arch,cpu: Add vector predicate registers

Latest-gen. vector/SIMD extensions, including the Arm Scalable Vector
Extension (SVE), introduce the notion of a predicate register file.
This changeset adds this feature across architectures and CPU models.

Change-Id: Iebcadbad89c0a582ff8b1b70de353305db603946
Signed-off-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/13715
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

15 files changed, 303 insertions, 13 deletions

diff --git a/src/cpu/o3/O3CPU.py b/src/cpu/o3/O3CPU.py
index 32cc19010..e73c09334 100644
--- a/src/cpu/o3/O3CPU.py
+++ b/src/cpu/o3/O3CPU.py
@@ -150,6 +150,8 @@ class DerivO3CPU(BaseCPU):
         _defaultNumPhysCCRegs = Self.numPhysIntRegs * 5
     numPhysVecRegs = Param.Unsigned(256, "Number of physical vector "
                                       "registers")
+    numPhysVecPredRegs = Param.Unsigned(32, "Number of physical predicate "
+                                      "registers")
     numPhysCCRegs = Param.Unsigned(_defaultNumPhysCCRegs,
                                    "Number of physical cc registers")
     numIQEntries = Param.Unsigned(64, "Number of instruction queue entries")
diff --git a/src/cpu/o3/comm.hh b/src/cpu/o3/comm.hh
index f5be5a804..df518b1e4 100644
--- a/src/cpu/o3/comm.hh
+++ b/src/cpu/o3/comm.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2016 ARM Limited
+ * Copyright (c) 2011, 2016-2017 ARM Limited
  * Copyright (c) 2013 Advanced Micro Devices, Inc.
  * All rights reserved
  *
@@ -121,6 +121,9 @@ class PhysRegId : private RegId {
     /** @Return true if it is a vector element physical register. */
     bool isVectorPhysElem() const { return isVecElem(); }
 
+    /** @return true if it is a vector predicate physical register. */
+    bool isVecPredPhysReg() const { return isVecPredReg(); }
+
     /** @Return true if it is a  condition-code physical register. */
     bool isMiscPhysReg() const { return isMiscReg(); }
 
diff --git a/src/cpu/o3/cpu.cc b/src/cpu/o3/cpu.cc
index 5d92d92dc..ef3b17202 100644
--- a/src/cpu/o3/cpu.cc
+++ b/src/cpu/o3/cpu.cc
@@ -159,6 +159,7 @@ FullO3CPU<Impl>::FullO3CPU(DerivO3CPUParams *params)
       regFile(params->numPhysIntRegs,
               params->numPhysFloatRegs,
               params->numPhysVecRegs,
+              params->numPhysVecPredRegs,
               params->numPhysCCRegs,
               vecMode),
 
@@ -258,6 +259,7 @@ FullO3CPU<Impl>::FullO3CPU(DerivO3CPUParams *params)
     assert(params->numPhysIntRegs   >= numThreads * TheISA::NumIntRegs);
     assert(params->numPhysFloatRegs >= numThreads * TheISA::NumFloatRegs);
     assert(params->numPhysVecRegs >= numThreads * TheISA::NumVecRegs);
+    assert(params->numPhysVecPredRegs >= numThreads * TheISA::NumVecPredRegs);
     assert(params->numPhysCCRegs >= numThreads * TheISA::NumCCRegs);
 
     rename.setScoreboard(&scoreboard);
@@ -325,6 +327,13 @@ FullO3CPU<Impl>::FullO3CPU(DerivO3CPUParams *params)
             }
         }
 
+        for (RegIndex ridx = 0; ridx < TheISA::NumVecPredRegs; ++ridx) {
+            PhysRegIdPtr phys_reg = freeList.getVecPredReg();
+            renameMap[tid].setEntry(RegId(VecPredRegClass, ridx), phys_reg);
+            commitRenameMap[tid].setEntry(
+                    RegId(VecPredRegClass, ridx), phys_reg);
+        }
+
         for (RegIndex ridx = 0; ridx < TheISA::NumCCRegs; ++ridx) {
             PhysRegIdPtr phys_reg = freeList.getCCReg();
             renameMap[tid].setEntry(RegId(CCRegClass, ridx), phys_reg);
@@ -538,6 +547,16 @@ FullO3CPU<Impl>::regStats()
         .desc("number of vector regfile writes")
         .prereq(vecRegfileWrites);
 
+    vecPredRegfileReads
+        .name(name() + ".pred_regfile_reads")
+        .desc("number of predicate regfile reads")
+        .prereq(vecPredRegfileReads);
+
+    vecPredRegfileWrites
+        .name(name() + ".pred_regfile_writes")
+        .desc("number of predicate regfile writes")
+        .prereq(vecPredRegfileWrites);
+
     ccRegfileReads
         .name(name() + ".cc_regfile_reads")
         .desc("number of cc regfile reads")
@@ -883,6 +902,14 @@ FullO3CPU<Impl>::removeThread(ThreadID tid)
         freeList.addReg(phys_reg);
     }
 
