[llvm] [DirectX] Legalize memcpy (PR #139173)

[Farzon Lotfi via llvm-commits]

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@@ -246,6 +246,61 @@ downcastI64toI32InsertExtractElements(Instruction &I,
   }
 }
 
+static void emitMemcpyExpansion(IRBuilder<> &Builder, Value *Dst, Value *Src,
+                                ConstantInt *Length) {
+
+  uint64_t ByteLength = Length->getZExtValue();
+  if (ByteLength == 0)
+    return;
+
+  LLVMContext &Ctx = Builder.getContext();
+  const DataLayout &DL = Builder.GetInsertBlock()->getModule()->getDataLayout();
+
+  auto GetArrTyFromVal = [](Value *Val) -> ArrayType * {
+    assert(isa<AllocaInst>(Val) ||
+           isa<GlobalVariable>(Val) &&
+               "Expected Val to be an Alloca or Global Variable");
+    if (auto *Alloca = dyn_cast<AllocaInst>(Val))
+      return dyn_cast<ArrayType>(Alloca->getAllocatedType());
+    if (auto *GlobalVar = dyn_cast<GlobalVariable>(Val))
+      return dyn_cast<ArrayType>(GlobalVar->getValueType());
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farzonl wrote:

If legalization moves before  data scalarization do we need to handle memcpys for vectors?

https://github.com/llvm/llvm-project/pull/139173