cpu: Add an indirect branch target predictor

This patch adds a configurable indirect branch predictor that can be indexed
by a combination of GHR and path history hashes. Implements the functionality
described in:

"Target prediction for indirect jumps" by Chang, Hao, and Patt
http://dl.acm.org/citation.cfm?id=264209

10 files changed, 428 insertions, 29 deletions

diff --git a/src/cpu/pred/BranchPredictor.py b/src/cpu/pred/BranchPredictor.py
index 5c52fb65e..2d7d0d0e2 100644
--- a/src/cpu/pred/BranchPredictor.py
+++ b/src/cpu/pred/BranchPredictor.py
@@ -42,6 +42,16 @@ class BranchPredictor(SimObject):
     RASSize = Param.Unsigned(16, "RAS size")
     instShiftAmt = Param.Unsigned(2, "Number of bits to shift instructions by")
 
+    useIndirect = Param.Bool(True, "Use indirect branch predictor")
+    indirectHashGHR = Param.Bool(True, "Hash branch predictor GHR")
+    indirectHashTargets = Param.Bool(True, "Hash path history targets")
+    indirectSets = Param.Unsigned(256, "Cache sets for indirect predictor")
+    indirectWays = Param.Unsigned(2, "Ways for indirect predictor")
+    indirectTagSize = Param.Unsigned(16, "Indirect target cache tag bits")
+    indirectPathLength = Param.Unsigned(3,
+        "Previous indirect targets to use for path history")
+
+
 
 class LocalBP(BranchPredictor):
     type = 'LocalBP'
diff --git a/src/cpu/pred/SConscript b/src/cpu/pred/SConscript
index 1bf94712d..dca5e8d88 100644
--- a/src/cpu/pred/SConscript
+++ b/src/cpu/pred/SConscript
@@ -35,9 +35,11 @@ if env['TARGET_ISA'] == 'null':
 
 SimObject('BranchPredictor.py')
 
+DebugFlag('Indirect')
 Source('bpred_unit.cc')
 Source('2bit_local.cc')
 Source('btb.cc')
+Source('indirect.cc')
 Source('ras.cc')
 Source('tournament.cc')
 Source ('bi_mode.cc')
diff --git a/src/cpu/pred/bi_mode.cc b/src/cpu/pred/bi_mode.cc
index c2a41cd4d..bc974bac8 100644
--- a/src/cpu/pred/bi_mode.cc
+++ b/src/cpu/pred/bi_mode.cc
@@ -236,6 +236,12 @@ BiModeBP::retireSquashed(void *bp_history)
     delete history;
 }
 
+unsigned
+BiModeBP::getGHR(void *bp_history) const
+{
+    return static_cast<BPHistory*>(bp_history)->globalHistoryReg;
+}
+
 void
 BiModeBP::updateGlobalHistReg(bool taken)
 {
diff --git a/src/cpu/pred/bi_mode.hh b/src/cpu/pred/bi_mode.hh
index da7c49f46..120a6ffd9 100644
--- a/src/cpu/pred/bi_mode.hh
+++ b/src/cpu/pred/bi_mode.hh
@@ -63,6 +63,7 @@ class BiModeBP : public BPredUnit
     void btbUpdate(Addr branch_addr, void * &bp_history);
     void update(Addr branch_addr, bool taken, void *bp_history, bool squashed);
     void retireSquashed(void *bp_history);
+    unsigned getGHR(void *bp_history) const;
 
