LLVM-DEBUGINFO-ANALYZER(1)
💅 llvm-debuginfo-analyzer 💅
okay so. bestie. this is the manual page for llvm-debuginfo-analyzer, and it's genuinely one of the coolest tools in the LLVM toolbox, no cap. grab a strawberry drink 🍓 and let's go.
Here's literally everything that's in this page, so you can jump around:
- SYNOPSIS
- DESCRIPTION
- OPTIONS
- GENERAL
- ATTRIBUTES
- OUTPUT
- REPORT
- SELECTION
- ELEMENTS
- LINES
- SCOPES
- SYMBOLS
- TYPES
- COMPARE
- WARNING
- INTERNAL
- EXAMPLES
- TEST CASE 1 - GENERAL OPTIONS
- PRINTING MODE
- BASIC DETAILS
- SELECT LOGICAL ELEMENTS
- COMPARISON MODE
- LOGICAL VIEW
- LOGICAL ELEMENTS
- PRINTING MODE
- TEST CASE 2 - ASSEMBLER INSTRUCTIONS
- CodeView - Clang (Windows)
- CodeView - MSVC (Windows)
- DWARF - Clang (Linux)
- DWARF - GCC (Linux)
- TEST CASE 3 - INCORRECT LEXICAL SCOPE FOR TYPEDEF
- CodeView - Clang (Windows)
- CodeView - MSVC (Windows)
- DWARF - Clang (Linux)
- DWARF - GCC (Linux)
- TEST CASE 4 - MISSING NESTED ENUMERATIONS
- CodeView - Clang (Windows)
- CodeView - MSVC (Windows)
- DWARF - Clang (Linux)
- DWARF - GCC (Linux)
- TEST CASE 5 - INCORRECT LEXICAL SCOPE FOR VARIABLE
- CODEVIEW - Clang (Windows)
- CODEVIEW - MSVC (Windows)
- DWARF - Clang (Linux)
- DWARF - GCC (Linux)
- TEST CASE 6 - FULL LOGICAL VIEW
- TEST CASE 1 - GENERAL OPTIONS
- EXIT STATUS
- SEE ALSO
✨ NAME ✨
llvm-debuginfo-analyzer — prints a logical representation of low-level debug information. it's giving "make the scary binary data make sense" energy and we're obsessed 💖
🌸 SYNOPSIS 🌸
llvm-debuginfo-analyzer [options] [filename …]🦋 DESCRIPTION 🦋
llvm-debuginfo-analyzer parses the debug and text sections inside binary object files and prints what it finds as a logical view — that's a human-readable representation that hugs the structure of the original user source code super closely. the object file formats it supports are ELF, Mach-O, PDB and COFF. iconic lineup fr fr 👑
The logical view abstracts away all the complexity that comes with the different low-level representations of debugging information embedded in the object file. llvm-debuginfo-analyzer produces a canonical view of the debug information no matter how it's formatted. same logical view every time regardless of object file format, assuming the debug information correctly represents the same original source code. periodt.
The logical view includes these logical elements: type, scope, symbol and line — the basic software elements used in C/C++. every logical element has a set of attributes, like types, classes, functions, variables, parameters, etc. you can use --attribute to say which attributes get included when printing a logical element. a logical element may also have a kind that describes specific types of elements. for instance, a scope could have a kind value of function, class, namespace.
llvm-debuginfo-analyzer defaults to printing a pre-defined layout of logical elements and attributes. the command line options let you control the printed elements (--print), use a specific layout (--report), match a given pattern (--select, --select-offsets). also, you can limit the output to specified logical elements using (--select-lines, --select-scopes, --select-symbols, --select-types).
llvm-debuginfo-analyzer can also compare a set of logical views (--compare) to find differences and identify possible debug information syntax issues (--warning) in any object file. the way that it just… does both?? 💅
🌈 OPTIONS 🌈
the llvm-debuginfo-analyzer options are separated into several categories, each one tailored to a different purpose:
- GENERAL — standard LLVM options to display help, version, etc.
- ATTRIBUTES — describe how to include different details when printing an element.
- PRINT — specify which elements will be included when printing the view.
- OUTPUT — describe the supported formats when printing the view.
- REPORT — describe the format layouts for view printing.
- SELECTION — allows to use specific criteria or conditions to select which elements to print.
- COMPARE — compare logical views and print missing and/or added elements.
- WARNING — print the warnings detected during the creation of the view.
- INTERNAL — internal analysis of the logical view.
🎀 GENERAL 🎀
this section describes the standard help options — the ones you use to display the usage, version, response files, etc.
-h,--help— show help and usage for this command. (--help-hiddenfor more).--help-list— show help and usage for this command without grouping the options into categories (--help-list-hiddenfor more).--help-hidden— display all available options.--print-all-options— print all option values after command line parsing.--print-options— print non-default options after command line parsing.--version— display the version of the tool.@<FILE>— read command-line options from <FILE>.
if you don't specify any input file, llvm-debuginfo-analyzer defaults to reading a.out and returns an error when no input file is found. 🙈
and if you use - as the input file, llvm-debuginfo-analyzer reads the input from its standard input stream. cute, right?
💖 ATTRIBUTES 💖
the following options enable attributes for the printed elements. the attributes are divided into categories based on the type of data being added, such as: internal offsets in the binary file, location descriptors, register names, user source filenames, additional element transformations, toolchain name, binary file format, etc.
--attribute=<value[,value,...]>— with value being one of the options in the following lists.=all: include all the below attributes.=extended: add low-level attributes.=standard: add standard high-level attributes.
the following attributes describe the most common information for a logical element. they help to identify the lexical scope level; the element visibility across modules (global, local); the toolchain name that produced the binary file.
=global: element referenced across Compile Units.=format: object file format name.=level: lexical scope level (File=0, Compile Unit=1).=local: element referenced only in the Compile Unit.=producer: toolchain identification name.
the following attributes describe files and directory names from the user source code, where the elements are declared or defined; functions with public visibility across modules. these options allow you to map the elements to their user code location, for cross references purposes.
=directories: directories referenced in the debug information.=filename: filename where the element is defined.=files: files referenced in the debug information.=pathname: pathname where the object is defined.=publics: function names that are public.
the following attributes describe additional logical element source transformations, in order to display built-in types (int, bool, etc.); parameters and arguments used during template instantiation; parent name hierarchy; array dimensions information; compiler generated elements and the underlying types associated with the types aliases.
=argument: template parameters replaced by its arguments.=base: base types (int,bool, etc.).=generated: compiler generated elements.=encoded: template arguments encoded in the template name.=qualified: the element type include parents in its name.=reference: element declaration and definition references.=subrange: subrange encoding information for arrays.=typename: template parameters.=underlying: underlying type for type definitions.
the following attributes describe the debug location information for a symbol or scope. it includes the symbol percentage coverage and any gaps within the location layout; ranges determining the code sections attached to a function. when descriptors are used, the target processor registers are displayed.
=coverage: symbol location coverage.=gaps: missing debug location (gaps).=location: symbol debug location.=range: debug location ranges.=register: processor register names.
the following attributes are associated with low level details, such as: offsets in the binary file; discriminators added to the lines of inlined functions in order to distinguish specific instances; debug lines state machine registers; elements discarded by the compiler (inlining) or by the linker optimizations (dead-stripping); system compile units generated by the MS toolchain in PDBs.
=discarded: discarded elements by the linker.=discriminator: discriminators for inlined function instances.=inserted: generated inlined abstract references.=linkage: object file linkage name.=offset: debug information offset.=qualifier: line qualifiers (Newstatement, BasicBlock, etc).=zero: zero line numbers.
the following attribute described specific information for the PE/COFF file format. it includes MS runtime types.
=system: display PDB's MS system elements.
the above attributes are grouped into standard and extended categories that can be enabled.
the standard group contains those attributes that add sufficient information to describe a logical element and that can cover the normal situations while dealing with debug information.
=base=coverage=directories=discriminator=filename=files=format=level=producer=publics=range=reference=zero
the extended group contains those attributes that require a more extended knowledge about debug information. they are intended when a lower level of detail is required.
