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-rw-r--r--lib/CodeGen/MachineScheduler.cpp356
1 files changed, 100 insertions, 256 deletions
diff --git a/lib/CodeGen/MachineScheduler.cpp b/lib/CodeGen/MachineScheduler.cpp
index 4704dae..e36c7d4 100644
--- a/lib/CodeGen/MachineScheduler.cpp
+++ b/lib/CodeGen/MachineScheduler.cpp
@@ -18,11 +18,7 @@
#include "llvm/CodeGen/MachineScheduler.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/RegisterClassInfo.h"
-#include "llvm/CodeGen/RegisterPressure.h"
-#include "llvm/CodeGen/ScheduleDAGInstrs.h"
#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
-#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/MC/MCInstrItineraries.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
@@ -35,10 +31,12 @@
using namespace llvm;
-static cl::opt<bool> ForceTopDown("misched-topdown", cl::Hidden,
- cl::desc("Force top-down list scheduling"));
-static cl::opt<bool> ForceBottomUp("misched-bottomup", cl::Hidden,
- cl::desc("Force bottom-up list scheduling"));
+namespace llvm {
+cl::opt<bool> ForceTopDown("misched-topdown", cl::Hidden,
+ cl::desc("Force top-down list scheduling"));
+cl::opt<bool> ForceBottomUp("misched-bottomup", cl::Hidden,
+ cl::desc("Force bottom-up list scheduling"));
+}
#ifndef NDEBUG
static cl::opt<bool> ViewMISchedDAGs("view-misched-dags", cl::Hidden,
@@ -281,157 +279,20 @@ void MachineScheduler::print(raw_ostream &O, const Module* m) const {
// unimplemented
}
-//===----------------------------------------------------------------------===//
-// MachineSchedStrategy - Interface to a machine scheduling algorithm.
-//===----------------------------------------------------------------------===//
-
-namespace {
-class ScheduleDAGMI;
-
-/// MachineSchedStrategy - Interface used by ScheduleDAGMI to drive the selected
-/// scheduling algorithm.
-///
-/// If this works well and targets wish to reuse ScheduleDAGMI, we may expose it
-/// in ScheduleDAGInstrs.h
-class MachineSchedStrategy {
-public:
- virtual ~MachineSchedStrategy() {}
-
- /// Initialize the strategy after building the DAG for a new region.
- virtual void initialize(ScheduleDAGMI *DAG) = 0;
-
- /// Pick the next node to schedule, or return NULL. Set IsTopNode to true to
- /// schedule the node at the top of the unscheduled region. Otherwise it will
- /// be scheduled at the bottom.
- virtual SUnit *pickNode(bool &IsTopNode) = 0;
-
- /// Notify MachineSchedStrategy that ScheduleDAGMI has scheduled a node.
- virtual void schedNode(SUnit *SU, bool IsTopNode) = 0;
-
- /// When all predecessor dependencies have been resolved, free this node for
- /// top-down scheduling.
- virtual void releaseTopNode(SUnit *SU) = 0;
- /// When all successor dependencies have been resolved, free this node for
- /// bottom-up scheduling.
- virtual void releaseBottomNode(SUnit *SU) = 0;
-};
-} // namespace
+#ifndef NDEBUG
+void ReadyQueue::dump() {
+ dbgs() << Name << ": ";
+ for (unsigned i = 0, e = Queue.size(); i < e; ++i)
+ dbgs() << Queue[i]->NodeNum << " ";
+ dbgs() << "\n";
+}
+#endif
//===----------------------------------------------------------------------===//
// ScheduleDAGMI - Base class for MachineInstr scheduling with LiveIntervals
// preservation.
//===----------------------------------------------------------------------===//
-namespace {
-/// ScheduleDAGMI is an implementation of ScheduleDAGInstrs that schedules
-/// machine instructions while updating LiveIntervals.
-class ScheduleDAGMI : public ScheduleDAGInstrs {
- AliasAnalysis *AA;
- RegisterClassInfo *RegClassInfo;
- MachineSchedStrategy *SchedImpl;
-
- MachineBasicBlock::iterator LiveRegionEnd;
-
- /// Register pressure in this region computed by buildSchedGraph.