   private:
     void updateGlobalHistReg(bool taken);
diff --git a/src/cpu/pred/bpred_unit.cc b/src/cpu/pred/bpred_unit.cc
index c38927c8d..43ac8a608 100644
--- a/src/cpu/pred/bpred_unit.cc
+++ b/src/cpu/pred/bpred_unit.cc
@@ -62,6 +62,15 @@ BPredUnit::BPredUnit(const Params *params)
           params->instShiftAmt,
           params->numThreads),
       RAS(numThreads),
+      useIndirect(params->useIndirect),
+      iPred(params->indirectHashGHR,
+            params->indirectHashTargets,
+            params->indirectSets,
+            params->indirectWays,
+            params->indirectTagSize,
+            params->indirectPathLength,
+            params->instShiftAmt,
+            params->numThreads),
       instShiftAmt(params->instShiftAmt)
 {
     for (auto& r : RAS)
@@ -117,6 +126,27 @@ BPredUnit::regStats()
         .name(name() + ".RASInCorrect")
         .desc("Number of incorrect RAS predictions.")
         ;
+
+    indirectLookups
+        .name(name() + ".indirectLookups")
+        .desc("Number of indirect predictor lookups.")
+        ;
+
+    indirectHits
+        .name(name() + ".indirectHits")
+        .desc("Number of indirect target hits.")
+        ;
+
+    indirectMisses
+        .name(name() + ".indirectMisses")
+        .desc("Number of indirect misses.")
+        ;
+
+    indirectMispredicted
+        .name(name() + "indirectMispredcited")
+        .desc("Number of mispredicted indirect branches.")
+        ;
+
 }
 
 ProbePoints::PMUUPtr
@@ -216,31 +246,59 @@ BPredUnit::predict(const StaticInstPtr &inst, const InstSeqNum &seqNum,
                         tid, pc, pc, RAS[tid].topIdx());
             }
 
-            if (BTB.valid(pc.instAddr(), tid)) {
-                ++BTBHits;
-
-                // If it's not a return, use the BTB to get the target addr.
-                target = BTB.lookup(pc.instAddr(), tid);
-
-                DPRINTF(Branch, "[tid:%i]: Instruction %s predicted"
-                        " target is %s.\n", tid, pc, target);
-
+            if (inst->isDirectCtrl() || !useIndirect) {
+                // Check BTB on direct branches
+                if (BTB.valid(pc.instAddr(), tid)) {
+                    ++BTBHits;
+
+                    // If it's not a return, use the BTB to get target addr.
+                    target = BTB.lookup(pc.instAddr(), tid);
+
+                    DPRINTF(Branch, "[tid:%i]: Instruction %s predicted"
+                            " target is %s.\n", tid, pc, target);
+
+                } else {
+                    DPRINTF(Branch, "[tid:%i]: BTB doesn't have a "
+                            "valid entry.\n",tid);
+                    pred_taken = false;
+                    // The Direction of the branch predictor is altered
+                    // because the BTB did not have an entry
+                    // The predictor needs to be updated accordingly
+                    if (!inst->isCall() && !inst->isReturn()) {
+                        btbUpdate(pc.instAddr(), bp_history);
+                        DPRINTF(Branch, "[tid:%i]:[sn:%i] btbUpdate"
+                                " called for %s\n", tid, seqNum, pc);
+                    } else if (inst->isCall() && !inst->isUncondCtrl()) {
+                        RAS[tid].pop();
+                        predict_record.pushedRAS = false;
+                    }
+                    TheISA::advancePC(target, inst);
+                }
             } else {
-                DPRINTF(Branch, "[tid:%i]: BTB doesn't have a "
-                        "valid entry.\n",tid);
-                pred_taken = false;
-                // The Direction of the branch predictor is altered because the
-                // BTB did not have an entry
-                // The predictor needs to be updated accordingly
-                if (!inst->isCall() && !inst->isReturn()) {
-                      btbUpdate(pc.instAddr(), bp_history);
-                      DPRINTF(Branch, "[tid:%i]:[sn:%i] btbUpdate"
-                              " called for %s\n", tid, seqNum, pc);
-                } else if (inst->isCall() && !inst->isUncondCtrl()) {
-                      RAS[tid].pop();
-                      predict_record.pushedRAS = false;
+                predict_record.wasIndirect = true;
+                ++indirectLookups;
+                //Consult indirect predictor on indirect control
+                if (iPred.lookup(pc.instAddr(), getGHR(bp_history), target,
+                        tid)) {
+                    // Indirect predictor hit
+                    ++indirectHits;
+                    DPRINTF(Branch, "[tid:%i]: Instruction %s predicted "
+                            "indirect target is %s.\n", tid, pc, target);
+                } else {
+                    ++indirectMisses;
+                    pred_taken = false;
+                    DPRINTF(Branch, "[tid:%i]: Instruction %s no indirect "
+                            "target.\n", tid, pc);
+                    if (!inst->isCall() && !inst->isReturn()) {
+
+                    } else if (inst->isCall() && !inst->isUncondCtrl()) {
+                        RAS[tid].pop();
+                        predict_record.pushedRAS = false;
+                    }
+                    TheISA::advancePC(target, inst);
                 }
-                TheISA::advancePC(target, inst);
+                iPred.recordIndirect(pc.instAddr(), target.instAddr(), seqNum,
+                        tid);
             }
         }
     } else {
@@ -388,6 +446,7 @@ BPredUnit::update(const InstSeqNum &done_sn, ThreadID tid)
     DPRINTF(Branch, "[tid:%i]: Committing branches until "
             "[sn:%lli].\n", tid, done_sn);
 
