[llvm] [Attributor] Change allocation size and load/store offsets using AAPointerInfo for Alloca instructions and keep track of instructions causing an Access (PR #72029)

[Shilei Tian via llvm-commits]

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@@ -923,10 +930,95 @@ struct AA::PointerInfo::State : public AbstractState {
   BooleanState BS;
 };
 
+AAPointerInfo::AccessPathSetTy *AA::PointerInfo::State::findAllAccessPaths(
+    AAPointerInfo::OffsetInfoMapTy &OffsetInfoMap, Instruction *LocalI) {
+  AAPointerInfo::AccessPathSetTy *AccessPathsSet =
+      new AAPointerInfo::AccessPathSetTy();
+
+  // Store the instruction and its storage (i.e, which path it belongs to)
+  // on the stack.
+  // We also store the visited map on the stack.
+  // Since we want to find new paths, we want to make sure an instruction is
+  // not visited twice on the same path. However, we can visit the same
+  // instruction more that once if it exists on different paths.
+  using VisitedTy = SmallPtrSet<Value *, 4>;
+  using StackElementTy =
+      std::tuple<Value *, AAPointerInfo::AccessPathTy *, VisitedTy>;
+
+  SmallVector<StackElementTy, 16> Stack;
+
+  // Populate the stack with elements.
+  for (auto *It = LocalI->op_begin(); It != LocalI->op_end(); It++) {
+    Value *V = cast<Value>(It);
+    if (!OffsetInfoMap.contains(V))
+      continue;
+
+    SmallPtrSet<Value *, 4> LocalVisitedMap;
+    AAPointerInfo::AccessPathTy *NewPath = new AAPointerInfo::AccessPathTy();
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shiltian wrote:

here as well

https://github.com/llvm/llvm-project/pull/72029