+    // Unbind Float Regs from Rename Map
+    for (unsigned preg = 0; preg < TheISA::NumVecPredRegs; preg++) {
+        PhysRegIdPtr phys_reg = renameMap[tid].lookup(
+            RegId(VecPredRegClass, preg));
+        scoreboard.unsetReg(phys_reg);
+        freeList.addReg(phys_reg);
+    }
+
     // Unbind condition-code Regs from Rename Map
     for (RegId reg_id(CCRegClass, 0); reg_id.index() < TheISA::NumCCRegs;
          reg_id.index()++) {
@@ -1334,6 +1361,24 @@ FullO3CPU<Impl>::readVecElem(PhysRegIdPtr phys_reg) const -> const VecElem&
 }
 
 template <class Impl>
+auto
+FullO3CPU<Impl>::readVecPredReg(PhysRegIdPtr phys_reg) const
+        -> const VecPredRegContainer&
+{
+    vecPredRegfileReads++;
+    return regFile.readVecPredReg(phys_reg);
+}
+
+template <class Impl>
+auto
+FullO3CPU<Impl>::getWritableVecPredReg(PhysRegIdPtr phys_reg)
+        -> VecPredRegContainer&
+{
+    vecPredRegfileWrites++;
+    return regFile.getWritableVecPredReg(phys_reg);
+}
+
+template <class Impl>
 CCReg
 FullO3CPU<Impl>::readCCReg(PhysRegIdPtr phys_reg)
 {
@@ -1375,6 +1420,15 @@ FullO3CPU<Impl>::setVecElem(PhysRegIdPtr phys_reg, const VecElem& val)
 
 template <class Impl>
 void
+FullO3CPU<Impl>::setVecPredReg(PhysRegIdPtr phys_reg,
+                               const VecPredRegContainer& val)
+{
+    vecPredRegfileWrites++;
+    regFile.setVecPredReg(phys_reg, val);
+}
+
+template <class Impl>
+void
 FullO3CPU<Impl>::setCCReg(PhysRegIdPtr phys_reg, CCReg val)
 {
     ccRegfileWrites++;
@@ -1434,6 +1488,26 @@ FullO3CPU<Impl>::readArchVecElem(const RegIndex& reg_idx, const ElemIndex& ldx,
 }
 
 template <class Impl>
+auto
+FullO3CPU<Impl>::readArchVecPredReg(int reg_idx, ThreadID tid) const
+        -> const VecPredRegContainer&
+{
+    PhysRegIdPtr phys_reg = commitRenameMap[tid].lookup(
+                RegId(VecPredRegClass, reg_idx));
+    return readVecPredReg(phys_reg);
+}
+
+template <class Impl>
+auto
+FullO3CPU<Impl>::getWritableArchVecPredReg(int reg_idx, ThreadID tid)
+        -> VecPredRegContainer&
+{
+    PhysRegIdPtr phys_reg = commitRenameMap[tid].lookup(
+                RegId(VecPredRegClass, reg_idx));
+    return getWritableVecPredReg(phys_reg);
+}
+
+template <class Impl>
 CCReg
 FullO3CPU<Impl>::readArchCCReg(int reg_idx, ThreadID tid)
 {
@@ -1488,6 +1562,16 @@ FullO3CPU<Impl>::setArchVecElem(const RegIndex& reg_idx, const ElemIndex& ldx,
 
 template <class Impl>
 void
+FullO3CPU<Impl>::setArchVecPredReg(int reg_idx, const VecPredRegContainer& val,
+                                   ThreadID tid)
+{
+    PhysRegIdPtr phys_reg = commitRenameMap[tid].lookup(
+                RegId(VecPredRegClass, reg_idx));
+    setVecPredReg(phys_reg, val);
+}
+
+template <class Impl>
+void
 FullO3CPU<Impl>::setArchCCReg(int reg_idx, CCReg val, ThreadID tid)
 {
     ccRegfileWrites++;
diff --git a/src/cpu/o3/cpu.hh b/src/cpu/o3/cpu.hh
index b5f754056..30ed4ef3b 100644
--- a/src/cpu/o3/cpu.hh
+++ b/src/cpu/o3/cpu.hh
@@ -107,6 +107,8 @@ class FullO3CPU : public BaseO3CPU
     using VecElem =  TheISA::VecElem;
     using VecRegContainer =  TheISA::VecRegContainer;
 
+    using VecPredRegContainer = TheISA::VecPredRegContainer;
+
     typedef O3ThreadState<Impl> ImplState;
     typedef O3ThreadState<Impl> Thread;
 
@@ -457,6 +459,10 @@ class FullO3CPU : public BaseO3CPU
 
     const VecElem& readVecElem(PhysRegIdPtr reg_idx) const;
 
