arch: Use const StaticInstPtr references where possible

This patch optimises the passing of StaticInstPtr by avoiding copying
the reference-counting pointer. This avoids first incrementing and
then decrementing the reference-counting pointer.

47 files changed, 194 insertions, 191 deletions

diff --git a/src/arch/alpha/faults.cc b/src/arch/alpha/faults.cc
index e4a5c9223..6375b0bfb 100644
--- a/src/arch/alpha/faults.cc
+++ b/src/arch/alpha/faults.cc
@@ -106,7 +106,7 @@ FaultVect IntegerOverflowFault::_vect = 0x0501;
 FaultStat IntegerOverflowFault::_count;
 
 void
-AlphaFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+AlphaFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     FaultBase::invoke(tc);
     if (!FullSystem)
@@ -130,7 +130,7 @@ AlphaFault::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-ArithmeticFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+ArithmeticFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     FaultBase::invoke(tc);
     if (!FullSystem)
@@ -139,7 +139,7 @@ ArithmeticFault::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-DtbFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+DtbFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         // Set fault address and flags.  Even though we're modeling an
@@ -169,7 +169,7 @@ DtbFault::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-ItbFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+ItbFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         if (!tc->misspeculating()) {
@@ -183,7 +183,7 @@ ItbFault::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-ItbPageFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+ItbPageFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         ItbFault::invoke(tc);
@@ -202,7 +202,7 @@ ItbPageFault::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-NDtbMissFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+NDtbMissFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         DtbFault::invoke(tc, inst);
diff --git a/src/arch/alpha/faults.hh b/src/arch/alpha/faults.hh
index 7eddd14eb..4a5e036fd 100644
--- a/src/arch/alpha/faults.hh
+++ b/src/arch/alpha/faults.hh
@@ -48,8 +48,8 @@ class AlphaFault : public FaultBase
     virtual bool skipFaultingInstruction() {return false;}
     virtual bool setRestartAddress() {return true;}
   public:
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
     virtual FaultVect vect() = 0;
     virtual FaultStat & countStat() = 0;
 };
@@ -108,8 +108,8 @@ class ArithmeticFault : public AlphaFault
     FaultName name() const {return _name;}
     FaultVect vect() {return _vect;}
     FaultStat & countStat() {return _count;}
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class InterruptFault : public AlphaFault
@@ -142,8 +142,8 @@ class DtbFault : public AlphaFault
     FaultName name() const = 0;
     FaultVect vect() = 0;
     FaultStat & countStat() = 0;
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class NDtbMissFault : public DtbFault
@@ -160,8 +160,8 @@ class NDtbMissFault : public DtbFault
     FaultName name() const {return _name;}
     FaultVect vect() {return _vect;}
     FaultStat & countStat() {return _count;}
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class PDtbMissFault : public DtbFault
@@ -238,8 +238,8 @@ class ItbFault : public AlphaFault
     FaultName name() const = 0;
     FaultVect vect() = 0;
     FaultStat & countStat() = 0;
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class ItbPageFault : public ItbFault
@@ -254,8 +254,8 @@ class ItbPageFault : public ItbFault
     FaultName name() const {return _name;}
     FaultVect vect() {return _vect;}
     FaultStat & countStat() {return _count;}
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class ItbAcvFault : public ItbFault
diff --git a/src/arch/alpha/stacktrace.cc b/src/arch/alpha/stacktrace.cc
index 8c0e85af4..f48955715 100644
--- a/src/arch/alpha/stacktrace.cc
+++ b/src/arch/alpha/stacktrace.cc
@@ -122,7 +122,7 @@ StackTrace::StackTrace()
 {
 }
 
-StackTrace::StackTrace(ThreadContext *_tc, StaticInstPtr inst)
+StackTrace::StackTrace(ThreadContext *_tc, const StaticInstPtr &inst)
     : tc(0), stack(64)
 {
     trace(_tc, inst);
diff --git a/src/arch/alpha/stacktrace.hh b/src/arch/alpha/stacktrace.hh
index 669c65781..59174c568 100644
--- a/src/arch/alpha/stacktrace.hh
+++ b/src/arch/alpha/stacktrace.hh
@@ -76,7 +76,7 @@ class StackTrace
 
   public:
     StackTrace();
-    StackTrace(ThreadContext *tc, StaticInstPtr inst);
+    StackTrace(ThreadContext *tc, const StaticInstPtr &inst);
     ~StackTrace();
 
     void
@@ -87,7 +87,7 @@ class StackTrace
     }
 
     bool valid() const { return tc != NULL; }
-    bool trace(ThreadContext *tc, StaticInstPtr inst);
+    bool trace(ThreadContext *tc, const StaticInstPtr &inst);
 
   public:
     const std::vector<Addr> &getstack() const { return stack; }
@@ -111,7 +111,7 @@ class StackTrace
 };
 
 inline bool
-StackTrace::trace(ThreadContext *tc, StaticInstPtr inst)
+StackTrace::trace(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (!inst->isCall() && !inst->isReturn())
         return false;
diff --git a/src/arch/alpha/utility.hh b/src/arch/alpha/utility.hh
index 72643cb16..a52125066 100644
--- a/src/arch/alpha/utility.hh
+++ b/src/arch/alpha/utility.hh
@@ -105,7 +105,7 @@ void copyMiscRegs(ThreadContext *src, ThreadContext *dest);
 void skipFunction(ThreadContext *tc);
 
 inline void
-advancePC(PCState &pc, const StaticInstPtr inst)
+advancePC(PCState &pc, const StaticInstPtr &inst)
 {
     pc.advance();
 }
diff --git a/src/arch/arm/faults.cc b/src/arch/arm/faults.cc
index 94a82b9d5..9d373e469 100644
--- a/src/arch/arm/faults.cc
+++ b/src/arch/arm/faults.cc
@@ -426,7 +426,7 @@ ArmFault::setSyndrome(ThreadContext *tc, MiscRegIndex syndrome_reg)
 }
 
 void
-ArmFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+ArmFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     CPSR cpsr = tc->readMiscReg(MISCREG_CPSR);
 
@@ -587,7 +587,7 @@ ArmFault::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-ArmFault::invoke64(ThreadContext *tc, StaticInstPtr inst)
+ArmFault::invoke64(ThreadContext *tc, const StaticInstPtr &inst)
 {
     // Determine actual misc. register indices for ELR_ELx and SPSR_ELx
     MiscRegIndex elr_idx, spsr_idx;
@@ -678,7 +678,7 @@ ArmFault::invoke64(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-Reset::invoke(ThreadContext *tc, StaticInstPtr inst)
+Reset::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         tc->getCpuPtr()->clearInterrupts();
@@ -706,7 +706,7 @@ Reset::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-UndefinedInstruction::invoke(ThreadContext *tc, StaticInstPtr inst)
+UndefinedInstruction::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         ArmFault::invoke(tc, inst);
@@ -767,7 +767,7 @@ UndefinedInstruction::iss() const
 }
 
 void
-SupervisorCall::invoke(ThreadContext *tc, StaticInstPtr inst)
+SupervisorCall::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         ArmFault::invoke(tc, inst);
@@ -884,7 +884,7 @@ ArmFaultVals<T>::offset(ThreadContext *tc)
 // }
 
