[all-commits] [llvm/llvm-project] 4cc20a: [DSE, MemorySSA] Skip access already dominated by a...

[Florian Hahn via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 4cc20aa74339812c3e4daa4138ed40cb98521bfc
      https://github.com/llvm/llvm-project/commit/4cc20aa74339812c3e4daa4138ed40cb98521bfc
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2020-08-17 (Mon, 17 Aug 2020)

  Changed paths:
    M llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp

  Log Message:
  -----------
  [DSE,MemorySSA] Skip access already dominated by a killing def.

If we already found a killing def (= a def that completely overwrites
the location) that dominates an access, we can skip processing it
further.

This does not help with compile-time, but increases the number of memory
accesses we can process with the same scan budget, leading to more
stores being eliminated.

Improvements with this change

Same hash: 203 (filtered out)
Remaining: 34
Metric: dse.NumFastStores

Program                                        base    dom     diff
 test-suite...rolangs-C++/family/family.test     2.00    4.00  100.0%
 test-suite...ProxyApps-C++/CLAMR/CLAMR.test   172.00  229.00  33.1%
 test-suite...ks/Prolangs-C/agrep/agrep.test    10.00   12.00  20.0%
 test-suite...oxyApps-C++/miniFE/miniFE.test    44.00   51.00  15.9%
 test-suite...marks/7zip/7zip-benchmark.test   1285.00 1474.00 14.7%
 test-suite...006/450.soplex/450.soplex.test   254.00  289.00  13.8%
 test-suite...006/447.dealII/447.dealII.test   2466.00 2798.00 13.5%
 test-suite...000/197.parser/197.parser.test     9.00   10.00  11.1%
 test-suite.../Benchmarks/nbench/nbench.test    85.00   91.00   7.1%
 test-suite...ce/Applications/siod/siod.test    68.00   72.00   5.9%
 test-suite...ications/JM/lencod/lencod.test   786.00  824.00   4.8%
 test-suite...6/464.h264ref/464.h264ref.test   765.00  798.00   4.3%
 test-suite.../Benchmarks/Ptrdist/bc/bc.test   105.00  109.00   3.8%
 test-suite...lications/obsequi/Obsequi.test    29.00   28.00  -3.4%
 test-suite...3.xalancbmk/483.xalancbmk.test   1322.00 1367.00  3.4%
 test-suite...chmarks/MallocBench/gs/gs.test   118.00  122.00   3.4%
 test-suite...T2006/401.bzip2/401.bzip2.test    60.00   62.00   3.3%
 test-suite...6/482.sphinx3/482.sphinx3.test    30.00   31.00   3.3%
 test-suite...rks/tramp3d-v4/tramp3d-v4.test   862.00  887.00   2.9%
 test-suite...telecomm-gsm/telecomm-gsm.test    78.00   80.00   2.6%
 test-suite...ediabench/gsm/toast/toast.test    78.00   80.00   2.6%
 test-suite.../Applications/SPASS/SPASS.test   163.00  167.00   2.5%
 test-suite...lications/ClamAV/clamscan.test   240.00  245.00   2.1%
 test-suite...006/453.povray/453.povray.test   1392.00 1419.00  1.9%
 test-suite...000/255.vortex/255.vortex.test   211.00  215.00   1.9%
 test-suite...:: External/Povray/povray.test   1295.00 1317.00  1.7%
 test-suite...lications/sqlite3/sqlite3.test   175.00  177.00   1.1%
 test-suite...T2000/256.bzip2/256.bzip2.test    99.00  100.00   1.0%
 test-suite...0/253.perlbmk/253.perlbmk.test   629.00  635.00   1.0%
 test-suite.../CINT2006/403.gcc/403.gcc.test   1183.00 1194.00  0.9%
 test-suite.../CINT2000/176.gcc/176.gcc.test   647.00  653.00   0.9%
 test-suite...ications/JM/ldecod/ldecod.test   512.00  516.00   0.8%
 test-suite...0.perlbench/400.perlbench.test   1026.00 1034.00  0.8%
 test-suite...-typeset/consumer-typeset.test   1876.00 1877.00  0.1%
 Geomean difference                                             7.3%