+    const VecPredRegContainer& readVecPredReg(PhysRegIdPtr reg_idx) const;
+
+    VecPredRegContainer& getWritableVecPredReg(PhysRegIdPtr reg_idx);
+
     TheISA::CCReg readCCReg(PhysRegIdPtr phys_reg);
 
     void setIntReg(PhysRegIdPtr phys_reg, RegVal val);
@@ -467,6 +473,8 @@ class FullO3CPU : public BaseO3CPU
 
     void setVecElem(PhysRegIdPtr reg_idx, const VecElem& val);
 
+    void setVecPredReg(PhysRegIdPtr reg_idx, const VecPredRegContainer& val);
+
     void setCCReg(PhysRegIdPtr phys_reg, TheISA::CCReg val);
 
     RegVal readArchIntReg(int reg_idx, ThreadID tid);
@@ -501,6 +509,11 @@ class FullO3CPU : public BaseO3CPU
     const VecElem& readArchVecElem(const RegIndex& reg_idx,
                                    const ElemIndex& ldx, ThreadID tid) const;
 
+    const VecPredRegContainer& readArchVecPredReg(int reg_idx,
+                                                  ThreadID tid) const;
+
+    VecPredRegContainer& getWritableArchVecPredReg(int reg_idx, ThreadID tid);
+
     TheISA::CCReg readArchCCReg(int reg_idx, ThreadID tid);
 
     /** Architectural register accessors.  Looks up in the commit
@@ -512,6 +525,9 @@ class FullO3CPU : public BaseO3CPU
 
     void setArchFloatRegBits(int reg_idx, RegVal val, ThreadID tid);
 
+    void setArchVecPredReg(int reg_idx, const VecPredRegContainer& val,
+                           ThreadID tid);
+
     void setArchVecReg(int reg_idx, const VecRegContainer& val, ThreadID tid);
 
     void setArchVecElem(const RegIndex& reg_idx, const ElemIndex& ldx,
@@ -805,6 +821,9 @@ class FullO3CPU : public BaseO3CPU
     //number of vector register file accesses
     mutable Stats::Scalar vecRegfileReads;
     Stats::Scalar vecRegfileWrites;
+    //number of predicate register file accesses
+    mutable Stats::Scalar vecPredRegfileReads;
+    Stats::Scalar vecPredRegfileWrites;
     //number of CC register file accesses
     Stats::Scalar ccRegfileReads;
     Stats::Scalar ccRegfileWrites;
diff --git a/src/cpu/o3/dyn_inst.hh b/src/cpu/o3/dyn_inst.hh
index 5bd0f8e47..9793f4ead 100644
--- a/src/cpu/o3/dyn_inst.hh
+++ b/src/cpu/o3/dyn_inst.hh
@@ -70,6 +70,7 @@ class BaseO3DynInst : public BaseDynInst<Impl>
     using VecRegContainer = TheISA::VecRegContainer;
     using VecElem = TheISA::VecElem;
     static constexpr auto NumVecElemPerVecReg = TheISA::NumVecElemPerVecReg;
+    using VecPredRegContainer = TheISA::VecPredRegContainer;
 
     enum {
         MaxInstSrcRegs = TheISA::MaxInstSrcRegs,        //< Max source regs
@@ -231,6 +232,10 @@ class BaseO3DynInst : public BaseDynInst<Impl>
                 this->setVecElemOperand(this->staticInst.get(), idx,
                                this->cpu->readVecElem(prev_phys_reg));
                 break;
+              case VecPredRegClass:
+                this->setVecPredRegOperand(this->staticInst.get(), idx,
+                               this->cpu->readVecPredReg(prev_phys_reg));
+                break;
               case CCRegClass:
                 this->setCCRegOperand(this->staticInst.get(), idx,
                                this->cpu->readCCReg(prev_phys_reg));
@@ -361,6 +366,18 @@ class BaseO3DynInst : public BaseDynInst<Impl>
         return this->cpu->readVecElem(this->_srcRegIdx[idx]);
     }
 
+    const VecPredRegContainer&
+    readVecPredRegOperand(const StaticInst *si, int idx) const override
+    {
+        return this->cpu->readVecPredReg(this->_srcRegIdx[idx]);
+    }
+
+    VecPredRegContainer&
+    getWritableVecPredRegOperand(const StaticInst *si, int idx) override
+    {
+        return this->cpu->getWritableVecPredReg(this->_destRegIdx[idx]);
+    }
+
     CCReg readCCRegOperand(const StaticInst *si, int idx)
     {
         return this->cpu->readCCReg(this->_srcRegIdx[idx]);
@@ -399,6 +416,14 @@ class BaseO3DynInst : public BaseDynInst<Impl>
         BaseDynInst<Impl>::setVecElemOperand(si, idx, val);
     }
 