 void
-SecureMonitorCall::invoke(ThreadContext *tc, StaticInstPtr inst)
+SecureMonitorCall::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         ArmFault::invoke(tc, inst);
@@ -913,7 +913,7 @@ SecureMonitorTrap::ec(ThreadContext *tc) const
 
 template<class T>
 void
-AbortFault<T>::invoke(ThreadContext *tc, StaticInstPtr inst)
+AbortFault<T>::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (tranMethod == ArmFault::UnknownTran) {
         tranMethod = longDescFormatInUse(tc) ? ArmFault::LpaeTran
@@ -1237,7 +1237,7 @@ DataAbort::annotate(AnnotationIDs id, uint64_t val)
 }
 
 void
-VirtualDataAbort::invoke(ThreadContext *tc, StaticInstPtr inst)
+VirtualDataAbort::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     AbortFault<VirtualDataAbort>::invoke(tc, inst);
     HCR hcr = tc->readMiscRegNoEffect(MISCREG_HCR);
@@ -1336,7 +1336,7 @@ VirtualFastInterrupt::VirtualFastInterrupt()
 {}
 
 void
-PCAlignmentFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+PCAlignmentFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     ArmFaultVals<PCAlignmentFault>::invoke(tc, inst);
     assert(from64);
@@ -1351,7 +1351,7 @@ SystemError::SystemError()
 {}
 
 void
-SystemError::invoke(ThreadContext *tc, StaticInstPtr inst)
+SystemError::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     tc->getCpuPtr()->clearInterrupt(INT_ABT, 0);
     ArmFault::invoke(tc, inst);
@@ -1382,7 +1382,7 @@ SystemError::routeToHyp(ThreadContext *tc) const
 }
 
 void
-FlushPipe::invoke(ThreadContext *tc, StaticInstPtr inst) {
+FlushPipe::invoke(ThreadContext *tc, const StaticInstPtr &inst) {
     DPRINTF(Faults, "Invoking FlushPipe Fault\n");
 
     // Set the PC to the next instruction of the faulting instruction.
@@ -1395,7 +1395,7 @@ FlushPipe::invoke(ThreadContext *tc, StaticInstPtr inst) {
 }
 
 void
-ArmSev::invoke(ThreadContext *tc, StaticInstPtr inst) {
+ArmSev::invoke(ThreadContext *tc, const StaticInstPtr &inst) {
     DPRINTF(Faults, "Invoking ArmSev Fault\n");
     if (!FullSystem)
         return;
diff --git a/src/arch/arm/faults.hh b/src/arch/arm/faults.hh
index 8a6f07dde..4980c12e1 100644
--- a/src/arch/arm/faults.hh
+++ b/src/arch/arm/faults.hh
@@ -181,10 +181,10 @@ class ArmFault : public FaultBase
     // exception level
     MiscRegIndex getFaultAddrReg64() const;
 
-    void invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
-    void invoke64(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
+    void invoke64(ThreadContext *tc, const StaticInstPtr &inst =
+                  StaticInst::nullStaticInstPtr);
     virtual void annotate(AnnotationIDs id, uint64_t val) {}
     virtual FaultStat& countStat() = 0;
     virtual FaultOffset offset(ThreadContext *tc) = 0;
@@ -249,8 +249,8 @@ class ArmFaultVals : public ArmFault
 class Reset : public ArmFaultVals<Reset>
 {
   public:
-    void invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class UndefinedInstruction : public ArmFaultVals<UndefinedInstruction>
@@ -277,8 +277,8 @@ class UndefinedInstruction : public ArmFaultVals<UndefinedInstruction>
         mnemonic(_mnemonic)
     {}
 
-    void invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
     bool routeToHyp(ThreadContext *tc) const;
     ExceptionClass ec(ThreadContext *tc) const;
     uint32_t iss() const;
@@ -295,8 +295,8 @@ class SupervisorCall : public ArmFaultVals<SupervisorCall>
         overrideEc(_overrideEc)
     {}
 
-    void invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
     bool routeToHyp(ThreadContext *tc) const;
     ExceptionClass ec(ThreadContext *tc) const;
     uint32_t iss() const;
@@ -309,8 +309,8 @@ class SecureMonitorCall : public ArmFaultVals<SecureMonitorCall>
         ArmFaultVals<SecureMonitorCall>(_machInst)
     {}
 
-    void invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
     ExceptionClass ec(ThreadContext *tc) const;
     uint32_t iss() const;
 };
@@ -401,8 +401,8 @@ class AbortFault : public ArmFaultVals<T>
         stage2(_stage2), s1ptw(false), tranMethod(_tranMethod)
     {}
 
-    void invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 
     FSR getFsr(ThreadContext *tc);
     bool abortDisable(ThreadContext *tc);
@@ -473,7 +473,7 @@ class VirtualDataAbort : public AbortFault<VirtualDataAbort>
         AbortFault<VirtualDataAbort>(_addr, _write, _domain, _source, false)
     {}
 
-    void invoke(ThreadContext *tc, StaticInstPtr inst);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst);
 };
 
 class Interrupt : public ArmFaultVals<Interrupt>
@@ -514,8 +514,8 @@ class PCAlignmentFault : public ArmFaultVals<PCAlignmentFault>
   public:
     PCAlignmentFault(Addr _faultPC) : faultPC(_faultPC)
     {}
-    void invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 /// Stack pointer alignment fault (AArch64 only)
@@ -530,8 +530,8 @@ class SystemError : public ArmFaultVals<SystemError>
 {
   public:
     SystemError();
-    void invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
     bool routeToMonitor(ThreadContext *tc) const;
     bool routeToHyp(ThreadContext *tc) const;
 };
@@ -541,8 +541,8 @@ class FlushPipe : public ArmFaultVals<FlushPipe>
 {
   public:
     FlushPipe() {}
-    void invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 // A fault that flushes the pipe, excluding the faulting instructions
@@ -550,8 +550,8 @@ class ArmSev : public ArmFaultVals<ArmSev>
 {
   public:
     ArmSev () {}
-    void invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 /// Illegal Instruction Set State fault (AArch64 only)
diff --git a/src/arch/arm/stacktrace.cc b/src/arch/arm/stacktrace.cc
index 8575e1347..7cc650c58 100644
--- a/src/arch/arm/stacktrace.cc
+++ b/src/arch/arm/stacktrace.cc
@@ -121,7 +121,7 @@ namespace ArmISA
     {
     }
 
