Dwz is a program that attempts to optimize DWARF debugging information
contained in ELF shared libraries and ELF executables for size, by
replacing DWARF information representation with equivalent smaller
representation where possible and by reducing the amount of duplication
using techniques from the DWARF standard appendix E - creating
DW_TAG_partial_unit compilation units (CUs) for duplicated information and using
DW_TAG_imported_unit to import it into each CU that needs it.

The tool handles DWARF 32-bit format debugging sections of versions
2, 3 and 4 and GNU extensions on top of those, though using DWARF 4
or worst case DWARF 3 is strongly recommended.

When not using the -m option (multifile mode), GDB CVS snapshot (soon to be
7.5) is sufficient, when using -m option, GDB from a git branch
http://sources.redhat.com/git/?p=archer.git;a=shortlog;h=refs/heads/archer-tromey-dwz-multifile
is needed.