Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 5682aff81906c28a4c603b6e874a0ec4095f2f5e / . / docs / SourceLevelDebugging.html
blob: f644fad822521b323bc11ba74cb80b6bd61bc867 [file] [log] [blame]
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
5 <title>Source Level Debugging with LLVM</title>
6 <link rel="stylesheet" href="llvm.css" type="text/css">
7</head>
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 Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame^]392 sbyte*, ;; Display name (unmangled name if Name is the C++ mangled name)
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]393 { }*, ;; Reference to compile unit where defined
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]394 uint, ;; Line number where defined
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]395 { }*, ;; Reference to type descriptor
396 bool, ;; True if the global is local to compile unit (static)
397 bool, ;; True if the global is defined in the compile unit (not extern)
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]398 { }* ;; Reference to the global variable
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]399 }
400</pre>
401
402<p>These descriptors provide debug information about globals variables. The
403provide details such as name, type and where the variable is defined.</p>
404
405</div>
406
407<!-- ======================================================================= -->
408<div class="doc_subsubsection">
409 <a name="format_subprograms">Subprogram descriptors</a>
410</div>
411
412<div class="doc_text">
413
414<pre>
415 %<a href="#format_subprograms">llvm.dbg.subprogram.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]416 uint, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subprogram)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]417 { }*, ;; 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]418 { }*, ;; Reference to context descriptor
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]419 sbyte*, ;; Name
Jim Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame^]420 sbyte*, ;; Display name (unmangled name if Name is the C++ mangled name)
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]421 { }*, ;; Reference to compile unit where defined
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]422 uint, ;; Line number where defined
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]423 { }*, ;; Reference to type descriptor
424 bool, ;; True if the global is local to compile unit (static)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]425 bool ;; True if the global is defined in the compile unit (not extern)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]426 }
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]427</pre>
428
429<p>These descriptors provide debug information about functions, methods and
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]430subprograms. They provide details such as name, return types and the source
431location where the subprogram is defined.</p>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]432
433</div>
434<!-- ======================================================================= -->
435<div class="doc_subsubsection">
436 <a name="format_blocks">Block descriptors</a>
437</div>
438
439<div class="doc_text">
440
441<pre>
442 %<a href="#format_blocks">llvm.dbg.block</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]443 uint, ;; Tag = 13 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]444 { }* ;; Reference to context descriptor
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]445 }
446</pre>
447
448<p>These descriptors provide debug information about nested blocks within a
449subprogram. The array of member descriptors is used to define local variables
450and deeper nested blocks.</p>
451
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]452</div>
453
454<!-- ======================================================================= -->
455<div class="doc_subsubsection">
456 <a name="format_basic_type">Basic type descriptors</a>
457</div>
458
459<div class="doc_text">
460
461<pre>
462 %<a href="#format_basic_type">llvm.dbg.basictype.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]463 uint, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_base_type)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]464 { }*, ;; Reference to context (typically a compile unit)
465 sbyte*, ;; Name (may be "" for anonymous types)
466 { }*, ;; Reference to compile unit where defined (may be NULL)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]467 uint, ;; Line number where defined (may be 0)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]468 uint, ;; Size in bits
469 uint, ;; Alignment in bits
470 uint, ;; Offset in bits
471 uint ;; Dwarf type encoding
472 }
473</pre>
474
475<p>These descriptors define primitive types used in the code. Example int, bool
476and float. The context provides the scope of the type, which is usually the top
477level. Since basic types are not usually user defined the compile unit and line
478number can be left as NULL and 0. The size, alignment and offset are expressed
479in bits and can be 64 bit values. The alignment is used to round the offset
480when embedded in a <a href="#format_composite_type">composite type</a>
481(example to keep float doubles on 64 bit boundaries.) The offset is the bit
482offset if embedded in a <a href="#format_composite_type">composite
483type</a>.</p>
484
485<p>The type encoding provides the details of the type. The values are typically
486one of the following;</p>
487
488<pre>
489 DW_ATE_address = 1
490 DW_ATE_boolean = 2
491 DW_ATE_float = 4
492 DW_ATE_signed = 5
493 DW_ATE_signed_char = 6
494 DW_ATE_unsigned = 7
495 DW_ATE_unsigned_char = 8
496</pre>
497
498</div>
499
500<!-- ======================================================================= -->
501<div class="doc_subsubsection">
502 <a name="format_derived_type">Derived type descriptors</a>
503</div>
504
505<div class="doc_text">
506
507<pre>
508 %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> = type {
509 uint, ;; Tag (see below)
510 { }*, ;; Reference to context
511 sbyte*, ;; Name (may be "" for anonymous types)
512 { }*, ;; Reference to compile unit where defined (may be NULL)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]513 uint, ;; Line number where defined (may be 0)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]514 uint, ;; Size in bits
515 uint, ;; Alignment in bits
516 uint, ;; Offset in bits
517 { }* ;; Reference to type derived from
518 }
519</pre>
520
521<p>These descriptors are used to define types derived from other types. The
522value of the tag varies depending on the meaning. The following are possible