- IntervalPressure RegPressure;
- RegPressureTracker RPTracker;
-
- /// List of pressure sets that exceed the target's pressure limit before
- /// scheduling, listed in increasing set ID order. Each pressure set is paired
- /// with its max pressure in the currently scheduled regions.
- std::vector<PressureElement> RegionCriticalPSets;
-
- /// 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;
-
-#ifndef NDEBUG
- /// The number of instructions scheduled so far. Used to cut off the
- /// scheduler at the point determined by misched-cutoff.
- unsigned NumInstrsScheduled;
-#endif
-public:
- 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(), TopRPTracker(TopPressure),
- CurrentBottom(), BotRPTracker(BotPressure) {
-#ifndef NDEBUG
- NumInstrsScheduled = 0;
-#endif
- }
-
- ~ScheduleDAGMI() {
- delete SchedImpl;
- }
-
- MachineBasicBlock::iterator top() const { return CurrentTop; }
- MachineBasicBlock::iterator bottom() const { return CurrentBottom; }
-
- /// Implement the ScheduleDAGInstrs interface for handling the next scheduling
- /// region. This covers all instructions in a block, while schedule() may only
- /// cover a subset.
- void enterRegion(MachineBasicBlock *bb,
- MachineBasicBlock::iterator begin,
- MachineBasicBlock::iterator end,
- unsigned endcount);
-
- /// Implement ScheduleDAGInstrs interface for scheduling a sequence of
- /// reorderable instructions.
- void schedule();
-
- /// Get current register pressure for the top scheduled instructions.
- const IntervalPressure &getTopPressure() const { return TopPressure; }
- const RegPressureTracker &getTopRPTracker() const { return TopRPTracker; }
-
- /// Get current register pressure for the bottom scheduled instructions.
- const IntervalPressure &getBotPressure() const { return BotPressure; }
- const RegPressureTracker &getBotRPTracker() const { return BotRPTracker; }
-
- /// Get register pressure for the entire scheduling region before scheduling.
- const IntervalPressure &getRegPressure() const { return RegPressure; }
-
- const std::vector<PressureElement> &getRegionCriticalPSets() const {
- return RegionCriticalPSets;
- }
-
- /// getIssueWidth - Return the max instructions per scheduling group.
- unsigned getIssueWidth() const {
- return (InstrItins && InstrItins->SchedModel)
- ? InstrItins->SchedModel->IssueWidth : 1;
- }
-
- /// getNumMicroOps - Return the number of issue slots required for this MI.
- unsigned getNumMicroOps(MachineInstr *MI) const {
- if (!InstrItins) return 1;
- int UOps = InstrItins->getNumMicroOps(MI->getDesc().getSchedClass());
- return (UOps >= 0) ? UOps : TII->getNumMicroOps(InstrItins, MI);
- }
-
-protected:
- void initRegPressure();
- void updateScheduledPressure(std::vector<unsigned> NewMaxPressure);
-
- void moveInstruction(MachineInstr *MI, MachineBasicBlock::iterator InsertPos);
- bool checkSchedLimit();
-
- void releaseRoots();
-
- void releaseSucc(SUnit *SU, SDep *SuccEdge);
- void releaseSuccessors(SUnit *SU);
- void releasePred(SUnit *SU, SDep *PredEdge);
- void releasePredecessors(SUnit *SU);
-
- void placeDebugValues();
-};
-} // namespace
-
/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. When
/// NumPredsLeft reaches zero, release the successor node.
///
@@ -565,6 +426,9 @@ void ScheduleDAGMI::initRegPressure() {
std::vector<unsigned> RegionPressure = RPTracker.getPressure().MaxSetPressure;
for (unsigned i = 0, e = RegionPressure.size(); i < e; ++i) {
unsigned Limit = TRI->getRegPressureSetLimit(i);
+ DEBUG(dbgs() << TRI->getRegPressureSetName(i)
+ << "Limit " << Limit
+ << " Actual " << RegionPressure[i] << "\n");
if (RegionPressure[i] > Limit)
RegionCriticalPSets.push_back(PressureElement(i, 0));
}
@@ -610,7 +474,39 @@ void ScheduleDAGMI::releaseRoots() {
/// 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.
