InOrder: Import new inorder CPU model from MIPS.

This model currently only works in MIPS_SE mode, so it will take some effort
to clean it up and make it generally useful. Hopefully people are willing to
help make that happen!

1 files changed, 258 insertions, 0 deletions

diff --git a/src/cpu/inorder/resources/bpred_unit.hh b/src/cpu/inorder/resources/bpred_unit.hh
new file mode 100644
index 000000000..b945922a7
--- /dev/null
+++ b/src/cpu/inorder/resources/bpred_unit.hh
@@ -0,0 +1,258 @@
+/*
+ * Copyright (c) 2004-2005 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Kevin Lim
+ *          Korey Sewell
+ */
+
+#ifndef __CPU_INORDER_BPRED_UNIT_HH__
+#define __CPU_INORDER_BPRED_UNIT_HH__
+
+// For Addr type.
+#include "arch/isa_traits.hh"
+#include "base/statistics.hh"
+#include "cpu/inst_seq.hh"
+
+//#include "cpu/inorder/params.hh"
+#include "cpu/o3/2bit_local_pred.hh"
+#include "cpu/o3/btb.hh"
+#include "cpu/o3/ras.hh"
+#include "cpu/o3/tournament_pred.hh"
+#include "params/InOrderCPU.hh"
+#include "cpu/inorder/inorder_dyn_inst.hh"
+#include "cpu/inorder/pipeline_traits.hh"
+
+#include <list>
+
+/**
+ * Basically a wrapper class to hold both the branch predictor
+ * and the BTB.
+ */
+class BPredUnit
+{
+  private:
+
+    enum PredType {
+        Local,
+        Tournament
+    };
+
+    PredType predictor;
+
+  public:
+
+    /**
+     * @param params The params object, that has the size of the BP and BTB.
+     */
+    BPredUnit(ThePipeline::Params *params);
+
+    /**
+     * Registers statistics.
+     */
+    void regStats();
+
+    void switchOut();
+
+    void takeOverFrom();
+
+    /**
+     * Predicts whether or not the instruction is a taken branch, and the
+     * target of the branch if it is taken.
+     * @param inst The branch instruction.
+     * @param PC The predicted PC is passed back through this parameter.
+     * @param tid The thread id.
+     * @return Returns if the branch is taken or not.
+     */
+    bool predict(ThePipeline::DynInstPtr &inst, Addr &PC, unsigned tid);
+
+    // @todo: Rename this function.
+    void BPUncond(void * &bp_history);
+
+    /**
+     * Tells the branch predictor to commit any updates until the given
+     * sequence number.
+     * @param done_sn The sequence number to commit any older updates up until.
+     * @param tid The thread id.
+     */
+    void update(const InstSeqNum &done_sn, unsigned tid);
+
+    /**
+     * Squashes all outstanding updates until a given sequence number.
+     * @param squashed_sn The sequence number to squash any younger updates up
+     * until.
+     * @param tid The thread id.
+     */
+    void squash(const InstSeqNum &squashed_sn, unsigned tid);
+
+    /**
+     * Squashes all outstanding updates until a given sequence number, and
+     * corrects that sn's update with the proper address and taken/not taken.
+     * @param squashed_sn The sequence number to squash any younger updates up
+     * until.
+     * @param corr_target The correct branch target.
+     * @param actually_taken The correct branch direction.
+     * @param tid The thread id.
+     */
+    void squash(const InstSeqNum &squashed_sn, const Addr &corr_target,
+                bool actually_taken, unsigned tid);
+
+    /**
+     * @param bp_history Pointer to the history object.  The predictor
+     * will need to update any state and delete the object.
+     */
+    void BPSquash(void *bp_history);
+
+    /**
+     * Looks up a given PC in the BP to see if it is taken or not taken.
+     * @param inst_PC The PC to look up.
+     * @param bp_history Pointer that will be set to an object that
+     * has the branch predictor state associated with the lookup.
+     * @return Whether the branch is taken or not taken.
+     */
+    bool BPLookup(Addr &inst_PC, void * &bp_history);
+
+    /**
+     * Looks up a given PC in the BTB to see if a matching entry exists.
+     * @param inst_PC The PC to look up.
+     * @return Whether the BTB contains the given PC.