523tag values;</p>
524
525<pre>
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]526 DW_TAG_formal_parameter = 5
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]527 DW_TAG_member = 13
528 DW_TAG_pointer_type = 15
529 DW_TAG_reference_type = 16
530 DW_TAG_typedef = 22
531 DW_TAG_const_type = 38
532 DW_TAG_volatile_type = 53
533 DW_TAG_restrict_type = 55
534</pre>
535
536<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]537href="#format_composite_type">composite type</a> or <a
538href="#format_subprograms">subprogram</a>. The type of the member is the <a
539href="#format_derived_type">derived type</a>. <tt>DW_TAG_formal_parameter</tt>
540is used to define a member which is a formal argument of a subprogram.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]541
542<p><tt>DW_TAG_typedef</tt> is used to
543provide a name for the derived type.</p>
544
545<p><tt>DW_TAG_pointer_type</tt>,
546<tt>DW_TAG_reference_type</tt>, <tt>DW_TAG_const_type</tt>,
547<tt>DW_TAG_volatile_type</tt> and <tt>DW_TAG_restrict_type</tt> are used to
548qualify the <a href="#format_derived_type">derived type</a>. </p>
549
550<p><a href="#format_derived_type">Derived type</a> location can be determined
551from the compile unit and line number. The size, alignment and offset are
552expressed in bits and can be 64 bit values. The alignment is used to round the
553offset when embedded in a <a href="#format_composite_type">composite type</a>
554(example to keep float doubles on 64 bit boundaries.) The offset is the bit
555offset if embedded in a <a href="#format_composite_type">composite
556type</a>.</p>
557
558<p>Note that the <tt>void *</tt> type is expressed as a
559<tt>llvm.dbg.derivedtype.type</tt> with tag of <tt>DW_TAG_pointer_type</tt> and
560NULL derived type.</p>
561
562</div>
563
564<!-- ======================================================================= -->
565<div class="doc_subsubsection">
566 <a name="format_composite_type">Composite type descriptors</a>
567</div>
568
569<div class="doc_text">
570
571<pre>
572 %<a href="#format_composite_type">llvm.dbg.compositetype.type</a> = type {
573 uint, ;; Tag (see below)
574 { }*, ;; Reference to context
575 sbyte*, ;; Name (may be "" for anonymous types)
576 { }*, ;; Reference to compile unit where defined (may be NULL)
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]577 uint, ;; Line number where defined (may be 0)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]578 uint, ;; Size in bits
579 uint, ;; Alignment in bits
580 uint, ;; Offset in bits
581 { }* ;; Reference to array of member descriptors
582 }
583</pre>
584
585<p>These descriptors are used to define types that are composed of 0 or more
586elements. The value of the tag varies depending on the meaning. The following
587are possible tag values;</p>
588
589<pre>
590 DW_TAG_array_type = 1
591 DW_TAG_enumeration_type = 4
592 DW_TAG_structure_type = 19
593 DW_TAG_union_type = 23
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]594 DW_TAG_vector_type = 259
Jim Laskey094ee722006-06-20 21:13:20 +0000[diff] [blame]595 DW_TAG_subroutine_type = 46
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]596 DW_TAG_inheritance = 26
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]597</pre>
598
Jim Laskeyf8a01a92006-06-15 20:51:43 +0000[diff] [blame]599<p>The vector flag indicates that an array type is a native packed vector.</p>
600
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]601<p>The members of array types (tag = <tt>DW_TAG_array_type</tt>) or vector types
602(tag = <tt>DW_TAG_vector_type</tt>) are <a href="#format_subrange">subrange
603descriptors</a>, each representing the range of subscripts at that level of
604indexing.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]605
606<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
607<a href="#format_enumeration">enumerator descriptors</a>, each representing the
608definition of enumeration value
609for the set.</p>
610
611<p>The members of structure (tag = <tt>DW_TAG_structure_type</tt>) or union (tag
612= <tt>DW_TAG_union_type</tt>) types are any one of the <a
613href="#format_basic_type">basic</a>, <a href="#format_derived_type">derived</a>
614or <a href="#format_composite_type">composite</a> type descriptors, each
615representing a field member of the structure or union.</p>
616
Jim Laskey4a9df242006-08-21 21:21:06 +0000[diff] [blame]617<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
618provide information about base classes, static members and member functions. If
619a member is a <a href="#format_derived_type">derived type descriptor</a> and has
620a tag of <tt>DW_TAG_inheritance</tt>, then the type represents a base class. If
621the member of is a <a href="#format_global_variables">global variable
622descriptor</a> then it represents a static member. And, if the member is a <a
623href="#format_subprograms">subprogram descriptor</a> then it represents a member
624function. For static members and member functions, <tt>getName()</tt> returns
625the members link or the C++ mangled name. <tt>getDisplayName()</tt> the
626simplied version of the name.</p>
627
Jim Laskeyb329fe12006-06-21 11:08:10 +0000[diff] [blame]628<p>The first member of subroutine (tag = <tt>DW_TAG_subroutine_type</tt>)
629type elements is the return type for the subroutine. The remaining
Jim Laskey094ee722006-06-20 21:13:20 +0000[diff] [blame]630elements are the formal arguments to the subroutine.</p>
631
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]632<p><a href="#format_composite_type">Composite type</a> location can be
633determined from the compile unit and line number. The size, alignment and
634offset are expressed in bits and can be 64 bit values. The alignment is used to
635round the offset when embedded in a <a href="#format_composite_type">composite
636type</a> (as an example, to keep float doubles on 64 bit boundaries.) The offset
637is the bit offset if embedded in a <a href="#format_composite_type">composite
638type</a>.</p>
639
640</div>
641
642<!-- ======================================================================= -->
643<div class="doc_subsubsection">
644 <a name="format_subrange">Subrange descriptors</a>
645</div>
646
647<div class="doc_text">
648
649<pre>
650 %<a href="#format_subrange">llvm.dbg.subrange.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]651 uint, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]652 uint, ;; Low value
653 uint ;; High value
654 }
655</pre>
656
657<p>These descriptors are used to define ranges of array subscripts for an array
658<a href="#format_composite_type">composite type</a>. The low value defines the
659lower bounds typically zero for C/C++. The high value is the upper bounds.
