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<head>
+ <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Source Level Debugging with LLVM</title>
<link rel="stylesheet" href="llvm.css" type="text/css">
</head>
<body>
-<div class="doc_title">Source Level Debugging with LLVM</div>
+<h1>Source Level Debugging with LLVM</h1>
<table class="layout" style="width:100%">
<tr class="layout">
<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>
</ol></li>
<li><a href="#format">Debugging information format</a>
<ol>
<li><a href="#debug_info_descriptors">Debug information descriptors</a>
<ul>
- <li><a href="#format_anchors">Anchor descriptors</a></li>
<li><a href="#format_compile_units">Compile unit descriptors</a></li>
+ <li><a href="#format_files">File 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_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>
+ <li><a href="#format_common_value">llvm.dbg.value</a></li>
</ul></li>
- <li><a href="#format_common_stoppoints">Representing stopping points in the
- source program</a></li>
</ol></li>
+ <li><a href="#format_common_lifetime">Object lifetimes and scoping</a></li>
<li><a href="#ccxx_frontend">C/C++ front-end specific debug information</a>
<ol>
<li><a href="#ccxx_compile_units">C/C++ source file information</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>
+ <li><a href="#llvmdwarfextension">LLVM Dwarf Extensions</a>
+ <ol>
+ <li><a href="#objcproperty">Debugging Information Extension
+ for Objective C Properties</a></li>
+ <ul>
+ <li><a href="#objcpropertyintroduction">Introduction</a></li>
+ <li><a href="#objcpropertyproposal">Proposal</a></li>
+ <li><a href="#objcpropertynewattributes">New DWARF Attributes</a></li>
+ <li><a href="#objcpropertynewconstants">New DWARF Constants</a></li>
+ </ul>
+
+ </ol>
+ </li>
</ul>
</td>
<td class="right">
<div class="doc_author">
<p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
- and <a href="mailto:jlaskey@apple.com">Jim Laskey</a></p>
+ and <a href="mailto:jlaskey@mac.com">Jim Laskey</a></p>
</div>
<!-- *********************************************************************** -->
-<div class="doc_section"><a name="introduction">Introduction</a></div>
+<h2><a name="introduction">Introduction</a></h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>This document is the central repository for all information pertaining to
-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>
+ 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 specific examples of what debug information
+ for C/C++ looks like.</p>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="phil">Philosophy behind LLVM debugging information</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<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>
+ 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>
<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>
-
-<li>LLVM optimizations should interact in <a href="#debugopt">well-defined and
-easily described ways</a> with the debugging information.</li>
+ <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>
-<li>Because LLVM is designed to support arbitrary programming languages,
-LLVM-to-LLVM tools should not need to know anything about the semantics of the
-source-level-language.</li>
+ <li>LLVM optimizations should interact in <a href="#debugopt">well-defined and
+ easily described ways</a> with the debugging information.</li>
-<li>Source-level languages are often <b>widely</b> different from one another.
-LLVM should not put any restrictions of the flavor of the source-language, and
-the debugging information should work with any language.</li>
+ <li>Because LLVM is designed to support arbitrary programming languages,
+ LLVM-to-LLVM tools should not need to know anything about the semantics of
+ the source-level-language.</li>
-<li>With code generator support, it should be possible to use an LLVM compiler
-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>
+ <li>Source-level languages are often <b>widely</b> different from one another.
+ LLVM should not put any restrictions of the flavor of the source-language,
+ and 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 and standard debugging
+ formats. This allows compatibility with traditional machine-code level
+ debuggers, like GDB or DBX.</li>
</ul>
-<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="#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>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 metadata
+ in an <a 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 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>
+ 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 or family of languages.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="debugopt">Debugging optimized code</a>
+<h3>
+ <a name="consumers">Debug information consumers</a>
+</h3>
+
+<div>
+
+<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 DwarfDebug 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_text">
+<!-- ======================================================================= -->
+<h3>
+ <a name="debugopt">Debugging optimized code</a>
+</h3>
+
+<div>
<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>
+ 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
-have been run, and without any modification to the optimizations themselves.
-However, some optimizations may impact the ability to modify the current state
-of the program with a debugger, such as setting program variables, or calling
-function that have been deleted.</li>
-
-<li>LLVM optimizations gracefully interact with debugging information. If they
-are not aware of debug information, they are automatically disabled as necessary
-in the cases that would invalidate the debug info. This retains the LLVM
-features making it easy to write new transformations.</li>
-
-<li>As desired, LLVM optimizations can be upgraded to be aware of the LLVM
-debugging information, allowing them to update the debugging information as they
-perform aggressive optimizations. This means that, with effort, the LLVM
-optimizers could optimize debug code just as well as non-debug code.</li>
-
-<li>LLVM debug information does not prevent many important optimizations from
-happening (for example inlining, basic block reordering/merging/cleanup, tail
-duplication, etc), further reducing the amount of the compiler that eventually
-is "aware" of debugging information.</li>
-
-<li>LLVM debug information is automatically optimized along with the rest of the
-program, using existing facilities. For example, duplicate information is
-automatically merged by the linker, and unused information is automatically
-removed.</li>
-
+ <li>LLVM debug information <b>always provides information to accurately read
+ the source-level state of the program</b>, regardless of which LLVM
+ optimizations have been run, and without any modification to the
+ optimizations themselves. However, some optimizations may impact the
+ ability to modify the current state of the program with a debugger, such
+ as setting program variables, or calling functions that have been
+ deleted.</li>
+
+ <li>As desired, LLVM optimizations can be upgraded to be aware of the LLVM
+ debugging information, allowing them to update the debugging information
+ as they perform aggressive optimizations. This means that, with effort,
+ the LLVM optimizers could optimize debug code just as well as non-debug
+ code.</li>
+
+ <li>LLVM debug information does not prevent optimizations from
+ happening (for example inlining, basic block reordering/merging/cleanup,
+ tail duplication, etc).</li>
+
+ <li>LLVM debug information is automatically optimized along with the rest of
+ the program, using existing facilities. For example, duplicate
+ information is automatically merged by the linker, and unused information
+ is automatically removed.</li>
</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 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>
+ "<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>
+
+<p><a href="TestingGuide.html#quicktestsuite">LLVM test suite</a> provides a
+ framework to test optimizer's handling of debugging information. It can be
+ run like this:</p>
+
+<div class="doc_code">
+<pre>
+% cd llvm/projects/test-suite/MultiSource/Benchmarks # or some other level
+% make TEST=dbgopt
+</pre>
+</div>
+
+<p>This will test impact of debugging information on optimization passes. If
+ debugging information influences optimization passes then it will be reported
+ as a failure. See <a href="TestingGuide.html">TestingGuide</a> for more
+ information on LLVM test infrastructure and how to run various tests.</p>
+
+</div>
</div>
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="format">Debugging information format</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<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>
+ for the optimizer to optimize the program and debugging information without
+ necessarily having to know anything about debugging information. In
+ particular, the use of metadata avoids duplicated debugging information from
+ the beginning, and the global dead code elimination pass automatically
+ deletes debugging information for a function if it decides to delete the
+ function. </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>
+ variables, functions, source files, etc) is inserted by the language
+ front-end in the form of LLVM metadata. </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>
+ debugging information representation (e.g. DWARF/Stabs/etc). It uses a
+ generic 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. </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>
+ 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_files">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>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>
+ 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 class="doc_subsection">
+<h3>
<a name="debug_info_descriptors">Debug information descriptors</a>
-</div>
+</h3>
+
+<div>
-<div class="doc_text">
<p>In consideration of the complexity and volume of debug information, LLVM
-provides a specification for well formed debug global variables. The constant
-value of each of these globals is one of a limited set of structures, known as
-debug descriptors.</p>
+ provides a specification for well formed 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.</p>
-
-<p>The fields of debug descriptors used internally by LLVM (MachineDebugInfo)
-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>
-
+ 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 through 0x2000 (there is a defined enum DW_TAG_user_base =
+ 0x1000.)</p>
+
+<p>The fields of debug descriptors used internally by LLVM
+ are restricted to only the simple data types <tt>i32</tt>, <tt>i1</tt>,
+ <tt>float</tt>, <tt>double</tt>, <tt>mdstring</tt> and <tt>mdnode</tt>. </p>
+
+<div class="doc_code">
<pre>
- %llvm.dbg.object.type = type {
- uint, ;; A tag
- ...