-    StackTrace::StackTrace(ThreadContext *_tc, StaticInstPtr inst)
+    StackTrace::StackTrace(ThreadContext *_tc, const StaticInstPtr &inst)
         : tc(0), stack(64)
     {
         trace(_tc, inst);
diff --git a/src/arch/arm/stacktrace.hh b/src/arch/arm/stacktrace.hh
index f88ed352b..b0a4a8adc 100644
--- a/src/arch/arm/stacktrace.hh
+++ b/src/arch/arm/stacktrace.hh
@@ -78,7 +78,7 @@ class StackTrace
 
   public:
     StackTrace();
-    StackTrace(ThreadContext *tc, StaticInstPtr inst);
+    StackTrace(ThreadContext *tc, const StaticInstPtr &inst);
     ~StackTrace();
 
     void clear()
@@ -88,7 +88,7 @@ class StackTrace
     }
 
     bool valid() const { return tc != NULL; }
-    bool trace(ThreadContext *tc, StaticInstPtr inst);
+    bool trace(ThreadContext *tc, const StaticInstPtr &inst);
 
   public:
     const std::vector<Addr> &getstack() const { return stack; }
@@ -106,7 +106,7 @@ class StackTrace
 };
 
 inline bool
-StackTrace::trace(ThreadContext *tc, StaticInstPtr inst)
+StackTrace::trace(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (!inst->isCall() && !inst->isReturn())
         return false;
diff --git a/src/arch/arm/utility.hh b/src/arch/arm/utility.hh
index 2318f1aa9..0c29ac90e 100644
--- a/src/arch/arm/utility.hh
+++ b/src/arch/arm/utility.hh
@@ -279,7 +279,7 @@ uint64_t getArgument(ThreadContext *tc, int &number, uint16_t size, bool fp);
 void skipFunction(ThreadContext *tc);
 
 inline void
-advancePC(PCState &pc, const StaticInstPtr inst)
+advancePC(PCState &pc, const StaticInstPtr &inst)
 {
     inst->advancePC(pc);
 }
diff --git a/src/arch/generic/debugfaults.hh b/src/arch/generic/debugfaults.hh
index fcfdfb9e1..aeb2261a7 100644
--- a/src/arch/generic/debugfaults.hh
+++ b/src/arch/generic/debugfaults.hh
@@ -86,8 +86,8 @@ class M5DebugFault : public FaultBase
     }
 
     void
-    invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr)
+    invoke(ThreadContext *tc, const StaticInstPtr &inst =
+           StaticInst::nullStaticInstPtr)
     {
         switch (func) {
           case PanicFunc:
diff --git a/src/arch/mips/faults.cc b/src/arch/mips/faults.cc
index 3697601dc..eae6bc927 100644
--- a/src/arch/mips/faults.cc
+++ b/src/arch/mips/faults.cc
@@ -131,7 +131,7 @@ MipsFaultBase::setExceptionState(ThreadContext *tc, uint8_t excCode)
 }
 
 void
-MipsFaultBase::invoke(ThreadContext *tc, StaticInstPtr inst)
+MipsFaultBase::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         DPRINTF(MipsPRA, "Fault %s encountered.\n", name());
@@ -143,7 +143,7 @@ MipsFaultBase::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-ResetFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+ResetFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         DPRINTF(MipsPRA, "%s encountered.\n", name());
@@ -160,13 +160,13 @@ ResetFault::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-SoftResetFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+SoftResetFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     panic("Soft reset not implemented.\n");
 }
 
 void
-NonMaskableInterrupt::invoke(ThreadContext *tc, StaticInstPtr inst)
+NonMaskableInterrupt::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     panic("Non maskable interrupt not implemented.\n");
 }
diff --git a/src/arch/mips/faults.hh b/src/arch/mips/faults.hh
index 98638ac9a..d843acc50 100644
--- a/src/arch/mips/faults.hh
+++ b/src/arch/mips/faults.hh
@@ -102,8 +102,8 @@ class MipsFaultBase : public FaultBase
         return base(tc) + offset(tc);
     }
 
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 template <typename T>
@@ -134,23 +134,23 @@ class MachineCheckFault : public MipsFault<MachineCheckFault>
 class ResetFault : public MipsFault<ResetFault>
 {
   public:
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 
 };
 
 class SoftResetFault : public MipsFault<SoftResetFault>
 {
   public:
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class NonMaskableInterrupt : public MipsFault<NonMaskableInterrupt>
 {
   public:
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class CoprocessorUnusableFault : public MipsFault<CoprocessorUnusableFault>
@@ -162,8 +162,8 @@ class CoprocessorUnusableFault : public MipsFault<CoprocessorUnusableFault>
     {}
 
     void
-    invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr)
+    invoke(ThreadContext * tc, const StaticInstPtr &inst =
+           StaticInst::nullStaticInstPtr)
     {
         MipsFault<CoprocessorUnusableFault>::invoke(tc, inst);
         if (FullSystem) {
@@ -197,8 +197,8 @@ class AddressFault : public MipsFault<T>
     {}
 
     void
-    invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr)
+    invoke(ThreadContext * tc, const StaticInstPtr &inst =
+           StaticInst::nullStaticInstPtr)
     {
         MipsFault<T>::invoke(tc, inst);
         if (FullSystem)
@@ -250,8 +250,8 @@ class TlbFault : public AddressFault<T>
     }
 
     void
-    invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr)
+    invoke(ThreadContext * tc, const StaticInstPtr &inst =
+           StaticInst::nullStaticInstPtr)
     {
         if (FullSystem) {
             DPRINTF(MipsPRA, "Fault %s encountered.\n", this->name());
diff --git a/src/arch/mips/stacktrace.cc b/src/arch/mips/stacktrace.cc
index bb761a243..78457c09c 100644
--- a/src/arch/mips/stacktrace.cc
+++ b/src/arch/mips/stacktrace.cc
@@ -96,7 +96,7 @@ StackTrace::StackTrace()
 {
 }
 
-StackTrace::StackTrace(ThreadContext *_tc, StaticInstPtr inst)
+StackTrace::StackTrace(ThreadContext *_tc, const StaticInstPtr &inst)
     : tc(0), stack(64)
 {
     trace(_tc, inst);
diff --git a/src/arch/mips/stacktrace.hh b/src/arch/mips/stacktrace.hh
index f4dc04d29..c817824ea 100644
--- a/src/arch/mips/stacktrace.hh
+++ b/src/arch/mips/stacktrace.hh
@@ -75,7 +75,7 @@ class StackTrace
 
   public:
     StackTrace();
-    StackTrace(ThreadContext *tc, StaticInstPtr inst);
+    StackTrace(ThreadContext *tc, const StaticInstPtr &inst);
     ~StackTrace();
 
     void clear()
@@ -85,7 +85,7 @@ class StackTrace
     }
 
     bool valid() const { return tc != NULL; }
-    bool trace(ThreadContext *tc, StaticInstPtr inst);
+    bool trace(ThreadContext *tc, const StaticInstPtr &inst);
 
   public:
     const std::vector<Addr> &getstack() const { return stack; }
@@ -107,7 +107,7 @@ class StackTrace
 };
 
 inline bool
-StackTrace::trace(ThreadContext *tc, StaticInstPtr inst)
+StackTrace::trace(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (!inst->isCall() && !inst->isReturn())
         return false;
diff --git a/src/arch/mips/utility.hh b/src/arch/mips/utility.hh
index 876066203..242dddbf7 100644
--- a/src/arch/mips/utility.hh
+++ b/src/arch/mips/utility.hh
@@ -115,7 +115,7 @@ void copyMiscRegs(ThreadContext *src, ThreadContext *dest);
 void skipFunction(ThreadContext *tc);
 
 inline void
-advancePC(PCState &pc, const StaticInstPtr inst)
+advancePC(PCState &pc, const StaticInstPtr &inst)
 {
     pc.advance();
 }
diff --git a/src/arch/power/stacktrace.cc b/src/arch/power/stacktrace.cc
index 315cf0ae5..f241dfecb 100644
--- a/src/arch/power/stacktrace.cc
+++ b/src/arch/power/stacktrace.cc
@@ -69,7 +69,7 @@ StackTrace::StackTrace()
     panic("StackTrace constructor not implemented.\n");
 }
 
