cpu: Use the generic nop static inst instead of decoding the arch version.

This removes a dependence on the ISA.

Change-Id: I01013bc70558f0831327213912bcac11258066a6
Reviewed-on: https://gem5-review.googlesource.com/6824
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

src/cpu/o3/fetch_impl.hh

@@ -727,9 +727,8 @@ DefaultFetch<Impl>::finishTranslation(const Fault &fault, RequestPtr mem_req)
 
         DPRINTF(Fetch, "[tid:%i]: Translation faulted, building noop.\n", tid);
         // We will use a nop in ordier to carry the fault.
-        DynInstPtr instruction = buildInst(tid,
-                decoder[tid]->decode(TheISA::NoopMachInst, fetchPC.instAddr()),
-                NULL, fetchPC, fetchPC, false);
+        DynInstPtr instruction = buildInst(tid, StaticInst::nopStaticInstPtr,
+                                           NULL, fetchPC, fetchPC, false);
 
         instruction->setPredTarg(fetchPC);
         instruction->fault = fault;