<div class="doc_title">Source Level Debugging with LLVM</div>
-<table border="0" width="100%">
-<tr>
-<td valign="top">
+<table class="layout" style="width:100%">
+ <tr class="layout">
+ <td class="left">
<ul>
-
<li><a href="#introduction">Introduction</a>
<ol>
<li><a href="#phil">Philosophy behind LLVM debugging information</a></li>
+ <li><a href="#consumers">Debug information consumers</a></li>
<li><a href="#debugopt">Debugging optimized code</a></li>
- <li><a href="#future">Future work</a></li>
- </ol></li>
- <li><a href="#llvm-db">Using the <tt>llvm-db</tt> tool</a>
- <ol>
- <li><a href="#limitations">Limitations of <tt>llvm-db</tt></a></li>
- <li><a href="#sample">A sample <tt>llvm-db</tt> session</a></li>
- <li><a href="#startup">Starting the debugger</a></li>
- <li><a href="#commands">Commands recognized by the debugger</a></li>
</ol></li>
-
- <li><a href="#architecture">Architecture of the LLVM debugger</a>
- <ol>
- <li><a href="#arch_debugger">The Debugger and InferiorProcess classes</a></li>
- <li><a href="#arch_info">The RuntimeInfo, ProgramInfo, and SourceLanguage classes</a></li>
- <li><a href="#arch_llvm-db">The <tt>llvm-db</tt> tool</a></li>
- <li><a href="#arch_todo">Short-term TODO list</a></li>
- </ol></li>
-
<li><a href="#format">Debugging information format</a>
<ol>
- <li><a href="#format_common_anchors">Anchors for global objects</a></li>
- <li><a href="#format_common_stoppoint">Representing stopping points in the source program</a></li>
- <li><a href="#format_common_lifetime">Object lifetimes and scoping</a></li>
- <li><a href="#format_common_descriptors">Object descriptor formats</a>
+ <li><a href="#debug_info_descriptors">Debug information descriptors</a>
<ul>
- <li><a href="#format_common_source_files">Representation of source files</a></li>
- <li><a href="#format_common_program_objects">Representation of program objects</a></li>
- <li><a href="#format_common_object_contexts">Program object contexts</a></li>
+ <li><a href="#format_anchors">Anchor descriptors</a></li>
+ <li><a href="#format_compile_units">Compile unit descriptors</a></li>
+ <li><a href="#format_global_variables">Global variable descriptors</a></li>
+ <li><a href="#format_subprograms">Subprogram descriptors</a></li>
+ <li><a href="#format_blocks">Block descriptors</a></li>
+ <li><a href="#format_basic_type">Basic type descriptors</a></li>
+ <li><a href="#format_derived_type">Derived type descriptors</a></li>
+ <li><a href="#format_composite_type">Composite type descriptors</a></li>
+ <li><a href="#format_subrange">Subrange descriptors</a></li>
+ <li><a href="#format_enumeration">Enumerator descriptors</a></li>
+ <li><a href="#format_variables">Local variables</a></li>
</ul></li>
- <li><a href="#format_common_intrinsics">Debugger intrinsic functions</a></li>
- <li><a href="#format_common_tags">Values for debugger tags</a></li>
+ <li><a href="#format_common_intrinsics">Debugger intrinsic functions</a>
+ <ul>
+ <li><a href="#format_common_stoppoint">llvm.dbg.stoppoint</a></li>
+ <li><a href="#format_common_func_start">llvm.dbg.func.start</a></li>
+ <li><a href="#format_common_region_start">llvm.dbg.region.start</a></li>
+ <li><a href="#format_common_region_end">llvm.dbg.region.end</a></li>
+ <li><a href="#format_common_declare">llvm.dbg.declare</a></li>
+ </ul></li>
+ <li><a href="#format_common_stoppoints">Representing stopping points in the
+ source program</a></li>
</ol></li>
<li><a href="#ccxx_frontend">C/C++ front-end specific debug information</a>
<ol>
- <li><a href="#ccxx_pse">Program Scope Entries</a>
- <ul>
- <li><a href="#ccxx_compilation_units">Compilation unit entries</a></li>
- <li><a href="#ccxx_modules">Module, namespace, and importing entries</a></li>
- </ul></li>
- <li><a href="#ccxx_dataobjects">Data objects (program variables)</a></li>
+ <li><a href="#ccxx_compile_units">C/C++ source file information</a></li>
+ <li><a href="#ccxx_global_variable">C/C++ global variable information</a></li>
+ <li><a href="#ccxx_subprogram">C/C++ function information</a></li>
+ <li><a href="#ccxx_basic_types">C/C++ basic types</a></li>
+ <li><a href="#ccxx_derived_types">C/C++ derived types</a></li>
+ <li><a href="#ccxx_composite_types">C/C++ struct/union types</a></li>
+ <li><a href="#ccxx_enumeration_types">C/C++ enumeration types</a></li>
</ol></li>
</ul>
</td>
-<td align="right" valign="top">
+<td class="right">
<img src="img/venusflytrap.jpg" alt="A leafy and green bug eater" width="247"
height="369">
</td>
-</tr>
-</table>
+</tr></table>
+<div class="doc_author">
+ <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
+ and <a href="mailto:jlaskey@mac.com">Jim Laskey</a></p>
+</div>
+
+<!-- *********************************************************************** -->
+<div class="doc_section"><a name="introduction">Introduction</a></div>
<!-- *********************************************************************** -->
-<div class="doc_section"><a name="introduction">Introduction</a></div> <!--
-*********************************************************************** -->
<div class="doc_text">
<p>This document is the central repository for all information pertaining to
-debug information in LLVM. It describes the <a href="#llvm-db">user
-interface</a> for the <a href="CommandGuide/llvm-db.html"><tt>llvm-db</tt>
-tool</a>, which provides a powerful <a href="#llvm-db">source-level debugger</a>
-to users of LLVM-based compilers. It then describes the <a
-href="#architecture">various components</a> that make up the debugger and the
-libraries which future clients may use. Finally, it describes the <a
-href="#format">actual format that the LLVM debug information</a> takes,
-which is useful for those interested in creating front-ends or dealing directly
-with the information.</p>
+debug information in LLVM. It describes the <a href="#format">actual format
+that the LLVM debug information</a> takes, which is useful for those interested
+in creating front-ends or dealing directly with the information. Further, this
+document provides specifc examples of what debug information for C/C++.</p>
</div>
currently uses working draft 7 of the <a
href="http://www.eagercon.com/dwarf/dwarf3std.htm">Dwarf 3 standard</a>).</p>
-<p>When a program is debugged, the debugger interacts with the user and turns
-the stored debug information into source-language specific information. As
-such, the debugger must be aware of the source-language, and is thus tied to a
-specific language of family of languages. The <a href="#llvm-db">LLVM
-debugger</a> is designed to be modular in its support for source-languages.</p>
+<p>When a program is being debugged, a debugger interacts with the user and
+turns the stored debug information into source-language specific information.
+As such, a debugger must be aware of the source-language, and is thus tied to
+a specific language of family of languages.</p>
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="consumers">Debug information consumers</a>
+</div>
+
+<div class="doc_text">
+<p>The role of debug information is to provide meta information normally
+stripped away during the compilation process. This meta information provides an
+llvm user a relationship between generated code and the original program source
+code.</p>
+
+<p>Currently, debug information is consumed by the DwarfWriter to produce dwarf
+information used by the gdb debugger. Other targets could use the same
+information to produce stabs or other debug forms.</p>
+
+<p>It would also be reasonable to use debug information to feed profiling tools
+for analysis of generated code, or, tools for reconstructing the original source
+from generated code.</p>
+
+<p>TODO - expound a bit more.</p>
+
+</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<p>Basically, the debug information allows you to compile a program with
"<tt>-O0 -g</tt>" and get full debug information, allowing you to arbitrarily
-modify the program as it executes from the debugger. Compiling a program with
+modify the program as it executes from a debugger. Compiling a program with
"<tt>-O3 -g</tt>" gives you full debug information that is always available and
accurate for reading (e.g., you get accurate stack traces despite tail call
elimination and inlining), but you might lose the ability to modify the program
</div>
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="future">Future work</a>
+<!-- *********************************************************************** -->
+<div class="doc_section">
+ <a name="format">Debugging information format</a>
</div>
+<!-- *********************************************************************** -->
<div class="doc_text">
-<p>There are several important extensions that could be eventually added to the
-LLVM debugger. The most important extension would be to upgrade the LLVM code
-generators to support debugging information. This would also allow, for
-example, the X86 code generator to emit native objects that contain debugging
-information consumable by traditional source-level debuggers like GDB or
-DBX.</p>
-<p>Additionally, LLVM optimizations can be upgraded to incrementally update the
-debugging information, <a href="#commands">new commands</a> can be added to the
-debugger, and thread support could be added to the debugger.</p>
+<p>LLVM debugging information has been carefully designed to make it possible
+for the optimizer to optimize the program and debugging information without
+necessarily having to know anything about debugging information. In particular,
+the global constant merging pass automatically eliminates duplicated debugging
+information (often caused by header files), the global dead code elimination
+pass automatically deletes debugging information for a function if it decides to
+delete the function, and the linker eliminates debug information when it merges
+<tt>linkonce</tt> functions.</p>
+
+<p>To do this, most of the debugging information (descriptors for types,
+variables, functions, source files, etc) is inserted by the language front-end
+in the form of LLVM global variables. These LLVM global variables are no
+different from any other global variables, except that they have a web of LLVM
+intrinsic functions that point to them. If the last references to a particular
+piece of debugging information are deleted (for example, by the
+<tt>-globaldce</tt> pass), the extraneous debug information will automatically
+become dead and be removed by the optimizer.</p>
-<p>The "SourceLanguage" modules provided by <tt>llvm-db</tt> could be
-substantially improved to provide good support for C++ language features like
-namespaces and scoping rules.</p>
+<p>Debug information is designed to be agnostic about the target debugger and
+debugging information representation (e.g. DWARF/Stabs/etc). It uses a generic
+machine debug information pass to decode the information that represents
+variables, types, functions, namespaces, etc: this allows for arbitrary
+source-language semantics and type-systems to be used, as long as there is a
+module written for the target debugger to interpret the information. In
+addition, debug global variables are declared in the <tt>"llvm.metadata"</tt>
+section. All values declared in this section are stripped away after target
+debug information is constructed and before the program object is emitted.</p>
-<p>After working with the debugger for a while, perhaps the nicest improvement
-would be to add some sort of line editor, such as GNU readline (but one that is
-compatible with the LLVM license).</p>
+<p>To provide basic functionality, the LLVM debugger does have to make some
+assumptions about the source-level language being debugged, though it keeps
+these to a minimum. The only common features that the LLVM debugger assumes
+exist are <a href="#format_compile_units">source files</a>, and <a
+href="#format_global_variables">program objects</a>. These abstract objects are
+used by a debugger to form stack traces, show information about local
+variables, etc.</p>
-<p>For someone so inclined, it should be straight-forward to write different
-front-ends for the LLVM debugger, as the LLVM debugging engine is cleanly
-separated from the <tt>llvm-db</tt> front-end. A new LLVM GUI debugger or IDE
-would be nice. :)</p>
+<p>This section of the documentation first describes the representation aspects
+common to any source-language. The <a href="#ccxx_frontend">next section</a>
+describes the data layout conventions used by the C and C++ front-ends.</p>
</div>
-<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="llvm-db">Using the <tt>llvm-db</tt> tool</a>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="debug_info_descriptors">Debug information descriptors</a>
</div>
-<!-- *********************************************************************** -->
<div class="doc_text">
+<p>In consideration of the complexity and volume of debug information, LLVM
+provides a specification for well formed debug global variables. The constant
+value of each of these globals is one of a limited set of structures, known as
+debug descriptors.</p>
+
+<p>Consumers of LLVM debug information expect the descriptors for program
+objects to start in a canonical format, but the descriptors can include
+additional information appended at the end that is source-language specific. All
+LLVM debugging information is versioned, allowing backwards compatibility in the
+case that the core structures need to change in some way. Also, all debugging
+information objects start with a tag to indicate what type of object it is. The
+source-language is allowed to define its own objects, by using unreserved tag
+numbers. We recommend using with tags in the range 0x1000 thru 0x2000 (there is
+a defined enum DW_TAG_user_base = 0x1000.)</p>
+
+<p>The fields of debug descriptors used internally by LLVM (MachineModuleInfo)
+are restricted to only the simple data types <tt>int</tt>, <tt>uint</tt>,
+<tt>bool</tt>, <tt>float</tt>, <tt>double</tt>, <tt>sbyte*</tt> and <tt> { }*
+</tt>. References to arbitrary values are handled using a <tt> { }* </tt> and a
+cast to <tt> { }* </tt> expression; typically references to other field
+descriptors, arrays of descriptors or global variables.</p>
+
+<pre>
+ %llvm.dbg.object.type = type {
+ uint, ;; A tag
+ ...
