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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>
69 and <a href="mailto:jlaskey@apple.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
284<p>The fields of debug descriptors used internally by LLVM (MachineDebugInfo)
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 Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]392 { }*, ;; Reference to compile unit where defined
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]393 uint, ;; Line number where defined
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]394 { }*, ;; Reference to type descriptor
395 bool, ;; True if the global is local to compile unit (static)
396 bool, ;; True if the global is defined in the compile unit (not extern)
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]397 { }* ;; Reference to the global variable
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]398 }
399</pre>
400
401<p>These descriptors provide debug information about globals variables. The
402provide details such as name, type and where the variable is defined.</p>
403
404</div>
405
406<!-- ======================================================================= -->
407<div class="doc_subsubsection">
408 <a name="format_subprograms">Subprogram descriptors</a>
409</div>
410
411<div class="doc_text">
412
413<pre>
414 %<a href="#format_subprograms">llvm.dbg.subprogram.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]415 uint, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subprogram)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]416 { }*, ;; 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]417 { }*, ;; Reference to context descriptor
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]418 sbyte*, ;; Name
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]419 { }*, ;; Reference to compile unit where defined
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]420 uint, ;; Line number where defined
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]421 { }*, ;; Reference to type descriptor
422 bool, ;; True if the global is local to compile unit (static)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]423 bool ;; True if the global is defined in the compile unit (not extern)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]424 }
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]425</pre>
426
427<p>These descriptors provide debug information about functions, methods and
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]428subprograms. They provide details such as name, return types and the source
429location where the subprogram is defined.</p>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]430
431</div>
432<!-- ======================================================================= -->
433<div class="doc_subsubsection">
434 <a name="format_blocks">Block descriptors</a>
435</div>
436
437<div class="doc_text">
438
439<pre>
440 %<a href="#format_blocks">llvm.dbg.block</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]441 uint, ;; Tag = 13 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]442 { }* ;; Reference to context descriptor
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]443 }
444</pre>
445
446<p>These descriptors provide debug information about nested blocks within a
447subprogram. The array of member descriptors is used to define local variables
448and deeper nested blocks.</p>
449
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]450</div>
451
452<!-- ======================================================================= -->
453<div class="doc_subsubsection">
454 <a name="format_basic_type">Basic type descriptors</a>
455</div>
456
457<div class="doc_text">
458
459<pre>
460 %<a href="#format_basic_type">llvm.dbg.basictype.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]461 uint, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_base_type)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]462 { }*, ;; Reference to context (typically a compile unit)
463 sbyte*, ;; Name (may be "" for anonymous types)
464 { }*, ;; Reference to compile unit where defined (may be NULL)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]465 uint, ;; Line number where defined (may be 0)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]466 uint, ;; Size in bits
467 uint, ;; Alignment in bits
468 uint, ;; Offset in bits
469 uint ;; Dwarf type encoding
470 }
471</pre>
472
473<p>These descriptors define primitive types used in the code. Example int, bool
474and float. The context provides the scope of the type, which is usually the top
475level. Since basic types are not usually user defined the compile unit and line
476number can be left as NULL and 0. The size, alignment and offset are expressed
477in bits and can be 64 bit values. The alignment is used to round the offset
478when embedded in a <a href="#format_composite_type">composite type</a>
479(example to keep float doubles on 64 bit boundaries.) The offset is the bit
480offset if embedded in a <a href="#format_composite_type">composite
481type</a>.</p>
482
483<p>The type encoding provides the details of the type. The values are typically
484one of the following;</p>
485
486<pre>
487 DW_ATE_address = 1
488 DW_ATE_boolean = 2
489 DW_ATE_float = 4
490 DW_ATE_signed = 5
491 DW_ATE_signed_char = 6
492 DW_ATE_unsigned = 7
493 DW_ATE_unsigned_char = 8
494</pre>
495
496</div>
497
498<!-- ======================================================================= -->
499<div class="doc_subsubsection">
500 <a name="format_derived_type">Derived type descriptors</a>
501</div>
502
503<div class="doc_text">
504
505<pre>
506 %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> = type {
507 uint, ;; Tag (see below)
508 { }*, ;; Reference to context
509 sbyte*, ;; Name (may be "" for anonymous types)
510 { }*, ;; Reference to compile unit where defined (may be NULL)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]511 uint, ;; Line number where defined (may be 0)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]512 uint, ;; Size in bits
513 uint, ;; Alignment in bits
514 uint, ;; Offset in bits
515 { }* ;; Reference to type derived from
516 }
517</pre>
518
519<p>These descriptors are used to define types derived from other types. The
520value of the tag varies depending on the meaning. The following are possible
521tag values;</p>
522
523<pre>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]524 DW_TAG_formal_parameter = 5
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]525 DW_TAG_member = 13
526 DW_TAG_pointer_type = 15
527 DW_TAG_reference_type = 16
528 DW_TAG_typedef = 22
529 DW_TAG_const_type = 38
530 DW_TAG_volatile_type = 53
531 DW_TAG_restrict_type = 55
532</pre>
533
534<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]535href="#format_composite_type">composite type</a> or <a
536href="#format_subprograms">subprogram</a>. The type of the member is the <a
537href="#format_derived_type">derived type</a>. <tt>DW_TAG_formal_parameter</tt>
538is used to define a member which is a formal argument of a subprogram.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]539