660Values are 64 bit. High - low + 1 is the size of the array. If
661low == high the array will be unbounded.</p>
662
663</div>
664
665<!-- ======================================================================= -->
666<div class="doc_subsubsection">
667 <a name="format_enumeration">Enumerator descriptors</a>
668</div>
669
670<div class="doc_text">
671
672<pre>
673 %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> = type {
Jim Laskey7089f452006-06-16 13:14:03 +0000[diff] [blame]674 uint, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_enumerator)
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]675 sbyte*, ;; Name
676 uint ;; Value
677 }
678</pre>
679
680<p>These descriptors are used to define members of an enumeration <a
681href="#format_composite_type">composite type</a>, it associates the name to the
682value.</p>
683
684</div>
685
686<!-- ======================================================================= -->
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]687<div class="doc_subsubsection">
688 <a name="format_variables">Local variables</a>
689</div>
690
691<div class="doc_text">
692<pre>
693 %<a href="#format_variables">llvm.dbg.variable.type</a> = type {
694 uint, ;; Tag (see below)
695 { }*, ;; Context
696 sbyte*, ;; Name
697 { }*, ;; Reference to compile unit where defined
698 uint, ;; Line number where defined
699 { }* ;; Type descriptor
700 }
701</pre>
702
703<p>These descriptors are used to define variables local to a sub program. The
704value of the tag depends on the usage of the variable;</p>
705
706<pre>
707 DW_TAG_auto_variable = 256
708 DW_TAG_arg_variable = 257
709 DW_TAG_return_variable = 258
710</pre>
711
712<p>An auto variable is any variable declared in the body of the function. An
713argument variable is any variable that appears as a formal argument to the
714function. A return variable is used to track the result of a function and has
715no source correspondent.</p>
716
Jim Laskey2d395d92006-03-24 09:20:27 +0000[diff] [blame]717<p>The context is either the subprogram or block where the variable is defined.
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]718Name the source variable name. Compile unit and line indicate where the
719variable was defined. Type descriptor defines the declared type of the
720variable.</p>
721
722</div>
723
724<!-- ======================================================================= -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]725<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]726 <a name="format_common_intrinsics">Debugger intrinsic functions</a>
727</div>
728
729<div class="doc_text">
730
731<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
732provide debug information at various points in generated code.</p>
733
734</div>
735
736<!-- ======================================================================= -->
737<div class="doc_subsubsection">
738 <a name="format_common_stoppoint">llvm.dbg.stoppoint</a>
739</div>
740
741<div class="doc_text">
742<pre>
Jim Laskey108a6382006-03-23 17:58:46 +0000[diff] [blame]743 void %<a href="#format_common_stoppoint">llvm.dbg.stoppoint</a>( uint, uint, { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]744</pre>
745
746<p>This intrinsic is used to provide correspondence between the source file and
747the generated code. The first argument is the line number (base 1), second
748argument si the column number (0 if unknown) and the third argument the source
Jim Laskey108a6382006-03-23 17:58:46 +0000[diff] [blame]749<tt>%<a href="#format_compile_units">llvm.dbg.compile_unit</a>*</tt> cast to a
750<tt>{ }*</tt>. Code following a call to this intrinsic will have been defined
751in close proximity of the line, column and file. This information holds until
752the next call to <tt>%<a
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]753href="#format_common_stoppoint">lvm.dbg.stoppoint</a></tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]754
755</div>
756
757<!-- ======================================================================= -->
758<div class="doc_subsubsection">
759 <a name="format_common_func_start">llvm.dbg.func.start</a>
760</div>
761
762<div class="doc_text">
763<pre>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]764 void %<a href="#format_common_func_start">llvm.dbg.func.start</a>( { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]765</pre>
766
767<p>This intrinsic is used to link the debug information in <tt>%<a
768href="#format_subprograms">llvm.dbg.subprogram</a></tt> to the function. It also
769defines the beginning of the function's declarative region (scope.) The
770intrinsic should be called early in the function after the all the alloca
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]771instructions. It should be paired off with a closing <tt>%<a
772href="#format_common_region_end">llvm.dbg.region.end</a></tt>. The function's
773single argument is the <tt>%<a
774href="#format_subprograms">llvm.dbg.subprogram.type</a></tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]775
776</div>
777
778<!-- ======================================================================= -->
779<div class="doc_subsubsection">
780 <a name="format_common_region_start">llvm.dbg.region.start</a>
781</div>
782
783<div class="doc_text">
784<pre>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]785 void %<a href="#format_common_region_start">llvm.dbg.region.start</a>( { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]786</pre>
787
788<p>This intrinsic is used to define the beginning of a declarative scope (ex.
789block) for local language elements. It should be paired off with a closing
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]790<tt>%<a href="#format_common_region_end">llvm.dbg.region.end</a></tt>. The
791function's single argument is the <tt>%<a
792href="#format_blocks">llvm.dbg.block</a></tt> which is starting.</p>
793
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]794
795</div>
796
797<!-- ======================================================================= -->
798<div class="doc_subsubsection">
799 <a name="format_common_region_end">llvm.dbg.region.end</a>
800</div>
801
802<div class="doc_text">
803<pre>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]804 void %<a href="#format_common_region_end">llvm.dbg.region.end</a>( { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]805</pre>
806
807<p>This intrinsic is used to define the end of a declarative scope (ex. block)
808for local language elements. It should be paired off with an opening <tt>%<a
809href="#format_common_region_start">llvm.dbg.region.start</a></tt> or <tt>%<a
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]810href="#format_common_func_start">llvm.dbg.func.start</a></tt>. The function's
811single argument is either the <tt>%<a
812href="#format_blocks">llvm.dbg.block</a></tt> or the <tt>%<a
813href="#format_subprograms">llvm.dbg.subprogram.type</a></tt> which is
814ending.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]815
816</div>
817
818<!-- ======================================================================= -->
819<div class="doc_subsubsection">
820 <a name="format_common_declare">llvm.dbg.declare</a>
821</div>
822
823<div class="doc_text">
824<pre>
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]825 void %<a href="#format_common_declare">llvm.dbg.declare</a>( { } *, { }* )
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]826</pre>
827
Jim Laskey2d395d92006-03-24 09:20:27 +0000[diff] [blame]828<p>This intrinsic provides information about a local element (ex. variable.) The
829first argument is the alloca for the variable, cast to a <tt>{ }*</tt>. The
830second argument is the <tt>%<a
831href="#format_variables">llvm.dbg.variable</a></tt> containing the description
832of the variable, also cast to a <tt>{ }*</tt>.</p>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]833
834</div>
835
836<!-- ======================================================================= -->
837<div class="doc_subsection">
838 <a name="format_common_stoppoints">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]839 Representing stopping points in the source program
840 </a>
841</div>
842
843<div class="doc_text">
844
845<p>LLVM debugger "stop points" are a key part of the debugging representation
846that allows the LLVM to maintain simple semantics for <a
847href="#debugopt">debugging optimized code</a>. The basic idea is that the
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]848front-end inserts calls to the <a
849href="#format_common_stoppoint">%<tt>llvm.dbg.stoppoint</tt></a> intrinsic
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]850function at every point in the program where a debugger should be able to
851inspect the program (these correspond to places a debugger stops when you
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]852"<tt>step</tt>" through it). The front-end can choose to place these as
853fine-grained as it would like (for example, before every subexpression
854evaluated), but it is recommended to only put them after every source statement
855that includes executable code.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]856
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]857<p>Using calls to this intrinsic function to demark legal points for the
858debugger to inspect the program automatically disables any optimizations that
859could potentially confuse debugging information. To non-debug-information-aware
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]860transformations, these calls simply look like calls to an external function,
861which they must assume to do anything (including reading or writing to any part
862of reachable memory). On the other hand, it does not impact many optimizations,
863such as code motion of non-trapping instructions, nor does it impact