+ }
+</pre>
-<p>The <tt>llvm-db</tt> tool provides a GDB-like interface for source-level
-debugging of programs. This tool provides many standard commands for inspecting
-and modifying the program as it executes, loading new programs, single stepping,
-placing breakpoints, etc. This section describes how to use the debugger.</p>
+<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
+<tt>uint</tt> containing a tag value identifying the content of the descriptor.
+The remaining fields are specific to the descriptor. The values of tags are
+loosely bound to the tag values of Dwarf information entries. However, that
+does not restrict the use of the information supplied to Dwarf targets. To
+facilitate versioning of debug information, the tag is augmented with the
+current debug version (LLVMDebugVersion = 4 << 16 or 0x40000 or 262144.)</a></p>
-<p><tt>llvm-db</tt> has been designed to be as similar to GDB in its user
-interface as possible. This should make it extremely easy to learn
-<tt>llvm-db</tt> if you already know <tt>GDB</tt>. In general, <tt>llvm-db</tt>
-provides the subset of GDB commands that are applicable to LLVM debugging users.
-If there is a command missing that make a reasonable amount of sense within the
-<a href="#limitations">limitations of <tt>llvm-db</tt></a>, please report it as
-a bug or, better yet, submit a patch to add it. :)</p>
+<p>The details of the various descriptors follow.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="limitations">Limitations of <tt>llvm-db</tt></a>
+<div class="doc_subsubsection">
+ <a name="format_anchors">Anchor descriptors</a>
</div>
<div class="doc_text">
-<p><tt>llvm-db</tt> is designed to be modular and easy to extend. This
-extensibility was key to getting the debugger up-and-running quickly, because we
-can start with simple-but-unsophisicated implementations of various components.
-Because of this, it is currently missing many features, though they should be
-easy to add over time (patches welcomed!). The biggest inherent limitations of
-<tt>llvm-db</tt> are currently due to extremely simple <a
-href="#arch_debugger">debugger backend</a> (implemented in
-"lib/Debugger/UnixLocalInferiorProcess.cpp") which is designed to work without
-any cooperation from the code generators. Because it is so simple, it suffers
-from the following inherent limitations:</p>
+<pre>
+ %<a href="#format_anchors">llvm.dbg.anchor.type</a> = type {
+ uint, ;; Tag = 0 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
+ uint ;; Tag of descriptors grouped by the anchor
+ }
+</pre>
-<ul>
+<p>One important aspect of the LLVM debug representation is that it allows the
+LLVM debugger to efficiently index all of the global objects without having the
+scan the program. To do this, all of the global objects use "anchor"
+descriptors with designated names. All of the global objects of a particular
+type (e.g., compile units) contain a pointer to the anchor. This pointer allows
+a debugger to use def-use chains to find all global objects of that type.</p>
-<li>Running a program in <tt>llvm-db</tt> is a bit slower than running it with
-<tt>lli</tt> (i.e., in the JIT).</li>
+<p>The following names are recognized as anchors by LLVM:</p>
-<li>Inspection of the target hardware is not supported. This means that you
-cannot, for example, print the contents of X86 registers.</li>
+<pre>
+ %<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
+ %<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
+ %<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
+</pre>
-<li>Inspection of LLVM code is not supported. This means that you cannot print
-the contents of arbitrary LLVM values, or use commands such as <tt>stepi</tt>.
-This also means that you cannot debug code without debug information.</li>
+<p>Using anchors in this way (where the compile unit descriptor points to the
+anchors, as opposed to having a list of compile unit descriptors) allows for the
+standard dead global elimination and merging passes to automatically remove
+unused debugging information. If the globals were kept track of through lists,
+there would always be an object pointing to the descriptors, thus would never be
+deleted.</p>
-<li>Portions of the debugger run in the same address space as the program being
-debugged. This means that memory corruption by the program could trample on
-portions of the debugger.</li>
+</div>
-<li>Attaching to existing processes and core files is not currently
-supported.</li>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_compile_units">Compile unit descriptors</a>
+</div>
-</ul>
+<div class="doc_text">
-<p>That said, the debugger is still quite useful, and all of these limitations
-can be eliminated by integrating support for the debugger into the code
-generators, and writing a new <a href="#arch_debugger">InferiorProcess</a>
-subclass to use it. See the <a href="#future">future work</a> section for ideas
-of how to extend the LLVM debugger despite these limitations.</p>
+<pre>
+ %<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = type {
+ uint, ;; Tag = 17 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_compile_unit)
+ { }*, ;; Compile unit anchor = cast = (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_units</a> to { }*)
+ uint, ;; Dwarf language identifier (ex. DW_LANG_C89)
+ sbyte*, ;; Source file name
+ sbyte*, ;; Source file directory (includes trailing slash)
+ sbyte* ;; Producer (ex. "4.0.1 LLVM (LLVM research group)")
+ }
+</pre>
-</div>
+<p>These descriptors contain a source language ID for the file (we use the Dwarf
+3.0 ID numbers, such as <tt>DW_LANG_C89</tt>, <tt>DW_LANG_C_plus_plus</tt>,
+<tt>DW_LANG_Cobol74</tt>, etc), three strings describing the filename, working
+directory of the compiler, and an identifier string for the compiler that
+produced it.</p>
+<p> Compile unit descriptors provide the root context for objects declared in a
+specific source file. Global variables and top level functions would be defined
+using this context. Compile unit descriptors also provide context for source
+line correspondence.</p>
+
+</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="sample">A sample <tt>llvm-db</tt> session</a>
+<div class="doc_subsubsection">
+ <a name="format_global_variables">Global variable descriptors</a>
</div>
<div class="doc_text">
-<p>TODO: this is obviously lame, when more is implemented, this can be much
-better.</p>
+<pre>
+ %<a href="#format_global_variables">llvm.dbg.global_variable.type</a> = type {
+ uint, ;; Tag = 52 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_variable)
+ { }*, ;; Global variable anchor = cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_global_variables">llvm.dbg.global_variables</a> to { }*),
+ { }*, ;; Reference to context descriptor
+ sbyte*, ;; Name
+ sbyte*, ;; Display name (fully qualified C++ name)
+ sbyte*, ;; MIPS linkage name (for C++)
+ { }*, ;; Reference to compile unit where defined
+ uint, ;; Line number where defined
+ { }*, ;; Reference to type descriptor
+ bool, ;; True if the global is local to compile unit (static)
+ bool, ;; True if the global is defined in the compile unit (not extern)
+ { }* ;; Reference to the global variable
+ }
+</pre>
+
+<p>These descriptors provide debug information about globals variables. The
+provide details such as name, type and where the variable is defined.</p>
+
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_subprograms">Subprogram descriptors</a>
+</div>
+
+<div class="doc_text">
<pre>
-$ <b>llvm-db funccall</b>
-llvm-db: The LLVM source-level debugger
-Loading program... successfully loaded 'funccall.bc'!
