Bloaty McBloatface: a size profiler for binaries
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README.md

Bloaty McBloatface: a size profiler for binaries

Build Status

Ever wondered what's making your ELF or Mach-O binary big? Bloaty McBloatface will show you a size profile of the binary so you can understand what's taking up space inside.

Bloaty works on binaries, shared objects, object files, and static libraries (.a files). It supports ELF/DWARF and Mach-O, though the Mach-O support is much more preliminary (it shells out to otool/symbols instead of parsing the file directly).

This is not an official Google product.

Building Bloaty

Bloaty uses CMake to build. All dependencies are included as Git submodules. To build, simply run:

$ cmake .
$ make -j6

To run tests, type:

$ make test

All the normal CMake features are available, like out-of-source builds:

$ mkdir build
$ cd build
$ cmake ..
$ make -j6

Running Bloaty

Run it directly on a binary target. For example, run it on itself.

$ ./bloaty bloaty

On Linux you'll see output something like:

     VM SIZE                         FILE SIZE
 --------------                   --------------
   0.0%       0 .debug_info        13.0Mi  37.6%
   0.0%       0 .debug_loc         7.45Mi  21.5%
   0.0%       0 .debug_str         5.14Mi  14.8%
  40.1%  2.17Mi .text              2.17Mi   6.3%
   0.0%       0 .debug_ranges      1.83Mi   5.3%
  30.6%  1.66Mi .rodata            1.66Mi   4.8%
   0.0%       0 .debug_line         878Ki   2.5%
   0.0%       0 .strtab             458Ki   1.3%
   7.1%   394Ki .rela.dyn           394Ki   1.1%
   6.4%   357Ki .dynstr             357Ki   1.0%
   5.5%   307Ki .data.rel.ro        307Ki   0.9%
   0.0%       0 .debug_abbrev       283Ki   0.8%
   4.2%   235Ki .eh_frame           235Ki   0.7%
   0.0%       0 .symtab             187Ki   0.5%
   2.2%   123Ki .dynsym             123Ki   0.3%
   1.0%  54.1Ki .data              54.1Ki   0.2%
   0.8%  44.6Ki .gcc_except_table  44.6Ki   0.1%
   0.7%  39.6Ki .gnu.hash          39.6Ki   0.1%
   0.7%  36.5Ki .eh_frame_hdr      36.5Ki   0.1%
   0.5%  30.0Ki [24 Others]        29.7Ki   0.1%
   0.0%       0 .debug_aranges     27.3Ki   0.1%
 100.0%  5.42Mi TOTAL              34.7Mi 100.0%

The "VM SIZE" column tells you how much space the binary will take when it is loaded into memory. The "FILE SIZE" column tells you about how much space the binary is taking on disk. These two can be very different from each other:

  • Some data lives in the file but isn't loaded into memory, like debug information.
  • Some data is mapped into memory but doesn't exist in the file. This mainly applies to the .bss section (zero-initialized data).

The default breakdown in Bloaty is by sections, but many other ways of slicing the binary are supported such as symbols and segments. If you compiled with debug info, you can even break down by compile units and inlines!

$ ./bloaty bloaty -d compileunits
     VM SIZE                                                                                FILE SIZE
 --------------                                                                          --------------
  62.3%  3.04Mi [None]                                                                    31.1Mi  94.4%
  11.2%   557Ki [91 Others]                                                                556Ki   1.7%
   3.7%   182Ki third_party/protobuf/src/google/protobuf/descriptor.cc                     179Ki   0.5%
   3.2%   162Ki third_party/protobuf/src/google/protobuf/descriptor.pb.cc                  161Ki   0.5%
   2.4%   117Ki third_party/capstone/arch/AArch64/AArch64InstPrinter.c                     117Ki   0.3%
   2.1%   103Ki third_party/capstone/arch/ARM/ARMDisassembler.c                            103Ki   0.3%
   1.9%  96.5Ki third_party/capstone/arch/Sparc/SparcInstPrinter.c                        96.5Ki   0.3%
   1.6%  82.1Ki third_party/demumble/third_party/libcxxabi/cxa_demangle.cpp               82.1Ki   0.2%
   1.5%  74.7Ki third_party/capstone/arch/PowerPC/PPCInstPrinter.c                        74.7Ki   0.2%
   1.2%  61.8Ki third_party/protobuf/src/google/protobuf/generated_message_reflection.cc  61.8Ki   0.2%
   1.2%  59.8Ki src/bloaty.cc                                                             59.7Ki   0.2%
   1.1%  55.1Ki third_party/protobuf/src/google/protobuf/text_format.cc                   55.1Ki   0.2%
   0.9%  43.3Ki third_party/capstone/arch/ARM/ARMInstPrinter.c                            43.3Ki   0.1%
   0.8%  41.9Ki third_party/re2/re2/parse.cc                                              41.9Ki   0.1%
   0.8%  39.1Ki third_party/protobuf/src/google/protobuf/map_field.cc                     39.1Ki   0.1%
   0.7%  36.1Ki third_party/protobuf/src/google/protobuf/wire_format.cc                   36.1Ki   0.1%
   0.7%  36.0Ki src/dwarf.cc                                                              36.0Ki   0.1%
   0.7%  35.3Ki third_party/re2/re2/re2.cc                                                35.3Ki   0.1%
   0.7%  33.8Ki third_party/protobuf/src/google/protobuf/extension_set.cc                 33.8Ki   0.1%
   0.6%  30.8Ki third_party/capstone/arch/AArch64/AArch64Disassembler.c                   30.8Ki   0.1%
   0.6%  29.4Ki third_party/re2/re2/dfa.cc                                                29.4Ki   0.1%
 100.0%  4.87Mi TOTAL                                                                     32.9Mi 100.0%

Run Bloaty with --help to see a list of available options:

$ ./bloaty --help
Bloaty McBloatface: a size profiler for binaries.