-StackTrace::StackTrace(ThreadContext *_tc, StaticInstPtr inst)
+StackTrace::StackTrace(ThreadContext *_tc, const StaticInstPtr &inst)
     : tc(0), stack(64)
 {
     panic("StackTrace constructor not implemented.\n");
diff --git a/src/arch/power/stacktrace.hh b/src/arch/power/stacktrace.hh
index 65badad24..aec91837c 100644
--- a/src/arch/power/stacktrace.hh
+++ b/src/arch/power/stacktrace.hh
@@ -73,7 +73,7 @@ class StackTrace
 
   public:
     StackTrace();
-    StackTrace(ThreadContext *tc, StaticInstPtr inst);
+    StackTrace(ThreadContext *tc, const StaticInstPtr &inst);
     ~StackTrace();
 
     void
@@ -89,7 +89,7 @@ class StackTrace
         return tc != NULL;
     }
 
-    bool trace(ThreadContext *tc, StaticInstPtr inst);
+    bool trace(ThreadContext *tc, const StaticInstPtr &inst);
 
   public:
     const std::vector<Addr> &
@@ -123,7 +123,7 @@ class StackTrace
 };
 
 inline bool
-StackTrace::trace(ThreadContext *tc, StaticInstPtr inst)
+StackTrace::trace(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (!inst->isCall() && !inst->isReturn())
         return false;
diff --git a/src/arch/power/utility.hh b/src/arch/power/utility.hh
index 907e451b9..1a13d1e40 100644
--- a/src/arch/power/utility.hh
+++ b/src/arch/power/utility.hh
@@ -73,7 +73,7 @@ copyMiscRegs(ThreadContext *src, ThreadContext *dest)
 void skipFunction(ThreadContext *tc);
 
 inline void
-advancePC(PCState &pc, const StaticInstPtr inst)
+advancePC(PCState &pc, const StaticInstPtr &inst)
 {
     pc.advance();
 }
diff --git a/src/arch/sparc/faults.cc b/src/arch/sparc/faults.cc
index a5c8a3a4e..8ace3cb25 100644
--- a/src/arch/sparc/faults.cc
+++ b/src/arch/sparc/faults.cc
@@ -490,7 +490,7 @@ getPrivVector(ThreadContext *tc, Addr &PC, Addr &NPC, MiscReg TT, MiscReg TL)
 }
 
 void
-SparcFaultBase::invoke(ThreadContext * tc, StaticInstPtr inst)
+SparcFaultBase::invoke(ThreadContext * tc, const StaticInstPtr &inst)
 {
     FaultBase::invoke(tc);
     if (!FullSystem)
@@ -551,7 +551,7 @@ SparcFaultBase::invoke(ThreadContext * tc, StaticInstPtr inst)
 }
 
 void
-PowerOnReset::invoke(ThreadContext *tc, StaticInstPtr inst)
+PowerOnReset::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     // For SPARC, when a system is first started, there is a power
     // on reset Trap which sets the processor into the following state.
@@ -614,7 +614,8 @@ PowerOnReset::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-FastInstructionAccessMMUMiss::invoke(ThreadContext *tc, StaticInstPtr inst)
+FastInstructionAccessMMUMiss::invoke(ThreadContext *tc,
+                                     const StaticInstPtr &inst)
 {
     if (FullSystem) {
         SparcFaultBase::invoke(tc, inst);
@@ -634,7 +635,7 @@ FastInstructionAccessMMUMiss::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-FastDataAccessMMUMiss::invoke(ThreadContext *tc, StaticInstPtr inst)
+FastDataAccessMMUMiss::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         SparcFaultBase::invoke(tc, inst);
@@ -658,7 +659,7 @@ FastDataAccessMMUMiss::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-SpillNNormal::invoke(ThreadContext *tc, StaticInstPtr inst)
+SpillNNormal::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         SparcFaultBase::invoke(tc, inst);
@@ -678,7 +679,7 @@ SpillNNormal::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-FillNNormal::invoke(ThreadContext *tc, StaticInstPtr inst)
+FillNNormal::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         SparcFaultBase::invoke(tc, inst);
@@ -698,7 +699,7 @@ FillNNormal::invoke(ThreadContext *tc, StaticInstPtr inst)
 }
 
 void
-TrapInstruction::invoke(ThreadContext *tc, StaticInstPtr inst)
+TrapInstruction::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         SparcFaultBase::invoke(tc, inst);
diff --git a/src/arch/sparc/faults.hh b/src/arch/sparc/faults.hh
index 1fee832d3..9d5f7e01d 100644
--- a/src/arch/sparc/faults.hh
+++ b/src/arch/sparc/faults.hh
@@ -65,8 +65,8 @@ class SparcFaultBase : public FaultBase
         const PrivilegeLevel nextPrivilegeLevel[NumLevels];
         FaultStat count;
     };
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
     virtual TrapType trapType() = 0;
     virtual FaultPriority priority() = 0;
     virtual FaultStat & countStat() = 0;
@@ -93,8 +93,8 @@ class SparcFault : public SparcFaultBase
 
 class PowerOnReset : public SparcFault<PowerOnReset>
 {
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class WatchDogReset : public SparcFault<WatchDogReset> {};
@@ -206,8 +206,8 @@ class FastInstructionAccessMMUMiss :
     {}
     FastInstructionAccessMMUMiss() : vaddr(0)
     {}
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class FastDataAccessMMUMiss : public SparcFault<FastDataAccessMMUMiss>
@@ -219,8 +219,8 @@ class FastDataAccessMMUMiss : public SparcFault<FastDataAccessMMUMiss>
     {}
     FastDataAccessMMUMiss() : vaddr(0)
     {}
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class FastDataAccessProtection : public SparcFault<FastDataAccessProtection> {};
@@ -238,8 +238,8 @@ class SpillNNormal : public EnumeratedFault<SpillNNormal>
   public:
     SpillNNormal(uint32_t n) : EnumeratedFault<SpillNNormal>(n) {;}
     // These need to be handled specially to enable spill traps in SE
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class SpillNOther : public EnumeratedFault<SpillNOther>
@@ -255,8 +255,8 @@ class FillNNormal : public EnumeratedFault<FillNNormal>
     FillNNormal(uint32_t n) : EnumeratedFault<FillNNormal>(n)
     {}
     // These need to be handled specially to enable fill traps in SE
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class FillNOther : public EnumeratedFault<FillNOther>
@@ -272,8 +272,8 @@ class TrapInstruction : public EnumeratedFault<TrapInstruction>
     TrapInstruction(uint32_t n) : EnumeratedFault<TrapInstruction>(n)
     {}
     // In SE, trap instructions are requesting services from the OS.
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 void enterREDState(ThreadContext *tc);
diff --git a/src/arch/sparc/stacktrace.hh b/src/arch/sparc/stacktrace.hh
index 1e7853d1c..c18ca4789 100644
--- a/src/arch/sparc/stacktrace.hh
+++ b/src/arch/sparc/stacktrace.hh
@@ -48,7 +48,7 @@ class StackTrace
 
