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authorAndreas Sandberg <Andreas.Sandberg@ARM.com>2013-01-07 13:05:46 -0500
committerAndreas Sandberg <Andreas.Sandberg@ARM.com>2013-01-07 13:05:46 -0500
commit1814a85a055732baf98fd030441bb4c5c5db9bdc (patch)
tree33dd6adc62342a55ac3b0f4dbe9fdb9d82faa323 /src/cpu/o3/bpred_unit_impl.hh
parent9e8003148f78811e600e51a900f96b71cb525b60 (diff)
downloadgem5-1814a85a055732baf98fd030441bb4c5c5db9bdc.tar.xz
cpu: Rewrite O3 draining to avoid stopping in microcode
Previously, the O3 CPU could stop in the middle of a microcode sequence. This patch makes sure that the pipeline stops when it has committed a normal instruction or exited from a microcode sequence. Additionally, it makes sure that the pipeline has no instructions in flight when it is drained, which should make draining more robust. Draining is controlled in the commit stage, which checks if the next PC after a committed instruction is in microcode. If this isn't the case, it requests a squash of all instructions after that the instruction that just committed and immediately signals a drain stall to the fetch stage. The CPU then continues to execute until the pipeline and all associated buffers are empty.
Diffstat (limited to 'src/cpu/o3/bpred_unit_impl.hh')
-rw-r--r--src/cpu/o3/bpred_unit_impl.hh12
1 files changed, 6 insertions, 6 deletions
diff --git a/src/cpu/o3/bpred_unit_impl.hh b/src/cpu/o3/bpred_unit_impl.hh
index 74fe27a6a..43e801710 100644
--- a/src/cpu/o3/bpred_unit_impl.hh
+++ b/src/cpu/o3/bpred_unit_impl.hh
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2011 ARM Limited
+ * Copyright (c) 2011-2012 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
@@ -131,12 +131,12 @@ BPredUnit<Impl>::regStats()
template <class Impl>
void
-BPredUnit<Impl>::switchOut()
+BPredUnit<Impl>::drainSanityCheck() const
{
- // Clear any state upon switch out.
- for (int i = 0; i < Impl::MaxThreads; ++i) {
- squash(0, i);
- }
+ // We shouldn't have any outstanding requests when we resume from
+ // a drained system.
+ for (int i = 0; i < Impl::MaxThreads; ++i)
+ assert(predHist[i].empty());
}
template <class Impl>