cpu: Stop extracting inst_flags from the machInst.

The instruction representation is already encoded in the trace
protobuf, so there's no reason to encode a part of it again. This is
especially true since this supposedly generic code is extracting the
first 8 bits of the machInst, a totally arbitrary set of bits for most
ISAs. If certain bits within a machine instruction are actually
relevant, the consumer of the trace should be able to interpret the
instruction bytes which are already there and extract the same bits
within the context of whatever ISA they're appropriate for.

Change-Id: Idaebe6a110d7d4812c3d7c434582d5a9470bcec1
Reviewed-on: https://gem5-review.googlesource.com/9401
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/cpu/inst_pb_trace.cc

@@ -160,8 +160,6 @@ InstPBTrace::traceInst(ThreadContext *tc, StaticInstPtr si, TheISA::PCState pc)
     curMsg->set_cpuid(tc->cpuId());
     curMsg->set_tick(curTick());
     curMsg->set_type(static_cast<ProtoMessage::Inst_InstType>(si->opClass()));
-    curMsg->set_inst_flags(bits(si->machInst, 7, 0));
-
 }
 
 void

src/proto/inst.proto

@@ -101,6 +101,8 @@ message Inst {
   }
 
   optional InstType type = 6; // add, mul, fp add, load, store, simd add, …
+
+  // Deprecated:
   optional uint32 inst_flags = 7; // execution mode information
 
   // If the operation does one or more memory accesses