   public:
     bool
-    trace(ThreadContext *tc, StaticInstPtr inst)
+    trace(ThreadContext *tc, const StaticInstPtr &inst)
     {
         panic("StackTrace::trace not implemented for SPARC.\n");
         return false;
diff --git a/src/arch/sparc/utility.hh b/src/arch/sparc/utility.hh
index bc67f5ef8..2a9fda8fe 100644
--- a/src/arch/sparc/utility.hh
+++ b/src/arch/sparc/utility.hh
@@ -87,7 +87,7 @@ void copyMiscRegs(ThreadContext *src, ThreadContext *dest);
 void skipFunction(ThreadContext *tc);
 
 inline void
-advancePC(PCState &pc, const StaticInstPtr inst)
+advancePC(PCState &pc, const StaticInstPtr &inst)
 {
     inst->advancePC(pc);
 }
diff --git a/src/arch/x86/faults.cc b/src/arch/x86/faults.cc
index 0cbf2334e..e3a4befb2 100644
--- a/src/arch/x86/faults.cc
+++ b/src/arch/x86/faults.cc
@@ -50,7 +50,7 @@
 
 namespace X86ISA
 {
-    void X86FaultBase::invoke(ThreadContext * tc, StaticInstPtr inst)
+    void X86FaultBase::invoke(ThreadContext * tc, const StaticInstPtr &inst)
     {
         if (!FullSystem) {
             FaultBase::invoke(tc, inst);
@@ -104,7 +104,7 @@ namespace X86ISA
         return ss.str();
     }
     
-    void X86Trap::invoke(ThreadContext * tc, StaticInstPtr inst)
+    void X86Trap::invoke(ThreadContext * tc, const StaticInstPtr &inst)
     {
         X86FaultBase::invoke(tc);
         if (!FullSystem)
@@ -116,13 +116,13 @@ namespace X86ISA
         pc.uEnd();
     }
 
-    void X86Abort::invoke(ThreadContext * tc, StaticInstPtr inst)
+    void X86Abort::invoke(ThreadContext * tc, const StaticInstPtr &inst)
     {
         panic("Abort exception!");
     }
 
     void
-    InvalidOpcode::invoke(ThreadContext * tc, StaticInstPtr inst)
+    InvalidOpcode::invoke(ThreadContext * tc, const StaticInstPtr &inst)
     {
         if (FullSystem) {
             X86Fault::invoke(tc, inst);
@@ -132,7 +132,7 @@ namespace X86ISA
         }
     }
 
-    void PageFault::invoke(ThreadContext * tc, StaticInstPtr inst)
+    void PageFault::invoke(ThreadContext * tc, const StaticInstPtr &inst)
     {
         if (FullSystem) {
             HandyM5Reg m5reg = tc->readMiscRegNoEffect(MISCREG_M5_REG);
@@ -170,7 +170,7 @@ namespace X86ISA
     }
 
     void
-    InitInterrupt::invoke(ThreadContext *tc, StaticInstPtr inst)
+    InitInterrupt::invoke(ThreadContext *tc, const StaticInstPtr &inst)
     {
         DPRINTF(Faults, "Init interrupt.\n");
         // The otherwise unmodified integer registers should be set to 0.
@@ -288,7 +288,7 @@ namespace X86ISA
     }
 
     void
-    StartupInterrupt::invoke(ThreadContext *tc, StaticInstPtr inst)
+    StartupInterrupt::invoke(ThreadContext *tc, const StaticInstPtr &inst)
     {
         DPRINTF(Faults, "Startup interrupt with vector %#x.\n", vector);
         HandyM5Reg m5Reg = tc->readMiscReg(MISCREG_M5_REG);
diff --git a/src/arch/x86/faults.hh b/src/arch/x86/faults.hh
index 86b633471..b43cda36a 100644
--- a/src/arch/x86/faults.hh
+++ b/src/arch/x86/faults.hh
@@ -85,8 +85,8 @@ namespace X86ISA
             return false;
         }
 
-        void invoke(ThreadContext * tc,
-                StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+        void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                    StaticInst::nullStaticInstPtr);
 
         virtual std::string describe() const;
 
@@ -120,8 +120,8 @@ namespace X86ISA
             : X86FaultBase(name, mnem, vector, _errorCode)
         {}
 
-        void invoke(ThreadContext * tc,
-                StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+        void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                    StaticInst::nullStaticInstPtr);
     };
 
     // Base class for x86 aborts which seem to be catastrophic failures.
@@ -133,8 +133,8 @@ namespace X86ISA
             : X86FaultBase(name, mnem, vector, _errorCode)
         {}
 
-        void invoke(ThreadContext * tc,
-                StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+        void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                    StaticInst::nullStaticInstPtr);
     };
 
     // Base class for x86 interrupts.
@@ -155,8 +155,8 @@ namespace X86ISA
             return "unimplemented_micro";
         }
 
-        void invoke(ThreadContext * tc,
-                StaticInstPtr inst = StaticInst::nullStaticInstPtr)
+        void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                    StaticInst::nullStaticInstPtr)
         {
             panic("Unimplemented instruction!");
         }
@@ -248,8 +248,8 @@ namespace X86ISA
             X86Fault("Invalid-Opcode", "#UD", 6)
         {}
 
-        void invoke(ThreadContext * tc,
-                StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+        void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                    StaticInst::nullStaticInstPtr);
     };
 
     class DeviceNotAvailable : public X86Fault
@@ -331,8 +331,8 @@ namespace X86ISA
             errorCode = code;
         }
 
-        void invoke(ThreadContext * tc,
-                StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+        void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                    StaticInst::nullStaticInstPtr);
 
         virtual std::string describe() const;
     };
@@ -400,8 +400,8 @@ namespace X86ISA
             X86Interrupt("INIT Interrupt", "#INIT", _vector)
         {}
 
-        void invoke(ThreadContext * tc,
-                StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+        void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                    StaticInst::nullStaticInstPtr);
     };
 
     class StartupInterrupt : public X86Interrupt
@@ -411,8 +411,8 @@ namespace X86ISA
             X86Interrupt("Startup Interrupt", "#SIPI", _vector)
         {}
 
-        void invoke(ThreadContext * tc,
-                StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+        void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                    StaticInst::nullStaticInstPtr);
     };
 
     class SoftwareInterrupt : public X86Interrupt
diff --git a/src/arch/x86/stacktrace.cc b/src/arch/x86/stacktrace.cc
index 636f74123..d887ac293 100644
--- a/src/arch/x86/stacktrace.cc
+++ b/src/arch/x86/stacktrace.cc
@@ -121,7 +121,7 @@ namespace X86ISA
     {
     }
 