+    void
+    setVecPredRegOperand(const StaticInst *si, int idx,
+                         const VecPredRegContainer& val) override
+    {
+        this->cpu->setVecPredReg(this->_destRegIdx[idx], val);
+        BaseDynInst<Impl>::setVecPredRegOperand(si, idx, val);
+    }
+
     void setCCRegOperand(const StaticInst *si, int idx, CCReg val)
     {
         this->cpu->setCCReg(this->_destRegIdx[idx], val);
diff --git a/src/cpu/o3/free_list.hh b/src/cpu/o3/free_list.hh
index e7a899cdf..46bebf30d 100644
--- a/src/cpu/o3/free_list.hh
+++ b/src/cpu/o3/free_list.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016 ARM Limited
+ * Copyright (c) 2016-2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -138,6 +138,9 @@ class UnifiedFreeList
     SimpleFreeList vecElemList;
     /** @} */
 
+    /** The list of free predicate registers. */
+    SimpleFreeList predList;
+
     /** The list of free condition-code registers. */
     SimpleFreeList ccList;
 
@@ -183,6 +186,9 @@ class UnifiedFreeList
     /** Gets a free vector elemenet register. */
     PhysRegIdPtr getVecElem() { return vecElemList.getReg(); }
 
+    /** Gets a free predicate register. */
+    PhysRegIdPtr getVecPredReg() { return predList.getReg(); }
+
     /** Gets a free cc register. */
     PhysRegIdPtr getCCReg() { return ccList.getReg(); }
 
@@ -207,6 +213,9 @@ class UnifiedFreeList
         vecElemList.addReg(freed_reg);
     }
 
+    /** Adds a predicate register back to the free list. */
+    void addVecPredReg(PhysRegIdPtr freed_reg) { predList.addReg(freed_reg); }
+
     /** Adds a cc register back to the free list. */
     void addCCReg(PhysRegIdPtr freed_reg) { ccList.addReg(freed_reg); }
 
@@ -222,6 +231,9 @@ class UnifiedFreeList
     /** Checks if there are any free vector registers. */
     bool hasFreeVecElems() const { return vecElemList.hasFreeRegs(); }
 
+    /** Checks if there are any free predicate registers. */
+    bool hasFreeVecPredRegs() const { return predList.hasFreeRegs(); }
+
     /** Checks if there are any free cc registers. */
     bool hasFreeCCRegs() const { return ccList.hasFreeRegs(); }
 
@@ -237,6 +249,9 @@ class UnifiedFreeList
     /** Returns the number of free vector registers. */
     unsigned numFreeVecElems() const { return vecElemList.numFreeRegs(); }
 
+    /** Returns the number of free predicate registers. */
+    unsigned numFreeVecPredRegs() const { return predList.numFreeRegs(); }
+
     /** Returns the number of free cc registers. */
     unsigned numFreeCCRegs() const { return ccList.numFreeRegs(); }
 };
@@ -267,6 +282,9 @@ UnifiedFreeList::addRegs(InputIt first, InputIt last)
         case VecElemClass:
             vecElemList.addRegs(first, last);
             break;
+        case VecPredRegClass:
+            predList.addRegs(first, last);
+            break;
         case CCRegClass:
             ccList.addRegs(first, last);
             break;
@@ -297,6 +315,9 @@ UnifiedFreeList::addReg(PhysRegIdPtr freed_reg)
         case VecElemClass:
             vecElemList.addReg(freed_reg);
             break;
+        case VecPredRegClass:
+            predList.addReg(freed_reg);
+            break;
         case CCRegClass:
             ccList.addReg(freed_reg);
             break;
diff --git a/src/cpu/o3/inst_queue_impl.hh b/src/cpu/o3/inst_queue_impl.hh
index 4a55a91ea..ddd7b6d5f 100644
--- a/src/cpu/o3/inst_queue_impl.hh
+++ b/src/cpu/o3/inst_queue_impl.hh
@@ -104,6 +104,7 @@ InstructionQueue<Impl>::InstructionQueue(O3CPU *cpu_ptr, IEW *iew_ptr,
     numPhysRegs = params->numPhysIntRegs + params->numPhysFloatRegs +
                     params->numPhysVecRegs +
                     params->numPhysVecRegs * TheISA::NumVecElemPerVecReg +
+                    params->numPhysVecPredRegs +
                     params->numPhysCCRegs;
 
