1 files changed, 243 insertions, 0 deletions
diff --git a/lib/CodeGen/ScoreboardHazardRecognizer.cpp b/lib/CodeGen/ScoreboardHazardRecognizer.cpp
new file mode 100644
index 0000000..e6d7ded
--- /dev/null
+++ b/lib/CodeGen/ScoreboardHazardRecognizer.cpp
@@ -0,0 +1,243 @@
+//===----- ScoreboardHazardRecognizer.cpp - Scheduler Support -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the ScoreboardHazardRecognizer class, which
+// encapsultes hazard-avoidance heuristics for scheduling, based on the
+// scheduling itineraries specified for the target.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE ::llvm::ScoreboardHazardRecognizer::DebugType
+#include "llvm/CodeGen/ScoreboardHazardRecognizer.h"
+#include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetInstrItineraries.h"
+
+using namespace llvm;
+
+#ifndef NDEBUG
+const char *ScoreboardHazardRecognizer::DebugType = "";
+#endif
+
+ScoreboardHazardRecognizer::
+ScoreboardHazardRecognizer(const InstrItineraryData *II,
+                           const ScheduleDAG *SchedDAG,
+                           const char *ParentDebugType) :
+  ScheduleHazardRecognizer(), ItinData(II), DAG(SchedDAG), IssueWidth(0),
+  IssueCount(0) {
+
+#ifndef NDEBUG
+  DebugType = ParentDebugType;
+#endif
+
+  // Determine the maximum depth of any itinerary. This determines the
+  // depth of the scoreboard. We always make the scoreboard at least 1
+  // cycle deep to avoid dealing with the boundary condition.
+  unsigned ScoreboardDepth = 1;
+  if (ItinData && !ItinData->isEmpty()) {
+    IssueWidth = ItinData->IssueWidth;
+
+    for (unsigned idx = 0; ; ++idx) {
+      if (ItinData->isEndMarker(idx))
+        break;
+
+      const InstrStage *IS = ItinData->beginStage(idx);
+      const InstrStage *E = ItinData->endStage(idx);
+      unsigned CurCycle = 0;
+      unsigned ItinDepth = 0;
+      for (; IS != E; ++IS) {
+        unsigned StageDepth = CurCycle + IS->getCycles();
+        if (ItinDepth < StageDepth) ItinDepth = StageDepth;
+        CurCycle += IS->getNextCycles();
+      }
+
+      // Find the next power-of-2 >= ItinDepth
+      while (ItinDepth > ScoreboardDepth) {
+        ScoreboardDepth *= 2;
+      }
+    }
+    MaxLookAhead = ScoreboardDepth;
+  }
+
+  ReservedScoreboard.reset(ScoreboardDepth);
+  RequiredScoreboard.reset(ScoreboardDepth);
+
+  DEBUG(dbgs() << "Using scoreboard hazard recognizer: Depth = "
+               << ScoreboardDepth << '\n');
+}
+
+void ScoreboardHazardRecognizer::Reset() {
+  IssueCount = 0;
+  RequiredScoreboard.reset();
+  ReservedScoreboard.reset();
+}
+
+void ScoreboardHazardRecognizer::Scoreboard::dump() const {
+  dbgs() << "Scoreboard:\n";
+
+  unsigned last = Depth - 1;
+  while ((last > 0) && ((*this)[last] == 0))
+    last--;
+
+  for (unsigned i = 0; i <= last; i++) {
+    unsigned FUs = (*this)[i];
+    dbgs() << "\t";
+    for (int j = 31; j >= 0; j--)
+      dbgs() << ((FUs & (1 << j)) ? '1' : '0');
+    dbgs() << '\n';
+  }
+}
+
+bool ScoreboardHazardRecognizer::atIssueLimit() const {
+  if (IssueWidth == 0)
+    return false;
+
+  return IssueCount == IssueWidth;
+}
+
+ScheduleHazardRecognizer::HazardType
+ScoreboardHazardRecognizer::getHazardType(SUnit *SU, int Stalls) {
+  if (!ItinData || ItinData->isEmpty())
+    return NoHazard;
+
+  // Note that stalls will be negative for bottom-up scheduling.
+  int cycle = Stalls;
+
+  // Use the itinerary for the underlying instruction to check for
+  // free FU's in the scoreboard at the appropriate future cycles.
+
+  const TargetInstrDesc *TID = DAG->getInstrDesc(SU);
+  if (TID == NULL) {
+    // Don't check hazards for non-machineinstr Nodes.
+    return NoHazard;
+  }
+  unsigned idx = TID->getSchedClass();
+  for (const InstrStage *IS = ItinData->beginStage(idx),
+         *E = ItinData->endStage(idx); IS != E; ++IS) {
+    // We must find one of the stage's units free for every cycle the
+    // stage is occupied. FIXME it would be more accurate to find the
+    // same unit free in all the cycles.