540<p><tt>DW_TAG_typedef</tt> is used to
541provide a name for the derived type.</p>
542
543<p><tt>DW_TAG_pointer_type</tt>,
544<tt>DW_TAG_reference_type</tt>, <tt>DW_TAG_const_type</tt>,
545<tt>DW_TAG_volatile_type</tt> and <tt>DW_TAG_restrict_type</tt> are used to
546qualify the <a href="#format_derived_type">derived type</a>. </p>
547
548<p><a href="#format_derived_type">Derived type</a> location can be determined
549from the compile unit and line number. The size, alignment and offset are
550expressed in bits and can be 64 bit values. The alignment is used to round the
551offset when embedded in a <a href="#format_composite_type">composite type</a>
552(example to keep float doubles on 64 bit boundaries.) The offset is the bit
553offset if embedded in a <a href="#format_composite_type">composite
554type</a>.</p>
555
556<p>Note that the <tt>void *</tt> type is expressed as a
557<tt>llvm.dbg.derivedtype.type</tt> with tag of <tt>DW_TAG_pointer_type</tt> and
558NULL derived type.</p>
559
560</div>
561
562<!-- ======================================================================= -->
563<div class="doc_subsubsection">
564 <a name="format_composite_type">Composite type descriptors</a>
565</div>
566
567<div class="doc_text">
568
569<pre>
570 %<a href="#format_composite_type">llvm.dbg.compositetype.type</a> = type {
571 uint, ;; Tag (see below)
572 { }*, ;; Reference to context
573 sbyte*, ;; Name (may be "" for anonymous types)
574 { }*, ;; Reference to compile unit where defined (may be NULL)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]575 uint, ;; Line number where defined (may be 0)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]576 uint, ;; Size in bits
577 uint, ;; Alignment in bits
578 uint, ;; Offset in bits
579 { }* ;; Reference to array of member descriptors
580 }
581</pre>
582
583<p>These descriptors are used to define types that are composed of 0 or more
584elements. The value of the tag varies depending on the meaning. The following
585are possible tag values;</p>
586
587<pre>
588 DW_TAG_array_type = 1
589 DW_TAG_enumeration_type = 4
590 DW_TAG_structure_type = 19
591 DW_TAG_union_type = 23
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]592 DW_TAG_vector_type = 259
Jim Laskey094ee722006-06-20 21:13:20 +0000[diff] [blame]593 DW_TAG_subroutine_type = 46
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]594</pre>
595
Jim Laskeyf8a01a92006-06-15 20:51:43 +0000[diff] [blame]596<p>The vector flag indicates that an array type is a native packed vector.</p>
597
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]598<p>The members of array types (tag = <tt>DW_TAG_array_type</tt>) or vector types
599(tag = <tt>DW_TAG_vector_type</tt>) are <a href="#format_subrange">subrange
600descriptors</a>, each representing the range of subscripts at that level of
601indexing.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]602
603<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
604<a href="#format_enumeration">enumerator descriptors</a>, each representing the
605definition of enumeration value
606for the set.</p>
607
608<p>The members of structure (tag = <tt>DW_TAG_structure_type</tt>) or union (tag
609= <tt>DW_TAG_union_type</tt>) types are any one of the <a
610href="#format_basic_type">basic</a>, <a href="#format_derived_type">derived</a>
611or <a href="#format_composite_type">composite</a> type descriptors, each
612representing a field member of the structure or union.</p>
613
Jim Laskeyb329fe12006-06-21 11:08:10 +0000[diff] [blame^]614<p>The first member of subroutine (tag = <tt>DW_TAG_subroutine_type</tt>)
615type elements is the return type for the subroutine. The remaining
Jim Laskey094ee722006-06-20 21:13:20 +0000[diff] [blame]616elements are the formal arguments to the subroutine.</p>
617
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]618<p><a href="#format_composite_type">Composite type</a> location can be
619determined from the compile unit and line number. The size, alignment and
620offset are expressed in bits and can be 64 bit values. The alignment is used to
621round the offset when embedded in a <a href="#format_composite_type">composite
622type</a> (as an example, to keep float doubles on 64 bit boundaries.) The offset
623is the bit offset if embedded in a <a href="#format_composite_type">composite
624type</a>.</p>
625
626</div>
627
628<!-- ======================================================================= -->
629<div class="doc_subsubsection">
630 <a name="format_subrange">Subrange descriptors</a>
631</div>
632
633<div class="doc_text">
634
635<pre>
636 %<a href="#format_subrange">llvm.dbg.subrange.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]637 uint, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]638 uint, ;; Low value
639 uint ;; High value
640 }
641</pre>
642
643<p>These descriptors are used to define ranges of array subscripts for an array
644<a href="#format_composite_type">composite type</a>. The low value defines the
645lower bounds typically zero for C/C++. The high value is the upper bounds.
646Values are 64 bit. High - low + 1 is the size of the array. If
647low == high the array will be unbounded.</p>
648
649</div>
650
651<!-- ======================================================================= -->
652<div class="doc_subsubsection">
653 <a name="format_enumeration">Enumerator descriptors</a>
654</div>
655
656<div class="doc_text">
657
658<pre>
659 %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]660 uint, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_enumerator)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]661 sbyte*, ;; Name
662 uint ;; Value
663 }
664</pre>
665
666<p>These descriptors are used to define members of an enumeration <a
667href="#format_composite_type">composite type</a>, it associates the name to the
668value.</p>
669
670</div>
671
672<!-- ======================================================================= -->
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]673<div class="doc_subsubsection">
674 <a name="format_variables">Local variables</a>
675</div>
676
677<div class="doc_text">
678<pre>
679 %<a href="#format_variables">llvm.dbg.variable.type</a> = type {
680 uint, ;; Tag (see below)
681 { }*, ;; Context
682 sbyte*, ;; Name
683 { }*, ;; Reference to compile unit where defined
684 uint, ;; Line number where defined
685 { }* ;; Type descriptor
686 }
687</pre>
688
689<p>These descriptors are used to define variables local to a sub program. The
690value of the tag depends on the usage of the variable;</p>
691
692<pre>
693 DW_TAG_auto_variable = 256
694 DW_TAG_arg_variable = 257
695 DW_TAG_return_variable = 258
696</pre>
697
698<p>An auto variable is any variable declared in the body of the function. An
699argument variable is any variable that appears as a formal argument to the
700function. A return variable is used to track the result of a function and has
701no source correspondent.</p>
702
Jim Laskey2d395d92006-03-24 09:20:27 +0000[diff] [blame]703<p>The context is either the subprogram or block where the variable is defined.