- }
+!1 = metadata !{
+ i32, ;; A tag
+ ...
+}
</pre>
+</div>
-<p>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.</p>
-
-<p>The details of the various descriptors follow.</p>
+<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
+ <tt>i32</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 = 8 << 16 or
+ 0x80000 or 524288.)</a></p>
-</div>
+<p>The details of the various descriptors follow.</p>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
- <a name="format_anchors">Anchor descriptors</a>
-</div>
+<h4>
+ <a name="format_compile_units">Compile unit descriptors</a>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
- %<a href="#format_anchors">llvm.dbg.anchor.type</a> = type {
- uint, ;; Tag = 0
- uint ;; Tag of descriptors grouped by the anchor
- }
+!0 = metadata !{
+ i32, ;; Tag = 17 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
+ ;; (DW_TAG_compile_unit)
+ i32, ;; Unused field.
+ i32, ;; DWARF language identifier (ex. DW_LANG_C89)
+ metadata, ;; Source file name
+ metadata, ;; Source file directory (includes trailing slash)
+ metadata ;; Producer (ex. "4.0.1 LLVM (LLVM research group)")
+ i1, ;; True if this is a main compile unit.
+ i1, ;; True if this is optimized.
+ metadata, ;; Flags
+ i32 ;; Runtime version
+ metadata ;; List of enums types
+ metadata ;; List of retained types
+ metadata ;; List of subprograms
+ metadata ;; List of global variables
+}
</pre>
+</div>
-<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>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>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>Compile unit descriptors provide the root context for objects declared in a
+ specific compilation unit. File descriptors are defined using this context.
+ These descriptors are collected by a named metadata
+ <tt>!llvm.dbg.cu</tt>. Compile unit descriptor keeps track of subprograms,
+ global variables and type information.
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
- <a name="format_compile_units">Compile unit descriptors</a>
-</div>
+<h4>
+ <a name="format_files">File descriptors</a>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
- %<a href="#format_compile_units">llvm.dbg.compile_unit.type</a> = type {
- uint, ;; Tag = 17 (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, ;; LLVM debug version number = 2
- 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)")
- }
+!0 = metadata !{
+ i32, ;; Tag = 41 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
+ ;; (DW_TAG_file_type)
+ metadata, ;; Source file name
+ metadata, ;; Source file directory (includes trailing slash)
+ metadata ;; Unused
+}
</pre>
+</div>
-<p>These descriptors contain the version number for the debug info (currently
-2), 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>These descriptors contain information for a file. Global variables and top
+ level functions would be defined using this context.k File descriptors also
+ provide context for source line correspondence. </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>
+<p>Each input file is encoded as a separate file descriptor in LLVM debugging
+ information output. </p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="format_global_variables">Global variable descriptors</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
- %<a href="#format_global_variables">llvm.dbg.global_variable.type</a> = type {
- uint, ;; Tag = 52 (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
- { }*, ;; Reference to compile unit where defined
- int, ;; 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
- }
+!1 = metadata !{
+ i32, ;; Tag = 52 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
+ ;; (DW_TAG_variable)
+ i32, ;; Unused field.
+ metadata, ;; Reference to context descriptor
+ metadata, ;; Name
+ metadata, ;; Display name (fully qualified C++ name)
+ metadata, ;; MIPS linkage name (for C++)
+ metadata, ;; Reference to file where defined
+ i32, ;; Line number where defined
+ metadata, ;; Reference to type descriptor
+ i1, ;; True if the global is local to compile unit (static)
+ i1, ;; True if the global is defined in the compile unit (not extern)
+ {}* ;; Reference to the global variable
+}
</pre>
+</div>
<p>These descriptors provide debug information about globals variables. The
-provide details such as name, type and where the variable is defined.</p>
+provide details such as name, type and where the variable is defined. All
+global variables are collected by named metadata <tt>!llvm.dbg.gv</tt>.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="format_subprograms">Subprogram descriptors</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
- %<a href="#format_subprograms">llvm.dbg.subprogram.type</a> = type {
- uint, ;; Tag = 46 (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
- { }*, ;; Reference to compile unit where defined
- int, ;; 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 array of member descriptors
- }
+!2 = metadata !{
+ i32, ;; Tag = 46 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
+ ;; (DW_TAG_subprogram)
+ i32, ;; Unused field.
+ metadata, ;; Reference to context descriptor
+ metadata, ;; Name
+ metadata, ;; Display name (fully qualified C++ name)
+ metadata, ;; MIPS linkage name (for C++)
+ metadata, ;; Reference to file where defined
+ i32, ;; Line number where defined
+ metadata, ;; Reference to type descriptor
+ i1, ;; True if the global is local to compile unit (static)
+ i1, ;; True if the global is defined in the compile unit (not extern)
+ i32, ;; Virtuality, e.g. dwarf::DW_VIRTUALITY__virtual
+ i32, ;; Index into a virtual function
+ metadata, ;; indicates which base type contains the vtable pointer for the
+ ;; derived class
+ i32, ;; Flags - Artifical, Private, Protected, Explicit, Prototyped.
+ i1, ;; isOptimized
+ Function *,;; Pointer to LLVM function
+ metadata, ;; Lists function template parameters
+ metadata ;; Function declaration descriptor
+ metadata ;; List of function variables
+}
</pre>
+</div>
<p>These descriptors provide debug information about functions, methods and
-subprograms. The provide details such as name, return and argument types and
-where the subprogram is defined.</p>
-
-<p>The array of member descriptors is used to define arguments local variables
-and nested blocks.</p>
+ subprograms. They provide details such as name, return types and the source
+ location where the subprogram is defined.
+</p>
</div>
+
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="format_blocks">Block descriptors</a>
+</h4>
+
+<div>
+
+<div class="doc_code">
+<pre>
+!3 = metadata !{
+ i32, ;; Tag = 11 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
+ metadata,;; Reference to context descriptor
+ i32, ;; Line number
+ i32, ;; Column number
+ metadata,;; Reference to source file
+ i32 ;; Unique ID to identify blocks from a template function
+}
+</pre>
</div>
-<div class="doc_text">
+<p>This descriptor provides debug information about nested blocks within a
+ subprogram. The line number and column numbers are used to dinstinguish
+ two lexical blocks at same depth. </p>
+<div class="doc_code">
<pre>
- %<a href="#format_blocks">llvm.dbg.block</a> = type {
- uint, ;; Tag = 13 (DW_TAG_lexical_block)
- { }* ;; Reference to array of member descriptors
- }
+!3 = metadata !{
+ i32, ;; Tag = 11 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
+ metadata ;; Reference to the scope we're annotating with a file change
+ metadata,;; Reference to the file the scope is enclosed in.
