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llvm-project/llvm/utils/TableGen/DFAPacketizerEmitter.cpp

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//===- DFAPacketizerEmitter.cpp - Packetization DFA for a VLIW machine ----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This class parses the Schedule.td file and produces an API that can be used
// to reason about whether an instruction can be added to a packet on a VLIW
// architecture. The class internally generates a deterministic finite
// automaton (DFA) that models all possible mappings of machine instructions
// to functional units as instructions are added to a packet.
//
//===----------------------------------------------------------------------===//
#include "CodeGenSchedule.h"
#include "CodeGenTarget.h"
#include "DFAEmitter.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/TableGen/Record.h"
#include "llvm/TableGen/TableGenBackend.h"
#include <cassert>
#include <cstdint>
#include <map>
#include <set>
#include <string>
#include <unordered_map>
#include <vector>
#define DEBUG_TYPE "dfa-emitter"
using namespace llvm;
// We use a uint64_t to represent a resource bitmask.
#define DFA_MAX_RESOURCES 64
namespace {
using ResourceVector = SmallVector<uint64_t, 4>;
struct ScheduleClass {
/// The parent itinerary index (processor model ID).
unsigned ItineraryID;
/// Index within this itinerary of the schedule class.
unsigned Idx;
/// The index within the uniqued set of required resources of Resources.
unsigned ResourcesIdx;
/// Conjunctive list of resource requirements:
/// {a|b, b|c} => (a OR b) AND (b or c).
/// Resources are unique across all itineraries.
ResourceVector Resources;
};
// Generates and prints out the DFA for resource tracking.
class DFAPacketizerEmitter {
private:
std::string TargetName;
RecordKeeper &Records;
UniqueVector<ResourceVector> UniqueResources;
std::vector<ScheduleClass> ScheduleClasses;
std::map<std::string, uint64_t> FUNameToBitsMap;
std::map<unsigned, uint64_t> ComboBitToBitsMap;
public:
DFAPacketizerEmitter(RecordKeeper &R);
// Construct a map of function unit names to bits.
int collectAllFuncUnits(
ArrayRef<const CodeGenProcModel *> ProcModels);
// Construct a map from a combo function unit bit to the bits of all included
// functional units.
int collectAllComboFuncs(ArrayRef<Record *> ComboFuncList);
ResourceVector getResourcesForItinerary(Record *Itinerary);
void createScheduleClasses(unsigned ItineraryIdx, const RecVec &Itineraries);
// Emit code for a subset of itineraries.
void emitForItineraries(raw_ostream &OS,
std::vector<const CodeGenProcModel *> &ProcItinList,
std::string DFAName);
void run(raw_ostream &OS);
};
} // end anonymous namespace
DFAPacketizerEmitter::DFAPacketizerEmitter(RecordKeeper &R)
: TargetName(std::string(CodeGenTarget(R).getName())), Records(R) {}
int DFAPacketizerEmitter::collectAllFuncUnits(
ArrayRef<const CodeGenProcModel *> ProcModels) {
LLVM_DEBUG(dbgs() << "-------------------------------------------------------"
"----------------------\n");
LLVM_DEBUG(dbgs() << "collectAllFuncUnits");
LLVM_DEBUG(dbgs() << " (" << ProcModels.size() << " itineraries)\n");
std::set<Record *> ProcItinList;
for (const CodeGenProcModel *Model : ProcModels)
ProcItinList.insert(Model->ItinsDef);
int totalFUs = 0;
// Parse functional units for all the itineraries.
for (Record *Proc : ProcItinList) {
std::vector<Record *> FUs = Proc->getValueAsListOfDefs("FU");
LLVM_DEBUG(dbgs() << " FU:"
<< " (" << FUs.size() << " FUs) " << Proc->getName());
// Convert macros to bits for each stage.
unsigned numFUs = FUs.size();
for (unsigned j = 0; j < numFUs; ++j) {
assert((j < DFA_MAX_RESOURCES) &&
"Exceeded maximum number of representable resources");
uint64_t FuncResources = 1ULL << j;
FUNameToBitsMap[std::string(FUs[j]->getName())] = FuncResources;
LLVM_DEBUG(dbgs() << " " << FUs[j]->getName() << ":0x"
<< Twine::utohexstr(FuncResources));
}
totalFUs += numFUs;
LLVM_DEBUG(dbgs() << "\n");
}
return totalFUs;
}
int DFAPacketizerEmitter::collectAllComboFuncs(ArrayRef<Record *> ComboFuncList) {
LLVM_DEBUG(dbgs() << "-------------------------------------------------------"
"----------------------\n");
LLVM_DEBUG(dbgs() << "collectAllComboFuncs");
LLVM_DEBUG(dbgs() << " (" << ComboFuncList.size() << " sets)\n");
int numCombos = 0;
for (unsigned i = 0, N = ComboFuncList.size(); i < N; ++i) {
Record *Func = ComboFuncList[i];
std::vector<Record *> FUs = Func->getValueAsListOfDefs("CFD");
LLVM_DEBUG(dbgs() << " CFD:" << i << " (" << FUs.size() << " combo FUs) "
<< Func->getName() << "\n");
// Convert macros to bits for each stage.
