llvm-6502/lib/CodeGen/ExactHazardRecognizer.cpp

150 lines
4.6 KiB
C++

//===----- ExactHazardRecognizer.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 a hazard recognizer using the instructions itineraries
// defined for the current target.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "exact-hazards"
#include "ExactHazardRecognizer.h"
#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Target/TargetInstrItineraries.h"
namespace llvm {
ExactHazardRecognizer::ExactHazardRecognizer(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.
ScoreboardDepth = 1;
if (!ItinData.isEmpty()) {
for (unsigned idx = 0; ; ++idx) {
// If the begin stage of an itinerary has 0 cycles and units,
// then we have reached the end of the itineraries.
const InstrStage *IS = ItinData.begin(idx), *E = ItinData.end(idx);
if ((IS->Cycles == 0) && (IS->Units == 0))
break;
unsigned ItinDepth = 0;
for (; IS != E; ++IS)
ItinDepth += IS->Cycles;
ScoreboardDepth = std::max(ScoreboardDepth, ItinDepth);
}
}
Scoreboard = new unsigned[ScoreboardDepth];
ScoreboardHead = 0;
DOUT << "Using exact hazard recognizer: ScoreboardDepth = "
<< ScoreboardDepth << '\n';
}
ExactHazardRecognizer::~ExactHazardRecognizer() {
delete Scoreboard;
}
void ExactHazardRecognizer::Reset() {
memset(Scoreboard, 0, ScoreboardDepth * sizeof(unsigned));
ScoreboardHead = 0;
}
unsigned ExactHazardRecognizer::getFutureIndex(unsigned offset) {
return (ScoreboardHead + offset) % ScoreboardDepth;
}
void ExactHazardRecognizer::dumpScoreboard() {
DOUT << "Scoreboard:\n";
unsigned last = ScoreboardDepth - 1;
while ((last > 0) && (Scoreboard[getFutureIndex(last)] == 0))
last--;
for (unsigned i = 0; i <= last; i++) {
unsigned FUs = Scoreboard[getFutureIndex(i)];
DOUT << "\t";
for (int j = 31; j >= 0; j--)
DOUT << ((FUs & (1 << j)) ? '1' : '0');
DOUT << '\n';
}
}
ExactHazardRecognizer::HazardType ExactHazardRecognizer::getHazardType(SUnit *SU) {
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.begin(idx), *E = ItinData.end(idx);
IS != E; ++IS) {
// We must find one of the stage's units free for every cycle the
// stage is occupied.
for (unsigned int i = 0; i < IS->Cycles; ++i) {
assert((cycle < ScoreboardDepth) && "Scoreboard depth exceeded!");
unsigned index = getFutureIndex(cycle);
unsigned freeUnits = IS->Units & ~Scoreboard[index];
if (!freeUnits) {
DOUT << "*** Hazard in cycle " << cycle << ", ";
DOUT << "SU(" << SU->NodeNum << "): ";
DEBUG(SU->getInstr()->dump());
return Hazard;
}
++cycle;
}
}
return NoHazard;
}
void ExactHazardRecognizer::EmitInstruction(SUnit *SU) {
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.begin(idx), *E = ItinData.end(idx);
IS != E; ++IS) {
// We must reserve one of the stage's units for every cycle the
// stage is occupied.
for (unsigned int i = 0; i < IS->Cycles; ++i) {
assert((cycle < ScoreboardDepth) && "Scoreboard depth exceeded!");
unsigned index = getFutureIndex(cycle);
unsigned freeUnits = IS->Units & ~Scoreboard[index];
// reduce to a single unit
unsigned freeUnit = 0;
do {
freeUnit = freeUnits;
freeUnits = freeUnit & (freeUnit - 1);
} while (freeUnits);
assert(freeUnit && "No function unit available!");
Scoreboard[index] |= freeUnit;
++cycle;
}
}
DEBUG(dumpScoreboard());
}
void ExactHazardRecognizer::AdvanceCycle() {
Scoreboard[ScoreboardHead] = 0;
ScoreboardHead = getFutureIndex(1);
}
} /* namespace llvm */