Clone this repo:
  1. 3cf5c3f A bit more doc revision. by Joshua Haberman · 5 months ago master
  2. b784daf Some more doc revision. by Joshua Haberman · 5 months ago
  3. d764932 Tiny wordsmithing. by Joshua Haberman · 5 months ago
  4. 2862041 Merge branch 'master' of https://github.com/google/bloaty by Joshua Haberman · 5 months ago
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Bloaty McBloatface: a size profiler for binaries

Build Status

Ever wondered what‘s making your binary big? Bloaty McBloatface will show you a size profile of the binary so you can understand what’s taking up space inside.

Bloaty performs a deep analysis of the binary. Using custom ELF, DWARF, and Mach-O parsers, Bloaty aims to accurately attribute every byte of the binary to the symbol or compileunit that produced it. It will even disassemble the binary looking for references to anonymous data. For more information about the analysis performed by Bloaty, please see doc/how-bloaty-works.md.

Bloaty works on binaries, shared objects, object files, and static libraries (.a files). The following file formats are supported:

  • ELF
  • Mach-O
  • WebAssembly (experimental)

These formats are NOT supported, but I am very interested in adding support for them (I may implement these myself but would also be happy to get contributions!)

  • PE/COFF (not supported)
  • Android APK (not supported, might be tricky due to compression)

This is not an official Google product.

Building Bloaty

Building Bloaty requires CMake and protoc, the protobuf compiler. On Ubuntu, install them with:

$ sudo apt install cmake protobuf-compiler

Bloaty bundles libprotobuf, re2, capstone, and pkg-config as Git submodules, but it will prefer the system's versions of those dependencies if available. All other dependencies are included as Git submodules. To build, run:

$ cmake .
$ make -j6

To run tests (Git only, these are not included in the release tarball), 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:

$ ./bloaty bloaty
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  30.0%  8.85Mi   0.0%       0    .debug_info
  24.7%  7.29Mi   0.0%       0    .debug_loc
  12.8%  3.79Mi   0.0%       0    .debug_str
   9.7%  2.86Mi  42.8%  2.86Mi    .rodata
   6.9%  2.03Mi  30.3%  2.03Mi    .text
   6.3%  1.85Mi   0.0%       0    .debug_line
   4.0%  1.19Mi   0.0%       0    .debug_ranges
   0.0%       0  15.0%  1.01Mi    .bss
   1.6%   473Ki   0.0%       0    .strtab
   1.4%   435Ki   6.3%   435Ki    .data
   0.8%   254Ki   3.7%   254Ki    .eh_frame
   0.8%   231Ki   0.0%       0    .symtab
   0.5%   142Ki   0.0%       0    .debug_abbrev
   0.2%  56.8Ki   0.8%  56.8Ki    .gcc_except_table
   0.1%  41.4Ki   0.6%  41.4Ki    .eh_frame_hdr
   0.0%  11.4Ki   0.1%  9.45Ki    [26 Others]
   0.0%  7.20Ki   0.1%  7.14Ki    .dynstr
   0.0%  6.09Ki   0.1%  6.02Ki    .dynsym
   0.0%  4.89Ki   0.1%  4.83Ki    .rela.plt
   0.0%  4.59Ki   0.0%       0    [Unmapped]
   0.0%  3.30Ki   0.0%  3.23Ki    .plt
 100.0%  29.5Mi 100.0%  6.69Mi    TOTAL

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
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  34.8%  10.2Mi  43.4%  2.91Mi    [163 Others]
  17.2%  5.08Mi   4.3%   295Ki    third_party/protobuf/src/google/protobuf/descriptor.cc
   7.3%  2.14Mi   2.6%   179Ki    third_party/protobuf/src/google/protobuf/descriptor.pb.cc
   4.6%  1.36Mi   1.1%  78.4Ki    third_party/protobuf/src/google/protobuf/text_format.cc
   3.7%  1.10Mi   4.5%   311Ki    third_party/capstone/arch/ARM/ARMDisassembler.c
   1.3%   399Ki  15.9%  1.07Mi    third_party/capstone/arch/M68K/M68KDisassembler.c
   3.2%   980Ki   1.1%  75.3Ki    third_party/protobuf/src/google/protobuf/generated_message_reflection.cc
   3.2%   965Ki   0.6%  40.7Ki    third_party/protobuf/src/google/protobuf/descriptor_database.cc
   2.8%   854Ki  12.0%   819Ki    third_party/capstone/arch/X86/X86Mapping.c
   2.8%   846Ki   1.0%  66.4Ki    third_party/protobuf/src/google/protobuf/extension_set.cc
   2.7%   800Ki   0.6%  41.2Ki    third_party/protobuf/src/google/protobuf/generated_message_util.cc
   2.3%   709Ki   0.7%  50.7Ki    third_party/protobuf/src/google/protobuf/wire_format.cc
   2.1%   637Ki   1.7%   117Ki    third_party/demumble/third_party/libcxxabi/cxa_demangle.cpp
   1.8%   549Ki   1.7%   114Ki    src/bloaty.cc
   1.7%   503Ki   0.7%  48.1Ki    third_party/protobuf/src/google/protobuf/repeated_field.cc
   1.6%   469Ki   6.2%   427Ki    third_party/capstone/arch/X86/X86DisassemblerDecoder.c
   1.4%   434Ki   0.2%  15.9Ki    third_party/protobuf/src/google/protobuf/message.cc
   1.4%   422Ki   0.3%  23.4Ki    third_party/re2/re2/dfa.cc
   1.3%   407Ki   0.4%  24.9Ki    third_party/re2/re2/regexp.cc
   1.3%   407Ki   0.4%  29.9Ki    third_party/protobuf/src/google/protobuf/map_field.cc
   1.3%   397Ki   0.4%  24.8Ki    third_party/re2/re2/re2.cc
 100.0%  29.5Mi 100.0%  6.69Mi    TOTAL

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

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

USAGE: bloaty [OPTION]... FILE... [-- BASE_FILE...]

