llvm-dwarfdump - dump and verify DWARF debug information¶

SYNOPSIS¶

llvm-dwarfdump [options] [filename …]

DESCRIPTION¶

llvm-dwarfdump parses DWARF sections in object files, archives, and .dSYM bundles and prints their contents in human-readable form. Only the .debug_info section is printed unless one of the section-specific options or --all is specified.

If no input file is specified, a.out is used instead. If - is used as the input file, llvm-dwarfdump reads the input from its standard input stream.

OPTIONS¶

:::{option} -a, –all Dump all supported DWARF sections. :::

:::{option} –arch= Dump DWARF debug information for the specified CPU architecture. Architectures may be specified by name or by number. This option can be specified multiple times, once for each desired architecture. All CPU architectures will be printed by default. :::

:::{option} -c, –show-children Show a debug info entry’s children when selectively printing with the =<offset> argument of --debug-info, or options such as --find or --name. :::

:::{option} –color Use colors in output. :::

:::{option} –error-display= Set the level of detail and summary to display when verifying. Implies --verify. The supported values are:

quiet - Only display whether errors occurred. summary - Display only a summary of the errors found. details - Display each error in detail but no summary. full - Display each error as well as a summary. [default] :::

:::{option} -f , –find= Search for the exact text <name> in the accelerator tables and print the matching debug information entries. When there is no accelerator tables or the name of the DIE you are looking for is not found in the accelerator tables, try using the slower but more complete --name option. :::

:::{option} -F, –show-form Show DWARF form types after the DWARF attribute types. :::

:::{option} -h, –help Show help and usage for this command. :::

:::{option} –help-list Show help and usage for this command without grouping the options into categories. :::

:::{option} -i, –ignore-case Ignore case distinctions when using --name. :::

:::{option} -n , –name= Find and print all debug info entries whose name (DW_AT_name/DW_AT_linkage_name attribute) is <name>. :::

:::{option} –lookup=

Look up <address> in the debug information and print out the file, function, block, and line table details. :::

:::{option} -o Redirect output to a file specified by <path>, where - is the standard output stream. :::

:::{option} -p, –show-parents Show a debug info entry’s parents when selectively printing with the =<offset> argument of --debug-info, or options such as --find or --name. :::

:::{option} –parent-recurse-depth= When displaying debug info entry parents, only show them to a maximum depth of <N>. :::

:::{option} –quiet Use with --verify to not emit to STDOUT. :::

:::{option} -r , –recurse-depth= When displaying debug info entries, only show children to a maximum depth of <N>. :::

:::{option} –show-section-sizes Show the sizes of all debug sections, expressed in bytes. :::

:::{option} –show-sources Print all source files mentioned in the debug information. Absolute paths are given whenever possible. :::

:::{option} –statistics Collect debug info quality metrics and print the results as machine-readable single-line JSON output. The output format is described in the section below (FORMAT OF STATISTICS OUTPUT). :::

:::{option} –summarize-types Abbreviate the description of type unit entries. :::

:::{option} -t, –filter-child-tag Only dump children whose DWARF tag is one of the specified tags. Example usage:

llvm-dwarfdump -t DW_TAG_structure_type -t DW_TAG_member -c

:::

:::{option} -x, –regex Treat any <name> strings as regular expressions when searching with --name. If --ignore-case is also specified, the regular expression becomes case-insensitive. :::

:::{option} -u, –uuid Show the UUID for each architecture. :::

:::{option} –diff Dump the output in a format that is more friendly for comparing DWARF output from two different files. :::

:::{option} -v, –verbose Display verbose information when dumping. This can help to debug DWARF issues. :::

:::{option} –verify Verify the structure of the DWARF information by verifying the compile unit chains, DIE relationships graph, address ranges, and more. :::

:::{option} –verify-json= Output JSON-formatted error summary to the file specified by <path>. Implies --verify. The output format is described in the section below (FORMAT OF VERIFY JSON OUTPUT). :::

:::{option} –version Display the version of the tool. :::

:::{option} –debug-abbrev, –debug-addr, –debug-aranges, –debug-cu-index, –debug-frame [=], –debug-gnu-pubnames, –debug-gnu-pubtypes, –debug-info [=], –debug-line [=], –debug-line-str, –debug-loc [=], –debug-loclists [=], –debug-macro, –debug-names, –debug-pubnames, –debug-pubtypes, –debug-ranges, –debug-rnglists, –debug-str, –debug-str-offsets, –debug-tu-index, –debug-types [=], –eh-frame [=], –gdb-index, –apple-names, –apple-types, –apple-namespaces, –apple-objc Dump the specified DWARF section by name. Only the .debug_info section is shown by default. Some entries support adding an =<offset> as a way to provide an optional offset of the exact entry to dump within the respective section. When an offset is provided, only the entry at that offset will be dumped, else the entire section will be dumped.