+    iPred.commit(done_sn, tid);
     while (!predHist[tid].empty() &&
            predHist[tid].back().seqNum <= done_sn) {
         // Update the branch predictor with the correct results.
@@ -407,6 +466,7 @@ BPredUnit::squash(const InstSeqNum &squashed_sn, ThreadID tid)
 {
     History &pred_hist = predHist[tid];
 
+    iPred.squash(squashed_sn, tid);
     while (!pred_hist.empty() &&
            pred_hist.front().seqNum > squashed_sn) {
         if (pred_hist.front().usedRAS) {
@@ -485,8 +545,13 @@ BPredUnit::squash(const InstSeqNum &squashed_sn,
 
         if ((*hist_it).usedRAS) {
             ++RASIncorrect;
+            DPRINTF(Branch, "[tid:%i]: Incorrect RAS [sn:%i]\n",
+                    tid, hist_it->seqNum);
         }
 
+        // Have to get GHR here because the update deletes bpHistory
+        unsigned ghr = getGHR(hist_it->bpHistory);
+
         update((*hist_it).pc, actually_taken,
                pred_hist.front().bpHistory, true);
         hist_it->wasSquashed = true;
@@ -499,12 +564,15 @@ BPredUnit::squash(const InstSeqNum &squashed_sn,
                  RAS[tid].pop();
                  hist_it->usedRAS = true;
             }
+            if (hist_it->wasIndirect) {
+                ++indirectMispredicted;
+                iPred.recordTarget(hist_it->seqNum, ghr, corrTarget, tid);
+            } else {
+                DPRINTF(Branch,"[tid: %i] BTB Update called for [sn:%i]"
+                        " PC: %s\n", tid,hist_it->seqNum, hist_it->pc);
 
-            DPRINTF(Branch,"[tid: %i] BTB Update called for [sn:%i]"
-                    " PC: %s\n", tid,hist_it->seqNum, hist_it->pc);
-
-            BTB.update((*hist_it).pc, corrTarget, tid);
-
+                BTB.update((*hist_it).pc, corrTarget, tid);
+            }
         } else {
            //Actually not Taken
            if (hist_it->usedRAS) {
diff --git a/src/cpu/pred/bpred_unit.hh b/src/cpu/pred/bpred_unit.hh
index bef8cb949..fb10a8bee 100644
--- a/src/cpu/pred/bpred_unit.hh
+++ b/src/cpu/pred/bpred_unit.hh
@@ -52,6 +52,7 @@
 #include "base/statistics.hh"
 #include "base/types.hh"
 #include "cpu/pred/btb.hh"
+#include "cpu/pred/indirect.hh"
 #include "cpu/pred/ras.hh"
 #include "cpu/inst_seq.hh"
 #include "cpu/static_inst.hh"
@@ -197,6 +198,9 @@ class BPredUnit : public SimObject
     void BTBUpdate(Addr instPC, const TheISA::PCState &target)
     { BTB.update(instPC, target, 0); }
 