Options:

  --csv              Output in CSV format instead of human-readable.
  --tsv              Output in TSV format instead of human-readable.
  -c FILE            Load configuration from <file>.
  -d SOURCE,SOURCE   Comma-separated list of sources to scan.
  --debug-file=FILE  Use this file for debug symbols and/or symbol table.
  -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)
  --domain=DOMAIN    Which domains to show.  Possible values are:
                       --domain=vm
                       --domain=file
                       --domain=both (the default)
  -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.
  --source-filter=PATTERN
                     Only show keys with names matching this pattern.

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
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  80.7%  23.8Mi   0.0%       0    [Unmapped]
    37.2%  8.85Mi   NAN%       0    .debug_info
    30.6%  7.29Mi   NAN%       0    .debug_loc
    15.9%  3.79Mi   NAN%       0    .debug_str
     7.8%  1.85Mi   NAN%       0    .debug_line
     5.0%  1.19Mi   NAN%       0    .debug_ranges
     1.9%   473Ki   NAN%       0    .strtab
     1.0%   231Ki   NAN%       0    .symtab
     0.6%   142Ki   NAN%       0    .debug_abbrev
     0.0%  4.59Ki   NAN%       0    [Unmapped]
     0.0%     392   NAN%       0    .shstrtab
     0.0%     139   NAN%       0    .debug_macinfo
     0.0%      68   NAN%       0    .comment
  10.9%  3.21Mi  47.9%  3.21Mi    LOAD #4 [R]
    89.3%  2.86Mi  89.3%  2.86Mi    .rodata
     7.7%   254Ki   7.7%   254Ki    .eh_frame
     1.7%  56.8Ki   1.7%  56.8Ki    .gcc_except_table
     1.3%  41.4Ki   1.3%  41.4Ki    .eh_frame_hdr
     0.0%       1   0.0%       1    [LOAD #4 [R]]
   6.9%  2.03Mi  30.3%  2.03Mi    LOAD #3 [RX]
    99.8%  2.03Mi  99.8%  2.03Mi    .text
     0.2%  3.23Ki   0.2%  3.23Ki    .plt
     0.0%      28   0.0%      28    [LOAD #3 [RX]]
     0.0%      23   0.0%      23    .init
     0.0%       9   0.0%       9    .fini
   1.5%   439Ki  21.4%  1.44Mi    LOAD #5 [RW]
     0.0%       0  70.1%  1.01Mi    .bss
    99.1%   435Ki  29.6%   435Ki    .data
     0.4%  1.63Ki   0.1%  1.63Ki    .got.plt
     0.3%  1.46Ki   0.1%  1.46Ki    .data.rel.ro
     0.1%     560   0.0%     560    .dynamic
     0.1%     384   0.0%     376    .init_array
     0.0%      32   0.0%      56    [LOAD #5 [RW]]
     0.0%      32   0.0%      32    .got
     0.0%      16   0.0%      16    .tdata
     0.0%       8   0.0%       8    .fini_array
     0.0%       0   0.0%       8    .tbss
   0.1%  23.3Ki   0.3%  23.3Ki    LOAD #2 [R]
    30.7%  7.14Ki  30.7%  7.14Ki    .dynstr
    25.9%  6.02Ki  25.9%  6.02Ki    .dynsym
    20.8%  4.83Ki  20.8%  4.83Ki    .rela.plt
     7.7%  1.78Ki   7.7%  1.78Ki    .hash
     5.0%  1.17Ki   5.0%  1.17Ki    .rela.dyn
     3.1%     741   3.1%     741    [LOAD #2 [R]]
     2.7%     632   2.7%     632    .gnu.hash
     2.2%     514   2.2%     514    .gnu.version
     1.6%     384   1.6%     384    .gnu.version_r
     0.2%      36   0.2%      36    .note.gnu.build-id
     0.1%      32   0.1%      32    .note.ABI-tag
     0.1%      28   0.1%      28    .interp
   0.0%  2.56Ki   0.0%       0    [ELF Headers]
    46.3%  1.19Ki   NAN%       0    [19 Others]
     7.3%     192   NAN%       0    [ELF Headers]
     2.4%      64   NAN%       0    .comment
     2.4%      64   NAN%       0    .data
     2.4%      64   NAN%       0    .data.rel.ro
     2.4%      64   NAN%       0    .debug_abbrev
     2.4%      64   NAN%       0    .debug_info
     2.4%      64   NAN%       0    .debug_line
     2.4%      64   NAN%       0    .debug_loc
     2.4%      64   NAN%       0    .debug_macinfo
     2.4%      64   NAN%       0    .debug_ranges
     2.4%      64   NAN%       0    .debug_str
     2.4%      64   NAN%       0    .dynamic
     2.4%      64   NAN%       0    .dynstr
     2.4%      64   NAN%       0    .dynsym
     2.4%      64   NAN%       0    .eh_frame
     2.4%      64   NAN%       0    .eh_frame_hdr
     2.4%      64   NAN%       0    .fini
     2.4%      64   NAN%       0    .fini_array
     2.4%      64   NAN%       0    .gcc_except_table
     2.4%      64   NAN%       0    .gnu.hash
 100.0%  29.5Mi 100.0%  6.69Mi    TOTAL

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!).