+///
+/// This is a skeletal driver, with all the functionality pushed into helpers,
+/// so that it can be easilly extended by experimental schedulers. Generally,
+/// implementing MachineSchedStrategy should be sufficient to implement a new
+/// scheduling algorithm. However, if a scheduler further subclasses
+/// ScheduleDAGMI then it will want to override this virtual method in order to
+/// update any specialized state.
void ScheduleDAGMI::schedule() {
+ buildDAGWithRegPressure();
+
+ DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
+ SUnits[su].dumpAll(this));
+
+ if (ViewMISchedDAGs) viewGraph();
+
+ initQueues();
+
+ bool IsTopNode = false;
+ while (SUnit *SU = SchedImpl->pickNode(IsTopNode)) {
+ if (!checkSchedLimit())
+ break;
+
+ scheduleMI(SU, IsTopNode);
+
+ updateQueues(SU, IsTopNode);
+ }
+ assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone.");
+
+ placeDebugValues();
+}
+
+/// Build the DAG and setup three register pressure trackers.
+void ScheduleDAGMI::buildDAGWithRegPressure() {
// Initialize the register pressure tracker used by buildSchedGraph.
RPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd);
@@ -620,15 +516,15 @@ void ScheduleDAGMI::schedule() {
// Build the DAG, and compute current register pressure.
buildSchedGraph(AA, &RPTracker);
+ if (ViewMISchedDAGs) viewGraph();
// Initialize top/bottom trackers after computing region pressure.
initRegPressure();
+}
- DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
- SUnits[su].dumpAll(this));
-
- if (ViewMISchedDAGs) viewGraph();
-
+/// Identify DAG roots and setup scheduler queues.
+void ScheduleDAGMI::initQueues() {
+ // Initialize the strategy before modifying the DAG.
SchedImpl->initialize(this);
// Release edges from the special Entry node or to the special Exit node.
@@ -640,59 +536,60 @@ void ScheduleDAGMI::schedule() {
CurrentTop = nextIfDebug(RegionBegin, RegionEnd);
CurrentBottom = RegionEnd;
- bool IsTopNode = false;
- while (SUnit *SU = SchedImpl->pickNode(IsTopNode)) {
- if (!checkSchedLimit())
- break;
-
- // Move the instruction to its new location in the instruction stream.
- MachineInstr *MI = SU->getInstr();
-
- if (IsTopNode) {
- assert(SU->isTopReady() && "node still has unscheduled dependencies");
- if (&*CurrentTop == MI)
- CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom);
- else {
- moveInstruction(MI, CurrentTop);
- TopRPTracker.setPos(MI);
- }
+}
- // Update top scheduled pressure.
- TopRPTracker.advance();
- assert(TopRPTracker.getPos() == CurrentTop && "out of sync");
- updateScheduledPressure(TopRPTracker.getPressure().MaxSetPressure);
+/// Move an instruction and update register pressure.
+void ScheduleDAGMI::scheduleMI(SUnit *SU, bool IsTopNode) {
+ // Move the instruction to its new location in the instruction stream.
+ MachineInstr *MI = SU->getInstr();
- // Release dependent instructions for scheduling.
- releaseSuccessors(SU);
+ if (IsTopNode) {
+ assert(SU->isTopReady() && "node still has unscheduled dependencies");
+ if (&*CurrentTop == MI)
+ CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom);
+ else {
+ moveInstruction(MI, CurrentTop);
+ TopRPTracker.setPos(MI);
}
+
+ // Update top scheduled pressure.
