[polly] Fix non-deterministic output due to iteration of unordered ScopArrayInfo

[mgrang]

Summary

This fixes the following failures in the reverse iteration builder:
http://lab.llvm.org:8011/builders/reverse-iteration/builds/25

Polly :: MaximalStaticExpansion/working_deps_between_inners.ll
Polly :: MaximalStaticExpansion/working_expansion_multiple_dependences_per_statement.ll
Polly :: MaximalStaticExpansion/working_expansion_multiple_instruction_per_statement.ll
Polly :: MaximalStaticExpansion/working_phi_expansion.ll

[grosser]

lib/Transform/MaximalStaticExpansion.cpp

504 ↗

(On Diff #113453)

Why do you need to sort the arrays. The original data structure is a SetVector and should consequently be deterministic. Should we just change the SmallPtrSet into a SmallVector? Would this be sufficient?

[mgrang]

lib/Transform/MaximalStaticExpansion.cpp

504 ↗

(On Diff #113453)

Yes, we actually do not need to sort as S.arrays() is a SetVector. Consequently, the unit tests do not need to be fixed either. Thanks!

polly/trunk/lib/Transform/MaximalStaticExpansion.cpp

bool MaximalStaticExpander::runOnScop(Scop &S) {
   // Get the ORE from OptimizationRemarkEmitterWrapperPass.
   ORE = &(getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE());
 
   // Get the RAW Dependences.
   auto &DI = getAnalysis<DependenceInfo>();
   auto &D = DI.getDependences(Dependences::AL_Reference);
   auto Dependences = isl::give(D.getDependences(Dependences::TYPE_RAW));
 
-  SmallPtrSet<ScopArrayInfo *, 4> CurrentSAI(S.arrays().begin(),
+  SmallVector<ScopArrayInfo *, 4> CurrentSAI(S.arrays().begin(),
                                              S.arrays().end());
 
   for (auto SAI : CurrentSAI) {
     SmallPtrSet<MemoryAccess *, 4> AllWrites;
     SmallPtrSet<MemoryAccess *, 4> AllReads;
     if (!isExpandable(SAI, AllWrites, AllReads, S, Dependences))
       continue;