1 files changed, 138 insertions, 0 deletions
diff --git a/cpu/beta_cpu/rob.hh b/cpu/beta_cpu/rob.hh
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+// Todo: Probably add in support for scheduling events (more than one as
+// well) on the case of the ROB being empty or full.  Considering tracking
+// free entries instead of insts in ROB.  Differentiate between squashing
+// all instructions after the instruction, and all instructions after *and*
+// including that instruction.
+
+#ifndef __ROB_HH__
+#define __ROB_HH__
+
+#include<utility>
+#include<vector>
+
+#include "arch/alpha/isa_traits.hh"
+
+using namespace std;
+
+/**
+ * ROB class.  Uses the instruction list that exists within the CPU to
+ * represent the ROB.  This class doesn't contain that list, but instead
+ * a pointer to the CPU to get access to the list.  The ROB, in this first
+ * implementation, is largely what drives squashing.
+ */
+template <class Impl>
+class ROB
+{
+  public:
+    //Typedefs from the Impl.
+    typedef typename Impl::FullCPU FullCPU;
+    typedef typename Impl::DynInstPtr DynInstPtr;
+
+    typedef pair<RegIndex, PhysRegIndex> UnmapInfo_t;
+    typedef typename list<DynInstPtr>::iterator InstIt_t;
+
+  public:
+    /** ROB constructor.
+     *  @params _numEntries Number of entries in ROB.
+     *  @params _squashWidth Number of instructions that can be squashed in a
+     *                       single cycle.
+     */
+    ROB(unsigned _numEntries, unsigned _squashWidth);
+
+    /** Function to set the CPU pointer, necessary due to which object the ROB
+     *  is created within.
+     *  @params cpu_ptr Pointer to the implementation specific full CPU object.
+     */
+    void setCPU(FullCPU *cpu_ptr);
+
+    /** Function to insert an instruction into the ROB.  The parameter inst is
+     *  not truly required, but is useful for checking correctness.  Note
+     *  that whatever calls this function must ensure that there is enough
+     *  space within the ROB for the new instruction.
+     *  @params inst The instruction being inserted into the ROB.
+     *  @todo Remove the parameter once correctness is ensured.
+     */
+    void insertInst(DynInstPtr &inst);
+
+    /** Returns pointer to the head instruction within the ROB.  There is
+     *  no guarantee as to the return value if the ROB is empty.
+     *  @retval Pointer to the DynInst that is at the head of the ROB.
+     */
+    DynInstPtr readHeadInst() { return cpu->instList.front(); }
+
+    DynInstPtr readTailInst() { return (*tail); }
+
+    void retireHead();
+
+    bool isHeadReady();
+
+    unsigned numFreeEntries();
+
+    bool isFull()
+    { return numInstsInROB == numEntries; }
+
+    bool isEmpty()
+    { return numInstsInROB == 0; }
+
+    void doSquash();
+
+    void squash(InstSeqNum squash_num);
+
+    uint64_t readHeadPC();
+
+    uint64_t readHeadNextPC();
+
+    InstSeqNum readHeadSeqNum();
+
+    uint64_t readTailPC();
+
+    InstSeqNum readTailSeqNum();
+
+    /** Checks if the ROB is still in the process of squashing instructions.
+     *  @retval Whether or not the ROB is done squashing.
+     */
+    bool isDoneSquashing() const { return doneSquashing; }
+
+    /** This is more of a debugging function than anything.  Use
+     *  numInstsInROB to get the instructions in the ROB unless you are
+     *  double checking that variable.
+     */
+    int countInsts();
+
+  private:
+
+    /** Pointer to the CPU. */
+    FullCPU *cpu;
+
+    /** Number of instructions in the ROB. */
+    unsigned numEntries;
+
+    /** Number of instructions that can be squashed in a single cycle. */
+    unsigned squashWidth;
+
+    /** Iterator pointing to the instruction which is the last instruction
+     *  in the ROB.  This may at times be invalid (ie when the ROB is empty),
+     *  however it should never be incorrect.
+     */
+    InstIt_t tail;
+
+    /** Iterator used for walking through the list of instructions when
+     *  squashing.  Used so that there is persistent state between cycles;
+     *  when squashing, the instructions are marked as squashed but not
+     *  immediately removed, meaning the tail iterator remains the same before
+     *  and after a squash.
+     *  This will always be set to cpu->instList.end() if it is invalid.
+     */
+    InstIt_t squashIt;
+
+    /** Number of instructions in the ROB. */
+    int numInstsInROB;
+
+    /** The sequence number of the squashed instruction. */
+    InstSeqNum squashedSeqNum;
+
+    /** Is the ROB done squashing. */
+    bool doneSquashing;
+};
+
+#endif //__ROB_HH__