[llvm] [LSV] Enhance LoadStoreVectorizer to Handle Disjoint Flag in OR Instructions and Restore Vectorization Opportunities (PR #96495)

[Hao Li via llvm-commits]

================
@@ -437,9 +437,18 @@ bool Vectorizer::run() {
 
     SmallVector<BasicBlock::iterator, 8> Barriers;
     Barriers.push_back(BB->begin());
-    for (Instruction &I : *BB)
+    for (Instruction &I : *BB){
+      if (auto *OrInst = dyn_cast<PossiblyDisjointInst>(&I)) {
+        Value *Op0 = OrInst->getOperand(0);
+        Value *Op1 = OrInst->getOperand(1);
+
+        if (haveNoCommonBitsSet(Op0, Op1, DL)) {
+          OrInst->setIsDisjoint(true);
----------------
LiHao217 wrote:

 The backend I tested was not X86 but NVPTX. Without this change, llvm would not be able to autovectorize the following test case

```
Test case:
LLVM/test/Transforms/LoadStoreVectorizer/NVPTX/disjoint_or_vectorizer ll
Test the command:
opt -mtriple=nvptx64-nvidia-cuda -debug-pass-manager -passes=load-store-vectorizer -S -o -  llvm/test/Transforms/LoadStoreVectorizer/NVPTX/disjoint_or_vectorizer.ll
```

https://github.com/llvm/llvm-project/pull/96495