2 files changed, 64 insertions, 0 deletions

diff --git a/src/mem/cache/miss/mshr.cc b/src/mem/cache/miss/mshr.cc
index fc8d2175e..ca5e38601 100644
--- a/src/mem/cache/miss/mshr.cc
+++ b/src/mem/cache/miss/mshr.cc
@@ -75,6 +75,8 @@ MSHR::allocate(Addr _addr, int _size, PacketPtr target,
     assert(deferredTargets.empty());
     deferredNeedsExclusive = false;
     pendingInvalidate = false;
+    replacedPendingUpgrade = false;
+    data = NULL;
 }
 
 void
@@ -171,6 +173,57 @@ MSHR::promoteDeferredTargets()
 
 
 void
+MSHR::handleReplacement(CacheBlk *blk, int blkSize)
+{
+    // must be an outstanding upgrade request on block we're about to
+    // replace...
+    assert(!blk->isWritable());
+    assert(needsExclusive);
+    replacedPendingUpgrade = true;
+
+    // if it's dirty, just remember what happened and allow the
+    // writeback to continue.  we'll reissue a ReadEx later whether
+    // the upgrade succeeds or not
+    if (blk->isDirty()) {
+        replacedPendingUpgradeDirty = true;
+        return;
+    }
+
+    // if not dirty, we need to save it off as it will be only valid
+    // copy in system if upgrade is successful (and may need to be
+    // written back then, as the current owner if any will be
+    // invalidating its block)
+    replacedPendingUpgradeDirty = false;
+    data = new uint8_t[blkSize];
+    std::memcpy(data, blk->data, blkSize);
+}
+
+
+bool
+MSHR::handleReplacedPendingUpgrade(Packet *pkt)
+{
+    // @TODO: if upgrade is nacked and replacedPendingUpgradeDirty is true, then we need to writeback the data (or rel
+    assert(pkt->cmd == MemCmd::UpgradeResp);
+    assert(replacedPendingUpgrade);
+    replacedPendingUpgrade = false; // reset
+    if (replacedPendingUpgradeDirty) {
+        // we wrote back the previous copy; just reissue as a ReadEx
+        return false;
+    }
+
+    // previous copy was not dirty, but we are now owner...  fake out
+    // cache by taking saved data and converting UpgradeResp to
+    // ReadExResp
+    assert(data);
+    pkt->cmd = MemCmd::ReadExResp;
+    pkt->setData(data);
+    delete [] data;
+    data = NULL;
+    return true;
+}
+
+
+void
 MSHR::dump()
 {
     ccprintf(cerr,
diff --git a/src/mem/cache/miss/mshr.hh b/src/mem/cache/miss/mshr.hh
index 92288cf52..a9380d99a 100644
--- a/src/mem/cache/miss/mshr.hh
+++ b/src/mem/cache/miss/mshr.hh
@@ -105,12 +105,20 @@ class MSHR : public Packet::SenderState
 
     bool deferredNeedsExclusive;
     bool pendingInvalidate;
+    /** Is there a pending upgrade that got replaced? */
+    bool replacedPendingUpgrade;
+    bool replacedPendingUpgradeDirty;
 
     /** Thread number of the miss. */
     short threadNum;
     /** The number of currently allocated targets. */
     short ntargets;
 
+
+    /** Data buffer (if needed).  Currently used only for pending
+     * upgrade handling. */
+    uint8_t *data;
+
     /**
      * Pointer to this MSHR on the ready list.
      * @sa MissQueue, MSHRQueue::readyList
@@ -204,6 +212,9 @@ public:
 
     bool promoteDeferredTargets();
 
+    void handleReplacement(CacheBlk *blk, int blkSize);
+    bool handleReplacedPendingUpgrade(Packet *pkt);
+
     /**
      * Prints the contents of this MSHR to stderr.
      */