There are three methods involved in G1 C1 pre-barrier and they are connected by the call-chain:

```
   G1BarrierSetC1::pre_barrier
-> G1BarrierSetAssembler::gen_pre_barrier_stub
-> G1BarrierSetAssembler::generate_c1_pre_barrier_runtime_stub
```

In `G1BarrierSetAssembler::generate_c1_pre_barrier_runtime_stub`, it contains a is-marking-active check. Its caller, essentially `G1BarrierSetAssembler::gen_pre_barrier_stub` already knows marking is active, `// At this point we know that marking is in progress`, and actual check is in `G1BarrierSetC1::pre_barrier`.

Therefore, the following code (from x86, other arch have the same pattern) is redundant.

```
  // Is marking still active?
  if (in_bytes(SATBMarkQueue::byte_width_of_active()) == 4) {
    __ cmpl(queue_active, 0);
  } else {
    assert(in_bytes(SATBMarkQueue::byte_width_of_active()) == 1, "Assumption");
    __ cmpb(queue_active, 0);
  }
  __ jcc(Assembler::equal, done);
```