USAGE: bloaty [options] file... [-- base_file...]

Options:

  --csv              Output in CSV format instead of human-readable.
  -c <file>          Load configuration from <file>.
  -d <sources>       Comma-separated list of sources to scan.
  -C <mode>          How to demangle symbols.  Possible values are:
  --demangle=<mode>    --demangle=none   no demangling, print raw symbols
                       --demangle=short  demangle, but omit arg/return types
                       --demangle=full   print full demangled type
                     The default is --demangle=short.
  --disassemble=<function>
                     Disassemble this function (EXPERIMENTAL)
  -n <num>           How many rows to show per level before collapsing
                     other keys into '[Other]'.  Set to '0' for unlimited.
                     Defaults to 20.
  -s <sortby>        Whether to sort by VM or File size.  Possible values
                     are:
                       -s vm
                       -s file
                       -s both (the default: sorts by max(vm, file)).
  -w                 Wide output; don't truncate long labels.
  --help             Display this message and exit.
  --list-sources     Show a list of available sources and exit.

Options for debugging Bloaty:

  --debug-vmaddr=ADDR
  --debug-fileoff=OFF
                     Print extended debugging information for the given
                     VM address and/or file offset.
  -v                 Verbose output.  Dumps warnings encountered during
                     processing and full VM/file maps at the end.
                     Add more v's (-vv, -vvv) for even more.

Size Diffs

You can use Bloaty to see how the size of a binary changed. On the command-line, pass -- followed by the files you want to use as the diff base.

For example, here is a size diff between a couple different versions of Bloaty, showing how it grew when I added some features.

$ ./bloaty bloaty -- oldbloaty
     VM SIZE                     FILE SIZE
 --------------               --------------
  [ = ]       0 .debug_loc     +688Ki  +9.9%
   +19%  +349Ki .text          +349Ki   +19%
  [ = ]       0 .debug_ranges  +180Ki   +11%
  [ = ]       0 .debug_info    +120Ki  +0.9%
   +23% +73.5Ki .rela.dyn     +73.5Ki   +23%
  +3.5% +57.1Ki .rodata       +57.1Ki  +3.5%
 +28e3% +53.9Ki .data         +53.9Ki +28e3%
  [ = ]       0 .debug_line   +40.2Ki  +4.8%
  +2.3% +5.35Ki .eh_frame     +5.35Ki  +2.3%
  -6.0%      -5 [Unmapped]    +2.65Ki  +215%
  +0.5% +1.70Ki .dynstr       +1.70Ki  +0.5%
  [ = ]       0 .symtab       +1.59Ki  +0.9%
  [ = ]       0 .debug_abbrev +1.29Ki  +0.5%
  [ = ]       0 .strtab       +1.26Ki  +0.3%
   +16%    +992 .bss                0  [ = ]
  +0.2%    +642 [13 Others]      +849  +0.2%
  +0.6%    +792 .dynsym          +792  +0.6%
   +16%    +696 .rela.plt        +696   +16%
   +16%    +464 .plt             +464   +16%
  +0.8%    +312 .eh_frame_hdr    +312  +0.8%
  [ = ]       0 .debug_str    -19.6Ki  -0.4%
   +11%  +544Ki TOTAL         +1.52Mi  +4.6%

Each line shows the how much each part changed compared to its previous size. Most sections grew, but one section at the bottom (.debug_str) shrank. The "TOTAL" line shows how much the size changed overall.

Hierarchical Profiles

Bloaty supports breaking the binary down in lots of different ways. You can combine multiple data sources into a single hierarchical profile. For example, we can use the segments and sections data sources in a single report:

$ bloaty -d segments,sections bloaty
      VM SIZE                              FILE SIZE
 --------------                        --------------
   0.0%       0 [Unmapped]              7.31Mi  94.2%
      -NAN%       0 .debug_info             2.97Mi  40.6%
      -NAN%       0 .debug_loc              2.30Mi  31.5%
      -NAN%       0 .debug_str              1.03Mi  14.2%
      -NAN%       0 .debug_ranges            611Ki   8.2%
      -NAN%       0 .debug_line              218Ki   2.9%
      -NAN%       0 .debug_abbrev           85.4Ki   1.1%
      -NAN%       0 .strtab                 62.8Ki   0.8%
      -NAN%       0 .symtab                 27.8Ki   0.4%
      -NAN%       0 .debug_aranges          13.5Ki   0.2%
      -NAN%       0 [Unmapped]              2.82Ki   0.0%
      -NAN%       0 .shstrtab                  371   0.0%
      -NAN%       0 .comment                    43   0.0%
  99.2%   452Ki LOAD [RX]                452Ki   5.7%
      73.4%   332Ki .text                    332Ki  73.4%
      13.3%  60.0Ki .rodata                 60.0Ki  13.3%
       7.0%  31.8Ki .eh_frame               31.8Ki   7.0%
       2.3%  10.5Ki .gcc_except_table       10.5Ki   2.3%
       0.9%  4.18Ki .eh_frame_hdr           4.18Ki   0.9%
       0.8%  3.54Ki .dynsym                 3.54Ki   0.8%
       0.8%  3.52Ki .dynstr                 3.52Ki   0.8%
       0.7%  2.98Ki .rela.plt               2.98Ki   0.7%
       0.4%  2.00Ki .plt                    2.00Ki   0.4%
       0.1%     568 [ELF Headers]              568   0.1%
       0.1%     408 .rela.dyn                  408   0.1%
       0.1%     304 .gnu.version_r             304   0.1%
       0.1%     302 .gnu.version               302   0.1%
       0.0%     216 .gnu.hash                  216   0.0%
       0.0%      36 .note.gnu.build-id          36   0.0%
       0.0%      32 .note.ABI-tag               32   0.0%
       0.0%      28 .interp                     28   0.0%
       0.0%      26 .init                       26   0.0%
       0.0%      18 [Unmapped]                  18   0.0%
       0.0%       9 .fini                        9   0.0%
   0.8%  3.46Ki LOAD [RW]               1.88Ki   0.0%
      45.6%  1.58Ki .bss                         0   0.0%
      29.3%  1.02Ki .got.plt                1.02Ki  54.1%
      14.9%     528 .dynamic                   528  27.4%
       7.1%     252 .data                      252  13.1%
       1.4%      48 .init_array                 48   2.5%
       0.7%      24 .got                        24   1.2%
       0.5%      16 [Unmapped]                  16   0.8%
       0.2%       8 .fini_array                  8   0.4%
       0.2%       8 .jcr                         8   0.4%
       0.1%       4 [None]                       0   0.0%
   0.0%       0 [ELF Headers]           2.38Ki   0.0%
 100.0%   456Ki TOTAL                   7.75Mi 100.0%

