<div class="doc_title">Source Level Debugging with LLVM</div>
+<table class="layout" style="width:100%">
+ <tr class="layout">
+ <td class="left">
<ul>
-
-<img src="venusflytrap.jpg" width=247 height=369 align=right>
-
- <li><a href="#introduction">Introduction</a></li>
+ <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><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></li>
- <ol>
- <li><a href="#arch_todo">Short-term TODO list</a></li>
- </ol>
-
- <li><a href="#implementation">Debugging information implementation</a></li>
+ <li><a href="#format">Debugging information format</a>
<ol>
- <li><a href="#impl_common_anchors">Anchors for global objects</a></li>
- <li><a href="#impl_common_stoppoint">Representing stopping points in the source program</a></li>
- <li><a href="#impl_common_lifetime">Object lifetimes and scoping</a></li>
- <li><a href="#impl_common_descriptors">Object descriptor formats</a></li>
+ <li><a href="#debug_info_descriptors">Debug information descriptors</a>
<ul>
- <li><a href="#impl_common_source_files">Representation of source files</a></li>
- <li><a href="#impl_common_globals">Representation of global objects</a></li>
- <li><a href="#impl_common_localvars">Representation of local variables</a></li>
- </ul>
- <li><a href="#impl_common_intrinsics">Other intrinsic functions</a></li>
- </ol>
- <li><a href="#impl_ccxx">C/C++ front-end specific debug information</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>
+ <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="#impl_ccxx_descriptors">Object descriptor formats</a></li>
- </ol>
+ <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 class="right">
+<img src="img/venusflytrap.jpg" alt="A leafy and green bug eater" width="247"
+height="369">
+</td>
+</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 how to use 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. When compiling a program in debug mode, the front-end in use adds
-LLVM debugging information to the program in the form of normal <a
-href="LangRef.html">LLVM program objects</a> as well as a small set of LLVM <a
-href="#implementation">intrinsic functions</a>, which specify the mapping of the
-program in LLVM form to the program in the source language.
-</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>
<div class="doc_text">
-<p>
-The idea of the LLVM debugging information is to capture how the important
+<p>The idea of the LLVM debugging information is to capture how the important
pieces of the source-language's Abstract Syntax Tree map onto LLVM code.
Several design aspects have shaped the solution that appears here. The
important ones are:</p>
-<p><ul>
+<ul>
<li>Debugging information should have very little impact on the rest of the
compiler. No transformations, analyses, or code generators should need to be
modified because of debugging information.</li>
the debugging information should work with any language.</li>
<li>With code generator support, it should be possible to use an LLVM compiler
-to compile a program to native machine code with standard debugging formats.
+to compile a program to native machine code and standard debugging formats.
This allows compatibility with traditional machine-code level debuggers, like
GDB or DBX.</li>
-</ul></p>
+</ul>
-<p>
-The approach used by the LLVM implementation is to use a small set of <a
-href="#impl_common_intrinsics">intrinsic functions</a> to define a mapping
+<p>The approach used by the LLVM implementation is to use a small set of <a
+href="#format_common_intrinsics">intrinsic functions</a> to define a mapping
between LLVM program objects and the source-level objects. The description of
the source-level program is maintained in LLVM global variables in an <a
-href="#impl_ccxx">implementation-defined format</a> (the C/C++ front-end
+href="#ccxx_frontend">implementation-defined format</a> (the C/C++ front-end
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">
</div>
<div class="doc_text">
-<p>
-An extremely high priority of LLVM debugging information is to make it interact
-well with optimizations and analysis. In particular, the LLVM debug information
-provides the following guarantees:</p>
-<p><ul>
+<p>An extremely high priority of LLVM debugging information is to make it
+interact well with optimizations and analysis. In particular, the LLVM debug
+information provides the following guarantees:</p>
+
+<ul>
<li>LLVM debug information <b>always provides information to accurately read the
source-level state of the program</b>, regardless of which LLVM optimizations
automatically merged by the linker, and unused information is automatically
removed.</li>
-</ul></p>
+</ul>
-<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 "<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 and call
-functions where were optimized out of the program, or inlined away completely.
-</p>
+<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 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
+and call functions where were optimized out of the program, or inlined away
+completely.</p>
</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>
-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>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>
-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 that is
-compatible with the LLVM license).</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>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
-seperated from the <tt>llvm-db</tt> front-end. A GUI debugger or IDE would be
-an interesting project.
-</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>
-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><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>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><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>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 the first LLVM debugger, and as such was designed to be
-quick to prototype and build, and simple to extend. It is missing many many
-features, though they should be easy to add over time (patches welcomed!).
