[PATCH] D54361: [ELF] .gdb_index: fix CuOff when a .debug_info section contains more than 1 CU

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added inline comments.


================
Comment at: lld/trunk/ELF/SyntheticSections.cpp:2432
+      //
+      // We assume both CUs[*].CuOff and Set.Offset are increasing.
+      while (I < CUs.size() && CUs[I].CuOffset < Set.Offset)
----------------
dblaikie wrote:
> Could you fix this? This assumption seems pretty subtle/likely to break valid DWARF in surprising/hard to diagnose ways.
> 
> Moving the declaration of I into the for(Set) loop (ie: putting it just before this while loop) should suffice - and a test case with 2 pubnames in the reverse order to CUs would demonstrate the fix?
> 
> (would be nice to do a binary search rather than a linear one on the CU offsets, since they are naturally sorted by offset)
> 
> 
I used `std::lower_bound(CUs.begin(), CUs.end(), ...) - CUs.begin())` in a former version but  @ruiu thought it was too complicated...


Repository:
  rL LLVM

https://reviews.llvm.org/D54361