If your binary has a build ID, then using separate debug files is as simple as:

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

Some format-specific notes follow.

ELF

For ELF, make sure you are compiling with build IDs enabled. With 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).

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.

Mach-O

Mach-O files always have build IDs (as far as I can tell), so no special configuration is needed to make sure you get them.

Mach-O puts debug information in separate files which you can create with dsymutil:

$ dsymutil bloaty
$ strip bloaty  (optional)
$ ./bloaty -d symbols --debug-file=bloaty.dSYM/Contents/Resources/DWARF/bloaty bloaty

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
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  80.7%  23.8Mi   0.0%       0    [Unmapped]
  10.9%  3.21Mi  47.9%  3.21Mi    LOAD #4 [R]
   6.9%  2.03Mi  30.3%  2.03Mi    LOAD #3 [RX]
   1.5%   439Ki  21.4%  1.44Mi    LOAD #5 [RW]
   0.1%  23.3Ki   0.3%  23.3Ki    LOAD #2 [R]
   0.0%  2.56Ki   0.0%       0    [ELF Headers]
 100.0%  29.5Mi 100.0%  6.69Mi    TOTAL

Here we see one segment mapped [RX] (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 -d segments CMakeFiles/libbloaty.dir/src/bloaty.cc.o
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  87.5%   972Ki   0.0%       0    Section []
   8.2%  90.9Ki  78.3%  90.9Ki    Section [AX]
   2.3%  25.2Ki  21.7%  25.2Ki    Section [A]
   2.0%  22.6Ki   0.0%       0    [ELF Headers]
   0.1%     844   0.0%       0    [Unmapped]
   0.0%      24   0.1%      72    Section [AW]
 100.0%  1.09Mi 100.0%   116Ki    TOTAL

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
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  30.0%  8.85Mi   0.0%       0    .debug_info
  24.7%  7.29Mi   0.0%       0    .debug_loc
  12.8%  3.79Mi   0.0%       0    .debug_str
   9.7%  2.86Mi  42.8%  2.86Mi    .rodata
   6.9%  2.03Mi  30.3%  2.03Mi    .text
   6.3%  1.85Mi   0.0%       0    .debug_line
   4.0%  1.19Mi   0.0%       0    .debug_ranges
   0.0%       0  15.0%  1.01Mi    .bss
   1.6%   473Ki   0.0%       0    .strtab
   1.4%   435Ki   6.3%   435Ki    .data
   0.8%   254Ki   3.7%   254Ki    .eh_frame
   0.8%   231Ki   0.0%       0    .symtab
   0.5%   142Ki   0.0%       0    .debug_abbrev
   0.2%  56.8Ki   0.8%  56.8Ki    .gcc_except_table
   0.1%  41.4Ki   0.6%  41.4Ki    .eh_frame_hdr
   0.0%  11.4Ki   0.1%  9.45Ki    [26 Others]
   0.0%  7.20Ki   0.1%  7.14Ki    .dynstr
   0.0%  6.09Ki   0.1%  6.02Ki    .dynsym
   0.0%  4.89Ki   0.1%  4.83Ki    .rela.plt
   0.0%  4.59Ki   0.0%       0    [Unmapped]
   0.0%  3.30Ki   0.0%  3.23Ki    .plt
 100.0%  29.5Mi 100.0%  6.69Mi    TOTAL

Sections are regions of the binary that are the linker treats as atomic when linking. The linker will never break apart or rearrange the data within a section. This is why it is necessary to compile with -ffunction-sections and -fdata-sections if you want the linker to strip out individual functions or variables that have no references. However the linker will often combine many input sections into a single output section.

Symbols

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

$ ./bloaty -d symbols bloaty
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  30.0%  8.85Mi   0.0%       0    [section .debug_info]
  24.7%  7.29Mi   0.0%       0    [section .debug_loc]
  12.8%  3.79Mi   0.0%       0    [section .debug_str]
  11.7%  3.44Mi  41.2%  2.76Mi    [5895 Others]
   6.3%  1.85Mi   0.0%       0    [section .debug_line]
   4.9%  1.43Mi  21.4%  1.43Mi    insns
   4.0%  1.19Mi   0.0%       0    [section .debug_ranges]
   0.0%      44  14.9%  1024Ki    g_instruction_table
   0.8%   255Ki   3.7%   255Ki    [section .rodata]
   0.8%   240Ki   3.5%   240Ki    printAliasInstr
   0.6%   175Ki   2.6%   175Ki    insn_ops
   0.5%   153Ki   2.2%   153Ki    ARMInsts
   0.5%   142Ki   0.0%       0    [section .debug_abbrev]
   0.5%   140Ki   2.0%   140Ki    x86DisassemblerTwoByteOpcodes
   0.4%   113Ki   1.6%   113Ki    insn_name_maps
   0.4%   106Ki   1.6%   106Ki    printInstruction.OpInfo
   0.3%  97.1Ki   1.4%  96.9Ki    printInstruction.OpInfo2
   0.2%  74.0Ki   1.1%  74.0Ki    x86DisassemblerThreeByte38Opcodes
   0.2%  71.1Ki   1.0%  70.8Ki    printInstruction.AsmStrs
   0.2%  61.1Ki   0.9%  60.9Ki    DecoderTable32
   0.2%  56.8Ki   0.8%  56.8Ki    [section .gcc_except_table]
 100.0%  29.5Mi 100.0%  6.69Mi    TOTAL