-(llvm-db) <b>create</b>
-Starting program: funccall.bc
-main at funccall.c:9:2
-9 -> q = 0;
-(llvm-db) <b>list main</b>
-4 void foo() {
-5 int t = q;
-6 q = t + 1;
-7 }
-8 int main() {
-9 -> q = 0;
-10 foo();
-11 q = q - 1;
-12
-13 return q;
-(llvm-db) <b>list</b>
-14 }
-(llvm-db) <b>step</b>
-10 -> foo();
-(llvm-db) <b>s</b>
-foo at funccall.c:5:2
-5 -> int t = q;
-(llvm-db) <b>bt</b>
-#0 -> 0x85ffba0 in foo at funccall.c:5:2
-#1 0x85ffd98 in main at funccall.c:10:2
-(llvm-db) <b>finish</b>
-main at funccall.c:11:2
-11 -> q = q - 1;
-(llvm-db) <b>s</b>
-13 -> return q;
-(llvm-db) <b>s</b>
-The program stopped with exit code 0
-(llvm-db) <b>quit</b>
-$
+ %<a href="#format_subprograms">llvm.dbg.subprogram.type</a> = type {
+ uint, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subprogram)
+ { }*, ;; Subprogram anchor = cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_subprograms">llvm.dbg.subprograms</a> to { }*),
+ { }*, ;; Reference to context descriptor
+ sbyte*, ;; Name
+ sbyte*, ;; Display name (fully qualified C++ name)
+ sbyte*, ;; MIPS linkage name (for C++)
+ { }*, ;; Reference to compile unit where defined
+ uint, ;; Line number where defined
+ { }*, ;; Reference to type descriptor
+ bool, ;; True if the global is local to compile unit (static)
+ bool ;; True if the global is defined in the compile unit (not extern)
+ }
</pre>
+<p>These descriptors provide debug information about functions, methods and
+subprograms. They provide details such as name, return types and the source
+location where the subprogram is defined.</p>
+
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_blocks">Block descriptors</a>
+</div>
+
+<div class="doc_text">
+
+<pre>
+ %<a href="#format_blocks">llvm.dbg.block</a> = type {
+ uint, ;; Tag = 13 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
+ { }* ;; Reference to context descriptor
+ }
+</pre>
+<p>These descriptors provide debug information about nested blocks within a
+subprogram. The array of member descriptors is used to define local variables
+and deeper nested blocks.</p>
+</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="startup">Starting the debugger</a>
+<div class="doc_subsubsection">
+ <a name="format_basic_type">Basic type descriptors</a>
</div>
<div class="doc_text">
-<p>There are three ways to start up the <tt>llvm-db</tt> debugger:</p>
+<pre>
+ %<a href="#format_basic_type">llvm.dbg.basictype.type</a> = type {
+ uint, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_base_type)
+ { }*, ;; Reference to context (typically a compile unit)
+ sbyte*, ;; Name (may be "" for anonymous types)
+ { }*, ;; Reference to compile unit where defined (may be NULL)
+ uint, ;; Line number where defined (may be 0)
+ uint, ;; Size in bits
+ uint, ;; Alignment in bits
+ uint, ;; Offset in bits
+ uint ;; Dwarf type encoding
+ }
+</pre>
-<p>When run with no options, just <tt>llvm-db</tt>, the debugger starts up
-without a program loaded at all. You must use the <a
-href="#c_file"><tt>file</tt> command</a> to load a program, and the <a
-href="c_set_args"><tt>set args</tt></a> or <a href="#c_run"><tt>run</tt></a>
-commands to specify the arguments for the program.</p>
+<p>These descriptors define primitive types used in the code. Example int, bool
+and float. The context provides the scope of the type, which is usually the top
+level. Since basic types are not usually user defined the compile unit and line
+number can be left as NULL and 0. The size, alignment and offset are expressed
+in bits and can be 64 bit values. The alignment is used to round the offset
+when embedded in a <a href="#format_composite_type">composite type</a>
+(example to keep float doubles on 64 bit boundaries.) The offset is the bit
+offset if embedded in a <a href="#format_composite_type">composite
+type</a>.</p>
-<p>If you start the debugger with one argument, as <tt>llvm-db
-<program></tt>, the debugger will start up and load in the specified
-program. You can then optionally specify arguments to the program with the <a
-href="c_set_args"><tt>set args</tt></a> or <a href="#c_run"><tt>run</tt></a>
-commands.</p>
+<p>The type encoding provides the details of the type. The values are typically
+one of the following;</p>
-<p>The third way to start the program is with the <tt>--args</tt> option. This
-option allows you to specify the program to load and the arguments to start out
-with. <!-- No options to <tt>llvm-db</tt> may be specified after the
-<tt>-args</tt> option. --> Example use: <tt>llvm-db --args ls /home</tt></p>
+<pre>
+ DW_ATE_address = 1
+ DW_ATE_boolean = 2
+ DW_ATE_float = 4
+ DW_ATE_signed = 5
+ DW_ATE_signed_char = 6
+ DW_ATE_unsigned = 7
+ DW_ATE_unsigned_char = 8
+</pre>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="commands">Commands recognized by the debugger</a>
+<div class="doc_subsubsection">
+ <a name="format_derived_type">Derived type descriptors</a>
</div>
<div class="doc_text">
-<p>FIXME: this needs work obviously. See the <a
-href="http://sources.redhat.com/gdb/documentation/">GDB documentation</a> for
-information about what these do, or try '<tt>help [command]</tt>' within
-<tt>llvm-db</tt> to get information.</p>
+<pre>
+ %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> = type {
+ uint, ;; Tag (see below)
+ { }*, ;; Reference to context
+ sbyte*, ;; Name (may be "" for anonymous types)
+ { }*, ;; Reference to compile unit where defined (may be NULL)
+ uint, ;; Line number where defined (may be 0)
+ uint, ;; Size in bits
+ uint, ;; Alignment in bits
+ uint, ;; Offset in bits
+ { }* ;; Reference to type derived from
+ }
+</pre>
-<p>
-<h2>General usage:</h2>
-<ul>
-<li>help [command]</li>
-<li>quit</li>
-<li><a name="c_file">file</a> [program]</li>
-</ul>
+<p>These descriptors are used to define types derived from other types. The
+value of the tag varies depending on the meaning. The following are possible
+tag values;</p>
-<h2>Program inspection and interaction:</h2>
-<ul>
-<li>create (start the program, stopping it ASAP in <tt>main</tt>)</li>
-<li>kill</li>
-<li>run [args]</li>
-<li>step [num]</li>
-<li>next [num]</li>
-<li>cont</li>
-<li>finish</li>
-
-<li>list [start[, end]]</li>
-<li>info source</li>
-<li>info sources</li>
-<li>info functions</li>
-</ul>
+<pre>
+ DW_TAG_formal_parameter = 5
+ DW_TAG_member = 13
+ DW_TAG_pointer_type = 15
+ DW_TAG_reference_type = 16
+ DW_TAG_typedef = 22
+ DW_TAG_const_type = 38
+ DW_TAG_volatile_type = 53
+ DW_TAG_restrict_type = 55
+</pre>
-<h2>Call stack inspection:</h2>
-<ul>
-<li>backtrace</li>
-<li>up [n]</li>
-<li>down [n]</li>
-<li>frame [n]</li>
-</ul>
+<p> <tt>DW_TAG_member</tt> is used to define a member of a <a
+href="#format_composite_type">composite type</a> or <a
+href="#format_subprograms">subprogram</a>. The type of the member is the <a
+href="#format_derived_type">derived type</a>. <tt>DW_TAG_formal_parameter</tt>
+is used to define a member which is a formal argument of a subprogram.</p>
+<p><tt>DW_TAG_typedef</tt> is used to
+provide a name for the derived type.</p>
-<h2>Debugger inspection and interaction:</h2>
-<ul>
-<li>info target</li>
-<li>show prompt</li>
-<li>set prompt</li>
-<li>show listsize</li>
-<li>set listsize</li>
-<li>show language</li>
-<li>set language</li>
-<li>show args</li>
-<li>set args [args]</li>
-</ul>
+<p><tt>DW_TAG_pointer_type</tt>,
+<tt>DW_TAG_reference_type</tt>, <tt>DW_TAG_const_type</tt>,
+<tt>DW_TAG_volatile_type</tt> and <tt>DW_TAG_restrict_type</tt> are used to
+qualify the <a href="#format_derived_type">derived type</a>. </p>
-<h2>TODO:</h2>
-<ul>
-<li>info frame</li>
-<li>break</li>
-<li>print</li>
-<li>ptype</li>
-
-<li>info types</li>
-<li>info variables</li>
-<li>info program</li>
-
-<li>info args</li>
-<li>info locals</li>
-<li>info catch</li>
-<li>... many others</li>
-</ul>
+<p><a href="#format_derived_type">Derived type</a> location can be determined
+from the compile unit and line number. The size, alignment and offset are
+expressed in bits and can be 64 bit values. The alignment is used to round the
+offset when embedded in a <a href="#format_composite_type">composite type</a>
+(example to keep float doubles on 64 bit boundaries.) The offset is the bit
+offset if embedded in a <a href="#format_composite_type">composite
+type</a>.</p>
+
+<p>Note that the <tt>void *</tt> type is expressed as a
+<tt>llvm.dbg.derivedtype.type</tt> with tag of <tt>DW_TAG_pointer_type</tt> and
+NULL derived type.</p>
</div>
-<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="architecture">Architecture of the LLVM debugger</a>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_composite_type">Composite type descriptors</a>
</div>
-<!-- *********************************************************************** -->
<div class="doc_text">
-<p>The LLVM debugger is built out of three distinct layers of software. These
-layers provide clients with different interface options depending on what pieces
-of they want to implement themselves, and it also promotes code modularity and
-good design. The three layers are the <a href="#arch_debugger">Debugger
-interface</a>, the <a href="#arch_info">"info" interfaces</a>, and the <a
-href="#arch_llvm-db"><tt>llvm-db</tt> tool</a> itself.</p>
+
+<pre>
+ %<a href="#format_composite_type">llvm.dbg.compositetype.type</a> = type {
+ uint, ;; Tag (see below)
+ { }*, ;; Reference to context
+ sbyte*, ;; Name (may be "" for anonymous types)
+ { }*, ;; Reference to compile unit where defined (may be NULL)
+ uint, ;; Line number where defined (may be 0)
+ uint, ;; Size in bits
+ uint, ;; Alignment in bits
+ uint, ;; Offset in bits
+ { }* ;; Reference to array of member descriptors
+ }
+</pre>
+
+<p>These descriptors are used to define types that are composed of 0 or more
+elements. The value of the tag varies depending on the meaning. The following
+are possible tag values;</p>
+
+<pre>
+ DW_TAG_array_type = 1
+ DW_TAG_enumeration_type = 4
+ DW_TAG_structure_type = 19
+ DW_TAG_union_type = 23
+ DW_TAG_vector_type = 259
+ DW_TAG_subroutine_type = 46
+ DW_TAG_inheritance = 26
+</pre>
+
+<p>The vector flag indicates that an array type is a native packed vector.</p>
+
+<p>The members of array types (tag = <tt>DW_TAG_array_type</tt>) or vector types
+(tag = <tt>DW_TAG_vector_type</tt>) are <a href="#format_subrange">subrange
+descriptors</a>, each representing the range of subscripts at that level of
+indexing.</p>
+
+<p>The members of enumeration types (tag = <tt>DW_TAG_enumeration_type</tt>) are
+<a href="#format_enumeration">enumerator descriptors</a>, each representing the
+definition of enumeration value
+for the set.</p>
+
+<p>The members of structure (tag = <tt>DW_TAG_structure_type</tt>) or union (tag
+= <tt>DW_TAG_union_type</tt>) types are any one of the <a
+href="#format_basic_type">basic</a>, <a href="#format_derived_type">derived</a>
+or <a href="#format_composite_type">composite</a> type descriptors, each
+representing a field member of the structure or union.</p>
+
+<p>For C++ classes (tag = <tt>DW_TAG_structure_type</tt>), member descriptors
+provide information about base classes, static members and member functions. If
+a member is a <a href="#format_derived_type">derived type descriptor</a> and has
+a tag of <tt>DW_TAG_inheritance</tt>, then the type represents a base class. If
+the member of is a <a href="#format_global_variables">global variable
+descriptor</a> then it represents a static member. And, if the member is a <a
+href="#format_subprograms">subprogram descriptor</a> then it represents a member
+function. For static members and member functions, <tt>getName()</tt> returns
+the members link or the C++ mangled name. <tt>getDisplayName()</tt> the
+simplied version of the name.</p>
+
+<p>The first member of subroutine (tag = <tt>DW_TAG_subroutine_type</tt>)
+type elements is the return type for the subroutine. The remaining
+elements are the formal arguments to the subroutine.</p>
+
+<p><a href="#format_composite_type">Composite type</a> location can be
+determined from the compile unit and line number. The size, alignment and
+offset are expressed in bits and can be 64 bit values. The alignment is used to
+round the offset when embedded in a <a href="#format_composite_type">composite
+type</a> (as an example, to keep float doubles on 64 bit boundaries.) The offset
+is the bit offset if embedded in a <a href="#format_composite_type">composite
+type</a>.</p>
+
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="arch_debugger">The Debugger and InferiorProcess classes</a>
+<div class="doc_subsubsection">
+ <a name="format_subrange">Subrange descriptors</a>
</div>
<div class="doc_text">
-<p>The Debugger class (defined in the <tt>include/llvm/Debugger/</tt> directory)
-is a low-level class which is used to maintain information about the loaded
-program, as well as start and stop the program running as necessary. This class
-does not provide any high-level analysis or control over the program, only
-exposing simple interfaces like <tt>load/unloadProgram</tt>,
-<tt>create/killProgram</tt>, <tt>step/next/finish/contProgram</tt>, and
-low-level methods for installing breakpoints.</p>
-
-<p>
-The Debugger class is itself a wrapper around the lowest-level InferiorProcess
-class. This class is used to represent an instance of the program running under
-debugger control. The InferiorProcess class can be implemented in different
-ways for different targets and execution scenarios (e.g., remote debugging).
