Retrieval of the descriptor has to be performed in a single step. Finding out
what is missing and then downloading in bulk is not possible, as libbacktrace
caches the returned descriptors.
The code now performs a dry run of a dl_iterate_phdr call, storing the results
in a vector. Then, the original processing loop is issued, but outside of
dl_iterate_phdr.
For possible cause of problems see:
https://github.com/libunwind/libunwind/issues/16
Build identifiers stored in vectors are searched linearly. While not optimal,
this is enough for a basic implementation. In the future binary search option
may be explored, to see if it is worthwhile. Possible gains wouldn't be
significant, due to relatively small amount of debug info modules to handle.
Debug info descriptor requests that have not yet been checked for (i.e. not in
the s_di_known vector) are stored in the s_di_pending vector. When a check is
performed from within a libbacktrace callback handler, there are some unknown
problems with downloading data. Hence, the download process is delayed to be
performed at a later time. The debug info descriptors retrieval can be then
repeated.
Don't know exactly how to reproduce this. Nevertheless, the capture was
produced in an usual way. This may be dependant on the exact client
configuration.
/usr/lib/gcc/x86_64-linux-gnu/9/include/cpuid.h:223:1: error: redefinition of ‘unsigned int __get_cpuid_max(unsigned int, unsigned int*)’
In file included from ../../client/TracyProfiler.cpp:108,
from ../../TracyClient.cpp:23:
/usr/lib/gcc/x86_64-linux-gnu/9/include/cpuid.h:223:1: note: ‘unsigned int __get_cpuid_max(unsigned int, unsigned int*)’ previously defined here
Executing the "make db" will run the build process of the selected tool or
library through the bear wrapper (which has to be available in the system),
which will record the compilation parameters of each source file. This
database can be then used by VS Code to set the proper defines and find all
the required includes.
Note that database building is performed in context of the specific tool or
library. Not all tools have the same set of flags.
Bartosz Taudul
Blake Taylor