=argument=discarded=encoded=gaps=generated=global=inserted=linkage=local=location=offset=operation=pathname=qualified=qualifier=register=subrange=system=typename
✨ PRINT ✨
Okay bestie, these next options are literally just "what do we actually show you". The layout you get is decided by --report — and heads up, in the tree layout every element gets its enclosing lexical scopes printed too, even if you never asked for them. Surprise scopes. You're welcome. 🎀
--print=<value[,value,...]>— where value is one of the options from the lists below. 👇=all— Include all the below attributes.
The following ones print the actual elements you asked for; and if you threw in some select conditions (--select), then only the elements that match those get printed. The elements value is the ✨lazy girl special✨ — one word and you get instructions, lines, scopes, symbols and types all at once.
=elements— Instructions, lines, scopes, symbols and types.=instructions— Assembler instructions for code sections.=lines— Source lines referenced in the debug information.=scopes— Lexical blocks (function, class, namespace, etc).=symbols— Symbols (variable, member, parameter, etc).=types— Types (pointer, reference, type alias, etc).
These next ones print the meta tea — the info gathered while all those elements were being created, like: scope contributions to the debug information; a summary of elements created, printed or matched (--select); and any warnings that popped off during view creation. 👑
=sizes— Debug Information scopes contributions.=summary— Summary of elements allocated, selected or printed.=warnings— Warnings detected.
Note: the --print=sizes option is ELF specific. Not everything is invited to that party. 💅
💾 OUTPUT 💾
Now we're talking about how the output gets generated when those logical elements get printed. Sit down, hydrate. 🍓
--output-file=<path>— Redirect the output into a file at <path>, where-means the standard output stream.
llvm-debuginfo-analyzer has this whole concept of a split view. So when you redirect the output from a complex binary format, it gets chopped up into individual files — one per compilation unit, each holding that single unit's logical view output. Iconic, honestly.
--output-folder=<name>— The folder to write a file per compilation unit into, when--output=splitis specified.--output-level=<level>— Only print elements up to the given lexical level value. FYI the input file sits at lexical level zero and a compilation unit is at lexical level one.--output=<value[,value,...]>— where value is one of the options from the list below.=all— Include all the below outputs.=json— Use JSON as the output format (Not implemented).=split— Split the output by Compile Units.=text— Use a free form text output.
--output-sort=<key>— The primary key when ordering elements in the output (default:line). Sorting by logical element kind means you kinda need to be familiar with the element kind selection options (--select-lines,--select-scopes,--select-symbols,--select-types) — those are the ones that describe the different logical element kinds. iykyk. 💅=kind— Sort by element kind.=line— Sort by element line number.=name— Sort by element name.=offset— Sort by element offset.
📊 REPORT 📊
Depending on what task you're running (print, compare, select), there are several layouts supported to show the elements in a way that's actually suitable and easy to understand. Because raw output is giving "wall of text" and nobody asked. 😭
--report=<value[,value,...]>— where value is one of the options from the list below.=all— Include all the below reports.=children— Elements and children are displayed in a tree format.=list— Elements are displayed in a tabular format.=parents— Elements and parents are displayed in a tree format.=view— Elements, parents and children are displayed in a tree format.
The list layout shows logical elements in tabular form, no parent-child relationship whatsoever. Honestly this might be the preferred way to display elements that match specific conditions when you're comparing logical views — it makes spotting differences way easier.
The children, parents and view layouts display elements in a tree format, where the scopes are the nodes and types, symbols, lines and other scopes are the children. The layout shows the lexical scoping relationship between elements, with the binary file as the tree root (level 0) and each compilation unit as a child (level 1). 🌳
- The children layout includes the elements that match any given criteria (
--select) or (--compare) and their children. - The parents layout includes the elements that match any given criteria (
--select) or (--compare) and their parents. - The combined view layout includes the elements that match any given criteria (
--select) or (--compare), plus their parents and children.
Notes, bestie, don't skip these:
- When a selection criteria (
--select) is specified with no report option, the list layout is selected. - The comparison mode always uses the view layout.
🔍 SELECTION 🔍
When you print an element, different data can be included, and it varies (--attribute) — from stuff straight-up attached to the binary file (like offset) all the way to high level details like coverage, lexical scope level, location. And because the printed output can get absolutely massive 💀, there are several selection options that let you print only specific elements.
The pattern matching can ignore case (--select-nocase) and can be extended to use regular expressions (--select-regex). Slay.
🧩 ELEMENTS 🧩
These options let you print elements that match the given <pattern>, offset <value>, or an element <condition>. Very choose-your-own-adventure. 🦋
--select=<pattern>— Print all elements whose name or line number matches the given <pattern>.--select-offsets=<value[,value,...]>— Print all elements whose offset matches the given values. See the--attributeoption.--select-elements=<condition[,condition,...]>— Print all elements that satisfy the given <condition>. Where condition is one of the options below. 👇=discarded— Discarded elements by the linker.=global— Element referenced across Compile Units.=optimized— Optimized inlined abstract references.
--select-nocase— Pattern matching becomes case-insensitive when using--select.--select-regex— Treat any <pattern> strings as regular expressions when selecting with the--selectoption. And if--select-nocaseis specified, the regular expression becomes case-insensitive too. Two-for-one. 💅
If the <pattern> criteria is too general, you can get more selective with an option that targets a particular category of elements: lines (--select-lines), scopes (--select-scopes), symbols (--select-symbols) and types (--select-types). Just know these options require knowledge of the debug information format (DWARF, CodeView, COFF), because the given kind describes a very specific type of element. No vibes-based guessing here. 😭
📍 LINES 📍
These options let you print lines that match the given <kind>. The given criteria describes the debug line state machine registers. Okay nerdy, we love that for you.
--select-lines=<kind[,kind,...]>— where kind is one of the options below.=AlwaysStepInto— marks an always step into.=BasicBlock— Marks a new basic block.=Discriminator— Line that has a discriminator.=EndSequence— Marks the end in the sequence of lines.=EpilogueBegin— Marks the start of a function epilogue.=LineDebug— Lines that correspond to debug lines.=LineAssembler— Lines that correspond to disassembly text.=NeverStepInto— marks a never step into.=NewStatement— Marks a new statement.=PrologueEnd— Marks the end of a function prologue.
🎀 SCOPES 🎀
These options let you print scopes that match the given <kind>.
--select-scopes=<kind[,kind,...]>— where kind is one of the options below.=Aggregate— A class, structure or union.=Array— An array.=Block— A generic block (lexical block or exception block).=CallSite— A call site.=CatchBlock— An exception block.=Class— A class.=CompileUnit— A compile unit.=EntryPoint— A subroutine entry point.=Enumeration— An enumeration.=Function— A function.=FunctionType— A function pointer.=InlinedFunction— An inlined function.=Label— A label.=LexicalBlock— A lexical block.=Namespace— A namespace.=Root— The element representing the main scope.=Structure— A structure.=Subprogram— A subprogram.=Template— A template definition.=TemplateAlias— A template alias.=TemplatePack— A template pack.=TryBlock— An exception try block.=Union— A union.
🏷️ SYMBOLS 🏷️
These options let you print symbols that match the given <kind>.
--select-symbols=<kind[,kind,...]>— where kind is one of the options below.=CallSiteParameter— A call site parameter.=Constant— A constant symbol.=Inheritance— A base class.=Member— A member class.=Parameter— A parameter to function.=Unspecified— Unspecified parameters to function.=Variable— A variable.
🦋 TYPES 🦋
These options let you print types that match the given <kind>.
--select-types=<kind[,kind,...]>— where kind is one of the options below.=Base— a base type, yk, integer, boolean, etc.=Const— the constant specifier.=Enumerator— an enumerator.=Import— an import declaration.=ImportDeclaration— an import declaration (yes bestie, the page literally lists both, so I'm keeping both 💖).=ImportModule— an import module.=Pointer— pointer type.=PointerMember— pointer to member function.=Reference— reference type.=Restrict— restrict specifier.=RvalueReference— R-value reference.=Subrange— array subrange.=TemplateParam— template parameter.=TemplateTemplateParam— template template parameter.=TemplateTypeParam— template type parameter.=TemplateValueParam— template value parameter.=Typedef— type definition.=Unspecified— unspecified type.=Volatile— volatile specifier.
