_units">C/C++ source file information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1034</div>
1035
1036<div class="doc_text">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1037
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1038<p>Given the source files "MySource.cpp" and "MyHeader.h" located in the
1039directory "/Users/mine/sources", the following code;</p>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1040
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1041<pre>
1042#include "MyHeader.h"
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1043
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1044int main(int argc, char *argv[]) {
1045 return 0;
1046}
1047</pre>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1048
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1049<p>a C/C++ front-end would generate the following descriptors;</p>
1050
1051<pre>
1052...
1053;;
1054;; Define types used. In this case we need one for compile unit anchors and one
1055;; for compile units.
1056;;
1057%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
1058%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = type { uint, { }*, uint, uint, sbyte*, sbyte*, sbyte* }
1059...
1060;;
1061;; Define the anchor for compile units. Note that the second field of the
1062;; anchor is 17, which is the same as the tag for compile units
1063;; (17 = DW_TAG_compile_unit.)
1064;;
1065%<a href="#format_compile_units">llvm.dbg.compile_units</a> = linkonce constant %<a href="#format_anchors">llvm.dbg.anchor.type</a> { uint 0, uint 17 }, section "llvm.metadata"
1066
1067;;
1068;; Define the compile unit for the source file "/Users/mine/sources/MySource.cpp".
1069;;
1070%<a href="#format_compile_units">llvm.dbg.compile_unit1</a> = internal constant %<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1071 uint add(uint 17, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1072 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_units</a> to { }*),
1073 uint 1,
1074 uint 1,
1075 sbyte* getelementptr ([13 x sbyte]* %str1, int 0, int 0),
1076 sbyte* getelementptr ([21 x sbyte]* %str2, int 0, int 0),
1077 sbyte* getelementptr ([33 x sbyte]* %str3, int 0, int 0) }, section "llvm.metadata"
1078
1079;;
1080;; Define the compile unit for the header file "/Users/mine/sources/MyHeader.h".
1081;;
1082%<a href="#format_compile_units">llvm.dbg.compile_unit2</a> = internal constant %<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1083 uint add(uint 17, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1084 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_units</a> to { }*),
1085 uint 1,
1086 uint 1,
1087 sbyte* getelementptr ([11 x sbyte]* %str4, int 0, int 0),
1088 sbyte* getelementptr ([21 x sbyte]* %str2, int 0, int 0),
1089 sbyte* getelementptr ([33 x sbyte]* %str3, int 0, int 0) }, section "llvm.metadata"
1090
1091;;
1092;; Define each of the strings used in the compile units.
1093;;
1094%str1 = internal constant [13 x sbyte] c"MySource.cpp\00", section "llvm.metadata";
1095%str2 = internal constant [21 x sbyte] c"/Users/mine/sources/\00", section "llvm.metadata";
1096%str3 = internal constant [33 x sbyte] c"4.0.1 LLVM (LLVM research group)\00", section "llvm.metadata";
1097%str4 = internal constant [11 x sbyte] c"MyHeader.h\00", section "llvm.metadata";
1098...
1099</pre>
1100
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1101</div>
1102
1103<!-- ======================================================================= -->
1104<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1105 <a name="ccxx_global_variable">C/C++ global variable information</a>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1106</div>
1107
1108<div class="doc_text">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1109
1110<p>Given an integer global variable declared as follows;</p>
1111
1112<pre>
1113int MyGlobal = 100;
1114</pre>
1115
1116<p>a C/C++ front-end would generate the following descriptors;</p>
1117
1118<pre>
1119;;
1120;; Define types used. One for global variable anchors, one for the global
1121;; variable descriptor, one for the global's basic type and one for the global's
1122;; compile unit.
1123;;
1124%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1125%<a href="#format_global_variables">llvm.dbg.global_variable.type</a> = type { uint, { }*, { }*, sbyte*, { }*, uint, { }*, bool, bool, { }*, uint }
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1126%<a href="#format_basic_type">llvm.dbg.basictype.type</a> = type { uint, { }*, sbyte*, { }*, int, uint, uint, uint, uint }
1127%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = ...
1128...
1129;;
1130;; Define the global itself.
1131;;
1132%MyGlobal = global int 100
1133...