+}
</pre>
+</div>
-<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>
+<p>This descriptor provides a wrapper around a lexical scope to handle file
+ changes in the middle of a lexical block.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="format_basic_type">Basic type descriptors</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
- %<a href="#format_basic_type">llvm.dbg.basictype.type</a> = type {
- uint, ;; Tag = 36 (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)
- int, ;; Line number where defined (may be 0)
- uint, ;; Size in bits
- uint, ;; Alignment in bits
- uint, ;; Offset in bits
- uint ;; Dwarf type encoding
- }
+!4 = metadata !{
+ i32, ;; Tag = 36 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
+ ;; (DW_TAG_base_type)
+ metadata, ;; Reference to context
+ metadata, ;; Name (may be "" for anonymous types)
+ metadata, ;; Reference to file where defined (may be NULL)
+ i32, ;; Line number where defined (may be 0)
+ i64, ;; Size in bits
+ i64, ;; Alignment in bits
+ i64, ;; Offset in bits
+ i32, ;; Flags
+ i32 ;; DWARF type encoding
+}
</pre>
+</div>
<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>
+ 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 context
+ 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>
+ one of the following:</p>
+<div class="doc_code">
<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
+DW_ATE_address = 1
+DW_ATE_boolean = 2
+DW_ATE_float = 4
+DW_ATE_signed = 5
+DW_ATE_signed_char = 6
+DW_ATE_unsigned = 7
+DW_ATE_unsigned_char = 8
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="format_derived_type">Derived type descriptors</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<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)
- int, ;; Line number where defined (may be 0)
- uint, ;; Size in bits
- uint, ;; Alignment in bits
- uint, ;; Offset in bits
- { }* ;; Reference to type derived from
- }
+!5 = metadata !{
+ i32, ;; Tag (see below)
+ metadata, ;; Reference to context
+ metadata, ;; Name (may be "" for anonymous types)
+ metadata, ;; Reference to file where defined (may be NULL)
+ i32, ;; Line number where defined (may be 0)
+ i64, ;; Size in bits
+ i64, ;; Alignment in bits
+ i64, ;; Offset in bits
+ i32, ;; Flags to encode attributes, e.g. private
+ metadata, ;; Reference to type derived from
+ metadata, ;; (optional) Name of the Objective C property associated with
+ ;; Objective-C an ivar
+ metadata, ;; (optional) Name of the Objective C property getter selector.
+ metadata, ;; (optional) Name of the Objective C property setter selector.
+ i32 ;; (optional) Objective C property attributes.
+}
</pre>
+</div>
<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>
+tag values:</p>
+<div class="doc_code">
<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
+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>
+</div>
-<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_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_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><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>
+ from the context 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>
+<p>Note that the <tt>void *</tt> type is expressed as a type derived from NULL.
+</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="format_composite_type">Composite type descriptors</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<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)
- int, ;; 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
- }
+!6 = metadata !{
+ i32, ;; Tag (see below)
+ metadata, ;; Reference to context
+ metadata, ;; Name (may be "" for anonymous types)
+ metadata, ;; Reference to file where defined (may be NULL)
+ i32, ;; Line number where defined (may be 0)
+ i64, ;; Size in bits
+ i64, ;; Alignment in bits
+ i64, ;; Offset in bits
+ i32, ;; Flags
+ metadata, ;; Reference to type derived from
+ metadata, ;; Reference to array of member descriptors
+ i32 ;; Runtime languages
+}
</pre>
+</div>
<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>
+are possible tag values:</p>
+<div class="doc_code">
<pre>
- DW_TAG_array_type = 1
- DW_TAG_enumeration_type = 4
- DW_TAG_structure_type = 19
- DW_TAG_union_type = 23
+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 = 21
+DW_TAG_inheritance = 28
</pre>
+</div>
-<p>The members of array types (tag = <tt>DW_TAG_array_type</tt>) are <a
-href="#format_subrange">subrange descriptors</a>, each representing the range of
-subscripts at that level of indexing.</p>
+<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>
+ <a href="#format_enumeration">enumerator descriptors</a>, each representing
+ the definition of enumeration value for the set. All enumeration type
+ descriptors are collected by named metadata <tt>!llvm.dbg.enum</tt>.</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>
+ = <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>
+ determined from the context and line number. The size, alignment and
+ offset are expressed in bits and can be 64 bit values. The alignment is used
+ to round the offset when embedded in
+ a <a href="#format_composite_type">composite type</a> (as an example, to keep
+ float doubles on 64 bit boundaries.) The offset is the bit offset if embedded
+ in a <a href="#format_composite_type">composite type</a>.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="format_subrange">Subrange descriptors</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
- %<a href="#format_subrange">llvm.dbg.subrange.type</a> = type {
- uint, ;; Tag = 33 (DW_TAG_subrange_type)
- uint, ;; Low value
- uint ;; High value
- }
+!42 = metadata !{
+ i32, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
+ i64, ;; Low value
+ i64 ;; High value
+}
</pre>
+</div>
<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>
+ <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 bounds are not included in generated debugging information.
+</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="format_enumeration">Enumerator descriptors</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
- %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> = type {
- uint, ;; Tag = 40 (DW_TAG_enumerator)
- sbyte*, ;; Name
- uint ;; Value
- }
+!6 = metadata !{
+ i32, ;; Tag = 40 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a>
+ ;; (DW_TAG_enumerator)
+ metadata, ;; Name
+ i64 ;; Value
+}
</pre>
+</div>
-<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>
+<p>These descriptors are used to define members of an
+ enumeration <a href="#format_composite_type">composite type</a>, it
+ associates the name to the value.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="format_common_intrinsics">Debugger intrinsic functions</a>
-</div>
+<h4>
+ <a name="format_variables">Local variables</a>
+</h4>
-<div class="doc_text">
-
-<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
-provide debug information at various points in generated code.</p>
+<div>
+<div class="doc_code">
+<pre>
+!7 = metadata !{
+ i32, ;; Tag (see below)
+ metadata, ;; Context
+ metadata, ;; Name
+ metadata, ;; Reference to file where defined
+ i32, ;; 24 bit - Line number where defined
+ ;; 8 bit - Argument number. 1 indicates 1st argument.
+ metadata, ;; Type descriptor
+ i32, ;; flags
+ metadata ;; (optional) Reference to inline location
+}
+</pre>
</div>
-<!-- ======================================================================= -->
-<div class="doc_subsubsection">
- <a name="format_common_stoppoint">llvm.dbg.stoppoint</a>
-</div>
+<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>
-<div class="doc_text">
+<div class="doc_code">
<pre>
- void %<a href="#format_common_stoppoint">llvm.dbg.stoppoint</a>( uint, uint, %<a href="#format_compile_units">llvm.dbg.compile_unit</a>* )
+DW_TAG_auto_variable = 256
+DW_TAG_arg_variable = 257
+DW_TAG_return_variable = 258
</pre>
+</div>
+
+<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>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 si the column number (0 if unknown) and the third argument the source
-compile unit. 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 <a href="#format_common_stoppoint">lvm.dbg.stoppoint</a>.</p>
+<p>The context is either the subprogram or block where the variable is defined.