     //Create an entry for each physical register within the
diff --git a/src/cpu/o3/regfile.cc b/src/cpu/o3/regfile.cc
index 2f41e2ac2..cc4bba6b0 100644
--- a/src/cpu/o3/regfile.cc
+++ b/src/cpu/o3/regfile.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016 ARM Limited
+ * Copyright (c) 2016-2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -52,22 +52,26 @@
 PhysRegFile::PhysRegFile(unsigned _numPhysicalIntRegs,
                          unsigned _numPhysicalFloatRegs,
                          unsigned _numPhysicalVecRegs,
+                         unsigned _numPhysicalVecPredRegs,
                          unsigned _numPhysicalCCRegs,
                          VecMode vmode)
     : intRegFile(_numPhysicalIntRegs),
       floatRegFile(_numPhysicalFloatRegs),
       vectorRegFile(_numPhysicalVecRegs),
+      vecPredRegFile(_numPhysicalVecPredRegs),
       ccRegFile(_numPhysicalCCRegs),
       numPhysicalIntRegs(_numPhysicalIntRegs),
       numPhysicalFloatRegs(_numPhysicalFloatRegs),
       numPhysicalVecRegs(_numPhysicalVecRegs),
       numPhysicalVecElemRegs(_numPhysicalVecRegs *
                              NumVecElemPerVecReg),
+      numPhysicalVecPredRegs(_numPhysicalVecPredRegs),
       numPhysicalCCRegs(_numPhysicalCCRegs),
       totalNumRegs(_numPhysicalIntRegs
                    + _numPhysicalFloatRegs
                    + _numPhysicalVecRegs
                    + _numPhysicalVecRegs * NumVecElemPerVecReg
+                   + _numPhysicalVecPredRegs
                    + _numPhysicalCCRegs),
       vecMode(vmode)
 {
@@ -108,6 +112,12 @@ PhysRegFile::PhysRegFile(unsigned _numPhysicalIntRegs,
         }
     }
 
+    // The next batch of the registers are the predicate physical
+    // registers; put them onto the predicate free list.
+    for (phys_reg = 0; phys_reg < numPhysicalVecPredRegs; phys_reg++) {
+        vecPredRegIds.emplace_back(VecPredRegClass, phys_reg, flat_reg_idx++);
+    }
+
     // The rest of the registers are the condition-code physical
     // registers; put them onto the condition-code free list.
     for (phys_reg = 0; phys_reg < numPhysicalCCRegs; phys_reg++) {
@@ -159,6 +169,13 @@ PhysRegFile::initFreeList(UnifiedFreeList *freeList)
     else
         freeList->addRegs(vecElemIds.begin(), vecElemIds.end());
 
+    // The next batch of the registers are the predicate physical
+    // registers; put them onto the predicate free list.
+    for (reg_idx = 0; reg_idx < numPhysicalVecPredRegs; reg_idx++) {
+        assert(vecPredRegIds[reg_idx].index() == reg_idx);
+    }
+    freeList->addRegs(vecPredRegIds.begin(), vecPredRegIds.end());
+
     // The rest of the registers are the condition-code physical
     // registers; put them onto the condition-code free list.
     for (reg_idx = 0; reg_idx < numPhysicalCCRegs; reg_idx++) {
@@ -191,6 +208,8 @@ PhysRegFile::getRegIds(RegClass cls) -> IdRange
         return std::make_pair(vecRegIds.begin(), vecRegIds.end());
       case VecElemClass:
         return std::make_pair(vecElemIds.begin(), vecElemIds.end());
+      case VecPredRegClass:
+        return std::make_pair(vecPredRegIds.begin(), vecPredRegIds.end());
       case CCRegClass:
         return std::make_pair(ccRegIds.begin(), ccRegIds.end());
       case MiscRegClass:
diff --git a/src/cpu/o3/regfile.hh b/src/cpu/o3/regfile.hh
index 9d9113240..4077c99a4 100644
--- a/src/cpu/o3/regfile.hh
+++ b/src/cpu/o3/regfile.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016 ARM Limited
+ * Copyright (c) 2016-2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -70,6 +70,7 @@ class PhysRegFile
     using VecRegContainer = TheISA::VecRegContainer;
     using PhysIds = std::vector<PhysRegId>;
     using VecMode = Enums::VecRegRenameMode;
+    using VecPredRegContainer = TheISA::VecPredRegContainer;
   public:
     using IdRange = std::pair<PhysIds::const_iterator,
                               PhysIds::const_iterator>;
@@ -89,6 +90,10 @@ class PhysRegFile
     std::vector<PhysRegId> vecRegIds;
     std::vector<PhysRegId> vecElemIds;
 
+    /** Predicate register file. */
+    std::vector<VecPredRegContainer> vecPredRegFile;
+    std::vector<PhysRegId> vecPredRegIds;
+
     /** Condition-code register file. */
     std::vector<CCReg> ccRegFile;
     std::vector<PhysRegId> ccRegIds;
@@ -117,6 +122,11 @@ class PhysRegFile
     unsigned numPhysicalVecElemRegs;
 