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]704Name the source variable name. Compile unit and line indicate where the
705variable was defined. Type descriptor defines the declared type of the
706variable.</p>
707
708</div>
709
710<!-- ======================================================================= -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]711<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]712 <a name="format_common_intrinsics">Debugger intrinsic functions</a>
713</div>
714
715<div class="doc_text">
716
717<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
718provide debug information at various points in generated code.</p>
719
720</div>
721
722<!-- ======================================================================= -->
723<div class="doc_subsubsection">
724 <a name="format_common_stoppoint">llvm.dbg.stoppoint</a>
725</div>
726
727<div class="doc_text">
728<pre>
Jim Laskey108a6382006-03-23 17:58:46 +0000[diff] [blame]729 void %<a href="#format_common_stoppoint">llvm.dbg.stoppoint</a>( uint, uint, { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]730</pre>
731
732<p>This intrinsic is used to provide correspondence between the source file and
733the generated code. The first argument is the line number (base 1), second
734argument si the column number (0 if unknown) and the third argument the source
Jim Laskey108a6382006-03-23 17:58:46 +0000[diff] [blame]735<tt>%<a href="#format_compile_units">llvm.dbg.compile_unit</a>*</tt> cast to a
736<tt>{ }*</tt>. Code following a call to this intrinsic will have been defined
737in close proximity of the line, column and file. This information holds until
738the next call to <tt>%<a
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]739href="#format_common_stoppoint">lvm.dbg.stoppoint</a></tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]740
741</div>
742
743<!-- ======================================================================= -->
744<div class="doc_subsubsection">
745 <a name="format_common_func_start">llvm.dbg.func.start</a>
746</div>
747
748<div class="doc_text">
749<pre>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]750 void %<a href="#format_common_func_start">llvm.dbg.func.start</a>( { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]751</pre>
752
753<p>This intrinsic is used to link the debug information in <tt>%<a
754href="#format_subprograms">llvm.dbg.subprogram</a></tt> to the function. It also
755defines the beginning of the function's declarative region (scope.) The
756intrinsic should be called early in the function after the all the alloca
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]757instructions. It should be paired off with a closing <tt>%<a
758href="#format_common_region_end">llvm.dbg.region.end</a></tt>. The function's
759single argument is the <tt>%<a
760href="#format_subprograms">llvm.dbg.subprogram.type</a></tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]761
762</div>
763
764<!-- ======================================================================= -->
765<div class="doc_subsubsection">
766 <a name="format_common_region_start">llvm.dbg.region.start</a>
767</div>
768
769<div class="doc_text">
770<pre>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]771 void %<a href="#format_common_region_start">llvm.dbg.region.start</a>( { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]772</pre>
773
774<p>This intrinsic is used to define the beginning of a declarative scope (ex.
775block) for local language elements. It should be paired off with a closing
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]776<tt>%<a href="#format_common_region_end">llvm.dbg.region.end</a></tt>. The
777function's single argument is the <tt>%<a
778href="#format_blocks">llvm.dbg.block</a></tt> which is starting.</p>
779
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_end">llvm.dbg.region.end</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_end">llvm.dbg.region.end</a>( { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]791</pre>
792
793<p>This intrinsic is used to define the end of a declarative scope (ex. block)
794for local language elements. It should be paired off with an opening <tt>%<a
795href="#format_common_region_start">llvm.dbg.region.start</a></tt> or <tt>%<a
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]796href="#format_common_func_start">llvm.dbg.func.start</a></tt>. The function's
797single argument is either the <tt>%<a
798href="#format_blocks">llvm.dbg.block</a></tt> or the <tt>%<a
799href="#format_subprograms">llvm.dbg.subprogram.type</a></tt> which is
800ending.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]801
802</div>
803
804<!-- ======================================================================= -->
805<div class="doc_subsubsection">
806 <a name="format_common_declare">llvm.dbg.declare</a>
807</div>
808
809<div class="doc_text">
810<pre>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]811 void %<a href="#format_common_declare">llvm.dbg.declare</a>( { } *, { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]812</pre>
813
Jim Laskey2d395d92006-03-24 09:20:27 +0000[diff] [blame]814<p>This intrinsic provides information about a local element (ex. variable.) The
815first argument is the alloca for the variable, cast to a <tt>{ }*</tt>. The
816second argument is the <tt>%<a
817href="#format_variables">llvm.dbg.variable</a></tt> containing the description
818of the variable, also cast to a <tt>{ }*</tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]819
820</div>
821
822<!-- ======================================================================= -->
823<div class="doc_subsection">
824 <a name="format_common_stoppoints">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]825 Representing stopping points in the source program
826 </a>
827</div>
828
829<div class="doc_text">
830
831<p>LLVM debugger "stop points" are a key part of the debugging representation
832that allows the LLVM to maintain simple semantics for <a
833href="#debugopt">debugging optimized code</a>. The basic idea is that the
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]834front-end inserts calls to the <a
835href="#format_common_stoppoint">%<tt>llvm.dbg.stoppoint</tt></a> intrinsic
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]836function at every point in the program where a debugger should be able to
837inspect the program (these correspond to places a debugger stops when you
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]838"<tt>step</tt>" through it). The front-end can choose to place these as
839fine-grained as it would like (for example, before every subexpression
840evaluated), but it is recommended to only put them after every source statement
841that includes executable code.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]842
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]843<p>Using calls to this intrinsic function to demark legal points for the
844debugger to inspect the program automatically disables any optimizations that
845could potentially confuse debugging information. To non-debug-information-aware
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]846transformations, these calls simply look like calls to an external function,
847which they must assume to do anything (including reading or writing to any part
848of reachable memory). On the other hand, it does not impact many optimizations,
849such as code motion of non-trapping instructions, nor does it impact
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]850optimization of subexpressions, code duplication transformations, or basic-block
851reordering transformations.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]852
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]853</div>
854
855
856<!-- ======================================================================= -->
857<div class="doc_subsection">
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]858 <a name="format_common_lifetime">Object lifetimes and scoping</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]859</div>
860
861<div class="doc_text">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]862<p>In many languages, the local variables in functions can have their lifetime
863or 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]864example, variables are only live (readable and writable) within the source block
865that they are defined in. In functional languages, values are only readable
866after they have been defined. Though this is a very obvious concept, it is also
867non-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]868and does not want to be tied to a language's scoping rules.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]869