-    StackTrace::StackTrace(ThreadContext *_tc, StaticInstPtr inst)
+    StackTrace::StackTrace(ThreadContext *_tc, const StaticInstPtr &inst)
         : tc(0), stack(64)
     {
         trace(_tc, inst);
diff --git a/src/arch/x86/stacktrace.hh b/src/arch/x86/stacktrace.hh
index e9d6900d8..a17f4ef80 100644
--- a/src/arch/x86/stacktrace.hh
+++ b/src/arch/x86/stacktrace.hh
@@ -75,7 +75,7 @@ namespace X86ISA
 
       public:
         StackTrace();
-        StackTrace(ThreadContext *tc, StaticInstPtr inst);
+        StackTrace(ThreadContext *tc, const StaticInstPtr &inst);
         ~StackTrace();
 
         void clear()
@@ -85,7 +85,7 @@ namespace X86ISA
         }
 
         bool valid() const { return tc != NULL; }
-        bool trace(ThreadContext *tc, StaticInstPtr inst);
+        bool trace(ThreadContext *tc, const StaticInstPtr &inst);
 
       public:
         const std::vector<Addr> &getstack() const { return stack; }
@@ -107,7 +107,7 @@ namespace X86ISA
     };
 
     inline bool
-    StackTrace::trace(ThreadContext *tc, StaticInstPtr inst)
+    StackTrace::trace(ThreadContext *tc, const StaticInstPtr &inst)
     {
         if (!inst->isCall() && !inst->isReturn())
             return false;
diff --git a/src/arch/x86/utility.hh b/src/arch/x86/utility.hh
index 046b959db..9be66d8d2 100644
--- a/src/arch/x86/utility.hh
+++ b/src/arch/x86/utility.hh
@@ -94,7 +94,7 @@ namespace X86ISA
     void skipFunction(ThreadContext *tc);
 
     inline void
-    advancePC(PCState &pc, const StaticInstPtr inst)
+    advancePC(PCState &pc, const StaticInstPtr &inst)
     {
         inst->advancePC(pc);
     }
diff --git a/src/cpu/base_dyn_inst.hh b/src/cpu/base_dyn_inst.hh
index 9346b69cc..b1ebe3f09 100644
--- a/src/cpu/base_dyn_inst.hh
+++ b/src/cpu/base_dyn_inst.hh
@@ -156,7 +156,7 @@ class BaseDynInst : public ExecContext, public RefCounted
     InstSeqNum seqNum;
 
     /** The StaticInst used by this BaseDynInst. */
-    StaticInstPtr staticInst;
+    const StaticInstPtr staticInst;
 
     /** Pointer to the Impl's CPU object. */
     ImplCPU *cpu;
@@ -204,7 +204,7 @@ class BaseDynInst : public ExecContext, public RefCounted
     TheISA::PCState predPC;
 
     /** The Macroop if one exists */
-    StaticInstPtr macroop;
+    const StaticInstPtr macroop;
 
     /** How many source registers are ready. */
     uint8_t readyRegs;
@@ -427,14 +427,14 @@ class BaseDynInst : public ExecContext, public RefCounted
      *  @param seq_num The sequence number of the instruction.
      *  @param cpu Pointer to the instruction's CPU.
      */
-    BaseDynInst(StaticInstPtr staticInst, StaticInstPtr macroop,
+    BaseDynInst(const StaticInstPtr &staticInst, const StaticInstPtr &macroop,
                 TheISA::PCState pc, TheISA::PCState predPC,
                 InstSeqNum seq_num, ImplCPU *cpu);
 
     /** BaseDynInst constructor given a StaticInst pointer.
      *  @param _staticInst The StaticInst for this BaseDynInst.
      */
-    BaseDynInst(StaticInstPtr staticInst, StaticInstPtr macroop);
+    BaseDynInst(const StaticInstPtr &staticInst, const StaticInstPtr &macroop);
 
     /** BaseDynInst destructor. */
     ~BaseDynInst();
diff --git a/src/cpu/base_dyn_inst_impl.hh b/src/cpu/base_dyn_inst_impl.hh
index 9004fc0f5..976e9ceb0 100644
--- a/src/cpu/base_dyn_inst_impl.hh
+++ b/src/cpu/base_dyn_inst_impl.hh
@@ -59,8 +59,8 @@
 #include "sim/faults.hh"
 
 template <class Impl>
-BaseDynInst<Impl>::BaseDynInst(StaticInstPtr _staticInst,
-                               StaticInstPtr _macroop,
+BaseDynInst<Impl>::BaseDynInst(const StaticInstPtr &_staticInst,
+                               const StaticInstPtr &_macroop,
                                TheISA::PCState _pc, TheISA::PCState _predPC,
                                InstSeqNum seq_num, ImplCPU *cpu)
   : staticInst(_staticInst), cpu(cpu), traceData(NULL), macroop(_macroop)
@@ -74,8 +74,8 @@ BaseDynInst<Impl>::BaseDynInst(StaticInstPtr _staticInst,
 }
 
 template <class Impl>
-BaseDynInst<Impl>::BaseDynInst(StaticInstPtr _staticInst,
-                               StaticInstPtr _macroop)
+BaseDynInst<Impl>::BaseDynInst(const StaticInstPtr &_staticInst,
+                               const StaticInstPtr &_macroop)
     : staticInst(_staticInst), traceData(NULL), macroop(_macroop)
 {
     seqNum = 0;
diff --git a/src/cpu/checker/cpu_impl.hh b/src/cpu/checker/cpu_impl.hh
index 9743905c1..b64e1bff1 100644
--- a/src/cpu/checker/cpu_impl.hh
+++ b/src/cpu/checker/cpu_impl.hh
@@ -303,7 +303,7 @@ Checker<Impl>::verify(DynInstPtr &completed_inst)
                         microcodeRom.fetchMicroop(pcState.microPC(), NULL);
                 } else if (!curMacroStaticInst) {
                     //We're not in the middle of a macro instruction
-                    StaticInstPtr instPtr = NULL;
+                    StaticInstPtr instPtr = nullptr;
 
                     //Predecode, ie bundle up an ExtMachInst
                     //If more fetch data is needed, pass it in.
diff --git a/src/cpu/exetrace.cc b/src/cpu/exetrace.cc
index 9709466b7..9e08dca00 100644
--- a/src/cpu/exetrace.cc
+++ b/src/cpu/exetrace.cc
@@ -56,7 +56,7 @@ ExeTracerRecord::dumpTicks(ostream &outs)
 }
 
 void
-Trace::ExeTracerRecord::traceInst(StaticInstPtr inst, bool ran)
+Trace::ExeTracerRecord::traceInst(const StaticInstPtr &inst, bool ran)
 {
     ostream &outs = Trace::output();
 
diff --git a/src/cpu/exetrace.hh b/src/cpu/exetrace.hh
index 6d9f2a337..ebb712af6 100644
--- a/src/cpu/exetrace.hh
+++ b/src/cpu/exetrace.hh
@@ -56,7 +56,7 @@ class ExeTracerRecord : public InstRecord
     {
     }
 