✨ COMPARE ✨
okay so here's the tea 🫖: sometimes printing the elements is just not the move. When you're staring at debug info and what you actually care about is what changed — like the effects of different versions of the same toolchain, or the impact of specific compiler optimizations — printing everything isn't the vibe.
For those cases you're hunting for which elements got added or removed. And because the debug information format is so wildly complicated, a regular diff tool is basically useless for finding those elements — literally impossible when you're dealing with different debug formats. no cap.
llvm-debuginfo-analyzer supports a logical element comparison, so you can find semantic differences between logical views — even ones produced by different toolchain versions, or even totally different debug information formats. slay 💅
When you compare logical views created from different debug formats, the accuracy depends on how closely the debug information represents the user code. For instance, a logical view created from a binary file with DWARF debug information may include more detailed data than a logical view created from a binary file with CodeView/COFF debug information. it's giving "depends on your source material" 🦋
The following options describe the elements to compare.
--compare=<value[,value,...]>— pick what to compare, bestie. With value being one of the options in the following list:=all— include all the below elements.=lines— include lines.=scopes— include scopes.=symbols— include symbols.=types— include types.
llvm-debuginfo-analyzer takes the first binary file on the command line as the reference and the second one as the target. And to get a more descriptive report, the comparison is done twice — the reference and target views get swapped, so you get both those missing elements from the target view and those added elements to the reference view. double the report, double the fun 🎀
See --report options on how to describe the comparison reports.
🚨 WARNING 🚨
When reading the input object files, llvm-debuginfo-analyzer can detect issues in the raw debug information. These may not be considered fatal to the purpose of printing a logical view, but they can give an indication about the quality and potentially expose issues with the generated debug information. so like… not a crisis, but also 👀
The following options describe the warnings to be recorded for later printing, if they are requested by --print.
--warning=<value[,value,...]>— with value being one of the options in the following list:=all— include all the below warnings.
The following options collect additional information during the creation of the logical view, to include invalid coverage values and locations for symbols; invalid code ranges; lines that are zero.
=coverages— invalid symbol coverages values.=lines— debug lines that are zero.=locations— invalid symbol locations.=ranges— invalid code ranges.
🔍 INTERNAL 🔍
For a better understanding of the logical view, you might need access to more detailed internal information. That kind of data helps identify debug information that got processed, or incorrect logical element management. Typically these kind of options are available only in debug builds — but not here, bestie 😭
llvm-debuginfo-analyzer supports these advanced options in both release and debug builds — with the exception of the unique ID, which is generated only in debug builds.
--internal=<value[,value,...]>— with value being one of the options in the following list:=all— include all the below options.
The following options allow to check the integrity of the logical view; collect the debug tags that are processed or not implemented; ignore the logical element line number, to facilitate the logical view comparison when using external comparison tools; print the command line options used to invoke llvm-debuginfo-analyzer.
=id— print unique element ID.=cmdline— print command line.=integrity— check elements integrity.=none— ignore element line number.=tag— debug information tags.
📝 Note: For ELF format, the collected tags represent the debug tags that are not processed. For PE/COFF format, they represent the tags that are processed. yes, it's backwards, no, I don't make the rules 💀
🌈 EXAMPLES 🌈
This section includes some real binary files to show how to use llvm-debuginfo-analyzer to print a logical view and to diagnose possible debug information issues. real ones, fr fr 🫶
🧪 TEST CASE 1 - GENERAL OPTIONS
The below example is used to show different output generated by llvm-debuginfo-analyzer. We compiled the example for an X86 ELF target with Clang (-O0 -g):
1 using INTPTR = const int *;
2 int foo(INTPTR ParamPtr, unsigned ParamUnsigned, bool ParamBool) {
3 if (ParamBool) {
4 typedef int INTEGER;
5 const INTEGER CONSTANT = 7;
6 return CONSTANT;
7 }
8 return ParamUnsigned;
9 }🎨 PRINTING MODE
In this mode llvm-debuginfo-analyzer prints the logical view — or portions of it — based on criteria patterns (including regular expressions) to select the kind of logical elements to be included in the output. pick your faves 💅
🔎 BASIC DETAILS
The following command prints basic details for all the logical elements sorted by the debug information internal offset; it includes its lexical level and debug info format.
llvm-debuginfo-analyzer --attribute=level,format
--output-sort=offset
--print=scopes,symbols,types,lines,instructions
test-dwarf-clang.oor
llvm-debuginfo-analyzer --attribute=level,format
--output-sort=offset
--print=elements
test-dwarf-clang.oEach row represents an element that is present within the debug information. The first column represents the scope level, followed by the associated line number (if any), and finally the description of the element.
Logical View:
[000] {File} 'test-dwarf-clang.o' -> elf64-x86-64
[001] {CompileUnit} 'test.cpp'
[002] 2 {Function} extern not_inlined 'foo' -> 'int'
[003] 2 {Parameter} 'ParamPtr' -> 'INTPTR'
[003] 2 {Parameter} 'ParamUnsigned' -> 'unsigned int'
[003] 2 {Parameter} 'ParamBool' -> 'bool'
[003] {Block}
[004] 5 {Variable} 'CONSTANT' -> 'const INTEGER'
[004] 5 {Line}
[004] {Code} 'movl $0x7, -0x1c(%rbp)'
[004] 6 {Line}
[004] {Code} 'movl $0x7, -0x4(%rbp)'
[004] {Code} 'jmp 0x6'
[004] 8 {Line}
[004] {Code} 'movl -0x14(%rbp), %eax'
[003] 4 {TypeAlias} 'INTEGER' -> 'int'
[003] 2 {Line}
[003] {Code} 'pushq %rbp'
[003] {Code} 'movq %rsp, %rbp'
[003] {Code} 'movb %dl, %al'
[003] {Code} 'movq %rdi, -0x10(%rbp)'
[003] {Code} 'movl %esi, -0x14(%rbp)'
[003] {Code} 'andb $0x1, %al'
[003] {Code} 'movb %al, -0x15(%rbp)'
[003] 3 {Line}
[003] {Code} 'testb $0x1, -0x15(%rbp)'
[003] {Code} 'je 0x13'
[003] 8 {Line}
[003] {Code} 'movl %eax, -0x4(%rbp)'
[003] 9 {Line}
[003] {Code} 'movl -0x4(%rbp), %eax'
[003] {Code} 'popq %rbp'
[003] {Code} 'retq'
[003] 9 {Line}
[002] 1 {TypeAlias} 'INTPTR' -> '* const int'On closer inspection, we can see what could be a potential debug issue:
[003] {Block}
[003] 4 {TypeAlias} 'INTEGER' -> 'int'The ‘INTEGER’ definition is at level [003], the same lexical scope as the anonymous {Block} (‘true’ branch for the ‘if’ statement) — whereas in the original source code the typedef statement is clearly inside that block, so the ‘INTEGER’ definition should also be at level [004] inside the block. caught in 4k 📸
🎯 SELECT LOGICAL ELEMENTS
The following prints all instructions, symbols and types that contain ‘inte’ or ‘movl’ in their names or types, using a tab layout and given the number of matches.
llvm-debuginfo-analyzer --attribute=level
--select-nocase --select-regex
--select=INTe --select=movl
--report=list
--print=symbols,types,instructions,summary
test-dwarf-clang.oLogical View:
[000] {File} 'test-dwarf-clang.o'
[001] {CompileUnit} 'test.cpp'
[003] {Code} 'movl $0x7, -0x1c(%rbp)'
[003] {Code} 'movl $0x7, -0x4(%rbp)'
[003] {Code} 'movl %eax, -0x4(%rbp)'
[003] {Code} 'movl %esi, -0x14(%rbp)'
[003] {Code} 'movl -0x14(%rbp), %eax'
[003] {Code} 'movl -0x4(%rbp), %eax'
[003] 4 {TypeAlias} 'INTEGER' -> 'int'
[004] 5 {Variable} 'CONSTANT' -> 'const INTEGER'
-----------------------------
Element Total Found
-----------------------------
Scopes 3 0
Symbols 4 1
Types 2 1
Lines 17 6
-----------------------------
Total 26 8💅 COMPARISON MODE 💅
okay so in this mode llvm-debuginfo-analyzer compares logical views and drops a report of all the logical elements that are missing or added. and bestie, this is a very powerful aid in finding semantic differences in the debug information produced by different toolchain versions or even completely different toolchains altogether (For example a compiler producing DWARF can be directly compared against a completely different compiler that produces CodeView). 🦋
Given the previous example we found the above debug information issue (related to the previous invalid scope location for the typedef int INTEGER) by comparing against another compiler.