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]870<p>In order to handle this, the LLVM debug format uses the notion of "regions"
871of a function, delineated by calls to intrinsic functions. These intrinsic
872functions define new regions of the program and indicate when the region
873lifetime expires. Consider the following C fragment, for example:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]874
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]875<pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]8761. void foo() {
8772. int X = ...;
8783. int Y = ...;
8794. {
8805. int Z = ...;
8816. ...
8827. }
8838. ...
8849. }
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]885</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]886
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]887<p>Compiled to LLVM, this function would be represented like this:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]888
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]889<pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]890void %foo() {
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]891entry:
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]892 %X = alloca int
893 %Y = alloca int
894 %Z = alloca int
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]895
896 ...
897
898 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 )
899
900 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 )
901
902 call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %X, ...)
903 call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %Y, ...)
904
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]905 <i>;; Evaluate expression on line 2, assigning to X.</i>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]906
907 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 )
908
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]909 <i>;; Evaluate expression on line 3, assigning to Y.</i>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]910
911 call void %<a href="#format_common_stoppoint">llvm.region.start</a>()
912 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 )
913 call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %X, ...)
914
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]915 <i>;; Evaluate expression on line 5, assigning to Z.</i>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]916
917 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 )
918 call void %<a href="#format_common_region_end">llvm.region.end</a>()
919
920 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 )
921
922 call void %<a href="#format_common_region_end">llvm.region.end</a>()
923
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]924 ret void
925}
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]926</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]927
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]928<p>This example illustrates a few important details about the LLVM debugging
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]929information. In particular, it shows how the various intrinsics are applied
930together to allow a debugger to analyze the relationship between statements,
931variable definitions, and the code used to implement the function.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]932
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]933<p>The first intrinsic <tt>%<a
934href="#format_common_func_start">llvm.dbg.func.start</a></tt> provides
935a link with the <a href="#format_subprograms">subprogram descriptor</a>
936containing the details of this function. This call also defines the beginning
937of the function region, bounded by the <tt>%<a
938href="#format_common_region_end">llvm.region.end</a></tt> at the end of
939the function. This region is used to bracket the lifetime of variables declared
940within. For a function, this outer region defines a new stack frame whose
941lifetime ends when the region is ended.</p>
942
943<p>It is possible to define inner regions for short term variables by using the
944%<a href="#format_common_stoppoint"><tt>llvm.region.start</tt></a> and <a
945href="#format_common_region_end"><tt>%llvm.region.end</tt></a> to bound a
946region. The inner region in this example would be for the block containing the
947declaration of Z.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]948
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]949<p>Using regions to represent the boundaries of source-level functions allow
950LLVM interprocedural optimizations to arbitrarily modify LLVM functions without
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]951having to worry about breaking mapping information between the LLVM code and the
952and source-level program. In particular, the inliner requires no modification
953to support inlining with debugging information: there is no explicit correlation
954drawn between LLVM functions and their source-level counterparts (note however,
955that if the inliner inlines all instances of a non-strong-linkage function into
956its caller that it will not be possible for the user to manually invoke the
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]957inlined function from a debugger).</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]958
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]959<p>Once the function has been defined, the <a
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]960href="#format_common_stoppoint"><tt>stopping point</tt></a> corresponding to
961line #2 (column #2) of the function is encountered. At this point in the
962function, <b>no</b> local variables are live. As lines 2 and 3 of the example
963are executed, their variable definitions are introduced into the program using
964%<a href="#format_common_declare"><tt>llvm.dbg.declare</tt></a>, without the
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]965need to specify a new region. These variables do not require new regions to be
966introduced because they go out of scope at the same point in the program: line
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]9679.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]968
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]969<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]970on line 7. For this reason, it is defined within the inner region, which kills
971the availability of <tt>Z</tt> before the code for line 8 is executed. In this
972way, regions can support arbitrary source-language scoping rules, as long as
973they can only be nested (ie, one scope cannot partially overlap with a part of
974another scope).</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]975
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]976<p>It is worth noting that this scoping mechanism is used to control scoping of
977all declarations, not just variable declarations. For example, the scope of a
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]978C++ using declaration is controlled with this couldchange how name lookup is
979performed.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]980
981</div>
982
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]983
984
985<!-- *********************************************************************** -->
986<div class="doc_section">
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]987 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]988</div>
Misha Brukman94218a72004-12-09 20:27:37 +0000[diff] [blame]989<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]990
991<div class="doc_text">
992
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]993<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]994that is effectively identical to <a
995href="http://www.eagercon.com/dwarf/dwarf3std.htm">Dwarf 3.0</a> in terms of
996information content. This allows code generators to trivially support native
997debuggers by generating standard dwarf information, and contains enough
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]998information for non-dwarf targets to translate it as needed.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]999
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1000<p>This section describes the forms used to represent C and C++ programs. Other
1001languages could pattern themselves after this (which itself is tuned to
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1002representing programs in the same way that Dwarf 3 does), or they could choose
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1003to provide completely different forms if they don't fit into the Dwarf model.