     /**
+     * Number of physical predicate registers
+     */
+    unsigned numPhysicalVecPredRegs;
+
+    /**
      * Number of physical CC registers
      */
     unsigned numPhysicalCCRegs;
@@ -135,6 +145,7 @@ class PhysRegFile
     PhysRegFile(unsigned _numPhysicalIntRegs,
                 unsigned _numPhysicalFloatRegs,
                 unsigned _numPhysicalVecRegs,
+                unsigned _numPhysicalVecPredRegs,
                 unsigned _numPhysicalCCRegs,
                 VecMode vmode
                 );
@@ -154,6 +165,8 @@ class PhysRegFile
     unsigned numFloatPhysRegs() const { return numPhysicalFloatRegs; }
     /** @return the number of vector physical registers. */
     unsigned numVecPhysRegs() const { return numPhysicalVecRegs; }
+    /** @return the number of predicate physical registers. */
+    unsigned numPredPhysRegs() const { return numPhysicalVecPredRegs; }
 
     /** @return the number of vector physical registers. */
     unsigned numVecElemPhysRegs() const { return numPhysicalVecElemRegs; }
@@ -201,7 +214,7 @@ class PhysRegFile
 
         DPRINTF(IEW, "RegFile: Access to vector register %i, has "
                 "data %s\n", int(phys_reg->index()),
-                vectorRegFile[phys_reg->index()].as<VecElem>().print());
+                vectorRegFile[phys_reg->index()].print());
 
         return vectorRegFile[phys_reg->index()];
     }
@@ -258,6 +271,24 @@ class PhysRegFile
         return val;
     }
 
+    /** Reads a predicate register. */
+    const VecPredRegContainer& readVecPredReg(PhysRegIdPtr phys_reg) const
+    {
+        assert(phys_reg->isVecPredPhysReg());
+
+        DPRINTF(IEW, "RegFile: Access to predicate register %i, has "
+                "data %s\n", int(phys_reg->index()),
+                vecPredRegFile[phys_reg->index()].print());
+
+        return vecPredRegFile[phys_reg->index()];
+    }
+
+    VecPredRegContainer& getWritableVecPredReg(PhysRegIdPtr phys_reg)
+    {
+        /* const_cast for not duplicating code above. */
+        return const_cast<VecPredRegContainer&>(readVecPredReg(phys_reg));
+    }
+
     /** Reads a condition-code register. */
     CCReg
     readCCReg(PhysRegIdPtr phys_reg)
@@ -321,6 +352,17 @@ class PhysRegFile
                 val;
     }
 
+    /** Sets a predicate register to the given value. */
+    void setVecPredReg(PhysRegIdPtr phys_reg, const VecPredRegContainer& val)
+    {
+        assert(phys_reg->isVecPredPhysReg());
+
+        DPRINTF(IEW, "RegFile: Setting predicate register %i to %s\n",
+                int(phys_reg->index()), val.print());
+
+        vecPredRegFile[phys_reg->index()] = val;
+    }
+
     /** Sets a condition-code register to the given value. */
     void
     setCCReg(PhysRegIdPtr phys_reg, CCReg val)
diff --git a/src/cpu/o3/rename.hh b/src/cpu/o3/rename.hh
index bd5e72dec..a091c0908 100644
--- a/src/cpu/o3/rename.hh
+++ b/src/cpu/o3/rename.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012 ARM Limited
+ * Copyright (c) 2012, 2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -514,6 +514,7 @@ class DefaultRename
     Stats::Scalar intRenameLookups;
     Stats::Scalar fpRenameLookups;
     Stats::Scalar vecRenameLookups;
+    Stats::Scalar vecPredRenameLookups;
     /** Stat for total number of committed renaming mappings. */
     Stats::Scalar renameCommittedMaps;
     /** Stat for total number of mappings that were undone due to a squash. */
diff --git a/src/cpu/o3/rename_impl.hh b/src/cpu/o3/rename_impl.hh
index ed5dfb6eb..b63163f04 100644
--- a/src/cpu/o3/rename_impl.hh
+++ b/src/cpu/o3/rename_impl.hh
@@ -196,6 +196,10 @@ DefaultRename<Impl>::regStats()
         .name(name() + ".vec_rename_lookups")
         .desc("Number of vector rename lookups")
         .prereq(vecRenameLookups);
+    vecPredRenameLookups
+        .name(name() + ".vec_pred_rename_lookups")
+        .desc("Number of vector predicate rename lookups")
+        .prereq(vecPredRenameLookups);
 }
 
 template <class Impl>
@@ -659,6 +663,7 @@ DefaultRename<Impl>::renameInsts(ThreadID tid)
                                        inst->numFPDestRegs(),
                                        inst->numVecDestRegs(),
                                        inst->numVecElemDestRegs(),
+                                       inst->numVecPredDestRegs(),
                                        inst->numCCDestRegs())) {
             DPRINTF(Rename, "Blocking due to lack of free "
                     "physical registers to rename to.\n");
@@ -1041,6 +1046,9 @@ DefaultRename<Impl>::renameSrcRegs(const DynInstPtr &inst, ThreadID tid)
           case VecElemClass:
             vecRenameLookups++;
             break;
+          case VecPredRegClass:
+            vecPredRenameLookups++;
+            break;
           case CCRegClass:
           case MiscRegClass:
             break;
@@ -1256,7 +1264,7 @@ DefaultRename<Impl>::readFreeEntries(ThreadID tid)
     }
 
