//===- CodeGenRegisters.cpp - Register and RegisterClass Info -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines structures to encapsulate information gleaned from the
// target register and register class definitions.
//
//===----------------------------------------------------------------------===//
#include "CodeGenRegisters.h"
#include "CodeGenTarget.h"
#include "llvm/ADT/IntEqClasses.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/Debug.h"
#include "llvm/TableGen/Error.h"
using namespace llvm;
#define DEBUG_TYPE "regalloc-emitter"
//===----------------------------------------------------------------------===//
// CodeGenSubRegIndex
//===----------------------------------------------------------------------===//
CodeGenSubRegIndex::CodeGenSubRegIndex(Record *R, unsigned Enum)
: TheDef(R), EnumValue(Enum), LaneMask(0), AllSuperRegsCovered(true) {
Name = R->getName();
if (R->getValue("Namespace"))
Namespace = R->getValueAsString("Namespace");
Size = R->getValueAsInt("Size");
Offset = R->getValueAsInt("Offset");
}
CodeGenSubRegIndex::CodeGenSubRegIndex(StringRef N, StringRef Nspace,
unsigned Enum)
: TheDef(nullptr), Name(N), Namespace(Nspace), Size(-1), Offset(-1),
EnumValue(Enum), LaneMask(0), AllSuperRegsCovered(true) {
}
std::string CodeGenSubRegIndex::getQualifiedName() const {
std::string N = getNamespace();
if (!N.empty())
N += "::";
N += getName();
return N;
}
void CodeGenSubRegIndex::updateComponents(CodeGenRegBank &RegBank) {
if (!TheDef)
return;
std::vector<Record*> Comps = TheDef->getValueAsListOfDefs("ComposedOf");
if (!Comps.empty()) {
if (Comps.size() != 2)
PrintFatalError(TheDef->getLoc(),
"ComposedOf must have exactly two entries");
CodeGenSubRegIndex *A = RegBank.getSubRegIdx(Comps[0]);
CodeGenSubRegIndex *B = RegBank.getSubRegIdx(Comps[1]);
CodeGenSubRegIndex *X = A->addComposite(B, this);
if (X)
PrintFatalError(TheDef->getLoc(), "Ambiguous ComposedOf entries");
}
std::vector<Record*> Parts =
TheDef->getValueAsListOfDefs("CoveringSubRegIndices");
if (!Parts.empty()) {
if (Parts.size() < 2)
PrintFatalError(TheDef->getLoc(),
"CoveredBySubRegs must have two or more entries");
SmallVector<CodeGenSubRegIndex*, 8> IdxParts;
for (unsigned i = 0, e = Parts.size(); i != e; ++i)
IdxParts.push_back(RegBank.getSubRegIdx(Parts[i]));
RegBank.addConcatSubRegIndex(IdxParts, this);
}
}
unsigned CodeGenSubRegIndex::computeLaneMask() const {
// Already computed?
if (LaneMask)
return LaneMask;
// Recursion guard, shouldn't be required.
LaneMask = ~0u;
// The lane mask is simply the union of all sub-indices.
unsigned M = 0;
for (const auto &C : Composed)
M |= C.second->computeLaneMask();
assert(M && "Missing lane mask, sub-register cycle?");
LaneMask = M;
return LaneMask;
}
//===----------------------------------------------------------------------===//
// CodeGenRegister
//===----------------------------------------------------------------------===//
CodeGenRegister::CodeGenRegister(Record *R, unsigned Enum)
: TheDef(R),
EnumValue(Enum),
CostPerUse(R->getValueAsInt("CostPerUse")),
CoveredBySubRegs(R->getValueAsBit("CoveredBySubRegs")),
HasDisjunctSubRegs(false),
SubRegsComplete(false),
SuperRegsComplete(false),
TopoSig(~0u)
{}
void CodeGenRegister::buildObjectGraph(CodeGenRegBank &RegBank) {
std::vector<Record*> SRIs = TheDef->getValueAsListOfDefs("SubRegIndices");
std::vector<Record*> SRs = TheDef->getValueAsListOfDefs("SubRegs");
if (SRIs.size() != SRs.size())
PrintFatalError(TheDef->getLoc(),
"SubRegs and SubRegIndices must have the same size");
for (unsigned i = 0, e = SRIs.size(); i != e; ++i) {
ExplicitSubRegIndices.push_back(RegBank.getSubRegIdx(SRIs[i]));
ExplicitSubRegs.push_back(RegBank.getReg(SRs[i]));
}
// Also compute leading super-registers. Each register has a list of
// covered-by-subregs super-registers where it appears as the first explicit
// sub-register.
//
// This is used by computeSecondarySubRegs() to find candidates.
if (CoveredBySubRegs && !ExplicitSubRegs.empty())
ExplicitSubRegs.front()->LeadingSuperRegs.push_back(this);
// Add ad hoc alias links. This is a symmetric relationship between two
// registers, so build a symmetric graph by adding links in both ends.
std::vector<Record*> Aliases = TheDef->getValueAsListOfDefs("Aliases");
for (unsigned i = 0, e = Aliases.size(); i != e; ++i) {
CodeGenRegister *Reg = RegBank.getReg(Aliases[i]);
ExplicitAliases.push_back(Reg);
Reg->ExplicitAliases.push_back(this);
}
}
const std::string &CodeGenRegister::getName() const {
assert(TheDef && "no def");
return TheDef->getName();
}
namespace {
// Iterate over all register units in a set of registers.
class RegUnitIterator {
CodeGenRegister::Vec::const_iterator RegI, RegE;
CodeGenRegister::RegUnitList::iterator UnitI, UnitE;
public:
RegUnitIterator(const CodeGenRegister::Vec &Regs):
RegI(Regs.begin()), RegE(Regs.end()), UnitI(), UnitE() {
if (RegI != RegE) {
UnitI = (*RegI)->getRegUnits().begin();
UnitE = (*RegI)->getRegUnits().end();
advance();
}
}
bool isValid() const { return UnitI != UnitE; }
unsigned operator* () const { assert(isValid()); return *UnitI; }
const CodeGenRegister *getReg() const { assert(isValid()); return *RegI; }
/// Preincrement. Move to the next unit.
void operator++() {
assert(isValid() && "Cannot advance beyond the last operand");
++UnitI;
advance();
}
protected:
void advance() {
while (UnitI == UnitE) {
if (++RegI == RegE)
break;
UnitI = (*RegI)->getRegUnits().begin();
UnitE = (*RegI)->getRegUnits().end();
}
}
};
} // namespace
// Return true of this unit appears in RegUnits.
static bool hasRegUnit(CodeGenRegister::RegUnitList &RegUnits, unsigned Unit) {
return RegUnits.test(Unit);
}
// Inherit register units from subregisters.
// Return true if the RegUnits changed.
bool CodeGenRegister::inheritRegUnits(CodeGenRegBank &RegBank) {
bool changed = false;
for (SubRegMap::const_iterator I = SubRegs.begin(), E = SubRegs.end();
I != E; ++I) {
CodeGenRegister *SR = I->second;
// Merge the subregister's units into this register's RegUnits.
changed |= (RegUnits |= SR->RegUnits);
}
return changed;
}
const CodeGenRegister::SubRegMap &
CodeGenRegister::computeSubRegs(CodeGenRegBank &RegBank) {
// Only compute this map once.
if (SubRegsComplete)
return SubRegs;
SubRegsComplete = true;
HasDisjunctSubRegs = ExplicitSubRegs.size() > 1;
// First insert the explicit subregs and make sure they are fully indexed.
for (unsigned i = 0, e = ExplicitSubRegs.size(); i != e; ++i) {
CodeGenRegister *SR = ExplicitSubRegs[i];
CodeGenSubRegIndex *Idx = ExplicitSubRegIndices[i];
if (!SubRegs.insert(std::make_pair(Idx, SR)).second)
PrintFatalError(TheDef->getLoc(), "SubRegIndex " + Idx->getName() +
" appears twice in Register " + getName());
// Map explicit sub-registers first, so the names take precedence.
// The inherited sub-registers are mapped below.
SubReg2Idx.insert(std::make_pair(SR, Idx));
}
// Keep track of inherited subregs and how they can be reached.
SmallPtrSet<CodeGenRegister*, 8> Orphans;
// Clone inherited subregs and place duplicate entries in Orphans.
// Here the order is important - earlier subregs take precedence.
for (unsigned i = 0, e = ExplicitSubRegs.size(); i != e; ++i) {
CodeGenRegister *SR = ExplicitSubRegs[i];
const SubRegMap &Map = SR->computeSubRegs(RegBank);
HasDisjunctSubRegs |= SR->HasDisjunctSubRegs;
for (SubRegMap::const_iterator SI = Map.begin(), SE = Map.end(); SI != SE;
++SI) {
if (!SubRegs.insert(*SI).second)
Orphans.insert(SI->second);
}
}
// Expand any composed subreg indices.
// If dsub_2 has ComposedOf = [qsub_1, dsub_0], and this register has a
// qsub_1 subreg, add a dsub_2 subreg. Keep growing Indices and process
// expanded subreg indices recursively.
SmallVector<CodeGenSubRegIndex*, 8> Indices = ExplicitSubRegIndices;
for (unsigned i = 0; i != Indices.size(); ++i) {
CodeGenSubRegIndex *Idx = Indices[i];
const CodeGenSubRegIndex::CompMap &Comps = Idx->getComposites();
CodeGenRegister *SR = SubRegs[Idx];
const SubRegMap &Map = SR->computeSubRegs(RegBank);
// Look at the possible compositions of Idx.
// They may not all be supported by SR.
for (CodeGenSubRegIndex::CompMap::const_iterator I = Comps.begin(),
E = Comps.end(); I != E; ++I) {
SubRegMap::const_iterator SRI = Map.find(I->first);
if (SRI == Map.end())
continue; // Idx + I->first doesn't exist in SR.