1004As support for debugging information gets added to the various LLVM
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1005source-language front-ends, the information used should be documented here.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1006
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1007<p>The following sections provide examples of various C/C++ constructs and the
1008debug information that would best describe those constructs.</p>
1009
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1010</div>
1011
1012<!-- ======================================================================= -->
1013<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1014 <a name="ccxx_compile_units">C/C++ source file information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1015</div>
1016
1017<div class="doc_text">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1018
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1019<p>Given the source files "MySource.cpp" and "MyHeader.h" located in the
1020directory "/Users/mine/sources", the following code;</p>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1021
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1022<pre>
1023#include "MyHeader.h"
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1024
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1025int main(int argc, char *argv[]) {
1026 return 0;
1027}
1028</pre>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1029
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1030<p>a C/C++ front-end would generate the following descriptors;</p>
1031
1032<pre>
1033...
1034;;
1035;; Define types used. In this case we need one for compile unit anchors and one
1036;; for compile units.
1037;;
1038%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
1039%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = type { uint, { }*, uint, uint, sbyte*, sbyte*, sbyte* }
1040...
1041;;
1042;; Define the anchor for compile units. Note that the second field of the
1043;; anchor is 17, which is the same as the tag for compile units
1044;; (17 = DW_TAG_compile_unit.)
1045;;
1046%<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"
1047
1048;;
1049;; Define the compile unit for the source file "/Users/mine/sources/MySource.cpp".
1050;;
1051%<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]1052 uint add(uint 17, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1053 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_units</a> to { }*),
1054 uint 1,
1055 uint 1,
1056 sbyte* getelementptr ([13 x sbyte]* %str1, int 0, int 0),
1057 sbyte* getelementptr ([21 x sbyte]* %str2, int 0, int 0),
1058 sbyte* getelementptr ([33 x sbyte]* %str3, int 0, int 0) }, section "llvm.metadata"
1059
1060;;
1061;; Define the compile unit for the header file "/Users/mine/sources/MyHeader.h".
1062;;
1063%<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]1064 uint add(uint 17, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1065 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_units</a> to { }*),
1066 uint 1,
1067 uint 1,
1068 sbyte* getelementptr ([11 x sbyte]* %str4, int 0, int 0),
1069 sbyte* getelementptr ([21 x sbyte]* %str2, int 0, int 0),
1070 sbyte* getelementptr ([33 x sbyte]* %str3, int 0, int 0) }, section "llvm.metadata"
1071
1072;;
1073;; Define each of the strings used in the compile units.
1074;;
1075%str1 = internal constant [13 x sbyte] c"MySource.cpp\00", section "llvm.metadata";
1076%str2 = internal constant [21 x sbyte] c"/Users/mine/sources/\00", section "llvm.metadata";
1077%str3 = internal constant [33 x sbyte] c"4.0.1 LLVM (LLVM research group)\00", section "llvm.metadata";
1078%str4 = internal constant [11 x sbyte] c"MyHeader.h\00", section "llvm.metadata";
1079...
1080</pre>
1081
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1082</div>
1083
1084<!-- ======================================================================= -->
1085<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1086 <a name="ccxx_global_variable">C/C++ global variable information</a>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1087</div>
1088
1089<div class="doc_text">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1090
1091<p>Given an integer global variable declared as follows;</p>
1092
1093<pre>
1094int MyGlobal = 100;
1095</pre>
1096
1097<p>a C/C++ front-end would generate the following descriptors;</p>
1098
1099<pre>
1100;;
1101;; Define types used. One for global variable anchors, one for the global
1102;; variable descriptor, one for the global's basic type and one for the global's
1103;; compile unit.
1104;;
1105%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1106%<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]1107%<a href="#format_basic_type">llvm.dbg.basictype.type</a> = type { uint, { }*, sbyte*, { }*, int, uint, uint, uint, uint }
1108%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = ...
1109...
1110;;
1111;; Define the global itself.
1112;;
1113%MyGlobal = global int 100
1114...
1115;;
1116;; Define the anchor for global variables. Note that the second field of the
1117;; anchor is 52, which is the same as the tag for global variables
1118;; (52 = DW_TAG_variable.)
1119;;
1120%<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"
1121
1122;;
1123;; Define the global variable descriptor. Note the reference to the global
1124;; variable anchor and the global variable itself.