-The InferiorProcess class exposes a small and simple collection of interfaces
-which are useful for inspecting the current state of the program (such as
-collecting stack trace information, reading the memory image of the process,
-etc). The interfaces in this class are designed to be as low-level and simple
-as possible, to make it easy to create new instances of the class.
-</p>
-
-<p>
-The Debugger class exposes the currently active instance of InferiorProcess
-through the <tt>Debugger::getRunningProcess</tt> method, which returns a
-<tt>const</tt> reference to the class. This means that clients of the Debugger
-class can only <b>inspect</b> the running instance of the program directly. To
-change the executing process in some way, they must use the interces exposed by
-the Debugger class.
-</p>
+
+<pre>
+ %<a href="#format_subrange">llvm.dbg.subrange.type</a> = type {
+ uint, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
+ uint, ;; Low value
+ uint ;; High value
+ }
+</pre>
+
+<p>These descriptors are used to define ranges of array subscripts for an array
+<a href="#format_composite_type">composite type</a>. The low value defines the
+lower bounds typically zero for C/C++. The high value is the upper bounds.
+Values are 64 bit. High - low + 1 is the size of the array. If
+low == high the array will be unbounded.</p>
+
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="arch_info">The RuntimeInfo, ProgramInfo, and SourceLanguage classes</a>
+<div class="doc_subsubsection">
+ <a name="format_enumeration">Enumerator descriptors</a>
</div>
<div class="doc_text">
-<p>
-The next-highest level of debugger abstraction is provided through the
-ProgramInfo, RuntimeInfo, SourceLanguage and related classes (also defined in
-the <tt>include/llvm/Debugger/</tt> directory). These classes efficiently
-decode the debugging information and low-level interfaces exposed by
-InferiorProcess into a higher-level representation, suitable for analysis by the
-debugger.
-</p>
-
-<p>
-The ProgramInfo class exposes a variety of different kinds of information about
-the program objects in the source-level-language. The SourceFileInfo class
-represents a source-file in the program (e.g. a .cpp or .h file). The
-SourceFileInfo class captures information such as which SourceLanguage was used
-to compile the file, where the debugger can get access to the actual file text
-(which is lazily loaded on demand), etc. The SourceFunctionInfo class
-represents a... <b>FIXME: finish</b>. The ProgramInfo class provides interfaces
-to lazily find and decode the information needed to create the Source*Info
-classes requested by the debugger.
-</p>
-
-<p>
-The RuntimeInfo class exposes information about the currently executed program,
-by decoding information from the InferiorProcess and ProgramInfo classes. It
-provides a StackFrame class which provides an easy-to-use interface for
-inspecting the current and suspended stack frames in the program.
-</p>
-
-<p>
-The SourceLanguage class is an abstract interface used by the debugger to
-perform all source-language-specific tasks. For example, this interface is used
-by the ProgramInfo class to decode language-specific types and functions and by
-the debugger front-end (such as <a href="#arch_llvm-db"><tt>llvm-db</tt></a> to
-evaluate source-langauge expressions typed into the debugger. This class uses
-the RuntimeInfo & ProgramInfo classes to get information about the current
-execution context and the loaded program, respectively.
-</p>
+
+<pre>
+ %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> = type {
+ uint, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_enumerator)
+ sbyte*, ;; Name
+ uint ;; Value
+ }
+</pre>
+
+<p>These descriptors are used to define members of an enumeration <a
+href="#format_composite_type">composite type</a>, it associates the name to the
+value.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="arch_llvm-db">The <tt>llvm-db</tt> tool</a>
+<div class="doc_subsubsection">
+ <a name="format_variables">Local variables</a>
</div>
<div class="doc_text">
-<p>
-The <tt>llvm-db</tt> is designed to be a debugger providing an interface as <a
-href="#llvm-db">similar to GDB</a> as reasonable, but no more so than that.
-Because the <a href="#arch_debugger">Debugger</a> and <a
-href="#arch_info">info</a> classes implement all of the heavy lifting and
-analysis, <tt>llvm-db</tt> (which lives in <tt>llvm/tools/llvm-db</tt>) consists
-mainly of of code to interact with the user and parse commands. The CLIDebugger
-constructor registers all of the builtin commands for the debugger, and each
-command is implemented as a CLIDebugger::[name]Command method.
-</p>
-</div>
+<pre>
+ %<a href="#format_variables">llvm.dbg.variable.type</a> = type {
+ uint, ;; Tag (see below)
+ { }*, ;; Context
+ sbyte*, ;; Name
+ { }*, ;; Reference to compile unit where defined
+ uint, ;; Line number where defined
+ { }* ;; Type descriptor
+ }
+</pre>
+
+<p>These descriptors are used to define variables local to a sub program. The
+value of the tag depends on the usage of the variable;</p>
+
+<pre>
+ DW_TAG_auto_variable = 256
+ DW_TAG_arg_variable = 257
+ DW_TAG_return_variable = 258
+</pre>
+
+<p>An auto variable is any variable declared in the body of the function. An
+argument variable is any variable that appears as a formal argument to the
+function. A return variable is used to track the result of a function and has
+no source correspondent.</p>
+<p>The context is either the subprogram or block where the variable is defined.
+Name the source variable name. Compile unit and line indicate where the
+variable was defined. Type descriptor defines the declared type of the
+variable.</p>
+
+</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="arch_todo">Short-term TODO list</a>
+ <a name="format_common_intrinsics">Debugger intrinsic functions</a>
</div>
<div class="doc_text">
-<p>
-FIXME: this section will eventually go away. These are notes to myself of
-things that should be implemented, but haven't yet.
-</p>
-
-<p>
-<b>Breakpoints:</b> Support is already implemented in the 'InferiorProcess'
-class, though it hasn't been tested yet. To finish breakpoint support, we need
-to implement breakCommand (which should reuse the linespec parser from the list
-command), and handle the fact that 'break foo' or 'break file.c:53' may insert
-multiple breakpoints. Also, if you say 'break file.c:53' and there is no
-stoppoint on line 53, the breakpoint should go on the next available line. My
-idea was to have the Debugger class provide a "Breakpoint" class which
-encapsulated this messiness, giving the debugger front-end a simple interface.
-The debugger front-end would have to map the really complex semantics of
-temporary breakpoints and 'conditional' breakpoints onto this intermediate
-level. Also, breakpoints should survive as much as possible across program
-reloads.