+     */
+    bool BTBValid(Addr &inst_PC)
+    { return BTB.valid(inst_PC, 0); }
+
+    /**
+     * Looks up a given PC in the BTB to get the predicted target.
+     * @param inst_PC The PC to look up.
+     * @return The address of the target of the branch.
+     */
+    Addr BTBLookup(Addr &inst_PC)
+    { return BTB.lookup(inst_PC, 0); }
+
+    /**
+     * Updates the BP with taken/not taken information.
+     * @param inst_PC The branch's PC that will be updated.
+     * @param taken Whether the branch was taken or not taken.
+     * @param bp_history Pointer to the branch predictor state that is
+     * associated with the branch lookup that is being updated.
+     * @todo Make this update flexible enough to handle a global predictor.
+     */
+    void BPUpdate(Addr &inst_PC, bool taken, void *bp_history);
+
+    /**
+     * Updates the BTB with the target of a branch.
+     * @param inst_PC The branch's PC that will be updated.
+     * @param target_PC The branch's target that will be added to the BTB.
+     */
+    void BTBUpdate(Addr &inst_PC, Addr &target_PC)
+    { BTB.update(inst_PC, target_PC,0); }
+
+    void dump();
+
+  private:
+    struct PredictorHistory {
+        /**
+         * Makes a predictor history struct that contains any
+         * information needed to update the predictor, BTB, and RAS.
+         */
+        PredictorHistory(const InstSeqNum &seq_num, const Addr &inst_PC,
+                         const bool pred_taken, void *bp_history,
+                         const unsigned _tid)
+            : seqNum(seq_num), PC(inst_PC), RASTarget(0),
+              RASIndex(0), tid(_tid), predTaken(pred_taken), usedRAS(0),
+              wasCall(0), bpHistory(bp_history)
+        { }
+
+        /** The sequence number for the predictor history entry. */
+        InstSeqNum seqNum;
+
+        /** The PC associated with the sequence number. */
+        Addr PC;
+
+        /** The RAS target (only valid if a return). */
+        Addr RASTarget;
+
+        /** The RAS index of the instruction (only valid if a call). */
+        unsigned RASIndex;
+
+        /** The thread id. */
+        unsigned tid;
+
+        /** Whether or not it was predicted taken. */
+        bool predTaken;
+
+        /** Whether or not the RAS was used. */
+        bool usedRAS;
+
+        /** Whether or not the instruction was a call. */
+        bool wasCall;
+
+        /** Pointer to the history object passed back from the branch
+         * predictor.  It is used to update or restore state of the
+         * branch predictor.
+         */
+        void *bpHistory;
+    };
+
+    typedef std::list<PredictorHistory> History;
+
+    /**
+     * The per-thread predictor history. This is used to update the predictor
+     * as instructions are committed, or restore it to the proper state after
+     * a squash.
+     */
+    History predHist[ThePipeline::MaxThreads];
+
+    /** The local branch predictor. */
+    LocalBP *localBP;
+
+    /** The tournament branch predictor. */
+    TournamentBP *tournamentBP;
+
+    /** The BTB. */
+    DefaultBTB BTB;
+
+    /** The per-thread return address stack. */
+    ReturnAddrStack RAS[ThePipeline::MaxThreads];
+
+    /** Stat for number of BP lookups. */
+    Stats::Scalar<> lookups;
+    /** Stat for number of conditional branches predicted. */
+    Stats::Scalar<> condPredicted;
+    /** Stat for number of conditional branches predicted incorrectly. */
+    Stats::Scalar<> condIncorrect;
+    /** Stat for number of BTB lookups. */
+    Stats::Scalar<> BTBLookups;
+    /** Stat for number of BTB hits. */
+    Stats::Scalar<> BTBHits;
+    /** Stat for number of times the BTB is correct. */
+    Stats::Scalar<> BTBCorrect;
+    /** Stat for number of times the RAS is used to get a target. */
+    Stats::Scalar<> usedRAS;
+    /** Stat for number of times the RAS is incorrect. */
+    Stats::Scalar<> RASIncorrect;
+};
+
+#endif // __CPU_INORDER_BPRED_UNIT_HH__