Bloaty displays a maximum of 20 lines for each level; other values are grouped into an [Other] bin. Use -n <num> to override this setting. If you pass -n 0, all data will be output without collapsing anything into [Other].

Debugging Stripped Binaries

Bloaty supports reading debuginfo/symbols from separate binaries. This lets you profile a stripped binary, even for data sources like "compileunits" or "symbols" that require this extra information.

Bloaty uses build IDs to verify that the binary and the debug file match. Otherwise the results would be nonsense (this kind of mismatch might sound unlikely but it's a very easy mistake to make, and one that I made several times even as Bloaty's author!).

Make sure you are compiling with build IDs enabled. For gcc this happens automatically, but Clang decided not to make this the default, since it makes the link slower. For Clang add -Wl,--build-id to your link line. (If you want a slightly faster link and don't care about reproducibility, you can use -Wl,--build-id=uuid instead).

Then you can strip the binary and uses the unstripped binary as your debug file. For example, with bloaty itself:

$ cp bloaty bloaty.stripped
$ strip bloaty.stripped
$ ./bloaty -d compileunits --debug-file=bloaty bloaty.stripped

It is also possible to remove debug sections only (see objcopy --strip-debug) while keeping the symbol table. You can also create debug file that contain only debug info (see objcopy --only-keep-debug).

Bloaty does not currently support the GNU debuglink or looking up debug files by build ID, which are the methods GDB uses to find debug files. If there are use cases where Bloaty's --debug-file option won't work, we can reconsider implementing these.

Configuration Files

Any options that you can specify on the command-line, you can put into a configuration file instead. Then use can use -c FILE to load those options from the config file. Also, a few features are only available with configuration files and cannot be specify on the command-line.

The configuration file is a in Protocol Buffers text format. The schema is the Options message in src/bloaty.proto.

The two most useful cases for configuration files are:

  1. You have too many input files to put on the command-line. At Google we sometimes run Bloaty over thousands of input files. This can cause the overall command-line to exceed OS limits. With a config file, we can avoid this:

    filename: "path/to/long_filename_a.o"
    filename: "path/to/long_filename_b.o"
    filename: "path/to/long_filename_c.o"
    # ...repeat for thousands of files.
    
  2. For custom data sources, it can be very useful to put them in a config file, for greater reusability. For example, see the custom data sources defined in custom_sources.bloaty. Also read more about custom data sources below.

Data Sources

Bloaty has many data sources built in. These all provide different ways of looking at the binary. You can also create your own data sources by applying regexes to the built-in data sources (see "Custom Data Sources" below).

While Bloaty works on binaries, shared objects, object files, and static libraries (.a files), some of the data sources don't work on object files. This applies especially to data sources that read debug info.

Segments

Segments are what the run-time loader uses to determine what parts of the binary need to be loaded/mapped into memory. There are usually just a few segments: one for each set of mmap() permissions required:

$ bloaty -d segments bloaty
      VM SIZE                     FILE SIZE
 --------------               --------------
   0.0%       0 [Unmapped]     7.31Mi  94.2%
  99.2%   452Ki LOAD [RX]       452Ki   5.7%
   0.8%  3.46Ki LOAD [RW]      1.88Ki   0.0%
   0.0%       0 [ELF Headers]  2.38Ki   0.0%
 100.0%   456Ki TOTAL          7.75Mi 100.0%

Here we see one segment mapped [R E] (read/execute) and one segment mapped [RW ] (read/write). A large part of the binary is not loaded into memory, which we see as [Unmapped].

Object files and static libraries don't have segments. However we fake it by grouping sections by their flags. This gives us a break-down sort of like real segments.

 $ ./bloaty bloaty -d segments src/bloaty.o
     VM SIZE                     FILE SIZE
 --------------               --------------
   0.0%       0 [Unmapped]     7.31Mi  67.6%
   0.0%       0 Section []     2.95Mi  27.3%
  85.2%   452Ki LOAD [RX]       452Ki   4.1%
  11.3%  59.8Ki Section [AX]   59.8Ki   0.5%
   0.0%       0 [ELF Headers]  28.3Ki   0.3%
   2.9%  15.4Ki Section [A]    15.4Ki   0.1%
   0.7%  3.46Ki LOAD [RW]      1.88Ki   0.0%
   0.0%      41 Section [AW]       20   0.0%
 100.0%   531Ki TOTAL          10.8Mi 100.0%

Sections

Sections give us a bit more granular look into the binary. If we want to find the symbol table, the unwind information, or the debug information, each kind of information lives in its own section. Bloaty's default output is sections.

