1 files changed, 38 insertions, 5 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 3a137a91367..c559d93e3f7 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -574,13 +574,46 @@ static Instruction *unpackLoadToAggregate(InstCombiner &IC, LoadInst &LI) {
   }
 
   if (auto *AT = dyn_cast<ArrayType>(T)) {
-    // If the array only have one element, we unpack.
-    if (AT->getNumElements() == 1) {
-      LoadInst *NewLoad = combineLoadToNewType(IC, LI, AT->getElementType(),
-                                               ".unpack");
+    auto *ET = AT->getElementType();
+    auto NumElements = AT->getNumElements();
+    if (NumElements == 1) {
+      LoadInst *NewLoad = combineLoadToNewType(IC, LI, ET, ".unpack");
       return IC.replaceInstUsesWith(LI, IC.Builder->CreateInsertValue(
-        UndefValue::get(T), NewLoad, 0, LI.getName()));
+        UndefValue::get(T), NewLoad, 0, Name));
     }
+
+    const DataLayout &DL = IC.getDataLayout();
+    auto EltSize = DL.getTypeAllocSize(ET);
+    auto Align = LI.getAlignment();
+    if (!Align)
+      Align = DL.getABITypeAlignment(T);
+
+    SmallString<16> LoadName = Name;
+    LoadName += ".unpack";
+    SmallString<16> EltName = Name;
+    EltName += ".elt";
+
+    auto *Addr = LI.getPointerOperand();
+    auto *IdxType = Type::getInt64Ty(T->getContext());
+    auto *Zero = ConstantInt::get(IdxType, 0);
+
+    Value *V = UndefValue::get(T);
+    uint64_t Offset = 0;
+    for (uint64_t i = 0; i < NumElements; i++) {
+      Value *Indices[2] = {
+        Zero,
+        ConstantInt::get(IdxType, i),
+      };
+      auto *Ptr = IC.Builder->CreateInBoundsGEP(AT, Addr, makeArrayRef(Indices),
+                                                EltName);
+      auto *L = IC.Builder->CreateAlignedLoad(Ptr, MinAlign(Align, Offset),
+                                              LoadName);
+      V = IC.Builder->CreateInsertValue(V, L, i);
+      Offset += EltSize;
+    }
+
+    V->setName(Name);
+    return IC.replaceInstUsesWith(LI, V);
   }
 
   return nullptr;