From ad296b068cf4a0b043988be518994ac6bd7582f0 Mon Sep 17 00:00:00 2001
From: Rekai Gonzalez-Alberquilla <rekai.gonzalezalberquilla@arm.com>
Date: Thu, 22 Sep 2016 10:49:10 +0100
Subject: [PATCH] cpu: Fix the O3 CPU Drain

The drain did not wait until stages were ready again. Therefore, as a
result of messages in the TimeBuffer being drain, the state after the
drain was not consistent and asserts fired in some places when the
draining happened after a stage got blocked, but before the notification
arrived to the previous stages.

Change-Id: Ib50b3b40b7f745b62c1eba2931dec76860824c71
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
---
 src/cpu/o3/decode_impl.hh | 3 ++-
 src/cpu/o3/fetch_impl.hh  | 4 +++-
 src/cpu/o3/iew_impl.hh    | 1 +
 src/cpu/o3/rename_impl.hh | 3 ++-
 4 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/cpu/o3/decode_impl.hh b/src/cpu/o3/decode_impl.hh
index 4ff82da8e..ca56ac1e4 100644
--- a/src/cpu/o3/decode_impl.hh
+++ b/src/cpu/o3/decode_impl.hh
@@ -209,7 +209,8 @@ bool
 DefaultDecode<Impl>::isDrained() const
 {
     for (ThreadID tid = 0; tid < numThreads; ++tid) {
-        if (!insts[tid].empty() || !skidBuffer[tid].empty())
+        if (!insts[tid].empty() || !skidBuffer[tid].empty() ||
+                (decodeStatus[tid] != Running && decodeStatus[tid] != Idle))
             return false;
     }
     return true;
diff --git a/src/cpu/o3/fetch_impl.hh b/src/cpu/o3/fetch_impl.hh
index 3b29d87d4..7631b4c6a 100644
--- a/src/cpu/o3/fetch_impl.hh
+++ b/src/cpu/o3/fetch_impl.hh
@@ -424,8 +424,10 @@ template <class Impl>
 void
 DefaultFetch<Impl>::drainResume()
 {
-    for (ThreadID i = 0; i < numThreads; ++i)
+    for (ThreadID i = 0; i < numThreads; ++i) {
+        stalls[i].decode = false;
         stalls[i].drain = false;
+    }
 }
 
 template <class Impl>
diff --git a/src/cpu/o3/iew_impl.hh b/src/cpu/o3/iew_impl.hh
index e02429b14..78b83eba6 100644
--- a/src/cpu/o3/iew_impl.hh
+++ b/src/cpu/o3/iew_impl.hh
@@ -391,6 +391,7 @@ DefaultIEW<Impl>::isDrained() const
             DPRINTF(Drain, "%i: Skid buffer not empty.\n", tid);
             drained = false;
         }
+        drained = drained && dispatchStatus[tid] == Running;
     }
 
     // Also check the FU pool as instructions are "stored" in FU
diff --git a/src/cpu/o3/rename_impl.hh b/src/cpu/o3/rename_impl.hh
index b6ab4cc3a..00179faae 100644
--- a/src/cpu/o3/rename_impl.hh
+++ b/src/cpu/o3/rename_impl.hh
@@ -304,7 +304,8 @@ DefaultRename<Impl>::isDrained() const
         if (instsInProgress[tid] != 0 ||
             !historyBuffer[tid].empty() ||
             !skidBuffer[tid].empty() ||
-            !insts[tid].empty())
+            !insts[tid].empty() ||
+            (renameStatus[tid] != Idle && renameStatus[tid] != Running))
             return false;
     }
     return true;