for (unsigned j = 0, N = FUs.size(); j < N; ++j) {
assert((j < DFA_MAX_RESOURCES) &&
"Exceeded maximum number of DFA resources");
Record *FuncData = FUs[j];
Record *ComboFunc = FuncData->getValueAsDef("TheComboFunc");
const std::vector<Record *> &FuncList =
FuncData->getValueAsListOfDefs("FuncList");
const std::string &ComboFuncName = std::string(ComboFunc->getName());
uint64_t ComboBit = FUNameToBitsMap[ComboFuncName];
uint64_t ComboResources = ComboBit;
LLVM_DEBUG(dbgs() << " combo: " << ComboFuncName << ":0x"
<< Twine::utohexstr(ComboResources) << "\n");
for (auto *K : FuncList) {
std::string FuncName = std::string(K->getName());
uint64_t FuncResources = FUNameToBitsMap[FuncName];
LLVM_DEBUG(dbgs() << " " << FuncName << ":0x"
<< Twine::utohexstr(FuncResources) << "\n");
ComboResources |= FuncResources;
}
ComboBitToBitsMap[ComboBit] = ComboResources;
numCombos++;
LLVM_DEBUG(dbgs() << " => combo bits: " << ComboFuncName << ":0x"
<< Twine::utohexstr(ComboBit) << " = 0x"
<< Twine::utohexstr(ComboResources) << "\n");
}
}
return numCombos;
}
ResourceVector
DFAPacketizerEmitter::getResourcesForItinerary(Record *Itinerary) {
ResourceVector Resources;
assert(Itinerary);
for (Record *StageDef : Itinerary->getValueAsListOfDefs("Stages")) {
uint64_t StageResources = 0;
for (Record *Unit : StageDef->getValueAsListOfDefs("Units")) {
StageResources |= FUNameToBitsMap[std::string(Unit->getName())];
}
if (StageResources != 0)
Resources.push_back(StageResources);
}
return Resources;
}
void DFAPacketizerEmitter::createScheduleClasses(unsigned ItineraryIdx,
const RecVec &Itineraries) {
unsigned Idx = 0;
for (Record *Itinerary : Itineraries) {
if (!Itinerary) {
ScheduleClasses.push_back({ItineraryIdx, Idx++, 0, ResourceVector{}});
continue;
}
ResourceVector Resources = getResourcesForItinerary(Itinerary);
ScheduleClasses.push_back(
{ItineraryIdx, Idx++, UniqueResources.insert(Resources), Resources});
}
}
//
// Run the worklist algorithm to generate the DFA.
//
void DFAPacketizerEmitter::run(raw_ostream &OS) {
OS << "\n"
<< "#include \"llvm/CodeGen/DFAPacketizer.h\"\n";
OS << "namespace llvm {\n";
CodeGenTarget CGT(Records);
CodeGenSchedModels CGS(Records, CGT);
std::unordered_map<std::string, std::vector<const CodeGenProcModel *>>
ItinsByNamespace;
for (const CodeGenProcModel &ProcModel : CGS.procModels()) {
if (ProcModel.hasItineraries()) {
auto NS = ProcModel.ItinsDef->getValueAsString("PacketizerNamespace");
ItinsByNamespace[std::string(NS)].push_back(&ProcModel);
}
}
for (auto &KV : ItinsByNamespace)
emitForItineraries(OS, KV.second, KV.first);
OS << "} // end namespace llvm\n";
}
void DFAPacketizerEmitter::emitForItineraries(
raw_ostream &OS, std::vector<const CodeGenProcModel *> &ProcModels,
std::string DFAName) {
OS << "} // end namespace llvm\n\n";
OS << "namespace {\n";
collectAllFuncUnits(ProcModels);
collectAllComboFuncs(Records.getAllDerivedDefinitions("ComboFuncUnits"));
// Collect the itineraries.