Using GCC to generate test-dwarf-gcc.o, we can apply a selection pattern with the printing mode to obtain the following logical view output.
llvm-debuginfo-analyzer --attribute=level
--select-regex --select-nocase --select=INTe
--report=list
--print=symbols,types
test-dwarf-clang.o test-dwarf-gcc.o
Logical View:
[000] {File} 'test-dwarf-clang.o'
[001] {CompileUnit} 'test.cpp'
[003] 4 {TypeAlias} 'INTEGER' -> 'int'
[004] 5 {Variable} 'CONSTANT' -> 'const INTEGER'
Logical View:
[000] {File} 'test-dwarf-gcc.o'
[001] {CompileUnit} 'test.cpp'
[004] 4 {TypeAlias} 'INTEGER' -> 'int'
[004] 5 {Variable} 'CONSTANT' -> 'const INTEGER'The output shows that both objects contain the same elements. But the typedef INTEGER is located at different scope level. The GCC generated object, shows 4, which is the correct value. 😌
Note that there is no requirement that GCC must produce identical or similar DWARF to Clang to allow the comparison. We're only comparing the semantics. The same case when comparing CodeView debug information generated by MSVC and Clang.
There are 2 comparison methods: logical view and logical elements.
🔍 LOGICAL VIEW 🔍
It compares the logical view as a whole unit; for a match, each compared logical element must have the same parents and children. no shortcuts, no vibes-only matching. 🌸
Using the llvm-debuginfo-analyzer comparison functionality, that issue can be seen in a more global context, that can include the logical view.
The output shows in view form the missing (-), added (+) elements, giving more context by swapping the reference and target object files.
llvm-debuginfo-analyzer --attribute=level
--compare=types
--report=view
--print=symbols,types
test-dwarf-clang.o test-dwarf-gcc.o
Reference: 'test-dwarf-clang.o'
Target: 'test-dwarf-gcc.o'
Logical View:
[000] {File} 'test-dwarf-clang.o'
[001] {CompileUnit} 'test.cpp'
[002] 1 {TypeAlias} 'INTPTR' -> '* const int'
[002] 2 {Function} extern not_inlined 'foo' -> 'int'
[003] {Block}
[004] 5 {Variable} 'CONSTANT' -> 'const INTEGER'
+[004] 4 {TypeAlias} 'INTEGER' -> 'int'
[003] 2 {Parameter} 'ParamBool' -> 'bool'
[003] 2 {Parameter} 'ParamPtr' -> 'INTPTR'
[003] 2 {Parameter} 'ParamUnsigned' -> 'unsigned int'
-[003] 4 {TypeAlias} 'INTEGER' -> 'int'The output shows the merging view path (reference and target) with the missing and added elements.
🧮 LOGICAL ELEMENTS 🧮
It compares individual logical elements without considering if their parents are the same. For both comparison methods, the equal criteria includes the name, source code location, type, lexical scope level. 🫶
llvm-debuginfo-analyzer --attribute=level
--compare=types
--report=list
--print=symbols,types,summary
test-dwarf-clang.o test-dwarf-gcc.o
Reference: 'test-dwarf-clang.o'
Target: 'test-dwarf-gcc.o'
(1) Missing Types:
-[003] 4 {TypeAlias} 'INTEGER' -> 'int'
(1) Added Types:
+[004] 4 {TypeAlias} 'INTEGER' -> 'int'
----------------------------------------
Element Expected Missing Added
----------------------------------------
Scopes 4 0 0
Symbols 0 0 0
Types 2 1 1
Lines 0 0 0
----------------------------------------
Total 6 1 1Changing the Reference and Target order:
llvm-debuginfo-analyzer --attribute=level
--compare=types
--report=list
--print=symbols,types,summary
test-dwarf-gcc.o test-dwarf-clang.o
Reference: 'test-dwarf-gcc.o'
Target: 'test-dwarf-clang.o'
(1) Missing Types:
-[004] 4 {TypeAlias} 'INTEGER' -> 'int'
(1) Added Types:
+[003] 4 {TypeAlias} 'INTEGER' -> 'int'
----------------------------------------
Element Expected Missing Added
----------------------------------------
Scopes 4 0 0
Symbols 0 0 0
Types 2 1 1
Lines 0 0 0
----------------------------------------
Total 6 1 1As the Reference and Target are switched, the Added Types from the first case now are listed as Missing Types. iconic symmetry, honestly. ✨
🌈 TEST CASE 2 - ASSEMBLER INSTRUCTIONS 🌈
The below example is used to show different output generated by llvm-debuginfo-analyzer. We compiled the example for an X86 Codeview and ELF targets with recent versions of Clang, GCC and MSVC (-O0 -g) for Windows and Linux.
1 extern int printf(const char * format, ... );
2
3 int main()
4 {
5 printf("Hello, World\n");
6 return 0;
7 }These are the logical views that llvm-debuginfo-analyzer generates for 3 different compilers (MSVC, Clang and GCC), emitting different debug information formats (CodeView, DWARF) on Windows and Linux. 💀 (three compilers, one tiny hello world, zero chill)
llvm-debuginfo-analyzer --attribute=level,format,producer
--print=lines,instructions
hello-world-codeview-clang.o
hello-world-codeview-msvc.o
hello-world-dwarf-clang.o
hello-world-dwarf-gcc.oCodeView - Clang (Windows)
Logical View:
[000] {File} 'hello-world-codeview-clang.o' -> COFF-x86-64
[001] {CompileUnit} 'hello-world.cpp'
[002] {Producer} 'clang version 14.0.0'
[002] {Function} extern not_inlined 'main' -> 'int'
[003] 4 {Line}
[003] {Code} 'subq $0x28, %rsp'
[003] {Code} 'movl $0x0, 0x24(%rsp)'
[003] 5 {Line}
[003] {Code} 'leaq (%rip), %rcx'
[003] {Code} 'callq 0x0'
[003] 6 {Line}
[003] {Code} 'xorl %eax, %eax'
[003] {Code} 'addq $0x28, %rsp'
[003] {Code} 'retq'CodeView - MSVC (Windows)
Logical View:
[000] {File} 'hello-world-codeview-msvc.o' -> COFF-i386
[001] {CompileUnit} 'hello-world.cpp'
[002] {Producer} 'Microsoft (R) Optimizing Compiler'
[002] {Function} extern not_inlined 'main' -> 'int'
[003] 4 {Line}
[003] {Code} 'pushl %ebp'
[003] {Code} 'movl %esp, %ebp'
[003] 5 {Line}
[003] {Code} 'pushl $0x0'
[003] {Code} 'calll 0x0'
[003] {Code} 'addl $0x4, %esp'
[003] 6 {Line}
[003] {Code} 'xorl %eax, %eax'
[003] 7 {Line}
[003] {Code} 'popl %ebp'
[003] {Code} 'retl'DWARF - Clang (Linux)
Logical View:
[000] {File} 'hello-world-dwarf-clang.o' -> elf64-x86-64
[001] {CompileUnit} 'hello-world.cpp'
[002] {Producer} 'clang version 14.0.0'
[002] 3 {Function} extern not_inlined 'main' -> 'int'
[003] 4 {Line}
[003] {Code} 'pushq %rbp'
[003] {Code} 'movq %rsp, %rbp'
[003] {Code} 'subq $0x10, %rsp'
[003] {Code} 'movl $0x0, -0x4(%rbp)'
[003] 5 {Line}
[003] {Code} 'movabsq $0x0, %rdi'
[003] {Code} 'movb $0x0, %al'
[003] {Code} 'callq 0x0'
[003] 6 {Line}
[003] {Code} 'xorl %eax, %eax'
[003] {Code} 'addq $0x10, %rsp'
[003] {Code} 'popq %rbp'
[003] {Code} 'retq'
[003] 6 {Line}DWARF - GCC (Linux)
Logical View:
[000] {File} 'hello-world-dwarf-gcc.o' -> elf64-x86-64
[001] {CompileUnit} 'hello-world.cpp'
[002] {Producer} 'GNU C++14 9.3.0'
[002] 3 {Function} extern not_inlined 'main' -> 'int'
[003] 4 {Line}
[003] {Code} 'endbr64'
[003] {Code} 'pushq %rbp'
[003] {Code} 'movq %rsp, %rbp'
[003] 5 {Line}
[003] {Code} 'leaq (%rip), %rdi'
[003] {Code} 'movl $0x0, %eax'
[003] {Code} 'callq 0x0'
[003] 6 {Line}
[003] {Code} 'movl $0x0, %eax'
[003] 7 {Line}
[003] {Code} 'popq %rbp'
[003] {Code} 'retq'
[003] 7 {Line}The logical views shows the intermixed lines and assembler instructions, allowing to compare the code generated by the different toolchains. 🎀
🧚 TEST CASE 3 - INCORRECT LEXICAL SCOPE FOR TYPEDEF 🧚
The below example is used to show different output generated by llvm-debuginfo-analyzer. We compiled the example for an X86 Codeview and ELF targets with recent versions of Clang, GCC and MSVC (-O0 -g).