-    void traceInst(StaticInstPtr inst, bool ran);
+    void traceInst(const StaticInstPtr &inst, bool ran);
 
     void dump();
     virtual void dumpTicks(std::ostream &outs);
diff --git a/src/cpu/minor/func_unit.cc b/src/cpu/minor/func_unit.cc
index 1a75c4aa8..65dd1eefc 100644
--- a/src/cpu/minor/func_unit.cc
+++ b/src/cpu/minor/func_unit.cc
@@ -199,7 +199,7 @@ FUPipeline::advance()
 }
 
 MinorFUTiming *
-FUPipeline::findTiming(StaticInstPtr inst)
+FUPipeline::findTiming(const StaticInstPtr &inst)
 {
 #if THE_ISA == ARM_ISA
     /* This should work for any ISA with a POD mach_inst */
diff --git a/src/cpu/minor/func_unit.hh b/src/cpu/minor/func_unit.hh
index 34da579b6..d99e527e8 100644
--- a/src/cpu/minor/func_unit.hh
+++ b/src/cpu/minor/func_unit.hh
@@ -257,7 +257,7 @@ class FUPipeline : public FUPipelineBase, public FuncUnit
 
     /** Find the extra timing information for this instruction.  Returns
      *  NULL if no decode info. is found */
-    MinorFUTiming *findTiming(StaticInstPtr inst);
+    MinorFUTiming *findTiming(const StaticInstPtr &inst);
 
     /** Step the pipeline.  Allow multiple steps? */
     void advance();
diff --git a/src/cpu/o3/cpu.cc b/src/cpu/o3/cpu.cc
index 7ed3944cf..925b3d2d8 100644
--- a/src/cpu/o3/cpu.cc
+++ b/src/cpu/o3/cpu.cc
@@ -946,12 +946,13 @@ FullO3CPU<Impl>::processInterrupts(const Fault &interrupt)
     this->interrupts->updateIntrInfo(this->threadContexts[0]);
 
     DPRINTF(O3CPU, "Interrupt %s being handled\n", interrupt->name());
-    this->trap(interrupt, 0, NULL);
+    this->trap(interrupt, 0, nullptr);
 }
 
 template <class Impl>
 void
-FullO3CPU<Impl>::trap(const Fault &fault, ThreadID tid, StaticInstPtr inst)
+FullO3CPU<Impl>::trap(const Fault &fault, ThreadID tid,
+                      const StaticInstPtr &inst)
 {
     // Pass the thread's TC into the invoke method.
     fault->invoke(this->threadContexts[tid], inst);
diff --git a/src/cpu/o3/cpu.hh b/src/cpu/o3/cpu.hh
index c263790ce..96cd071e4 100644
--- a/src/cpu/o3/cpu.hh
+++ b/src/cpu/o3/cpu.hh
@@ -376,7 +376,7 @@ class FullO3CPU : public BaseO3CPU
     { return globalSeqNum++; }
 
     /** Traps to handle given fault. */
-    void trap(const Fault &fault, ThreadID tid, StaticInstPtr inst);
+    void trap(const Fault &fault, ThreadID tid, const StaticInstPtr &inst);
 
     /** HW return from error interrupt. */
     Fault hwrei(ThreadID tid);
diff --git a/src/cpu/o3/dyn_inst.hh b/src/cpu/o3/dyn_inst.hh
index ea961092d..80d502f0e 100644
--- a/src/cpu/o3/dyn_inst.hh
+++ b/src/cpu/o3/dyn_inst.hh
@@ -83,12 +83,13 @@ class BaseO3DynInst : public BaseDynInst<Impl>
 
   public:
     /** BaseDynInst constructor given a binary instruction. */
-    BaseO3DynInst(StaticInstPtr staticInst, StaticInstPtr macroop,
+    BaseO3DynInst(const StaticInstPtr &staticInst, const StaticInstPtr &macroop,
                   TheISA::PCState pc, TheISA::PCState predPC,
                   InstSeqNum seq_num, O3CPU *cpu);
 
     /** BaseDynInst constructor given a static inst pointer. */
-    BaseO3DynInst(StaticInstPtr _staticInst, StaticInstPtr _macroop);
+    BaseO3DynInst(const StaticInstPtr &_staticInst,
+                  const StaticInstPtr &_macroop);
 
     ~BaseO3DynInst();
 
diff --git a/src/cpu/o3/dyn_inst_impl.hh b/src/cpu/o3/dyn_inst_impl.hh
index e51054f8d..fa3ce28fa 100644
--- a/src/cpu/o3/dyn_inst_impl.hh
+++ b/src/cpu/o3/dyn_inst_impl.hh
@@ -49,8 +49,8 @@
 #include "debug/O3PipeView.hh"
 
 template <class Impl>
-BaseO3DynInst<Impl>::BaseO3DynInst(StaticInstPtr staticInst,
-                                   StaticInstPtr macroop,
+BaseO3DynInst<Impl>::BaseO3DynInst(const StaticInstPtr &staticInst,
+                                   const StaticInstPtr &macroop,
                                    TheISA::PCState pc, TheISA::PCState predPC,
                                    InstSeqNum seq_num, O3CPU *cpu)
     : BaseDynInst<Impl>(staticInst, macroop, pc, predPC, seq_num, cpu)
@@ -59,8 +59,8 @@ BaseO3DynInst<Impl>::BaseO3DynInst(StaticInstPtr staticInst,
 }
 
 template <class Impl>
-BaseO3DynInst<Impl>::BaseO3DynInst(StaticInstPtr _staticInst,
-                                   StaticInstPtr _macroop)
+BaseO3DynInst<Impl>::BaseO3DynInst(const StaticInstPtr &_staticInst,
+                                   const StaticInstPtr &_macroop)
     : BaseDynInst<Impl>(_staticInst, _macroop)
 {
     initVars();
diff --git a/src/cpu/pred/bpred_unit.hh b/src/cpu/pred/bpred_unit.hh
index f75ab79d5..bca64cce0 100644
--- a/src/cpu/pred/bpred_unit.hh
+++ b/src/cpu/pred/bpred_unit.hh
@@ -87,9 +87,9 @@ class BPredUnit : public SimObject
      * @param tid The thread id.
      * @return Returns if the branch is taken or not.
      */
-    bool predict(StaticInstPtr &inst, const InstSeqNum &seqNum,
+    bool predict(const StaticInstPtr &inst, const InstSeqNum &seqNum,
                  TheISA::PCState &pc, ThreadID tid);
-    bool predictInOrder(StaticInstPtr &inst, const InstSeqNum &seqNum,
+    bool predictInOrder(const StaticInstPtr &inst, const InstSeqNum &seqNum,
                         int asid, TheISA::PCState &instPC,
                         TheISA::PCState &predPC, ThreadID tid);
 
diff --git a/src/cpu/pred/bpred_unit_impl.hh b/src/cpu/pred/bpred_unit_impl.hh
index eaffb7ea1..53ec808b6 100644
--- a/src/cpu/pred/bpred_unit_impl.hh
+++ b/src/cpu/pred/bpred_unit_impl.hh
@@ -129,7 +129,7 @@ BPredUnit::drainSanityCheck() const
 }
 
 bool
-BPredUnit::predict(StaticInstPtr &inst, const InstSeqNum &seqNum,
+BPredUnit::predict(const StaticInstPtr &inst, const InstSeqNum &seqNum,
                    TheISA::PCState &pc, ThreadID tid)
 {
     // See if branch predictor predicts taken.
@@ -244,7 +244,7 @@ BPredUnit::predict(StaticInstPtr &inst, const InstSeqNum &seqNum,
 }
 
 bool
-BPredUnit::predictInOrder(StaticInstPtr &inst, const InstSeqNum &seqNum,
+BPredUnit::predictInOrder(const StaticInstPtr &inst, const InstSeqNum &seqNum,
                           int asid, TheISA::PCState &instPC,
                           TheISA::PCState &predPC, ThreadID tid)
 {
diff --git a/src/cpu/profile.hh b/src/cpu/profile.hh
index 8fb0e3a8e..9d683959c 100644
--- a/src/cpu/profile.hh
+++ b/src/cpu/profile.hh
@@ -73,7 +73,7 @@ class FunctionProfile
     FunctionProfile(const SymbolTable *symtab);
     ~FunctionProfile();
 