$ bloaty -d sections bloaty
      VM SIZE                         FILE SIZE
 --------------                   --------------
   0.0%       0 .debug_info        2.97Mi  38.3%
   0.0%       0 .debug_loc         2.30Mi  29.7%
   0.0%       0 .debug_str         1.03Mi  13.3%
   0.0%       0 .debug_ranges       611Ki   7.7%
  72.8%   332Ki .text               332Ki   4.2%
   0.0%       0 .debug_line         218Ki   2.8%
   0.0%       0 .debug_abbrev      85.4Ki   1.1%
   0.0%       0 .strtab            62.8Ki   0.8%
  13.2%  60.0Ki .rodata            60.0Ki   0.8%
   7.0%  31.8Ki .eh_frame          31.8Ki   0.4%
   0.0%       0 .symtab            27.8Ki   0.3%
   0.0%       0 .debug_aranges     13.5Ki   0.2%
   2.3%  10.5Ki .gcc_except_table  10.5Ki   0.1%
   1.5%  6.77Ki [Other]            5.60Ki   0.1%
   0.9%  4.18Ki .eh_frame_hdr      4.18Ki   0.1%
   0.8%  3.54Ki .dynsym            3.54Ki   0.0%
   0.8%  3.52Ki .dynstr            3.52Ki   0.0%
   0.7%  2.98Ki .rela.plt          2.98Ki   0.0%
   0.1%     568 [ELF Headers]      2.93Ki   0.0%
   0.0%      34 [Unmapped]         2.85Ki   0.0%
   0.0%       4 [None]                  0   0.0%
 100.0%   456Ki TOTAL              7.75Mi 100.0%

Symbols

Symbols come from the symbol table, and represent individual functions or variables.

$ ./bloaty -d symbols bloaty
      VM SIZE                                                                                        FILE SIZE
 --------------                                                                                  --------------
  17.9%  81.9Ki [Unmapped]                                                                        7.39Mi  95.3%
  62.3%   283Ki [Other]                                                                            284Ki   3.6%
   2.7%  12.3Ki re2::RE2::Match(re2::StringPiece const&, int, int, re2::RE2::Anchor, re2::String  12.3Ki   0.2%
   1.7%  7.83Ki re2::unicode_groups                                                               7.83Ki   0.1%
   1.7%  7.56Ki re2::NFA::Search                                                                  7.56Ki   0.1%
   1.3%  5.76Ki re2::BitState::TrySearch                                                          5.76Ki   0.1%
   1.2%  5.43Ki bloaty::Bloaty::ScanAndRollupFile                                                 5.43Ki   0.1%
   1.0%  4.49Ki re2::DFA::DFA                                                                     4.49Ki   0.1%
   1.0%  4.35Ki bool bloaty::(anonymous namespace)::ForEachElf<bloaty::(anonymous namespace)::Do  4.35Ki   0.1%
   1.0%  4.34Ki re2::Regexp::Parse                                                                4.34Ki   0.1%
   0.9%  4.20Ki re2::RE2::Init                                                                    4.20Ki   0.1%
   0.9%  4.09Ki re2::Prog::IsOnePass                                                              4.09Ki   0.1%
   0.9%  4.04Ki re2::Compiler::PostVisit                                                          4.04Ki   0.1%
   0.9%  4.04Ki bloaty::ReadDWARFInlines                                                          4.04Ki   0.1%
   0.9%  3.91Ki re2::Regexp::FactorAlternationRecursive                                           3.91Ki   0.0%
   0.8%  3.77Ki re2::DFA::RunStateOnByte                                                          3.77Ki   0.0%
   0.8%  3.68Ki re2::unicode_casefold                                                             3.68Ki   0.0%
   0.8%  3.52Ki bloaty::ElfFileHandler::ProcessFile                                               3.52Ki   0.0%
   0.7%  3.40Ki re2::DFA::InlinedSearchLoop(re2::DFA::SearchParams*, bool, bool, bool) [clone .c  3.40Ki   0.0%
   0.7%  3.38Ki re2::DFA::InlinedSearchLoop(re2::DFA::SearchParams*, bool, bool, bool) [clone .c  3.38Ki   0.0%
   0.0%     165 [None]                                                                                 0   0.0%
 100.0%   456Ki TOTAL                                                                             7.75Mi 100.0%

You can control how symbols are demangled with the -C MODE or --demangle=MODE flag. You can also specify the demangling mode explicitly in the -d switch. We have three different demangling modes:

  • -C none or -d rawsymbols: no, demangling.
  • -C short or -d shortsymbols: short demangling: return types, template parameters, and function parameter types are omitted. For example: bloaty::dwarf::FormReader<>::GetFunctionForForm<>(). This is the default.
  • -C full or -d fullsymbols: full demangling.

One very handy thing about -C short (the default) is that it groups all template instantiations together, regardless of their parameters. You can use this to determine how much code size you are paying by doing multiple instantiations of templates. Try bloaty -d shortsymbols,fullsymbols.

Input Files

When you pass multiple files to Bloaty, the inputfiles source will let you break it down by input file:

$ ./bloaty -d inputfiles src/*.o
     VM SIZE                    FILE SIZE
 --------------              --------------
  51.8%  75.2Ki src/bloaty.o  3.05Mi  48.2%
  28.2%  40.9Ki src/dwarf.o   2.04Mi  32.2%
  12.1%  17.5Ki src/elf.o      579Ki   8.9%
   5.5%  7.99Ki src/macho.o    415Ki   6.4%
   2.5%  3.57Ki src/main.o     279Ki   4.3%
 100.0%   145Ki TOTAL         6.34Mi 100.0%

Archive Members

When you are running Bloaty on a .a file, the armembers source will let you break it down by .o file inside the archive.