1134;;
1135;; Define the anchor for global variables. Note that the second field of the
1136;; anchor is 52, which is the same as the tag for global variables
1137;; (52 = DW_TAG_variable.)
1138;;
1139%<a href="#format_global_variables">llvm.dbg.global_variables</a> = linkonce constant %<a href="#format_anchors">llvm.dbg.anchor.type</a> { uint 0, uint 52 }, section "llvm.metadata"
1140
1141;;
1142;; Define the global variable descriptor. Note the reference to the global
1143;; variable anchor and the global variable itself.
1144;;
1145%<a href="#format_global_variables">llvm.dbg.global_variable</a> = internal constant %<a href="#format_global_variables">llvm.dbg.global_variable.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1146 uint add(uint 52, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1147 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_global_variables">llvm.dbg.global_variables</a> to { }*),
1148 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1149 sbyte* getelementptr ([9 x sbyte]* %str1, int 0, int 0),
Jim Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame]1150 sbyte* getelementptr ([1 x sbyte]* %str2, int 0, int 0),
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1151 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1152 uint 1,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1153 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*),
1154 bool false,
1155 bool true,
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1156 { }* cast (int* %MyGlobal to { }*) }, section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1157
1158;;
1159;; Define the basic type of 32 bit signed integer. Note that since int is an
1160;; intrinsic type the source file is NULL and line 0.
1161;;
1162%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1163 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1164 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
Jim Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame]1165 sbyte* getelementptr ([4 x sbyte]* %str3, int 0, int 0),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1166 { }* null,
1167 int 0,
1168 uint 32,
1169 uint 32,
1170 uint 0,
1171 uint 5 }, section "llvm.metadata"
1172
1173;;
1174;; Define the names of the global variable and basic type.
1175;;
1176%str1 = internal constant [9 x sbyte] c"MyGlobal\00", section "llvm.metadata"
Jim Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame]1177%str2 = internal constant [1 x sbyte] c"\00", section "llvm.metadata"
1178%str3 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1179</pre>
1180
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1181</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1182
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1183<!-- ======================================================================= -->
1184<div class="doc_subsection">
1185 <a name="ccxx_subprogram">C/C++ function information</a>
1186</div>
1187
1188<div class="doc_text">
1189
1190<p>Given a function declared as follows;</p>
1191
1192<pre>
1193int main(int argc, char *argv[]) {
1194 return 0;
1195}
1196</pre>
1197
1198<p>a C/C++ front-end would generate the following descriptors;</p>
1199
1200<pre>
1201;;
1202;; Define types used. One for subprogram anchors, one for the subprogram
1203;; descriptor, one for the global's basic type and one for the subprogram's
1204;; compile unit.
1205;;
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]1206%<a href="#format_subprograms">llvm.dbg.subprogram.type</a> = type { uint, { }*, { }*, sbyte*, { }*, bool, bool }
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1207%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
1208%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = ...
1209
1210;;
1211;; Define the anchor for subprograms. Note that the second field of the
1212;; anchor is 46, which is the same as the tag for subprograms
1213;; (46 = DW_TAG_subprogram.)
1214;;
1215%<a href="#format_subprograms">llvm.dbg.subprograms</a> = linkonce constant %<a href="#format_anchors">llvm.dbg.anchor.type</a> { uint 0, uint 46 }, section "llvm.metadata"
1216
1217;;
1218;; Define the descriptor for the subprogram. TODO - more details.
1219;;
1220%<a href="#format_subprograms">llvm.dbg.subprogram</a> = internal constant %<a href="#format_subprograms">llvm.dbg.subprogram.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1221 uint add(uint 46, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1222 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_subprograms">llvm.dbg.subprograms</a> to { }*),
1223 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1224 sbyte* getelementptr ([5 x sbyte]* %str1, int 0, int 0),
Jim Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame]1225 sbyte* getelementptr ([1 x sbyte]* %str2, int 0, int 0),
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1226 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1227 uint 1,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1228 { }* null,
1229 bool false,
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]1230 bool true }, section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1231
1232;;
1233;; Define the name of the subprogram.
1234;;
1235%str1 = internal constant [5 x sbyte] c"main\00", section "llvm.metadata"
Jim Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame]1236%str2 = internal constant [1 x sbyte] c"\00", section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1237
1238;;
1239;; Define the subprogram itself.