-Because the (currently only) debugger backend (implemented in
-"lib/Debugger/UnixLocalInferiorProcess.cpp") was designed to work without any
-cooperation from the code generators, 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>
+
+<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>
+
+<p>The following names are recognized as anchors by LLVM:</p>
+
+<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>
+
+<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>
-<p><ul>
+</div>
-<li>Running a program in <tt>llvm-db</tt> is a bit slower than running it with
-<tt>lli</tt>.</li>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_compile_units">Compile unit descriptors</a>
+</div>
-<li>Inspection of the target hardware is not supported. This means that you
-cannot, for example, print the contents of X86 registers.</li>
+<div class="doc_text">
-<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>
+<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>
+
+<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>
-<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_global_variables">Global variable descriptors</a>
+</div>
-</ul></p>
+<div class="doc_text">
-<p>That said, it is still quite useful, and all of these limitations can be
-eliminated by integrating support for the debugger into the code generators.
-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_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_subsection">
- <a name="sample">A sample <tt>llvm-db</tt> session</a>
+<div class="doc_subsubsection">
+ <a name="format_subprograms">Subprogram descriptors</a>
</div>
<div class="doc_text">
-<p>
-TODO
-</p>
+<pre>
+ %<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>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>The type encoding provides the details of the type. The values are typically
+one of the following;</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>
-<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>
+</div>
-<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>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_derived_type">Derived type descriptors</a>
+</div>
+
+<div class="doc_text">
-<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>
+ %<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>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>
+
+<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>
+
+<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>
+
+<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>
+
+<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_subsection">
- <a name="commands">Commands recognized by the debugger</a>
+<div class="doc_subsubsection">
+ <a name="format_composite_type">Composite 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_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>
-<p>
-<h2>General usage:</h2>
-<ul>
-<li>help [command]</li>
-<li>quit</li>
-<li><a name="c_file">file</a> [program]</li>
-</ul>
+</div>
-<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>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_subrange">Subrange descriptors</a>
+</div>
-<h2>Call stack inspection:</h2>
-<ul>
-<li>backtrace</li>
-<li>up [n]</li>
-<li>down [n]</li>
-<li>frame [n]</li>
-</ul>
+<div class="doc_text">
+<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>
-<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>
-</ul>
+<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>
-<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>
</div>
-<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="architecture">Architecture of the LLVM debugger</a>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_enumeration">Enumerator descriptors</a>
</div>
-<!-- *********************************************************************** -->
<div class="doc_text">
-<p><pre>
-lib/Debugger
- - UnixLocalInferiorProcess.cpp
+<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>
-tools/llvm-db
- - SourceLanguage interfaces
- - ProgramInfo/RuntimeInfo
- - Commands
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_variables">Local variables</a>
+</div>
-</pre></p>
+<div class="doc_text">
+<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>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
+provide debug information at various points in generated code.</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>
+</div>
-<p>
-<b>run (with args)</b> & <b>set args</b>: These need to be implemented.
-Currently run doesn't support setting arguments as part of the command. The
-only tricky thing is handling quotes right and stuff.</p>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_common_stoppoint">llvm.dbg.stoppoint</a>
+</div>
-<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>
+<div class="doc_text">
+<pre>
+ void %<a href="#format_common_stoppoint">llvm.dbg.stoppoint</a>( uint, uint, { }* )
+</pre>
+
+<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>
</div>
-<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="implementation">Debugging information implementation</a>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_common_func_start">llvm.dbg.func.start</a>
</div>
-<!-- *********************************************************************** -->
<div class="doc_text">
+<pre>
+ void %<a href="#format_common_func_start">llvm.dbg.func.start</a>( { }* )
+</pre>
+
+<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
+defines the beginning of the function's declarative region (scope). It also
+implies a call to %<tt><a
+href="#format_common_stoppoint">llvm.dbg.stoppoint</a></tt> which defines a
+source line "stop point". 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>
-<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>
+</div>
-<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 class="doc_subsubsection">
+ <a name="format_common_region_start">llvm.dbg.region.start</a>
+</div>
-<p>The debugger is designed to be agnostic about the contents of most of the
-debugging information. It uses a source-language-specific module 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_text">
+<pre>
+ void %<a href="#format_common_region_start">llvm.dbg.region.start</a>( { }* )
+</pre>
-<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="#impl_common_source_files">source files</a>, <a
-href="#impl_common_globals">global objects</a> (aka methods, messages, global
-variables, etc), and <a href="#impl_common_localvars">local variables</a>.
-These abstract objects are used by the debugger to form stack traces, show
-information about local variables, etc.