1 int bar(float Input) { return (int)Input; }
2
3 unsigned foo(char Param) {
4 typedef int INT; // ** Definition for INT **
5 INT Value = Param;
6 {
7 typedef float FLOAT; // ** Definition for FLOAT **
8 {
9 FLOAT Added = Value + Param;
10 Value = bar(Added);
11 }
12 }
13 return Value + Param;
14 }okay so this lil test is here to show off a scope issue that lives rent-free in the Clang compiler: PR44884 (Bugs LLVM) / PR44229 (GitHub LLVM). fr fr, it's a whole thing.
Lines 4 and 7 are holding 2 typedefs, defined at completely different lexical scopes:
4 typedef int INT;
7 typedef float FLOAT;And here are the logical views that llvm-debuginfo-analyzer generates for 3 different compilers (MSVC, Clang and GCC), emitting different debug information formats (CodeView, DWARF) on different platforms. vibe check incoming ✨
llvm-debuginfo-analyzer --attribute=level,format,producer
--print=symbols,types,lines
--output-sort=kind
pr-44884-codeview-clang.o
pr-44884-codeview-msvc.o
pr-44884-dwarf-clang.o
pr-44884-dwarf-gcc.o💅 CodeView - Clang (Windows)
Logical View:
[000] {File} 'pr-44884-codeview-clang.o' -> COFF-x86-64
[001] {CompileUnit} 'pr-44884.cpp'
[002] {Producer} 'clang version 14.0.0'
[002] {Function} extern not_inlined 'bar' -> 'int'
[003] {Parameter} 'Input' -> 'float'
[003] 1 {Line}
[002] {Function} extern not_inlined 'foo' -> 'unsigned'
[003] {Block}
[004] {Variable} 'Added' -> 'float'
[004] 9 {Line}
[004] 10 {Line}
[003] {Parameter} 'Param' -> 'char'
[003] {TypeAlias} 'FLOAT' -> 'float'
[003] {TypeAlias} 'INT' -> 'int'
[003] {Variable} 'Value' -> 'int'
[003] 3 {Line}
[003] 5 {Line}
[003] 13 {Line}🎀 CodeView - MSVC (Windows)
Logical View:
[000] {File} 'pr-44884-codeview-msvc.o' -> COFF-i386
[001] {CompileUnit} 'pr-44884.cpp'
[002] {Producer} 'Microsoft (R) Optimizing Compiler'
[002] {Function} extern not_inlined 'bar' -> 'int'
[003] {Variable} 'Input' -> 'float'
[003] 1 {Line}
[002] {Function} extern not_inlined 'foo' -> 'unsigned'
[003] {Block}
[004] {Block}
[005] {Variable} 'Added' -> 'float'
[004] {TypeAlias} 'FLOAT' -> 'float'
[004] 9 {Line}
[004] 10 {Line}
[003] {TypeAlias} 'INT' -> 'int'
[003] {Variable} 'Param' -> 'char'
[003] {Variable} 'Value' -> 'int'
[003] 3 {Line}
[003] 5 {Line}
[003] 13 {Line}
[003] 14 {Line}🦋 DWARF - Clang (Linux)
Logical View:
[000] {File} 'pr-44884-dwarf-clang.o' -> elf64-x86-64
[001] {CompileUnit} 'pr-44884.cpp'
[002] {Producer} 'clang version 14.0.0'
[002] 1 {Function} extern not_inlined 'bar' -> 'int'
[003] 1 {Parameter} 'Input' -> 'float'
[003] 1 {Line}
[003] 1 {Line}
[003] 1 {Line}
[002] 3 {Function} extern not_inlined 'foo' -> 'unsigned int'
[003] {Block}
[004] 9 {Variable} 'Added' -> 'FLOAT'
[004] 9 {Line}
[004] 9 {Line}
[004] 9 {Line}
[004] 9 {Line}
[004] 9 {Line}
[004] 10 {Line}
[004] 10 {Line}
[004] 10 {Line}
[004] 13 {Line}
[003] 3 {Parameter} 'Param' -> 'char'
[003] 7 {TypeAlias} 'FLOAT' -> 'float'
[003] 4 {TypeAlias} 'INT' -> 'int'
[003] 5 {Variable} 'Value' -> 'INT'
[003] 3 {Line}
[003] 5 {Line}
[003] 5 {Line}
[003] 13 {Line}
[003] 13 {Line}
[003] 13 {Line}
[003] 13 {Line}🌈 DWARF - GCC (Linux)
Logical View:
[000] {File} 'pr-44884-dwarf-gcc.o' -> elf32-littlearm
[001] {CompileUnit} 'pr-44884.cpp'
[002] {Producer} 'GNU C++14 10.2.1 20201103'
[002] 1 {Function} extern not_inlined 'bar' -> 'int'
[003] 1 {Parameter} 'Input' -> 'float'
[003] 1 {Line}
[003] 1 {Line}
[003] 1 {Line}
[002] 3 {Function} extern not_inlined 'foo' -> 'unsigned int'
[003] {Block}
[004] {Block}
[005] 9 {Variable} 'Added' -> 'FLOAT'
[005] 9 {Line}
[005] 9 {Line}
[005] 9 {Line}
[005] 10 {Line}
[005] 13 {Line}
[004] 7 {TypeAlias} 'FLOAT' -> 'float'
[003] 3 {Parameter} 'Param' -> 'char'
[003] 4 {TypeAlias} 'INT' -> 'int'
[003] 5 {Variable} 'Value' -> 'INT'
[003] 3 {Line}
[003] 5 {Line}
[003] 13 {Line}
[003] 14 {Line}
[003] 14 {Line}so looking at all those views, we can see that the Clang compiler emits both typedefs at the same lexical scope (3), which is wrong. GCC and MSVC emit the correct lexical scope for both typedefs. the more you know 💫
Now using the llvm-debuginfo-analyzer selection facilities, we can produce a simple tabular output showing just the logical types that are Typedef. obsessed with how clean this is
llvm-debuginfo-analyzer --attribute=level,format
--output-sort=name
--select-types=Typedef
--report=list
--print=types
pr-44884-*.o
Logical View:
[000] {File} 'pr-44884-codeview-clang.o' -> COFF-x86-64
[001] {CompileUnit} 'pr_44884.cpp'
[003] {TypeAlias} 'FLOAT' -> 'float'
[003] {TypeAlias} 'INT' -> 'int'
Logical View:
[000] {File} 'pr-44884-codeview-msvc.o' -> COFF-i386
[001] {CompileUnit} 'pr_44884.cpp'
[004] {TypeAlias} 'FLOAT' -> 'float'
[003] {TypeAlias} 'INT' -> 'int'
Logical View:
[000] {File} 'pr-44884-dwarf-clang.o' -> elf64-x86-64
[001] {CompileUnit} 'pr_44884.cpp'
[003] 7 {TypeAlias} 'FLOAT' -> 'float'
[003] 4 {TypeAlias} 'INT' -> 'int'
Logical View:
[000] {File} 'pr-44884-dwarf-gcc.o' -> elf32-littlearm
[001] {CompileUnit} 'pr_44884.cpp'
[004] 7 {TypeAlias} 'FLOAT' -> 'float'
[003] 4 {TypeAlias} 'INT' -> 'int'It also shows, that the CodeView debug information does not generate source code line numbers for the those logical types. The logical view is sorted by the types name. noted ✍️
🦋 TEST CASE 4 - MISSING NESTED ENUMERATIONS 🦋
bestie the below example is used to show different output generated by llvm-debuginfo-analyzer. We compiled the example for an X86 Codeview and ELF targets with recent versions of Clang, GCC and MSVC (-O0 -g).