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]864optimization of subexpressions, code duplication transformations, or basic-block
865reordering transformations.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]866
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]867</div>
868
869
870<!-- ======================================================================= -->
871<div class="doc_subsection">
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]872 <a name="format_common_lifetime">Object lifetimes and scoping</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]873</div>
874
875<div class="doc_text">
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]876<p>In many languages, the local variables in functions can have their lifetime
877or 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]878example, variables are only live (readable and writable) within the source block
879that they are defined in. In functional languages, values are only readable
880after they have been defined. Though this is a very obvious concept, it is also
881non-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]882and does not want to be tied to a language's scoping rules.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]883
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]884<p>In order to handle this, the LLVM debug format uses the notion of "regions"
885of a function, delineated by calls to intrinsic functions. These intrinsic
886functions define new regions of the program and indicate when the region
887lifetime expires. Consider the following C fragment, for example:</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]8901. void foo() {
8912. int X = ...;
8923. int Y = ...;
8934. {
8945. int Z = ...;
8956. ...
8967. }
8978. ...
8989. }
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]899</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]900
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]901<p>Compiled to LLVM, this function would be represented like this:</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]902
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]903<pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]904void %foo() {
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]905entry:
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]906 %X = alloca int
907 %Y = alloca int
908 %Z = alloca int
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]909
910 ...
911
912 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 )
913
914 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 )
915
916 call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %X, ...)
917 call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %Y, ...)
918
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]919 <i>;; Evaluate expression on line 2, assigning to X.</i>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]920
921 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 )
922
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]923 <i>;; Evaluate expression on line 3, assigning to Y.</i>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]924
925 call void %<a href="#format_common_stoppoint">llvm.region.start</a>()
926 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 )
927 call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %X, ...)
928
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]929 <i>;; Evaluate expression on line 5, assigning to Z.</i>
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]930
931 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 )
932 call void %<a href="#format_common_region_end">llvm.region.end</a>()
933
934 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 )
935
936 call void %<a href="#format_common_region_end">llvm.region.end</a>()
937
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]938 ret void
939}
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]940</pre>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]941
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]942<p>This example illustrates a few important details about the LLVM debugging
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]943information. In particular, it shows how the various intrinsics are applied
944together to allow a debugger to analyze the relationship between statements,
945variable definitions, and the code used to implement the function.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]946
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]947<p>The first intrinsic <tt>%<a
948href="#format_common_func_start">llvm.dbg.func.start</a></tt> provides
949a link with the <a href="#format_subprograms">subprogram descriptor</a>
950containing the details of this function. This call also defines the beginning
951of the function region, bounded by the <tt>%<a
952href="#format_common_region_end">llvm.region.end</a></tt> at the end of
953the function. This region is used to bracket the lifetime of variables declared
954within. For a function, this outer region defines a new stack frame whose
955lifetime ends when the region is ended.</p>
956
957<p>It is possible to define inner regions for short term variables by using the
958%<a href="#format_common_stoppoint"><tt>llvm.region.start</tt></a> and <a
959href="#format_common_region_end"><tt>%llvm.region.end</tt></a> to bound a
960region. The inner region in this example would be for the block containing the
961declaration of Z.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]962
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]963<p>Using regions to represent the boundaries of source-level functions allow
964LLVM interprocedural optimizations to arbitrarily modify LLVM functions without
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]965having to worry about breaking mapping information between the LLVM code and the
966and source-level program. In particular, the inliner requires no modification
967to support inlining with debugging information: there is no explicit correlation
968drawn between LLVM functions and their source-level counterparts (note however,
969that if the inliner inlines all instances of a non-strong-linkage function into
970its caller that it will not be possible for the user to manually invoke the
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]971inlined function from a debugger).</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]972
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]973<p>Once the function has been defined, the <a
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]974href="#format_common_stoppoint"><tt>stopping point</tt></a> corresponding to
975line #2 (column #2) of the function is encountered. At this point in the
976function, <b>no</b> local variables are live. As lines 2 and 3 of the example
977are executed, their variable definitions are introduced into the program using
978%<a href="#format_common_declare"><tt>llvm.dbg.declare</tt></a>, without the
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]979need to specify a new region. These variables do not require new regions to be
980introduced because they go out of scope at the same point in the program: line
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]9819.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]982
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]983<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]984on line 7. For this reason, it is defined within the inner region, which kills
985the availability of <tt>Z</tt> before the code for line 8 is executed. In this
986way, regions can support arbitrary source-language scoping rules, as long as
987they can only be nested (ie, one scope cannot partially overlap with a part of
988another scope).</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]989
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]990<p>It is worth noting that this scoping mechanism is used to control scoping of
991all declarations, not just variable declarations. For example, the scope of a
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]992C++ using declaration is controlled with this couldchange how name lookup is
993performed.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]994
995</div>
996
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]997
998
999<!-- *********************************************************************** -->
1000<div class="doc_section">
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1001 <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1002</div>
Misha Brukman94218a72004-12-09 20:27:37 +0000[diff] [blame]1003<!-- *********************************************************************** -->
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1004
1005<div class="doc_text">
1006
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1007<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]1008that is effectively identical to <a
1009href="http://www.eagercon.com/dwarf/dwarf3std.htm">Dwarf 3.0</a> in terms of
1010information content. This allows code generators to trivially support native
1011debuggers by generating standard dwarf information, and contains enough
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1012information for non-dwarf targets to translate it as needed.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1013
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1014<p>This section describes the forms used to represent C and C++ programs. Other
1015languages could pattern themselves after this (which itself is tuned to
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1016representing programs in the same way that Dwarf 3 does), or they could choose
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1017to provide completely different forms if they don't fit into the Dwarf model.
