[LLVM] Don't peek through bitcast on pointers and gep with zero indices. NFC. (#102889)

Since we are using opaque pointers now, we don't need to peek through
bitcast on pointers and gep with zero indices.

1 files changed, 12 insertions, 41 deletions

diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index 9f7baa9..79504ca 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -291,10 +291,6 @@ MemoryDependenceResults::getInvariantGroupPointerDependency(LoadInst *LI,
   if (isa<GlobalValue>(LoadOperand))
     return MemDepResult::getUnknown();
 
-  // Queue to process all pointers that are equivalent to load operand.
-  SmallVector<const Value *, 8> LoadOperandsQueue;
-  LoadOperandsQueue.push_back(LoadOperand);
-
   Instruction *ClosestDependency = nullptr;
   // Order of instructions in uses list is unpredictible. In order to always
   // get the same result, we will look for the closest dominance.
@@ -305,44 +301,19 @@ MemoryDependenceResults::getInvariantGroupPointerDependency(LoadInst *LI,
     return Best;
   };
 
-  // FIXME: This loop is O(N^2) because dominates can be O(n) and in worst case
-  // we will see all the instructions. This should be fixed in MSSA.
-  while (!LoadOperandsQueue.empty()) {
-    const Value *Ptr = LoadOperandsQueue.pop_back_val();
-    assert(Ptr && !isa<GlobalValue>(Ptr) &&
-           "Null or GlobalValue should not be inserted");
-
-    for (const Use &Us : Ptr->uses()) {
-      auto *U = dyn_cast<Instruction>(Us.getUser());
-      if (!U || U == LI || !DT.dominates(U, LI))
-        continue;
-
-      // Bitcast or gep with zeros are using Ptr. Add to queue to check it's
-      // users.      U = bitcast Ptr
-      if (isa<BitCastInst>(U)) {
-        LoadOperandsQueue.push_back(U);
-        continue;
-      }
-      // Gep with zeros is equivalent to bitcast.
-      // FIXME: we are not sure if some bitcast should be canonicalized to gep 0
-      // or gep 0 to bitcast because of SROA, so there are 2 forms. When
-      // typeless pointers will be ready then both cases will be gone
-      // (and this BFS also won't be needed).
-      if (auto *GEP = dyn_cast<GetElementPtrInst>(U))
-        if (GEP->hasAllZeroIndices()) {
-          LoadOperandsQueue.push_back(U);
-          continue;
-        }
+  for (const Use &Us : LoadOperand->uses()) {
+    auto *U = dyn_cast<Instruction>(Us.getUser());
+    if (!U || U == LI || !DT.dominates(U, LI))
+      continue;
 
-      // If we hit load/store with the same invariant.group metadata (and the
-      // same pointer operand) we can assume that value pointed by pointer
-      // operand didn't change.
-      if ((isa<LoadInst>(U) ||
-           (isa<StoreInst>(U) &&
-            cast<StoreInst>(U)->getPointerOperand() == Ptr)) &&
-          U->hasMetadata(LLVMContext::MD_invariant_group))
-        ClosestDependency = GetClosestDependency(ClosestDependency, U);
-    }
+    // If we hit load/store with the same invariant.group metadata (and the
+    // same pointer operand) we can assume that value pointed by pointer
+    // operand didn't change.
+    if ((isa<LoadInst>(U) ||
+         (isa<StoreInst>(U) &&
+          cast<StoreInst>(U)->getPointerOperand() == LoadOperand)) &&
+        U->hasMetadata(LLVMContext::MD_invariant_group))
+      ClosestDependency = GetClosestDependency(ClosestDependency, U);
   }
 
   if (!ClosestDependency)