1 struct Struct {
2 union Union {
3 enum NestedEnum { RED, BLUE };
4 };
5 Union U;
6 };
7
8 Struct S;
9 int test() {
10 return S.U.BLUE;
11 }This test is used to illustrate a scope issue found in the Clang compiler: PR46466 (Bugs LLVM) / PR45811 (GitHub LLVM). another one 😭 iconic of Clang tbh
These are the logical views that llvm-debuginfo-analyzer generates for 3 different compilers (MSVC, Clang and GCC), emitting different debug information formats (CodeView, DWARF) on different platforms.
llvm-debuginfo-analyzer --attribute=level,format,producer
--output-sort=name
--print=symbols,types
pr-46466-codeview-clang.o
pr-46466-codeview-msvc.o
pr-46466-dwarf-clang.o
pr-46466-dwarf-gcc.o💅 CodeView - Clang (Windows)
Logical View:
[000] {File} 'pr-46466-codeview-clang.o' -> COFF-x86-64
[001] {CompileUnit} 'pr-46466.cpp'
[002] {Producer} 'clang version 14.0.0'
[002] {Variable} extern 'S' -> 'Struct'
[002] 1 {Struct} 'Struct'
[003] {Member} public 'U' -> 'Union'
[003] 2 {Union} 'Union'
[004] 3 {Enumeration} 'NestedEnum' -> 'int'
[005] {Enumerator} 'BLUE' = '0x1'
[005] {Enumerator} 'RED' = '0x0'🎀 CodeView - MSVC (Windows)
Logical View:
[000] {File} 'pr-46466-codeview-msvc.o' -> COFF-i386
[001] {CompileUnit} 'pr-46466.cpp'
[002] {Producer} 'Microsoft (R) Optimizing Compiler'
[002] {Variable} extern 'S' -> 'Struct'
[002] 1 {Struct} 'Struct'
[003] {Member} public 'U' -> 'Union'
[003] 2 {Union} 'Union'
[004] 3 {Enumeration} 'NestedEnum' -> 'int'
[005] {Enumerator} 'BLUE' = '0x1'
[005] {Enumerator} 'RED' = '0x0'🦋 DWARF - Clang (Linux)
Logical View:
[000] {File} 'pr-46466-dwarf-clang.o' -> elf64-x86-64
[001] {CompileUnit} 'pr-46466.cpp'
[002] {Producer} 'clang version 14.0.0'
[002] 8 {Variable} extern 'S' -> 'Struct'
[002] 1 {Struct} 'Struct'
[003] 5 {Member} public 'U' -> 'Union'🌈 DWARF - GCC (Linux)
Logical View:
[000] {File} 'pr-46466-dwarf-gcc.o' -> elf64-x86-64
[001] {CompileUnit} 'pr-46466.cpp' [001] {CompileUnit} 'pr-46466.cpp'
[002] {Producer} 'GNU C++14 9.3.0'
[002] 8 {Variable} extern 'S' -> 'Struct'
[002] 1 {Struct} 'Struct'
[003] 5 {Member} public 'U' -> 'Union'
[003] 2 {Union} 'Union'
[004] 3 {Enumeration} 'NestedEnum' -> 'unsigned int'
[005] {Enumerator} 'BLUE' = '0x1'
[005] {Enumerator} 'RED' = '0x0'So bestie, looking at those logical views we just scrolled past 👀 — the DWARF debug info that the Clang compiler spits out is literally missing any references to the enumerators RED and BLUE. Like, they're just not there. But the DWARF that GCC makes, and the CodeView that Clang and MSVC make? They DO include those references. Periodt.
Now here's where it gets fun 💅 — using llvm-debuginfo-analyzer's selection facilities, we can cook up a logical view showing just the logical types that are Enumerator plus all their parents. And this logical view is sorted by the type's name. Slay.
llvm-debuginfo-analyzer --attribute=format,level
--output-sort=name
--select-types=Enumerator
--report=parents
--print=types
pr-46466-*.o
Logical View:
[000] {File} 'pr-46466-codeview-clang.o' -> COFF-x86-64
[001] {CompileUnit} 'pr-46466.cpp'
[002] 1 {Struct} 'Struct'
[003] 2 {Union} 'Union'
[004] 3 {Enumeration} 'NestedEnum' -> 'int'
[005] {Enumerator} 'BLUE' = '0x1'
[005] {Enumerator} 'RED' = '0x0'
Logical View:
[000] {File} 'pr-46466-codeview-msvc.o' -> COFF-i386
[001] {CompileUnit} 'pr-46466.cpp'
[002] 1 {Struct} 'Struct'
[003] 2 {Union} 'Union'
[004] 3 {Enumeration} 'NestedEnum' -> 'int'
[005] {Enumerator} 'BLUE' = '0x1'
[005] {Enumerator} 'RED' = '0x0'
Logical View:
[000] {File} 'pr-46466-dwarf-clang.o' -> elf64-x86-64
[001] {CompileUnit} 'pr-46466.cpp'
Logical View:
[000] {File} 'pr-46466-dwarf-gcc.o' -> elf64-x86-64
[001] {CompileUnit} 'pr-46466.cpp'
[002] 1 {Struct} 'Struct'
[003] 2 {Union} 'Union'
[004] 3 {Enumeration} 'NestedEnum' -> 'unsigned int'
[005] {Enumerator} 'BLUE' = '0x1'
[005] {Enumerator} 'RED' = '0x0'See how the DWARF-from-Clang one is just giving nothing? Not one enumerator. It's giving ghosted. 🫥 The others ate and left no crumbs. 💅
And ooh, we can ALSO use those selection facilities to make a cute little tabular output with a summary for the logical types that are Enumerator. Again, sorted by type name:
llvm-debuginfo-analyzer --attribute=format,level
--output-sort=name
--select-types=Enumerator
--print=types,summary
pr-46466-*.o
Logical View:
[000] {File} 'pr-46466-codeview-clang.o' -> COFF-x86-64
[001] {CompileUnit} 'pr-46466.cpp'
[005] {Enumerator} 'BLUE' = '0x1'
[005] {Enumerator} 'RED' = '0x0'
-----------------------------
Element Total Found
-----------------------------
Scopes 5 0
Symbols 2 0
Types 6 2
Lines 0 0
-----------------------------
Total 13 2
Logical View:
[000] {File} 'pr-46466-codeview-msvc.o' -> COFF-i386
[001] {CompileUnit} 'pr-46466.cpp'
[005] {Enumerator} 'BLUE' = '0x1'
[005] {Enumerator} 'RED' = '0x0'
-----------------------------
Element Total Found
-----------------------------
Scopes 5 0
Symbols 2 0
Types 7 2
Lines 0 0
-----------------------------
Total 14 2
Logical View:
[000] {File} 'pr-46466-dwarf-clang.o' -> elf64-x86-64
[001] {CompileUnit} 'pr-46466.cpp'
-----------------------------
Element Total Found
-----------------------------
Scopes 4 0
Symbols 0 0
Types 0 0
Lines 0 0
-----------------------------
Total 4 0
Logical View:
[000] {File} 'pr-46466-dwarf-gcc.o' -> elf64-x86-64
[001] {CompileUnit} 'pr-46466.cpp'
[005] {Enumerator} 'BLUE' = '0x1'
[005] {Enumerator} 'RED' = '0x0'
-----------------------------
Element Total Found
-----------------------------
Scopes 5 0
Symbols 0 0
Types 2 2
Lines 0 0
-----------------------------
Total 7 2THE RECEIPTS. 🔍 Look at the numbers under the Found column and you'll clock it immediately: no Types were found in the DWARF debug info that Clang generated. Zero. Zilch. The math is mathing and it's mathing to nothing. 💀
TEST CASE 5 - INCORRECT LEXICAL SCOPE FOR VARIABLE 🧐✨
Okay so this next example is here to show you the different output that llvm-debuginfo-analyzer generates. We compiled it for an X86 Codeview target and an ELF target, using recent versions of Clang, GCC and MSVC (-O0 -g).