./bloaty -d armembers src/libbloaty.a 
     VM SIZE                         FILE SIZE
 --------------                   --------------
  53.1%  75.2Ki bloaty.o           3.05Mi  50.1%
  28.9%  40.9Ki dwarf.o            2.04Mi  33.5%
  12.4%  17.5Ki elf.o               579Ki   9.3%
   5.6%  7.99Ki macho.o             415Ki   6.7%
   0.0%       0 [AR Symbol Table]  27.3Ki   0.4%
   0.0%       0 [AR Headers]          308   0.0%
 100.0%   141Ki TOTAL              6.10Mi 100.0%

You are free to use this data source even for non-.a files, but it won't be very useful since it will always just resolve to the input file (the .a file).

Compile Units

Using debug information, we can tell what compile unit (and corresponding source file) each bit of the binary came from. There are a couple different places in DWARF we can look for this information; currently we mainly use the .debug_aranges section. It's not perfect and sometimes you'll see some of the binary show up as [None] if it's not mentioned in aranges (improving this is a TODO). But it can tell us a lot.

 $ ./bloaty -d compileunits bloaty
     VM SIZE                            FILE SIZE
 --------------                      --------------
  27.9%   128Ki [None]                7.43Mi  95.9%
  12.9%  59.2Ki src/bloaty.cc         59.0Ki   0.7%
   7.3%  33.4Ki re2/re2.cc            32.3Ki   0.4%
   6.9%  31.6Ki re2/dfa.cc            31.6Ki   0.4%
   6.8%  31.4Ki re2/parse.cc          31.4Ki   0.4%
   6.7%  30.9Ki src/dwarf.cc          30.9Ki   0.4%
   6.7%  30.6Ki re2/regexp.cc         27.8Ki   0.4%
   5.1%  23.7Ki re2/compile.cc        23.7Ki   0.3%
   4.3%  19.7Ki re2/simplify.cc       19.7Ki   0.2%
   3.2%  14.8Ki src/elf.cc            14.8Ki   0.2%
   3.1%  14.2Ki re2/nfa.cc            14.2Ki   0.2%
   1.8%  8.34Ki re2/bitstate.cc       8.34Ki   0.1%
   1.7%  7.84Ki re2/prog.cc           7.84Ki   0.1%
   1.6%  7.13Ki re2/tostring.cc       7.13Ki   0.1%
   1.5%  6.67Ki re2/onepass.cc        6.67Ki   0.1%
   1.4%  6.58Ki src/macho.cc          6.58Ki   0.1%
   0.7%  3.27Ki src/main.cc           3.27Ki   0.0%
   0.2%     797 [Other]                  797   0.0%
   0.1%     666 util/stringprintf.cc     666   0.0%
   0.1%     573 util/strutil.cc          573   0.0%
   0.1%     476 util/rune.cc             476   0.0%
 100.0%   460Ki TOTAL                 7.75Mi 100.0%

Inlines

The DWARF debugging information also contains "line info" information that understands inlining. So within a function, it will know which instructions came from an inlined function from a header file. This is the information the debugger uses to point at a specific source line as you're tracing through a program.

$ ./bloaty -d inlines bloaty 
     VM SIZE                                                    FILE SIZE
 --------------                                              --------------
   2.4%   110Ki [None]                                        7.42Mi  95.6%
  90.3%  4.01Mi /usr/include/c++/4.8/bitsstl_vector.h:414     15.3Ki   0.2%
   5.5%   250Ki [Other]                                        250Ki   3.2%
   0.3%  11.4Ki /usr/include/c++/4.8/bitsbasic_string.h:539   11.4Ki   0.1%
   0.2%  8.81Ki /usr/include/c++/4.8ostream:535               8.81Ki   0.1%
   0.2%  7.59Ki /usr/include/c++/4.8/bitsbasic_ios.h:456      7.59Ki   0.1%
   0.1%  6.20Ki /usr/include/c++/4.8streambuf:466             6.20Ki   0.1%
   0.1%  6.06Ki /usr/include/c++/4.8/bitsbasic_string.h:249   6.06Ki   0.1%
   0.1%  4.24Ki /usr/include/c++/4.8/bitsbasic_string.h:240   4.24Ki   0.1%
   0.1%  3.61Ki /usr/include/c++/4.8/bitsbasic_ios.h:276      3.61Ki   0.0%
   0.1%  3.51Ki /usr/include/c++/4.8/extatomicity.h:81        3.51Ki   0.0%
   0.1%  3.19Ki /usr/include/c++/4.8/bitsbasic_string.h:583   3.19Ki   0.0%
   0.1%  3.06Ki /usr/include/c++/4.8/bitsbasic_string.h:293   3.06Ki   0.0%
   0.1%  2.94Ki /usr/include/c++/4.8/extnew_allocator.h:110   2.94Ki   0.0%
   0.1%  2.89Ki /usr/include/c++/4.8ostream:385               2.89Ki   0.0%
   0.1%  2.87Ki /usr/include/c++/4.8/bitsstl_construct.h:102  2.87Ki   0.0%
   0.1%  2.86Ki /usr/include/c++/4.8/extatomicity.h:84        2.86Ki   0.0%
   0.1%  2.76Ki /usr/include/c++/4.8/extatomicity.h:49        2.76Ki   0.0%
   0.1%  2.70Ki /usr/include/c++/4.8/bitschar_traits.h:271    2.70Ki   0.0%
   0.1%  2.62Ki /usr/include/c++/4.8/bitsbasic_string.h:275   2.62Ki   0.0%
   0.1%  2.58Ki /usr/include/c++/4.8ostream:93                2.58Ki   0.0%
 100.0%  4.45Mi TOTAL                                         7.75Mi 100.0%