-</p>
-
-<p>
-<b>UnixLocalInferiorProcess.cpp speedup</b>: There is no reason for the debugged
-process to code gen the globals corresponding to debug information. The
-IntrinsicLowering object could instead change descriptors into constant expr
-casts of the constant address of the LLVM objects for the descriptors. This
-would also allow us to eliminate the mapping back and forth between physical
-addresses that must be done.</p>
-
-<p>
-<b>Process deaths</b>: The InferiorProcessDead exception should be extended to
-know "how" a process died, i.e., it was killed by a signal. This is easy to
-collect in the UnixLocalInferiorProcess, we just need to represent it.</p>
+<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
+provide debug information at various points in generated code.</p>
</div>
-<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="format">Debugging information format</a>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_common_stoppoint">llvm.dbg.stoppoint</a>
</div>
-<!-- *********************************************************************** -->
<div class="doc_text">
+<pre>
+ void %<a href="#format_common_stoppoint">llvm.dbg.stoppoint</a>( uint, uint, { }* )
+</pre>
-<p>LLVM debugging information has been carefully designed to make it possible
-for the optimizer to optimize the program and debugging information without
-necessarily having to know anything about debugging information. In particular,
-the global constant merging pass automatically eliminates duplicated debugging
-information (often caused by header files), the global dead code elimination
-pass automatically deletes debugging information for a function if it decides to
-delete the function, and the linker eliminates debug information when it merges
-<tt>linkonce</tt> functions.</p>
+<p>This intrinsic is used to provide correspondence between the source file and
+the generated code. The first argument is the line number (base 1), second
+argument is the column number (0 if unknown) and the third argument the source
+<tt>%<a href="#format_compile_units">llvm.dbg.compile_unit</a>*</tt> cast to a
+<tt>{ }*</tt>. Code following a call to this intrinsic will have been defined
+in close proximity of the line, column and file. This information holds until
+the next call to <tt>%<a
+href="#format_common_stoppoint">lvm.dbg.stoppoint</a></tt>.</p>
-<p>To do this, most of the debugging information (descriptors for types,
-variables, functions, source files, etc) is inserted by the language front-end
-in the form of LLVM global variables. These LLVM global variables are no
-different from any other global variables, except that they have a web of LLVM
-intrinsic functions that point to them. If the last references to a particular
-piece of debugging information are deleted (for example, by the
-<tt>-globaldce</tt> pass), the extraneous debug information will automatically
-become dead and be removed by the optimizer.</p>
+</div>
-<p>The debugger is designed to be agnostic about the contents of most of the
-debugging information. It uses a <a href="#arch_info">source-language-specific
-module</a> to decode the information that represents variables, types,
-functions, namespaces, etc: this allows for arbitrary source-language semantics
-and type-systems to be used, as long as there is a module written for the
-debugger to interpret the information.</p>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_common_func_start">llvm.dbg.func.start</a>
+</div>
-<p>To provide basic functionality, the LLVM debugger does have to make some
-assumptions about the source-level language being debugged, though it keeps
-these to a minimum. The only common features that the LLVM debugger assumes
-exist are <a href="#format_common_source_files">source files</a>, and <a
-href="#format_program_objects">program objects</a>. These abstract objects are
-used by the debugger to form stack traces, show information about local
-variables, etc.</p>
+<div class="doc_text">
+<pre>
+ void %<a href="#format_common_func_start">llvm.dbg.func.start</a>( { }* )
+</pre>
-<p>This section of the documentation first describes the representation aspects
-common to any source-language. The <a href="#ccxx_frontend">next section</a>
-describes the data layout conventions used by the C and C++ front-ends.</p>
+<p>This intrinsic is used to link the debug information in <tt>%<a
+href="#format_subprograms">llvm.dbg.subprogram</a></tt> to the function. It also
+defines the beginning of the function's declarative region (scope.) The
+intrinsic should be called early in the function after the all the alloca
+instructions. It should be paired off with a closing <tt>%<a
+href="#format_common_region_end">llvm.dbg.region.end</a></tt>. The function's
+single argument is the <tt>%<a
+href="#format_subprograms">llvm.dbg.subprogram.type</a></tt>.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="format_common_anchors">Anchors for global objects</a>
+<div class="doc_subsubsection">
+ <a name="format_common_region_start">llvm.dbg.region.start</a>
</div>
<div class="doc_text">
-<p>One important aspect of the LLVM debug representation is that it allows the
-LLVM debugger to efficiently index all of the global objects without having the
-scan the program. To do this, all of the global objects use "anchor" globals of
-type "<tt>{}</tt>", with designated names. These anchor objects obviously do
-not contain any content or meaning by themselves, but all of the global objects
-of a particular type (e.g., source file descriptors) contain a pointer to the
-anchor. This pointer allows the debugger to use def-use chains to find all
-global objects of that type.</p>
+<pre>
+ void %<a href="#format_common_region_start">llvm.dbg.region.start</a>( { }* )
+</pre>
+
+<p>This intrinsic is used to define the beginning of a declarative scope (ex.
+block) for local language elements. It should be paired off with a closing
+<tt>%<a href="#format_common_region_end">llvm.dbg.region.end</a></tt>. The
+function's single argument is the <tt>%<a
+href="#format_blocks">llvm.dbg.block</a></tt> which is starting.</p>
+
+
+</div>
-<p>So far, the following names are recognized as anchors by the LLVM
-debugger:</p>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_common_region_end">llvm.dbg.region.end</a>
+</div>
+<div class="doc_text">
<pre>
- %<a href="#format_common_source_files">llvm.dbg.translation_units</a> = linkonce global {} {}
- %<a href="#format_program_objects">llvm.dbg.globals</a> = linkonce global {} {}
+ void %<a href="#format_common_region_end">llvm.dbg.region.end</a>( { }* )
</pre>
-<p>Using anchors in this way (where the source file descriptor points to the
-anchors, as opposed to having a list of source file descriptors) allows for the
-standard dead global elimination and merging passes to automatically remove
-unused debugging information. If the globals were kept track of through lists,
-there would always be an object pointing to the descriptors, thus would never be
-deleted.</p>
+<p>This intrinsic is used to define the end of a declarative scope (ex. block)
+for local language elements. It should be paired off with an opening <tt>%<a
+href="#format_common_region_start">llvm.dbg.region.start</a></tt> or <tt>%<a
+href="#format_common_func_start">llvm.dbg.func.start</a></tt>. The function's
+single argument is either the <tt>%<a
+href="#format_blocks">llvm.dbg.block</a></tt> or the <tt>%<a
+href="#format_subprograms">llvm.dbg.subprogram.type</a></tt> which is
+ending.</p>
+
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_common_declare">llvm.dbg.declare</a>
+</div>
+
+<div class="doc_text">
+<pre>
+ void %<a href="#format_common_declare">llvm.dbg.declare</a>( { } *, { }* )
+</pre>
+
+<p>This intrinsic provides information about a local element (ex. variable.) The
+first argument is the alloca for the variable, cast to a <tt>{ }*</tt>. The
+second argument is the <tt>%<a
+href="#format_variables">llvm.dbg.variable</a></tt> containing the description
+of the variable, also cast to a <tt>{ }*</tt>.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="format_common_stoppoint">
+ <a name="format_common_stoppoints">
Representing stopping points in the source program
</a>
</div>
<p>LLVM debugger "stop points" are a key part of the debugging representation
that allows the LLVM to maintain simple semantics for <a
href="#debugopt">debugging optimized code</a>. The basic idea is that the
-front-end inserts calls to the <tt>%llvm.dbg.stoppoint</tt> intrinsic function
-at every point in the program where the debugger should be able to inspect the
-program (these correspond to places the debugger stops when you "<tt>step</tt>"
-through it). The front-end can choose to place these as fine-grained as it
-would like (for example, before every subexpression evaluated), but it is
-recommended to only put them after every source statement that includes
-executable code.</p>
+front-end inserts calls to the <a
+href="#format_common_stoppoint">%<tt>llvm.dbg.stoppoint</tt></a> intrinsic
+function at every point in the program where a debugger should be able to
+inspect the program (these correspond to places a debugger stops when you
+"<tt>step</tt>" through it). The front-end can choose to place these as
+fine-grained as it would like (for example, before every subexpression
+evaluated), but it is recommended to only put them after every source statement
+that includes executable code.</p>
<p>Using calls to this intrinsic function to demark legal points for the
debugger to inspect the program automatically disables any optimizations that
optimization of subexpressions, code duplication transformations, or basic-block
reordering transformations.</p>
-<p>An important aspect of the calls to the <tt>%llvm.dbg.stoppoint</tt>
-intrinsic is that the function-local debugging information is woven together
-with use-def chains. This makes it easy for the debugger to, for example,
-locate the 'next' stop point. For a concrete example of stop points, see the
-example in <a href="#format_common_lifetime">the next section</a>.</p>
-
</div>
9. }
</pre>
-<p>Compiled to LLVM, this function would be represented like this (FIXME: CHECK
-AND UPDATE THIS):</p>
+<p>Compiled to LLVM, this function would be represented like this:</p>
<pre>
void %foo() {
+entry:
%X = alloca int
%Y = alloca int
%Z = alloca int
- <a name="#icl_ex_D1">%D1</a> = call {}* %llvm.dbg.func.start(<a href="#format_program_objects">%lldb.global</a>* %d.foo)
- %D2 = call {}* <a href="#format_common_stoppoint">%llvm.dbg.stoppoint</a>({}* %D1, uint 2, uint 2, <a href="#format_common_source_files">%lldb.compile_unit</a>* %file)
-
- %D3 = call {}* %llvm.dbg.DEFINEVARIABLE({}* %D2, ...)
+
+ ...
+
+ 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 )
+
+ 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 )
+
+ call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %X, ...)
+ call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %Y, ...)
+
<i>;; Evaluate expression on line 2, assigning to X.</i>
- %D4 = call {}* <a href="#format_common_stoppoint">%llvm.dbg.stoppoint</a>({}* %D3, uint 3, uint 2, <a href="#format_common_source_files">%lldb.compile_unit</a>* %file)
-
- %D5 = call {}* %llvm.dbg.DEFINEVARIABLE({}* %D4, ...)
+
+ 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 )
+
<i>;; Evaluate expression on line 3, assigning to Y.</i>
- %D6 = call {}* <a href="#format_common_stoppoint">%llvm.dbg.stoppoint</a>({}* %D5, uint 5, uint 4, <a href="#format_common_source_files">%lldb.compile_unit</a>* %file)
-
- <a name="#icl_ex_D1">%D7</a> = call {}* %llvm.region.start({}* %D6)
- %D8 = call {}* %llvm.dbg.DEFINEVARIABLE({}* %D7, ...)
+
+ call void %<a href="#format_common_stoppoint">llvm.region.start</a>()
+ 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 )
+ call void %<a href="#format_common_declare">llvm.dbg.declare</a>({}* %X, ...)