+ Name the source variable name. Context and line indicate where the
+ variable was defined. Type descriptor defines the declared type of the
+ variable.</p>
</div>
-<!-- ======================================================================= -->
-<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>( %<a href="#format_subprograms">llvm.dbg.subprogram.type</a>* )
-</pre>
+<!-- ======================================================================= -->
+<h3>
+ <a name="format_common_intrinsics">Debugger intrinsic functions</a>
+</h3>
-<p>This intrinsic is used to link the debug information in <tt>%<a
-href="#format_subprograms">llvm.dbg.subprogram</a></tt> to the function. It also
-defines the beginning of the function's declarative region (scope.) The
-intrinsic should be called early in the function after the all the alloca
-instructions.</p>
+<div>
-</div>
+<p>LLVM uses several intrinsic functions (name prefixed with "llvm.dbg") to
+ provide debug information at various points in generated code.</p>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
- <a name="format_common_region_start">llvm.dbg.region.start</a>
-</div>
+<h4>
+ <a name="format_common_declare">llvm.dbg.declare</a>
+</h4>
-<div class="doc_text">
+<div>
<pre>
- void %<a href="#format_common_region_start">llvm.dbg.region.start</a>()
+ void %<a href="#format_common_declare">llvm.dbg.declare</a>(metadata, metadata)
</pre>
-<p>This intrinsic is used to define the beginning of a declarative scope (ex.
-block) for local language elements. It should be paired off with a closing
-<tt>%<a href="#format_common_region_end">llvm.dbg.region.end</a></tt>.</p>
-
+<p>This intrinsic provides information about a local element (e.g., variable). The
+ first argument is metadata holding the alloca for the variable. The
+ second argument is metadata containing a description of the variable.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
- <a name="format_common_region_end">llvm.dbg.region.end</a>
-</div>
+<h4>
+ <a name="format_common_value">llvm.dbg.value</a>
+</h4>
-<div class="doc_text">
+<div>
<pre>
- void %<a href="#format_common_region_end">llvm.dbg.region.end</a>()
+ void %<a href="#format_common_value">llvm.dbg.value</a>(metadata, i64, metadata)
</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>.</p>
-
+<p>This intrinsic provides information when a user source variable is set to a
+ new value. The first argument is the new value (wrapped as metadata). The
+ second argument is the offset in the user source variable where the new value
+ is written. The third argument is metadata containing a description of the
+ user source variable.</p>
</div>
-<!-- ======================================================================= -->
-<div class="doc_subsubsection">
- <a name="format_common_declare">llvm.dbg.declare</a>
</div>
-<div class="doc_text">
+<!-- ======================================================================= -->
+<h3>
+ <a name="format_common_lifetime">Object lifetimes and scoping</a>
+</h3>
+
+<div>
+<p>In many languages, the local variables in functions can have their lifetimes
+ or scopes 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 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>
+
+<p>In order to handle this, the LLVM debug format uses the metadata attached to
+ llvm instructions to encode line number and scoping information. Consider
+ the following C fragment, for example:</p>
+
+<div class="doc_code">
<pre>
- void %<a href="#format_common_declare">llvm.dbg.declare</a>( {} *, ... )
+1. void foo() {
+2. int X = 21;
+3. int Y = 22;
+4. {
+5. int Z = 23;
+6. Z = X;
+7. }
+8. X = Y;
+9. }
</pre>
-
-<p>This intrinsic provides information about a local element (ex. variable.)
-TODO - details.</p>
-
</div>
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="format_common_stoppoints">
- Representing stopping points in the source program
- </a>
-</div>
+<p>Compiled to LLVM, this function would be represented like this:</p>
-<div class="doc_text">
+<div class="doc_code">
+<pre>
+define void @foo() nounwind ssp {
+entry:
+ %X = alloca i32, align 4 ; <i32*> [#uses=4]
+ %Y = alloca i32, align 4 ; <i32*> [#uses=4]
+ %Z = alloca i32, align 4 ; <i32*> [#uses=3]
+ %0 = bitcast i32* %X to {}* ; <{}*> [#uses=1]
+ call void @llvm.dbg.declare(metadata !{i32 * %X}, metadata !0), !dbg !7
+ store i32 21, i32* %X, !dbg !8
+ %1 = bitcast i32* %Y to {}* ; <{}*> [#uses=1]
+ call void @llvm.dbg.declare(metadata !{i32 * %Y}, metadata !9), !dbg !10
+ store i32 22, i32* %Y, !dbg !11
+ %2 = bitcast i32* %Z to {}* ; <{}*> [#uses=1]
+ call void @llvm.dbg.declare(metadata !{i32 * %Z}, metadata !12), !dbg !14
+ store i32 23, i32* %Z, !dbg !15
+ %tmp = load i32* %X, !dbg !16 ; <i32> [#uses=1]
+ %tmp1 = load i32* %Y, !dbg !16 ; <i32> [#uses=1]
+ %add = add nsw i32 %tmp, %tmp1, !dbg !16 ; <i32> [#uses=1]
+ store i32 %add, i32* %Z, !dbg !16
+ %tmp2 = load i32* %Y, !dbg !17 ; <i32> [#uses=1]
+ store i32 %tmp2, i32* %X, !dbg !17
+ ret void, !dbg !18
+}
-<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 <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>
+declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
+
+!0 = metadata !{i32 459008, metadata !1, metadata !"X",
+ metadata !3, i32 2, metadata !6}; [ DW_TAG_auto_variable ]
+!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
+!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo", metadata !"foo",
+ metadata !"foo", metadata !3, i32 1, metadata !4,
+ i1 false, i1 true}; [DW_TAG_subprogram ]
+!3 = metadata !{i32 458769, i32 0, i32 12, metadata !"foo.c",
+ metadata !"/private/tmp", metadata !"clang 1.1", i1 true,
+ i1 false, metadata !"", i32 0}; [DW_TAG_compile_unit ]
+!4 = metadata !{i32 458773, metadata !3, metadata !"", null, i32 0, i64 0, i64 0,
+ i64 0, i32 0, null, metadata !5, i32 0}; [DW_TAG_subroutine_type ]
+!5 = metadata !{null}
+!6 = metadata !{i32 458788, metadata !3, metadata !"int", metadata !3, i32 0,
+ i64 32, i64 32, i64 0, i32 0, i32 5}; [DW_TAG_base_type ]
+!7 = metadata !{i32 2, i32 7, metadata !1, null}
+!8 = metadata !{i32 2, i32 3, metadata !1, null}
+!9 = metadata !{i32 459008, metadata !1, metadata !"Y", metadata !3, i32 3,
+ metadata !6}; [ DW_TAG_auto_variable ]
+!10 = metadata !{i32 3, i32 7, metadata !1, null}
+!11 = metadata !{i32 3, i32 3, metadata !1, null}
+!12 = metadata !{i32 459008, metadata !13, metadata !"Z", metadata !3, i32 5,
+ metadata !6}; [ DW_TAG_auto_variable ]
+!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
+!14 = metadata !{i32 5, i32 9, metadata !13, null}
+!15 = metadata !{i32 5, i32 5, metadata !13, null}
+!16 = metadata !{i32 6, i32 5, metadata !13, null}
+!17 = metadata !{i32 8, i32 3, metadata !1, null}
+!18 = metadata !{i32 9, i32 1, metadata !2, null}
+</pre>
+</div>
-<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, code duplication transformations, or basic-block
-reordering transformations.</p>
+<p>This example illustrates a few important details about LLVM debugging
