To make this work this patch extends LLDB to:
- Explicitly track the link_map address for each module. This is effectively the module handle, not sure why it wasn't already being stored off anywhere. As an extension later, it would be nice if someone were to add support for printing this as part of the modules list.
- Allow reading the per-thread data pointer via ptrace. I have added support for Linux here. I'll be happy to add support for FreeBSD once this is reviewed. OS X does not appear to have __thread variables, so maybe we don't need it there. Windows support should eventually be workable along the same lines.
- Make DWARF expressions track which module they originated from.
- Add support for the DW_OP_GNU_push_tls_address DWARF opcode, as generated by gcc and recent versions of clang. Earlier versions of clang (such as 3.2, which is default on Ubuntu right now) do not generate TLS debug info correctly so can not be supported here.
- Understand the format of the pthread DTV block. This is where it gets tricky. We have three basic options here:
1) Call "dlinfo" or "__tls_get_addr" on the inferior and ask it directly. However this won't work on core dumps, and generally speaking it's not a good idea for the debugger to call functions itself, as it has the potential to not work depending on the state of the target.
2) Use libthread_db. This is what GDB does. However this option requires having a version of libthread_db on the host cross-compiled for each potential target. This places a large burden on the user, and would make it very hard to cross-debug from Windows to Linux, for example. Trying to build a library intended exclusively for one OS on a different one is not pleasant. GDB sidesteps the problem and asks the user to figure it out.
3) Parse the DTV structure ourselves. On initial inspection this seems to be a bad option, as the DTV structure (the format used by the runtime to manage TLS data) is not in fact a kernel data structure, it is implemented entirely in useerland in libc. Therefore the layout of it's fields are version and OS dependent, and are not standardized.
However, it turns out not to be such a problem. All OSes use basically the same algorithm (a per-module lookup table) as detailed in Ulrich Drepper's TLS ELF ABI document, so we can easily write code to decode it ourselves. The only question therefore is the exact field layouts required. Happily, the implementors of libpthread expose the structure of the DTV via metadata exported as symbols from the .so itself, designed exactly for this kind of thing. So this patch simply reads that metadata in, and re-implements libthread_db's algorithm itself. We thereby get cross-platform TLS lookup without either requiring third-party libraries, while still being independent of the version of libpthread being used.
Test case included.
llvm-svn: 192922
On at least FreeBSD and NetBSD there is an extra field in the dyld link
map struct. I've left an assert for other OSes (i.e., Linux/mips) until
it's determined if they do the same.
llvm-svn: 192358
LLDB is crashing when logging is enabled from lldb-perf-clang. This has to do with the global destructor chain as the process and its threads are being torn down.
All logging channels now make one and only one instance that is kept in a global pointer which is never freed. This guarantees that logging can correctly continue as the process tears itself down.
llvm-svn: 178191
Major fixed to allow reading files that are over 4GB. The main problems were that the DataExtractor was using 32 bit offsets as a data cursor, and since we mmap all of our object files we could run into cases where if we had a very large core file that was over 4GB, we were running into the 4GB boundary.
So I defined a new "lldb::offset_t" which should be used for all file offsets.
After making this change, I enabled warnings for data loss and for enexpected implicit conversions temporarily and found a ton of things that I fixed.
Any functions that take an index internally, should use "size_t" for any indexes and also should return "size_t" for any sizes of collections.
llvm-svn: 173463
Make breakpoint setting by file and line much more efficient by only looking for inlined breakpoint locations if we are setting a breakpoint in anything but a source implementation file. Implementing this complex for a many reasons. Turns out that parsing compile units lazily had some issues with respect to how we need to do things with DWARF in .o files. So the fixes in the checkin for this makes these changes:
- Add a new setting called "target.inline-breakpoint-strategy" which can be set to "never", "always", or "headers". "never" will never try and set any inlined breakpoints (fastest). "always" always looks for inlined breakpoint locations (slowest, but most accurate). "headers", which is the default setting, will only look for inlined breakpoint locations if the breakpoint is set in what are consudered to be header files, which is realy defined as "not in an implementation source file".
- modify the breakpoint setting by file and line to check the current "target.inline-breakpoint-strategy" setting and act accordingly
- Modify compile units to be able to get their language and other info lazily. This allows us to create compile units from the debug map and not have to fill all of the details in, and then lazily discover this information as we go on debuggging. This is needed to avoid parsing all .o files when setting breakpoints in implementation only files (no inlines). Otherwise we would need to parse the .o file, the object file (mach-o in our case) and the symbol file (DWARF in the object file) just to see what the compile unit was.
- modify the "SymbolFileDWARFDebugMap" to subclass lldb_private::Module so that the virtual "GetObjectFile()" and "GetSymbolVendor()" functions can be intercepted when the .o file contenst are later lazilly needed. Prior to this fix, when we first instantiated the "SymbolFileDWARFDebugMap" class, we would also make modules, object files and symbol files for every .o file in the debug map because we needed to fix up the sections in the .o files with information that is in the executable debug map. Now we lazily do this in the DebugMapModule::GetObjectFile()
Cleaned up header includes a bit as well.
llvm-svn: 162860
so that we don't break it with code changes.
After doing this I was able to fix the POSIX-DYLD plug-in so that it builds
after recent ModuleSpec changes.
llvm-svn: 151536
This patch combines common code from Linux and FreeBSD into
a new POSIX platform. It also contains fixes for 64bit FreeBSD.
The patch is based on changes by Mark Peek <mp@FreeBSD.org> and
"K. Macy" <kmacy@freebsd.org> in their github repo located at
https://github.com/fbsd/lldb.
llvm-svn: 147613
Richard Mitton