+
+    virtual unsigned getGHR(void* bp_history) const { return 0; }
+
     void dump();
 
   private:
@@ -210,7 +214,7 @@ class BPredUnit : public SimObject
                          ThreadID _tid)
             : seqNum(seq_num), pc(instPC), bpHistory(bp_history), RASTarget(0),
               RASIndex(0), tid(_tid), predTaken(pred_taken), usedRAS(0), pushedRAS(0),
-              wasCall(0), wasReturn(0), wasSquashed(0)
+              wasCall(0), wasReturn(0), wasSquashed(0), wasIndirect(0)
         {}
 
         bool operator==(const PredictorHistory &entry) const {
@@ -255,6 +259,9 @@ class BPredUnit : public SimObject
 
         /** Whether this instruction has already mispredicted/updated bp */
         bool wasSquashed;
+
+        /** Wether this instruction was an indirect branch */
+        bool wasIndirect;
     };
 
     typedef std::deque<PredictorHistory> History;
@@ -276,6 +283,12 @@ class BPredUnit : public SimObject
     /** The per-thread return address stack. */
     std::vector<ReturnAddrStack> RAS;
 
+    /** Option to disable indirect predictor. */
+    const bool useIndirect;
+
+    /** The indirect target predictor. */
+    IndirectPredictor iPred;
+
     /** Stat for number of BP lookups. */
     Stats::Scalar lookups;
     /** Stat for number of conditional branches predicted. */
@@ -295,6 +308,15 @@ class BPredUnit : public SimObject
     /** Stat for number of times the RAS is incorrect. */
     Stats::Scalar RASIncorrect;
 
