Debugging stripped MachO binaries? about bloaty HOT 5 CLOSED

Thanks for the kind words about Bloaty!

I need to implement this. You're right that the existing info is all for ELF.

Mach-O gets build IDs by default in the LC_UUID load command. No special flag is required. It should be relatively simple to make this work by implementing MachOObjectFile::GetBuildId() to read this id.

We could go further and try to automatically find the debug info file, running dsymutil if we can't find it. But for now I'll just implement the simple thing.

from bloaty.

Thanks for #133. I'm a bit confused by this TODO though. Without DWARF support, it's still not possible to profile a stripped MachO binary via the .dSYM, right?

from bloaty.

You can use a symbol table from a non-stripped binary to profile a stripped binary. This is what is documented above that TODO, and it works for both ELF and Mach-O. It doesn't require .dSYM files.

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

from bloaty.

Unfortunately dsymutil doesn't appear to put a full symbol table in the .dSYM file, so I don't think this technique will work via dsymutil.

from bloaty.

I take it back, dsymutil does appear to put a symbol table in .dSYM. This works as expected:

$ strip bloaty
$ dsymutil bloaty
$ $ ./bloaty --debug-file bloaty.dSYM/Contents/Resources/DWARF/bloaty  bloaty -d symbols

I should update the docs accordingly. Maybe this means I can also enable -d compileunits for Mach-O!

from bloaty.