1018As support for debugging information gets added to the various LLVM
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1019source-language front-ends, the information used should be documented here.</p>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1020
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1021<p>The following sections provide examples of various C/C++ constructs and the
1022debug information that would best describe those constructs.</p>
1023
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1024</div>
1025
1026<!-- ======================================================================= -->
1027<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1028 <a name="ccxx_compile_units">C/C++ source file information</a>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1029</div>
1030
1031<div class="doc_text">
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1032
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1033<p>Given the source files "MySource.cpp" and "MyHeader.h" located in the
1034directory "/Users/mine/sources", the following code;</p>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1035
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1036<pre>
1037#include "MyHeader.h"
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1038
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1039int main(int argc, char *argv[]) {
1040 return 0;
1041}
1042</pre>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1043
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1044<p>a C/C++ front-end would generate the following descriptors;</p>
1045
1046<pre>
1047...
1048;;
1049;; Define types used. In this case we need one for compile unit anchors and one
1050;; for compile units.
1051;;
1052%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
1053%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = type { uint, { }*, uint, uint, sbyte*, sbyte*, sbyte* }
1054...
1055;;
1056;; Define the anchor for compile units. Note that the second field of the
1057;; anchor is 17, which is the same as the tag for compile units
1058;; (17 = DW_TAG_compile_unit.)
1059;;
1060%<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"
1061
1062;;
1063;; Define the compile unit for the source file "/Users/mine/sources/MySource.cpp".
1064;;
1065%<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]1066 uint add(uint 17, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1067 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_units</a> to { }*),
1068 uint 1,
1069 uint 1,
1070 sbyte* getelementptr ([13 x sbyte]* %str1, int 0, int 0),
1071 sbyte* getelementptr ([21 x sbyte]* %str2, int 0, int 0),
1072 sbyte* getelementptr ([33 x sbyte]* %str3, int 0, int 0) }, section "llvm.metadata"
1073
1074;;
1075;; Define the compile unit for the header file "/Users/mine/sources/MyHeader.h".
1076;;
1077%<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]1078 uint add(uint 17, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1079 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_units</a> to { }*),
1080 uint 1,
1081 uint 1,
1082 sbyte* getelementptr ([11 x sbyte]* %str4, int 0, int 0),
1083 sbyte* getelementptr ([21 x sbyte]* %str2, int 0, int 0),
1084 sbyte* getelementptr ([33 x sbyte]* %str3, int 0, int 0) }, section "llvm.metadata"
1085
1086;;
1087;; Define each of the strings used in the compile units.
1088;;
1089%str1 = internal constant [13 x sbyte] c"MySource.cpp\00", section "llvm.metadata";
1090%str2 = internal constant [21 x sbyte] c"/Users/mine/sources/\00", section "llvm.metadata";
1091%str3 = internal constant [33 x sbyte] c"4.0.1 LLVM (LLVM research group)\00", section "llvm.metadata";
1092%str4 = internal constant [11 x sbyte] c"MyHeader.h\00", section "llvm.metadata";
1093...
1094</pre>
1095
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1096</div>
1097
1098<!-- ======================================================================= -->
1099<div class="doc_subsection">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1100 <a name="ccxx_global_variable">C/C++ global variable information</a>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1101</div>
1102
1103<div class="doc_text">
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1104
1105<p>Given an integer global variable declared as follows;</p>
1106
1107<pre>
1108int MyGlobal = 100;
1109</pre>
1110
1111<p>a C/C++ front-end would generate the following descriptors;</p>
1112
1113<pre>
1114;;
1115;; Define types used. One for global variable anchors, one for the global
1116;; variable descriptor, one for the global's basic type and one for the global's
1117;; compile unit.
1118;;
1119%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1120%<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]1121%<a href="#format_basic_type">llvm.dbg.basictype.type</a> = type { uint, { }*, sbyte*, { }*, int, uint, uint, uint, uint }
1122%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = ...
1123...
1124;;
1125;; Define the global itself.
1126;;
1127%MyGlobal = global int 100
1128...
1129;;
1130;; Define the anchor for global variables. Note that the second field of the
1131;; anchor is 52, which is the same as the tag for global variables
1132;; (52 = DW_TAG_variable.)
1133;;
1134%<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"
1135
1136;;
1137;; Define the global variable descriptor. Note the reference to the global
1138;; variable anchor and the global variable itself.
1139;;
1140%<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]1141 uint add(uint 52, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1142 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_global_variables">llvm.dbg.global_variables</a> to { }*),
1143 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1144 sbyte* getelementptr ([9 x sbyte]* %str1, int 0, int 0),
Jim Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame^]1145 sbyte* getelementptr ([1 x sbyte]* %str2, int 0, int 0),
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1146 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1147 uint 1,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1148 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*),
1149 bool false,
1150 bool true,
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1151 { }* cast (int* %MyGlobal to { }*) }, section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1152
1153;;
1154;; Define the basic type of 32 bit signed integer. Note that since int is an
1155;; intrinsic type the source file is NULL and line 0.
1156;;
1157%<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]1158 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1159 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
Jim Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame^]1160 sbyte* getelementptr ([4 x sbyte]* %str3, int 0, int 0),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1161 { }* null,
1162 int 0,
1163 uint 32,
1164 uint 32,
1165 uint 0,
1166 uint 5 }, section "llvm.metadata"
1167
1168;;
1169;; Define the names of the global variable and basic type.
