From 1fc08f5e9ef733ef1ce6f363fecedc2260e78974 Mon Sep 17 00:00:00 2001
From: dim <dim@FreeBSD.org>
Date: Sat, 14 Apr 2012 13:54:10 +0000
Subject: Vendor import of llvm trunk r154661:
http://llvm.org/svn/llvm-project/llvm/trunk@r154661
---
lib/CodeGen/SelectionDAG/ScheduleDAGVLIW.cpp | 276 +++++++++++++++++++++++++++
1 file changed, 276 insertions(+)
create mode 100644 lib/CodeGen/SelectionDAG/ScheduleDAGVLIW.cpp
(limited to 'lib/CodeGen/SelectionDAG/ScheduleDAGVLIW.cpp')
diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGVLIW.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGVLIW.cpp
new file mode 100644
index 0000000..c851291
--- /dev/null
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGVLIW.cpp
@@ -0,0 +1,276 @@
+//===- ScheduleDAGVLIW.cpp - SelectionDAG list scheduler for VLIW -*- C++ -*-=//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This implements a top-down list scheduler, using standard algorithms.
+// The basic approach uses a priority queue of available nodes to schedule.
+// One at a time, nodes are taken from the priority queue (thus in priority
+// order), checked for legality to schedule, and emitted if legal.
+//
+// Nodes may not be legal to schedule either due to structural hazards (e.g.
+// pipeline or resource constraints) or because an input to the instruction has
+// not completed execution.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "pre-RA-sched"
+#include "ScheduleDAGSDNodes.h"
+#include "llvm/CodeGen/LatencyPriorityQueue.h"
+#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
+#include "llvm/CodeGen/SchedulerRegistry.h"
+#include "llvm/CodeGen/SelectionDAGISel.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/ResourcePriorityQueue.h"
+#include <climits>
+using namespace llvm;
+
+STATISTIC(NumNoops , "Number of noops inserted");
+STATISTIC(NumStalls, "Number of pipeline stalls");
+
+static RegisterScheduler
+ VLIWScheduler("vliw-td", "VLIW scheduler",
+ createVLIWDAGScheduler);
+
+namespace {
+//===----------------------------------------------------------------------===//
+/// ScheduleDAGVLIW - The actual DFA list scheduler implementation. This
+/// supports / top-down scheduling.
+///
+class ScheduleDAGVLIW : public ScheduleDAGSDNodes {
+private:
+ /// AvailableQueue - The priority queue to use for the available SUnits.
+ ///
+ SchedulingPriorityQueue *AvailableQueue;
+
+ /// PendingQueue - This contains all of the instructions whose operands have
+ /// been issued, but their results are not ready yet (due to the latency of
+ /// the operation). Once the operands become available, the instruction is
+ /// added to the AvailableQueue.
+ std::vector<SUnit*> PendingQueue;
+
+ /// HazardRec - The hazard recognizer to use.
+ ScheduleHazardRecognizer *HazardRec;
+
+ /// AA - AliasAnalysis for making memory reference queries.
+ AliasAnalysis *AA;
+
+public:
+ ScheduleDAGVLIW(MachineFunction &mf,
+ AliasAnalysis *aa,
+ SchedulingPriorityQueue *availqueue)
+ : ScheduleDAGSDNodes(mf), AvailableQueue(availqueue), AA(aa) {
+
+ const TargetMachine &tm = mf.getTarget();
+ HazardRec = tm.getInstrInfo()->CreateTargetHazardRecognizer(&tm, this);
+ }
+
+ ~ScheduleDAGVLIW() {
+ delete HazardRec;
+ delete AvailableQueue;
+ }
+
+ void Schedule();
+
+private:
+ void releaseSucc(SUnit *SU, const SDep &D);
+ void releaseSuccessors(SUnit *SU);
+ void scheduleNodeTopDown(SUnit *SU, unsigned CurCycle);
+ void listScheduleTopDown();
+};
+} // end anonymous namespace
+
+/// Schedule - Schedule the DAG using list scheduling.
+void ScheduleDAGVLIW::Schedule() {
+ DEBUG(dbgs()
+ << "********** List Scheduling BB#" << BB->getNumber()
+ << " '" << BB->getName() << "' **********\n");
+
+ // Build the scheduling graph.
+ BuildSchedGraph(AA);
+
+ AvailableQueue->initNodes(SUnits);
+
+ listScheduleTopDown();
+
+ AvailableQueue->releaseState();
+}
+
+//===----------------------------------------------------------------------===//
+// Top-Down Scheduling
+//===----------------------------------------------------------------------===//
+
+/// releaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
+/// the PendingQueue if the count reaches zero. Also update its cycle bound.
+void ScheduleDAGVLIW::releaseSucc(SUnit *SU, const SDep &D) {
+ SUnit *SuccSU = D.getSUnit();
+
+#ifndef NDEBUG
+ if (SuccSU->NumPredsLeft == 0) {
+ dbgs() << "*** Scheduling failed! ***\n";
+ SuccSU->dump(this);
+ dbgs() << " has been released too many times!\n";
+ llvm_unreachable(0);
+ }
+#endif
+ --SuccSU->NumPredsLeft;
+
+ SuccSU->setDepthToAtLeast(SU->getDepth() + D.getLatency());
+
+ // If all the node's predecessors are scheduled, this node is ready
+ // to be scheduled. Ignore the special ExitSU node.
+ if (SuccSU->NumPredsLeft == 0 && SuccSU != &ExitSU) {
+ PendingQueue.push_back(SuccSU);
+ }
+}
+
+void ScheduleDAGVLIW::releaseSuccessors(SUnit *SU) {
+ // Top down: release successors.