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 CMakeFiles/libbloaty.dir/src/*.o
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  42.8%  1.09Mi  37.9%   116Ki    CMakeFiles/libbloaty.dir/src/bloaty.cc.o
  15.7%   407Ki  15.5%  47.6Ki    CMakeFiles/libbloaty.dir/src/dwarf.cc.o
  10.3%   266Ki  10.4%  31.8Ki    CMakeFiles/libbloaty.dir/src/bloaty.pb.cc.o
   9.0%   232Ki   9.7%  29.8Ki    CMakeFiles/libbloaty.dir/src/elf.cc.o
   8.0%   207Ki   8.7%  26.6Ki    CMakeFiles/libbloaty.dir/src/macho.cc.o
   4.4%   114Ki   4.3%  13.1Ki    CMakeFiles/libbloaty.dir/src/webassembly.cc.o
   4.0%   103Ki   7.5%  22.9Ki    CMakeFiles/libbloaty.dir/src/demangle.cc.o
   3.4%  87.0Ki   3.3%  10.2Ki    CMakeFiles/libbloaty.dir/src/range_map.cc.o
   2.5%  64.3Ki   2.6%  7.94Ki    CMakeFiles/libbloaty.dir/src/disassemble.cc.o
 100.0%  2.53Mi 100.0%   306Ki    TOTAL

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 liblibbloaty.a
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  28.5%  1.21Mi  23.5%   120Ki    cxa_demangle.cpp.o
  25.6%  1.09Mi  22.6%   116Ki    bloaty.cc.o
   9.4%   407Ki   9.3%  47.6Ki    dwarf.cc.o
   6.2%   266Ki   6.2%  31.8Ki    bloaty.pb.cc.o
   5.4%   232Ki   5.8%  29.8Ki    elf.cc.o
   4.8%   207Ki   5.2%  26.6Ki    macho.cc.o
   2.6%   114Ki   2.6%  13.1Ki    webassembly.cc.o
   2.4%   103Ki   4.5%  22.9Ki    demangle.cc.o
   2.0%  87.0Ki   2.0%  10.2Ki    range_map.cc.o
   1.9%  80.4Ki   3.2%  16.7Ki    charconv_bigint.cc.o
   1.8%  79.3Ki   2.7%  14.0Ki    escaping.cc.o
   1.5%  65.0Ki   2.1%  10.9Ki    [9 Others]
   1.5%  64.3Ki   1.5%  7.94Ki    disassemble.cc.o
   1.4%  59.9Ki   0.0%       0    [AR Symbol Table]
   1.0%  45.2Ki   2.4%  12.4Ki    numbers.cc.o
   0.9%  40.9Ki   2.2%  11.4Ki    charconv.cc.o
   0.9%  38.8Ki   1.2%  6.10Ki    int128.cc.o
   0.7%  30.1Ki   1.1%  5.58Ki    str_cat.cc.o
   0.6%  24.1Ki   0.8%  3.92Ki    string_view.cc.o
   0.5%  21.2Ki   0.6%  3.21Ki    throw_delegate.cc.o
   0.4%  19.2Ki   0.4%  2.26Ki    ascii.cc.o
 100.0%  4.23Mi 100.0%   512Ki    TOTAL

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.