1170;;
1171%str1 = internal constant [9 x sbyte] c"MyGlobal\00", section "llvm.metadata"
Jim Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame^]1172%str2 = internal constant [1 x sbyte] c"\00", section "llvm.metadata"
1173%str3 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1174</pre>
1175
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]1176</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1177
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1178<!-- ======================================================================= -->
1179<div class="doc_subsection">
1180 <a name="ccxx_subprogram">C/C++ function information</a>
1181</div>
1182
1183<div class="doc_text">
1184
1185<p>Given a function declared as follows;</p>
1186
1187<pre>
1188int main(int argc, char *argv[]) {
1189 return 0;
1190}
1191</pre>
1192
1193<p>a C/C++ front-end would generate the following descriptors;</p>
1194
1195<pre>
1196;;
1197;; Define types used. One for subprogram anchors, one for the subprogram
1198;; descriptor, one for the global's basic type and one for the subprogram's
1199;; compile unit.
1200;;
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]1201%<a href="#format_subprograms">llvm.dbg.subprogram.type</a> = type { uint, { }*, { }*, sbyte*, { }*, bool, bool }
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1202%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
1203%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = ...
1204
1205;;
1206;; Define the anchor for subprograms. Note that the second field of the
1207;; anchor is 46, which is the same as the tag for subprograms
1208;; (46 = DW_TAG_subprogram.)
1209;;
1210%<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"
1211
1212;;
1213;; Define the descriptor for the subprogram. TODO - more details.
1214;;
1215%<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]1216 uint add(uint 46, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1217 { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_subprograms">llvm.dbg.subprograms</a> to { }*),
1218 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1219 sbyte* getelementptr ([5 x sbyte]* %str1, int 0, int 0),
Jim Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame^]1220 sbyte* getelementptr ([1 x sbyte]* %str2, int 0, int 0),
Jim Laskey3d11bee2006-03-15 19:10:52 +0000[diff] [blame]1221 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1222 uint 1,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1223 { }* null,
1224 bool false,
Jim Laskey383e0092006-03-23 17:54:33 +0000[diff] [blame]1225 bool true }, section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1226
1227;;
1228;; Define the name of the subprogram.
1229;;
1230%str1 = internal constant [5 x sbyte] c"main\00", section "llvm.metadata"
Jim Laskey5682aff2006-08-21 22:57:31 +0000[diff] [blame^]1231%str2 = internal constant [1 x sbyte] c"\00", section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1232
1233;;
1234;; Define the subprogram itself.
1235;;
1236int %main(int %argc, sbyte** %argv) {
1237...
1238}
1239</pre>
1240
1241</div>
1242
1243<!-- ======================================================================= -->
1244<div class="doc_subsection">
1245 <a name="ccxx_basic_types">C/C++ basic types</a>
1246</div>
1247
1248<div class="doc_text">
1249
1250<p>The following are the basic type descriptors for C/C++ core types;</p>
1251
1252</div>
1253
1254<!-- ======================================================================= -->
1255<div class="doc_subsubsection">
1256 <a name="ccxx_basic_type_bool">bool</a>
1257</div>
1258
1259<div class="doc_text">
1260
1261<pre>
1262%<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]1263 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1264 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1265 sbyte* getelementptr ([5 x sbyte]* %str1, int 0, int 0),
1266 { }* null,
1267 int 0,
1268 uint 32,
1269 uint 32,
1270 uint 0,
1271 uint 2 }, section "llvm.metadata"
1272%str1 = internal constant [5 x sbyte] c"bool\00", section "llvm.metadata"
1273</pre>
1274
1275</div>
1276
1277<!-- ======================================================================= -->
1278<div class="doc_subsubsection">
1279 <a name="ccxx_basic_char">char</a>
1280</div>
1281
1282<div class="doc_text">
1283
1284<pre>
1285%<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]1286 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1287 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1288 sbyte* getelementptr ([5 x sbyte]* %str1, int 0, int 0),
1289 { }* null,
1290 int 0,
1291 uint 8,
1292 uint 8,
1293 uint 0,
1294 uint 6 }, section "llvm.metadata"
1295%str1 = internal constant [5 x sbyte] c"char\00", section "llvm.metadata"
1296</pre>
1297
1298</div>
1299
1300<!-- ======================================================================= -->
1301<div class="doc_subsubsection">
1302 <a name="ccxx_basic_unsigned_char">unsigned char</a>
1303</div>
1304
1305<div class="doc_text">
1306
1307<pre>
1308%<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]1309 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1310 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1311 sbyte* getelementptr ([14 x sbyte]* %str1, int 0, int 0),
1312 { }* null,
1313 int 0,
1314 uint 8,
1315 uint 8,
1316 uint 0,
1317 uint 8 }, section "llvm.metadata"
1318%str1 = internal constant [14 x sbyte] c"unsigned char\00", section "llvm.metadata"
1319</pre>
1320
1321</div>
1322
1323<!-- ======================================================================= -->
1324<div class="doc_subsubsection">
1325 <a name="ccxx_basic_short">short</a>
1326</div>
1327
1328<div class="doc_text">
1329
1330<pre>
1331%<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]1332 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1333 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1334 sbyte* getelementptr ([10 x sbyte]* %str1, int 0, int 0),
1335 { }* null,
1336 int 0,
1337 uint 16,
1338 uint 16,
1339 uint 0,
1340 uint 5 }, section "llvm.metadata"
1341%str1 = internal constant [10 x sbyte] c"short int\00", section "llvm.metadata"
1342</pre>
1343
1344</div>
1345
1346<!-- ======================================================================= -->
1347<div class="doc_subsubsection">
1348 <a name="ccxx_basic_unsigned_short">unsigned short</a>
1349</div>
1350
1351<div class="doc_text">
1352
1353<pre>
1354%<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]1355 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1356 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1357 sbyte* getelementptr ([19 x sbyte]* %str1, int 0, int 0),
1358 { }* null,
1359 int 0,
1360 uint 16,
1361 uint 16,
1362 uint 0,
1363 uint 7 }, section "llvm.metadata"
1364%str1 = internal constant [19 x sbyte] c"short unsigned int\00", section "llvm.metadata"
1365</pre>
1366
1367</div>
1368
1369<!-- ======================================================================= -->
1370<div class="doc_subsubsection">
1371 <a name="ccxx_basic_int">int</a>
1372</div>
1373
1374<div class="doc_text">