The --debug-macro option prints both the .debug_macro and the .debug_macinfo sections.

The --debug-frame and --eh-frame options are aliases, in cases where both sections are present one command outputs both. :::

:::{option} –show-variable-coverage Show per-variable coverage metrics. The output format is described in the section below (FORMAT OF VARIABLE COVERAGE OUTPUT). :::

:::{option} –coverage-baseline File to use as the baseline for variable coverage statistics (implies --show-variable-coverage) :::

:::{option} –variable-coverage-bitcode-file File containing LLVM IR (bitcode or textual) used for calculating variable definedness in coverage statistics (implies --show-variable-coverage) :::

:::{option} –variable-coverage-maybe-undefined Use with --show-variable-coverage and --variable-coverage-bitcode-file to consider variables live if they are defined on at least one path (default behaviour is to require a variable to be defined on all paths to be counted) :::

:::{option} –combine-inline-variable-instances Use with --show-variable-coverage to average variable coverage across inlined subroutine instances instead of printing them separately. :::

:::{option} @ Read command-line options from <FILE>. :::

FORMAT OF STATISTICS OUTPUT¶

The --statistics option generates single-line JSON output representing quality metrics of the processed debug info. These metrics are useful to compare changes between two compilers, particularly for judging the effect that a change to the compiler has on the debug info quality.

The output is formatted as key-value pairs. The first pair contains a version number. The following naming scheme is used for the keys:

variables ==> local variables and parameters
local vars ==> local variables
params ==> formal parameters

For aggregated values, the following keys are used:

sum_of_all_variables(...) ==> the sum applied to all variables
#bytes ==> the number of bytes
#variables - entry values ... ==> the number of variables excluding the entry values etc.

FORMAT OF VERIFY JSON OUTPUT¶

The format of the JSON output created by the --verify-json is:

{
  "error-categories": {
    "<first category description>": {"count": 1234},
    "<next category description>": {"count": 4321}
  },
  "error-count": 5555
}

The following is generated if there are no errors reported:

{
  "error-categories": {},
  "error-count": 0
}

FORMAT OF VARIABLE COVERAGE OUTPUT¶

The --show-variable-coverage option differs from --statistics by printing per-variable debug info coverage metrics based on the number of source lines covered instead of the number of instruction bytes. Compared to counting instruction bytes, this is more stable across compilations and better reflects the debugging experience. The output is a tab-separated table containing the following columns:

Function ==> Name of the function the variable was found in
InstanceCount (when --combine-inline-variable-instances is specified) ==> Number of instances of the function; this is 1 for functions that have not been inlined, and n+1 for functions that have been inlined n times
InlChain (when --combine-inline-variable-instances is not specified) ==> Chain of call sites (file and line number) that the function has been inlined into; this will be empty if the function has not been inlined
Variable ==> Name of the variable
Decl ==> Source location (file and line number) of the variable’s declaration
LinesCovered ==> Number of source lines covered by the variable’s debug information in the input file
Baseline (empty if --coverage-baseline is not specified) ==> Number of source lines covered by the variable’s debug information in the baseline
CoveredRatio (empty if --coverage-baseline is not specified) ==> Ratio of the coverage compared to the baseline (calculated as LinesCovered/Baseline)
LinesPresent (empty if --coverage-baseline is not specified) ==> Number of source lines covered in the variable’s baseline debug information that are also present in the input file’s line table
LinesPresentRatio (empty if --coverage-baseline is not specified) ==> Ratio of the line table coverage compared to the baseline (calculated as LinesPresent/Baseline)

EXIT STATUS¶

llvm-dwarfdump returns 0 if the input files were parsed and dumped successfully. Otherwise, it returns 1.