// Add I->second as a name for the subreg SRI->second, assuming it is
// orphaned, and the name isn't already used for something else.
if (SubRegs.count(I->second) || !Orphans.erase(SRI->second))
continue;
// We found a new name for the orphaned sub-register.
SubRegs.insert(std::make_pair(I->second, SRI->second));
Indices.push_back(I->second);
}
}
// Now Orphans contains the inherited subregisters without a direct index.
// Create inferred indexes for all missing entries.
// Work backwards in the Indices vector in order to compose subregs bottom-up.
// Consider this subreg sequence:
//
// qsub_1 -> dsub_0 -> ssub_0
//
// The qsub_1 -> dsub_0 composition becomes dsub_2, so the ssub_0 register
// can be reached in two different ways:
//
// qsub_1 -> ssub_0
// dsub_2 -> ssub_0
//
// We pick the latter composition because another register may have [dsub_0,
// dsub_1, dsub_2] subregs without necessarily having a qsub_1 subreg. The
// dsub_2 -> ssub_0 composition can be shared.
while (!Indices.empty() && !Orphans.empty()) {
CodeGenSubRegIndex *Idx = Indices.pop_back_val();
CodeGenRegister *SR = SubRegs[Idx];
const SubRegMap &Map = SR->computeSubRegs(RegBank);
for (SubRegMap::const_iterator SI = Map.begin(), SE = Map.end(); SI != SE;
++SI)
if (Orphans.erase(SI->second))
SubRegs[RegBank.getCompositeSubRegIndex(Idx, SI->first)] = SI->second;
}
// Compute the inverse SubReg -> Idx map.
for (SubRegMap::const_iterator SI = SubRegs.begin(), SE = SubRegs.end();
SI != SE; ++SI) {
if (SI->second == this) {
ArrayRef<SMLoc> Loc;
if (TheDef)
Loc = TheDef->getLoc();
PrintFatalError(Loc, "Register " + getName() +
" has itself as a sub-register");
}
// Compute AllSuperRegsCovered.
if (!CoveredBySubRegs)
SI->first->AllSuperRegsCovered = false;
// Ensure that every sub-register has a unique name.
DenseMap<const CodeGenRegister*, CodeGenSubRegIndex*>::iterator Ins =
SubReg2Idx.insert(std::make_pair(SI->second, SI->first)).first;
if (Ins->second == SI->first)
continue;
// Trouble: Two different names for SI->second.
ArrayRef<SMLoc> Loc;
if (TheDef)
Loc = TheDef->getLoc();
PrintFatalError(Loc, "Sub-register can't have two names: " +
SI->second->getName() + " available as " +
SI->first->getName() + " and " + Ins->second->getName());
}
// Derive possible names for sub-register concatenations from any explicit
// sub-registers. By doing this before computeSecondarySubRegs(), we ensure
// that getConcatSubRegIndex() won't invent any concatenated indices that the
// user already specified.
for (unsigned i = 0, e = ExplicitSubRegs.size(); i != e; ++i) {
CodeGenRegister *SR = ExplicitSubRegs[i];
if (!SR->CoveredBySubRegs || SR->ExplicitSubRegs.size() <= 1)
continue;
// SR is composed of multiple sub-regs. Find their names in this register.
SmallVector<CodeGenSubRegIndex*, 8> Parts;
for (unsigned j = 0, e = SR->ExplicitSubRegs.size(); j != e; ++j)
Parts.push_back(getSubRegIndex(SR->ExplicitSubRegs[j]));
// Offer this as an existing spelling for the concatenation of Parts.
RegBank.addConcatSubRegIndex(Parts, ExplicitSubRegIndices[i]);
}
// Initialize RegUnitList. Because getSubRegs is called recursively, this
// processes the register hierarchy in postorder.
//
// Inherit all sub-register units. It is good enough to look at the explicit
// sub-registers, the other registers won't contribute any more units.
for (unsigned i = 0, e = ExplicitSubRegs.size(); i != e; ++i) {
CodeGenRegister *SR = ExplicitSubRegs[i];
RegUnits |= SR->RegUnits;
}
// Absent any ad hoc aliasing, we create one register unit per leaf register.
// These units correspond to the maximal cliques in the register overlap
// graph which is optimal.
//
// When there is ad hoc aliasing, we simply create one unit per edge in the
// undirected ad hoc aliasing graph. Technically, we could do better by
// identifying maximal cliques in the ad hoc graph, but cliques larger than 2
// are extremely rare anyway (I've never seen one), so we don't bother with
// the added complexity.
for (unsigned i = 0, e = ExplicitAliases.size(); i != e; ++i) {
CodeGenRegister *AR = ExplicitAliases[i];
// Only visit each edge once.
if (AR->SubRegsComplete)
continue;
// Create a RegUnit representing this alias edge, and add it to both
// registers.
unsigned Unit = RegBank.newRegUnit(this, AR);
RegUnits.set(Unit);
AR->RegUnits.set(Unit);
}
// Finally, create units for leaf registers without ad hoc aliases. Note that
// a leaf register with ad hoc aliases doesn't get its own unit - it isn't
// necessary. This means the aliasing leaf registers can share a single unit.
if (RegUnits.empty())
RegUnits.set(RegBank.newRegUnit(this));
// We have now computed the native register units. More may be adopted later
// for balancing purposes.
NativeRegUnits = RegUnits;
return SubRegs;
}
// In a register that is covered by its sub-registers, try to find redundant
// sub-registers. For example:
//
// QQ0 = {Q0, Q1}
// Q0 = {D0, D1}
// Q1 = {D2, D3}
//
// We can infer that D1_D2 is also a sub-register, even if it wasn't named in
// the register definition.
//
// The explicitly specified registers form a tree. This function discovers
// sub-register relationships that would force a DAG.
//
void CodeGenRegister::computeSecondarySubRegs(CodeGenRegBank &RegBank) {
// Collect new sub-registers first, add them later.
SmallVector<SubRegMap::value_type, 8> NewSubRegs;
// Look at the leading super-registers of each sub-register. Those are the
// candidates for new sub-registers, assuming they are fully contained in
// this register.
for (SubRegMap::iterator I = SubRegs.begin(), E = SubRegs.end(); I != E; ++I){
const CodeGenRegister *SubReg = I->second;
const CodeGenRegister::SuperRegList &Leads = SubReg->LeadingSuperRegs;
for (unsigned i = 0, e = Leads.size(); i != e; ++i) {
CodeGenRegister *Cand = const_cast<CodeGenRegister*>(Leads[i]);
// Already got this sub-register?
if (Cand == this || getSubRegIndex(Cand))
continue;
// Check if each component of Cand is already a sub-register.
// We know that the first component is I->second, and is present with the
// name I->first.
SmallVector<CodeGenSubRegIndex*, 8> Parts(1, I->first);
assert(!Cand->ExplicitSubRegs.empty() &&
"Super-register has no sub-registers");
for (unsigned j = 1, e = Cand->ExplicitSubRegs.size(); j != e; ++j) {
if (CodeGenSubRegIndex *Idx = getSubRegIndex(Cand->ExplicitSubRegs[j]))
Parts.push_back(Idx);
else {
// Sub-register doesn't exist.
Parts.clear();
break;
}
}
// If some Cand sub-register is not part of this register, or if Cand only
// has one sub-register, there is nothing to do.
if (Parts.size() <= 1)
continue;
// Each part of Cand is a sub-register of this. Make the full Cand also
// a sub-register with a concatenated sub-register index.
CodeGenSubRegIndex *Concat= RegBank.getConcatSubRegIndex(Parts);
NewSubRegs.push_back(std::make_pair(Concat, Cand));
}
}
// Now add all the new sub-registers.
for (unsigned i = 0, e = NewSubRegs.size(); i != e; ++i) {
// Don't add Cand if another sub-register is already using the index.
if (!SubRegs.insert(NewSubRegs[i]).second)
continue;
CodeGenSubRegIndex *NewIdx = NewSubRegs[i].first;
CodeGenRegister *NewSubReg = NewSubRegs[i].second;
SubReg2Idx.insert(std::make_pair(NewSubReg, NewIdx));
}
// Create sub-register index composition maps for the synthesized indices.
for (unsigned i = 0, e = NewSubRegs.size(); i != e; ++i) {
CodeGenSubRegIndex *NewIdx = NewSubRegs[i].first;
CodeGenRegister *NewSubReg = NewSubRegs[i].second;
for (SubRegMap::const_iterator SI = NewSubReg->SubRegs.begin(),
SE = NewSubReg->SubRegs.end(); SI != SE; ++SI) {
CodeGenSubRegIndex *SubIdx = getSubRegIndex(SI->second);
if (!SubIdx)
PrintFatalError(TheDef->getLoc(), "No SubRegIndex for " +
SI->second->getName() + " in " + getName());
NewIdx->addComposite(SI->first, SubIdx);
}
}
}
void CodeGenRegister::computeSuperRegs(CodeGenRegBank &RegBank) {
// Only visit each register once.
if (SuperRegsComplete)
return;
SuperRegsComplete = true;
// Make sure all sub-registers have been visited first, so the super-reg
// lists will be topologically ordered.
for (SubRegMap::const_iterator I = SubRegs.begin(), E = SubRegs.end();
I != E; ++I)
I->second->computeSuperRegs(RegBank);
// Now add this as a super-register on all sub-registers.
// Also compute the TopoSigId in post-order.
TopoSigId Id;
for (SubRegMap::const_iterator I = SubRegs.begin(), E = SubRegs.end();
I != E; ++I) {
// Topological signature computed from SubIdx, TopoId(SubReg).
// Loops and idempotent indices have TopoSig = ~0u.
