2 files changed, 51 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineScheduler.cpp b/llvm/lib/CodeGen/MachineScheduler.cpp
index 6052cdfae37..fe7b2c8399b 100644
--- a/llvm/lib/CodeGen/MachineScheduler.cpp
+++ b/llvm/lib/CodeGen/MachineScheduler.cpp
@@ -1173,6 +1173,12 @@ void ScheduleDAGMILive::schedule() {
         dbgs() << "  Pressure Diff      : ";
         getPressureDiff(&SU).dump(*TRI);
       }
+      dbgs() << "  Single Issue       : ";
+      if (SchedModel.mustBeginGroup(SU.getInstr()) &&
+         SchedModel.mustEndGroup(SU.getInstr()))
+        dbgs() << "true;";
+      else
+        dbgs() << "false;";
       dbgs() << '\n';
     }
     if (ExitSU.getInstr() != nullptr)
@@ -1910,12 +1916,22 @@ bool SchedBoundary::checkHazard(SUnit *SU) {
       && HazardRec->getHazardType(SU) != ScheduleHazardRecognizer::NoHazard) {
     return true;
   }
+
   unsigned uops = SchedModel->getNumMicroOps(SU->getInstr());
   if ((CurrMOps > 0) && (CurrMOps + uops > SchedModel->getIssueWidth())) {
     DEBUG(dbgs() << "  SU(" << SU->NodeNum << ") uops="
           << SchedModel->getNumMicroOps(SU->getInstr()) << '\n');
     return true;
   }
+
+  if (CurrMOps > 0 &&
+      ((isTop() && SchedModel->mustBeginGroup(SU->getInstr())) ||
+       (!isTop() && SchedModel->mustEndGroup(SU->getInstr())))) {
+    DEBUG(dbgs() << "  hazard: SU(" << SU->NodeNum << ") must "
+                 << (isTop()? "begin" : "end") << " group\n");
+    return true;
+  }
+
   if (SchedModel->hasInstrSchedModel() && SU->hasReservedResource) {
     const MCSchedClassDesc *SC = DAG->getSchedClass(SU);
     for (TargetSchedModel::ProcResIter
@@ -2211,6 +2227,18 @@ void SchedBoundary::bumpNode(SUnit *SU) {
   // one cycle.  Since we commonly reach the max MOps here, opportunistically
   // bump the cycle to avoid uselessly checking everything in the readyQ.
   CurrMOps += IncMOps;
+
+  // Bump the cycle count for issue group constraints.
+  // This must be done after NextCycle has been adjust for all other stalls.
+  // Calling bumpCycle(X) will reduce CurrMOps by one issue group and set
+  // currCycle to X.
+  if ((isTop() &&  SchedModel->mustEndGroup(SU->getInstr())) ||
+      (!isTop() && SchedModel->mustBeginGroup(SU->getInstr()))) {
+    DEBUG(dbgs() << "  Bump cycle to "
+                 << (isTop() ? "end" : "begin") << " group\n");
+    bumpCycle(++NextCycle);
+  }
+
   while (CurrMOps >= SchedModel->getIssueWidth()) {
     DEBUG(dbgs() << "  *** Max MOps " << CurrMOps
           << " at cycle " << CurrCycle << '\n');
diff --git a/llvm/lib/CodeGen/TargetSchedule.cpp b/llvm/lib/CodeGen/TargetSchedule.cpp
index a4dd753975c..04edf0e6285 100644
--- a/llvm/lib/CodeGen/TargetSchedule.cpp
+++ b/llvm/lib/CodeGen/TargetSchedule.cpp
@@ -84,6 +84,29 @@ void TargetSchedModel::init(const MCSchedModel &sm,
   }
 }
 
+/// Returns true only if instruction is specified as single issue.
+bool TargetSchedModel::mustBeginGroup(const MachineInstr *MI,
+                                     const MCSchedClassDesc *SC) const {
+  if (hasInstrSchedModel()) {
+    if (!SC)
+      SC = resolveSchedClass(MI);
+    if (SC->isValid())
+      return SC->BeginGroup;
+  }
+  return false;
+}
+
+bool TargetSchedModel::mustEndGroup(const MachineInstr *MI,
+                                     const MCSchedClassDesc *SC) const {
+  if (hasInstrSchedModel()) {
+    if (!SC)
+      SC = resolveSchedClass(MI);
+    if (SC->isValid())
+      return SC->EndGroup;
+  }
+  return false;
+}
+
 unsigned TargetSchedModel::getNumMicroOps(const MachineInstr *MI,
                                           const MCSchedClassDesc *SC) const {
   if (hasInstrItineraries()) {