+
<i>;; Evaluate expression on line 5, assigning to Z.</i>
- %D9 = call {}* <a href="#format_common_stoppoint">%llvm.dbg.stoppoint</a>({}* %D8, uint 6, uint 4, <a href="#format_common_source_files">%lldb.compile_unit</a>* %file)
-
- <i>;; Code for line 6.</i>
- %D10 = call {}* %llvm.region.end({}* %D9)
- %D11 = call {}* <a href="#format_common_stoppoint">%llvm.dbg.stoppoint</a>({}* %D10, uint 8, uint 2, <a href="#format_common_source_files">%lldb.compile_unit</a>* %file)
-
- <i>;; Code for line 8.</i>
- <a name="#icl_ex_D1">%D12</a> = call {}* %llvm.region.end({}* %D11)
+
+ 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 )
+ call void %<a href="#format_common_region_end">llvm.region.end</a>()
+
+ 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 )
+
+ call void %<a href="#format_common_region_end">llvm.region.end</a>()
+
ret void
}
</pre>
<p>This example illustrates a few important details about the LLVM debugging
-information. In particular, it shows how the various intrinsics used are woven
-together with def-use and use-def chains, similar to how <a
-href="#format_common_anchors">anchors</a> are used with globals. This allows
-the debugger to analyze the relationship between statements, variable
-definitions, and the code used to implement the function.</p>
-
-<p>In this example, two explicit regions are defined, one with the <a
-href="#icl_ex_D1">definition of the <tt>%D1</tt> variable</a> and one with the
-<a href="#icl_ex_D7">definition of <tt>%D7</tt></a>. In the case of
-<tt>%D1</tt>, the debug information indicates that the function whose <a
-href="#format_program_objects">descriptor</a> is specified as an argument to the
-intrinsic. This defines a new stack frame whose lifetime ends when the region
-is ended by <a href="#icl_ex_D12">the <tt>%D12</tt> call</a>.</p>
+information. In particular, it shows how the various intrinsics are applied
+together to allow a debugger to analyze the relationship between statements,
+variable definitions, and the code used to implement the function.</p>
+
+<p>The first intrinsic <tt>%<a
+href="#format_common_func_start">llvm.dbg.func.start</a></tt> provides
+a link with the <a href="#format_subprograms">subprogram descriptor</a>
+containing the details of this function. This call also defines the beginning
+of the function region, bounded by the <tt>%<a
+href="#format_common_region_end">llvm.region.end</a></tt> at the end of
+the function. This region is used to bracket the lifetime of variables declared
+within. For a function, this outer region defines a new stack frame whose
+lifetime ends when the region is ended.</p>
+
+<p>It is possible to define inner regions for short term variables by using the
+%<a href="#format_common_stoppoint"><tt>llvm.region.start</tt></a> and <a
+href="#format_common_region_end"><tt>%llvm.region.end</tt></a> to bound a
+region. The inner region in this example would be for the block containing the
+declaration of Z.</p>
<p>Using regions to represent the boundaries of source-level functions allow
LLVM interprocedural optimizations to arbitrarily modify LLVM functions without
drawn between LLVM functions and their source-level counterparts (note however,
that if the inliner inlines all instances of a non-strong-linkage function into
its caller that it will not be possible for the user to manually invoke the
-inlined function from the debugger).</p>
+inlined function from a debugger).</p>
<p>Once the function has been defined, the <a
-href="#format_common_stoppoint">stopping point</a> corresponding to line #2 of
-the function is encountered. At this point in the function, <b>no</b> local
-variables are live. As lines 2 and 3 of the example are executed, their
-variable definitions are automatically introduced into the program, without the
+href="#format_common_stoppoint"><tt>stopping point</tt></a> corresponding to
+line #2 (column #2) of the function is encountered. At this point in the
+function, <b>no</b> local variables are live. As lines 2 and 3 of the example
+are executed, their variable definitions are introduced into the program using
+%<a href="#format_common_declare"><tt>llvm.dbg.declare</tt></a>, without the
need to specify a new region. These variables do not require new regions to be
introduced because they go out of scope at the same point in the program: line
9.</p>
<p>In contrast, the <tt>Z</tt> variable goes out of scope at a different time,
-on line 7. For this reason, it is defined within <a href="#icl_ex_D7">the
-<tt>%D7</tt> region</a>, which kills the availability of <tt>Z</tt> before the
-code for line 8 is executed. In this way, regions can support arbitrary
-source-language scoping rules, as long as they can only be nested (ie, one scope
-cannot partially overlap with a part of another scope).</p>
+on line 7. For this reason, it is defined within the inner region, which kills
+the availability of <tt>Z</tt> before the code for line 8 is executed. In this
+way, regions can support arbitrary source-language scoping rules, as long as
+they can only be nested (ie, one scope cannot partially overlap with a part of
+another scope).</p>
<p>It is worth noting that this scoping mechanism is used to control scoping of
all declarations, not just variable declarations. For example, the scope of a
-C++ using declaration is controlled with this, and the <tt>llvm-db</tt> C++
-support routines could use this to change how name lookup is performed (though
-this is not implemented yet).</p>
+C++ using declaration is controlled with this and could change how name lookup is
+performed.</p>
+
+</div>
+
+
+
+<!-- *********************************************************************** -->
+<div class="doc_section">
+ <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
+</div>
+<!-- *********************************************************************** -->
+
+<div class="doc_text">
+
+<p>The C and C++ front-ends represent information about the program in a format
+that is effectively identical to <a
+href="http://www.eagercon.com/dwarf/dwarf3std.htm">Dwarf 3.0</a> in terms of
+information content. This allows code generators to trivially support native
+debuggers by generating standard dwarf information, and contains enough
+information for non-dwarf targets to translate it as needed.</p>
+
+<p>This section describes the forms used to represent C and C++ programs. Other
+languages could pattern themselves after this (which itself is tuned to
+representing programs in the same way that Dwarf 3 does), or they could choose
+to provide completely different forms if they don't fit into the Dwarf model.
+As support for debugging information gets added to the various LLVM
+source-language front-ends, the information used should be documented here.</p>
+
+<p>The following sections provide examples of various C/C++ constructs and the
+debug information that would best describe those constructs.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="format_common_descriptors">Object descriptor formats</a>
+ <a name="ccxx_compile_units">C/C++ source file information</a>
</div>
<div class="doc_text">
-<p>The LLVM debugger expects the descriptors for program objects to start in a
-canonical format, but the descriptors can include additional information
-appended at the end that is source-language specific. All LLVM debugging
-information is versioned, allowing backwards compatibility in the case that the
-core structures need to change in some way. Also, all debugging information
-objects start with a <a href="#format_common_tags">tag</a> to indicate what type
-of object it is. The source-language is allows to define its own objects, by
-using unreserved tag numbers.</p>
-<p>The lowest-level descriptor are those describing <a
-href="#format_common_source_files">the files containing the program source
-code</a>, as most other descriptors (sometimes indirectly) refer to them.
-</p>
+<p>Given the source files "MySource.cpp" and "MyHeader.h" located in the
+directory "/Users/mine/sources", the following code;</p>
+
+<pre>
+#include "MyHeader.h"
+
+int main(int argc, char *argv[]) {
+ return 0;
+}
+</pre>
+
+<p>a C/C++ front-end would generate the following descriptors;</p>
+
+<pre>
+...
+;;
+;; Define types used. In this case we need one for compile unit anchors and one
+;; for compile units.
+;;
+%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
+%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = type { uint, { }*, uint, uint, sbyte*, sbyte*, sbyte* }
+...
+;;
+;; Define the anchor for compile units. Note that the second field of the
+;; anchor is 17, which is the same as the tag for compile units
+;; (17 = DW_TAG_compile_unit.)
+;;
+%<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"
+
+;;
+;; Define the compile unit for the source file "/Users/mine/sources/MySource.cpp".
+;;
+%<a href="#format_compile_units">llvm.dbg.compile_unit1</a> = internal constant %<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> {
+ uint add(uint 17, uint 262144),
+ { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_units</a> to { }*),
+ uint 1,
+ uint 1,
+ sbyte* getelementptr ([13 x sbyte]* %str1, int 0, int 0),
+ sbyte* getelementptr ([21 x sbyte]* %str2, int 0, int 0),
+ sbyte* getelementptr ([33 x sbyte]* %str3, int 0, int 0) }, section "llvm.metadata"
+
+;;
+;; Define the compile unit for the header file "/Users/mine/sources/MyHeader.h".
+;;
+%<a href="#format_compile_units">llvm.dbg.compile_unit2</a> = internal constant %<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> {
+ uint add(uint 17, uint 262144),
+ { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_units</a> to { }*),
+ uint 1,
+ uint 1,
+ sbyte* getelementptr ([11 x sbyte]* %str4, int 0, int 0),
+ sbyte* getelementptr ([21 x sbyte]* %str2, int 0, int 0),
+ sbyte* getelementptr ([33 x sbyte]* %str3, int 0, int 0) }, section "llvm.metadata"
+
+;;
+;; Define each of the strings used in the compile units.
+;;
+%str1 = internal constant [13 x sbyte] c"MySource.cpp\00", section "llvm.metadata";
+%str2 = internal constant [21 x sbyte] c"/Users/mine/sources/\00", section "llvm.metadata";
+%str3 = internal constant [33 x sbyte] c"4.0.1 LLVM (LLVM research group)\00", section "llvm.metadata";
+%str4 = internal constant [11 x sbyte] c"MyHeader.h\00", section "llvm.metadata";
+...
+</pre>
+
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="ccxx_global_variable">C/C++ global variable information</a>
+</div>
+
+<div class="doc_text">
+
+<p>Given an integer global variable declared as follows;</p>
+
+<pre>
+int MyGlobal = 100;
+</pre>
+
+<p>a C/C++ front-end would generate the following descriptors;</p>
+
+<pre>
+;;
+;; Define types used. One for global variable anchors, one for the global
+;; variable descriptor, one for the global's basic type and one for the global's
+;; compile unit.
+;;
+%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
+%<a href="#format_global_variables">llvm.dbg.global_variable.type</a> = type { uint, { }*, { }*, sbyte*, { }*, uint, { }*, bool, bool, { }*, uint }
+%<a href="#format_basic_type">llvm.dbg.basictype.type</a> = type { uint, { }*, sbyte*, { }*, int, uint, uint, uint, uint }
+%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = ...
+...
+;;
+;; Define the global itself.
+;;
+%MyGlobal = global int 100
+...
+;;
+;; Define the anchor for global variables. Note that the second field of the
+;; anchor is 52, which is the same as the tag for global variables
+;; (52 = DW_TAG_variable.)
+;;
+%<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"
+
+;;
+;; Define the global variable descriptor. Note the reference to the global
+;; variable anchor and the global variable itself.
+;;
+%<a href="#format_global_variables">llvm.dbg.global_variable</a> = internal constant %<a href="#format_global_variables">llvm.dbg.global_variable.type</a> {
+ uint add(uint 52, uint 262144),
+ { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_global_variables">llvm.dbg.global_variables</a> to { }*),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([9 x sbyte]* %str1, int 0, int 0),
+ sbyte* getelementptr ([1 x sbyte]* %str2, int 0, int 0),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ uint 1,
+ { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*),
+ bool false,
+ bool true,
+ { }* cast (int* %MyGlobal to { }*) }, section "llvm.metadata"
+
+;;
+;; Define the basic type of 32 bit signed integer. Note that since int is an
+;; intrinsic type the source file is NULL and line 0.
+;;
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([4 x sbyte]* %str3, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 32,
+ uint 32,
+ uint 0,
+ uint 5 }, section "llvm.metadata"
+
+;;
+;; Define the names of the global variable and basic type.
+;;
+%str1 = internal constant [9 x sbyte] c"MyGlobal\00", section "llvm.metadata"
+%str2 = internal constant [1 x sbyte] c"\00", section "llvm.metadata"
+%str3 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
+</pre>
-<!-- ------------------------------------------------------------------------ ->
-<div class="doc_subsubsection">
- <a name="format_common_source_files">Representation of source files</a>
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="ccxx_subprogram">C/C++ function information</a>
</div>
<div class="doc_text">
-<p>
-Source file descriptors are patterned after the Dwarf "compile_unit" object.