1125;;
1126%<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]1127 uint add(uint 52, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1128 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_global_variables">llvm.dbg.global_variables</a> to { }*),
1129 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1130 sbyte* getelementptr ([9 x sbyte]* %str1, int 0, int 0),
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1131 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1132 uint 1,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1133 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*),
1134 bool false,
1135 bool true,
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1136 { }* cast (int* %MyGlobal to { }*) }, section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1137
1138;;
1139;; Define the basic type of 32 bit signed integer. Note that since int is an
1140;; intrinsic type the source file is NULL and line 0.
1141;;
1142%<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]1143 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1144 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1145 sbyte* getelementptr ([4 x sbyte]* %str2, int 0, int 0),
1146 { }* null,
1147 int 0,
1148 uint 32,
1149 uint 32,
1150 uint 0,
1151 uint 5 }, section "llvm.metadata"
1152
1153;;
1154;; Define the names of the global variable and basic type.
1155;;
1156%str1 = internal constant [9 x sbyte] c"MyGlobal\00", section "llvm.metadata"
1157%str2 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
1158</pre>
1159
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1160</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1161
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1162<!-- ======================================================================= -->
1163<div class="doc_subsection">
1164 <a name="ccxx_subprogram">C/C++ function information</a>
1165</div>
1166
1167<div class="doc_text">
1168
1169<p>Given a function declared as follows;</p>
1170
1171<pre>
1172int main(int argc, char *argv[]) {
1173 return 0;
1174}
1175</pre>
1176
1177<p>a C/C++ front-end would generate the following descriptors;</p>
1178
1179<pre>
1180;;
1181;; Define types used. One for subprogram anchors, one for the subprogram
1182;; descriptor, one for the global's basic type and one for the subprogram's
1183;; compile unit.
1184;;
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]1185%<a href="#format_subprograms">llvm.dbg.subprogram.type</a> = type { uint, { }*, { }*, sbyte*, { }*, bool, bool }
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1186%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
1187%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = ...
1188
1189;;
1190;; Define the anchor for subprograms. Note that the second field of the
1191;; anchor is 46, which is the same as the tag for subprograms
1192;; (46 = DW_TAG_subprogram.)
1193;;
1194%<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"
1195
1196;;
1197;; Define the descriptor for the subprogram. TODO - more details.
1198;;
1199%<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]1200 uint add(uint 46, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1201 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_subprograms">llvm.dbg.subprograms</a> to { }*),
1202 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1203 sbyte* getelementptr ([5 x sbyte]* %str1, int 0, int 0),
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1204 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1205 uint 1,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1206 { }* null,
1207 bool false,
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]1208 bool true }, section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1209
1210;;
1211;; Define the name of the subprogram.
1212;;
1213%str1 = internal constant [5 x sbyte] c"main\00", section "llvm.metadata"
1214
1215;;
1216;; Define the subprogram itself.
1217;;
1218int %main(int %argc, sbyte** %argv) {
1219...
1220}
1221</pre>
1222
1223</div>
1224
1225<!-- ======================================================================= -->
1226<div class="doc_subsection">
1227 <a name="ccxx_basic_types">C/C++ basic types</a>
1228</div>
1229
1230<div class="doc_text">
1231
1232<p>The following are the basic type descriptors for C/C++ core types;</p>
1233
1234</div>
1235
1236<!-- ======================================================================= -->
1237<div class="doc_subsubsection">
1238 <a name="ccxx_basic_type_bool">bool</a>
1239</div>
1240
1241<div class="doc_text">
1242
1243<pre>
1244%<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]1245 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1246 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1247 sbyte* getelementptr ([5 x sbyte]* %str1, int 0, int 0),
1248 { }* null,
1249 int 0,
1250 uint 32,
1251 uint 32,
1252 uint 0,
1253 uint 2 }, section "llvm.metadata"
1254%str1 = internal constant [5 x sbyte] c"bool\00", section "llvm.metadata"
1255</pre>
1256
1257</div>
1258
1259<!-- ======================================================================= -->
1260<div class="doc_subsubsection">
1261 <a name="ccxx_basic_char">char</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 8,
1274 uint 8,
1275 uint 0,
1276 uint 6 }, section "llvm.metadata"
1277%str1 = internal constant [5 x sbyte] c"char\00", section "llvm.metadata"
1278</pre>
1279
1280</div>
1281
1282<!-- ======================================================================= -->
1283<div class="doc_subsubsection">
1284 <a name="ccxx_basic_unsigned_char">unsigned 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 ([14 x sbyte]* %str1, int 0, int 0),
1294 { }* null,
1295 int 0,
1296 uint 8,
1297 uint 8,
1298 uint 0,
1299 uint 8 }, section "llvm.metadata"
1300%str1 = internal constant [14 x sbyte] c"unsigned char\00", section "llvm.metadata"
1301</pre>
1302
1303</div>
1304
1305<!-- ======================================================================= -->
1306<div class="doc_subsubsection">
1307 <a name="ccxx_basic_short">short</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 ([10 x sbyte]* %str1, int 0, int 0),
1317 { }* null,
1318 int 0,
1319 uint 16,
1320 uint 16,
1321 uint 0,
1322 uint 5 }, section "llvm.metadata"
1323%str1 = internal constant [10 x sbyte] c"short int\00", section "llvm.metadata"
1324</pre>
1325
1326</div>
1327
1328<!-- ======================================================================= -->