// definitions.h
#ifdef _MSC_VER
#define forceinline __forceinline
#elif defined(__clang__)
#if __has_attribute(__always_inline__)
#define forceinline inline __attribute__((__always_inline__))
#else
#define forceinline inline
#endif
#elif defined(__GNUC__)
#define forceinline inline __attribute__((__always_inline__))
#else
#define forceinline inline
#error
#endifSince this test depends on inline compiler options, that header file up there is what defines forceinline. Iconic little preprocessing moment. 🎀
#include "definitions.h"
1 #include "definitions.h"
2 forceinline int InlineFunction(int Param) {
3 int Var_1 = Param;
4 {
5 int Var_2 = Param + Var_1;
6 Var_1 = Var_2;
7 }
8 return Var_1;
9 }
10
11 int test(int Param_1, int Param_2) {
12 int A = Param_1;
13 A += InlineFunction(Param_2);
14 return A;
15 }This test exists to illustrate a variable issue that was found in the Clang compiler: PR43860 (Bugs LLVM) / PR43205 (GitHub). Not us being messy — that's a compiler bug, bestie, we're just the messenger. 🫶
So these are the logical views that llvm-debuginfo-analyzer generates for 3 different compilers (MSVC, Clang and GCC), emitting different debug information formats (CodeView, DWARF) on different platforms. Vibe check across the whole toolchain, let's gooo 🌈
llvm-debuginfo-analyzer --attribute=level,format,producer
--output-sort=name
--print=symbols
pr-43860-codeview-clang.o
pr-43860-codeview-msvc.o
pr-43860-dwarf-clang.o
pr-43860-dwarf-gcc.oCODEVIEW - Clang (Windows) 🪟
Logical View:
[000] {File} 'pr-43860-codeview-clang.o' -> COFF-x86-64
[001] {CompileUnit} 'pr-43860.cpp'
[002] {Producer} 'clang version 14.0.0'
[002] 2 {Function} inlined 'InlineFunction' -> 'int'
[003] {Parameter} '' -> 'int'
[002] {Function} extern not_inlined 'test' -> 'int'
[003] {Variable} 'A' -> 'int'
[003] {InlinedFunction} inlined 'InlineFunction' -> 'int'
[004] {Parameter} 'Param' -> 'int'
[004] {Variable} 'Var_1' -> 'int'
[004] {Variable} 'Var_2' -> 'int'
[003] {Parameter} 'Param_1' -> 'int'
[003] {Parameter} 'Param_2' -> 'int'CODEVIEW - MSVC (Windows) 🪟
Logical View:
[000] {File} 'pr-43860-codeview-msvc.o' -> COFF-i386
[001] {CompileUnit} 'pr-43860.cpp'
[002] {Producer} 'Microsoft (R) Optimizing Compiler'
[002] {Function} extern not_inlined 'InlineFunction' -> 'int'
[003] {Block}
[004] {Variable} 'Var_2' -> 'int'
[003] {Variable} 'Param' -> 'int'
[003] {Variable} 'Var_1' -> 'int'
[002] {Function} extern not_inlined 'test' -> 'int'
[003] {Variable} 'A' -> 'int'
[003] {Variable} 'Param_1' -> 'int'
[003] {Variable} 'Param_2' -> 'int'DWARF - Clang (Linux) 🐧
Logical View:
[000] {File} 'pr-43860-dwarf-clang.o' -> elf64-x86-64
[001] {CompileUnit} 'pr-43860.cpp'
[002] {Producer} 'clang version 14.0.0'
[002] 2 {Function} extern inlined 'InlineFunction' -> 'int'
[003] {Block}
[004] 5 {Variable} 'Var_2' -> 'int'
[003] 2 {Parameter} 'Param' -> 'int'
[003] 3 {Variable} 'Var_1' -> 'int'
[002] 11 {Function} extern not_inlined 'test' -> 'int'
[003] 12 {Variable} 'A' -> 'int'
[003] 14 {InlinedFunction} inlined 'InlineFunction' -> 'int'
[004] {Block}
[005] {Variable} 'Var_2' -> 'int'
[004] {Parameter} 'Param' -> 'int'
[004] {Variable} 'Var_1' -> 'int'
[003] 11 {Parameter} 'Param_1' -> 'int'
[003] 11 {Parameter} 'Param_2' -> 'int'DWARF - GCC (Linux) 🐧
Logical View:
[000] {File} 'pr-43860-dwarf-gcc.o' -> elf64-x86-64
[001] {CompileUnit} 'pr-43860.cpp' [001] {CompileUnit} 'pr-43860.cpp'
[002] {Producer} 'GNU C++14 9.3.0'
[002] 2 {Function} extern declared_inlined 'InlineFunction' -> 'int'
[003] {Block}
[004] 5 {Variable} 'Var_2' -> 'int'
[003] 2 {Parameter} 'Param' -> 'int'
[003] 3 {Variable} 'Var_1' -> 'int'
[002] 11 {Function} extern not_inlined 'test' -> 'int'
[003] 12 {Variable} 'A' -> 'int'
[003] 13 {InlinedFunction} declared_inlined 'InlineFunction' -> 'int'
[004] {Block}
[005] {Variable} 'Var_2' -> 'int'
[004] {Parameter} 'Param' -> 'int'
[004] {Variable} 'Var_1' -> 'int'
[003] 11 {Parameter} 'Param_1' -> 'int'
[003] 11 {Parameter} 'Param_2' -> 'int'okay so from those previous logical views, bestie, we can literally see that the CodeView debug information generated by the Clang compiler shows the variables Var_1 and Var_2 are at the same lexical scope (4) in the function InlineFuction. The DWARF generated by GCC/Clang and CodeView generated by MSVC, show those variables at the correct lexical scope: 3 and 4 respectively. no cap, that's the tea 🍵
Using the llvm-debuginfo-analyzer selection facilities, we can lowkey produce a simple tabular output showing just the logical elements that have in their name the var pattern. The logical view is sorted by the variables name. slay ✨
llvm-debuginfo-analyzer --attribute=level,format
--output-sort=name
--select-regex --select-nocase --select=Var
--report=list
--print=symbols
pr-43860-*.o Logical View:
[000] {File} 'pr-43860-codeview-clang.o' -> COFF-x86-64
[001] {CompileUnit} 'pr-43860.cpp'
[004] {Variable} 'Var_1' -> 'int'
[004] {Variable} 'Var_2' -> 'int'
Logical View:
[000] {File} 'pr-43860-codeview-msvc.o' -> COFF-i386
[001] {CompileUnit} 'pr-43860.cpp'
[003] {Variable} 'Var_1' -> 'int'
[004] {Variable} 'Var_2' -> 'int'
Logical View:
[000] {File} 'pr-43860-dwarf-clang.o' -> elf64-x86-64
[001] {CompileUnit} 'pr-43860.cpp'
[004] {Variable} 'Var_1' -> 'int'
[003] 3 {Variable} 'Var_1' -> 'int'
[005] {Variable} 'Var_2' -> 'int'
[004] 5 {Variable} 'Var_2' -> 'int'
Logical View:
[000] {File} 'pr-43860-dwarf-gcc.o' -> elf64-x86-64
[001] {CompileUnit} 'pr-43860.cpp'
[004] {Variable} 'Var_1' -> 'int'
[003] 3 {Variable} 'Var_1' -> 'int'
[005] {Variable} 'Var_2' -> 'int'
