Tuan Ta has submitted this change and it was merged. (
https://gem5-review.googlesource.com/c/public/gem5/+/9626 )
Change subject: cpu: fix how branching is handled when a thread is
suspended in MinorCPU
......................................................................
cpu: fix how branching is handled when a thread is suspended in MinorCPU
When a thread is suspended, all instructions after the suspension need
to be discarded since the thread will take a different execution stream
when it wakes up.
To do that, in MinorCPU, whenever a thread gets suspended, we change the
current execution stream by updating the current branch with
BranchData::SuspendThread reason.
Change-Id: I7cdcda22c1cf6e8ac8db8800b7d9ec052433fdf3
Reviewed-on: https://gem5-review.googlesource.com/c/9626
Reviewed-by: Jason Lowe-Power <[email protected]>
Reviewed-by: Giacomo Gabrielli <[email protected]>
Maintainer: Jason Lowe-Power <[email protected]>
---
M src/cpu/minor/execute.cc
1 file changed, 9 insertions(+), 3 deletions(-)
Approvals:
Jason Lowe-Power: Looks good to me, approved; Looks good to me, approved
Giacomo Gabrielli: Looks good to me, approved
diff --git a/src/cpu/minor/execute.cc b/src/cpu/minor/execute.cc
index d7cb475..234a233 100644
--- a/src/cpu/minor/execute.cc
+++ b/src/cpu/minor/execute.cc
@@ -248,7 +248,14 @@
pc_before, target);
}
- if (inst->predictedTaken && !force_branch) {
+ if (thread->status() == ThreadContext::Suspended) {
+ /* Thread got suspended */
+ DPRINTF(Branch, "Thread got suspended: branch from 0x%x to 0x%x "
+ "inst: %s\n",
+ inst->pc.instAddr(), target.instAddr(), *inst);
+
+ reason = BranchData::SuspendThread;
+ } else if (inst->predictedTaken && !force_branch) {
/* Predicted to branch */
if (!must_branch) {
/* No branch was taken, change stream to get us back to the
@@ -1054,8 +1061,7 @@
!branch.isStreamChange() && /* No real branch */
fault == NoFault && /* No faults */
completed_inst && /* Still finding instructions to execute */
- num_insts_committed != commitLimit && /* Not reached commit limit
*/
- cpu.getContext(thread_id)->status() != ThreadContext::Suspended
+ num_insts_committed != commitLimit /* Not reached commit limit */
)
{
if (only_commit_microops) {
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-Change-Id: I7cdcda22c1cf6e8ac8db8800b7d9ec052433fdf3
Gerrit-Change-Number: 9626
Gerrit-PatchSet: 10
Gerrit-Owner: Tuan Ta <[email protected]>
Gerrit-Assignee: Giacomo Gabrielli <[email protected]>
Gerrit-Reviewer: Giacomo Gabrielli <[email protected]>
Gerrit-Reviewer: Giacomo Travaglini <[email protected]>
Gerrit-Reviewer: Jason Lowe-Power <[email protected]>
Gerrit-Reviewer: Tuan Ta <[email protected]>
Gerrit-MessageType: merged
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