$ ./bloaty -d compileunits bloaty
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  34.8%  10.2Mi  43.4%  2.91Mi    [163 Others]
  17.2%  5.08Mi   4.3%   295Ki    third_party/protobuf/src/google/protobuf/descriptor.cc
   7.3%  2.14Mi   2.6%   179Ki    third_party/protobuf/src/google/protobuf/descriptor.pb.cc
   4.6%  1.36Mi   1.1%  78.4Ki    third_party/protobuf/src/google/protobuf/text_format.cc
   3.7%  1.10Mi   4.5%   311Ki    third_party/capstone/arch/ARM/ARMDisassembler.c
   1.3%   399Ki  15.9%  1.07Mi    third_party/capstone/arch/M68K/M68KDisassembler.c
   3.2%   980Ki   1.1%  75.3Ki    third_party/protobuf/src/google/protobuf/generated_message_reflection.cc
   3.2%   965Ki   0.6%  40.7Ki    third_party/protobuf/src/google/protobuf/descriptor_database.cc
   2.8%   854Ki  12.0%   819Ki    third_party/capstone/arch/X86/X86Mapping.c
   2.8%   846Ki   1.0%  66.4Ki    third_party/protobuf/src/google/protobuf/extension_set.cc
   2.7%   800Ki   0.6%  41.2Ki    third_party/protobuf/src/google/protobuf/generated_message_util.cc
   2.3%   709Ki   0.7%  50.7Ki    third_party/protobuf/src/google/protobuf/wire_format.cc
   2.1%   637Ki   1.7%   117Ki    third_party/demumble/third_party/libcxxabi/cxa_demangle.cpp
   1.8%   549Ki   1.7%   114Ki    src/bloaty.cc
   1.7%   503Ki   0.7%  48.1Ki    third_party/protobuf/src/google/protobuf/repeated_field.cc
   1.6%   469Ki   6.2%   427Ki    third_party/capstone/arch/X86/X86DisassemblerDecoder.c
   1.4%   434Ki   0.2%  15.9Ki    third_party/protobuf/src/google/protobuf/message.cc
   1.4%   422Ki   0.3%  23.4Ki    third_party/re2/re2/dfa.cc
   1.3%   407Ki   0.4%  24.9Ki    third_party/re2/re2/regexp.cc
   1.3%   407Ki   0.4%  29.9Ki    third_party/protobuf/src/google/protobuf/map_field.cc
   1.3%   397Ki   0.4%  24.8Ki    third_party/re2/re2/re2.cc
 100.0%  29.5Mi 100.0%  6.69Mi    TOTAL

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
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  30.0%  8.85Mi   0.0%       0    [section .debug_info]
  24.7%  7.29Mi   0.0%       0    [section .debug_loc]
  12.8%  3.79Mi   0.0%       0    [section .debug_str]
   9.7%  2.86Mi  42.8%  2.86Mi    [section .rodata]
   6.6%  1.96Mi  29.1%  1.95Mi    [44060 Others]
   6.3%  1.85Mi   0.0%       0    [section .debug_line]
   4.0%  1.19Mi   0.0%       0    [section .debug_ranges]
   0.0%       0  15.0%  1.01Mi    [section .bss]
   1.6%   473Ki   0.0%       0    [section .strtab]
   1.4%   435Ki   6.3%   435Ki    [section .data]
   0.8%   254Ki   3.7%   254Ki    [section .eh_frame]
   0.8%   231Ki   0.0%       0    [section .symtab]
   0.5%   142Ki   0.0%       0    [section .debug_abbrev]
   0.2%  56.8Ki   0.8%  56.8Ki    [section .gcc_except_table]
   0.1%  41.4Ki   0.6%  41.4Ki    [section .eh_frame_hdr]
   0.1%  27.4Ki   0.4%  27.4Ki    /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/basic_string.h:187
   0.1%  19.1Ki   0.3%  19.1Ki    /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/basic_string.h:183
   0.1%  16.8Ki   0.2%  16.8Ki    /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/ext/new_allocator.h:128
   0.1%  16.0Ki   0.2%  16.0Ki    /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/char_traits.h:300
   0.1%  15.8Ki   0.2%  15.8Ki    /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/basic_string.h:222
   0.0%  14.7Ki   0.2%  14.7Ki    [section .text]
 100.0%  29.5Mi 100.0%  6.69Mi    TOTAL

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
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  34.8%  10.2Mi  43.4%  2.91Mi    [163 Others]
  17.2%  5.08Mi   4.3%   295Ki    third_party/protobuf/src/google/protobuf/descriptor.cc
   7.3%  2.14Mi   2.6%   179Ki    third_party/protobuf/src/google/protobuf/descriptor.pb.cc
   4.6%  1.36Mi   1.1%  78.4Ki    third_party/protobuf/src/google/protobuf/text_format.cc
   3.7%  1.10Mi   4.5%   311Ki    third_party/capstone/arch/ARM/ARMDisassembler.c
   1.3%   399Ki  15.9%  1.07Mi    third_party/capstone/arch/M68K/M68KDisassembler.c
   3.2%   980Ki   1.1%  75.3Ki    third_party/protobuf/src/google/protobuf/generated_message_reflection.cc
   3.2%   965Ki   0.6%  40.7Ki    third_party/protobuf/src/google/protobuf/descriptor_database.cc
   2.8%   854Ki  12.0%   819Ki    third_party/capstone/arch/X86/X86Mapping.c
   2.8%   846Ki   1.0%  66.4Ki    third_party/protobuf/src/google/protobuf/extension_set.cc
   2.7%   800Ki   0.6%  41.2Ki    third_party/protobuf/src/google/protobuf/generated_message_util.cc
   2.3%   709Ki   0.7%  50.7Ki    third_party/protobuf/src/google/protobuf/wire_format.cc
   2.1%   637Ki   1.7%   117Ki    third_party/demumble/third_party/libcxxabi/cxa_demangle.cpp
   1.8%   549Ki   1.7%   114Ki    src/bloaty.cc
   1.7%   503Ki   0.7%  48.1Ki    third_party/protobuf/src/google/protobuf/repeated_field.cc
   1.6%   469Ki   6.2%   427Ki    third_party/capstone/arch/X86/X86DisassemblerDecoder.c
   1.4%   434Ki   0.2%  15.9Ki    third_party/protobuf/src/google/protobuf/message.cc
   1.4%   422Ki   0.3%  23.4Ki    third_party/re2/re2/dfa.cc
   1.3%   407Ki   0.4%  24.9Ki    third_party/re2/re2/regexp.cc
   1.3%   407Ki   0.4%  29.9Ki    third_party/protobuf/src/google/protobuf/map_field.cc
   1.3%   397Ki   0.4%  24.8Ki    third_party/re2/re2/re2.cc
 100.0%  29.5Mi 100.0%  6.69Mi    TOTAL

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.