-    ProfileNode *consume(ThreadContext *tc, StaticInstPtr inst);
+    ProfileNode *consume(ThreadContext *tc, const StaticInstPtr &inst);
     ProfileNode *consume(const std::vector<Addr> &stack);
     void clear();
     void dump(ThreadContext *tc, std::ostream &out) const;
@@ -81,7 +81,7 @@ class FunctionProfile
 };
 
 inline ProfileNode *
-FunctionProfile::consume(ThreadContext *tc, StaticInstPtr inst)
+FunctionProfile::consume(ThreadContext *tc, const StaticInstPtr &inst)
 {
     if (!trace.trace(tc, inst))
         return NULL;
diff --git a/src/cpu/simple/probes/simpoint.cc b/src/cpu/simple/probes/simpoint.cc
index 22eaad086..f2c0be62b 100644
--- a/src/cpu/simple/probes/simpoint.cc
+++ b/src/cpu/simple/probes/simpoint.cc
@@ -77,7 +77,7 @@ void
 SimPoint::profile(const std::pair<SimpleThread*, StaticInstPtr>& p)
 {
     SimpleThread* thread = p.first;
-    StaticInstPtr inst = p.second;
+    const StaticInstPtr &inst = p.second;
 
     if (!currentBBVInstCount)
         currentBBV.first = thread->pcState().instAddr();
diff --git a/src/cpu/timing_expr.cc b/src/cpu/timing_expr.cc
index d6d904956..36a643ed2 100644
--- a/src/cpu/timing_expr.cc
+++ b/src/cpu/timing_expr.cc
@@ -40,7 +40,7 @@
 #include "base/intmath.hh"
 #include "cpu/timing_expr.hh"
 
-TimingExprEvalContext::TimingExprEvalContext (StaticInstPtr inst_,
+TimingExprEvalContext::TimingExprEvalContext(const StaticInstPtr &inst_,
     ThreadContext *thread_,
     TimingExprLet *let_) :
     inst(inst_), thread(thread_), let(let_)
diff --git a/src/cpu/timing_expr.hh b/src/cpu/timing_expr.hh
index d2c38ea90..0ec189437 100644
--- a/src/cpu/timing_expr.hh
+++ b/src/cpu/timing_expr.hh
@@ -73,7 +73,7 @@ class TimingExprEvalContext
 {
   public:
     /** Special visible context */
-    StaticInstPtr inst;
+    const StaticInstPtr &inst;
     ThreadContext *thread;
 
     /** Context visible as sub expressions.  results will hold the results
@@ -83,7 +83,7 @@ class TimingExprEvalContext
     std::vector<uint64_t> results;
     std::vector<bool > resultAvailable;
 
-    TimingExprEvalContext(StaticInstPtr inst_,
+    TimingExprEvalContext(const StaticInstPtr &inst_,
         ThreadContext *thread_, TimingExprLet *let_);
 };
 
diff --git a/src/sim/faults.cc b/src/sim/faults.cc
index c409aa95b..e2562fca6 100644
--- a/src/sim/faults.cc
+++ b/src/sim/faults.cc
@@ -39,7 +39,7 @@
 #include "sim/full_system.hh"
 #include "sim/process.hh"
 
-void FaultBase::invoke(ThreadContext * tc, StaticInstPtr inst)
+void FaultBase::invoke(ThreadContext * tc, const StaticInstPtr &inst)
 {
     if (FullSystem) {
         DPRINTF(Fault, "Fault %s at PC: %s\n", name(), tc->pcState());
@@ -49,17 +49,17 @@ void FaultBase::invoke(ThreadContext * tc, StaticInstPtr inst)
     }
 }
 
-void UnimpFault::invoke(ThreadContext * tc, StaticInstPtr inst)
+void UnimpFault::invoke(ThreadContext * tc, const StaticInstPtr &inst)
 {
     panic("Unimpfault: %s\n", panicStr.c_str());
 }
 
-void ReExec::invoke(ThreadContext *tc, StaticInstPtr inst)
+void ReExec::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     tc->pcState(tc->pcState());
 }
 
-void GenericPageTableFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+void GenericPageTableFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     bool handled = false;
     if (!FullSystem) {
@@ -71,7 +71,7 @@ void GenericPageTableFault::invoke(ThreadContext *tc, StaticInstPtr inst)
 
 }
 
-void GenericAlignmentFault::invoke(ThreadContext *tc, StaticInstPtr inst)
+void GenericAlignmentFault::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
     panic("Alignment fault when accessing virtual address %#x\n", vaddr);
 }
diff --git a/src/sim/faults.hh b/src/sim/faults.hh
index 4cdb24aee..0377c0893 100644
--- a/src/sim/faults.hh
+++ b/src/sim/faults.hh
@@ -54,8 +54,8 @@ class FaultBase : public RefCounted
 {
   public:
     virtual FaultName name() const = 0;
-    virtual void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    virtual void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                        StaticInst::nullStaticInstPtr);
 };
 
 class UnimpFault : public FaultBase
@@ -68,8 +68,8 @@ class UnimpFault : public FaultBase
     { }
 
     FaultName name() const {return "Unimplemented simulator feature";}
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class ReExec : public FaultBase
@@ -77,8 +77,8 @@ class ReExec : public FaultBase
   public:
     virtual FaultName name() const { return "Re-execution fault";}
     ReExec() {}
-    void invoke(ThreadContext *tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class GenericPageTableFault : public FaultBase
@@ -88,8 +88,8 @@ class GenericPageTableFault : public FaultBase
   public:
     FaultName name() const {return "Generic page table fault";}
     GenericPageTableFault(Addr va) : vaddr(va) {}
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 class GenericAlignmentFault : public FaultBase
@@ -99,8 +99,8 @@ class GenericAlignmentFault : public FaultBase
   public:
     FaultName name() const {return "Generic alignment fault";}
     GenericAlignmentFault(Addr va) : vaddr(va) {}
-    void invoke(ThreadContext * tc,
-            StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+    void invoke(ThreadContext * tc, const StaticInstPtr &inst =
+                StaticInst::nullStaticInstPtr);
 };
 
 #endif // __FAULTS_HH__