+    for (unsigned int i = 0; i < IS->getCycles(); ++i) {
+      int StageCycle = cycle + (int)i;
+      if (StageCycle < 0)
+        continue;
+
+      if (StageCycle >= (int)RequiredScoreboard.getDepth()) {
+        assert((StageCycle - Stalls) < (int)RequiredScoreboard.getDepth() &&
+               "Scoreboard depth exceeded!");
+        // This stage was stalled beyond pipeline depth, so cannot conflict.
+        break;
+      }
+
+      unsigned freeUnits = IS->getUnits();
+      switch (IS->getReservationKind()) {
+      default:
+       assert(0 && "Invalid FU reservation");
+      case InstrStage::Required:
+        // Required FUs conflict with both reserved and required ones
+        freeUnits &= ~ReservedScoreboard[StageCycle];
+        // FALLTHROUGH
+      case InstrStage::Reserved:
+        // Reserved FUs can conflict only with required ones.
+        freeUnits &= ~RequiredScoreboard[StageCycle];
+        break;
+      }
+
+      if (!freeUnits) {
+        DEBUG(dbgs() << "*** Hazard in cycle " << (cycle + i) << ", ");
+        DEBUG(dbgs() << "SU(" << SU->NodeNum << "): ");
+        DEBUG(DAG->dumpNode(SU));
+        return Hazard;
+      }
+    }
+
+    // Advance the cycle to the next stage.
+    cycle += IS->getNextCycles();
+  }
+
+  return NoHazard;
+}
+
+void ScoreboardHazardRecognizer::EmitInstruction(SUnit *SU) {
+  if (!ItinData || ItinData->isEmpty())
+    return;
+
+  // Use the itinerary for the underlying instruction to reserve FU's
+  // in the scoreboard at the appropriate future cycles.
+  const TargetInstrDesc *TID = DAG->getInstrDesc(SU);
+  assert(TID && "The scheduler must filter non-machineinstrs");
+  if (DAG->TII->isZeroCost(TID->Opcode))
+    return;
+
+  ++IssueCount;
+
+  unsigned cycle = 0;
+
+  unsigned idx = TID->getSchedClass();
+  for (const InstrStage *IS = ItinData->beginStage(idx),
+         *E = ItinData->endStage(idx); IS != E; ++IS) {
+    // We must reserve one of the stage's units for every cycle the
+    // stage is occupied. FIXME it would be more accurate to reserve
+    // the same unit free in all the cycles.
+    for (unsigned int i = 0; i < IS->getCycles(); ++i) {
+      assert(((cycle + i) < RequiredScoreboard.getDepth()) &&
+             "Scoreboard depth exceeded!");
+
+      unsigned freeUnits = IS->getUnits();
+      switch (IS->getReservationKind()) {
+      default:
+       assert(0 && "Invalid FU reservation");
+      case InstrStage::Required:
+        // Required FUs conflict with both reserved and required ones
+        freeUnits &= ~ReservedScoreboard[cycle + i];
+        // FALLTHROUGH
+      case InstrStage::Reserved:
+        // Reserved FUs can conflict only with required ones.
+        freeUnits &= ~RequiredScoreboard[cycle + i];
+        break;
+      }
+
+      // reduce to a single unit
+      unsigned freeUnit = 0;
+      do {
+        freeUnit = freeUnits;
+        freeUnits = freeUnit & (freeUnit - 1);
+      } while (freeUnits);
+
+      assert(freeUnit && "No function unit available!");
+      if (IS->getReservationKind() == InstrStage::Required)
+        RequiredScoreboard[cycle + i] |= freeUnit;
+      else
+        ReservedScoreboard[cycle + i] |= freeUnit;
+    }
+
+    // Advance the cycle to the next stage.
+    cycle += IS->getNextCycles();
+  }
+
+  DEBUG(ReservedScoreboard.dump());
+  DEBUG(RequiredScoreboard.dump());
+}
+
+void ScoreboardHazardRecognizer::AdvanceCycle() {
+  IssueCount = 0;
+  ReservedScoreboard[0] = 0; ReservedScoreboard.advance();
+  RequiredScoreboard[0] = 0; RequiredScoreboard.advance();
+}
+
+void ScoreboardHazardRecognizer::RecedeCycle() {
+  IssueCount = 0;
+  ReservedScoreboard[ReservedScoreboard.getDepth()-1] = 0;
+  ReservedScoreboard.recede();
+  RequiredScoreboard[RequiredScoreboard.getDepth()-1] = 0;
+  RequiredScoreboard.recede();
+}