1329<div class="doc_subsubsection">
1330 <a name="ccxx_basic_unsigned_short">unsigned 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 ([19 x sbyte]* %str1, int 0, int 0),
1340 { }* null,
1341 int 0,
1342 uint 16,
1343 uint 16,
1344 uint 0,
1345 uint 7 }, section "llvm.metadata"
1346%str1 = internal constant [19 x sbyte] c"short unsigned int\00", section "llvm.metadata"
1347</pre>
1348
1349</div>
1350
1351<!-- ======================================================================= -->
1352<div class="doc_subsubsection">
1353 <a name="ccxx_basic_int">int</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 ([4 x sbyte]* %str1, int 0, int 0),
1363 { }* null,
1364 int 0,
1365 uint 32,
1366 uint 32,
1367 uint 0,
1368 uint 5 }, section "llvm.metadata"
1369%str1 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
1370</pre>
1371
1372</div>
1373
1374<!-- ======================================================================= -->
1375<div class="doc_subsubsection">
1376 <a name="ccxx_basic_unsigned_int">unsigned 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 ([13 x sbyte]* %str1, int 0, int 0),
1386 { }* null,
1387 int 0,
1388 uint 32,
1389 uint 32,
1390 uint 0,
1391 uint 7 }, section "llvm.metadata"
1392%str1 = internal constant [13 x sbyte] c"unsigned int\00", section "llvm.metadata"
1393</pre>
1394
1395</div>
1396
1397<!-- ======================================================================= -->
1398<div class="doc_subsubsection">
1399 <a name="ccxx_basic_long_long">long long</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 ([14 x sbyte]* %str1, int 0, int 0),
1409 { }* null,
1410 int 0,
1411 uint 64,
1412 uint 64,
1413 uint 0,
1414 uint 5 }, section "llvm.metadata"
1415%str1 = internal constant [14 x sbyte] c"long long int\00", section "llvm.metadata"
1416</pre>
1417
1418</div>
1419
1420<!-- ======================================================================= -->
1421<div class="doc_subsubsection">
1422 <a name="ccxx_basic_unsigned_long_long">unsigned 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 ([23 x sbyte]* %str1, int 0, int 0),
1432 { }* null,
1433 int 0,
1434 uint 64,
1435 uint 64,
1436 uint 0,
1437 uint 7 }, section "llvm.metadata"
1438%str1 = internal constant [23 x sbyte] c"long long unsigned int\00", section "llvm.metadata"
1439</pre>
1440
1441</div>
1442
1443<!-- ======================================================================= -->
1444<div class="doc_subsubsection">
1445 <a name="ccxx_basic_float">float</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 ([6 x sbyte]* %str1, int 0, int 0),
1455 { }* null,
1456 int 0,
1457 uint 32,
1458 uint 32,
1459 uint 0,
1460 uint 4 }, section "llvm.metadata"
1461%str1 = internal constant [6 x sbyte] c"float\00", section "llvm.metadata"
1462</pre>
1463
1464</div>
1465
1466<!-- ======================================================================= -->
1467<div class="doc_subsubsection">
1468 <a name="ccxx_basic_double">double</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 ([7 x sbyte]* %str1, int 0, int 0),
1478 { }* null,
1479 int 0,
1480 uint 64,
1481 uint 64,
1482 uint 0,
1483 uint 4 }, section "llvm.metadata"
1484%str1 = internal constant [7 x sbyte] c"double\00", section "llvm.metadata"
1485</pre>
1486
1487</div>
1488
1489<!-- ======================================================================= -->
1490<div class="doc_subsection">
1491 <a name="ccxx_derived_types">C/C++ derived types</a>
1492</div>
1493
1494<div class="doc_text">
1495
1496<p>Given the following as an example of C/C++ derived type;</p>
1497
1498<pre>
1499typedef const int *IntPtr;
1500</pre>
1501
1502<p>a C/C++ front-end would generate the following descriptors;</p>
1503
1504<pre>
1505;;
1506;; Define the typedef "IntPtr".
1507;;
1508%<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]1509 uint add(uint 22, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1510 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1511 sbyte* getelementptr ([7 x sbyte]* %str1, int 0, int 0),
1512 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1513 int 1,
1514 uint 0,
1515 uint 0,
1516 uint 0,
1517 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype2</a> to { }*) }, section "llvm.metadata"
1518%str1 = internal constant [7 x sbyte] c"IntPtr\00", section "llvm.metadata"
1519
1520;;
1521;; Define the pointer type.
1522;;
1523%<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]1524 uint add(uint 15, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1525 { }* 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]1526 sbyte* null,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1527 { }* null,
1528 int 0,
1529 uint 32,
1530 uint 32,
1531 uint 0,
1532 { }* 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]1533
1534;;
1535;; Define the const type.
1536;;
1537%<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]1538 uint add(uint 38, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1539 { }* 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]1540 sbyte* null,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1541 { }* null,
1542 int 0,
1543 uint 0,
1544 uint 0,
1545 uint 0,
1546 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype1</a> to { }*) }, section "llvm.metadata"
1547
1548;;
1549;; Define the int type.
1550;;
1551%<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]1552 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1553 { }* 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]1554 sbyte* getelementptr ([4 x sbyte]* %str2, int 0, int 0),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1555 { }* null,
1556 int 0,
1557 uint 32,
1558 uint 32,
1559 uint 0,
1560 uint 5 }, section "llvm.metadata"
Jim Laskey4d9b10b2006-03-14 18:50:50 +0000[diff] [blame]1561%str2 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1562</pre>
1563
1564</div>
1565
1566<!-- ======================================================================= -->
1567<div class="doc_subsection">
1568 <a name="ccxx_composite_types">C/C++ struct/union types</a>
1569</div>
1570
1571<div class="doc_text">
1572
1573<p>Given the following as an example of C/C++ struct type;</p>
1574
1575<pre>
1576struct Color {
1577 unsigned Red;
1578 unsigned Green;
1579 unsigned Blue;
1580};
1581</pre>
1582
1583<p>a C/C++ front-end would generate the following descriptors;</p>
1584
1585<pre>
1586;;
1587;; Define basic type for unsigned int.
