[polly] Change SmallPtrSet which are being iterated into SmallSetVector

[mgrang]

Summary

Otherwise the lack of an iteration order results in non-determinism in codegen.

[mgrang]

Tobias,

There is another SmallPtrSet in lib/Analysis/ScopInfo.h which is being iterated IslNodeBuilder.cpp:

SmallPtrSet<ScopArrayInfo *, 2> DerivedSAIs;
 const SmallPtrSetImpl<ScopArrayInfo *> &getDerivedSAIs() const {
   return DerivedSAIs;
}

I wanted to change this into a SmallSetVector but I am not sure how to replace SmallPtrSetImpl with a SmallSetVector version.

Any pointers would be appreciated.

Thanks,
Mandeep

[grosser]

LGTM.

[grosser]

Regarding the second change. I also don't see how we can use a SmallSetVectorImpl. I suggest to just use a SetVector for now. This is certainly correct and I doubt this part is performance critical. Feel free to commit such a change without further review.

lib/Analysis/ScopInfo.cpp

while (AGI != AG.end()) {
       }
     }
     if (NewAG.size() > 1)
       AliasGroups.push_back(std::move(NewAG));
     isl_set_free(AGDomain);
   }
 
   auto &F = getFunction();
-  MapVector<const Value *, SmallPtrSet<MemoryAccess *, 8>> ReadOnlyPairs;
+  MapVector<const Value *, SmallSetVector<MemoryAccess *, 8>> ReadOnlyPairs;
   SmallPtrSet<const Value *, 4> NonReadOnlyBaseValues;
   for (AliasGroupTy &AG : AliasGroups) {
     NonReadOnlyBaseValues.clear();
     ReadOnlyPairs.clear();
 
     if (AG.size() < 2) {
       AG.clear();
       continue;