     DPRINTF(Rename, "[tid:%i]: Free IQ: %i, Free ROB: %i, "
-                    "Free LQ: %i, Free SQ: %i, FreeRM %i(%i %i %i %i)\n",
+                    "Free LQ: %i, Free SQ: %i, FreeRM %i(%i %i %i %i %i)\n",
             tid,
             freeEntries[tid].iqEntries,
             freeEntries[tid].robEntries,
@@ -1266,6 +1274,7 @@ DefaultRename<Impl>::readFreeEntries(ThreadID tid)
             renameMap[tid]->numFreeIntEntries(),
             renameMap[tid]->numFreeFloatEntries(),
             renameMap[tid]->numFreeVecEntries(),
+            renameMap[tid]->numFreePredEntries(),
             renameMap[tid]->numFreeCCEntries());
 
     DPRINTF(Rename, "[tid:%i]: %i instructions not yet in ROB\n",
diff --git a/src/cpu/o3/rename_map.cc b/src/cpu/o3/rename_map.cc
index 86c43932c..603f1ff36 100644
--- a/src/cpu/o3/rename_map.cc
+++ b/src/cpu/o3/rename_map.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016,2019 ARM Limited
+ * Copyright (c) 2016-2017,2019 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -120,6 +120,8 @@ UnifiedRenameMap::init(PhysRegFile *_regFile,
     vecElemMap.init(TheISA::NumVecRegs * NVecElems,
             &(freeList->vecElemList), (RegIndex)-1);
 
+    predMap.init(TheISA::NumVecPredRegs, &(freeList->predList), (RegIndex)-1);
+
     ccMap.init(TheISA::NumCCRegs, &(freeList->ccList), (RegIndex)-1);
 
 }
diff --git a/src/cpu/o3/rename_map.hh b/src/cpu/o3/rename_map.hh
index d30668027..5424633e5 100644
--- a/src/cpu/o3/rename_map.hh
+++ b/src/cpu/o3/rename_map.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016 ARM Limited
+ * Copyright (c) 2015-2017 ARM Limited
  * All rights reserved.
  *
  * The license below extends only to copyright in the software and shall
@@ -172,6 +172,7 @@ class UnifiedRenameMap
   private:
     static constexpr uint32_t NVecElems = TheISA::NumVecElemPerVecReg;
     using VecReg = TheISA::VecReg;
+    using VecPredReg = TheISA::VecPredReg;
 
     /** The integer register rename map */
     SimpleRenameMap intMap;
@@ -188,6 +189,9 @@ class UnifiedRenameMap
     /** The vector element register rename map */
     SimpleRenameMap vecElemMap;
 
+    /** The predicate register rename map */
+    SimpleRenameMap predMap;
+
     using VecMode = Enums::VecRegRenameMode;
     VecMode vecMode;
 
@@ -235,6 +239,8 @@ class UnifiedRenameMap
           case VecElemClass:
             assert(vecMode == Enums::Elem);
             return vecElemMap.rename(arch_reg);
+          case VecPredRegClass:
+            return predMap.rename(arch_reg);
           case CCRegClass:
             return ccMap.rename(arch_reg);
           case MiscRegClass:
@@ -276,6 +282,9 @@ class UnifiedRenameMap
             assert(vecMode == Enums::Elem);
             return  vecElemMap.lookup(arch_reg);
 
+          case VecPredRegClass:
+            return predMap.lookup(arch_reg);
+
           case CCRegClass:
             return ccMap.lookup(arch_reg);
 
@@ -319,6 +328,10 @@ class UnifiedRenameMap
             assert(vecMode == Enums::Elem);
             return vecElemMap.setEntry(arch_reg, phys_reg);
 
+          case VecPredRegClass:
+            assert(phys_reg->isVecPredPhysReg());
+            return predMap.setEntry(arch_reg, phys_reg);
+
           case CCRegClass:
             assert(phys_reg->isCCPhysReg());
             return ccMap.setEntry(arch_reg, phys_reg);
@@ -345,10 +358,11 @@ class UnifiedRenameMap
      */
     unsigned numFreeEntries() const
     {
-        return std::min(
+        return std::min(std::min(
                 std::min(intMap.numFreeEntries(), floatMap.numFreeEntries()),
                 vecMode == Enums::Full ? vecMap.numFreeEntries()
-                                    : vecElemMap.numFreeEntries());
+                                    : vecElemMap.numFreeEntries()),
+                predMap.numFreeEntries());
     }
 
     unsigned numFreeIntEntries() const { return intMap.numFreeEntries(); }
@@ -359,18 +373,21 @@ class UnifiedRenameMap
                 ? vecMap.numFreeEntries()
                 : vecElemMap.numFreeEntries();
     }
+    unsigned numFreePredEntries() const { return predMap.numFreeEntries(); }
     unsigned numFreeCCEntries() const { return ccMap.numFreeEntries(); }
 