1240;;
1241int %main(int %argc, sbyte** %argv) {
1242...
1243}
1244</pre>
1245
1246</div>
1247
1248<!-- ======================================================================= -->
1249<div class="doc_subsection">
1250 <a name="ccxx_basic_types">C/C++ basic types</a>
1251</div>
1252
1253<div class="doc_text">
1254
1255<p>The following are the basic type descriptors for C/C++ core types;</p>
1256
1257</div>
1258
1259<!-- ======================================================================= -->
1260<div class="doc_subsubsection">
1261 <a name="ccxx_basic_type_bool">bool</a>
1262</div>
1263
1264<div class="doc_text">
1265
1266<pre>
1267%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1268 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1269 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1270 sbyte* getelementptr ([5 x sbyte]* %str1, int 0, int 0),
1271 { }* null,
1272 int 0,
1273 uint 32,
1274 uint 32,
1275 uint 0,
1276 uint 2 }, section "llvm.metadata"
1277%str1 = internal constant [5 x sbyte] c"bool\00", section "llvm.metadata"
1278</pre>
1279
1280</div>
1281
1282<!-- ======================================================================= -->
1283<div class="doc_subsubsection">
1284 <a name="ccxx_basic_char">char</a>
1285</div>
1286
1287<div class="doc_text">
1288
1289<pre>
1290%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1291 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1292 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1293 sbyte* getelementptr ([5 x sbyte]* %str1, int 0, int 0),
1294 { }* null,
1295 int 0,
1296 uint 8,
1297 uint 8,
1298 uint 0,
1299 uint 6 }, section "llvm.metadata"
1300%str1 = internal constant [5 x sbyte] c"char\00", section "llvm.metadata"
1301</pre>
1302
1303</div>
1304
1305<!-- ======================================================================= -->
1306<div class="doc_subsubsection">
1307 <a name="ccxx_basic_unsigned_char">unsigned char</a>
1308</div>
1309
1310<div class="doc_text">
1311
1312<pre>
1313%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1314 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1315 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1316 sbyte* getelementptr ([14 x sbyte]* %str1, int 0, int 0),
1317 { }* null,
1318 int 0,
1319 uint 8,
1320 uint 8,
1321 uint 0,
1322 uint 8 }, section "llvm.metadata"
1323%str1 = internal constant [14 x sbyte] c"unsigned char\00", section "llvm.metadata"
1324</pre>
1325
1326</div>
1327
1328<!-- ======================================================================= -->
1329<div class="doc_subsubsection">
1330 <a name="ccxx_basic_short">short</a>
1331</div>
1332
1333<div class="doc_text">
1334
1335<pre>
1336%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1337 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1338 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1339 sbyte* getelementptr ([10 x sbyte]* %str1, int 0, int 0),
1340 { }* null,
1341 int 0,
1342 uint 16,
1343 uint 16,
1344 uint 0,
1345 uint 5 }, section "llvm.metadata"
1346%str1 = internal constant [10 x sbyte] c"short int\00", section "llvm.metadata"
1347</pre>
1348
1349</div>
1350
1351<!-- ======================================================================= -->
1352<div class="doc_subsubsection">
1353 <a name="ccxx_basic_unsigned_short">unsigned short</a>
1354</div>
1355
1356<div class="doc_text">
1357
1358<pre>
1359%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1360 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1361 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1362 sbyte* getelementptr ([19 x sbyte]* %str1, int 0, int 0),
1363 { }* null,
1364 int 0,
1365 uint 16,
1366 uint 16,
1367 uint 0,
1368 uint 7 }, section "llvm.metadata"
1369%str1 = internal constant [19 x sbyte] c"short unsigned int\00", section "llvm.metadata"
1370</pre>
1371
1372</div>
1373
1374<!-- ======================================================================= -->
1375<div class="doc_subsubsection">
1376 <a name="ccxx_basic_int">int</a>
1377</div>
1378
1379<div class="doc_text">
1380
1381<pre>
1382%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1383 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1384 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1385 sbyte* getelementptr ([4 x sbyte]* %str1, int 0, int 0),
1386 { }* null,
1387 int 0,
1388 uint 32,
1389 uint 32,
1390 uint 0,
1391 uint 5 }, section "llvm.metadata"
1392%str1 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
1393</pre>
1394
1395</div>
1396