Id.push_back(I->first->EnumValue);
Id.push_back(I->second->TopoSig);
// Don't add duplicate entries.
if (!I->second->SuperRegs.empty() && I->second->SuperRegs.back() == this)
continue;
I->second->SuperRegs.push_back(this);
}
TopoSig = RegBank.getTopoSig(Id);
}
void
CodeGenRegister::addSubRegsPreOrder(SetVector<const CodeGenRegister*> &OSet,
CodeGenRegBank &RegBank) const {
assert(SubRegsComplete && "Must precompute sub-registers");
for (unsigned i = 0, e = ExplicitSubRegs.size(); i != e; ++i) {
CodeGenRegister *SR = ExplicitSubRegs[i];
if (OSet.insert(SR))
SR->addSubRegsPreOrder(OSet, RegBank);
}
// Add any secondary sub-registers that weren't part of the explicit tree.
for (SubRegMap::const_iterator I = SubRegs.begin(), E = SubRegs.end();
I != E; ++I)
OSet.insert(I->second);
}
// Get the sum of this register's unit weights.
unsigned CodeGenRegister::getWeight(const CodeGenRegBank &RegBank) const {
unsigned Weight = 0;
for (RegUnitList::iterator I = RegUnits.begin(), E = RegUnits.end();
I != E; ++I) {
Weight += RegBank.getRegUnit(*I).Weight;
}
return Weight;
}
//===----------------------------------------------------------------------===//
// RegisterTuples
//===----------------------------------------------------------------------===//
// A RegisterTuples def is used to generate pseudo-registers from lists of
// sub-registers. We provide a SetTheory expander class that returns the new
// registers.
namespace {
struct TupleExpander : SetTheory::Expander {
void expand(SetTheory &ST, Record *Def, SetTheory::RecSet &Elts) override {
std::vector<Record*> Indices = Def->getValueAsListOfDefs("SubRegIndices");
unsigned Dim = Indices.size();
ListInit *SubRegs = Def->getValueAsListInit("SubRegs");
if (Dim != SubRegs->getSize())
PrintFatalError(Def->getLoc(), "SubRegIndices and SubRegs size mismatch");
if (Dim < 2)
PrintFatalError(Def->getLoc(),
"Tuples must have at least 2 sub-registers");
// Evaluate the sub-register lists to be zipped.
unsigned Length = ~0u;
SmallVector<SetTheory::RecSet, 4> Lists(Dim);
for (unsigned i = 0; i != Dim; ++i) {
ST.evaluate(SubRegs->getElement(i), Lists[i], Def->getLoc());
Length = std::min(Length, unsigned(Lists[i].size()));
}
if (Length == 0)
return;
// Precompute some types.
Record *RegisterCl = Def->getRecords().getClass("Register");
RecTy *RegisterRecTy = RecordRecTy::get(RegisterCl);
StringInit *BlankName = StringInit::get("");
// Zip them up.
for (unsigned n = 0; n != Length; ++n) {
std::string Name;
Record *Proto = Lists[0][n];
std::vector<Init*> Tuple;
unsigned CostPerUse = 0;
for (unsigned i = 0; i != Dim; ++i) {
Record *Reg = Lists[i][n];
if (i) Name += '_';
Name += Reg->getName();
Tuple.push_back(DefInit::get(Reg));
CostPerUse = std::max(CostPerUse,
unsigned(Reg->getValueAsInt("CostPerUse")));
}
// Create a new Record representing the synthesized register. This record
// is only for consumption by CodeGenRegister, it is not added to the
// RecordKeeper.
Record *NewReg = new Record(Name, Def->getLoc(), Def->getRecords());
Elts.insert(NewReg);
// Copy Proto super-classes.
ArrayRef<Record *> Supers = Proto->getSuperClasses();
ArrayRef<SMRange> Ranges = Proto->getSuperClassRanges();
for (unsigned i = 0, e = Supers.size(); i != e; ++i)
NewReg->addSuperClass(Supers[i], Ranges[i]);
// Copy Proto fields.
for (unsigned i = 0, e = Proto->getValues().size(); i != e; ++i) {
RecordVal RV = Proto->getValues()[i];
// Skip existing fields, like NAME.
if (NewReg->getValue(RV.getNameInit()))
continue;
StringRef Field = RV.getName();
// Replace the sub-register list with Tuple.
if (Field == "SubRegs")
RV.setValue(ListInit::get(Tuple, RegisterRecTy));
// Provide a blank AsmName. MC hacks are required anyway.
if (Field == "AsmName")
RV.setValue(BlankName);
// CostPerUse is aggregated from all Tuple members.
if (Field == "CostPerUse")
RV.setValue(IntInit::get(CostPerUse));
// Composite registers are always covered by sub-registers.
if (Field == "CoveredBySubRegs")
RV.setValue(BitInit::get(true));
// Copy fields from the RegisterTuples def.
if (Field == "SubRegIndices" ||
Field == "CompositeIndices") {
NewReg->addValue(*Def->getValue(Field));
continue;
}
// Some fields get their default uninitialized value.
if (Field == "DwarfNumbers" ||
Field == "DwarfAlias" ||
Field == "Aliases") {
if (const RecordVal *DefRV = RegisterCl->getValue(Field))
NewReg->addValue(*DefRV);
continue;
}
// Everything else is copied from Proto.
NewReg->addValue(RV);
}
}
}
};
}
//===----------------------------------------------------------------------===//
// CodeGenRegisterClass
//===----------------------------------------------------------------------===//
static void sortAndUniqueRegisters(CodeGenRegister::Vec &M) {
std::sort(M.begin(), M.end(), deref<llvm::less>());
M.erase(std::unique(M.begin(), M.end(), deref<llvm::equal>()), M.end());
}
CodeGenRegisterClass::CodeGenRegisterClass(CodeGenRegBank &RegBank, Record *R)
: TheDef(R),
Name(R->getName()),
TopoSigs(RegBank.getNumTopoSigs()),
EnumValue(-1),
LaneMask(0) {
// Rename anonymous register classes.
if (R->getName().size() > 9 && R->getName()[9] == '.') {
static unsigned AnonCounter = 0;
R->setName("AnonRegClass_" + utostr(AnonCounter++));
}
std::vector<Record*> TypeList = R->getValueAsListOfDefs("RegTypes");
for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
Record *Type = TypeList[i];
if (!Type->isSubClassOf("ValueType"))
PrintFatalError("RegTypes list member '" + Type->getName() +
"' does not derive from the ValueType class!");
VTs.push_back(getValueType(Type));
}
assert(!VTs.empty() && "RegisterClass must contain at least one ValueType!");
// Allocation order 0 is the full set. AltOrders provides others.
const SetTheory::RecVec *Elements = RegBank.getSets().expand(R);
ListInit *AltOrders = R->getValueAsListInit("AltOrders");
Orders.resize(1 + AltOrders->size());
// Default allocation order always contains all registers.
for (unsigned i = 0, e = Elements->size(); i != e; ++i) {
Orders[0].push_back((*Elements)[i]);
const CodeGenRegister *Reg = RegBank.getReg((*Elements)[i]);
Members.push_back(Reg);
TopoSigs.set(Reg->getTopoSig());
}
sortAndUniqueRegisters(Members);
// Alternative allocation orders may be subsets.
SetTheory::RecSet Order;
for (unsigned i = 0, e = AltOrders->size(); i != e; ++i) {
RegBank.getSets().evaluate(AltOrders->getElement(i), Order, R->getLoc());
Orders[1 + i].append(Order.begin(), Order.end());
// Verify that all altorder members are regclass members.
while (!Order.empty()) {
CodeGenRegister *Reg = RegBank.getReg(Order.back());
Order.pop_back();
if (!contains(Reg))
PrintFatalError(R->getLoc(), " AltOrder register " + Reg->getName() +
" is not a class member");
}
}
// Allow targets to override the size in bits of the RegisterClass.
unsigned Size = R->getValueAsInt("Size");
Namespace = R->getValueAsString("Namespace");
SpillSize = Size ? Size : MVT(VTs[0]).getSizeInBits();
SpillAlignment = R->getValueAsInt("Alignment");
CopyCost = R->getValueAsInt("CopyCost");
Allocatable = R->getValueAsBit("isAllocatable");
AltOrderSelect = R->getValueAsString("AltOrderSelect");
int AllocationPriority = R->getValueAsInt("AllocationPriority");
if (AllocationPriority < 0 || AllocationPriority > 63)
PrintFatalError(R->getLoc(), "AllocationPriority out of range [0,63]");
this->AllocationPriority = AllocationPriority;
}
// Create an inferred register class that was missing from the .td files.
// Most properties will be inherited from the closest super-class after the
// class structure has been computed.
CodeGenRegisterClass::CodeGenRegisterClass(CodeGenRegBank &RegBank,
StringRef Name, Key Props)
: Members(*Props.Members),
TheDef(nullptr),
Name(Name),
TopoSigs(RegBank.getNumTopoSigs()),
EnumValue(-1),
SpillSize(Props.SpillSize),
SpillAlignment(Props.SpillAlignment),
CopyCost(0),
Allocatable(true),
AllocationPriority(0) {
for (const auto R : Members)
TopoSigs.set(R->getTopoSig());
}
// Compute inherited propertied for a synthesized register class.
void CodeGenRegisterClass::inheritProperties(CodeGenRegBank &RegBank) {
assert(!getDef() && "Only synthesized classes can inherit properties");
assert(!SuperClasses.empty() && "Synthesized class without super class");
// The last super-class is the smallest one.
CodeGenRegisterClass &Super = *SuperClasses.back();
// Most properties are copied directly.
// Exceptions are members, size, and alignment
Namespace = Super.Namespace;
VTs = Super.VTs;
CopyCost = Super.CopyCost;
Allocatable = Super.Allocatable;
AltOrderSelect = Super.AltOrderSelect;
AllocationPriority = Super.AllocationPriority;
// Copy all allocation orders, filter out foreign registers from the larger
// super-class.
