cpu/beta_cpu/rename.hh

   1 // Todo:
   2 // Figure out rename map for reg vs fp (probably just have one rename map).
   3 // In simple case, there is no renaming, so have this stage do basically
   4 // nothing.
   5 // Fix up trap and barrier handling.  Fix up squashing too, as it's too
   6 // dependent upon the iew stage continually telling it to squash.
   7 // Have commit send back information whenever a branch has committed.  This
   8 // way the history buffer can be cleared beyond the point where the branch
   9 // was.
  10
  11 #ifndef __SIMPLE_RENAME_HH__
  12 #define __SIMPLE_RENAME_HH__
  13
  14 //Will want to include: time buffer, structs, free list, rename map
  15 #include <list>
  16
  17 #include "base/timebuf.hh"
  18 #include "cpu/beta_cpu/comm.hh"
  19 #include "cpu/beta_cpu/rename_map.hh"
  20 #include "cpu/beta_cpu/free_list.hh"
  21
  22 using namespace std;
  23
  24 // Will need rename maps for both the int reg file and fp reg file.
  25 // Or change rename map class to handle both. (RegFile handles both.)
  26 template<class Impl>
  27 class SimpleRename
  28 {
  29   public:
  30     // Typedefs from the Impl.
  31     typedef typename Impl::ISA ISA;
  32     typedef typename Impl::CPUPol CPUPol;
  33     typedef typename Impl::DynInst DynInst;
  34     typedef typename Impl::FullCPU FullCPU;
  35     typedef typename Impl::Params Params;
  36
  37     typedef typename Impl::FetchStruct FetchStruct;
  38     typedef typename Impl::DecodeStruct DecodeStruct;
  39     typedef typename Impl::RenameStruct RenameStruct;
  40     typedef typename Impl::TimeStruct TimeStruct;
  41
  42     // Typedefs from the CPUPol
  43     typedef typename CPUPol::FreeList FreeList;
  44     typedef typename CPUPol::RenameMap RenameMap;
  45
  46     // Typedefs from the ISA.
  47     typedef typename ISA::Addr Addr;
  48
  49   public:
  50     // Rename will block if ROB becomes full or issue queue becomes full,
  51     // or there are no free registers to rename to.
  52     // Only case where rename squashes is if IEW squashes.
  53     enum Status {
  54         Running,
  55         Idle,
  56         Squashing,
  57         Blocked,
  58         Unblocking,
  59         BarrierStall
  60     };
  61
  62   private:
  63     Status _status;
  64
  65   public:
  66     SimpleRename(Params &params);
  67
  68     void setCPU(FullCPU *cpu_ptr);
  69
  70     void setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr);
  71
  72     void setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr);
  73
  74     void setDecodeQueue(TimeBuffer<DecodeStruct> *dq_ptr);
  75
  76     void setRenameMap(RenameMap *rm_ptr);
  77
  78     void setFreeList(FreeList *fl_ptr);
  79
  80     void dumpHistory();
  81
  82     void tick();
  83
  84     void rename();
  85
  86     void squash();
  87
  88   private:
  89     void block();
  90
  91     inline void unblock();
  92
  93     void doSquash();
  94
  95     void removeFromHistory(InstSeqNum inst_seq_num);
  96
  97     /** Holds the previous information for each rename.
  98      *  Note that often times the inst may have been deleted, so only access
  99      *  the pointer for the address and do not dereference it.
 100      */
 101     struct RenameHistory {
 102         RenameHistory(InstSeqNum _instSeqNum, RegIndex _archReg,
 103                       PhysRegIndex _newPhysReg, PhysRegIndex _prevPhysReg)
 104             : instSeqNum(_instSeqNum), archReg(_archReg),
 105               newPhysReg(_newPhysReg), prevPhysReg(_prevPhysReg),
 106               placeHolder(false)
 107         {
 108         }
 109
 110         /** Constructor used specifically for cases where a place holder
 111          *  rename history entry is being made.
 112          */
 113         RenameHistory(InstSeqNum _instSeqNum)
 114             : instSeqNum(_instSeqNum), archReg(0), newPhysReg(0),
 115               prevPhysReg(0), placeHolder(true)
 116         {
 117         }
 118
 119         InstSeqNum instSeqNum;
 120         RegIndex archReg;
 121         PhysRegIndex newPhysReg;
 122         PhysRegIndex prevPhysReg;
 123         bool placeHolder;
 124     };
 125
 126     list<RenameHistory> historyBuffer;
 127
 128     /** CPU interface. */
 129     FullCPU *cpu;
 130
 131     // Interfaces to objects outside of rename.
 132     /** Time buffer interface. */
 133     TimeBuffer<TimeStruct> *timeBuffer;
 134
 135     /** Wire to get IEW's output from backwards time buffer. */
 136     typename TimeBuffer<TimeStruct>::wire fromIEW;
 137
 138     /** Wire to get commit's output from backwards time buffer. */
 139     typename TimeBuffer<TimeStruct>::wire fromCommit;
 140
 141     /** Wire to write infromation heading to previous stages. */
 142     // Might not be the best name as not only decode will read it.
 143     typename TimeBuffer<TimeStruct>::wire toDecode;
 144
 145     /** Rename instruction queue. */
 146     TimeBuffer<RenameStruct> *renameQueue;
 147
 148     /** Wire to write any information heading to IEW. */
 149     typename TimeBuffer<RenameStruct>::wire toIEW;
 150
 151     /** Decode instruction queue interface. */
 152     TimeBuffer<DecodeStruct> *decodeQueue;
 153
 154     /** Wire to get decode's output from decode queue. */
 155     typename TimeBuffer<DecodeStruct>::wire fromDecode;
 156
 157     /** Skid buffer between rename and decode. */
 158     queue<DecodeStruct> skidBuffer;
 159
 160     /** Rename map interface. */
 161     SimpleRenameMap *renameMap;
 162
 163     /** Free list interface. */
 164     FreeList *freeList;
 165
 166     /** Delay between iew and rename, in ticks. */
 167     int iewToRenameDelay;
 168
 169     /** Delay between decode and rename, in ticks. */
 170     int decodeToRenameDelay;
 171
 172     /** Delay between commit and rename, in ticks. */
 173     unsigned commitToRenameDelay;
 174
 175     /** Rename width, in instructions. */
 176     unsigned renameWidth;
 177
 178     /** Commit width, in instructions.  Used so rename knows how many
 179      *  instructions might have freed registers in the previous cycle.
 180      */
 181     unsigned commitWidth;
 182 };
 183
 184 #endif // __SIMPLE_RENAME_HH__