$ cat bloaty_package.bloaty
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 bloaty_package.bloaty -d bloaty_package bloaty
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  56.6%  16.7Mi  16.6%  1.11Mi    third_party/protobuf
  24.9%  7.35Mi  68.5%  4.58Mi    third_party/capstone
   9.4%  2.77Mi   3.2%   221Ki    third_party/re2
   4.6%  1.36Mi   4.1%   280Ki    src
   2.1%   637Ki   1.7%   117Ki    third_party/demumble
   0.7%   209Ki   1.1%  73.8Ki    third_party/abseil
   0.7%   204Ki   3.0%   204Ki    [section .rodata]
   0.2%  56.8Ki   0.8%  56.8Ki    [section .gcc_except_table]
   0.2%  47.7Ki   0.0%       0    [section .debug_str]
   0.2%  46.3Ki   0.0%       0    [section .symtab]
   0.1%  42.0Ki   0.6%  42.0Ki    [section .text]
   0.1%  41.4Ki   0.0%       0    [section .debug_loc]
   0.1%  29.3Ki   0.0%       0    [section .strtab]
   0.0%  12.0Ki   0.2%  11.5Ki    [30 Others]
   0.0%  7.36Ki   0.0%       0    [section .debug_ranges]
   0.0%  6.10Ki   0.1%  6.10Ki    [section .dynstr]
   0.0%  4.99Ki   0.1%  4.99Ki    [section .dynsym]
   0.0%  4.77Ki   0.1%  4.77Ki    [section .eh_frame]
   0.0%  4.59Ki   0.0%       0    [Unmapped]
   0.0%  3.23Ki   0.0%  3.23Ki    [section .plt]
   0.0%  2.50Ki   0.0%       0    [ELF Headers]
 100.0%  29.5Mi 100.0%  6.69Mi    TOTAL

