[PATCH] D74169: [WIP][LLD][ELF][DebugInfo] Remove obsolete debug info.

[Alexey Lapshin via Phabricator via llvm-commits]

avl added a comment.

Re-measured size/performance results:

A: --function-sections --gc-sections 
B: --function-sections --gc-sections --gc-debuginfo
C: --function-sections --gc-sections --fdebug-types-section
D: --function-sections --gc-sections --gsplit-dwarf
E: --function-sections --gc-sections --fdebug-types-section --gc-debuginfo
(last case does not produce valid DWARF currently)

  LLVM code base:
  --------------------------------------------------------------
  | Options |    build time   |    bin size   |    lib size    | 
  --------------------------------------------------------------
  |    A    |    66min(100%)  |   18.0G(100%) |  16.0G(100.0%) |
  --------------------------------------------------------------
  |    B    |    81min(123%)  |    9.7G( 54%) |  13.0G( 81.0%) |
  --------------------------------------------------------------
  |    C    |    58min( 87%)  |   12.0G( 67%) |  15.0G( 93.5%) |
  --------------------------------------------------------------
  |    D    |    58min( 87%)  |   12.0G( 67%) |   8.7G( 54.0%) |
  --------------------------------------------------------------
  |    E    |    68min(103%)  |    7.6G( 42%) |  14.0G( 87.5%) |
  --------------------------------------------------------------
  
  
  Clang binary:
  --------------------------------------------------------------
  | Options |       size     |     link time   |  used memory  |
  --------------------------------------------------------------
  |    A    |    1.50G(100%) |   26.7sec(100%) |  9191MB(100%) |
  --------------------------------------------------------------
  |    B    |    0.76G( 50%) |  107.4sec(402%) | 13361MB(145%) |
  --------------------------------------------------------------
  |    C    |    0.82G( 54%) |   18.3sec( 68%) |  8300MB( 90%) |
  --------------------------------------------------------------
  |    D    |    0.96G( 64%) |    7.6sec( 28%) |  4255MB( 46%) |
  --------------------------------------------------------------
  |    E    |    0.58G( 45%) |   58.5sec(219%) | 10317MB(112%) |
  --------------------------------------------------------------
  
  
  lldb loading time:
  ---------------------------------------------
  | Options |       time     |   used memory  |
  ---------------------------------------------
  |    A    |  6.32sec(100%) |  1475MB(100%)  |
  ---------------------------------------------
  |    B    |  3.49sec( 55%) |   825MB( 56%)  |
  ---------------------------------------------
  |    C    |  3.65sec( 58%) |   875MB( 59%)  |
  ---------------------------------------------
  |    D    |  4.12sec( 65%) |  1017MB( 69%)  |
  ---------------------------------------------
  |    E    |  3.95sec( 63%) |   628MB( 43%)  |
  ---------------------------------------------


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  https://reviews.llvm.org/D74169/new/

https://reviews.llvm.org/D74169