arch: Add uReset helper to UPCState

This allows to reset without advancing the pc

https://gem5.atlassian.net/browse/GEM5-587

Change-Id: Ied566f4cd5efed5eb500447d3f14388482435475
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/30315
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Alexandru Duțu <alexandru.dutu@amd.com>

src/arch/generic/types.hh

@@ -1,4 +1,16 @@
 /*
+ * Copyright (c) 2020 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
  * Copyright (c) 2010 Gabe Black
  * All rights reserved.
  *
@@ -247,6 +259,14 @@ class UPCState : public SimplePCState<MachInst>
         _nupc = 1;
     }
 
+    // Reset the macroop's upc without advancing the regular pc.
+    void
+    uReset()
+    {
+        _upc = 0;
+        _nupc = 1;
+    }
+
     bool
     operator == (const UPCState<MachInst> &opc) const
     {