I was in the process of learning FileCheck tool for llvm and I am following their official example.

I am using their llvm example code, i.e. test.ll:

define void @sub1(i32* %p, i32 %v) {
entry:
; CHECK: sub1:
; CHECK: subl
        %0 = tail call i32 @llvm.atomic.load.sub.i32.p0i32(i32* %p, i32 %v)
        ret void
}

define void @inc4(i64* %p) {
entry:
; CHECK: inc4:
; CHECK: incq
        %0 = tail call i64 @llvm.atomic.load.add.i64.p0i64(i64* %p, i64 1)
        ret void
}

and running llvm-as like this:

./build/bin/llvm-as < test.ll

and I am getting this error:

./build/bin/llvm-as: <stdin>:14:28: error: use of undefined value '@llvm.atomic.load.add.i64.p0i64'
        %0 = tail call i64 @llvm.atomic.load.add.i64.p0i64(i64* %p, i64 1)

How do I run this?