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++.</p>
+ for C/C++ looks like.</p>
</div>
an LLVM user a relationship between generated code and the original program
source code.</p>
-<p>Currently, debug information is consumed by the DwarfWriter to produce dwarf
+<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>
0x1000.)</p>
<p>The fields of debug descriptors used internally by LLVM
- are restricted to only the simple data types <tt>int</tt>, <tt>uint</tt>,
- <tt>bool</tt>, <tt>float</tt>, <tt>double</tt>, <tt>mdstring</tt> and
- <tt>mdnode</tt>. </p>
+ 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>
!1 = metadata !{
- uint, ;; A tag
+ i32, ;; A tag
...
}
</pre>
</div>
<p><a name="LLVMDebugVersion">The first field of a descriptor is always an
- <tt>uint</tt> containing a tag value identifying the content of the
+ <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
+ with the current debug version (LLVMDebugVersion = 8 << 16 or 0x80000 or
524288.)</a></p>
<p>The details of the various descriptors follow.</p>
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
+ {}* ;; 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>
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
+ i1 ;; isArtificial
+ i1 ;; isOptimized
+ Function *;; Pointer to LLVM function
+ metadata ;; Lists function template parameters
}
</pre>
</div>
<p>These descriptors provide debug information about functions, methods and
subprograms. They provide details such as name, return types and the source
- location where the subprogram is defined.</p>
+ location where the subprogram is defined.
+ All subprogram descriptors are collected by a named metadata
+ <tt>!llvm.dbg.sp</tt>.
+</p>
</div>
<div class="doc_code">
<pre>
!3 = metadata !{
- i32, ;; Tag = 13 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_lexical_block)
- metadata ;; Reference to context descriptor
+ 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>
<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>
+ subprogram. The line number and column numbers are used to dinstinguish
+ two lexical blocks at same depth. </p>
</div>
metadata, ;; Name (may be "" for anonymous types)
metadata, ;; Reference to file where defined (may be NULL)
i32, ;; Line number where defined (may be 0)
- i32, ;; Size in bits
- i32, ;; Alignment in bits
- i32, ;; Offset in bits
- metadata ;; Reference to type derived from
+ i64, ;; Size in bits
+ i64, ;; Alignment in bits
+ i64, ;; Offset in bits
+ metadata, ;; Reference to type derived from
+ metadata, ;; (optional) Name of the Objective C property assoicated 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>
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 <tt>NULL</tt> derived type.</p>
+<p>Note that the <tt>void *</tt> type is expressed as a type derived from NULL.
+</p>
</div>
<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>
+ 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
<div class="doc_code">
<pre>
-%<a href="#format_subrange">llvm.dbg.subrange.type</a> = type {
+!42 = metadata !{
i32, ;; Tag = 33 + <a href="#LLVMDebugVersion">LLVMDebugVersion</a> (DW_TAG_subrange_type)
i64, ;; Low value
i64 ;; High value
<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>
+ > high the array bounds are not included in generated debugging information.
+</p>
</div>
metadata, ;; Context
metadata, ;; Name
metadata, ;; Reference to file where defined
- i32, ;; Line number where defined
+ i32, ;; 24 bit - Line number where defined
+ ;; 8 bit - Argument number. 1 indicates 1st argument.
metadata ;; Type descriptor
}
</pre>
<div class="doc_text">
<pre>
- void %<a href="#format_common_declare">llvm.dbg.declare</a>( { } *, metadata )
+ void %<a href="#format_common_declare">llvm.dbg.declare</a>(metadata, metadata)
</pre>
<p>This intrinsic provides information about a local element (ex. variable.) The
- first argument is the alloca for the variable, cast to a <tt>{ }*</tt>. The
- second argument is
- the <tt>%<a href="#format_variables">llvm.dbg.variable</a></tt> containing
- the description of the variable. </p>
-
+ first argument is metadata holding alloca for the variable. The
+ second argument is metadata containing description of the variable. </p>
</div>
<!-- ======================================================================= -->
<div class="doc_text">
<pre>
- void %<a href="#format_common_value">llvm.dbg.value</a>( metadata, i64, metadata )
+ void %<a href="#format_common_value">llvm.dbg.value</a>(metadata, i64, metadata)
</pre>
<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
- the <tt>%<a href="#format_variables">llvm.dbg.variable</a></tt> containing
- the description of the user source variable. </p>
-
+ is written. The third argument is metadata containing description of the
+ user source variable. </p>
</div>
<!-- ======================================================================= -->
rules.</p>
<p>In order to handle this, the LLVM debug format uses the metadata attached to
- llvm instructions to encode line nuber and scoping information. Consider the
- following C fragment, for example:</p>
+ llvm instructions to encode line number and scoping information. Consider
+ the following C fragment, for example:</p>
<div class="doc_code">
<pre>
%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({ }* %0, metadata !0), !dbg !7
+ %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({ }* %1, metadata !9), !dbg !10
+ %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({ }* %2, metadata !12), !dbg !14
+ %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]
ret void, !dbg !18
}
-declare void @llvm.dbg.declare({ }*, metadata) nounwind readnone
+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 ]
<div class="doc_code">
<pre>
-call void @llvm.dbg.declare({ }* %0, metadata !0), !dbg !7
+call void @llvm.dbg.declare(metadata, metadata !0), !dbg !7
</pre>
</div>
<div class="doc_code">
<pre>
-call void @llvm.dbg.declare({ }* %2, metadata !12), !dbg !14
+call void @llvm.dbg.declare(metadata, metadata !12), !dbg !14
</pre>
</div>
i32 524329, ;; Tag
metadata !"MySource.cpp",
metadata !"/Users/mine/sources",
- metadata !3 ;; Compile unit
+ metadata !2 ;; Compile unit
}
;;
i32 524329, ;; Tag
metadata !"Myheader.h"
metadata !"/Users/mine/sources",
- metadata !3 ;; Compile unit
+ metadata !2 ;; Compile unit
}
...
i32 1, ;; Line number
metadata !4, ;; Type
i1 false, ;; Is local
- i1 true ;; Is definition
+ 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.
src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
- <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
+ <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Last modified: $Date$
</address>
projects / oota-llvm.git / blobdiff