1375
1376<pre>
1377%<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]1378 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1379 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1380 sbyte* getelementptr ([4 x sbyte]* %str1, int 0, int 0),
1381 { }* null,
1382 int 0,
1383 uint 32,
1384 uint 32,
1385 uint 0,
1386 uint 5 }, section "llvm.metadata"
1387%str1 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
1388</pre>
1389
1390</div>
1391
1392<!-- ======================================================================= -->
1393<div class="doc_subsubsection">
1394 <a name="ccxx_basic_unsigned_int">unsigned int</a>
1395</div>
1396
1397<div class="doc_text">
1398
1399<pre>
1400%<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]1401 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1402 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1403 sbyte* getelementptr ([13 x sbyte]* %str1, int 0, int 0),
1404 { }* null,
1405 int 0,
1406 uint 32,
1407 uint 32,
1408 uint 0,
1409 uint 7 }, section "llvm.metadata"
1410%str1 = internal constant [13 x sbyte] c"unsigned int\00", section "llvm.metadata"
1411</pre>
1412
1413</div>
1414
1415<!-- ======================================================================= -->
1416<div class="doc_subsubsection">
1417 <a name="ccxx_basic_long_long">long long</a>
1418</div>
1419
1420<div class="doc_text">
1421
1422<pre>
1423%<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]1424 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1425 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1426 sbyte* getelementptr ([14 x sbyte]* %str1, int 0, int 0),
1427 { }* null,
1428 int 0,
1429 uint 64,
1430 uint 64,
1431 uint 0,
1432 uint 5 }, section "llvm.metadata"
1433%str1 = internal constant [14 x sbyte] c"long long int\00", section "llvm.metadata"
1434</pre>
1435
1436</div>
1437
1438<!-- ======================================================================= -->
1439<div class="doc_subsubsection">
1440 <a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
1441</div>
1442
1443<div class="doc_text">
1444
1445<pre>
1446%<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]1447 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1448 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1449 sbyte* getelementptr ([23 x sbyte]* %str1, int 0, int 0),
1450 { }* null,
1451 int 0,
1452 uint 64,
1453 uint 64,
1454 uint 0,
1455 uint 7 }, section "llvm.metadata"
1456%str1 = internal constant [23 x sbyte] c"long long unsigned int\00", section "llvm.metadata"
1457</pre>
1458
1459</div>
1460
1461<!-- ======================================================================= -->
1462<div class="doc_subsubsection">
1463 <a name="ccxx_basic_float">float</a>
1464</div>
1465
1466<div class="doc_text">
1467
1468<pre>
1469%<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]1470 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1471 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1472 sbyte* getelementptr ([6 x sbyte]* %str1, int 0, int 0),
1473 { }* null,
1474 int 0,
1475 uint 32,
1476 uint 32,
1477 uint 0,
1478 uint 4 }, section "llvm.metadata"
1479%str1 = internal constant [6 x sbyte] c"float\00", section "llvm.metadata"
1480</pre>
1481
1482</div>
1483
1484<!-- ======================================================================= -->
1485<div class="doc_subsubsection">
1486 <a name="ccxx_basic_double">double</a>
1487</div>
1488
1489<div class="doc_text">
1490
1491<pre>
1492%<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]1493 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1494 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1495 sbyte* getelementptr ([7 x sbyte]* %str1, int 0, int 0),
1496 { }* null,
1497 int 0,
1498 uint 64,
1499 uint 64,
1500 uint 0,
1501 uint 4 }, section "llvm.metadata"
1502%str1 = internal constant [7 x sbyte] c"double\00", section "llvm.metadata"
1503</pre>
1504
1505</div>
1506
1507<!-- ======================================================================= -->
1508<div class="doc_subsection">
1509 <a name="ccxx_derived_types">C/C++ derived types</a>
1510</div>
1511
1512<div class="doc_text">
1513
1514<p>Given the following as an example of C/C++ derived type;</p>
1515
1516<pre>
1517typedef const int *IntPtr;
1518</pre>
1519
1520<p>a C/C++ front-end would generate the following descriptors;</p>
1521
1522<pre>
1523;;
1524;; Define the typedef "IntPtr".
1525;;
1526%<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]1527 uint add(uint 22, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1528 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1529 sbyte* getelementptr ([7 x sbyte]* %str1, int 0, int 0),
1530 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1531 int 1,
1532 uint 0,
1533 uint 0,
1534 uint 0,
1535 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype2</a> to { }*) }, section "llvm.metadata"
1536%str1 = internal constant [7 x sbyte] c"IntPtr\00", section "llvm.metadata"
1537
1538;;
1539;; Define the pointer type.
1540;;
1541%<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]1542 uint add(uint 15, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1543 { }* 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]1544 sbyte* null,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1545 { }* null,
1546 int 0,
1547 uint 32,
1548 uint 32,
1549 uint 0,
1550 { }* 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]1551
1552;;
1553;; Define the const type.
1554;;
1555%<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]1556 uint add(uint 38, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1557 { }* 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]1558 sbyte* null,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1559 { }* null,
1560 int 0,
1561 uint 0,
1562 uint 0,
1563 uint 0,
1564 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype1</a> to { }*) }, section "llvm.metadata"
1565
1566;;
1567;; Define the int type.
1568;;
1569%<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]1570 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1571 { }* 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]1572 sbyte* getelementptr ([4 x sbyte]* %str2, int 0, int 0),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1573 { }* null,
1574 int 0,
1575 uint 32,
1576 uint 32,
1577 uint 0,
1578 uint 5 }, section "llvm.metadata"
Jim Laskey4d9b10b2006-03-14 18:50:50 +0000[diff] [blame]1579%str2 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1580</pre>
1581
1582</div>
1583
1584<!-- ======================================================================= -->
1585<div class="doc_subsection">
1586 <a name="ccxx_composite_types">C/C++ struct/union types</a>
1587</div>
1588
1589<div class="doc_text">
1590
1591<p>Given the following as an example of C/C++ struct type;</p>
1592
1593<pre>
1594struct Color {
1595 unsigned Red;
1596 unsigned Green;
1597 unsigned Blue;
1598};
1599</pre>
1600
1601<p>a C/C++ front-end would generate the following descriptors;</p>
1602
1603<pre>
1604;;
1605;; Define basic type for unsigned int.