-The descriptor currently is defined to have at least the following LLVM
-type entries:</p>
+
+<p>Given a function declared as follows;</p>
<pre>
-%lldb.compile_unit = type {
- uint, <i>;; Tag: <a href="#tag_compile_unit">LLVM_COMPILE_UNIT</a></i>
- ushort, <i>;; LLVM debug version number</i>
- ushort, <i>;; Dwarf language identifier</i>
- sbyte*, <i>;; Filename</i>
- sbyte*, <i>;; Working directory when compiled</i>
- sbyte* <i>;; Producer of the debug information</i>
+int main(int argc, char *argv[]) {
+ return 0;
}
</pre>
-<p>
-These descriptors contain the version number for the debug info, a source
-language ID for the file (we use the Dwarf 3.0 ID numbers, such as
-<tt>DW_LANG_C89</tt>, <tt>DW_LANG_C_plus_plus</tt>, <tt>DW_LANG_Cobol74</tt>,
-etc), three strings describing the filename, working directory of the compiler,
-and an identifier string for the compiler that produced it. Note that actual
-compile_unit declarations must also include an <a
-href="#format_common_anchors">anchor</a> to <tt>llvm.dbg.translation_units</tt>,
-but it is not specified where the anchor is to be located. Here is an example
-descriptor:
-</p>
-
-<p><pre>
-%arraytest_source_file = internal constant %lldb.compile_unit {
- <a href="#tag_compile_unit">uint 17</a>, ; Tag value
- ushort 0, ; Version #0
- ushort 1, ; DW_LANG_C89
- sbyte* getelementptr ([12 x sbyte]* %.str_1, long 0, long 0), ; filename
- sbyte* getelementptr ([12 x sbyte]* %.str_2, long 0, long 0), ; working dir
- sbyte* getelementptr ([12 x sbyte]* %.str_3, long 0, long 0), ; producer
- {}* %llvm.dbg.translation_units ; Anchor
+<p>a C/C++ front-end would generate the following descriptors;</p>
+
+<pre>
+;;
+;; Define types used. One for subprogram anchors, one for the subprogram
+;; descriptor, one for the global's basic type and one for the subprogram's
+;; compile unit.
+;;
+%<a href="#format_subprograms">llvm.dbg.subprogram.type</a> = type { uint, { }*, { }*, sbyte*, { }*, bool, bool }
+%<a href="#format_anchors">llvm.dbg.anchor.type</a> = type { uint, uint }
+%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = ...
+
+;;
+;; Define the anchor for subprograms. Note that the second field of the
+;; anchor is 46, which is the same as the tag for subprograms
+;; (46 = DW_TAG_subprogram.)
+;;
+%<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"
+
+;;
+;; Define the descriptor for the subprogram. TODO - more details.
+;;
+%<a href="#format_subprograms">llvm.dbg.subprogram</a> = internal constant %<a href="#format_subprograms">llvm.dbg.subprogram.type</a> {
+ uint add(uint 46, uint 262144),
+ { }* cast (%<a href="#format_anchors">llvm.dbg.anchor.type</a>* %<a href="#format_subprograms">llvm.dbg.subprograms</a> to { }*),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([5 x sbyte]* %str1, int 0, int 0),
+ sbyte* getelementptr ([1 x sbyte]* %str2, int 0, int 0),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ uint 1,
+ { }* null,
+ bool false,
+ bool true }, section "llvm.metadata"
+
+;;
+;; Define the name of the subprogram.
+;;
+%str1 = internal constant [5 x sbyte] c"main\00", section "llvm.metadata"
+%str2 = internal constant [1 x sbyte] c"\00", section "llvm.metadata"
+
+;;
+;; Define the subprogram itself.
+;;
+int %main(int %argc, sbyte** %argv) {
+...
}
-%.str_1 = internal constant [12 x sbyte] c"arraytest.c\00"
-%.str_2 = internal constant [12 x sbyte] c"/home/sabre\00"
-%.str_3 = internal constant [12 x sbyte] c"llvmgcc 3.4\00"
-</pre></p>
+</pre>
-<p>
-Note that the LLVM constant merging pass should eliminate duplicate copies of
-the strings that get emitted to each translation unit, such as the producer.
-</p>
+</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="ccxx_basic_types">C/C++ basic types</a>
</div>
+<div class="doc_text">
+
+<p>The following are the basic type descriptors for C/C++ core types;</p>
-<!-- ----------------------------------------------------------------------- -->
+</div>
+
+<!-- ======================================================================= -->
<div class="doc_subsubsection">
- <a name="format_program_objects">Representation of program objects</a>
+ <a name="ccxx_basic_type_bool">bool</a>
</div>
<div class="doc_text">
-<p>
-The LLVM debugger needs to know about some source-language program objects, in
-order to build stack traces, print information about local variables, and other
-related activities. The LLVM debugger differentiates between three different
-types of program objects: subprograms (functions, messages, methods, etc),
-variables (locals and globals), and others. Because source-languages have
-widely varying forms of these objects, the LLVM debugger expects only a few
-fields in the descriptor for each object:
-</p>
<pre>
-%lldb.object = type {
- uint, <i>;; <a href="#format_common_tag">A tag</a></i>
- <i>any</i>*, <i>;; The <a href="#format_common_object_contexts">context</a> for the object</i>
- sbyte* <i>;; The object 'name'</i>
-}
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([5 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 32,
+ uint 32,
+ uint 0,
+ uint 2 }, section "llvm.metadata"
+%str1 = internal constant [5 x sbyte] c"bool\00", section "llvm.metadata"
</pre>
-<p>The first field contains a tag for the descriptor. The second field contains
-either a pointer to the descriptor for the containing <a
-href="#format_common_source_files">source file</a>, or it contains a pointer to
-another program object whose context pointer eventually reaches a source file.
-Through this <a href="#format_common_object_contexts">context</a> pointer, the
-LLVM debugger can establish the debug version number of the object.</p>
-
-<p>The third field contains a string that the debugger can use to identify the
-object if it does not contain explicit support for the source-language in use
-(ie, the 'unknown' source language handler uses this string). This should be
-some sort of unmangled string that corresponds to the object, but it is a
-quality of implementation issue what exactly it contains (it is legal, though
-not useful, for all of these strings to be null).</p>
-
-<p>Note again that descriptors can be extended to include
-source-language-specific information in addition to the fields required by the
-LLVM debugger. See the <a href="#ccxx_descriptors">section on the C/C++
-front-end</a> for more information. Also remember that global objects
-(functions, selectors, global variables, etc) must contain an <a
-href="format_common_anchors">anchor</a> to the <tt>llvm.dbg.globals</tt>
-variable.</p>
</div>
-
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="format_common_object_contexts">Program object contexts</a>
+<div class="doc_subsubsection">
+ <a name="ccxx_basic_char">char</a>
</div>
<div class="doc_text">
+
<pre>
-Allow source-language specific contexts, use to identify namespaces etc
-Must end up in a source file descriptor.
-Debugger core ignores all unknown context objects.
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([5 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 8,
+ uint 8,
+ uint 0,
+ uint 6 }, section "llvm.metadata"
+%str1 = internal constant [5 x sbyte] c"char\00", section "llvm.metadata"
</pre>
+
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="format_common_intrinsics">Debugger intrinsic functions</a>
+<div class="doc_subsubsection">
+ <a name="ccxx_basic_unsigned_char">unsigned char</a>
</div>
<div class="doc_text">
-<pre>
-Define each intrinsics, as an extension of the language reference manual.
-llvm.dbg.stoppoint
-llvm.dbg.region.start
-llvm.dbg.region.end
-llvm.dbg.function.start
-llvm.dbg.declare
+<pre>
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([14 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 8,
+ uint 8,
+ uint 0,
+ uint 8 }, section "llvm.metadata"
+%str1 = internal constant [14 x sbyte] c"unsigned char\00", section "llvm.metadata"
</pre>
+
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="format_common_tags">Values for debugger tags</a>
+<div class="doc_subsubsection">
+ <a name="ccxx_basic_short">short</a>
</div>
<div class="doc_text">
-<p>Happen to be the same value as the similarly named Dwarf-3 tags, this may
-change in the future.</p>
+<pre>
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([10 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 16,
+ uint 16,
+ uint 0,
+ uint 5 }, section "llvm.metadata"
+%str1 = internal constant [10 x sbyte] c"short int\00", section "llvm.metadata"
+</pre>
+
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="ccxx_basic_unsigned_short">unsigned short</a>
+</div>
+
+<div class="doc_text">
<pre>
- <a name="tag_compile_unit">LLVM_COMPILE_UNIT</a> : 17
- <a name="tag_subprogram">LLVM_SUBPROGRAM</a> : 46
- <a name="tag_variable">LLVM_VARIABLE</a> : 52
-<!-- <a name="tag_formal_parameter">LLVM_FORMAL_PARAMETER : 5-->
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([19 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 16,
+ uint 16,
+ uint 0,
+ uint 7 }, section "llvm.metadata"
+%str1 = internal constant [19 x sbyte] c"short unsigned int\00", section "llvm.metadata"
</pre>
+
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="ccxx_basic_int">int</a>
+</div>
+<div class="doc_text">
+
+<pre>
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([4 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 32,
+ uint 32,
+ uint 0,
+ uint 5 }, section "llvm.metadata"
+%str1 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
+</pre>
-<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="ccxx_frontend">C/C++ front-end specific debug information</a>
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="ccxx_basic_unsigned_int">unsigned int</a>
</div>
<div class="doc_text">
-<p>The C and C++ front-ends represent information about the program in a format
-that is effectively identical to <a
-href="http://www.eagercon.com/dwarf/dwarf3std.htm">Dwarf 3.0</a> in terms of
-information content. This allows code generators to trivially support native
-debuggers by generating standard dwarf information, and contains enough
-information for non-dwarf targets to translate it as needed.</p>
+<pre>
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([13 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 32,
+ uint 32,
+ uint 0,
+ uint 7 }, section "llvm.metadata"
+%str1 = internal constant [13 x sbyte] c"unsigned int\00", section "llvm.metadata"
+</pre>
-<p>The basic debug information required by the debugger is (intentionally)
-designed to be as minimal as possible. This basic information is so minimal
-that it is unlikely that <b>any</b> source-language could be adequately
-described by it. Because of this, the debugger format was designed for
-extension to support source-language-specific information. The extended
-descriptors are read and interpreted by the <a
-href="#arch_info">language-specific</a> modules in the debugger if there is
-support available, otherwise it is ignored.</p>
-
-<p>This section describes the extensions used to represent C and C++ programs.
