[PATCH] D50300: [WIP!][Dominators] Collect DomTree construction/update statistics and timing data

[Chijun Sima via Phabricator via llvm-commits]

NutshellySima created this revision.
NutshellySima added a reviewer: kuhar.
Herald added subscribers: llvm-commits, dexonsmith, mehdi_amini.

> Note: This is a work-in-progress patch and I don't intent to commit it.

This patch can work with https://reviews.llvm.org/D36884 to provide a better view to devs who concern about the performance of DomTree updating and construction.

This patch measures the performance of DomTree updating by counting via Statistics the number of no-ops/invalid updates removed, the number of lazy updates applied, the number of recalculation requested via the DomTreeUpdater interface.

This patch also provide timing data through the `Timer` and `TimerGroup` class in the LLVM codebase. I put the Timer of DominatorTree in the `DomTreeUpdater.cpp` because the Timer needs to be static and can only be initialized once so it cannot be in a header file. The unittests failed by this patch is because of some part of LLVM (e.g. `lto2`) is multithreaded.

Example data collected:

  $ opt -passes="default<O3>" -stats < ./sqlite.bc > /dev/null
  Statistics
      3 DTU-stats                    - Number of invalid updates discarded
   7058 DTU-stats                    - Number of lazy updates applied
   2541 DTU-stats                    - Number of no-ops removed
      3 DTU-stats                    - Number of recalculations requested
  ===-------------------------------------------------------------------------===
                                     DTU timing
  ===-------------------------------------------------------------------------===
    Total Execution Time: 0.0228 seconds (0.0230 wall clock)
  
     ---User Time---   --System Time--   --User+System--   ---Wall Time---  --- Name ---
     0.0223 ( 98.3%)   0.0001 ( 97.2%)   0.0224 ( 98.3%)   0.0227 ( 98.4%)  apply-updates -- DomTree
     0.0003 (  1.4%)   0.0000 (  2.8%)   0.0003 (  1.5%)   0.0003 (  1.3%)  apply-updates -- PostDomTree
     0.0000 (  0.1%)   0.0000 (  0.0%)   0.0000 (  0.1%)   0.0000 (  0.2%)  delete-edge -- DomTree
     0.0000 (  0.1%)   0.0000 (  0.0%)   0.0000 (  0.1%)   0.0000 (  0.1%)  insert-edge -- DomTree
     0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)  recalculate -- DomTree
     0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)  delete-edge -- PostDomTree
     0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)  insert-edge -- PostDomTree
     0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)  recalculate -- PostDomTree
     0.0227 (100.0%)   0.0001 (100.0%)   0.0228 (100.0%)   0.0230 (100.0%)  Total
  
  ===-------------------------------------------------------------------------===
                                DomTree Calculation
  ===-------------------------------------------------------------------------===
    Total Execution Time: 0.1437 seconds (0.1458 wall clock)
  
     ---User Time---   --System Time--   --User+System--   ---Wall Time---  --- Name ---
     0.0899 ( 63.4%)   0.0017 ( 88.4%)   0.0916 ( 63.8%)   0.0931 ( 63.9%)  recalculate -- DomTree
     0.0406 ( 28.6%)   0.0002 (  8.0%)   0.0408 ( 28.4%)   0.0409 ( 28.0%)  apply-updates -- DomTree
     0.0110 (  7.8%)   0.0001 (  3.4%)   0.0111 (  7.7%)   0.0116 (  8.0%)  recalculate -- PostDomTree
     0.0002 (  0.1%)   0.0000 (  0.2%)   0.0002 (  0.1%)   0.0002 (  0.1%)  delete-edge -- DomTree
     0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)   0.0000 (  0.0%)  insert-edge -- DomTree
     0.1417 (100.0%)   0.0019 (100.0%)   0.1437 (100.0%)   0.1458 (100.0%)  Total


Repository:
  rL LLVM

https://reviews.llvm.org/D50300

Files:
  include/llvm/IR/DomTreeUpdater.h
  include/llvm/Support/GenericDomTree.h
  lib/IR/DomTreeUpdater.cpp

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