Orders.resize(Super.Orders.size());
for (unsigned i = 0, ie = Super.Orders.size(); i != ie; ++i)
for (unsigned j = 0, je = Super.Orders[i].size(); j != je; ++j)
if (contains(RegBank.getReg(Super.Orders[i][j])))
Orders[i].push_back(Super.Orders[i][j]);
}
bool CodeGenRegisterClass::contains(const CodeGenRegister *Reg) const {
return std::binary_search(Members.begin(), Members.end(), Reg,
deref<llvm::less>());
}
namespace llvm {
raw_ostream &operator<<(raw_ostream &OS, const CodeGenRegisterClass::Key &K) {
OS << "{ S=" << K.SpillSize << ", A=" << K.SpillAlignment;
for (const auto R : *K.Members)
OS << ", " << R->getName();
return OS << " }";
}
}
// This is a simple lexicographical order that can be used to search for sets.
// It is not the same as the topological order provided by TopoOrderRC.
bool CodeGenRegisterClass::Key::
operator<(const CodeGenRegisterClass::Key &B) const {
assert(Members && B.Members);
return std::tie(*Members, SpillSize, SpillAlignment) <
std::tie(*B.Members, B.SpillSize, B.SpillAlignment);
}
// Returns true if RC is a strict subclass.
// RC is a sub-class of this class if it is a valid replacement for any
// instruction operand where a register of this classis required. It must
// satisfy these conditions:
//
// 1. All RC registers are also in this.
// 2. The RC spill size must not be smaller than our spill size.
// 3. RC spill alignment must be compatible with ours.
//
static bool testSubClass(const CodeGenRegisterClass *A,
const CodeGenRegisterClass *B) {
return A->SpillAlignment && B->SpillAlignment % A->SpillAlignment == 0 &&
A->SpillSize <= B->SpillSize &&
std::includes(A->getMembers().begin(), A->getMembers().end(),
B->getMembers().begin(), B->getMembers().end(),
deref<llvm::less>());
}
/// Sorting predicate for register classes. This provides a topological
/// ordering that arranges all register classes before their sub-classes.
///
/// Register classes with the same registers, spill size, and alignment form a
/// clique. They will be ordered alphabetically.
///
static bool TopoOrderRC(const CodeGenRegisterClass &PA,
const CodeGenRegisterClass &PB) {
auto *A = &PA;
auto *B = &PB;
if (A == B)
return 0;
// Order by ascending spill size.
if (A->SpillSize < B->SpillSize)
return true;
if (A->SpillSize > B->SpillSize)
return false;
// Order by ascending spill alignment.
if (A->SpillAlignment < B->SpillAlignment)
return true;
if (A->SpillAlignment > B->SpillAlignment)
return false;
// Order by descending set size. Note that the classes' allocation order may
// not have been computed yet. The Members set is always vaild.
if (A->getMembers().size() > B->getMembers().size())
return true;
if (A->getMembers().size() < B->getMembers().size())
return false;
// Finally order by name as a tie breaker.
return StringRef(A->getName()) < B->getName();
}
std::string CodeGenRegisterClass::getQualifiedName() const {
if (Namespace.empty())
return getName();
else
return Namespace + "::" + getName();
}
// Compute sub-classes of all register classes.
// Assume the classes are ordered topologically.
void CodeGenRegisterClass::computeSubClasses(CodeGenRegBank &RegBank) {
auto &RegClasses = RegBank.getRegClasses();
// Visit backwards so sub-classes are seen first.
for (auto I = RegClasses.rbegin(), E = RegClasses.rend(); I != E; ++I) {
CodeGenRegisterClass &RC = *I;
RC.SubClasses.resize(RegClasses.size());
RC.SubClasses.set(RC.EnumValue);
// Normally, all subclasses have IDs >= rci, unless RC is part of a clique.
for (auto I2 = I.base(), E2 = RegClasses.end(); I2 != E2; ++I2) {
CodeGenRegisterClass &SubRC = *I2;
if (RC.SubClasses.test(SubRC.EnumValue))
continue;
if (!testSubClass(&RC, &SubRC))
continue;
// SubRC is a sub-class. Grap all its sub-classes so we won't have to
// check them again.
RC.SubClasses |= SubRC.SubClasses;
}
// Sweep up missed clique members. They will be immediately preceding RC.
for (auto I2 = std::next(I); I2 != E && testSubClass(&RC, &*I2); ++I2)
RC.SubClasses.set(I2->EnumValue);
}
// Compute the SuperClasses lists from the SubClasses vectors.
for (auto &RC : RegClasses) {
const BitVector &SC = RC.getSubClasses();
auto I = RegClasses.begin();
for (int s = 0, next_s = SC.find_first(); next_s != -1;
next_s = SC.find_next(s)) {
std::advance(I, next_s - s);
s = next_s;
if (&*I == &RC)
continue;
I->SuperClasses.push_back(&RC);
}
}
// With the class hierarchy in place, let synthesized register classes inherit
// properties from their closest super-class. The iteration order here can
// propagate properties down multiple levels.
for (auto &RC : RegClasses)
if (!RC.getDef())
RC.inheritProperties(RegBank);
}
void CodeGenRegisterClass::getSuperRegClasses(const CodeGenSubRegIndex *SubIdx,
BitVector &Out) const {
auto FindI = SuperRegClasses.find(SubIdx);
if (FindI == SuperRegClasses.end())
return;
for (CodeGenRegisterClass *RC : FindI->second)
Out.set(RC->EnumValue);
}
// Populate a unique sorted list of units from a register set.
void CodeGenRegisterClass::buildRegUnitSet(
std::vector<unsigned> &RegUnits) const {
std::vector<unsigned> TmpUnits;
for (RegUnitIterator UnitI(Members); UnitI.isValid(); ++UnitI)
TmpUnits.push_back(*UnitI);
std::sort(TmpUnits.begin(), TmpUnits.end());
std::unique_copy(TmpUnits.begin(), TmpUnits.end(),
std::back_inserter(RegUnits));
}
//===----------------------------------------------------------------------===//
// CodeGenRegBank
//===----------------------------------------------------------------------===//
CodeGenRegBank::CodeGenRegBank(RecordKeeper &Records) {
// Configure register Sets to understand register classes and tuples.
Sets.addFieldExpander("RegisterClass", "MemberList");
Sets.addFieldExpander("CalleeSavedRegs", "SaveList");
Sets.addExpander("RegisterTuples", new TupleExpander());
// Read in the user-defined (named) sub-register indices.
// More indices will be synthesized later.
std::vector<Record*> SRIs = Records.getAllDerivedDefinitions("SubRegIndex");
std::sort(SRIs.begin(), SRIs.end(), LessRecord());
for (unsigned i = 0, e = SRIs.size(); i != e; ++i)
getSubRegIdx(SRIs[i]);
// Build composite maps from ComposedOf fields.
for (auto &Idx : SubRegIndices)
Idx.updateComponents(*this);
// Read in the register definitions.
std::vector<Record*> Regs = Records.getAllDerivedDefinitions("Register");
std::sort(Regs.begin(), Regs.end(), LessRecordRegister());
// Assign the enumeration values.
for (unsigned i = 0, e = Regs.size(); i != e; ++i)
getReg(Regs[i]);
// Expand tuples and number the new registers.
std::vector<Record*> Tups =
Records.getAllDerivedDefinitions("RegisterTuples");
for (Record *R : Tups) {
std::vector<Record *> TupRegs = *Sets.expand(R);
std::sort(TupRegs.begin(), TupRegs.end(), LessRecordRegister());
for (Record *RC : TupRegs)
getReg(RC);
}
// Now all the registers are known. Build the object graph of explicit
// register-register references.
for (auto &Reg : Registers)
Reg.buildObjectGraph(*this);
// Compute register name map.
for (auto &Reg : Registers)
// FIXME: This could just be RegistersByName[name] = register, except that
// causes some failures in MIPS - perhaps they have duplicate register name
// entries? (or maybe there's a reason for it - I don't know much about this
// code, just drive-by refactoring)
RegistersByName.insert(
std::make_pair(Reg.TheDef->getValueAsString("AsmName"), &Reg));
// Precompute all sub-register maps.
// This will create Composite entries for all inferred sub-register indices.
for (auto &Reg : Registers)
Reg.computeSubRegs(*this);
// Infer even more sub-registers by combining leading super-registers.
for (auto &Reg : Registers)
if (Reg.CoveredBySubRegs)
Reg.computeSecondarySubRegs(*this);
// After the sub-register graph is complete, compute the topologically
// ordered SuperRegs list.
for (auto &Reg : Registers)
Reg.computeSuperRegs(*this);
// Native register units are associated with a leaf register. They've all been
// discovered now.
NumNativeRegUnits = RegUnits.size();
// Read in register class definitions.
std::vector<Record*> RCs = Records.getAllDerivedDefinitions("RegisterClass");
if (RCs.empty())
PrintFatalError("No 'RegisterClass' subclasses defined!");
// Allocate user-defined register classes.
for (auto *RC : RCs) {
RegClasses.push_back(CodeGenRegisterClass(*this, RC));
addToMaps(&RegClasses.back());
}
// Infer missing classes to create a full algebra.
computeInferredRegisterClasses();
// Order register classes topologically and assign enum values.
RegClasses.sort(TopoOrderRC);
unsigned i = 0;
for (auto &RC : RegClasses)
RC.EnumValue = i++;
CodeGenRegisterClass::computeSubClasses(*this);
}
// Create a synthetic CodeGenSubRegIndex without a corresponding Record.
CodeGenSubRegIndex*
CodeGenRegBank::createSubRegIndex(StringRef Name, StringRef Namespace) {
SubRegIndices.emplace_back(Name, Namespace, SubRegIndices.size() + 1);
return &SubRegIndices.back();
}
CodeGenSubRegIndex *CodeGenRegBank::getSubRegIdx(Record *Def) {
CodeGenSubRegIndex *&Idx = Def2SubRegIdx[Def];
if (Idx)
return Idx;
SubRegIndices.emplace_back(Def, SubRegIndices.size() + 1);
Idx = &SubRegIndices.back();
return Idx;
}
CodeGenRegister *CodeGenRegBank::getReg(Record *Def) {
CodeGenRegister *&Reg = Def2Reg[Def];
if (Reg)
return Reg;
Registers.emplace_back(Def, Registers.size() + 1);
Reg = &Registers.back();
return Reg;
}
void CodeGenRegBank::addToMaps(CodeGenRegisterClass *RC) {
if (Record *Def = RC->getDef())
Def2RC.insert(std::make_pair(Def, RC));
// Duplicate classes are rejected by insert().
