llvm-project

d865f32f - [lldb] Parse DWARF CFI for discontinuous functions (#137006)

[lldb] Parse DWARF CFI for discontinuous functions (#137006) This patch uses the previously build infrastructure to parse multiple FDE entries into a single unwind plan. There is one catch though: we parse only one FDE entry per unwind range. This is not fully correct because lldb coalesces adjecant address ranges, which means that something that originally looked like two separate address ranges (and two FDE entries) may get merged into one because if the linker decides to put the two ranges next to each other. In this case, we will ignore the second FDE entry. It would be more correct to try to parse another entry when the one we found turns out to be short, but I'm not doing this (yet), because: - this is how we've done things so far (although, monolithic functions are unlikely to have more than one FDE entry) - in cases where we don't have debug info or (full) symbol tables, we can end up with "symbols" which appear to span many megabytes (potentially, the whole module). If we tried to fill short FDE entries, we could end up parsing the entire eh_frame section in a single go. In a way, this would be more correct, but it would also probably be very slow. I haven't quite decided what to do about this case yet, though it's not particularly likely to happen in the "production" cases as typically the functions are split into two parts (hot/cold) instead of one part per basic block.