+ for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+ I != E; ++I) {
+ assert(!I->isAssignedRegDep() &&
+ "The list-td scheduler doesn't yet support physreg dependencies!");
+
+ releaseSucc(SU, *I);
+ }
+}
+
+/// scheduleNodeTopDown - Add the node to the schedule. Decrement the pending
+/// count of its successors. If a successor pending count is zero, add it to
+/// the Available queue.
+void ScheduleDAGVLIW::scheduleNodeTopDown(SUnit *SU, unsigned CurCycle) {
+ DEBUG(dbgs() << "*** Scheduling [" << CurCycle << "]: ");
+ DEBUG(SU->dump(this));
+
+ Sequence.push_back(SU);
+ assert(CurCycle >= SU->getDepth() && "Node scheduled above its depth!");
+ SU->setDepthToAtLeast(CurCycle);
+
+ releaseSuccessors(SU);
+ SU->isScheduled = true;
+ AvailableQueue->scheduledNode(SU);
+}
+
+/// listScheduleTopDown - The main loop of list scheduling for top-down
+/// schedulers.
+void ScheduleDAGVLIW::listScheduleTopDown() {
+ unsigned CurCycle = 0;
+
+ // Release any successors of the special Entry node.
+ releaseSuccessors(&EntrySU);
+
+ // All leaves to AvailableQueue.
+ for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
+ // It is available if it has no predecessors.
+ if (SUnits[i].Preds.empty()) {
+ AvailableQueue->push(&SUnits[i]);
+ SUnits[i].isAvailable = true;
+ }
+ }
+
+ // While AvailableQueue is not empty, grab the node with the highest
+ // priority. If it is not ready put it back. Schedule the node.
+ std::vector<SUnit*> NotReady;
+ Sequence.reserve(SUnits.size());
+ while (!AvailableQueue->empty() || !PendingQueue.empty()) {
+ // Check to see if any of the pending instructions are ready to issue. If
+ // so, add them to the available queue.
+ for (unsigned i = 0, e = PendingQueue.size(); i != e; ++i) {
+ if (PendingQueue[i]->getDepth() == CurCycle) {
+ AvailableQueue->push(PendingQueue[i]);
+ PendingQueue[i]->isAvailable = true;
+ PendingQueue[i] = PendingQueue.back();
+ PendingQueue.pop_back();
+ --i; --e;
+ }
+ else {
+ assert(PendingQueue[i]->getDepth() > CurCycle && "Negative latency?");
+ }
+ }
+
+ // If there are no instructions available, don't try to issue anything, and
+ // don't advance the hazard recognizer.
+ if (AvailableQueue->empty()) {
+ // Reset DFA state.
+ AvailableQueue->scheduledNode(0);
+ ++CurCycle;
+ continue;
+ }
+
+ SUnit *FoundSUnit = 0;
+
+ bool HasNoopHazards = false;
+ while (!AvailableQueue->empty()) {
+ SUnit *CurSUnit = AvailableQueue->pop();
+
+ ScheduleHazardRecognizer::HazardType HT =
+ HazardRec->getHazardType(CurSUnit, 0/*no stalls*/);
+ if (HT == ScheduleHazardRecognizer::NoHazard) {
+ FoundSUnit = CurSUnit;
+ break;
+ }
+
+ // Remember if this is a noop hazard.
+ HasNoopHazards |= HT == ScheduleHazardRecognizer::NoopHazard;
+
+ NotReady.push_back(CurSUnit);
+ }
+
+ // Add the nodes that aren't ready back onto the available list.
+ if (!NotReady.empty()) {
+ AvailableQueue->push_all(NotReady);
+ NotReady.clear();
+ }
+
+ // If we found a node to schedule, do it now.
+ if (FoundSUnit) {
+ scheduleNodeTopDown(FoundSUnit, CurCycle);
+ HazardRec->EmitInstruction(FoundSUnit);
+
+ // If this is a pseudo-op node, we don't want to increment the current
+ // cycle.
+ if (FoundSUnit->Latency) // Don't increment CurCycle for pseudo-ops!
+ ++CurCycle;
+ } else if (!HasNoopHazards) {
+ // Otherwise, we have a pipeline stall, but no other problem, just advance
+ // the current cycle and try again.
+ DEBUG(dbgs() << "*** Advancing cycle, no work to do\n");
+ HazardRec->AdvanceCycle();
+ ++NumStalls;
+ ++CurCycle;
+ } else {
+ // Otherwise, we have no instructions to issue and we have instructions
+ // that will fault if we don't do this right. This is the case for
+ // processors without pipeline interlocks and other cases.
+ DEBUG(dbgs() << "*** Emitting noop\n");
+ HazardRec->EmitNoop();
+ Sequence.push_back(0); // NULL here means noop
+ ++NumNoops;
+ ++CurCycle;
+ }
+ }
+
+#ifndef NDEBUG
+ VerifyScheduledSequence(/*isBottomUp=*/false);
+#endif
+}
+
+//===----------------------------------------------------------------------===//
+// Public Constructor Functions
+//===----------------------------------------------------------------------===//
+
+/// createVLIWDAGScheduler - This creates a top-down list scheduler.
+ScheduleDAGSDNodes *
+llvm::createVLIWDAGScheduler(SelectionDAGISel *IS, CodeGenOpt::Level) {
+ return new ScheduleDAGVLIW(*IS->MF, IS->AA, new ResourcePriorityQueue(IS));
+}
--
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