misched: Introducing Top and Bottom register pressure trackers during scheduling.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156571 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineScheduler.cpp b/lib/CodeGen/MachineScheduler.cpp
index 4314e48..7e871a7 100644
--- a/lib/CodeGen/MachineScheduler.cpp
+++ b/lib/CodeGen/MachineScheduler.cpp
@@ -322,15 +322,21 @@
RegisterClassInfo *RegClassInfo;
MachineSchedStrategy *SchedImpl;
+ MachineBasicBlock::iterator LiveRegionEnd;
+
// Register pressure in this region computed by buildSchedGraph.
IntervalPressure RegPressure;
RegPressureTracker RPTracker;
/// The top of the unscheduled zone.
MachineBasicBlock::iterator CurrentTop;
+ IntervalPressure TopPressure;
+ RegPressureTracker TopRPTracker;
/// The bottom of the unscheduled zone.
MachineBasicBlock::iterator CurrentBottom;
+ IntervalPressure BotPressure;
+ RegPressureTracker BotRPTracker;
/// The number of instructions scheduled so far. Used to cut off the
/// scheduler at the point determined by misched-cutoff.
@@ -339,8 +345,8 @@
ScheduleDAGMI(MachineSchedContext *C, MachineSchedStrategy *S):
ScheduleDAGInstrs(*C->MF, *C->MLI, *C->MDT, /*IsPostRA=*/false, C->LIS),
AA(C->AA), RegClassInfo(C->RegClassInfo), SchedImpl(S),
- RPTracker(RegPressure), CurrentTop(), CurrentBottom(),
- NumInstrsScheduled(0) {}
+ RPTracker(RegPressure), CurrentTop(), TopRPTracker(TopPressure),
+ CurrentBottom(), BotRPTracker(BotPressure), NumInstrsScheduled(0) {}
~ScheduleDAGMI() {
delete SchedImpl;
@@ -349,6 +355,15 @@
MachineBasicBlock::iterator top() const { return CurrentTop; }
MachineBasicBlock::iterator bottom() const { return CurrentBottom; }
+ /// Get current register pressure for the top scheduled instructions.
+ const IntervalPressure &getTopPressure() const { return TopPressure; }
+
+ /// Get current register pressure for the bottom scheduled instructions.
+ const IntervalPressure &getBotPressure() const { return BotPressure; }
+
+ /// Get register pressure for the entire scheduling region before scheduling.
+ const IntervalPressure &getRegPressure() const { return RegPressure; }
+
/// Implement the ScheduleDAGInstrs interface for handling the next scheduling
/// region. This covers all instructions in a block, while schedule() may only
/// cover a subset.
@@ -362,6 +377,8 @@
void schedule();
protected:
+ void initRegPressure();
+
void moveInstruction(MachineInstr *MI, MachineBasicBlock::iterator InsertPos);
bool checkSchedLimit();
@@ -436,6 +453,9 @@
// Fix RegionBegin if another instruction moves above the first instruction.
if (RegionBegin == InsertPos)
RegionBegin = MI;
+ // Fix TopRPTracker if we move something above CurrentTop.
+ if (CurrentTop == InsertPos)
+ TopRPTracker.setPos(MI);
}
bool ScheduleDAGMI::checkSchedLimit() {
@@ -459,23 +479,55 @@
unsigned endcount)
{
ScheduleDAGInstrs::enterRegion(bb, begin, end, endcount);
- // Setup the register pressure tracker to begin tracking at the end of this
- // region.
- RPTracker.init(&MF, RegClassInfo, LIS, BB, end);
+
+ // For convenience remember the end of the liveness region.
+ LiveRegionEnd =
+ (RegionEnd == bb->end()) ? RegionEnd : llvm::next(RegionEnd);
+}
+
+// Setup the register pressure trackers for the top scheduled top and bottom
+// scheduled regions.
+void ScheduleDAGMI::initRegPressure() {
+ TopRPTracker.init(&MF, RegClassInfo, LIS, BB, RegionBegin);
+ BotRPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd);
+
+ // Close the RPTracker to finalize live ins.
+ RPTracker.closeRegion();
+
+ // Initialize the live ins and live outs.
+ TopRPTracker.addLiveRegs(RPTracker.getPressure().LiveInRegs);
+ BotRPTracker.addLiveRegs(RPTracker.getPressure().LiveOutRegs);
+
+ // Close one end of the tracker so we can call
+ // getMaxUpward/DownwardPressureDelta before advancing across any
+ // instructions. This converts currently live regs into live ins/outs.
+ TopRPTracker.closeTop();
+ BotRPTracker.closeBottom();
+
+ // Account for liveness generated by the region boundary.
+ if (LiveRegionEnd != RegionEnd)
+ BotRPTracker.recede();
+
+ assert(BotRPTracker.getPos() == RegionEnd && "Can't find the region bottom");
}
/// schedule - Called back from MachineScheduler::runOnMachineFunction
/// after setting up the current scheduling region. [RegionBegin, RegionEnd)
/// only includes instructions that have DAG nodes, not scheduling boundaries.
void ScheduleDAGMI::schedule() {
- while(RPTracker.getPos() != RegionEnd) {
- bool Moved = RPTracker.recede();
- assert(Moved && "Regpressure tracker cannot find RegionEnd"); (void)Moved;
- }
+ // Initialize the register pressure tracker used by buildSchedGraph.
+ RPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd);
- // Build the DAG.
+ // Account for liveness generate by the region boundary.
+ if (LiveRegionEnd != RegionEnd)
+ RPTracker.recede();
+
+ // Build the DAG, and compute current register pressure.
buildSchedGraph(AA, &RPTracker);
+ // Initialize top/bottom trackers after computing region pressure.
+ initRegPressure();
+
DEBUG(dbgs() << "********** MI Scheduling **********\n");
DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
SUnits[su].dumpAll(this));
@@ -517,6 +569,11 @@
CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom);
else
moveInstruction(MI, CurrentTop);
+
+ // Update top scheduled pressure.
+ TopRPTracker.advance();
+ assert(TopRPTracker.getPos() == CurrentTop && "out of sync");
+
// Release dependent instructions for scheduling.
releaseSuccessors(SU);
}
@@ -532,6 +589,10 @@
moveInstruction(MI, CurrentBottom);
CurrentBottom = MI;
}
+ // Update bottom scheduled pressure.
+ BotRPTracker.recede();
+ assert(BotRPTracker.getPos() == CurrentBottom && "out of sync");
+
// Release dependent instructions for scheduling.
releasePredecessors(SU);
}