diff options
| author | Ali Saidi <Ali.Saidi@ARM.com> | 2011-01-18 16:30:05 -0600 |
|---|---|---|
| committer | Ali Saidi <Ali.Saidi@ARM.com> | 2011-01-18 16:30:05 -0600 |
| commit | 1167ef19cf0c478e73fc6e1848f005863525cc13 (patch) | |
| tree | 2756424caa7a54899fdfa9fad45629e9b3784d88 /src/cpu/o3/commit_impl.hh | |
| parent | ea058b14da9f84d9b30f8ef7710d18546fc79db8 (diff) | |
| download | gem5-1167ef19cf0c478e73fc6e1848f005863525cc13.tar.xz | |
O3: Keep around the last committed instruction and use for squashing.
Without this change 0 is always used for the youngest sequence number if
a squash occured and the ROB was empty (E.g. an instruction is marked
serializeAfter or a fetch stall prevents other instructions from issuing).
Using 0 there is a race to rename where an instruction that committed the
same cycle as the squashing instruction can have it's renamed state undone
by the squash using sequence number 0.
Diffstat (limited to 'src/cpu/o3/commit_impl.hh')
| -rw-r--r-- | src/cpu/o3/commit_impl.hh | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/src/cpu/o3/commit_impl.hh b/src/cpu/o3/commit_impl.hh index 78e9a8848..a49e1497e 100644 --- a/src/cpu/o3/commit_impl.hh +++ b/src/cpu/o3/commit_impl.hh @@ -141,6 +141,7 @@ DefaultCommit<Impl>::DefaultCommit(O3CPU *_cpu, DerivO3CPUParams *params) trapSquash[tid] = false; tcSquash[tid] = false; pc[tid].set(0); + lastCommitedSeqNum[tid] = 0; } #if FULL_SYSTEM interrupt = NoFault; @@ -498,12 +499,12 @@ DefaultCommit<Impl>::squashAll(ThreadID tid) // Hopefully this doesn't mess things up. Basically I want to squash // all instructions of this thread. InstSeqNum squashed_inst = rob->isEmpty() ? - 0 : rob->readHeadInst(tid)->seqNum - 1; + lastCommitedSeqNum[tid] : rob->readHeadInst(tid)->seqNum - 1; // All younger instructions will be squashed. Set the sequence // number as the youngest instruction in the ROB (0 in this case. // Hopefully nothing breaks.) - youngestSeqNum[tid] = 0; + youngestSeqNum[tid] = lastCommitedSeqNum[tid]; rob->squash(squashed_inst, tid); changedROBNumEntries[tid] = true; @@ -960,6 +961,9 @@ DefaultCommit<Impl>::commitInsts() TheISA::advancePC(pc[tid], head_inst->staticInst); + // Keep track of the last sequence number commited + lastCommitedSeqNum[tid] = head_inst->seqNum; + // If this is an instruction that doesn't play nicely with // others squash everything and restart fetch if (head_inst->isSquashAfter()) |