+    /** Stat for the number of indirect target lookups.*/
+    Stats::Scalar indirectLookups;
+    /** Stat for the number of indirect target hits.*/
+    Stats::Scalar indirectHits;
+    /** Stat for the number of indirect target misses.*/
+    Stats::Scalar indirectMisses;
+    /** Stat for the number of indirect target mispredictions.*/
+    Stats::Scalar indirectMispredicted;
+
   protected:
     /** Number of bits to shift instructions by for predictor addresses. */
     const unsigned instShiftAmt;
diff --git a/src/cpu/pred/indirect.cc b/src/cpu/pred/indirect.cc
new file mode 100644
index 000000000..a8934d55e
--- /dev/null
+++ b/src/cpu/pred/indirect.cc
@@ -0,0 +1,185 @@
+/*
+ * Copyright (c) 2014 ARM Limited
+ * 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: Mitch Hayenga
+ */
+
+#include "cpu/pred/indirect.hh"
+
+#include "base/intmath.hh"
+#include "debug/Indirect.hh"
+
+IndirectPredictor::IndirectPredictor(bool hash_ghr, bool hash_targets,
+    unsigned num_sets, unsigned num_ways,
+    unsigned tag_bits, unsigned path_len, unsigned inst_shift,
+    unsigned num_threads)
+    : hashGHR(hash_ghr), hashTargets(hash_targets),
+      numSets(num_sets), numWays(num_ways), tagBits(tag_bits),
+      pathLength(path_len), instShift(inst_shift)
+{
+    if (!isPowerOf2(numSets)) {
+      panic("Indirect predictor requires power of 2 number of sets");
+    }
+
+    threadInfo.resize(num_threads);
+
+    targetCache.resize(numSets);
+    for (unsigned i = 0; i < numSets; i++) {
+        targetCache[i].resize(numWays);
+    }
+}
+
+bool
+IndirectPredictor::lookup(Addr br_addr, unsigned ghr, TheISA::PCState& target,
+    ThreadID tid)
+{
+    Addr set_index = getSetIndex(br_addr, ghr, tid);
+    Addr tag = getTag(br_addr);
+
+    assert(set_index < numSets);
+
+    DPRINTF(Indirect, "Looking up %x (set:%d)\n", br_addr, set_index);
+    const auto &iset = targetCache[set_index];
+    for (auto way = iset.begin(); way != iset.end(); ++way) {
+        if (way->tag == tag) {
+            DPRINTF(Indirect, "Hit %x (target:%s)\n", br_addr, way->target);
+            target = way->target;
+            return true;
+        }
+    }
+    DPRINTF(Indirect, "Miss %x\n", br_addr);
+    return false;
+}
+
+void
+IndirectPredictor::recordIndirect(Addr br_addr, Addr tgt_addr,
+    InstSeqNum seq_num, ThreadID tid)
+{
+    DPRINTF(Indirect, "Recording %x seq:%d\n", br_addr, seq_num);
+    HistoryEntry entry(br_addr, tgt_addr, seq_num);
+    threadInfo[tid].pathHist.push_back(entry);
+}
+
+void
+IndirectPredictor::commit(InstSeqNum seq_num, ThreadID tid)
+{
+    DPRINTF(Indirect, "Committing seq:%d\n", seq_num);
+    ThreadInfo &t_info = threadInfo[tid];
+
+    if (t_info.pathHist.empty()) return;
+
+    if (t_info.headHistEntry < t_info.pathHist.size() &&
+        t_info.pathHist[t_info.headHistEntry].seqNum <= seq_num) {
+        if (t_info.headHistEntry >= pathLength) {
+            t_info.pathHist.pop_front();
+        } else {
+             ++t_info.headHistEntry;
+        }
+    }
+}
+
+void
+IndirectPredictor::squash(InstSeqNum seq_num, ThreadID tid)
+{
+    DPRINTF(Indirect, "Squashing seq:%d\n", seq_num);
+    ThreadInfo &t_info = threadInfo[tid];
+    auto squash_itr = t_info.pathHist.begin();
+    while (squash_itr != t_info.pathHist.end()) {
+        if (squash_itr->seqNum > seq_num) {
+           break;
+        }
+        ++squash_itr;
+    }
+    if (squash_itr != t_info.pathHist.end()) {
+        DPRINTF(Indirect, "Squashing series starting with sn:%d\n",
+                squash_itr->seqNum);
+    }
+    t_info.pathHist.erase(squash_itr, t_info.pathHist.end());
+}
+
+
+void
+IndirectPredictor::recordTarget(InstSeqNum seq_num, unsigned ghr,
+        const TheISA::PCState& target, ThreadID tid)
+{
+    ThreadInfo &t_info = threadInfo[tid];
+
+    // Should have just squashed so this branch should be the oldest
+    auto hist_entry = *(t_info.pathHist.rbegin());
+    // Temporarily pop it off the history so we can calculate the set
+    t_info.pathHist.pop_back();
+    Addr set_index = getSetIndex(hist_entry.pcAddr, ghr, tid);
+    Addr tag = getTag(hist_entry.pcAddr);
+    hist_entry.targetAddr = target.instAddr();
+    t_info.pathHist.push_back(hist_entry);
+
+    assert(set_index < numSets);
+
+    auto &iset = targetCache[set_index];
+    for (auto way = iset.begin(); way != iset.end(); ++way) {