// That's OK, we only care about the properties handled by CGRC::Key.
CodeGenRegisterClass::Key K(*RC);
Key2RC.insert(std::make_pair(K, RC));
}
// Create a synthetic sub-class if it is missing.
CodeGenRegisterClass*
CodeGenRegBank::getOrCreateSubClass(const CodeGenRegisterClass *RC,
const CodeGenRegister::Vec *Members,
StringRef Name) {
// Synthetic sub-class has the same size and alignment as RC.
CodeGenRegisterClass::Key K(Members, RC->SpillSize, RC->SpillAlignment);
RCKeyMap::const_iterator FoundI = Key2RC.find(K);
if (FoundI != Key2RC.end())
return FoundI->second;
// Sub-class doesn't exist, create a new one.
RegClasses.push_back(CodeGenRegisterClass(*this, Name, K));
addToMaps(&RegClasses.back());
return &RegClasses.back();
}
CodeGenRegisterClass *CodeGenRegBank::getRegClass(Record *Def) {
if (CodeGenRegisterClass *RC = Def2RC[Def])
return RC;
PrintFatalError(Def->getLoc(), "Not a known RegisterClass!");
}
CodeGenSubRegIndex*
CodeGenRegBank::getCompositeSubRegIndex(CodeGenSubRegIndex *A,
CodeGenSubRegIndex *B) {
// Look for an existing entry.
CodeGenSubRegIndex *Comp = A->compose(B);
if (Comp)
return Comp;
// None exists, synthesize one.
std::string Name = A->getName() + "_then_" + B->getName();
Comp = createSubRegIndex(Name, A->getNamespace());
A->addComposite(B, Comp);
return Comp;
}
CodeGenSubRegIndex *CodeGenRegBank::
getConcatSubRegIndex(const SmallVector<CodeGenSubRegIndex *, 8> &Parts) {
assert(Parts.size() > 1 && "Need two parts to concatenate");
// Look for an existing entry.
CodeGenSubRegIndex *&Idx = ConcatIdx[Parts];
if (Idx)
return Idx;
// None exists, synthesize one.
std::string Name = Parts.front()->getName();
// Determine whether all parts are contiguous.
bool isContinuous = true;
unsigned Size = Parts.front()->Size;
unsigned LastOffset = Parts.front()->Offset;
unsigned LastSize = Parts.front()->Size;
for (unsigned i = 1, e = Parts.size(); i != e; ++i) {
Name += '_';
Name += Parts[i]->getName();
Size += Parts[i]->Size;
if (Parts[i]->Offset != (LastOffset + LastSize))
isContinuous = false;
LastOffset = Parts[i]->Offset;
LastSize = Parts[i]->Size;
}
Idx = createSubRegIndex(Name, Parts.front()->getNamespace());
Idx->Size = Size;
Idx->Offset = isContinuous ? Parts.front()->Offset : -1;
return Idx;
}
void CodeGenRegBank::computeComposites() {
// Keep track of TopoSigs visited. We only need to visit each TopoSig once,
// and many registers will share TopoSigs on regular architectures.
BitVector TopoSigs(getNumTopoSigs());
for (const auto &Reg1 : Registers) {
// Skip identical subreg structures already processed.
if (TopoSigs.test(Reg1.getTopoSig()))
continue;
TopoSigs.set(Reg1.getTopoSig());
const CodeGenRegister::SubRegMap &SRM1 = Reg1.getSubRegs();
for (CodeGenRegister::SubRegMap::const_iterator i1 = SRM1.begin(),
e1 = SRM1.end(); i1 != e1; ++i1) {
CodeGenSubRegIndex *Idx1 = i1->first;
CodeGenRegister *Reg2 = i1->second;
// Ignore identity compositions.
if (&Reg1 == Reg2)
continue;
const CodeGenRegister::SubRegMap &SRM2 = Reg2->getSubRegs();
// Try composing Idx1 with another SubRegIndex.
for (CodeGenRegister::SubRegMap::const_iterator i2 = SRM2.begin(),
e2 = SRM2.end(); i2 != e2; ++i2) {
CodeGenSubRegIndex *Idx2 = i2->first;
CodeGenRegister *Reg3 = i2->second;
// Ignore identity compositions.
if (Reg2 == Reg3)
continue;
// OK Reg1:IdxPair == Reg3. Find the index with Reg:Idx == Reg3.
CodeGenSubRegIndex *Idx3 = Reg1.getSubRegIndex(Reg3);
assert(Idx3 && "Sub-register doesn't have an index");
// Conflicting composition? Emit a warning but allow it.
if (CodeGenSubRegIndex *Prev = Idx1->addComposite(Idx2, Idx3))
PrintWarning(Twine("SubRegIndex ") + Idx1->getQualifiedName() +
" and " + Idx2->getQualifiedName() +
" compose ambiguously as " + Prev->getQualifiedName() +
" or " + Idx3->getQualifiedName());
}
}
}
}
// Compute lane masks. This is similar to register units, but at the
// sub-register index level. Each bit in the lane mask is like a register unit
// class, and two lane masks will have a bit in common if two sub-register
// indices overlap in some register.
//
// Conservatively share a lane mask bit if two sub-register indices overlap in
// some registers, but not in others. That shouldn't happen a lot.
void CodeGenRegBank::computeSubRegLaneMasks() {
// First assign individual bits to all the leaf indices.
unsigned Bit = 0;
// Determine mask of lanes that cover their registers.
CoveringLanes = ~0u;
for (auto &Idx : SubRegIndices) {
if (Idx.getComposites().empty()) {
Idx.LaneMask = 1u << Bit;
// Share bit 31 in the unlikely case there are more than 32 leafs.
//
// Sharing bits is harmless; it allows graceful degradation in targets
// with more than 32 vector lanes. They simply get a limited resolution
// view of lanes beyond the 32nd.
//
// See also the comment for getSubRegIndexLaneMask().
if (Bit < 31)
++Bit;
else
// Once bit 31 is shared among multiple leafs, the 'lane' it represents
// is no longer covering its registers.
CoveringLanes &= ~(1u << Bit);
} else {
Idx.LaneMask = 0;
}
}
// Compute transformation sequences for composeSubRegIndexLaneMask. The idea
// here is that for each possible target subregister we look at the leafs
// in the subregister graph that compose for this target and create
// transformation sequences for the lanemasks. Each step in the sequence
// consists of a bitmask and a bitrotate operation. As the rotation amounts
// are usually the same for many subregisters we can easily combine the steps
// by combining the masks.
for (const auto &Idx : SubRegIndices) {
const auto &Composites = Idx.getComposites();
auto &LaneTransforms = Idx.CompositionLaneMaskTransform;
// Go through all leaf subregisters and find the ones that compose with Idx.
// These make out all possible valid bits in the lane mask we want to
// transform. Looking only at the leafs ensure that only a single bit in
// the mask is set.
unsigned NextBit = 0;
for (auto &Idx2 : SubRegIndices) {
// Skip non-leaf subregisters.
if (!Idx2.getComposites().empty())
continue;
// Replicate the behaviour from the lane mask generation loop above.
unsigned SrcBit = NextBit;
unsigned SrcMask = 1u << SrcBit;
if (NextBit < 31)
++NextBit;
assert(Idx2.LaneMask == SrcMask);
// Get the composed subregister if there is any.
auto C = Composites.find(&Idx2);
if (C == Composites.end())
continue;
const CodeGenSubRegIndex *Composite = C->second;
// The Composed subreg should be a leaf subreg too
assert(Composite->getComposites().empty());
// Create Mask+Rotate operation and merge with existing ops if possible.
unsigned DstBit = Log2_32(Composite->LaneMask);
int Shift = DstBit - SrcBit;
uint8_t RotateLeft = Shift >= 0 ? (uint8_t)Shift : 32+Shift;
for (auto &I : LaneTransforms) {
if (I.RotateLeft == RotateLeft) {
I.Mask |= SrcMask;
SrcMask = 0;
}
}
if (SrcMask != 0) {
MaskRolPair MaskRol = { SrcMask, RotateLeft };
LaneTransforms.push_back(MaskRol);
}
}
// Optimize if the transformation consists of one step only: Set mask to
// 0xffffffff (including some irrelevant invalid bits) so that it should
// merge with more entries later while compressing the table.
if (LaneTransforms.size() == 1)
LaneTransforms[0].Mask = ~0u;
// Further compression optimization: For invalid compositions resulting
// in a sequence with 0 entries we can just pick any other. Choose
// Mask 0xffffffff with Rotation 0.
if (LaneTransforms.size() == 0) {
MaskRolPair P = { ~0u, 0 };
LaneTransforms.push_back(P);
}
}
// FIXME: What if ad-hoc aliasing introduces overlaps that aren't represented
// by the sub-register graph? This doesn't occur in any known targets.
// Inherit lanes from composites.
for (const auto &Idx : SubRegIndices) {
unsigned Mask = Idx.computeLaneMask();
// If some super-registers without CoveredBySubRegs use this index, we can
// no longer assume that the lanes are covering their registers.
if (!Idx.AllSuperRegsCovered)
CoveringLanes &= ~Mask;
}
// Compute lane mask combinations for register classes.
for (auto &RegClass : RegClasses) {
unsigned LaneMask = 0;
for (const auto &SubRegIndex : SubRegIndices) {
if (RegClass.getSubClassWithSubReg(&SubRegIndex) == nullptr)
continue;
LaneMask |= SubRegIndex.LaneMask;
}
RegClass.LaneMask = LaneMask;
}
}
namespace {
// UberRegSet is a helper class for computeRegUnitWeights. Each UberRegSet is
// the transitive closure of the union of overlapping register
// classes. Together, the UberRegSets form a partition of the registers. If we
// consider overlapping register classes to be connected, then each UberRegSet
// is a set of connected components.