DenseMap<const CodeGenProcModel *, unsigned> ProcModelStartIdx;
for (const CodeGenProcModel *Model : ProcModels) {
assert(Model->hasItineraries());
ProcModelStartIdx[Model] = ScheduleClasses.size();
createScheduleClasses(Model->Index, Model->ItinDefList);
}
// Output the mapping from ScheduleClass to ResourcesIdx.
unsigned Idx = 0;
OS << "constexpr unsigned " << TargetName << DFAName
<< "ResourceIndices[] = {";
for (const ScheduleClass &SC : ScheduleClasses) {
if (Idx++ % 32 == 0)
OS << "\n ";
OS << SC.ResourcesIdx << ", ";
}
OS << "\n};\n\n";
// And the mapping from Itinerary index into the previous table.
OS << "constexpr unsigned " << TargetName << DFAName
<< "ProcResourceIndexStart[] = {\n";
OS << " 0, // NoSchedModel\n";
for (const CodeGenProcModel *Model : ProcModels) {
OS << " " << ProcModelStartIdx[Model] << ", // " << Model->ModelName
<< "\n";
}
OS << " " << ScheduleClasses.size() << "\n};\n\n";
// The type of a state in the nondeterministic automaton we're defining.
using NfaStateTy = uint64_t;
// Given a resource state, return all resource states by applying
// InsnClass.
auto applyInsnClass = [&](const ResourceVector &InsnClass,
NfaStateTy State) -> std::deque<NfaStateTy> {
std::deque<NfaStateTy> V(1, State);
// Apply every stage in the class individually.
for (NfaStateTy Stage : InsnClass) {
// Apply this stage to every existing member of V in turn.
size_t Sz = V.size();
for (unsigned I = 0; I < Sz; ++I) {
NfaStateTy S = V.front();
V.pop_front();
// For this stage, state combination, try all possible resources.
for (unsigned J = 0; J < DFA_MAX_RESOURCES; ++J) {
NfaStateTy ResourceMask = 1ULL << J;
if ((ResourceMask & Stage) == 0)
// This resource isn't required by this stage.
continue;
NfaStateTy Combo = ComboBitToBitsMap[ResourceMask];
if (Combo && ((~S & Combo) != Combo))
// This combo units bits are not available.
continue;
NfaStateTy ResultingResourceState = S | ResourceMask | Combo;
if (ResultingResourceState == S)
continue;
V.push_back(ResultingResourceState);
}
}
}
return V;
};
// Given a resource state, return a quick (conservative) guess as to whether
// InsnClass can be applied. This is a filter for the more heavyweight
// applyInsnClass.
auto canApplyInsnClass = [](const ResourceVector &InsnClass,
NfaStateTy State) -> bool {
for (NfaStateTy Resources : InsnClass) {
if ((State | Resources) == State)
return false;
}
return true;
};
DfaEmitter Emitter;
std::deque<NfaStateTy> Worklist(1, 0);
std::set<NfaStateTy> SeenStates;
SeenStates.insert(Worklist.front());
while (!Worklist.empty()) {
NfaStateTy State = Worklist.front();
Worklist.pop_front();
for (const ResourceVector &Resources : UniqueResources) {
if (!canApplyInsnClass(Resources, State))
continue;
unsigned ResourcesID = UniqueResources.idFor(Resources);
for (uint64_t NewState : applyInsnClass(Resources, State)) {
if (SeenStates.emplace(NewState).second)
Worklist.emplace_back(NewState);
Emitter.addTransition(State, NewState, ResourcesID);
}
}
}
std::string TargetAndDFAName = TargetName + DFAName;
Emitter.emit(TargetAndDFAName, OS);
OS << "} // end anonymous namespace\n\n";
std::string SubTargetClassName = TargetName + "GenSubtargetInfo";
OS << "namespace llvm {\n";
OS << "DFAPacketizer *" << SubTargetClassName << "::"
<< "create" << DFAName
<< "DFAPacketizer(const InstrItineraryData *IID) const {\n"
<< " static Automaton<uint64_t> A(ArrayRef<" << TargetAndDFAName
<< "Transition>(" << TargetAndDFAName << "Transitions), "
<< TargetAndDFAName << "TransitionInfo);\n"
<< " unsigned ProcResIdxStart = " << TargetAndDFAName
<< "ProcResourceIndexStart[IID->SchedModel.ProcID];\n"
<< " unsigned ProcResIdxNum = " << TargetAndDFAName
<< "ProcResourceIndexStart[IID->SchedModel.ProcID + 1] - "
"ProcResIdxStart;\n"
<< " return new DFAPacketizer(IID, A, {&" << TargetAndDFAName
<< "ResourceIndices[ProcResIdxStart], ProcResIdxNum});\n"
<< "\n}\n\n";
}
namespace llvm {
void EmitDFAPacketizer(RecordKeeper &RK, raw_ostream &OS) {
emitSourceFileHeader("Target DFA Packetizer Tables", OS);
DFAPacketizerEmitter(RK).run(OS);
}
} // end namespace llvm
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