Fix the O3CPU to support the multi-pass method for checking if the system has fully drained.

src/cpu/o3/commit.hh:
src/cpu/o3/commit_impl.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:
    Return a value so that the CPU can instantly return from draining if the pipeline is already drained.
src/cpu/o3/cpu.cc:
    Use values returned from pipeline stages so that the CPU can instantly return from draining if the pipeline is already drained.

--HG--
extra : convert_revision : d8ef6b811644ea67c8b40c4719273fa224105811

1 files changed, 9 insertions, 1 deletions

diff --git a/src/cpu/o3/commit_impl.hh b/src/cpu/o3/commit_impl.hh
index 2eb05afac..b50c9a898 100644
--- a/src/cpu/o3/commit_impl.hh
+++ b/src/cpu/o3/commit_impl.hh
@@ -350,10 +350,18 @@ DefaultCommit<Impl>::initStage()
 }
 
 template <class Impl>
-void
+bool
 DefaultCommit<Impl>::drain()
 {
     drainPending = true;
+
+    // If it's already drained, return true.
+    if (rob->isEmpty() && !iewStage->hasStoresToWB()) {
+        cpu->signalDrained();
+        return true;
+    }
+
+    return false;
 }
 
 template <class Impl>