[llvm] [LoopDist] Add some runtime checks for cross partition loads (PR #145623)

[Michael Kruse via llvm-commits]

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@@ -521,6 +521,38 @@ class InstPartitionContainer {
           Partition = -1;
       }
       assert(Partition != -2 && "Pointer not belonging to any partition");
+      // All the store context uses of our address were processed,
+      // Now make sure we don't have cross partition loads.
+      if (RtPtrCheck->Pointers[I].IsWritePtr) {
+        if (Ptr->hasOneUse() || Partition == -1)
+          continue;
+
+        bool ProcessLoads = false;
+        for (auto *U : Ptr->users()) {
+          auto *CurLoad = dyn_cast<LoadInst>(U);
+          if (!CurLoad)
+            continue;
+          if (!L->contains(CurLoad->getParent()))
+            continue;
+
+          ProcessLoads = true;
+          break;
+        }
+
+        if (!ProcessLoads)
+          continue;
+
+        const bool IsWritePtr = false;
+        auto ReadInstructions = LAI.getInstructionsForAccess(Ptr, IsWritePtr);
+        for (Instruction *ReadInst : ReadInstructions) {
+          if (Partition == (int)this->InstToPartitionId[ReadInst])
+            continue;
+
+          // -1 means belonging to multiple partitions.
+          Partition = -1;
+          break;
----------------
Meinersbur wrote:

This should be the same code as for the write case. Consider adding `LAI.getInstructionsForAccess(Ptr, false)` an d `LAI.getInstructionsForAccess(Ptr, true)` into a common list and iterator over it, or wrap this code into a lambda and calling it for each.

The former would be nicer if you changed the signature of `SmallVector<Instruction *, 4>MemoryDepChecker::getInstructionsForAccess(Value *Ptr, bool IsWrite)` to `void getInstructionsForAccess(Value *Ptr, bool IsWrite, SmallVectorImpl<Instruction*> &Result)` so one would reuse the same list. SmallVector's should not be returned anyway.

https://github.com/llvm/llvm-project/pull/145623