+<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>
-<p>This section of the documentation first describes the representation aspects
-<a href="#impl_common">common to any source-language</a>. The next section
-describes the data layout conventions used by the <a href="#impl_ccxx">C and C++
-front-ends</a>.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="impl_common_anchors">Anchors for global objects</a>
+<div class="doc_subsubsection">
+ <a name="format_common_region_end">llvm.dbg.region.end</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_end">llvm.dbg.region.end</a>( { }* )
+</pre>
+
+<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>
-<p>
-So far, the following names are recognized as anchors by the LLVM debugger:
-</p>
+</div>
-<p><pre>
- %<a href="#impl_common_source_files">llvm.dbg.translation_units</a> = linkonce global {} {}
- %<a href="#impl_common_globals">llvm.dbg.globals</a> = linkonce global {} {}
-</pre></p>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="format_common_declare">llvm.dbg.declare</a>
+</div>
-<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>
+<div class="doc_text">
+<pre>
+ void %<a href="#format_common_declare">llvm.dbg.declare</a>( { } *, { }* )
+</pre>
-</div>
+<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="impl_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 was evaluated), but it is
-recommended to only put them after every source statement.</p>
-
-<p>
-Using calls to this intrinsic function to demark legal points for the debugger
-to inspect the program automatically disables any optimizations that could
-potentially confuse debugging information. To non-debug-information-aware
+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
+could potentially confuse debugging information. To non-debug-information-aware
transformations, these calls simply look like calls to an external function,
which they must assume to do anything (including reading or writing to any part
of reachable memory). On the other hand, it does not impact many optimizations,
such as code motion of non-trapping instructions, nor does it impact
-optimization of subexpressions, or any other code between the stop points.</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 <a
-href="#impl_common_lifetime">the next section</a>.</p>
+optimization of subexpressions, code duplication transformations, or basic-block
+reordering transformations.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="impl_common_lifetime">Object lifetimes and scoping</a>
+ <a name="format_common_lifetime">Object lifetimes and scoping</a>
</div>
<div class="doc_text">
-<p>
-In many languages, the local variables in functions can have their lifetime or
-scope limited to a subset of a function. In the C family of languages, for
+<p>In many languages, the local variables in functions can have their lifetime
+or scope limited to a subset of a function. In the C family of languages, for
example, variables are only live (readable and writable) within the source block
that they are defined in. In functional languages, values are only readable
after they have been defined. Though this is a very obvious concept, it is also
non-trivial to model in LLVM, because it has no notion of scoping in this sense,
-and does not want to be tied to a language's scoping rules.
-</p>
+and does not want to be tied to a language's scoping rules.</p>
-<p>
-In order to handle this, the LLVM debug format uses the notion of "regions" of a
-function, delineated by calls to intrinsic functions. These intrinsic functions
-define new regions of the program and indicate when the region lifetime expires.
-Consider the following C fragment, for example:
-</p>
+<p>In order to handle this, the LLVM debug format uses the notion of "regions"
+of a function, delineated by calls to intrinsic functions. These intrinsic
+functions define new regions of the program and indicate when the region
+lifetime expires. Consider the following C fragment, for example:</p>
-<p><pre>
+<pre>
1. void foo() {
2. int X = ...;
3. int Y = ...;
7. }
8. ...
9. }
-</pre></p>
+</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>
-<p><pre>
+<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="#impl_common_globals">%lldb.global</a>* %d.foo)
- %D2 = call {}* <a href="#impl_common_stoppoint">%llvm.dbg.stoppoint</a>({}* %D1, uint 2, uint 2, <a href="#impl_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="#impl_common_stoppoint">%llvm.dbg.stoppoint</a>({}* %D3, uint 3, uint 2, <a href="#impl_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="#impl_common_stoppoint">%llvm.dbg.stoppoint</a>({}* %D5, uint 5, uint 4, <a href="#impl_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="#impl_common_stoppoint">%llvm.dbg.stoppoint</a>({}* %D8, uint 6, uint 4, <a href="#impl_common_source_files">%lldb.compile_unit</a>* %file)
-
- <i>;; Code for line 6.</i>
- %D10 = call {}* %llvm.region.end({}* %D9)
- %D11 = call {}* <a href="#impl_common_stoppoint">%llvm.dbg.stoppoint</a>({}* %D10, uint 8, uint 2, <a href="#impl_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>
-
-<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="#impl_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="#impl_common_globals">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>
-
-<p>
-Representing the boundaries of functions with regions allows normal LLVM
-interprocedural optimizations to change the boundaries of functions without
-having to worry about breaking mapping information between LLVM and source-level
-functions. In particular, the inlining optimization requires no modification to
-support inlining with debugging information: there is no correlation drawn
-between LLVM functions and their source-level counterparts.</p>
-
-<p>
-Once the function has been defined, the <a
-href="#impl_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
+</pre>
+
+<p>This example illustrates a few important details about the LLVM debugging
+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
+having to worry about breaking mapping information between the LLVM code and the
+and source-level program. In particular, the inliner requires no modification
+to support inlining with debugging information: there is no explicit correlation
+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 a debugger).</p>
+
+<p>Once the function has been defined, the <a
+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>
+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 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 could change how name lookup is
+performed.</p>
+
+</div>
-<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. Through the use of LLVM debugger regions,
-arbitrary source-language scoping rules can be supported, 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 yet implemented).