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
    FILE SIZE        VM SIZE    
 --------------  -------------- 
  56.6%  16.7Mi  16.6%  1.11Mi    third_party/protobuf
    30.5%  5.08Mi  26.0%   295Ki    third_party/protobuf/src/google/protobuf/descriptor.cc
    12.8%  2.14Mi  15.8%   179Ki    third_party/protobuf/src/google/protobuf/descriptor.pb.cc
     8.2%  1.36Mi   6.9%  78.4Ki    third_party/protobuf/src/google/protobuf/text_format.cc
     5.7%   980Ki   6.6%  75.3Ki    third_party/protobuf/src/google/protobuf/generated_message_reflection.cc
     5.7%   965Ki   3.6%  40.7Ki    third_party/protobuf/src/google/protobuf/descriptor_database.cc
     5.0%   846Ki   5.8%  66.4Ki    third_party/protobuf/src/google/protobuf/extension_set.cc
     4.7%   800Ki   3.6%  41.2Ki    third_party/protobuf/src/google/protobuf/generated_message_util.cc
     4.7%   798Ki   6.1%  69.3Ki    [16 Others]
     4.2%   709Ki   4.5%  50.7Ki    third_party/protobuf/src/google/protobuf/wire_format.cc
     2.9%   503Ki   4.2%  48.1Ki    third_party/protobuf/src/google/protobuf/repeated_field.cc
     2.5%   434Ki   1.4%  15.9Ki    third_party/protobuf/src/google/protobuf/message.cc
     2.4%   407Ki   2.6%  29.9Ki    third_party/protobuf/src/google/protobuf/map_field.cc
     1.8%   309Ki   2.4%  27.5Ki    third_party/protobuf/src/google/protobuf/stubs/strutil.cc
     1.5%   256Ki   0.8%  9.19Ki    third_party/protobuf/src/google/protobuf/dynamic_message.cc
     1.2%   208Ki   1.2%  13.2Ki    third_party/protobuf/src/google/protobuf/extension_set_heavy.cc
     1.2%   206Ki   2.4%  27.4Ki    third_party/protobuf/src/google/protobuf/wire_format_lite.cc
     1.1%   192Ki   1.6%  17.7Ki    third_party/protobuf/src/google/protobuf/parse_context.cc
     1.1%   187Ki   0.8%  9.33Ki    third_party/protobuf/src/google/protobuf/reflection_ops.cc
     1.0%   167Ki   1.2%  13.9Ki    third_party/protobuf/src/google/protobuf/message_lite.cc
     1.0%   165Ki   1.6%  18.7Ki    third_party/protobuf/src/google/protobuf/io/tokenizer.cc
     0.9%   152Ki   0.7%  7.57Ki    third_party/protobuf/src/google/protobuf/unknown_field_set.cc
  24.9%  7.35Mi  68.5%  4.58Mi    third_party/capstone
    17.4%  1.28Mi   6.5%   303Ki    [38 Others]
    14.9%  1.10Mi   6.6%   311Ki    third_party/capstone/arch/ARM/ARMDisassembler.c
     5.3%   399Ki  23.3%  1.07Mi    third_party/capstone/arch/M68K/M68KDisassembler.c
    11.4%   854Ki  17.5%   819Ki    third_party/capstone/arch/X86/X86Mapping.c
     6.2%   469Ki   9.1%   427Ki    third_party/capstone/arch/X86/X86DisassemblerDecoder.c
     4.8%   363Ki   1.3%  59.1Ki    third_party/capstone/arch/SystemZ/SystemZDisassembler.c
     4.4%   329Ki   1.2%  54.2Ki    third_party/capstone/arch/Mips/MipsDisassembler.c
     4.2%   314Ki   1.6%  73.0Ki    third_party/capstone/arch/AArch64/AArch64Disassembler.c
     3.4%   256Ki   3.1%   145Ki    third_party/capstone/arch/AArch64/AArch64InstPrinter.c
     3.2%   243Ki   4.7%   219Ki    third_party/capstone/arch/AArch64/AArch64Mapping.c
     3.2%   241Ki   4.7%   220Ki    third_party/capstone/arch/SystemZ/SystemZMapping.c
     2.9%   219Ki   4.2%   196Ki    third_party/capstone/arch/ARM/ARMMapping.c
     2.7%   205Ki   1.8%  83.3Ki    third_party/capstone/arch/ARM/ARMInstPrinter.c
     2.2%   166Ki   2.0%  95.4Ki    third_party/capstone/arch/PowerPC/PPCInstPrinter.c
     2.0%   153Ki   2.8%   132Ki    third_party/capstone/arch/Mips/MipsMapping.c
     2.0%   153Ki   0.4%  17.7Ki    third_party/capstone/arch/TMS320C64x/TMS320C64xDisassembler.c
     2.0%   151Ki   2.1%  99.0Ki    third_party/capstone/arch/X86/X86ATTInstPrinter.c
     2.0%   149Ki   1.9%  90.6Ki    third_party/capstone/arch/Sparc/SparcInstPrinter.c
     2.0%   148Ki   2.7%   126Ki    third_party/capstone/arch/PowerPC/PPCMapping.c
     1.9%   146Ki   2.1%  96.2Ki    third_party/capstone/arch/X86/X86IntelInstPrinter.c
     1.7%   124Ki   0.6%  28.7Ki    third_party/capstone/arch/PowerPC/PPCDisassembler.c
   9.4%  2.77Mi   3.2%   221Ki    third_party/re2
    14.9%   422Ki  10.6%  23.4Ki    third_party/re2/re2/dfa.cc
    14.4%   407Ki  11.3%  24.9Ki    third_party/re2/re2/regexp.cc
    14.0%   397Ki  11.2%  24.8Ki    third_party/re2/re2/re2.cc
    12.2%   345Ki  10.0%  22.1Ki    third_party/re2/re2/prog.cc
    11.4%   322Ki  33.1%  73.2Ki    third_party/re2/re2/parse.cc
    10.3%   292Ki   8.9%  19.6Ki    third_party/re2/re2/compile.cc
     5.6%   159Ki   3.7%  8.08Ki    third_party/re2/re2/nfa.cc
     4.6%   130Ki   4.7%  10.5Ki    third_party/re2/re2/simplify.cc
     3.7%   106Ki   1.9%  4.19Ki    third_party/re2/re2/onepass.cc
     3.1%  88.7Ki   1.4%  3.08Ki    third_party/re2/re2/bitstate.cc
     2.9%  83.6Ki   1.6%  3.50Ki    third_party/re2/re2/tostring.cc
     1.1%  31.3Ki   0.6%  1.41Ki    third_party/re2/re2/stringpiece.cc
     0.9%  24.3Ki   0.6%  1.22Ki    third_party/re2/util/strutil.cc
     0.6%  16.2Ki   0.0%       0    third_party/re2/re2/unicode_groups.cc
     0.2%  5.36Ki   0.5%  1.09Ki    third_party/re2/util/rune.cc
     0.1%  1.50Ki   0.0%       0    third_party/re2/re2/perl_groups.cc
     0.0%     661   0.0%       0    third_party/re2/re2/unicode_casefold.cc
   4.6%  1.36Mi   4.1%   280Ki    src
    39.4%   549Ki  40.7%   114Ki    src/bloaty.cc
    13.9%   193Ki  15.0%  42.1Ki    src/dwarf.cc
    10.8%   150Ki   0.5%  1.28Ki    src/main.cc
     8.1%   113Ki   8.9%  25.0Ki    src/bloaty.pb.cc
     7.7%   108Ki   9.0%  25.2Ki    src/elf.cc
     7.2%  99.9Ki  10.3%  29.0Ki    src/macho.cc
     4.7%  66.2Ki   7.0%  19.5Ki    src/demangle.cc
     3.5%  49.5Ki   3.8%  10.5Ki    src/webassembly.cc
     2.8%  38.8Ki   2.7%  7.50Ki    src/range_map.cc
     1.9%  26.2Ki   2.1%  5.98Ki    src/disassemble.cc
   2.1%   637Ki   1.7%   117Ki    third_party/demumble
   100.0%   637Ki 100.0%   117Ki    third_party/demumble/third_party/libcxxabi/cxa_demangle.cpp
   0.7%   209Ki   1.1%  73.8Ki    third_party/abseil
    19.0%  39.8Ki  19.0%  14.0Ki    third_party/abseil-cpp/absl/strings/internal/charconv_bigint.cc
    15.6%  32.6Ki  13.6%  10.1Ki    third_party/abseil-cpp/absl/strings/escaping.cc
    14.9%  31.1Ki  25.0%  18.5Ki    third_party/abseil-cpp/absl/strings/charconv.cc
    12.3%  25.7Ki  10.6%  7.79Ki    third_party/abseil-cpp/absl/numeric/int128.cc
     8.5%  17.9Ki   9.0%  6.65Ki    third_party/abseil-cpp/absl/strings/numbers.cc
     6.8%  14.3Ki   5.2%  3.87Ki    third_party/abseil-cpp/absl/strings/str_cat.cc
     6.1%  12.7Ki   5.1%  3.75Ki    third_party/abseil-cpp/absl/strings/string_view.cc
     3.6%  7.49Ki   1.7%  1.23Ki    third_party/abseil-cpp/absl/strings/ascii.cc
     2.9%  6.10Ki   3.5%  2.56Ki    third_party/abseil-cpp/absl/strings/internal/charconv_parse.cc
     2.7%  5.75Ki   1.5%  1.13Ki    third_party/abseil-cpp/absl/strings/str_split.cc
     2.3%  4.84Ki   1.9%  1.40Ki    third_party/abseil-cpp/absl/strings/substitute.cc
     1.4%  3.03Ki   1.0%     754    third_party/abseil-cpp/absl/base/internal/raw_logging.cc
     1.1%  2.28Ki   0.4%     302    third_party/abseil-cpp/absl/base/internal/throw_delegate.cc
     0.9%  1.97Ki   1.0%     788    third_party/abseil-cpp/absl/strings/internal/memutil.cc
     0.9%  1.93Ki   0.9%     701    third_party/abseil-cpp/absl/strings/internal/escaping.cc
     0.7%  1.41Ki   0.4%     293    third_party/abseil-cpp/absl/strings/match.cc
     0.3%     556   0.2%     161    third_party/abseil-cpp/absl/strings/internal/utf8.cc
   0.7%   204Ki   3.0%   204Ki    [section .rodata]
   0.2%  56.8Ki   0.8%  56.8Ki    [section .gcc_except_table]
   0.2%  47.7Ki   0.0%       0    [section .debug_str]
   0.2%  46.3Ki   0.0%       0    [section .symtab]
   0.1%  42.0Ki   0.6%  42.0Ki    [section .text]
   0.1%  41.4Ki   0.0%       0    [section .debug_loc]
   0.1%  29.3Ki   0.0%       0    [section .strtab]
   0.0%  12.0Ki   0.2%  11.5Ki    [30 Others]
   0.0%  7.36Ki   0.0%       0    [section .debug_ranges]
   0.0%  6.10Ki   0.1%  6.10Ki    [section .dynstr]
   0.0%  4.99Ki   0.1%  4.99Ki    [section .dynsym]
   0.0%  4.77Ki   0.1%  4.77Ki    [section .eh_frame]
   0.0%  4.59Ki   0.0%       0    [Unmapped]
   0.0%  3.23Ki   0.0%  3.23Ki    [section .plt]
   0.0%  2.50Ki   0.0%       0    [ELF Headers]
 100.0%  29.5Mi 100.0%  6.69Mi    TOTAL