1397<!-- ======================================================================= -->
1398<div class="doc_subsubsection">
1399 <a name="ccxx_basic_unsigned_int">unsigned int</a>
1400</div>
1401
1402<div class="doc_text">
1403
1404<pre>
1405%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1406 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1407 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1408 sbyte* getelementptr ([13 x sbyte]* %str1, int 0, int 0),
1409 { }* null,
1410 int 0,
1411 uint 32,
1412 uint 32,
1413 uint 0,
1414 uint 7 }, section "llvm.metadata"
1415%str1 = internal constant [13 x sbyte] c"unsigned int\00", section "llvm.metadata"
1416</pre>
1417
1418</div>
1419
1420<!-- ======================================================================= -->
1421<div class="doc_subsubsection">
1422 <a name="ccxx_basic_long_long">long long</a>
1423</div>
1424
1425<div class="doc_text">
1426
1427<pre>
1428%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1429 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1430 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1431 sbyte* getelementptr ([14 x sbyte]* %str1, int 0, int 0),
1432 { }* null,
1433 int 0,
1434 uint 64,
1435 uint 64,
1436 uint 0,
1437 uint 5 }, section "llvm.metadata"
1438%str1 = internal constant [14 x sbyte] c"long long int\00", section "llvm.metadata"
1439</pre>
1440
1441</div>
1442
1443<!-- ======================================================================= -->
1444<div class="doc_subsubsection">
1445 <a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
1446</div>
1447
1448<div class="doc_text">
1449
1450<pre>
1451%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1452 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1453 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1454 sbyte* getelementptr ([23 x sbyte]* %str1, int 0, int 0),
1455 { }* null,
1456 int 0,
1457 uint 64,
1458 uint 64,
1459 uint 0,
1460 uint 7 }, section "llvm.metadata"
1461%str1 = internal constant [23 x sbyte] c"long long unsigned int\00", section "llvm.metadata"
1462</pre>
1463
1464</div>
1465
1466<!-- ======================================================================= -->
1467<div class="doc_subsubsection">
1468 <a name="ccxx_basic_float">float</a>
1469</div>
1470
1471<div class="doc_text">
1472
1473<pre>
1474%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1475 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1476 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1477 sbyte* getelementptr ([6 x sbyte]* %str1, int 0, int 0),
1478 { }* null,
1479 int 0,
1480 uint 32,
1481 uint 32,
1482 uint 0,
1483 uint 4 }, section "llvm.metadata"
1484%str1 = internal constant [6 x sbyte] c"float\00", section "llvm.metadata"
1485</pre>
1486
1487</div>
1488
1489<!-- ======================================================================= -->
1490<div class="doc_subsubsection">
1491 <a name="ccxx_basic_double">double</a>
1492</div>
1493
1494<div class="doc_text">
1495
1496<pre>
1497%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1498 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1499 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1500 sbyte* getelementptr ([7 x sbyte]* %str1, int 0, int 0),
1501 { }* null,
1502 int 0,
1503 uint 64,
1504 uint 64,
1505 uint 0,
1506 uint 4 }, section "llvm.metadata"
1507%str1 = internal constant [7 x sbyte] c"double\00", section "llvm.metadata"
1508</pre>
1509
1510</div>
1511
1512<!-- ======================================================================= -->
1513<div class="doc_subsection">
1514 <a name="ccxx_derived_types">C/C++ derived types</a>
1515</div>
1516
1517<div class="doc_text">
1518
1519<p>Given the following as an example of C/C++ derived type;</p>
1520
1521<pre>
1522typedef const int *IntPtr;
1523</pre>
1524
1525<p>a C/C++ front-end would generate the following descriptors;</p>
1526
1527<pre>
1528;;
1529;; Define the typedef "IntPtr".
1530;;
1531%<a href="#format_derived_type">llvm.dbg.derivedtype1</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1532 uint add(uint 22, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1533 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1534 sbyte* getelementptr ([7 x sbyte]* %str1, int 0, int 0),
1535 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1536 int 1,
1537 uint 0,
1538 uint 0,
1539 uint 0,
1540 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype2</a> to { }*) }, section "llvm.metadata"
1541%str1 = internal constant [7 x sbyte] c"IntPtr\00", section "llvm.metadata"
1542
1543;;
1544;; Define the pointer type.
