[m5-dev] changeset in m5: X86: Only reset npc to reflect instruction leng...

[Gabe Black]

changeset be8762db2561 in /z/repo/m5
details: http://repo.m5sim.org/m5?cmd=changeset;node=be8762db2561
description:
        X86: Only reset npc to reflect instruction length once.

        When redirecting fetch to handle branches, the npc of the current pc 
state
        needs to be left alone. This change makes the pc state record whether 
or not
        the npc already reflects a real value by making it keep track of the 
current
        instruction size, or if no size has been set.

diffstat:

 src/arch/x86/predecoder.hh |   6 ++++-
 src/arch/x86/types.hh      |  50 +++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 54 insertions(+), 2 deletions(-)

diffs (76 lines):

diff -r 6d955240bb62 -r be8762db2561 src/arch/x86/predecoder.hh
--- a/src/arch/x86/predecoder.hh        Sun Feb 13 17:40:07 2011 -0800
+++ b/src/arch/x86/predecoder.hh        Sun Feb 13 17:41:10 2011 -0800
@@ -225,7 +225,11 @@
         {
             assert(emiIsReady);
             emiIsReady = false;
-            nextPC.npc(nextPC.pc() + getInstSize());
+            if (!nextPC.size()) {
+                Addr size = getInstSize();
+                nextPC.size(size);
+                nextPC.npc(nextPC.pc() + size);
+            }
             return emi;
         }
     };
diff -r 6d955240bb62 -r be8762db2561 src/arch/x86/types.hh
--- a/src/arch/x86/types.hh     Sun Feb 13 17:40:07 2011 -0800
+++ b/src/arch/x86/types.hh     Sun Feb 13 17:41:10 2011 -0800
@@ -222,7 +222,55 @@
         return true;
     }
 
-    typedef GenericISA::UPCState<MachInst> PCState;
+    class PCState : public GenericISA::UPCState<MachInst>
+    {
+      protected:
+        typedef GenericISA::UPCState<MachInst> Base;
+
+        uint8_t _size;
+
+      public:
+        void
+        set(Addr val)
+        {
+            Base::set(val);
+            _size = 0;
+        }
+
+        PCState() {}
+        PCState(Addr val) { set(val); }
+
+        uint8_t size() const { return _size; }
+        void size(uint8_t newSize) { _size = newSize; }
+
+        void
+        advance()
+        {
+            Base::advance();
+            _size = 0;
+        }
+
+        void
+        uEnd()
+        {
+            Base::uEnd();
+            _size = 0;
+        }
+
+        void
+        serialize(std::ostream &os)
+        {
+            Base::serialize(os);
+            SERIALIZE_SCALAR(_size);
+        }
+
+        void
+        unserialize(Checkpoint *cp, const std::string &section)
+        {
+            Base::unserialize(cp, section);
+            UNSERIALIZE_SCALAR(_size);
+        }
+    };
 
     struct CoreSpecific {
         int core_type;
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