[LLVM][TableGen] Check validity of IIT encoding for vector types (#111152)

Add assert to verify that the `IIT_Vecs` list for IIT encoding of vector
types is not empty for vector types (else it will generate an invalid
IIT encoding).

Remove `llvm_v2048i1_ty` for which this assert fails, since the
`Intrinsics.td` file does not define any IIT encoding for vectors of
size 2048.

Author: jurahul

llvm/include/llvm/IR/Intrinsics.td

@@ -372,6 +372,10 @@ class LLVMType<ValueType vt> {
     []);
   assert !le(!size(IIT_Vecs), 1), "Duplicate type";
 
+  // For vector types, assert that the IIT_Vecs list is not empty.
+  assert !or(!not(vt.isVector), !not(!empty(IIT_Vecs))),
+         "Invalid IIT encoding for vector type v" # vt.nElem # vt.ElementType;
+
   list<int> Sig = !listconcat(
     !if(vt.isScalable, [IIT_SCALABLE_VEC.Number], []),
     !foreach(iit, IIT_Vecs, iit.Number),
@@ -518,7 +522,6 @@ def llvm_v128i1_ty     : LLVMType<v128i1>;   // 128 x i1
 def llvm_v256i1_ty     : LLVMType<v256i1>;   // 256 x i1
 def llvm_v512i1_ty     : LLVMType<v512i1>;   // 512 x i1
 def llvm_v1024i1_ty    : LLVMType<v1024i1>;  //1024 x i1
-def llvm_v2048i1_ty    : LLVMType<v2048i1>;  //2048 x i1
 
 def llvm_v1i8_ty       : LLVMType<v1i8>;     //  1 x i8
 def llvm_v2i8_ty       : LLVMType<v2i8>;     //  2 x i8