1545;;
1546%<a href="#format_derived_type">llvm.dbg.derivedtype2</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1547 uint add(uint 15, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1548 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
Jim Laskey4d9b10b2006-03-14 18:50:50 +0000[diff] [blame]1549 sbyte* null,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1550 { }* null,
1551 int 0,
1552 uint 32,
1553 uint 32,
1554 uint 0,
1555 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype3</a> to { }*) }, section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1556
1557;;
1558;; Define the const type.
1559;;
1560%<a href="#format_derived_type">llvm.dbg.derivedtype3</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1561 uint add(uint 38, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1562 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
Jim Laskey4d9b10b2006-03-14 18:50:50 +0000[diff] [blame]1563 sbyte* null,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1564 { }* null,
1565 int 0,
1566 uint 0,
1567 uint 0,
1568 uint 0,
1569 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype1</a> to { }*) }, section "llvm.metadata"
1570
1571;;
1572;; Define the int type.
1573;;
1574%<a href="#format_basic_type">llvm.dbg.basictype1</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1575 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1576 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
Jim Laskey4d9b10b2006-03-14 18:50:50 +0000[diff] [blame]1577 sbyte* getelementptr ([4 x sbyte]* %str2, int 0, int 0),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1578 { }* null,
1579 int 0,
1580 uint 32,
1581 uint 32,
1582 uint 0,
1583 uint 5 }, section "llvm.metadata"
Jim Laskey4d9b10b2006-03-14 18:50:50 +0000[diff] [blame]1584%str2 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1585</pre>
1586
1587</div>
1588
1589<!-- ======================================================================= -->
1590<div class="doc_subsection">
1591 <a name="ccxx_composite_types">C/C++ struct/union types</a>
1592</div>
1593
1594<div class="doc_text">
1595
1596<p>Given the following as an example of C/C++ struct type;</p>
1597
1598<pre>
1599struct Color {
1600 unsigned Red;
1601 unsigned Green;
1602 unsigned Blue;
1603};
1604</pre>
1605
1606<p>a C/C++ front-end would generate the following descriptors;</p>
1607
1608<pre>
1609;;
1610;; Define basic type for unsigned int.
1611;;
1612%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1613 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1614 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1615 sbyte* getelementptr ([13 x sbyte]* %str1, int 0, int 0),
1616 { }* null,
1617 int 0,
1618 uint 32,
1619 uint 32,
1620 uint 0,
1621 uint 7 }, section "llvm.metadata"
1622%str1 = internal constant [13 x sbyte] c"unsigned int\00", section "llvm.metadata"
1623
1624;;
1625;; Define composite type for struct Color.
1626;;
1627%<a href="#format_composite_type">llvm.dbg.compositetype</a> = internal constant %<a href="#format_composite_type">llvm.dbg.compositetype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1628 uint add(uint 19, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1629 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1630 sbyte* getelementptr ([6 x sbyte]* %str2, int 0, int 0),
1631 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1632 int 1,
1633 uint 96,
1634 uint 32,
1635 uint 0,
Jim Laskeyf8a01a92006-06-15 20:51:43 +0000[diff] [blame]1636 { }* null,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1637 { }* cast ([3 x { }*]* %llvm.dbg.array to { }*) }, section "llvm.metadata"
1638%str2 = internal constant [6 x sbyte] c"Color\00", section "llvm.metadata"
1639
1640;;
1641;; Define the Red field.
1642;;
1643%<a href="#format_derived_type">llvm.dbg.derivedtype1</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1644 uint add(uint 13, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1645 { }* null,
1646 sbyte* getelementptr ([4 x sbyte]* %str3, int 0, int 0),
1647 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1648 int 2,
1649 uint 32,
1650 uint 32,
1651 uint 0,
1652 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
1653%str3 = internal constant [4 x sbyte] c"Red\00", section "llvm.metadata"
1654
1655;;
1656;; Define the Green field.