+        if (way->tag == tag) {
+            DPRINTF(Indirect, "Updating Target (seq: %d br:%x set:%d target:"
+                    "%s)\n", seq_num, hist_entry.pcAddr, set_index, target);
+            way->target = target;
+            return;
+        }
+    }
+
+    DPRINTF(Indirect, "Allocating Target (seq: %d br:%x set:%d target:%s)\n",
+            seq_num, hist_entry.pcAddr, set_index, target);
+    // Did not find entry, random replacement
+    auto &way = iset[rand() % numWays];
+    way.tag = tag;
+    way.target = target;
+}
+
+
+inline Addr
+IndirectPredictor::getSetIndex(Addr br_addr, unsigned ghr, ThreadID tid)
+{
+    ThreadInfo &t_info = threadInfo[tid];
+
+    Addr hash = br_addr >> instShift;
+    if (hashGHR) {
+        hash ^= ghr;
+    }
+    if (hashTargets) {
+        unsigned hash_shift = floorLog2(numSets) / pathLength;
+        for (int i = t_info.pathHist.size()-1, p = 0;
+             i >= 0 && p < pathLength; i--, p++) {
+            hash ^= (t_info.pathHist[i].targetAddr >>
+                     (instShift + p*hash_shift));
+        }
+    }
+    return hash & (numSets-1);
+}
+
+inline Addr
+IndirectPredictor::getTag(Addr br_addr)
+{
+    return (br_addr >> instShift) & ((0x1<<tagBits)-1);
+}
diff --git a/src/cpu/pred/indirect.hh b/src/cpu/pred/indirect.hh
new file mode 100644
index 000000000..89450530e
--- /dev/null
+++ b/src/cpu/pred/indirect.hh
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2014 ARM Limited
+ * 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: Mitch Hayenga
+ */
+
+#ifndef __CPU_PRED_INDIRECT_HH__
+#define __CPU_PRED_INDIRECT_HH__
+
+#include <deque>
+
+#include "arch/isa_traits.hh"
+#include "config/the_isa.hh"
+#include "cpu/inst_seq.hh"
+
+class IndirectPredictor
+{
+  public:
+    IndirectPredictor(bool hash_ghr, bool hash_targets,
+                      unsigned num_sets, unsigned num_ways,
+                      unsigned tag_bits, unsigned path_len,
+                      unsigned inst_shift, unsigned num_threads);
+    bool lookup(Addr br_addr, unsigned ghr, TheISA::PCState& br_target,
+                ThreadID tid);
+    void recordIndirect(Addr br_addr, Addr tgt_addr, InstSeqNum seq_num,
+                        ThreadID tid);
+    void commit(InstSeqNum seq_num, ThreadID tid);
+    void squash(InstSeqNum seq_num, ThreadID tid);
+    void recordTarget(InstSeqNum seq_num, unsigned ghr,
+                      const TheISA::PCState& target, ThreadID tid);
+
+  private:
+    const bool hashGHR;
+    const bool hashTargets;
+    const unsigned numSets;
+    const unsigned numWays;
+    const unsigned tagBits;
+    const unsigned pathLength;
+    const unsigned instShift;
+
+    struct IPredEntry
+    {
+        IPredEntry() : tag(0), target(0) { }
+        Addr tag;
+        TheISA::PCState target;
+    };
+
+    std::vector<std::vector<IPredEntry> > targetCache;
+
+    Addr getSetIndex(Addr br_addr, unsigned ghr, ThreadID tid);
+    Addr getTag(Addr br_addr);
+
+    struct HistoryEntry
+    {
+        HistoryEntry(Addr br_addr, Addr tgt_addr, InstSeqNum seq_num)
+            : pcAddr(br_addr), targetAddr(tgt_addr), seqNum(seq_num) { }
+        Addr pcAddr;
+        Addr targetAddr;
+        InstSeqNum seqNum;
+    };
+
+
+    struct ThreadInfo {
+        ThreadInfo() : headHistEntry(0) { }
+
+        std::deque<HistoryEntry> pathHist;
+        unsigned headHistEntry;
+    };
+
+    std::vector<ThreadInfo> threadInfo;
+};
+
+#endif // __CPU_PRED_INDIRECT_HH__
diff --git a/src/cpu/pred/tournament.cc b/src/cpu/pred/tournament.cc
index ea6be46fa..2dd48a09c 100644
--- a/src/cpu/pred/tournament.cc
+++ b/src/cpu/pred/tournament.cc
@@ -388,6 +388,12 @@ TournamentBPParams::create()
     return new TournamentBP(this);
 }
 
+unsigned
+TournamentBP::getGHR(void *bp_history) const
+{
+    return static_cast<BPHistory *>(bp_history)->globalHistory;
+}
+
 #ifdef DEBUG
 int
 TournamentBP::BPHistory::newCount = 0;
diff --git a/src/cpu/pred/tournament.hh b/src/cpu/pred/tournament.hh
index 8fb5b515c..82a1daa64 100644
--- a/src/cpu/pred/tournament.hh
+++ b/src/cpu/pred/tournament.hh
@@ -114,6 +114,8 @@ class TournamentBP : public BPredUnit
      */
     void squash(void *bp_history);
 
+    unsigned getGHR(void *bp_history) const;
+
     /** Returns the global history. */
     inline unsigned readGlobalHist() { return globalHistory; }