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//===----- PostRAHazardRecognizer.cpp - hazard recognizer -------- ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This implements a hazard recognizer using the instructions itineraries
// defined for the current target.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "post-RA-sched"
#include "llvm/CodeGen/PostRAHazardRecognizer.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/TargetInstrItineraries.h"
using namespace llvm;
PostRAHazardRecognizer::
PostRAHazardRecognizer(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.
unsigned ScoreboardDepth = 1;
if (!ItinData.isEmpty()) {
for (unsigned idx = 0; ; ++idx) {
if (ItinData.isEndMarker(idx))
break;
const InstrStage *IS = ItinData.beginStage(idx);
const InstrStage *E = ItinData.endStage(idx);
unsigned ItinDepth = 0;
for (; IS != E; ++IS)
ItinDepth += IS->getCycles();
ScoreboardDepth = std::max(ScoreboardDepth, ItinDepth);
}
}
ReservedScoreboard.reset(ScoreboardDepth);
RequiredScoreboard.reset(ScoreboardDepth);
DEBUG(dbgs() << "Using post-ra hazard recognizer: ScoreboardDepth = "
<< ScoreboardDepth << '\n');
}
void PostRAHazardRecognizer::Reset() {
RequiredScoreboard.reset();
ReservedScoreboard.reset();
}
void PostRAHazardRecognizer::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';
}
}
ScheduleHazardRecognizer::HazardType
PostRAHazardRecognizer::getHazardType(SUnit *SU) {
if (ItinData.isEmpty())
return NoHazard;
unsigned cycle = 0;
// 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();
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!");
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;
}
if (!freeUnits) {
DEBUG(dbgs() << "*** Hazard in cycle " << (cycle + i) << ", ");
DEBUG(dbgs() << "SU(" << SU->NodeNum << "): ");
DEBUG(SU->getInstr()->dump());
return Hazard;
}
}
// Advance the cycle to the next stage.
cycle += IS->getNextCycles();
}
return NoHazard;
}
void PostRAHazardRecognizer::EmitInstruction(SUnit *SU) {
if (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();
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 PostRAHazardRecognizer::AdvanceCycle() {
ReservedScoreboard[0] = 0; ReservedScoreboard.advance();
RequiredScoreboard[0] = 0; RequiredScoreboard.advance();
}
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