[004] 5 {Variable} 'Var_2' -> 'int'It also shows, that the CodeView debug information does not generate source code line numbers for the those logical symbols. The logical view is sorted by the types name. 😭
🌈 TEST CASE 6 - FULL LOGICAL VIEW 🌈
For advanced users, llvm-debuginfo-analyzer can display low level information that includes offsets within the debug information section, debug location operands, linkage names, etc. it's giving main character energy fr fr 👑
llvm-debuginfo-analyzer --attribute=all
--print=all
test-dwarf-clang.o Logical View:
[0x0000000000][000] {File} 'test-dwarf-clang.o' -> elf64-x86-64
[0x000000000b][001] {CompileUnit} 'test.cpp'
[0x000000000b][002] {Producer} 'clang version 12.0.0'
{Directory} ''
{File} 'test.cpp'
{Public} 'foo' [0x0000000000:0x000000003a]
[0x000000000b][002] {Range} Lines 2:9 [0x0000000000:0x000000003a]
[0x00000000bc][002] {BaseType} 'bool'
[0x0000000099][002] {BaseType} 'int'
[0x00000000b5][002] {BaseType} 'unsigned int'
[0x00000000a0][002] {Source} '/test.cpp'
[0x00000000a0][002] 1 {TypeAlias} 'INTPTR' -> [0x00000000ab]'* const int'
[0x000000002a][002] 2 {Function} extern not_inlined 'foo' -> [0x0000000099]'int'
[0x000000002a][003] {Range} Lines 2:9 [0x0000000000:0x000000003a]
[0x000000002a][003] {Linkage} 0x2 '_Z3fooPKijb'
[0x0000000071][003] {Block}
[0x0000000071][004] {Range} Lines 5:8 [0x000000001c:0x000000002f]
[0x000000007e][004] 5 {Variable} 'CONSTANT' -> [0x00000000c3]'const INTEGER'
[0x000000007e][005] {Coverage} 100.00%
[0x000000007f][005] {Location}
[0x000000007f][006] {Entry} Stack Offset: -28 (0xffffffffffffffe4) [DW_OP_fbreg]
[0x000000001c][004] 5 {Line} {NewStatement} '/test.cpp'
[0x000000001c][004] {Code} 'movl $0x7, -0x1c(%rbp)'
[0x0000000023][004] 6 {Line} {NewStatement} '/test.cpp'
[0x0000000023][004] {Code} 'movl $0x7, -0x4(%rbp)'
[0x000000002a][004] {Code} 'jmp 0x6'
[0x000000002f][004] 8 {Line} {NewStatement} '/test.cpp'
[0x000000002f][004] {Code} 'movl -0x14(%rbp), %eax'
[0x0000000063][003] 2 {Parameter} 'ParamBool' -> [0x00000000bc]'bool'
[0x0000000063][004] {Coverage} 100.00%
[0x0000000064][004] {Location}
[0x0000000064][005] {Entry} Stack Offset: -21 (0xffffffffffffffeb) [DW_OP_fbreg]
[0x0000000047][003] 2 {Parameter} 'ParamPtr' -> [0x00000000a0]'INTPTR'
[0x0000000047][004] {Coverage} 100.00%
[0x0000000048][004] {Location}
[0x0000000048][005] {Entry} Stack Offset: -16 (0xfffffffffffffff0) [DW_OP_fbreg]
[0x0000000055][003] 2 {Parameter} 'ParamUnsigned' -> [0x00000000b5]'unsigned int'
[0x0000000055][004] {Coverage} 100.00%
[0x0000000056][004] {Location}
[0x0000000056][005] {Entry} Stack Offset: -20 (0xffffffffffffffec) [DW_OP_fbreg]
[0x000000008d][003] 4 {TypeAlias} 'INTEGER' -> [0x0000000099]'int'
[0x0000000000][003] 2 {Line} {NewStatement} '/test.cpp'
[0x0000000000][003] {Code} 'pushq %rbp'
[0x0000000001][003] {Code} 'movq %rsp, %rbp'
[0x0000000004][003] {Code} 'movb %dl, %al'
[0x0000000006][003] {Code} 'movq %rdi, -0x10(%rbp)'
[0x000000000a][003] {Code} 'movl %esi, -0x14(%rbp)'
[0x000000000d][003] {Code} 'andb $0x1, %al'
[0x000000000f][003] {Code} 'movb %al, -0x15(%rbp)'
[0x0000000012][003] 3 {Line} {NewStatement} {PrologueEnd} '/test.cpp'
[0x0000000012][003] {Code} 'testb $0x1, -0x15(%rbp)'
[0x0000000016][003] {Code} 'je 0x13'
[0x0000000032][003] 8 {Line} '/test.cpp'
[0x0000000032][003] {Code} 'movl %eax, -0x4(%rbp)'
[0x0000000035][003] 9 {Line} {NewStatement} '/test.cpp'
[0x0000000035][003] {Code} 'movl -0x4(%rbp), %eax'
[0x0000000038][003] {Code} 'popq %rbp'
[0x0000000039][003] {Code} 'retq'
[0x000000003a][003] 9 {Line} {NewStatement} {EndSequence} '/test.cpp' -----------------------------
Element Total Printed
-----------------------------
Scopes 3 3
Symbols 4 4
Types 5 5
Lines 25 25
-----------------------------
Total 37 37 Scope Sizes:
189 (100.00%) : [0x000000000b][001] {CompileUnit} 'test.cpp'
110 ( 58.20%) : [0x000000002a][002] 2 {Function} extern not_inlined 'foo' -> [0x0000000099]'int'
27 ( 14.29%) : [0x0000000071][003] {Block}
Totals by lexical level:
[001]: 189 (100.00%)
[002]: 110 ( 58.20%)
[003]: 27 ( 14.29%)The Scope Sizes table shows the contribution in bytes to the debug information by each scope, which can be used to determine unexpected size changes in the DWARF sections between different versions of the same toolchain. vibe check that 📏
[0x000000002a][002] 2 {Function} extern not_inlined 'foo' -> [0x0000000099]'int'
[0x000000002a][003] {Range} Lines 2:9 [0x0000000000:0x000000003a]
[0x000000002a][003] {Linkage} 0x2 '_Z3fooPKijb'
[0x0000000071][003] {Block}
[0x0000000071][004] {Range} Lines 5:8 [0x000000001c:0x000000002f]
[0x000000007e][004] 5 {Variable} 'CONSTANT' -> [0x00000000c3]'const INTEGER'
[0x000000007e][005] {Coverage} 100.00%
[0x000000007f][005] {Location}
[0x000000007f][006] {Entry} Stack Offset: -28 (0xffffffffffffffe4) [DW_OP_fbreg]The {Range} attribute describe the line ranges for a logical scope. For this case, the function foo is within the lines 2 and 9. periodt 💅
The {Coverage} and {Location} attributes describe the debug location and coverage for logical symbols. For optimized code, the coverage value decreases and it affects the program debuggability. lowkey important 💜
🚪 EXIT STATUS 🚪
llvm-debuginfo-analyzer returns 0 if the input files were parsed and printed successfully. Otherwise, it returns 1. that's it, bestie ✨
👀 SEE ALSO 👀
llvm-dwarfdump
✨ AUTHOR ✨
Maintained by the LLVM Team (https://llvm.org/). 🫶
📜 COPYRIGHT 📜
2003-2024, LLVM Project 🎀
💖 and that's the whole page, bestie! this was LLVM-DEBUGINFO-ANALYZER(1), dated 2024-04-14. stay iconic 🌸
📦 where this page comes from
- ubuntu noble: llvm-16 1:16.0.6-23ubuntu4 · APACHE-2-LLVM-EXCEPTIONS
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