//
// An UberRegSet will likely be a horizontal slice of register names of
// the same width. Nontrivial subregisters should then be in a separate
// UberRegSet. But this property isn't required for valid computation of
// register unit weights.
//
// A Weight field caches the max per-register unit weight in each UberRegSet.
//
// A set of SingularDeterminants flags single units of some register in this set
// for which the unit weight equals the set weight. These units should not have
// their weight increased.
struct UberRegSet {
CodeGenRegister::Vec Regs;
unsigned Weight;
CodeGenRegister::RegUnitList SingularDeterminants;
UberRegSet(): Weight(0) {}
};
} // namespace
// Partition registers into UberRegSets, where each set is the transitive
// closure of the union of overlapping register classes.
//
// UberRegSets[0] is a special non-allocatable set.
static void computeUberSets(std::vector<UberRegSet> &UberSets,
std::vector<UberRegSet*> &RegSets,
CodeGenRegBank &RegBank) {
const auto &Registers = RegBank.getRegisters();
// The Register EnumValue is one greater than its index into Registers.
assert(Registers.size() == Registers.back().EnumValue &&
"register enum value mismatch");
// For simplicitly make the SetID the same as EnumValue.
IntEqClasses UberSetIDs(Registers.size()+1);
std::set<unsigned> AllocatableRegs;
for (auto &RegClass : RegBank.getRegClasses()) {
if (!RegClass.Allocatable)
continue;
const CodeGenRegister::Vec &Regs = RegClass.getMembers();
if (Regs.empty())
continue;
unsigned USetID = UberSetIDs.findLeader((*Regs.begin())->EnumValue);
assert(USetID && "register number 0 is invalid");
AllocatableRegs.insert((*Regs.begin())->EnumValue);
for (auto I = std::next(Regs.begin()), E = Regs.end(); I != E; ++I) {
AllocatableRegs.insert((*I)->EnumValue);
UberSetIDs.join(USetID, (*I)->EnumValue);
}
}
// Combine non-allocatable regs.
for (const auto &Reg : Registers) {
unsigned RegNum = Reg.EnumValue;
if (AllocatableRegs.count(RegNum))
continue;
UberSetIDs.join(0, RegNum);
}
UberSetIDs.compress();
// Make the first UberSet a special unallocatable set.
unsigned ZeroID = UberSetIDs[0];
// Insert Registers into the UberSets formed by union-find.
// Do not resize after this.
UberSets.resize(UberSetIDs.getNumClasses());
unsigned i = 0;
for (const CodeGenRegister &Reg : Registers) {
unsigned USetID = UberSetIDs[Reg.EnumValue];
if (!USetID)
USetID = ZeroID;
else if (USetID == ZeroID)
USetID = 0;
UberRegSet *USet = &UberSets[USetID];
USet->Regs.push_back(&Reg);
sortAndUniqueRegisters(USet->Regs);
RegSets[i++] = USet;
}
}
// Recompute each UberSet weight after changing unit weights.
static void computeUberWeights(std::vector<UberRegSet> &UberSets,
CodeGenRegBank &RegBank) {
// Skip the first unallocatable set.
for (std::vector<UberRegSet>::iterator I = std::next(UberSets.begin()),
E = UberSets.end(); I != E; ++I) {
// Initialize all unit weights in this set, and remember the max units/reg.
const CodeGenRegister *Reg = nullptr;
unsigned MaxWeight = 0, Weight = 0;
for (RegUnitIterator UnitI(I->Regs); UnitI.isValid(); ++UnitI) {
if (Reg != UnitI.getReg()) {
if (Weight > MaxWeight)
MaxWeight = Weight;
Reg = UnitI.getReg();
Weight = 0;
}
unsigned UWeight = RegBank.getRegUnit(*UnitI).Weight;
if (!UWeight) {
UWeight = 1;
RegBank.increaseRegUnitWeight(*UnitI, UWeight);
}
Weight += UWeight;
}
if (Weight > MaxWeight)
MaxWeight = Weight;
if (I->Weight != MaxWeight) {
DEBUG(
dbgs() << "UberSet " << I - UberSets.begin() << " Weight " << MaxWeight;
for (auto &Unit : I->Regs)
dbgs() << " " << Unit->getName();
dbgs() << "\n");
// Update the set weight.
I->Weight = MaxWeight;
}
// Find singular determinants.
for (const auto R : I->Regs) {
if (R->getRegUnits().count() == 1 && R->getWeight(RegBank) == I->Weight) {
I->SingularDeterminants |= R->getRegUnits();
}
}
}
}
// normalizeWeight is a computeRegUnitWeights helper that adjusts the weight of
// a register and its subregisters so that they have the same weight as their
// UberSet. Self-recursion processes the subregister tree in postorder so
// subregisters are normalized first.
//
// Side effects:
// - creates new adopted register units
// - causes superregisters to inherit adopted units
// - increases the weight of "singular" units
// - induces recomputation of UberWeights.
static bool normalizeWeight(CodeGenRegister *Reg,
std::vector<UberRegSet> &UberSets,
std::vector<UberRegSet*> &RegSets,
SparseBitVector<> &NormalRegs,
CodeGenRegister::RegUnitList &NormalUnits,
CodeGenRegBank &RegBank) {
if (NormalRegs.test(Reg->EnumValue))
return false;
NormalRegs.set(Reg->EnumValue);
bool Changed = false;
const CodeGenRegister::SubRegMap &SRM = Reg->getSubRegs();
for (CodeGenRegister::SubRegMap::const_iterator SRI = SRM.begin(),
SRE = SRM.end(); SRI != SRE; ++SRI) {
if (SRI->second == Reg)
continue; // self-cycles happen
Changed |= normalizeWeight(SRI->second, UberSets, RegSets,
NormalRegs, NormalUnits, RegBank);
}
// Postorder register normalization.
// Inherit register units newly adopted by subregisters.
if (Reg->inheritRegUnits(RegBank))
computeUberWeights(UberSets, RegBank);
// Check if this register is too skinny for its UberRegSet.
UberRegSet *UberSet = RegSets[RegBank.getRegIndex(Reg)];
unsigned RegWeight = Reg->getWeight(RegBank);
if (UberSet->Weight > RegWeight) {
// A register unit's weight can be adjusted only if it is the singular unit
// for this register, has not been used to normalize a subregister's set,
// and has not already been used to singularly determine this UberRegSet.
unsigned AdjustUnit = *Reg->getRegUnits().begin();
if (Reg->getRegUnits().count() != 1
|| hasRegUnit(NormalUnits, AdjustUnit)
|| hasRegUnit(UberSet->SingularDeterminants, AdjustUnit)) {
// We don't have an adjustable unit, so adopt a new one.
AdjustUnit = RegBank.newRegUnit(UberSet->Weight - RegWeight);
Reg->adoptRegUnit(AdjustUnit);
// Adopting a unit does not immediately require recomputing set weights.
}
else {
// Adjust the existing single unit.
RegBank.increaseRegUnitWeight(AdjustUnit, UberSet->Weight - RegWeight);
// The unit may be shared among sets and registers within this set.
computeUberWeights(UberSets, RegBank);
}
Changed = true;
}
// Mark these units normalized so superregisters can't change their weights.
NormalUnits |= Reg->getRegUnits();
return Changed;
}
// Compute a weight for each register unit created during getSubRegs.
//
// The goal is that two registers in the same class will have the same weight,
// where each register's weight is defined as sum of its units' weights.
void CodeGenRegBank::computeRegUnitWeights() {
std::vector<UberRegSet> UberSets;
std::vector<UberRegSet*> RegSets(Registers.size());
computeUberSets(UberSets, RegSets, *this);
// UberSets and RegSets are now immutable.
computeUberWeights(UberSets, *this);
// Iterate over each Register, normalizing the unit weights until reaching
// a fix point.
unsigned NumIters = 0;
for (bool Changed = true; Changed; ++NumIters) {
assert(NumIters <= NumNativeRegUnits && "Runaway register unit weights");
Changed = false;
for (auto &Reg : Registers) {
CodeGenRegister::RegUnitList NormalUnits;
SparseBitVector<> NormalRegs;
Changed |= normalizeWeight(&Reg, UberSets, RegSets, NormalRegs,
NormalUnits, *this);
}
}
}
// Find a set in UniqueSets with the same elements as Set.
// Return an iterator into UniqueSets.
static std::vector<RegUnitSet>::const_iterator
findRegUnitSet(const std::vector<RegUnitSet> &UniqueSets,
const RegUnitSet &Set) {
std::vector<RegUnitSet>::const_iterator
I = UniqueSets.begin(), E = UniqueSets.end();
for(;I != E; ++I) {
if (I->Units == Set.Units)
break;
}
return I;
}
// Return true if the RUSubSet is a subset of RUSuperSet.
static bool isRegUnitSubSet(const std::vector<unsigned> &RUSubSet,
const std::vector<unsigned> &RUSuperSet) {
return std::includes(RUSuperSet.begin(), RUSuperSet.end(),
RUSubSet.begin(), RUSubSet.end());
}
/// Iteratively prune unit sets. Prune subsets that are close to the superset,
/// but with one or two registers removed. We occasionally have registers like
/// APSR and PC thrown in with the general registers. We also see many
/// special-purpose register subsets, such as tail-call and Thumb
/// encodings. Generating all possible overlapping sets is combinatorial and
/// overkill for modeling pressure. Ideally we could fix this statically in
/// tablegen by (1) having the target define register classes that only include
/// the allocatable registers and marking other classes as non-allocatable and
/// (2) having a way to mark special purpose classes as "don't-care" classes for
/// the purpose of pressure. However, we make an attempt to handle targets that
/// are not nicely defined by merging nearly identical register unit sets
/// statically. This generates smaller tables. Then, dynamically, we adjust the
/// set limit by filtering the reserved registers.