Custom Data Sources

Sometimes you want to munge the labels from an existing data source. For example, when we use "compileunits" on Bloaty itself, we see files from all our dependencies mixed together:

$ ./bloaty -d compileunits bloaty
     VM SIZE                                                                                FILE SIZE
 --------------                                                                          --------------
  65.5%  3.21Mi [130 Others]                                                              12.3Mi  37.0%
   4.6%   232Ki third_party/protobuf/src/google/protobuf/descriptor.cc                    3.74Mi  11.2%
   5.6%   281Ki third_party/protobuf/src/google/protobuf/descriptor.pb.cc                 2.34Mi   7.0%
   1.8%  90.4Ki src/bloaty.cc                                                             2.15Mi   6.5%
   6.7%   335Ki third_party/capstone/arch/ARM/ARMDisassembler.c                           1.64Mi   4.9%
   1.3%  63.9Ki src/dwarf.cc                                                              1.32Mi   4.0%
   1.6%  82.2Ki third_party/demumble/third_party/libcxxabi/cxa_demangle.cpp               1.17Mi   3.5%
   1.5%  73.9Ki third_party/protobuf/src/google/protobuf/text_format.cc                    997Ki   2.9%
   1.7%  83.5Ki third_party/protobuf/src/google/protobuf/generated_message_reflection.cc   938Ki   2.7%
   0.6%  31.3Ki third_party/protobuf/src/google/protobuf/descriptor_database.cc            766Ki   2.2%
   1.0%  50.9Ki third_party/protobuf/src/google/protobuf/message.cc                        746Ki   2.2%
   0.7%  36.4Ki third_party/re2/re2/dfa.cc                                                 621Ki   1.8%
   0.8%  42.3Ki third_party/re2/re2/re2.cc                                                 618Ki   1.8%
   1.0%  48.3Ki third_party/protobuf/src/google/protobuf/extension_set.cc                  608Ki   1.8%
   0.9%  46.4Ki third_party/protobuf/src/google/protobuf/map_field.cc                      545Ki   1.6%
   0.7%  36.1Ki third_party/re2/re2/regexp.cc                                              538Ki   1.6%
   1.7%  86.9Ki third_party/capstone/arch/AArch64/AArch64Disassembler.c                    517Ki   1.5%
   0.8%  41.8Ki third_party/protobuf/src/google/protobuf/wire_format.cc                    513Ki   1.5%
   0.5%  25.4Ki third_party/protobuf/src/google/protobuf/generated_message_util.cc         511Ki   1.5%
   0.1%  4.33Ki src/main.cc                                                                483Ki   1.4%
   0.8%  41.3Ki src/bloaty.pb.cc                                                           465Ki   1.4%
 100.0%  4.91Mi TOTAL                                                                     33.4Mi 100.0%

If we want to bucket all of these by which library they came from, we can write a custom data source. It specifies the base data source and a set of regexes to apply to it. The regexes are tried in order, and the first matching regex will cause the entire label to be rewritten to the replacement text. Regexes follow RE2 syntax and the replacement can refer to capture groups.

custom_data_source: {
  name: "bloaty_package"
  base_data_source: "compileunits"

  rewrite: {
    pattern: "^(\\.\\./)?src"
    replacement: "src"
  }
  rewrite: {
    pattern: "^(\\.\\./)?(third_party/\\w+)"
    replacement: "\\2"
  }
}

Then use the data source like so:

$ ./bloaty -c config.bloaty -d bloaty_package bloaty
     VM SIZE                                   FILE SIZE
 --------------                             --------------
  21.7%  1.06Mi third_party/protobuf         14.2Mi  42.6%
  42.4%  2.08Mi third_party/capstone         6.88Mi  20.6%
   5.1%   256Ki src                          5.30Mi  15.9%
   5.5%   274Ki third_party/re2              3.97Mi  11.9%
   1.6%  82.2Ki third_party/demumble         1.17Mi   3.5%
   0.8%  38.0Ki third_party/abseil            526Ki   1.5%
   7.8%   390Ki [section .rodata]             390Ki   1.1%
   6.4%   320Ki [section .rela.dyn]           320Ki   0.9%
   4.6%   231Ki [section .eh_frame]           231Ki   0.7%
   0.0%       0 [section .debug_str]         82.7Ki   0.2%
   0.9%  44.8Ki [section .gcc_except_table]  44.8Ki   0.1%
   0.0%       0 [section .strtab]            40.5Ki   0.1%
   0.6%  31.5Ki [23 Others]                  38.8Ki   0.1%
   0.8%  38.2Ki [section .gnu.hash]          38.2Ki   0.1%
   0.7%  36.4Ki [section .eh_frame_hdr]      36.4Ki   0.1%
   0.0%       0 [section .debug_aranges]     27.6Ki   0.1%
   0.5%  26.4Ki [section .dynstr]            26.4Ki   0.1%
   0.0%       0 [section .symtab]            24.9Ki   0.1%
   0.4%  20.0Ki [section .data.rel.ro]       20.0Ki   0.1%
   0.0%       0 [section .debug_loc]         19.6Ki   0.1%
   0.3%  15.4Ki [section .dynsym]            15.4Ki   0.0%
 100.0%  4.91Mi TOTAL                        33.4Mi 100.0%

We can get an even richer report by combining the bloaty_package source with the original compileunits source:

$ ./bloaty -c config.bloaty -d bloaty_package,compileunits bloaty
     VM SIZE                                                                                    FILE SIZE
 --------------                                                                              --------------
  21.7%  1.06Mi third_party/protobuf                                                          14.2Mi  42.6%
      21.3%   232Ki third_party/protobuf/src/google/protobuf/descriptor.cc                        3.74Mi  26.3%
      25.9%   281Ki third_party/protobuf/src/google/protobuf/descriptor.pb.cc                     2.34Mi  16.5%
       6.8%  73.9Ki third_party/protobuf/src/google/protobuf/text_format.cc                        997Ki   6.9%
       7.7%  83.5Ki third_party/protobuf/src/google/protobuf/generated_message_reflection.cc       938Ki   6.4%
       2.9%  31.3Ki third_party/protobuf/src/google/protobuf/descriptor_database.cc                766Ki   5.3%
       4.7%  50.9Ki third_party/protobuf/src/google/protobuf/message.cc                            746Ki   5.1%
       4.4%  47.8Ki [14 Others]                                                                    686Ki   4.7%
       4.4%  48.3Ki third_party/protobuf/src/google/protobuf/extension_set.cc                      608Ki   4.2%
       4.3%  46.4Ki third_party/protobuf/src/google/protobuf/map_field.cc                          545Ki   3.7%
       3.8%  41.8Ki third_party/protobuf/src/google/protobuf/wire_format.cc                        513Ki   3.5%
       2.3%  25.4Ki third_party/protobuf/src/google/protobuf/generated_message_util.cc             511Ki   3.5%
       1.2%  12.9Ki third_party/protobuf/src/google/protobuf/dynamic_message.cc                    316Ki   2.2%
       1.6%  17.4Ki third_party/protobuf/src/google/protobuf/extension_set_heavy.cc                288Ki   2.0%
       2.3%  25.3Ki third_party/protobuf/src/google/protobuf/stubs/strutil.cc                      263Ki   1.8%
       1.2%  12.8Ki third_party/protobuf/src/google/protobuf/stubs/common.cc                       218Ki   1.5%
       1.5%  16.8Ki third_party/protobuf/src/google/protobuf/wire_format_lite.cc                   194Ki   1.3%
       0.8%  9.22Ki third_party/protobuf/src/google/protobuf/reflection_ops.cc                     183Ki   1.3%
       1.2%  12.9Ki third_party/protobuf/src/google/protobuf/io/tokenizer.cc                       162Ki   1.1%
       0.6%  6.90Ki third_party/protobuf/src/google/protobuf/unknown_field_set.cc                  150Ki   1.0%
       0.3%  3.00Ki third_party/protobuf/src/google/protobuf/any.cc                                117Ki   0.8%
       0.8%  9.15Ki third_party/protobuf/src/google/protobuf/message_lite.cc                       114Ki   0.8%
  42.4%  2.08Mi third_party/capstone                                                          6.88Mi  20.6%
      15.8%   335Ki third_party/capstone/arch/ARM/ARMDisassembler.c                               1.64Mi  23.8%
       4.7%   100Ki [22 Others]                                                                    579Ki   8.2%
       4.1%  86.9Ki third_party/capstone/arch/AArch64/AArch64Disassembler.c                        517Ki   7.3%
      15.4%   328Ki third_party/capstone/arch/X86/X86DisassemblerDecoder.c                         427Ki   6.1%
       6.5%   139Ki third_party/capstone/arch/AArch64/AArch64InstPrinter.c                         423Ki   6.0%
       2.6%  55.6Ki third_party/capstone/arch/Mips/MipsDisassembler.c                              408Ki   5.8%
      14.1%   299Ki third_party/capstone/arch/X86/X86Mapping.c                                     380Ki   5.4%
       3.5%  73.9Ki third_party/capstone/arch/ARM/ARMInstPrinter.c                                 293Ki   4.2%
       4.5%  96.6Ki third_party/capstone/arch/Sparc/SparcInstPrinter.c                             287Ki   4.1%
       0.7%  14.4Ki third_party/capstone/arch/X86/X86ATTInstPrinter.c                              276Ki   3.9%
       3.5%  74.8Ki third_party/capstone/arch/PowerPC/PPCInstPrinter.c                             273Ki   3.9%
       1.3%  27.8Ki third_party/capstone/arch/PowerPC/PPCDisassembler.c                            241Ki   3.4%
       1.2%  25.4Ki third_party/capstone/arch/SystemZ/SystemZDisassembler.c                        223Ki   3.2%
       0.6%  13.3Ki third_party/capstone/arch/X86/X86IntelInstPrinter.c                            187Ki   2.7%
       5.6%   118Ki third_party/capstone/arch/AArch64/AArch64Mapping.c                             154Ki   2.2%
       5.2%   111Ki third_party/capstone/arch/ARM/ARMMapping.c                                     148Ki   2.1%
       1.0%  20.3Ki third_party/capstone/arch/X86/X86Disassembler.c                                130Ki   1.9%
       3.8%  81.5Ki third_party/capstone/arch/Mips/MipsMapping.c                                   120Ki   1.7%
       0.5%  11.3Ki third_party/capstone/arch/XCore/XCoreDisassembler.c                            103Ki   1.5%
       3.3%  71.0Ki third_party/capstone/arch/PowerPC/PPCMapping.c                                 100Ki   1.4%
       2.1%  44.1Ki third_party/capstone/arch/SystemZ/SystemZMapping.c                            91.5Ki   1.3%
   5.1%   256Ki src                                                                           5.30Mi  15.9%
      35.3%  90.4Ki src/bloaty.cc                                                                 2.15Mi  40.7%
      24.9%  63.9Ki src/dwarf.cc                                                                  1.32Mi  25.0%
       1.7%  4.33Ki src/main.cc                                                                    483Ki   8.9%
      16.1%  41.3Ki src/bloaty.pb.cc                                                               465Ki   8.6%
      10.3%  26.3Ki src/elf.cc                                                                     397Ki   7.3%
       2.3%  5.81Ki src/disassemble.cc                                                             204Ki   3.8%
       3.2%  8.25Ki src/macho.cc                                                                   191Ki   3.5%
       6.3%  16.2Ki src/demangle.cc                                                                119Ki   2.2%
