[PATCH] D13338: [Polly] Consolidate invariant loads

[Johannes Doerfert via llvm-commits]

jdoerfert created this revision.
jdoerfert added reviewers: grosser, Meinersbur.
jdoerfert added a subscriber: Polly.
Herald added a subscriber: sanjoy.

  If a (assumed) invariant location is loaded multiple times we
  generated a parameter for each location. However, this caused compile
  time problems for several benchmarks (e.g., 445_gobmk in SPEC2006 and
  BT in the NAS benchmarks). Additionally, the code we generate is
  suboptimal as we preload the same location multiple times and perform
  the same checks on all the parameters that refere to the same value.

  With this patch we consolidate the invariant loads in three steps:
    1) During the SCoP detection (assumed) invariant loads are kept in
       equivalence classes based on their pointer operand. One
       representing load is used to generate a parameter for the whole
       class, thus we never generate multiple parameters for the same
       location.
    2) During the SCoP generation we consolidate invariant memory
       accesses that are in the same equivalence class. While doing so
       we build the union of all execution domains as it is only
       important that the location is at least accessed once. However,
       we do not drop any invariant access we need to remap the access
       instruction later.
    3) During the code generation we preload one invariant access for
       each equivalence class and map all access instruction in that
       equivalence class to the preloaded value.

http://reviews.llvm.org/D13338

Files:
  include/polly/CodeGen/IslNodeBuilder.h
  include/polly/ScopDetection.h
  include/polly/ScopInfo.h
  include/polly/Support/SCEVAffinator.h
  include/polly/Support/SCEVValidator.h
  include/polly/Support/ScopHelper.h
  lib/Analysis/ScopDetection.cpp
  lib/Analysis/ScopInfo.cpp
  lib/CodeGen/BlockGenerators.cpp
  lib/CodeGen/CodeGeneration.cpp
  lib/CodeGen/IslNodeBuilder.cpp
  lib/Support/SCEVAffinator.cpp
  lib/Support/SCEVValidator.cpp
  lib/Support/ScopHelper.cpp
  test/Isl/CodeGen/invariant_load_base_pointer.ll
  test/Isl/CodeGen/invariant_load_base_pointer_conditional.ll
  test/Isl/CodeGen/invariant_load_condition.ll
  test/Isl/CodeGen/invariant_load_escaping_second_scop.ll
  test/Isl/CodeGen/invariant_load_loop_ub.ll
  test/Isl/CodeGen/invariant_load_outermost.ll
  test/Isl/CodeGen/invariant_load_parameters_cyclic_dependence.ll
  test/Isl/CodeGen/invariant_load_ptr_ptr_noalias.ll
  test/Isl/CodeGen/invariant_load_scalar_dep.ll
  test/Isl/CodeGen/reduction_2.ll
  test/Isl/CodeGen/whole-scop-non-affine-subregion.ll
  test/ScopDetect/base_pointer.ll
  test/ScopDetectionDiagnostics/ReportLoopBound-01.ll
  test/ScopDetectionDiagnostics/ReportVariantBasePtr-01.ll
  test/ScopInfo/NonAffine/non-affine-loop-condition-dependent-access_1.ll
  test/ScopInfo/NonAffine/non_affine_conditional_surrounding_affine_loop.ll
  test/ScopInfo/NonAffine/non_affine_conditional_surrounding_non_affine_loop.ll
  test/ScopInfo/intra_and_inter_bb_scalar_dep.ll
  test/ScopInfo/invariant_load_base_pointer.ll
  test/ScopInfo/invariant_load_base_pointer_conditional.ll
  test/ScopInfo/invariant_load_condition.ll
  test/ScopInfo/invariant_load_loop_ub.ll
  test/ScopInfo/invariant_load_ptr_ptr_noalias.ll
  test/ScopInfo/invariant_load_scalar_dep.ll
  test/ScopInfo/invariant_loads_complicated_dependences.ll
  test/ScopInfo/invariant_loads_cyclic_dependences.ll
  test/ScopInfo/invariant_loop_bounds.ll
  test/ScopInfo/invariant_same_loop_bound_multiple_times-1.ll
  test/ScopInfo/invariant_same_loop_bound_multiple_times-2.ll
  test/ScopInfo/required-invariant-loop-bounds.ll

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