Improve memory usage by reducing the lifetime of CTF types. Once a CTF
type has been converted to a (complete) LLDB type, there's no need to
keep it in memory anymore. For most types, we can free them right after
creating the corresponding LLDB types. The only exception is record
types, which are only completed lazily.
Differential revision: https://reviews.llvm.org/D156606
Support recursive record types in CTF, for example a struct that
contains a pointer to itself:
struct S {
struct S *n;
};
We are now more lazy when creating LLDB types. When encountering a
record type (struct or union) we create a forward declaration and only
complete it when requested.
Differential revision: https://reviews.llvm.org/D156498
Fix parsing of large structs. If the size of a struct exceeds a certain
threshold, the offset is encoded using two 32-bit integers instead of
one.
Differential revision: https://reviews.llvm.org/D156490
Separate parsing CTF and creating LLDB types. This is a prerequisite to
parsing forward references and recursive types.
Differential revision: https://reviews.llvm.org/D156447
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
