Add support for compressed CTF data. The flags in the header can
indicate whether the CTF body is compressed with zlib deflate. This
patch supports inflating the data before parsing.
Differential revision: https://reviews.llvm.org/D155221
Add support for the Compact C Type Format (CTF) in LLDB. The format
describes the layout and sizes of C types. It is most commonly consumed
by dtrace.
We generate CTF for the XNU kernel and want to be able to use this in
LLDB to debug kernels for which we don't have dSYMs (anymore). CTF is a
much more limited debug format than DWARF which allows is to be an order
of magnitude smaller: a 1GB dSYM can be converted to a handful of
megabytes of CTF. For XNU, the goal is not to replace DWARF, but rather
to have CTF serve as a "better than nothing" debug info format when
DWARF is not available.
It's worth noting that the LLVM toolchain does not support emitting CTF.
XNU uses ctfconvert to generate CTF from DWARF which is used for
testing.
Differential revision: https://reviews.llvm.org/D154862
