1 //===----- ExactHazardRecognizer.cpp - hazard recognizer -------- ---------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This implements a a hazard recognizer using the instructions itineraries
11 // defined for the current target.
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "exact-hazards"
16 #include "ExactHazardRecognizer.h"
17 #include "llvm/CodeGen/ScheduleHazardRecognizer.h"
18 #include "llvm/Support/Debug.h"
19 #include "llvm/Support/ErrorHandling.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include "llvm/Target/TargetInstrItineraries.h"
25 ExactHazardRecognizer::ExactHazardRecognizer(const InstrItineraryData &LItinData) :
26 ScheduleHazardRecognizer(), ItinData(LItinData)
28 // Determine the maximum depth of any itinerary. This determines the
29 // depth of the scoreboard. We always make the scoreboard at least 1
30 // cycle deep to avoid dealing with the boundary condition.
32 if (!ItinData.isEmpty()) {
33 for (unsigned idx = 0; ; ++idx) {
34 // If the begin stage of an itinerary has 0 cycles and units,
35 // then we have reached the end of the itineraries.
36 const InstrStage *IS = ItinData.beginStage(idx);
37 const InstrStage *E = ItinData.endStage(idx);
38 if ((IS->getCycles() == 0) && (IS->getUnits() == 0))
41 unsigned ItinDepth = 0;
43 ItinDepth += IS->getCycles();
45 ScoreboardDepth = std::max(ScoreboardDepth, ItinDepth);
49 Scoreboard = new unsigned[ScoreboardDepth];
52 DEBUG(errs() << "Using exact hazard recognizer: ScoreboardDepth = "
53 << ScoreboardDepth << '\n');
56 ExactHazardRecognizer::~ExactHazardRecognizer() {
60 void ExactHazardRecognizer::Reset() {
61 memset(Scoreboard, 0, ScoreboardDepth * sizeof(unsigned));
65 unsigned ExactHazardRecognizer::getFutureIndex(unsigned offset) {
66 return (ScoreboardHead + offset) % ScoreboardDepth;
69 void ExactHazardRecognizer::dumpScoreboard() {
70 errs() << "Scoreboard:\n";
72 unsigned last = ScoreboardDepth - 1;
73 while ((last > 0) && (Scoreboard[getFutureIndex(last)] == 0))
76 for (unsigned i = 0; i <= last; i++) {
77 unsigned FUs = Scoreboard[getFutureIndex(i)];
79 for (int j = 31; j >= 0; j--)
80 errs() << ((FUs & (1 << j)) ? '1' : '0');
85 ExactHazardRecognizer::HazardType ExactHazardRecognizer::getHazardType(SUnit *SU) {
86 if (ItinData.isEmpty())
91 // Use the itinerary for the underlying instruction to check for
92 // free FU's in the scoreboard at the appropriate future cycles.
93 unsigned idx = SU->getInstr()->getDesc().getSchedClass();
94 for (const InstrStage *IS = ItinData.beginStage(idx),
95 *E = ItinData.endStage(idx); IS != E; ++IS) {
96 // We must find one of the stage's units free for every cycle the
97 // stage is occupied. FIXME it would be more accurate to find the
98 // same unit free in all the cycles.
99 for (unsigned int i = 0; i < IS->getCycles(); ++i) {
100 assert(((cycle + i) < ScoreboardDepth) &&
101 "Scoreboard depth exceeded!");
103 unsigned index = getFutureIndex(cycle + i);
104 unsigned freeUnits = IS->getUnits() & ~Scoreboard[index];
106 DEBUG(errs() << "*** Hazard in cycle " << (cycle + i) << ", ");
107 DEBUG(errs() << "SU(" << SU->NodeNum << "): ");
108 DEBUG(SU->getInstr()->dump());
113 // Advance the cycle to the next stage.
114 cycle += IS->getNextCycles();
120 void ExactHazardRecognizer::EmitInstruction(SUnit *SU) {
121 if (ItinData.isEmpty())
126 // Use the itinerary for the underlying instruction to reserve FU's
127 // in the scoreboard at the appropriate future cycles.
128 unsigned idx = SU->getInstr()->getDesc().getSchedClass();
129 for (const InstrStage *IS = ItinData.beginStage(idx),
130 *E = ItinData.endStage(idx); IS != E; ++IS) {
131 // We must reserve one of the stage's units for every cycle the
132 // stage is occupied. FIXME it would be more accurate to reserve
133 // the same unit free in all the cycles.
134 for (unsigned int i = 0; i < IS->getCycles(); ++i) {
135 assert(((cycle + i) < ScoreboardDepth) &&
136 "Scoreboard depth exceeded!");
138 unsigned index = getFutureIndex(cycle + i);
139 unsigned freeUnits = IS->getUnits() & ~Scoreboard[index];
141 // reduce to a single unit
142 unsigned freeUnit = 0;
144 freeUnit = freeUnits;
145 freeUnits = freeUnit & (freeUnit - 1);
148 assert(freeUnit && "No function unit available!");
149 Scoreboard[index] |= freeUnit;
152 // Advance the cycle to the next stage.
153 cycle += IS->getNextCycles();
156 DEBUG(dumpScoreboard());
159 void ExactHazardRecognizer::AdvanceCycle() {
160 Scoreboard[ScoreboardHead] = 0;
161 ScoreboardHead = getFutureIndex(1);