[all-commits] [llvm/llvm-project] 6a07f1: debug_rnglists/symbolizing: reduce memory usage by...

[David Blaikie via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 6a07f1edf8e6a172734286cd3ab5988313313d8f
      https://github.com/llvm/llvm-project/commit/6a07f1edf8e6a172734286cd3ab5988313313d8f
  Author: David Blaikie <dblaikie at gmail.com>
  Date:   2020-09-16 (Wed, 16 Sep 2020)

  Changed paths:
    M llvm/include/llvm/DebugInfo/DWARF/DWARFListTable.h

  Log Message:
  -----------
  debug_rnglists/symbolizing: reduce memory usage by not caching rnglists

This matches the debug_ranges behavior - though is currently implemented
differently. (the debug_ranges parsing was handled by creating a new
ranges parser during DIE address querying, and just destroying it after
the query - whereas the rnglists parser is a member of the DWARFUnit
currently - so the API doesn't cache anymore)

I think this could/should be improved by not parsing debug_rnglists
headers at all when dumping debug_info or symbolizing - do it the way
DWARF (roughly) intended: take the rnglists_base, add addr*index to it,
read the offset, parse the list at rnglists_base+offset. This would have
no error checking for valid index (because the number of valid indexes
is stored in the header, which has a negative offset from rnglists_base
- and is sort of only intended for use by dumpers, not by parsers going
from debug_info to a rnglist) or out of contribution bounds access
(since it wouldn't know the length of the contribution, also in the
header) - nor any error-checking that the rnglist contribution was using
the same properties as the debug_info (version, DWARF32/64, address
size, etc).