Support for draining, and the new method of switching out. Now switching out happens after the pipeline has been drained, deferring the three way handshake to the normal drain mechanism. The calls of switchOut() and takeOverFrom() both take action immediately.

src/cpu/o3/commit.hh:
src/cpu/o3/commit_impl.hh:
src/cpu/o3/cpu.cc:
src/cpu/o3/cpu.hh:
src/cpu/o3/decode.hh:
src/cpu/o3/decode_impl.hh:
src/cpu/o3/fetch.hh:
src/cpu/o3/fetch_impl.hh:
src/cpu/o3/iew.hh:
src/cpu/o3/iew_impl.hh:
src/cpu/o3/rename.hh:
src/cpu/o3/rename_impl.hh:
    Support for draining, new method of switching out.

--HG--
extra : convert_revision : 05bf8b271ec85b3e2c675c3bed6c42aeba21f465

1 files changed, 17 insertions, 7 deletions

diff --git a/src/cpu/o3/fetch_impl.hh b/src/cpu/o3/fetch_impl.hh
index 60eb76d17..500b5304e 100644
--- a/src/cpu/o3/fetch_impl.hh
+++ b/src/cpu/o3/fetch_impl.hh
@@ -109,6 +109,7 @@ DefaultFetch<Impl>::DefaultFetch(Params *params)
       numThreads(params->numberOfThreads),
       numFetchingThreads(params->smtNumFetchingThreads),
       interruptPending(false),
+      drainPending(false),
       switchedOut(false)
 {
     if (numThreads > Impl::MaxThreads)
@@ -353,7 +354,8 @@ DefaultFetch<Impl>::processCacheCompletion(PacketPtr pkt)
     // to return.
     if (fetchStatus[tid] != IcacheWaitResponse ||
         pkt->req != memReq[tid] ||
-        isSwitchedOut()) {
+        isSwitchedOut() ||
+        drainPending) {
         ++fetchIcacheSquashes;
         delete pkt->req;
         delete pkt;
@@ -384,17 +386,25 @@ DefaultFetch<Impl>::processCacheCompletion(PacketPtr pkt)
 
 template <class Impl>
 void
-DefaultFetch<Impl>::switchOut()
+DefaultFetch<Impl>::drain()
 {
-    // Fetch is ready to switch out at any time.
-    switchedOut = true;
-    cpu->signalSwitched();
+    // Fetch is ready to drain at any time.
+    cpu->signalDrained();
+    drainPending = true;
 }
 
 template <class Impl>
 void
-DefaultFetch<Impl>::doSwitchOut()
+DefaultFetch<Impl>::resume()
 {
+    drainPending = false;
+}
+
+template <class Impl>
+void
+DefaultFetch<Impl>::switchOut()
+{
+    switchedOut = true;
     // Branch predictor needs to have its state cleared.
     branchPred.switchOut();
 }
@@ -498,7 +508,7 @@ DefaultFetch<Impl>::fetchCacheLine(Addr fetch_PC, Fault &ret_fault, unsigned tid
     unsigned flags = 0;
 #endif // FULL_SYSTEM
 
-    if (cacheBlocked || (interruptPending && flags == 0) || switchedOut) {
+    if (cacheBlocked || (interruptPending && flags == 0) || drainPending) {
         // Hold off fetch from getting new instructions when:
         // Cache is blocked, or
         // while an interrupt is pending and we're not in PAL mode, or