     /**
      * Return whether there are enough registers to serve the request.
      */
     bool canRename(uint32_t intRegs, uint32_t floatRegs, uint32_t vectorRegs,
-                    uint32_t vecElemRegs, uint32_t ccRegs) const
+                   uint32_t vecElemRegs, uint32_t vecPredRegs,
+                   uint32_t ccRegs) const
     {
         return intRegs <= intMap.numFreeEntries() &&
             floatRegs <= floatMap.numFreeEntries() &&
             vectorRegs <= vecMap.numFreeEntries() &&
             vecElemRegs <= vecElemMap.numFreeEntries() &&
+            vecPredRegs <= predMap.numFreeEntries() &&
             ccRegs <= ccMap.numFreeEntries();
     }
     /**
diff --git a/src/cpu/o3/thread_context.hh b/src/cpu/o3/thread_context.hh
index c74936469..7858f5a0a 100644
--- a/src/cpu/o3/thread_context.hh
+++ b/src/cpu/o3/thread_context.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011-2012, 2016 ARM Limited
+ * Copyright (c) 2011-2012, 2016-2018 ARM Limited
  * Copyright (c) 2013 Advanced Micro Devices, Inc.
  * All rights reserved
  *
@@ -263,6 +263,14 @@ class O3ThreadContext : public ThreadContext
         return readVecElemFlat(flattenRegId(reg).index(), reg.elemIndex());
     }
 
+    virtual const VecPredRegContainer& readVecPredReg(const RegId& id) const {
+        return readVecPredRegFlat(flattenRegId(id).index());
+    }
+
+    virtual VecPredRegContainer& getWritableVecPredReg(const RegId& id) {
+        return getWritableVecPredRegFlat(flattenRegId(id).index());
+    }
+
     virtual CCReg readCCReg(int reg_idx) {
         return readCCRegFlat(flattenRegId(RegId(CCRegClass,
                                                  reg_idx)).index());
@@ -295,6 +303,13 @@ class O3ThreadContext : public ThreadContext
     }
 
     virtual void
+    setVecPredReg(const RegId& reg,
+                  const VecPredRegContainer& val)
+    {
+        setVecPredRegFlat(flattenRegId(reg).index(), val);
+    }
+
+    virtual void
     setCCReg(int reg_idx, CCReg val)
     {
         setCCRegFlat(flattenRegId(RegId(CCRegClass, reg_idx)).index(), val);
@@ -403,6 +418,12 @@ class O3ThreadContext : public ThreadContext
     virtual void setVecElemFlat(const RegIndex& idx, const ElemIndex& elemIdx,
                                 const VecElem& val);
 
+    virtual const VecPredRegContainer& readVecPredRegFlat(int idx)
+        const override;
+    virtual VecPredRegContainer& getWritableVecPredRegFlat(int idx) override;
+    virtual void setVecPredRegFlat(int idx,
+                                   const VecPredRegContainer& val) override;
+
     virtual CCReg readCCRegFlat(int idx);
     virtual void setCCRegFlat(int idx, CCReg val);
 };
diff --git a/src/cpu/o3/thread_context_impl.hh b/src/cpu/o3/thread_context_impl.hh
index bd2bf63b0..59562ba3b 100644
--- a/src/cpu/o3/thread_context_impl.hh
+++ b/src/cpu/o3/thread_context_impl.hh
@@ -233,6 +233,20 @@ O3ThreadContext<Impl>::readVecElemFlat(const RegIndex& idx,
 }
 
 template <class Impl>
+const TheISA::VecPredRegContainer&
+O3ThreadContext<Impl>::readVecPredRegFlat(int reg_id) const
+{
+    return cpu->readArchVecPredReg(reg_id, thread->threadId());
+}
+
+template <class Impl>
+TheISA::VecPredRegContainer&
+O3ThreadContext<Impl>::getWritableVecPredRegFlat(int reg_id)
+{
+    return cpu->getWritableArchVecPredReg(reg_id, thread->threadId());
+}
+
+template <class Impl>
 TheISA::CCReg
 O3ThreadContext<Impl>::readCCRegFlat(int reg_idx)
 {
@@ -277,6 +291,16 @@ O3ThreadContext<Impl>::setVecElemFlat(const RegIndex& idx,
 
 template <class Impl>
 void
+O3ThreadContext<Impl>::setVecPredRegFlat(int reg_idx,
+                                         const VecPredRegContainer& val)
+{
+    cpu->setArchVecPredReg(reg_idx, val, thread->threadId());
+
+    conditionalSquash();
+}
+
+template <class Impl>
+void
 O3ThreadContext<Impl>::setCCRegFlat(int reg_idx, TheISA::CCReg val)
 {
     cpu->setArchCCReg(reg_idx, val, thread->threadId());