1588;;
1589%<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]1590 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1591 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1592 sbyte* getelementptr ([13 x sbyte]* %str1, int 0, int 0),
1593 { }* null,
1594 int 0,
1595 uint 32,
1596 uint 32,
1597 uint 0,
1598 uint 7 }, section "llvm.metadata"
1599%str1 = internal constant [13 x sbyte] c"unsigned int\00", section "llvm.metadata"
1600
1601;;
1602;; Define composite type for struct Color.
1603;;
1604%<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]1605 uint add(uint 19, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1606 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1607 sbyte* getelementptr ([6 x sbyte]* %str2, int 0, int 0),
1608 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1609 int 1,
1610 uint 96,
1611 uint 32,
1612 uint 0,
Jim Laskeyf8a01a92006-06-15 20:51:43 +0000[diff] [blame]1613 { }* null,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1614 { }* cast ([3 x { }*]* %llvm.dbg.array to { }*) }, section "llvm.metadata"
1615%str2 = internal constant [6 x sbyte] c"Color\00", section "llvm.metadata"
1616
1617;;
1618;; Define the Red field.
1619;;
1620%<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]1621 uint add(uint 13, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1622 { }* null,
1623 sbyte* getelementptr ([4 x sbyte]* %str3, int 0, int 0),
1624 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1625 int 2,
1626 uint 32,
1627 uint 32,
1628 uint 0,
1629 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
1630%str3 = internal constant [4 x sbyte] c"Red\00", section "llvm.metadata"
1631
1632;;
1633;; Define the Green field.
1634;;
1635%<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]1636 uint add(uint 13, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1637 { }* null,
1638 sbyte* getelementptr ([6 x sbyte]* %str4, int 0, int 0),
1639 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1640 int 3,
1641 uint 32,
1642 uint 32,
1643 uint 32,
1644 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
1645%str4 = internal constant [6 x sbyte] c"Green\00", section "llvm.metadata"
1646
1647;;
1648;; Define the Blue field.
1649;;
1650%<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]1651 uint add(uint 13, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1652 { }* null,
1653 sbyte* getelementptr ([5 x sbyte]* %str5, int 0, int 0),
1654 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1655 int 4,
1656 uint 32,
1657 uint 32,
1658 uint 64,
1659 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
1660%str5 = internal constant [5 x sbyte] c"Blue\00", section "llvm.metadata"
1661
1662;;
1663;; Define the array of fields used by the composite type Color.
1664;;
1665%llvm.dbg.array = internal constant [3 x { }*] [
1666 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype1</a> to { }*),
1667 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype2</a> to { }*),
1668 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype3</a> to { }*) ], section "llvm.metadata"
1669</pre>
1670
1671</div>
1672
1673<!-- ======================================================================= -->
1674<div class="doc_subsection">
1675 <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
1676</div>
1677
1678<div class="doc_text">
1679
1680<p>Given the following as an example of C/C++ enumeration type;</p>
1681
1682<pre>
1683enum Trees {
1684 Spruce = 100,
1685 Oak = 200,
1686 Maple = 300
1687};
1688</pre>
1689
1690<p>a C/C++ front-end would generate the following descriptors;</p>
1691
1692<pre>
1693;;
1694;; Define composite type for enum Trees
1695;;
1696%<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]1697 uint add(uint 4, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1698 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1699 sbyte* getelementptr ([6 x sbyte]* %str1, int 0, int 0),
1700 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1701 int 1,
1702 uint 32,
1703 uint 32,
1704 uint 0,
1705 { }* null,
1706 { }* cast ([3 x { }*]* %llvm.dbg.array to { }*) }, section "llvm.metadata"
1707%str1 = internal constant [6 x sbyte] c"Trees\00", section "llvm.metadata"
1708
1709;;
1710;; Define Spruce enumerator.
1711;;
1712%<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]1713 uint add(uint 40, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1714 sbyte* getelementptr ([7 x sbyte]* %str2, int 0, int 0),
1715 int 100 }, section "llvm.metadata"
1716%str2 = internal constant [7 x sbyte] c"Spruce\00", section "llvm.metadata"
1717
1718;;
1719;; Define Oak enumerator.
1720;;
1721%<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]1722 uint add(uint 40, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1723 sbyte* getelementptr ([4 x sbyte]* %str3, int 0, int 0),
1724 int 200 }, section "llvm.metadata"
1725%str3 = internal constant [4 x sbyte] c"Oak\00", section "llvm.metadata"
1726
1727;;
1728;; Define Maple enumerator.
1729;;
1730%<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]1731 uint add(uint 40, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1732 sbyte* getelementptr ([6 x sbyte]* %str4, int 0, int 0),
1733 int 300 }, section "llvm.metadata"
1734%str4 = internal constant [6 x sbyte] c"Maple\00", section "llvm.metadata"
1735
1736;;
1737;; Define the array of enumerators used by composite type Trees.
1738;;
1739%llvm.dbg.array = internal constant [3 x { }*] [
1740 { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator1</a> to { }*),
1741 { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator2</a> to { }*),
1742 { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator3</a> to { }*) ], section "llvm.metadata"
1743</pre>
1744
1745</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1746
1747<!-- *********************************************************************** -->
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1748
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1749<hr>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1750<address>
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1755
1756 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]1757 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1758 Last modified: $Date$
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1759</address>
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