[llvm-commits] [llvm] r156571 - in /llvm/trunk/lib/CodeGen: MachineScheduler.cpp RegisterPressure.cpp RegisterPressure.h
Andrew Trick
atrick at apple.com
Thu May 10 14:06:10 PDT 2012
Author: atrick
Date: Thu May 10 16:06:10 2012
New Revision: 156571
URL: http://llvm.org/viewvc/llvm-project?rev=156571&view=rev
Log:
misched: Introducing Top and Bottom register pressure trackers during scheduling.
Modified:
llvm/trunk/lib/CodeGen/MachineScheduler.cpp
llvm/trunk/lib/CodeGen/RegisterPressure.cpp
llvm/trunk/lib/CodeGen/RegisterPressure.h
Modified: llvm/trunk/lib/CodeGen/MachineScheduler.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineScheduler.cpp?rev=156571&r1=156570&r2=156571&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineScheduler.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineScheduler.cpp Thu May 10 16:06:10 2012
@@ -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);
+
+ // Account for liveness generate by the region boundary.
+ if (LiveRegionEnd != RegionEnd)
+ RPTracker.recede();
- // Build the DAG.
+ // 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);
}
Modified: llvm/trunk/lib/CodeGen/RegisterPressure.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegisterPressure.cpp?rev=156571&r1=156570&r2=156571&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegisterPressure.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegisterPressure.cpp Thu May 10 16:06:10 2012
@@ -337,6 +337,22 @@
}
}
+/// Force liveness of registers.
+void RegPressureTracker::addLiveRegs(ArrayRef<unsigned> Regs) {
+ for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
+ if (TargetRegisterInfo::isVirtualRegister(Regs[i])) {
+ if (LiveVirtRegs.insert(Regs[i]).second)
+ increaseVirtRegPressure(Regs[i]);
+ }
+ else {
+ if (!hasRegAlias(Regs[i], LivePhysRegs, TRI)) {
+ LivePhysRegs.insert(Regs[i]);
+ increasePhysRegPressure(Regs[i]);
+ }
+ }
+ }
+}
+
/// Add PhysReg to the live in set and increase max pressure.
void RegPressureTracker::discoverPhysLiveIn(unsigned Reg) {
assert(!LivePhysRegs.count(Reg) && "avoid bumping max pressure twice");
@@ -607,28 +623,14 @@
decreaseVirtRegPressure(VirtRegOpers.DeadDefs);
// Kill liveness at live defs.
- // TODO: consider earlyclobbers?
- for (unsigned i = 0; i < PhysRegOpers.Defs.size(); ++i) {
- unsigned Reg = PhysRegOpers.Defs[i];
- if (LivePhysRegs.erase(Reg))
- decreasePhysRegPressure(Reg);
- else
- discoverPhysLiveOut(Reg);
- }
- for (unsigned i = 0; i < VirtRegOpers.Defs.size(); ++i) {
- unsigned Reg = VirtRegOpers.Defs[i];
- if (LiveVirtRegs.erase(Reg))
- decreaseVirtRegPressure(Reg);
- else
- discoverVirtLiveOut(Reg);
- }
+ decreasePhysRegPressure(PhysRegOpers.Defs);
+ decreaseVirtRegPressure(VirtRegOpers.Defs);
// Generate liveness for uses.
for (unsigned i = 0, e = PhysRegOpers.Uses.size(); i < e; ++i) {
unsigned Reg = PhysRegOpers.Uses[i];
if (!hasRegAlias(Reg, LivePhysRegs, TRI)) {
increasePhysRegPressure(Reg);
- LivePhysRegs.insert(Reg);
}
}
for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
Modified: llvm/trunk/lib/CodeGen/RegisterPressure.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegisterPressure.h?rev=156571&r1=156570&r2=156571&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegisterPressure.h (original)
+++ llvm/trunk/lib/CodeGen/RegisterPressure.h Thu May 10 16:06:10 2012
@@ -159,9 +159,19 @@
const LiveIntervals *lis, const MachineBasicBlock *mbb,
MachineBasicBlock::const_iterator pos);
- // Get the MI position corresponding to this register pressure.
+ /// Force liveness of registers. Particularly useful to initialize the
+ /// livein/out state of the tracker before the first call to advance/recede.
+ void addLiveRegs(ArrayRef<unsigned> Regs);
+
+ /// Get the MI position corresponding to this register pressure.
MachineBasicBlock::const_iterator getPos() const { return CurrPos; }
+ // Reset the MI position corresponding to the register pressure. This allows
+ // schedulers to move instructions above the RegPressureTracker's
+ // CurrPos. Since the pressure is computed before CurrPos, the iterator
+ // position changes while pressure does not.
+ void setPos(MachineBasicBlock::const_iterator Pos) { CurrPos = Pos; }
+
/// Recede across the previous instruction.
bool recede();
@@ -176,6 +186,18 @@
/// or if closeRegion() was explicitly invoked.
RegisterPressure &getPressure() { return P; }
+ void discoverPhysLiveIn(unsigned Reg);
+ void discoverPhysLiveOut(unsigned Reg);
+
+ void discoverVirtLiveIn(unsigned Reg);
+ void discoverVirtLiveOut(unsigned Reg);
+
+ bool isTopClosed() const;
+ bool isBottomClosed() const;
+
+ void closeTop();
+ void closeBottom();
+
/// Consider the pressure increase caused by traversing this instruction
/// bottom-up. Find the pressure set with the most change beyond its pressure
/// limit based on the tracker's current pressure, and record the number of
@@ -201,23 +223,11 @@
}
protected:
- bool isTopClosed() const;
- bool isBottomClosed() const;
-
- void closeTop();
- void closeBottom();
-
void increasePhysRegPressure(ArrayRef<unsigned> Regs);
void decreasePhysRegPressure(ArrayRef<unsigned> Regs);
void increaseVirtRegPressure(ArrayRef<unsigned> Regs);
void decreaseVirtRegPressure(ArrayRef<unsigned> Regs);
-
- void discoverPhysLiveIn(unsigned Reg);
- void discoverPhysLiveOut(unsigned Reg);
-
- void discoverVirtLiveIn(unsigned Reg);
- void discoverVirtLiveOut(unsigned Reg);
};
} // end namespace llvm
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