+ information. In particular, it shows how the <tt>llvm.dbg.declare</tt>
+ intrinsic and location information, which are attached to an instruction,
+ are applied together to allow a debugger to analyze the relationship between
+ statements, variable definitions, and the code used to implement the
+ function.</p>
+<div class="doc_code">
+<pre>
+call void @llvm.dbg.declare(metadata, metadata !0), !dbg !7
+</pre>
</div>
+<p>The first intrinsic
+ <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
+ encodes debugging information for the variable <tt>X</tt>. The metadata
+ <tt>!dbg !7</tt> attached to the intrinsic provides scope information for the
+ variable <tt>X</tt>.</p>
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="format_common_lifetime">Object lifetimes and scoping</a>
+<div class="doc_code">
+<pre>
+!7 = metadata !{i32 2, i32 7, metadata !1, null}
+!1 = metadata !{i32 458763, metadata !2}; [DW_TAG_lexical_block ]
+!2 = metadata !{i32 458798, i32 0, metadata !3, metadata !"foo",
+ metadata !"foo", metadata !"foo", metadata !3, i32 1,
+ metadata !4, i1 false, i1 true}; [DW_TAG_subprogram ]
+</pre>
</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
-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>
+<p>Here <tt>!7</tt> is metadata providing location information. It has four
+ fields: line number, column number, scope, and original scope. The original
+ scope represents inline location if this instruction is inlined inside a
+ caller, and is null otherwise. In this example, scope is encoded by
+ <tt>!1</tt>. <tt>!1</tt> represents a lexical block inside the scope
+ <tt>!2</tt>, where <tt>!2</tt> is a
+ <a href="#format_subprograms">subprogram descriptor</a>. This way the
+ location information attached to the intrinsics indicates that the
+ variable <tt>X</tt> is declared at line number 2 at a function level scope in
+ function <tt>foo</tt>.</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>Now lets take another example.</p>
+<div class="doc_code">
<pre>
-1. void foo() {
-2. int X = ...;
-3. int Y = ...;
-4. {
-5. int Z = ...;
-6. ...
-7. }
-8. ...
-9. }
+call void @llvm.dbg.declare(metadata, metadata !12), !dbg !14
</pre>
+</div>
-<p>Compiled to LLVM, this function would be represented like this:</p>
+<p>The second intrinsic
+ <tt>%<a href="#format_common_declare">llvm.dbg.declare</a></tt>
+ encodes debugging information for variable <tt>Z</tt>. The metadata
+ <tt>!dbg !14</tt> attached to the intrinsic provides scope information for
+ the variable <tt>Z</tt>.</p>
+<div class="doc_code">
<pre>
-void %foo() {
-entry:
- %X = alloca int
- %Y = alloca int
- %Z = alloca int
-
- ...
-
- 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>
-
- 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>
-
- 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>
-
- 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
-}
+!13 = metadata !{i32 458763, metadata !1}; [DW_TAG_lexical_block ]
+!14 = metadata !{i32 5, i32 9, metadata !13, null}
</pre>
+</div>
-<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>
-
-<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 couldchange how name lookup is
-performed.</p>
+<p>Here <tt>!14</tt> indicates that <tt>Z</tt> is declared at line number 5 and
+ column number 9 inside of lexical scope <tt>!13</tt>. The lexical scope
+ itself resides inside of lexical scope <tt>!1</tt> described above.</p>
-</div>
+<p>The scope information attached with each instruction provides a
+ straightforward way to find instructions covered by a scope.</p>
+</div>
+</div>
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="ccxx_frontend">C/C++ front-end specific debug information</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<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>
+ 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>
+ 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>
+ debug information that would best describe those constructs.</p>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="ccxx_compile_units">C/C++ source file information</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
-<p>Given the source files "MySource.cpp" and "MyHeader.h" located in the
-directory "/Users/mine/sources", the following code;</p>
+<p>Given the source files <tt>MySource.cpp</tt> and <tt>MyHeader.h</tt> located
+ in the directory <tt>/Users/mine/sources</tt>, the following code:</p>
+<div class="doc_code">
<pre>
#include "MyHeader.h"
return 0;
}
</pre>
+</div>
-<p>a C/C++ front-end would generate the following descriptors;</p>
+<p>a C/C++ front-end would generate the following descriptors:</p>
+<div class="doc_code">
<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.)
+;; Define the compile unit for the main source file "/Users/mine/sources/MySource.cpp".
;;
-%<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"
+!2 = metadata !{
+ i32 524305, ;; Tag
+ i32 0, ;; Unused
+ i32 4, ;; Language Id
+ metadata !"MySource.cpp",
+ metadata !"/Users/mine/sources",
+ metadata !"4.2.1 (Based on Apple Inc. build 5649) (LLVM build 00)",
+ i1 true, ;; Main Compile Unit
+ i1 false, ;; Optimized compile unit
+ metadata !"", ;; Compiler flags
+ i32 0} ;; Runtime version
;;
-;; Define the compile unit for the source file "/Users/mine/sources/MySource.cpp".
+;; Define the file for the 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 17,
- { }* 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 17,
- { }* 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"
+!1 = metadata !{
+ i32 524329, ;; Tag
+ metadata !"MySource.cpp",
+ metadata !"/Users/mine/sources",
+ metadata !2 ;; Compile unit
+}
;;
-;; Define each of the strings used in the compile units.
+;; Define the file for the file "/Users/mine/sources/Myheader.h"
;;
-%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";
+!3 = metadata !{
+ i32 524329, ;; Tag
+ metadata !"Myheader.h"
+ metadata !"/Users/mine/sources",
+ metadata !2 ;; Compile unit
+}
+
...
</pre>
+</div>
+<p>llvm::Instruction provides easy access to metadata attached with an
+instruction. One can extract line number information encoded in LLVM IR
+using <tt>Instruction::getMetadata()</tt> and
+<tt>DILocation::getLineNumber()</tt>.
+<pre>
+ if (MDNode *N = I->getMetadata("dbg")) { // Here I is an LLVM instruction
+ DILocation Loc(N); // DILocation is in DebugInfo.h
+ unsigned Line = Loc.getLineNumber();
+ StringRef File = Loc.getFilename();
+ StringRef Dir = Loc.getDirectory();
+ }
+</pre>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="ccxx_global_variable">C/C++ global variable information</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
-<p>Given an integer global variable declared as follows;</p>
+<p>Given an integer global variable declared as follows:</p>
+<div class="doc_code">
<pre>
int MyGlobal = 100;
</pre>
+</div>
-<p>a C/C++ front-end would generate the following descriptors;</p>
+<p>a C/C++ front-end would generate the following descriptors:</p>
+<div class="doc_code">
<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.)