-</p>
+<!-- *********************************************************************** -->
+<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="impl_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 global objects to start in a
-canonical format, but the descriptors can include additional information
-appended at the end. All LLVM debugging information is versioned, allowing
-backwards compatibility in the case that the core structures need to change in
-some way. The lowest-level descriptor are those describing <a
-href="#impl_common_source_files">the files containing the program source
-code</a>, all other descriptors 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">
-<!----------------------------------------------------------------------------->
-<div class="doc_subsubsection">
- <a name="impl_common_source_files">Representation of source files</a>
+<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>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="ccxx_subprogram">C/C++ function information</a>
</div>
<div class="doc_text">
-<p>
-Source file descriptors were roughly patterned after the Dwarf "compile_unit"
-object. The descriptor currently is defined to have the following LLVM
-type:</p>
-<p><pre>
-%lldb.compile_unit = type {
- 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>
- {}* <i>;; Anchor for llvm.dbg.translation_units</i>
+<p>Given a function declared as follows;</p>
+
+<pre>
+int main(int argc, char *argv[]) {
+ return 0;
}
-</pre></p>
-
-<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, and the <a
-href="#impl_common_anchors">anchor</a> for the descriptor. Here is an example
-descriptor:
-</p>
-
-<p><pre>
-%arraytest_source_file = internal constant %lldb.compile_unit {
- 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
+</pre>
+
+<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>
+
+</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="ccxx_basic_type_bool">bool</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 ([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>
+
+</div>
+
+<!-- ======================================================================= -->
<div class="doc_subsubsection">
- <a name="impl_common_globals">Representation of global objects</a>
+ <a name="ccxx_basic_char">char</a>
</div>
<div class="doc_text">
-<p>
-The LLVM debugger needs to know what the source-language global objects, in
-order to build stack traces and other related activities. Because
-source-languages have widly varying forms of global objects, the LLVM debugger
-only expects the following fields in the descriptor for each global:
-</p>
-<p><pre>
-%lldb.global = type {
- <a href="#impl_common_source_files">%lldb.compile_unit</a>*, <i>;; The translation unit containing the global</i>
- sbyte*, <i>;; The global object 'name'</i>
- [type]*, <i>;; Source-language type descriptor for global</i>
- {}* <i>;; The anchor for llvm.dbg.globals</i>
-}
-</pre></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 ([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_subsubsection">
+ <a name="ccxx_basic_unsigned_char">unsigned char</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 8,
+ uint 8,
+ uint 0,
+ uint 8 }, section "llvm.metadata"
+%str1 = internal constant [14 x sbyte] c"unsigned char\00", section "llvm.metadata"
+</pre>
-<p>
-The first field contains a pointer to the translation unit the function is
-defined in. This pointer allows the debugger to find out which version of debug
-information the function corresponds to. The second field contains a string
-that the debugger can use to identify the subprogram if it does not contain
-explicit support for the source-language in use. This should be some sort of
-unmangled string that corresponds to the function somehow.
-</p>
+</div>
-<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="#impl_ccxx_descriptors">section on the C/C++ front-end</a> for more
-information.
-</p>
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="ccxx_basic_short">short</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 ([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="impl_common_localvars">Representation of local variables</a>
+ <a name="ccxx_basic_unsigned_short">unsigned short</a>
</div>
<div class="doc_text">
-<p>
-</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 ([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>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="impl_common_intrinsics">Other intrinsic functions</a>
+<div class="doc_subsubsection">
+ <a name="ccxx_basic_unsigned_int">unsigned int</a>
</div>
<div class="doc_text">
-<p>
-</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>
+
</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 class="doc_section">
- <a name="impl_ccxx">C/C++ front-end specific debug information</a>
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsubsection">
+ <a name="ccxx_basic_unsigned_long_long">unsigned long long</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 other 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 ([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_basic_float">float</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 ([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_basic_double">double</a>
+</div>
+
+<div class="doc_text">
-<p>
-TODO: document extensions to standard debugging objects, document how we
-represent source types, etc.
-</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="impl_ccxx_descriptors">Object Descriptor Formats</a>
+ <a name="ccxx_derived_types">C/C++ derived types</a>
</div>
<div class="doc_text">
-<p>
-</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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