1657;;
1658%<a href="#format_derived_type">llvm.dbg.derivedtype2</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1659 uint add(uint 13, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1660 { }* null,
1661 sbyte* getelementptr ([6 x sbyte]* %str4, int 0, int 0),
1662 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1663 int 3,
1664 uint 32,
1665 uint 32,
1666 uint 32,
1667 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
1668%str4 = internal constant [6 x sbyte] c"Green\00", section "llvm.metadata"
1669
1670;;
1671;; Define the Blue field.
1672;;
1673%<a href="#format_derived_type">llvm.dbg.derivedtype3</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1674 uint add(uint 13, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1675 { }* null,
1676 sbyte* getelementptr ([5 x sbyte]* %str5, int 0, int 0),
1677 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1678 int 4,
1679 uint 32,
1680 uint 32,
1681 uint 64,
1682 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
1683%str5 = internal constant [5 x sbyte] c"Blue\00", section "llvm.metadata"
1684
1685;;
1686;; Define the array of fields used by the composite type Color.
1687;;
1688%llvm.dbg.array = internal constant [3 x { }*] [
1689 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype1</a> to { }*),
1690 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype2</a> to { }*),
1691 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype3</a> to { }*) ], section "llvm.metadata"
1692</pre>
1693
1694</div>
1695
1696<!-- ======================================================================= -->
1697<div class="doc_subsection">
1698 <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
1699</div>
1700
1701<div class="doc_text">
1702
1703<p>Given the following as an example of C/C++ enumeration type;</p>
1704
1705<pre>
1706enum Trees {
1707 Spruce = 100,
1708 Oak = 200,
1709 Maple = 300
1710};
1711</pre>
1712
1713<p>a C/C++ front-end would generate the following descriptors;</p>
1714
1715<pre>
1716;;
1717;; Define composite type for enum Trees
1718;;
1719%<a href="#format_composite_type">llvm.dbg.compositetype</a> = internal constant %<a href="#format_composite_type">llvm.dbg.compositetype.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1720 uint add(uint 4, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1721 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1722 sbyte* getelementptr ([6 x sbyte]* %str1, int 0, int 0),
1723 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1724 int 1,
1725 uint 32,
1726 uint 32,
1727 uint 0,
1728 { }* null,
1729 { }* cast ([3 x { }*]* %llvm.dbg.array to { }*) }, section "llvm.metadata"
1730%str1 = internal constant [6 x sbyte] c"Trees\00", section "llvm.metadata"
1731
1732;;
1733;; Define Spruce enumerator.
1734;;
1735%<a href="#format_enumeration">llvm.dbg.enumerator1</a> = internal constant %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1736 uint add(uint 40, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1737 sbyte* getelementptr ([7 x sbyte]* %str2, int 0, int 0),
1738 int 100 }, section "llvm.metadata"
1739%str2 = internal constant [7 x sbyte] c"Spruce\00", section "llvm.metadata"
1740
1741;;
1742;; Define Oak enumerator.
1743;;
1744%<a href="#format_enumeration">llvm.dbg.enumerator2</a> = internal constant %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1745 uint add(uint 40, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1746 sbyte* getelementptr ([4 x sbyte]* %str3, int 0, int 0),
1747 int 200 }, section "llvm.metadata"
1748%str3 = internal constant [4 x sbyte] c"Oak\00", section "llvm.metadata"
1749
1750;;
1751;; Define Maple enumerator.
1752;;
1753%<a href="#format_enumeration">llvm.dbg.enumerator3</a> = internal constant %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]1754 uint add(uint 40, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1755 sbyte* getelementptr ([6 x sbyte]* %str4, int 0, int 0),
1756 int 300 }, section "llvm.metadata"
1757%str4 = internal constant [6 x sbyte] c"Maple\00", section "llvm.metadata"
1758
1759;;
1760;; Define the array of enumerators used by composite type Trees.
1761;;
1762%llvm.dbg.array = internal constant [3 x { }*] [
1763 { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator1</a> to { }*),
1764 { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator2</a> to { }*),
1765 { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator3</a> to { }*) ], section "llvm.metadata"
1766</pre>
1767
1768</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1769
1770<!-- *********************************************************************** -->
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1771
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1772<hr>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1773<address>
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1778
1779 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]1780 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1781 Last modified: $Date$
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1782</address>
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