///
/// Merge sets only if the units have the same weight. For example, on ARM,
/// Q-tuples with ssub index 0 include all S regs but also include D16+. We
/// should not expand the S set to include D regs.
void CodeGenRegBank::pruneUnitSets() {
assert(RegClassUnitSets.empty() && "this invalidates RegClassUnitSets");
// Form an equivalence class of UnitSets with no significant difference.
std::vector<unsigned> SuperSetIDs;
for (unsigned SubIdx = 0, EndIdx = RegUnitSets.size();
SubIdx != EndIdx; ++SubIdx) {
const RegUnitSet &SubSet = RegUnitSets[SubIdx];
unsigned SuperIdx = 0;
for (; SuperIdx != EndIdx; ++SuperIdx) {
if (SuperIdx == SubIdx)
continue;
unsigned UnitWeight = RegUnits[SubSet.Units[0]].Weight;
const RegUnitSet &SuperSet = RegUnitSets[SuperIdx];
if (isRegUnitSubSet(SubSet.Units, SuperSet.Units)
&& (SubSet.Units.size() + 3 > SuperSet.Units.size())
&& UnitWeight == RegUnits[SuperSet.Units[0]].Weight
&& UnitWeight == RegUnits[SuperSet.Units.back()].Weight) {
DEBUG(dbgs() << "UnitSet " << SubIdx << " subsumed by " << SuperIdx
<< "\n");
break;
}
}
if (SuperIdx == EndIdx)
SuperSetIDs.push_back(SubIdx);
}
// Populate PrunedUnitSets with each equivalence class's superset.
std::vector<RegUnitSet> PrunedUnitSets(SuperSetIDs.size());
for (unsigned i = 0, e = SuperSetIDs.size(); i != e; ++i) {
unsigned SuperIdx = SuperSetIDs[i];
PrunedUnitSets[i].Name = RegUnitSets[SuperIdx].Name;
PrunedUnitSets[i].Units.swap(RegUnitSets[SuperIdx].Units);
}
RegUnitSets.swap(PrunedUnitSets);
}
// Create a RegUnitSet for each RegClass that contains all units in the class
// including adopted units that are necessary to model register pressure. Then
// iteratively compute RegUnitSets such that the union of any two overlapping
// RegUnitSets is repreresented.
//
// RegisterInfoEmitter will map each RegClass to its RegUnitClass and any
// RegUnitSet that is a superset of that RegUnitClass.
void CodeGenRegBank::computeRegUnitSets() {
assert(RegUnitSets.empty() && "dirty RegUnitSets");
// Compute a unique RegUnitSet for each RegClass.
auto &RegClasses = getRegClasses();
for (auto &RC : RegClasses) {
if (!RC.Allocatable)
continue;
// Speculatively grow the RegUnitSets to hold the new set.
RegUnitSets.resize(RegUnitSets.size() + 1);
RegUnitSets.back().Name = RC.getName();
// Compute a sorted list of units in this class.
RC.buildRegUnitSet(RegUnitSets.back().Units);
// Find an existing RegUnitSet.
std::vector<RegUnitSet>::const_iterator SetI =
findRegUnitSet(RegUnitSets, RegUnitSets.back());
if (SetI != std::prev(RegUnitSets.end()))
RegUnitSets.pop_back();
}
DEBUG(dbgs() << "\nBefore pruning:\n";
for (unsigned USIdx = 0, USEnd = RegUnitSets.size();
USIdx < USEnd; ++USIdx) {
dbgs() << "UnitSet " << USIdx << " " << RegUnitSets[USIdx].Name
<< ":";
for (auto &U : RegUnitSets[USIdx].Units)
dbgs() << " " << RegUnits[U].Roots[0]->getName();
dbgs() << "\n";
});
// Iteratively prune unit sets.
pruneUnitSets();
DEBUG(dbgs() << "\nBefore union:\n";
for (unsigned USIdx = 0, USEnd = RegUnitSets.size();
USIdx < USEnd; ++USIdx) {
dbgs() << "UnitSet " << USIdx << " " << RegUnitSets[USIdx].Name
<< ":";
for (auto &U : RegUnitSets[USIdx].Units)
dbgs() << " " << RegUnits[U].Roots[0]->getName();
dbgs() << "\n";
}
dbgs() << "\nUnion sets:\n");
// Iterate over all unit sets, including new ones added by this loop.
unsigned NumRegUnitSubSets = RegUnitSets.size();
for (unsigned Idx = 0, EndIdx = RegUnitSets.size(); Idx != EndIdx; ++Idx) {
// In theory, this is combinatorial. In practice, it needs to be bounded
// by a small number of sets for regpressure to be efficient.
// If the assert is hit, we need to implement pruning.
assert(Idx < (2*NumRegUnitSubSets) && "runaway unit set inference");
// Compare new sets with all original classes.
for (unsigned SearchIdx = (Idx >= NumRegUnitSubSets) ? 0 : Idx+1;
SearchIdx != EndIdx; ++SearchIdx) {
std::set<unsigned> Intersection;
std::set_intersection(RegUnitSets[Idx].Units.begin(),
RegUnitSets[Idx].Units.end(),
RegUnitSets[SearchIdx].Units.begin(),
RegUnitSets[SearchIdx].Units.end(),
std::inserter(Intersection, Intersection.begin()));
if (Intersection.empty())
continue;
// Speculatively grow the RegUnitSets to hold the new set.
RegUnitSets.resize(RegUnitSets.size() + 1);
RegUnitSets.back().Name =
RegUnitSets[Idx].Name + "+" + RegUnitSets[SearchIdx].Name;
std::set_union(RegUnitSets[Idx].Units.begin(),
RegUnitSets[Idx].Units.end(),
RegUnitSets[SearchIdx].Units.begin(),
RegUnitSets[SearchIdx].Units.end(),
std::inserter(RegUnitSets.back().Units,
RegUnitSets.back().Units.begin()));
// Find an existing RegUnitSet, or add the union to the unique sets.
std::vector<RegUnitSet>::const_iterator SetI =
findRegUnitSet(RegUnitSets, RegUnitSets.back());
if (SetI != std::prev(RegUnitSets.end()))
RegUnitSets.pop_back();
else {
DEBUG(dbgs() << "UnitSet " << RegUnitSets.size()-1
<< " " << RegUnitSets.back().Name << ":";
for (auto &U : RegUnitSets.back().Units)
dbgs() << " " << RegUnits[U].Roots[0]->getName();
dbgs() << "\n";);
}
}
}
// Iteratively prune unit sets after inferring supersets.
pruneUnitSets();
DEBUG(dbgs() << "\n";
for (unsigned USIdx = 0, USEnd = RegUnitSets.size();
USIdx < USEnd; ++USIdx) {
dbgs() << "UnitSet " << USIdx << " " << RegUnitSets[USIdx].Name
<< ":";
for (auto &U : RegUnitSets[USIdx].Units)
dbgs() << " " << RegUnits[U].Roots[0]->getName();
dbgs() << "\n";
});
// For each register class, list the UnitSets that are supersets.
RegClassUnitSets.resize(RegClasses.size());
int RCIdx = -1;
for (auto &RC : RegClasses) {
++RCIdx;
if (!RC.Allocatable)
continue;
// Recompute the sorted list of units in this class.
std::vector<unsigned> RCRegUnits;
RC.buildRegUnitSet(RCRegUnits);
// Don't increase pressure for unallocatable regclasses.
if (RCRegUnits.empty())
continue;
DEBUG(dbgs() << "RC " << RC.getName() << " Units: \n";
for (auto &U : RCRegUnits)
dbgs() << RegUnits[U].getRoots()[0]->getName() << " ";
dbgs() << "\n UnitSetIDs:");
// Find all supersets.
for (unsigned USIdx = 0, USEnd = RegUnitSets.size();
USIdx != USEnd; ++USIdx) {
if (isRegUnitSubSet(RCRegUnits, RegUnitSets[USIdx].Units)) {
DEBUG(dbgs() << " " << USIdx);
RegClassUnitSets[RCIdx].push_back(USIdx);
}
}
DEBUG(dbgs() << "\n");
assert(!RegClassUnitSets[RCIdx].empty() && "missing unit set for regclass");
}
// For each register unit, ensure that we have the list of UnitSets that
// contain the unit. Normally, this matches an existing list of UnitSets for a
// register class. If not, we create a new entry in RegClassUnitSets as a
// "fake" register class.
for (unsigned UnitIdx = 0, UnitEnd = NumNativeRegUnits;
UnitIdx < UnitEnd; ++UnitIdx) {
std::vector<unsigned> RUSets;
for (unsigned i = 0, e = RegUnitSets.size(); i != e; ++i) {
RegUnitSet &RUSet = RegUnitSets[i];
if (std::find(RUSet.Units.begin(), RUSet.Units.end(), UnitIdx)
== RUSet.Units.end())
continue;
RUSets.push_back(i);
}
unsigned RCUnitSetsIdx = 0;
for (unsigned e = RegClassUnitSets.size();
RCUnitSetsIdx != e; ++RCUnitSetsIdx) {
if (RegClassUnitSets[RCUnitSetsIdx] == RUSets) {
break;
}
}
RegUnits[UnitIdx].RegClassUnitSetsIdx = RCUnitSetsIdx;
if (RCUnitSetsIdx == RegClassUnitSets.size()) {
// Create a new list of UnitSets as a "fake" register class.
