//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "sched-hazard"
#include "llvm/CodeGen/ScoreboardHazardRecognizer.h"
#include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/MC/MCInstrItineraries.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetInstrItineraries.h"
+#include "llvm/Target/TargetInstrInfo.h"
using namespace llvm;
+#define DEBUG_TYPE ::llvm::ScoreboardHazardRecognizer::DebugType
+
+#ifndef NDEBUG
+const char *ScoreboardHazardRecognizer::DebugType = "";
+#endif
+
ScoreboardHazardRecognizer::
-ScoreboardHazardRecognizer(const InstrItineraryData *LItinData) :
- ScheduleHazardRecognizer(), ItinData(LItinData) {
- // 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.
+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()) {
for (unsigned idx = 0; ; ++idx) {
const InstrStage *IS = ItinData->beginStage(idx);
const InstrStage *E = ItinData->endStage(idx);
+ unsigned CurCycle = 0;
unsigned ItinDepth = 0;
- for (; IS != E; ++IS)
- ItinDepth += IS->getCycles();
+ 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;
+ // Don't set MaxLookAhead until we find at least one nonzero stage.
+ // This way, an itinerary with no stages has MaxLookAhead==0, which
+ // completely bypasses the scoreboard hazard logic.
+ MaxLookAhead = ScoreboardDepth;
}
}
}
ReservedScoreboard.reset(ScoreboardDepth);
RequiredScoreboard.reset(ScoreboardDepth);
- DEBUG(dbgs() << "Using scoreboard hazard recognizer: Depth = "
- << ScoreboardDepth << '\n');
+ // If MaxLookAhead is not set above, then we are not enabled.
+ if (!isEnabled())
+ DEBUG(dbgs() << "Disabled scoreboard hazard recognizer\n");
+ else {
+ // A nonempty itinerary must have a SchedModel.
+ IssueWidth = ItinData->SchedModel.IssueWidth;
+ DEBUG(dbgs() << "Using scoreboard hazard recognizer: Depth = "
+ << ScoreboardDepth << '\n');
+ }
}
void ScoreboardHazardRecognizer::Reset() {
+ IssueCount = 0;
RequiredScoreboard.reset();
ReservedScoreboard.reset();
}
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void ScoreboardHazardRecognizer::Scoreboard::dump() const {
dbgs() << "Scoreboard:\n";
dbgs() << '\n';
}
}
+#endif
+
+bool ScoreboardHazardRecognizer::atIssueLimit() const {
+ if (IssueWidth == 0)
+ return false;
+
+ return IssueCount == IssueWidth;
+}
ScheduleHazardRecognizer::HazardType
-ScoreboardHazardRecognizer::getHazardType(SUnit *SU) {
+ScoreboardHazardRecognizer::getHazardType(SUnit *SU, int Stalls) {
if (!ItinData || ItinData->isEmpty())
return NoHazard;
- unsigned cycle = 0;
+ // 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.
- unsigned idx = SU->getInstr()->getDesc().getSchedClass();
+
+ const MCInstrDesc *MCID = DAG->getInstrDesc(SU);
+ if (!MCID) {
+ // Don't check hazards for non-machineinstr Nodes.
+ return NoHazard;
+ }
+ unsigned idx = MCID->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) {
- assert(((cycle + i) < RequiredScoreboard.getDepth()) &&
- "Scoreboard depth exceeded!");
+ 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[cycle + i];
+ freeUnits &= ~ReservedScoreboard[StageCycle];
// FALLTHROUGH
case InstrStage::Reserved:
// Reserved FUs can conflict only with required ones.
- freeUnits &= ~RequiredScoreboard[cycle + i];
+ freeUnits &= ~RequiredScoreboard[StageCycle];
break;
}
if (!freeUnits) {
- DEBUG(dbgs() << "*** Hazard in cycle " << (cycle + i) << ", ");
+ DEBUG(dbgs() << "*** Hazard in cycle +" << StageCycle << ", ");
DEBUG(dbgs() << "SU(" << SU->NodeNum << "): ");
- DEBUG(SU->getInstr()->dump());
+ DEBUG(DAG->dumpNode(SU));
return Hazard;
}
}
if (!ItinData || ItinData->isEmpty())
return;
- unsigned cycle = 0;
-
// Use the itinerary for the underlying instruction to reserve FU's
// in the scoreboard at the appropriate future cycles.
- unsigned idx = SU->getInstr()->getDesc().getSchedClass();
+ const MCInstrDesc *MCID = DAG->getInstrDesc(SU);
+ assert(MCID && "The scheduler must filter non-machineinstrs");
+ if (DAG->TII->isZeroCost(MCID->Opcode))
+ return;
+
+ ++IssueCount;
+
+ unsigned cycle = 0;
+
+ unsigned idx = MCID->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
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];
freeUnits = freeUnit & (freeUnit - 1);
} while (freeUnits);
- assert(freeUnit && "No function unit available!");
if (IS->getReservationKind() == InstrStage::Required)
RequiredScoreboard[cycle + i] |= freeUnit;
else
}
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;
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