+;; List of debug info of globals
;;
-%<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"
+!llvm.dbg.gv = !{!0}
;;
;; 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 52,
- { }* 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),
- { }* 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"
-
+!0 = metadata !{
+ i32 524340, ;; Tag
+ i32 0, ;; Unused
+ metadata !1, ;; Context
+ metadata !"MyGlobal", ;; Name
+ metadata !"MyGlobal", ;; Display Name
+ metadata !"MyGlobal", ;; Linkage Name
+ metadata !3, ;; Compile Unit
+ i32 1, ;; Line Number
+ metadata !4, ;; Type
+ i1 false, ;; Is a local variable
+ i1 true, ;; Is this a definition
+ i32* @MyGlobal ;; The global variable
+}
+
;;
;; 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 36,
- { }* 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"
+!4 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"int", ;; Name
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 32, ;; Size in Bits
+ i64 32, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 5 ;; Encoding
+}
-;;
-;; 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 [4 x sbyte] c"int\00", section "llvm.metadata"
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="ccxx_subprogram">C/C++ function information</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
-<p>Given a function declared as follows;</p>
+<p>Given a function declared as follows:</p>
+<div class="doc_code">
<pre>
int main(int argc, char *argv[]) {
return 0;
}
</pre>
+</div>
-<p>a C/C++ front-end would generate the following descriptors;</p>
+<p>a C/C++ front-end would generate the following descriptors:</p>
+<div class="doc_code">
<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 46,
- { }* 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),
- { }* 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,
- null }, section "llvm.metadata"
-
-;;
-;; Define the name of the subprogram.
-;;
-%str1 = internal constant [5 x sbyte] c"main\00", section "llvm.metadata"
-
+!6 = metadata !{
+ i32 524334, ;; Tag
+ i32 0, ;; Unused
+ metadata !1, ;; Context
+ metadata !"main", ;; Name
+ metadata !"main", ;; Display name
+ metadata !"main", ;; Linkage name
+ metadata !1, ;; File
+ i32 1, ;; Line number
+ metadata !4, ;; Type
+ i1 false, ;; Is local
+ i1 true, ;; Is definition
+ i32 0, ;; Virtuality attribute, e.g. pure virtual function
+ i32 0, ;; Index into virtual table for C++ methods
+ i32 0, ;; Type that holds virtual table.
+ i32 0, ;; Flags
+ i1 false, ;; True if this function is optimized
+ Function *, ;; Pointer to llvm::Function
+ null ;; Function template parameters
+}
;;
;; Define the subprogram itself.
;;
-int %main(int %argc, sbyte** %argv) {
+define i32 @main(i32 %argc, i8** %argv) {
...
}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="ccxx_basic_types">C/C++ basic types</a>
-</div>
-
-<div class="doc_text">
+</h3>
-<p>The following are the basic type descriptors for C/C++ core types;</p>
+<div>
-</div>
+<p>The following are the basic type descriptors for C/C++ core types:</p>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="ccxx_basic_type_bool">bool</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
-%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
- uint 36,
- { }* 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"
+!2 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"bool", ;; Name
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 8, ;; Size in Bits
+ i64 8, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 2 ;; Encoding
+}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="ccxx_basic_char">char</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
-%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
- uint 36,
- { }* 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"
+!2 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"char", ;; Name
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 8, ;; Size in Bits
+ i64 8, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 6 ;; Encoding
+}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="ccxx_basic_unsigned_char">unsigned char</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
-%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
- uint 36,
- { }* 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"
+!2 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"unsigned char",
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 8, ;; Size in Bits
+ i64 8, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 8 ;; Encoding
+}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="ccxx_basic_short">short</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
-%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
- uint 36,
- { }* 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"
+!2 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"short int",
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 16, ;; Size in Bits
+ i64 16, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 5 ;; Encoding
+}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="ccxx_basic_unsigned_short">unsigned short</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
-%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
- uint 36,
- { }* 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"
+!2 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"short unsigned int",
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 16, ;; Size in Bits
+ i64 16, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 7 ;; Encoding
+}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="ccxx_basic_int">int</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
-%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
- uint 36,
- { }* 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>
+!2 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"int", ;; Name
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 32, ;; Size in Bits
+ i64 32, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 5 ;; Encoding
+}
+</pre></div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="ccxx_basic_unsigned_int">unsigned int</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
-%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
- uint 36,
- { }* 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"
+!2 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"unsigned int",
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 32, ;; Size in Bits
+ i64 32, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 7 ;; Encoding
+}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="ccxx_basic_long_long">long long</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
-%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
- uint 36,
- { }* 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"
+!2 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"long long int",
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 64, ;; Size in Bits
+ i64 64, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 5 ;; Encoding
+}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="ccxx_basic_unsigned_long_long">unsigned long long</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
-%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
- uint 36,
- { }* 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"
+!2 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"long long unsigned int",
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 64, ;; Size in Bits
+ i64 64, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 7 ;; Encoding
+}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="ccxx_basic_float">float</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
-%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
- uint 36,
- { }* 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"
+!2 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"float",
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 32, ;; Size in Bits
+ i64 32, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 4 ;; Encoding
+}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsubsection">
+<h4>
<a name="ccxx_basic_double">double</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
+<div class="doc_code">
<pre>
-%<a href="#format_basic_type">llvm.dbg.basictype</a> = internal constant %<a href="#format_basic_type">llvm.dbg.basictype.type</a> {
- uint 36,
- { }* 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"
+!2 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"double",;; Name
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 64, ;; Size in Bits
+ i64 64, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 4 ;; Encoding
+}
</pre>
+</div>
+
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="ccxx_derived_types">C/C++ derived types</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
-<p>Given the following as an example of C/C++ derived type;</p>
+<p>Given the following as an example of C/C++ derived type:</p>
+<div class="doc_code">
<pre>
typedef const int *IntPtr;
</pre>
+</div>
-<p>a C/C++ front-end would generate the following descriptors;</p>
+<p>a C/C++ front-end would generate the following descriptors:</p>
+<div class="doc_code">
<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 22,
- { }* 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"