1606;;
1607%<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]1608 uint add(uint 36, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1609 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1610 sbyte* getelementptr ([13 x sbyte]* %str1, int 0, int 0),
1611 { }* null,
1612 int 0,
1613 uint 32,
1614 uint 32,
1615 uint 0,
1616 uint 7 }, section "llvm.metadata"
1617%str1 = internal constant [13 x sbyte] c"unsigned int\00", section "llvm.metadata"
1618
1619;;
1620;; Define composite type for struct Color.
1621;;
1622%<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]1623 uint add(uint 19, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]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 sbyte* getelementptr ([6 x sbyte]* %str2, int 0, int 0),
1626 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1627 int 1,
1628 uint 96,
1629 uint 32,
1630 uint 0,
Jim Laskeyf8a01a92006-06-15 20:51:43 +0000[diff] [blame]1631 { }* null,
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1632 { }* cast ([3 x { }*]* %llvm.dbg.array to { }*) }, section "llvm.metadata"
1633%str2 = internal constant [6 x sbyte] c"Color\00", section "llvm.metadata"
1634
1635;;
1636;; Define the Red field.
1637;;
1638%<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]1639 uint add(uint 13, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1640 { }* null,
1641 sbyte* getelementptr ([4 x sbyte]* %str3, int 0, int 0),
1642 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1643 int 2,
1644 uint 32,
1645 uint 32,
1646 uint 0,
1647 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
1648%str3 = internal constant [4 x sbyte] c"Red\00", section "llvm.metadata"
1649
1650;;
1651;; Define the Green field.
1652;;
1653%<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]1654 uint add(uint 13, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1655 { }* null,
1656 sbyte* getelementptr ([6 x sbyte]* %str4, int 0, int 0),
1657 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1658 int 3,
1659 uint 32,
1660 uint 32,
1661 uint 32,
1662 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
1663%str4 = internal constant [6 x sbyte] c"Green\00", section "llvm.metadata"
1664
1665;;
1666;; Define the Blue field.
1667;;
1668%<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]1669 uint add(uint 13, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1670 { }* null,
1671 sbyte* getelementptr ([5 x sbyte]* %str5, int 0, int 0),
1672 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1673 int 4,
1674 uint 32,
1675 uint 32,
1676 uint 64,
1677 { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
1678%str5 = internal constant [5 x sbyte] c"Blue\00", section "llvm.metadata"
1679
1680;;
1681;; Define the array of fields used by the composite type Color.
1682;;
1683%llvm.dbg.array = internal constant [3 x { }*] [
1684 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype1</a> to { }*),
1685 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype2</a> to { }*),
1686 { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype3</a> to { }*) ], section "llvm.metadata"
1687</pre>
1688
1689</div>
1690
1691<!-- ======================================================================= -->
1692<div class="doc_subsection">
1693 <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
1694</div>
1695
1696<div class="doc_text">
1697
1698<p>Given the following as an example of C/C++ enumeration type;</p>
1699
1700<pre>
1701enum Trees {
1702 Spruce = 100,
1703 Oak = 200,
1704 Maple = 300
1705};
1706</pre>
1707
1708<p>a C/C++ front-end would generate the following descriptors;</p>
1709
1710<pre>
1711;;
1712;; Define composite type for enum Trees
1713;;
1714%<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]1715 uint add(uint 4, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1716 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1717 sbyte* getelementptr ([6 x sbyte]* %str1, int 0, int 0),
1718 { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
1719 int 1,
1720 uint 32,
1721 uint 32,
1722 uint 0,
1723 { }* null,
1724 { }* cast ([3 x { }*]* %llvm.dbg.array to { }*) }, section "llvm.metadata"
1725%str1 = internal constant [6 x sbyte] c"Trees\00", section "llvm.metadata"
1726
1727;;
1728;; Define Spruce enumerator.
1729;;
1730%<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]1731 uint add(uint 40, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1732 sbyte* getelementptr ([7 x sbyte]* %str2, int 0, int 0),
1733 int 100 }, section "llvm.metadata"
1734%str2 = internal constant [7 x sbyte] c"Spruce\00", section "llvm.metadata"
1735
1736;;
1737;; Define Oak enumerator.
1738;;
1739%<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]1740 uint add(uint 40, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1741 sbyte* getelementptr ([4 x sbyte]* %str3, int 0, int 0),
1742 int 200 }, section "llvm.metadata"
1743%str3 = internal constant [4 x sbyte] c"Oak\00", section "llvm.metadata"
1744
1745;;
1746;; Define Maple enumerator.
1747;;
1748%<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]1749 uint add(uint 40, uint 262144),
Jim Laskeycec12a52006-03-14 18:08:46 +0000[diff] [blame]1750 sbyte* getelementptr ([6 x sbyte]* %str4, int 0, int 0),
1751 int 300 }, section "llvm.metadata"
1752%str4 = internal constant [6 x sbyte] c"Maple\00", section "llvm.metadata"
1753
1754;;
1755;; Define the array of enumerators used by composite type Trees.
1756;;
1757%llvm.dbg.array = internal constant [3 x { }*] [
1758 { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator1</a> to { }*),
1759 { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator2</a> to { }*),
1760 { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator3</a> to { }*) ], section "llvm.metadata"
1761</pre>
1762
1763</div>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1764
1765<!-- *********************************************************************** -->
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1766
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1767<hr>
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1768<address>
1769 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
1770 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
1771 <a href="http://validator.w3.org/check/referer"><img
1772 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
1773
1774 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]1775 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1776 Last modified: $Date$
Misha Brukman82873732004-05-12 19:21:57 +0000[diff] [blame]1777</address>
Chris Lattnerbdfb3392004-01-05 05:06:33 +0000[diff] [blame]1778
1779</body>
1780</html>