+ TopRPTracker.advance();
+ assert(TopRPTracker.getPos() == CurrentTop && "out of sync");
+ updateScheduledPressure(TopRPTracker.getPressure().MaxSetPressure);
+ }
+ else {
+ assert(SU->isBottomReady() && "node still has unscheduled dependencies");
+ MachineBasicBlock::iterator priorII =
+ priorNonDebug(CurrentBottom, CurrentTop);
+ if (&*priorII == MI)
+ CurrentBottom = priorII;
else {
- assert(SU->isBottomReady() && "node still has unscheduled dependencies");
- MachineBasicBlock::iterator priorII =
- priorNonDebug(CurrentBottom, CurrentTop);
- if (&*priorII == MI)
- CurrentBottom = priorII;
- else {
- if (&*CurrentTop == MI) {
- CurrentTop = nextIfDebug(++CurrentTop, priorII);
- TopRPTracker.setPos(CurrentTop);
- }
- moveInstruction(MI, CurrentBottom);
- CurrentBottom = MI;
+ if (&*CurrentTop == MI) {
+ CurrentTop = nextIfDebug(++CurrentTop, priorII);
+ TopRPTracker.setPos(CurrentTop);
}
- // Update bottom scheduled pressure.
- BotRPTracker.recede();
- assert(BotRPTracker.getPos() == CurrentBottom && "out of sync");
- updateScheduledPressure(BotRPTracker.getPressure().MaxSetPressure);
-
- // Release dependent instructions for scheduling.
- releasePredecessors(SU);
+ moveInstruction(MI, CurrentBottom);
+ CurrentBottom = MI;
}
- SU->isScheduled = true;
- SchedImpl->schedNode(SU, IsTopNode);
+ // Update bottom scheduled pressure.
+ BotRPTracker.recede();
+ assert(BotRPTracker.getPos() == CurrentBottom && "out of sync");
+ updateScheduledPressure(BotRPTracker.getPressure().MaxSetPressure);
}
- assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone.");
+}
- placeDebugValues();
+/// Update scheduler queues after scheduling an instruction.
+void ScheduleDAGMI::updateQueues(SUnit *SU, bool IsTopNode) {
+ // Release dependent instructions for scheduling.
+ if (IsTopNode)
+ releaseSuccessors(SU);
+ else
+ releasePredecessors(SU);
+
+ SU->isScheduled = true;
+
+ // Notify the scheduling strategy after updating the DAG.
+ SchedImpl->schedNode(SU, IsTopNode);
}
/// Reinsert any remaining debug_values, just like the PostRA scheduler.
@@ -721,59 +618,6 @@ void ScheduleDAGMI::placeDebugValues() {
//===----------------------------------------------------------------------===//
namespace {
-/// ReadyQueue encapsulates vector of "ready" SUnits with basic convenience
-/// methods for pushing and removing nodes. ReadyQueue's are uniquely identified
-/// by an ID. SUnit::NodeQueueId is a mask of the ReadyQueues the SUnit is in.
-class ReadyQueue {
- unsigned ID;
- std::string Name;
- std::vector<SUnit*> Queue;
-
-public:
- ReadyQueue(unsigned id, const Twine &name): ID(id), Name(name.str()) {}
-
- unsigned getID() const { return ID; }
-
- StringRef getName() const { return Name; }
-
- // SU is in this queue if it's NodeQueueID is a superset of this ID.
- bool isInQueue(SUnit *SU) const { return (SU->NodeQueueId & ID); }
-
- bool empty() const { return Queue.empty(); }
-
- unsigned size() const { return Queue.size(); }
-
- typedef std::vector<SUnit*>::iterator iterator;
-
- iterator begin() { return Queue.begin(); }
-
- iterator end() { return Queue.end(); }
-
- iterator find(SUnit *SU) {
- return std::find(Queue.begin(), Queue.end(), SU);
- }
-
- void push(SUnit *SU) {
- Queue.push_back(SU);
- SU->NodeQueueId |= ID;
- }
-
- void remove(iterator I) {
- (*I)->NodeQueueId &= ~ID;
- *I = Queue.back();
- Queue.pop_back();
- }
-
-#ifndef NDEBUG
- void dump() {
- dbgs() << Name << ": ";
- for (unsigned i = 0, e = Queue.size(); i < e; ++i)
- dbgs() << Queue[i]->NodeNum << " ";
- dbgs() << "\n";
- }
-#endif
-};
-
/// ConvergingScheduler shrinks the unscheduled zone using heuristics to balance
/// the schedule.
class ConvergingScheduler : public MachineSchedStrategy {
generated by cgit v1.1 at 2025-01-09 03:18:11 +0000