   5.5%   274Ki third_party/re2                                                               3.97Mi  11.9%
      13.3%  36.4Ki third_party/re2/re2/dfa.cc                                                     621Ki  15.3%
      15.4%  42.3Ki third_party/re2/re2/re2.cc                                                     618Ki  15.2%
      13.2%  36.1Ki third_party/re2/re2/regexp.cc                                                  538Ki  13.2%
       9.4%  25.7Ki third_party/re2/re2/compile.cc                                                 363Ki   9.0%
       7.0%  19.3Ki third_party/re2/re2/prog.cc                                                    341Ki   8.4%
      16.9%  46.2Ki third_party/re2/re2/parse.cc                                                   336Ki   8.3%
       8.6%  23.5Ki third_party/re2/re2/simplify.cc                                                298Ki   7.3%
       6.4%  17.5Ki third_party/re2/re2/nfa.cc                                                     267Ki   6.6%
       2.4%  6.52Ki third_party/re2/re2/tostring.cc                                                176Ki   4.3%
       2.5%  6.92Ki third_party/re2/re2/onepass.cc                                                 148Ki   3.7%
       3.2%  8.65Ki third_party/re2/re2/bitstate.cc                                                140Ki   3.4%
       0.0%       0 third_party/re2/re2/unicode_groups.cc                                         60.3Ki   1.5%
       0.0%       0 third_party/re2/re2/perl_groups.cc                                            41.1Ki   1.0%
       0.7%  1.94Ki third_party/re2/re2/stringpiece.cc                                            41.0Ki   1.0%
       0.8%  2.21Ki third_party/re2/util/strutil.cc                                               39.8Ki   1.0%
       0.0%       0 third_party/re2/re2/unicode_casefold.cc                                       26.3Ki   0.6%
       0.4%    1020 third_party/re2/util/rune.cc                                                  4.77Ki   0.1%
   1.6%  82.2Ki third_party/demumble                                                          1.17Mi   3.5%
     100.0%  82.2Ki third_party/demumble/third_party/libcxxabi/cxa_demangle.cpp                   1.17Mi 100.0%
   0.8%  38.0Ki third_party/abseil                                                             526Ki   1.5%
      26.5%  10.1Ki third_party/abseil-cpp/absl/strings/escaping.cc                                134Ki  25.6%
      24.6%  9.35Ki third_party/abseil-cpp/absl/strings/numbers.cc                                80.8Ki  15.4%
      11.5%  4.35Ki third_party/abseil-cpp/absl/strings/str_cat.cc                                58.9Ki  11.2%
      10.1%  3.84Ki third_party/abseil-cpp/absl/strings/string_view.cc                            44.2Ki   8.4%
       4.1%  1.55Ki third_party/abseil-cpp/absl/strings/str_split.cc                              41.6Ki   7.9%
       4.0%  1.51Ki third_party/abseil-cpp/absl/strings/ascii.cc                                  40.0Ki   7.6%
       3.4%  1.27Ki third_party/abseil-cpp/absl/strings/substitute.cc                             38.6Ki   7.3%
       9.3%  3.55Ki third_party/abseil-cpp/absl/base/internal/throw_delegate.cc                   38.2Ki   7.3%
       3.5%  1.33Ki third_party/abseil-cpp/absl/base/internal/raw_logging.cc                      31.9Ki   6.1%
       2.5%     985 third_party/abseil-cpp/absl/strings/internal/memutil.cc                       15.1Ki   2.9%
       0.6%     230 third_party/abseil-cpp/absl/strings/internal/utf8.cc                          1.85Ki   0.4%
   7.8%   390Ki [section .rodata]                                                              390Ki   1.1%
   6.4%   320Ki [section .rela.dyn]                                                            320Ki   0.9%
   4.6%   231Ki [section .eh_frame]                                                            231Ki   0.7%
   0.0%       0 [section .debug_str]                                                          82.7Ki   0.2%
   0.9%  44.8Ki [section .gcc_except_table]                                                   44.8Ki   0.1%
   0.0%       0 [section .strtab]                                                             40.5Ki   0.1%
   0.6%  31.5Ki [23 Others]                                                                   38.8Ki   0.1%
   0.8%  38.2Ki [section .gnu.hash]                                                           38.2Ki   0.1%
   0.7%  36.4Ki [section .eh_frame_hdr]                                                       36.4Ki   0.1%
   0.0%       0 [section .debug_aranges]                                                      27.6Ki   0.1%
   0.5%  26.4Ki [section .dynstr]                                                             26.4Ki   0.1%
   0.0%       0 [section .symtab]                                                             24.9Ki   0.1%
   0.4%  20.0Ki [section .data.rel.ro]                                                        20.0Ki   0.1%
   0.0%       0 [section .debug_loc]                                                          19.6Ki   0.1%
   0.3%  15.4Ki [section .dynsym]                                                             15.4Ki   0.0%
 100.0%  4.91Mi TOTAL                                                                         33.4Mi 100.0%

Future Work

Here are some tentative plans for future features.

Understanding Symbol References

If we can analyze references between symbols, this would enable a lot of features:

  • Detect garbage symbols (ie. how much would the binary shrink if we compiled with -ffunction-sections -fdata-sections -Wl,-gc-sections).
  • Understand why a particular symbol can't be garbage-collected (like ld -why_live on OS X).
  • Visualize the dependency tree of symbols (probably as a dominator tree) so users can see the weight of their binary in this way.

Improving the quality of data sources

One of the things we have to do in Bloaty is deal with incomplete information. For examples, .debug_aranges which we use for the compileunits data source is often missing or incomplete. Refining the input sources to be more complete and accurate will make help Bloaty's numbers be even more accurate.