Source filter

Sometimes, you are only interested in parts of the binary instead of the whole package. This is common in embedded programming, where ELF files are used only as a container format, and only a few sections are actually loaded onto the device.

For this, Bloaty provides a --source-filter option which allows filtering out irrelevant data. It takes a regex which is applied to each of the symbol names in a data source. Only symbols which match the regex are displayed in the output. This is especially powerful when combined with custom data sources, as the rewriting occurs before the filtering.

In the case of hierarchical data source profiles, the regex is applied to all symbol names in the hierarchy. If any name matches, all of its parents will be displayed as well.

For example, given the above scenario, maybe we are only interested in how large the first-party Bloaty code is. This can be displayed using a source filter on the src directory.

$ ./bloaty -c config.bloaty -d bloaty_package,compileunits --source-filter ^src bloaty
    FILE SIZE        VM SIZE    
 --------------  -------------- 
 100.0%  1.36Mi 100.0%   280Ki    src
    39.4%   549Ki  40.7%   114Ki    src/bloaty.cc
    13.9%   193Ki  15.0%  42.1Ki    src/dwarf.cc
    10.8%   150Ki   0.5%  1.28Ki    src/main.cc
     8.1%   113Ki   8.9%  25.0Ki    src/bloaty.pb.cc
     7.7%   108Ki   9.0%  25.2Ki    src/elf.cc
     7.2%  99.9Ki  10.3%  29.0Ki    src/macho.cc
     4.7%  66.2Ki   7.0%  19.5Ki    src/demangle.cc
     3.5%  49.5Ki   3.8%  10.5Ki    src/webassembly.cc
     2.8%  38.8Ki   2.7%  7.50Ki    src/range_map.cc
     1.9%  26.2Ki   2.1%  5.98Ki    src/disassemble.cc
 100.0%  1.36Mi 100.0%   280Ki    TOTAL
Filtering enabled (source_filter); omitted file = 28.1Mi, vm = 6.42Mi of entries

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.