+!2 = metadata !{
+ i32 524310, ;; Tag
+ metadata !1, ;; Context
+ metadata !"IntPtr", ;; Name
+ metadata !3, ;; File
+ i32 0, ;; Line number
+ i64 0, ;; Size in bits
+ i64 0, ;; Align in bits
+ i64 0, ;; Offset in bits
+ i32 0, ;; Flags
+ metadata !4 ;; Derived From type
+}
;;
;; 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 15,
- { }* 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"
-
+!4 = metadata !{
+ i32 524303, ;; Tag
+ metadata !1, ;; Context
+ metadata !"", ;; Name
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 64, ;; Size in bits
+ i64 64, ;; Align in bits
+ i64 0, ;; Offset in bits
+ i32 0, ;; Flags
+ metadata !5 ;; Derived From type
+}
;;
;; 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 38,
- { }* 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"
-
+!5 = metadata !{
+ i32 524326, ;; Tag
+ metadata !1, ;; Context
+ metadata !"", ;; Name
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 32, ;; Size in bits
+ i64 32, ;; Align in bits
+ i64 0, ;; Offset in bits
+ i32 0, ;; Flags
+ metadata !6 ;; Derived From type
+}
;;
;; 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 36,
- { }* 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"
+!6 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"int", ;; Name
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 32, ;; Size in bits
+ i64 32, ;; Align in bits
+ i64 0, ;; Offset in bits
+ i32 0, ;; Flags
+ 5 ;; Encoding
+}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="ccxx_composite_types">C/C++ struct/union types</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
-<p>Given the following as an example of C/C++ struct type;</p>
+<p>Given the following as an example of C/C++ struct type:</p>
+<div class="doc_code">
<pre>
struct Color {
unsigned Red;
unsigned Blue;
};
</pre>
+</div>
-<p>a C/C++ front-end would generate the following descriptors;</p>
+<p>a C/C++ front-end would generate the following descriptors:</p>
+<div class="doc_code">
<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 36,
- { }* 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"
-
+!5 = metadata !{
+ i32 524324, ;; Tag
+ metadata !1, ;; Context
+ metadata !"unsigned int",
+ metadata !1, ;; File
+ i32 0, ;; Line number
+ i64 32, ;; Size in Bits
+ i64 32, ;; Align in Bits
+ i64 0, ;; Offset in Bits
+ i32 0, ;; Flags
+ i32 7 ;; Encoding
+}
;;
;; 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 19,
- { }* 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"
+!2 = metadata !{
+ i32 524307, ;; Tag
+ metadata !1, ;; Context
+ metadata !"Color", ;; Name
+ metadata !1, ;; Compile unit
+ i32 1, ;; Line number
+ i64 96, ;; Size in bits
+ i64 32, ;; Align in bits
+ i64 0, ;; Offset in bits
+ i32 0, ;; Flags
+ null, ;; Derived From
+ metadata !3, ;; Elements
+ i32 0 ;; Runtime Language
+}
;;
;; 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 13,
- { }* 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"
+!4 = metadata !{
+ i32 524301, ;; Tag
+ metadata !1, ;; Context
+ metadata !"Red", ;; Name
+ metadata !1, ;; File
+ i32 2, ;; Line number
+ i64 32, ;; Size in bits
+ i64 32, ;; Align in bits
+ i64 0, ;; Offset in bits
+ i32 0, ;; Flags
+ metadata !5 ;; Derived From type
+}
;;
;; 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 13,
- { }* 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"
+!6 = metadata !{
+ i32 524301, ;; Tag
+ metadata !1, ;; Context
+ metadata !"Green", ;; Name
+ metadata !1, ;; File
+ i32 3, ;; Line number
+ i64 32, ;; Size in bits
+ i64 32, ;; Align in bits
+ i64 32, ;; Offset in bits
+ i32 0, ;; Flags
+ metadata !5 ;; Derived From type
+}
;;
;; 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 13,
- { }* 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"
+!7 = metadata !{
+ i32 524301, ;; Tag
+ metadata !1, ;; Context
+ metadata !"Blue", ;; Name
+ metadata !1, ;; File
+ i32 4, ;; Line number
+ i64 32, ;; Size in bits
+ i64 32, ;; Align in bits
+ i64 64, ;; Offset in bits
+ i32 0, ;; Flags
+ metadata !5 ;; Derived From type
+}
;;
;; 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"
+!3 = metadata !{metadata !4, metadata !6, metadata !7}
</pre>
+</div>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="ccxx_enumeration_types">C/C++ enumeration types</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
-<p>Given the following as an example of C/C++ enumeration type;</p>
+<p>Given the following as an example of C/C++ enumeration type:</p>
+<div class="doc_code">
<pre>
enum Trees {
Spruce = 100,
Maple = 300
};
</pre>
+</div>
-<p>a C/C++ front-end would generate the following descriptors;</p>
+<p>a C/C++ front-end would generate the following descriptors:</p>
+<div class="doc_code">
<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 4,
- { }* 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"
+!2 = metadata !{
+ i32 524292, ;; Tag
+ metadata !1, ;; Context
+ metadata !"Trees", ;; Name
+ metadata !1, ;; File
+ i32 1, ;; Line number
+ i64 32, ;; Size in bits
+ i64 32, ;; Align in bits
+ i64 0, ;; Offset in bits
+ i32 0, ;; Flags
+ null, ;; Derived From type
+ metadata !3, ;; Elements
+ i32 0 ;; Runtime language
+}
+
+;;
+;; Define the array of enumerators used by composite type Trees.
+;;
+!3 = metadata !{metadata !4, metadata !5, metadata !6}
;;
;; Define Spruce enumerator.
;;
-%<a href="#format_enumeration">llvm.dbg.enumerator1</a> = internal constant %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> {
- uint 40,
- 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"
+!4 = metadata !{i32 524328, metadata !"Spruce", i64 100}
;;
;; Define Oak enumerator.
;;
-%<a href="#format_enumeration">llvm.dbg.enumerator2</a> = internal constant %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> {
- uint 40,
- 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"
+!5 = metadata !{i32 524328, metadata !"Oak", i64 200}
;;
;; Define Maple enumerator.
;;
-%<a href="#format_enumeration">llvm.dbg.enumerator3</a> = internal constant %<a href="#format_enumeration">llvm.dbg.enumerator.type</a> {
- uint 40,
- 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"
+!6 = metadata !{i32 524328, metadata !"Maple", i64 300}
-;;
-;; 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>
+
+</div>
+
+</div>
+
+
+<!-- *********************************************************************** -->
+<h2>
+ <a name="llvmdwarfextension">Debugging information format</a>
+</h2>
+<!-- *********************************************************************** -->
+<div>
+<!-- ======================================================================= -->
+<h3>
+ <a name="objcproperty">Debugging Information Extension for Objective C
+Properties</a></li>
+</h3>
+<div>
+<!-- *********************************************************************** -->
+<h4>
+ <a name="objcpropertyintroduction">Introduction</a>
+</h4>
+<!-- *********************************************************************** -->
+
+<div>
+<p>Objective C provides a simpler way to declare and define accessor methods
+using declared properties. The language provides features to declare a
+property and to let compiler synthesize accessor methods.
+</p>
+
+<p>The debugger lets developer inspect Objective C interfaces and their
+instance variables and class variables. However, the debugger does not know
+anything about the properties defined in Objective C interfaces. The debugger
+consumes information generated by compiler in DWARF format. The format does
+not support encoding of Objective C properties. This proposal describes DWARF
+extensions to encode Objective C properties, which the debugger can use to let
+developers inspect Objective C properties.
+</p>
+
+</div>
+
+
+<!-- *********************************************************************** -->
+<h4>
+ <a name="objcpropertyproposal">Proposal</a>
+</h4>
+<!-- *********************************************************************** -->
+
+<div>
+<p>Objective C properties exist separately from class members. A property
+can be defined only by "setter" and "getter" selectors, and
+be calculated anew on each access. Or a property can just be a direct access
+to some declared ivar. Finally it can have an ivar "automatically
+synthesized" for it by the compiler, in which case the property can be
+referred to in user code directly using the standard C dereference syntax as
+well as through the property "dot" syntax, but there is no entry in
+the @interface declaration corresponding to this ivar.
+</p>
+<p>
+To facilitate debugging, these properties we will add a new DWARF TAG into the
+DW_TAG_structure_type definition for the class to hold the description of a
+given property, and a set of DWARF attributes that provide said description.
+The property tag will also contain the name and declared type of the property.
+</p>
+<p>
+If there is a related ivar, there will also be a DWARF property attribute placed
+in the DW_TAG_member DIE for that ivar referring back to the property TAG for
+that property. And in the case where the compiler synthesizes the ivar directly,
+the compiler is expected to generate a DW_TAG_member for that ivar (with the
+DW_AT_artificial set to 1), whose name will be the name used to access this
+ivar directly in code, and with the property attribute pointing back to the
+property it is backing.