-Other languages could pattern themselves after this (which itself is tuned to
-representing programs in the same way that Dwarf 3 does), or they could choose
-to provide completely different extensions if they don't fit into the Dwarf
-model. As support for debugging information gets added to the various LLVM
-source-language front-ends, the information used should be documented here.</p>
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="ccxx_basic_long_long">long long</a>
+</div>
+
+<div class="doc_text">
+
+<pre>
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([14 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 64,
+ uint 64,
+ uint 0,
+ uint 5 }, section "llvm.metadata"
+%str1 = internal constant [14 x sbyte] c"long long int\00", section "llvm.metadata"
+</pre>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="ccxx_pse">Program Scope Entries</a>
+<div class="doc_subsubsection">
+ <a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
</div>
<div class="doc_text">
-<p>TODO</p>
+
+<pre>
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([23 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 64,
+ uint 64,
+ uint 0,
+ uint 7 }, section "llvm.metadata"
+%str1 = internal constant [23 x sbyte] c"long long unsigned int\00", section "llvm.metadata"
+</pre>
+
</div>
-<!-- -------------------------------------------------------------------------->
+<!-- ======================================================================= -->
<div class="doc_subsubsection">
- <a name="ccxx_compilation_units">Compilation unit entries</a>
+ <a name="ccxx_basic_float">float</a>
</div>
<div class="doc_text">
-<p>
-Translation units do not add any information over the standard <a
-href="#format_common_source_files">source file representation</a> already
-expected by the debugger. As such, it uses descriptors of the type specified,
-with a trailing <a href="#format_common_anchors">anchor</a>.
-</p>
+
+<pre>
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([6 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 32,
+ uint 32,
+ uint 0,
+ uint 4 }, section "llvm.metadata"
+%str1 = internal constant [6 x sbyte] c"float\00", section "llvm.metadata"
+</pre>
+
</div>
-<!-- -------------------------------------------------------------------------->
+<!-- ======================================================================= -->
<div class="doc_subsubsection">
- <a name="ccxx_modules">Module, namespace, and importing entries</a>
+ <a name="ccxx_basic_double">double</a>
</div>
<div class="doc_text">
-<p>TODO</p>
+
+<pre>
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([7 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 64,
+ uint 64,
+ uint 0,
+ uint 4 }, section "llvm.metadata"
+%str1 = internal constant [7 x sbyte] c"double\00", section "llvm.metadata"
+</pre>
+
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="ccxx_dataobjects">Data objects (program variables)</a>
+ <a name="ccxx_derived_types">C/C++ derived types</a>
</div>
<div class="doc_text">
-<p>TODO</p>
+
+<p>Given the following as an example of C/C++ derived type;</p>
+
+<pre>
+typedef const int *IntPtr;
+</pre>
+
+<p>a C/C++ front-end would generate the following descriptors;</p>
+
+<pre>
+;;
+;; Define the typedef "IntPtr".
+;;
+%<a href="#format_derived_type">llvm.dbg.derivedtype1</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
+ uint add(uint 22, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([7 x sbyte]* %str1, int 0, int 0),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ int 1,
+ uint 0,
+ uint 0,
+ uint 0,
+ { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype2</a> to { }*) }, section "llvm.metadata"
+%str1 = internal constant [7 x sbyte] c"IntPtr\00", section "llvm.metadata"
+
+;;
+;; Define the pointer type.
+;;
+%<a href="#format_derived_type">llvm.dbg.derivedtype2</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
+ uint add(uint 15, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* null,
+ { }* null,
+ int 0,
+ uint 32,
+ uint 32,
+ uint 0,
+ { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype3</a> to { }*) }, section "llvm.metadata"
+
+;;
+;; Define the const type.
+;;
+%<a href="#format_derived_type">llvm.dbg.derivedtype3</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
+ uint add(uint 38, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* null,
+ { }* null,
+ int 0,
+ uint 0,
+ uint 0,
+ uint 0,
+ { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype1</a> to { }*) }, section "llvm.metadata"
+
+;;
+;; Define the int type.
+;;
+%<a href="#format_basic_type">llvm.dbg.basictype1</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([4 x sbyte]* %str2, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 32,
+ uint 32,
+ uint 0,
+ uint 5 }, section "llvm.metadata"
+%str2 = internal constant [4 x sbyte] c"int\00", section "llvm.metadata"
+</pre>
+
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="ccxx_composite_types">C/C++ struct/union types</a>
</div>
+<div class="doc_text">
+
+<p>Given the following as an example of C/C++ struct type;</p>
+
+<pre>
+struct Color {
+ unsigned Red;
+ unsigned Green;
+ unsigned Blue;
+};
+</pre>
+
+<p>a C/C++ front-end would generate the following descriptors;</p>
+
+<pre>
+;;
+;; Define basic type for unsigned int.
+;;
+%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
+ uint add(uint 36, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([13 x sbyte]* %str1, int 0, int 0),
+ { }* null,
+ int 0,
+ uint 32,
+ uint 32,
+ uint 0,
+ uint 7 }, section "llvm.metadata"
+%str1 = internal constant [13 x sbyte] c"unsigned int\00", section "llvm.metadata"
+
+;;
+;; Define composite type for struct Color.
+;;
+%<a href="#format_composite_type">llvm.dbg.compositetype</a> = internal constant %<a href="#format_composite_type">llvm.dbg.compositetype.type</a> {
+ uint add(uint 19, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([6 x sbyte]* %str2, int 0, int 0),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ int 1,
+ uint 96,
+ uint 32,
+ uint 0,
+ { }* null,
+ { }* cast ([3 x { }*]* %llvm.dbg.array to { }*) }, section "llvm.metadata"
+%str2 = internal constant [6 x sbyte] c"Color\00", section "llvm.metadata"
+
+;;
+;; Define the Red field.
+;;
+%<a href="#format_derived_type">llvm.dbg.derivedtype1</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
+ uint add(uint 13, uint 262144),
+ { }* null,
+ sbyte* getelementptr ([4 x sbyte]* %str3, int 0, int 0),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ int 2,
+ uint 32,
+ uint 32,
+ uint 0,
+ { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
+%str3 = internal constant [4 x sbyte] c"Red\00", section "llvm.metadata"
+
+;;
+;; Define the Green field.
+;;
+%<a href="#format_derived_type">llvm.dbg.derivedtype2</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
+ uint add(uint 13, uint 262144),
+ { }* null,
+ sbyte* getelementptr ([6 x sbyte]* %str4, int 0, int 0),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ int 3,
+ uint 32,
+ uint 32,
+ uint 32,
+ { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
+%str4 = internal constant [6 x sbyte] c"Green\00", section "llvm.metadata"
+
+;;
+;; Define the Blue field.
+;;
+%<a href="#format_derived_type">llvm.dbg.derivedtype3</a> = internal constant %<a href="#format_derived_type">llvm.dbg.derivedtype.type</a> {
+ uint add(uint 13, uint 262144),
+ { }* null,
+ sbyte* getelementptr ([5 x sbyte]* %str5, int 0, int 0),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ int 4,
+ uint 32,
+ uint 32,
+ uint 64,
+ { }* cast (%<a href="#format_basic_type">llvm.dbg.basictype.type</a>* %<a href="#format_basic_type">llvm.dbg.basictype</a> to { }*) }, section "llvm.metadata"
+%str5 = internal constant [5 x sbyte] c"Blue\00", section "llvm.metadata"
+
+;;
+;; Define the array of fields used by the composite type Color.
+;;
+%llvm.dbg.array = internal constant [3 x { }*] [
+ { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype1</a> to { }*),
+ { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype2</a> to { }*),
+ { }* cast (%<a href="#format_derived_type">llvm.dbg.derivedtype.type</a>* %<a href="#format_derived_type">llvm.dbg.derivedtype3</a> to { }*) ], section "llvm.metadata"
+</pre>
+
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="ccxx_enumeration_types">C/C++ enumeration types</a>
+</div>
+
+<div class="doc_text">
+
+<p>Given the following as an example of C/C++ enumeration type;</p>
+
+<pre>
+enum Trees {
+ Spruce = 100,
+ Oak = 200,
+ Maple = 300
+};
+</pre>
+
+<p>a C/C++ front-end would generate the following descriptors;</p>
+
+<pre>
+;;
+;; Define composite type for enum Trees
+;;
+%<a href="#format_composite_type">llvm.dbg.compositetype</a> = internal constant %<a href="#format_composite_type">llvm.dbg.compositetype.type</a> {
+ uint add(uint 4, uint 262144),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ sbyte* getelementptr ([6 x sbyte]* %str1, int 0, int 0),
+ { }* cast (%<a href="#format_compile_units">llvm.dbg.compile_unit.type</a>* %<a href="#format_compile_units">llvm.dbg.compile_unit</a> to { }*),
+ int 1,
+ uint 32,
+ uint 32,
+ uint 0,
+ { }* null,
+ { }* cast ([3 x { }*]* %llvm.dbg.array to { }*) }, section "llvm.metadata"
+%str1 = internal constant [6 x sbyte] c"Trees\00", section "llvm.metadata"
+
+;;
+;; Define Spruce enumerator.
+;;
+%<a href="#format_enumeration">llvm.dbg.enumerator1</a> = internal constant %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> {
+ uint add(uint 40, uint 262144),
+ sbyte* getelementptr ([7 x sbyte]* %str2, int 0, int 0),
+ int 100 }, section "llvm.metadata"
+%str2 = internal constant [7 x sbyte] c"Spruce\00", section "llvm.metadata"
+
+;;
+;; Define Oak enumerator.
+;;
+%<a href="#format_enumeration">llvm.dbg.enumerator2</a> = internal constant %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> {
+ uint add(uint 40, uint 262144),
+ sbyte* getelementptr ([4 x sbyte]* %str3, int 0, int 0),
+ int 200 }, section "llvm.metadata"
+%str3 = internal constant [4 x sbyte] c"Oak\00", section "llvm.metadata"
+
+;;
+;; Define Maple enumerator.
+;;
+%<a href="#format_enumeration">llvm.dbg.enumerator3</a> = internal constant %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> {
+ uint add(uint 40, uint 262144),
+ sbyte* getelementptr ([6 x sbyte]* %str4, int 0, int 0),
+ int 300 }, section "llvm.metadata"
+%str4 = internal constant [6 x sbyte] c"Maple\00", section "llvm.metadata"
+
+;;
+;; Define the array of enumerators used by composite type Trees.
+;;
+%llvm.dbg.array = internal constant [3 x { }*] [
+ { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator1</a> to { }*),
+ { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator2</a> to { }*),
+ { }* cast (%<a href="#format_enumeration">llvm.dbg.enumerator.type</a>* %<a href="#format_enumeration">llvm.dbg.enumerator3</a> to { }*) ], section "llvm.metadata"
+</pre>
+
+</div>
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<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
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