cpu: Add branch predictor PMU probe points
This changeset adds probe points that can be used to implement PMU counters for branch predictor stats. The following probes are supported: * BPRedUnit::ppBranches / Branches * BPRedUnit::ppMisses / Misses
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2 changed files with 51 additions and 0 deletions
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@ -56,6 +56,7 @@
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#include "cpu/inst_seq.hh"
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#include "cpu/static_inst.hh"
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#include "params/BranchPredictor.hh"
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#include "sim/probe/pmu.hh"
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#include "sim/sim_object.hh"
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/**
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@ -76,6 +77,8 @@ class BPredUnit : public SimObject
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*/
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void regStats();
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void regProbePoints() M5_ATTR_OVERRIDE;
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/** Perform sanity checks after a drain. */
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void drainSanityCheck() const;
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@ -290,6 +293,34 @@ class BPredUnit : public SimObject
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Stats::Scalar usedRAS;
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/** Stat for number of times the RAS is incorrect. */
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Stats::Scalar RASIncorrect;
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protected:
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/**
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* @{
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* @name PMU Probe points.
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*/
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/**
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* Helper method to instantiate probe points belonging to this
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* object.
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*
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* @param name Name of the probe point.
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* @return A unique_ptr to the new probe point.
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*/
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ProbePoints::PMUUPtr pmuProbePoint(const char *name);
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/**
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* Branches seen by the branch predictor
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*
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* @note This counter includes speculative branches.
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*/
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ProbePoints::PMUUPtr ppBranches;
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/** Miss-predicted branches */
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ProbePoints::PMUUPtr ppMisses;
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/** @} */
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};
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#endif // __CPU_PRED_BPRED_UNIT_HH__
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@ -119,6 +119,22 @@ BPredUnit::regStats()
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;
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}
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ProbePoints::PMUUPtr
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BPredUnit::pmuProbePoint(const char *name)
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{
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ProbePoints::PMUUPtr ptr;
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ptr.reset(new ProbePoints::PMU(getProbeManager(), name));
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return ptr;
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}
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void
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BPredUnit::regProbePoints()
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{
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ppBranches = pmuProbePoint("Branches");
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ppMisses = pmuProbePoint("Misses");
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}
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void
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BPredUnit::drainSanityCheck() const
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{
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@ -141,6 +157,7 @@ BPredUnit::predict(const StaticInstPtr &inst, const InstSeqNum &seqNum,
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TheISA::PCState target = pc;
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++lookups;
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ppBranches->notify(1);
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void *bp_history = NULL;
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@ -259,6 +276,8 @@ BPredUnit::predictInOrder(const StaticInstPtr &inst, const InstSeqNum &seqNum,
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TheISA::PCState target;
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++lookups;
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ppBranches->notify(1);
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DPRINTF(Branch, "[tid:%i] [sn:%i] %s ... PC %s doing branch "
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"prediction\n", tid, seqNum,
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inst->disassemble(instPC.instAddr()), instPC);
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@ -438,6 +457,7 @@ BPredUnit::squash(const InstSeqNum &squashed_sn,
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History &pred_hist = predHist[tid];
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++condIncorrect;
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ppMisses->notify(1);
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DPRINTF(Branch, "[tid:%i]: Squashing from sequence number %i, "
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"setting target to %s.\n", tid, squashed_sn, corrTarget);
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