+</p>
+<p>
+The following examples will serve as illustration for our discussion:
+</p>
+
+<div class="doc_code">
+<pre>
+@interface I1 {
+ int n2;
+}
+
+@property int p1;
+@property int p2;
+@end
+
+@implementation I1
+@synthesize p1;
+@synthesize p2 = n2;
+@end
+</pre>
+</div>
+
+<p>
+This produces the following DWARF (this is a "pseudo dwarfdump" output):
+</p>
+<div class="doc_code">
+<pre>
+0x00000100: TAG_structure_type [7] *
+ AT_APPLE_runtime_class( 0x10 )
+ AT_name( "I1" )
+ AT_decl_file( "Objc_Property.m" )
+ AT_decl_line( 3 )
+
+0x00000110 TAG_APPLE_property
+ AT_name ( "p1" )
+ AT_type ( {0x00000150} ( int ) )
+
+0x00000120: TAG_APPLE_property
+ AT_name ( "p2" )
+ AT_type ( {0x00000150} ( int ) )
+
+0x00000130: TAG_member [8]
+ AT_name( "_p1" )
+ AT_APPLE_property ( {0x00000110} "p1" )
+ AT_type( {0x00000150} ( int ) )
+ AT_artificial ( 0x1 )
+
+0x00000140: TAG_member [8]
+ AT_name( "n2" )
+ AT_APPLE_property ( {0x00000120} "p2" )
+ AT_type( {0x00000150} ( int ) )
+
+0x00000150: AT_type( ( int ) )
+</pre>
+</div>
+<p> Note, the current convention is that the name of the ivar for an
+auto-synthesized property is the name of the property from which it derives with
+an underscore prepended, as is shown in the example.
+But we actually don't need to know this convention, since we are given the name
+of the ivar directly.
+</p>
+
+<p>
+Also, it is common practice in ObjC to have different property declarations in
+the @interface and @implementation - e.g. to provide a read-only property in
+the interface,and a read-write interface in the implementation. In that case,
+the compiler should emit whichever property declaration will be in force in the
+current translation unit.
+</p>
+
+<p> Developers can decorate a property with attributes which are encoded using
+DW_AT_APPLE_property_attribute.
+</p>
+
+<div class="doc_code">
+<pre>
+@property (readonly, nonatomic) int pr;
+</pre>
+</div>
+<p>
+Which produces a property tag:
+<p>
+<div class="doc_code">
+<pre>
+TAG_APPLE_property [8]
+ AT_name( "pr" )
+ AT_type ( {0x00000147} (int) )
+ AT_APPLE_property_attribute (DW_APPLE_PROPERTY_readonly, DW_APPLE_PROPERTY_nonatomic)
+</pre>
+</div>
+
+<p> The setter and getter method names are attached to the property using
+DW_AT_APPLE_property_setter and DW_AT_APPLE_property_getter attributes.
+</p>
+<div class="doc_code">
+<pre>
+@interface I1
+@property (setter=myOwnP3Setter:) int p3;
+-(void)myOwnP3Setter:(int)a;
+@end
+
+@implementation I1
+@synthesize p3;
+-(void)myOwnP3Setter:(int)a{ }
+@end
+</pre>
+</div>
+
+<p>
+The DWARF for this would be:
+</p>
+<div class="doc_code">
+<pre>
+0x000003bd: TAG_structure_type [7] *
+ AT_APPLE_runtime_class( 0x10 )
+ AT_name( "I1" )
+ AT_decl_file( "Objc_Property.m" )
+ AT_decl_line( 3 )
+
+0x000003cd TAG_APPLE_property
+ AT_name ( "p3" )
+ AT_APPLE_property_setter ( "myOwnP3Setter:" )
+ AT_type( {0x00000147} ( int ) )
+
+0x000003f3: TAG_member [8]
+ AT_name( "_p3" )
+ AT_type ( {0x00000147} ( int ) )
+ AT_APPLE_property ( {0x000003cd} )
+ AT_artificial ( 0x1 )
+</pre>
+</div>
+
+</div>
+
+<!-- *********************************************************************** -->
+<h4>
+ <a name="objcpropertynewtags">New DWARF Tags</a>
+</h4>
+<!-- *********************************************************************** -->
+
+<div>
+<table border="1" cellspacing="0">
+ <tr>
+ <th width=200 >TAG</th>
+ <th width=200 >Value</th>
+ </tr>
+ <tr>
+ <td width=200 >DW_TAG_APPLE_property</td>
+ <td width=200 >0x4200</td>
+ </tr>
+</table>
+
+</div>
+
+<!-- *********************************************************************** -->
+<h4>
+ <a name="objcpropertynewattributes">New DWARF Attributes</a>
+</h4>
+<!-- *********************************************************************** -->
+
+<div>
+<table border="1" cellspacing="0">
+ <tr>
+ <th width=200 >Attribute</th>
+ <th width=200 >Value</th>
+ <th width=200 >Classes</th>
+ </tr>
+ <tr>
+ <td width=200 >DW_AT_APPLE_property</td>
+ <td width=200 >0x3fed</td>
+ <td width=200 >Reference</td>
+ </tr>
+ <tr>
+ <td width=200 >DW_AT_APPLE_property_getter</td>
+ <td width=200 >0x3fe9</td>
+ <td width=200 >String</td>
+ </tr>
+ <tr>
+ <td width=200 >DW_AT_APPLE_property_setter</td>
+ <td width=200 >0x3fea</td>
+ <td width=200 >String</td>
+ </tr>
+ <tr>
+ <td width=200 >DW_AT_APPLE_property_attribute</td>
+ <td width=200 >0x3feb</td>
+ <td width=200 >Constant</td>
+ </tr>
+</table>
+
+</div>
+
+<!-- *********************************************************************** -->
+<h4>
+ <a name="objcpropertynewconstants">New DWARF Constants</a>
+</h4>
+<!-- *********************************************************************** -->
+
+<div>
+<table border="1" cellspacing="0">
+ <tr>
+ <th width=200 >Name</th>
+ <th width=200 >Value</th>
+ </tr>
+ <tr>
+ <td width=200 >DW_AT_APPLE_PROPERTY_readonly</td>
+ <td width=200 >0x1</td>
+ </tr>
+ <tr>
+ <td width=200 >DW_AT_APPLE_PROPERTY_readwrite</td>
+ <td width=200 >0x2</td>
+ </tr>
+ <tr>
+ <td width=200 >DW_AT_APPLE_PROPERTY_assign</td>
+ <td width=200 >0x4</td>
+ </tr>
+ <tr>
+ <td width=200 >DW_AT_APPLE_PROPERTY_retain</td>
+ <td width=200 >0x8</td>
+ </tr>
+ <tr>
+ <td width=200 >DW_AT_APPLE_PROPERTY_copy</td>
+ <td width=200 >0x10</td>
+ </tr>
+ <tr>
+ <td width=200 >DW_AT_APPLE_PROPERTY_nonatomic</td>
+ <td width=200 >0x20</td>
+ </tr>
+</table>
+
+</div>
+</div>
</div>
<!-- *********************************************************************** -->
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+ <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
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