RegClassUnitSets.resize(RCUnitSetsIdx + 1);
RegClassUnitSets[RCUnitSetsIdx].swap(RUSets);
}
}
}
void CodeGenRegBank::computeRegUnitLaneMasks() {
for (auto &Register : Registers) {
// Create an initial lane mask for all register units.
const auto &RegUnits = Register.getRegUnits();
CodeGenRegister::RegUnitLaneMaskList RegUnitLaneMasks(RegUnits.count(), 0);
// Iterate through SubRegisters.
typedef CodeGenRegister::SubRegMap SubRegMap;
const SubRegMap &SubRegs = Register.getSubRegs();
for (SubRegMap::const_iterator S = SubRegs.begin(),
SE = SubRegs.end(); S != SE; ++S) {
CodeGenRegister *SubReg = S->second;
// Ignore non-leaf subregisters, their lane masks are fully covered by
// the leaf subregisters anyway.
if (SubReg->getSubRegs().size() != 0)
continue;
CodeGenSubRegIndex *SubRegIndex = S->first;
const CodeGenRegister *SubRegister = S->second;
unsigned LaneMask = SubRegIndex->LaneMask;
// Distribute LaneMask to Register Units touched.
for (unsigned SUI : SubRegister->getRegUnits()) {
bool Found = false;
unsigned u = 0;
for (unsigned RU : RegUnits) {
if (SUI == RU) {
RegUnitLaneMasks[u] |= LaneMask;
assert(!Found);
Found = true;
}
++u;
}
(void)Found;
assert(Found);
}
}
Register.setRegUnitLaneMasks(RegUnitLaneMasks);
}
}
void CodeGenRegBank::computeDerivedInfo() {
computeComposites();
computeSubRegLaneMasks();
// Compute a weight for each register unit created during getSubRegs.
// This may create adopted register units (with unit # >= NumNativeRegUnits).
computeRegUnitWeights();
// Compute a unique set of RegUnitSets. One for each RegClass and inferred
// supersets for the union of overlapping sets.
computeRegUnitSets();
computeRegUnitLaneMasks();
// Compute register class HasDisjunctSubRegs flag.
for (CodeGenRegisterClass &RC : RegClasses) {
RC.HasDisjunctSubRegs = false;
for (const CodeGenRegister *Reg : RC.getMembers())
RC.HasDisjunctSubRegs |= Reg->HasDisjunctSubRegs;
}
// Get the weight of each set.
for (unsigned Idx = 0, EndIdx = RegUnitSets.size(); Idx != EndIdx; ++Idx)
RegUnitSets[Idx].Weight = getRegUnitSetWeight(RegUnitSets[Idx].Units);
// Find the order of each set.
RegUnitSetOrder.reserve(RegUnitSets.size());
for (unsigned Idx = 0, EndIdx = RegUnitSets.size(); Idx != EndIdx; ++Idx)
RegUnitSetOrder.push_back(Idx);
std::stable_sort(RegUnitSetOrder.begin(), RegUnitSetOrder.end(),
[this](unsigned ID1, unsigned ID2) {
return getRegPressureSet(ID1).Units.size() <
getRegPressureSet(ID2).Units.size();
});
for (unsigned Idx = 0, EndIdx = RegUnitSets.size(); Idx != EndIdx; ++Idx) {
RegUnitSets[RegUnitSetOrder[Idx]].Order = Idx;
}
}
//
// Synthesize missing register class intersections.
//
// Make sure that sub-classes of RC exists such that getCommonSubClass(RC, X)
// returns a maximal register class for all X.
//
void CodeGenRegBank::inferCommonSubClass(CodeGenRegisterClass *RC) {
assert(!RegClasses.empty());
// Stash the iterator to the last element so that this loop doesn't visit
// elements added by the getOrCreateSubClass call within it.
for (auto I = RegClasses.begin(), E = std::prev(RegClasses.end());
I != std::next(E); ++I) {
CodeGenRegisterClass *RC1 = RC;
CodeGenRegisterClass *RC2 = &*I;
if (RC1 == RC2)
continue;
// Compute the set intersection of RC1 and RC2.
const CodeGenRegister::Vec &Memb1 = RC1->getMembers();
const CodeGenRegister::Vec &Memb2 = RC2->getMembers();
CodeGenRegister::Vec Intersection;
std::set_intersection(
Memb1.begin(), Memb1.end(), Memb2.begin(), Memb2.end(),
std::inserter(Intersection, Intersection.begin()), deref<llvm::less>());
// Skip disjoint class pairs.
if (Intersection.empty())
continue;
// If RC1 and RC2 have different spill sizes or alignments, use the
// larger size for sub-classing. If they are equal, prefer RC1.
if (RC2->SpillSize > RC1->SpillSize ||
(RC2->SpillSize == RC1->SpillSize &&
RC2->SpillAlignment > RC1->SpillAlignment))
std::swap(RC1, RC2);
getOrCreateSubClass(RC1, &Intersection,
RC1->getName() + "_and_" + RC2->getName());
}
}
//
// Synthesize missing sub-classes for getSubClassWithSubReg().
//
// Make sure that the set of registers in RC with a given SubIdx sub-register
// form a register class. Update RC->SubClassWithSubReg.
//
void CodeGenRegBank::inferSubClassWithSubReg(CodeGenRegisterClass *RC) {
// Map SubRegIndex to set of registers in RC supporting that SubRegIndex.
typedef std::map<const CodeGenSubRegIndex *, CodeGenRegister::Vec,
deref<llvm::less>> SubReg2SetMap;
// Compute the set of registers supporting each SubRegIndex.
SubReg2SetMap SRSets;
for (const auto R : RC->getMembers()) {
const CodeGenRegister::SubRegMap &SRM = R->getSubRegs();
for (CodeGenRegister::SubRegMap::const_iterator I = SRM.begin(),
E = SRM.end(); I != E; ++I)
SRSets[I->first].push_back(R);
}
for (auto I : SRSets)
sortAndUniqueRegisters(I.second);
// Find matching classes for all SRSets entries. Iterate in SubRegIndex
// numerical order to visit synthetic indices last.
for (const auto &SubIdx : SubRegIndices) {
SubReg2SetMap::const_iterator I = SRSets.find(&SubIdx);
// Unsupported SubRegIndex. Skip it.
if (I == SRSets.end())
continue;
// In most cases, all RC registers support the SubRegIndex.
if (I->second.size() == RC->getMembers().size()) {
RC->setSubClassWithSubReg(&SubIdx, RC);
continue;
}
// This is a real subset. See if we have a matching class.
CodeGenRegisterClass *SubRC =
getOrCreateSubClass(RC, &I->second,
RC->getName() + "_with_" + I->first->getName());
RC->setSubClassWithSubReg(&SubIdx, SubRC);
}
}
//
// Synthesize missing sub-classes of RC for getMatchingSuperRegClass().
//
// Create sub-classes of RC such that getMatchingSuperRegClass(RC, SubIdx, X)
// has a maximal result for any SubIdx and any X >= FirstSubRegRC.
//
void CodeGenRegBank::inferMatchingSuperRegClass(CodeGenRegisterClass *RC,
std::list<CodeGenRegisterClass>::iterator FirstSubRegRC) {
SmallVector<std::pair<const CodeGenRegister*,
const CodeGenRegister*>, 16> SSPairs;
BitVector TopoSigs(getNumTopoSigs());
// Iterate in SubRegIndex numerical order to visit synthetic indices last.
for (auto &SubIdx : SubRegIndices) {
// Skip indexes that aren't fully supported by RC's registers. This was
// computed by inferSubClassWithSubReg() above which should have been
// called first.
if (RC->getSubClassWithSubReg(&SubIdx) != RC)
continue;
// Build list of (Super, Sub) pairs for this SubIdx.
SSPairs.clear();
TopoSigs.reset();
for (const auto Super : RC->getMembers()) {
const CodeGenRegister *Sub = Super->getSubRegs().find(&SubIdx)->second;
assert(Sub && "Missing sub-register");
SSPairs.push_back(std::make_pair(Super, Sub));
TopoSigs.set(Sub->getTopoSig());
}
// Iterate over sub-register class candidates. Ignore classes created by
// this loop. They will never be useful.
// Store an iterator to the last element (not end) so that this loop doesn't
// visit newly inserted elements.
assert(!RegClasses.empty());
for (auto I = FirstSubRegRC, E = std::prev(RegClasses.end());
I != std::next(E); ++I) {
CodeGenRegisterClass &SubRC = *I;
// Topological shortcut: SubRC members have the wrong shape.
if (!TopoSigs.anyCommon(SubRC.getTopoSigs()))
continue;
// Compute the subset of RC that maps into SubRC.
CodeGenRegister::Vec SubSetVec;
for (unsigned i = 0, e = SSPairs.size(); i != e; ++i)
if (SubRC.contains(SSPairs[i].second))
SubSetVec.push_back(SSPairs[i].first);
if (SubSetVec.empty())
continue;
// RC injects completely into SubRC.
sortAndUniqueRegisters(SubSetVec);
if (SubSetVec.size() == SSPairs.size()) {
SubRC.addSuperRegClass(&SubIdx, RC);
continue;
}
// Only a subset of RC maps into SubRC. Make sure it is represented by a
// class.
getOrCreateSubClass(RC, &SubSetVec, RC->getName() + "_with_" +
SubIdx.getName() + "_in_" +
SubRC.getName());
}
}
}
//
// Infer missing register classes.
//
void CodeGenRegBank::computeInferredRegisterClasses() {
assert(!RegClasses.empty());
// When this function is called, the register classes have not been sorted
// and assigned EnumValues yet. That means getSubClasses(),
// getSuperClasses(), and hasSubClass() functions are defunct.
// Use one-before-the-end so it doesn't move forward when new elements are
// added.
auto FirstNewRC = std::prev(RegClasses.end());
// Visit all register classes, including the ones being added by the loop.
// Watch out for iterator invalidation here.
for (auto I = RegClasses.begin(), E = RegClasses.end(); I != E; ++I) {
CodeGenRegisterClass *RC = &*I;
// Synthesize answers for getSubClassWithSubReg().
inferSubClassWithSubReg(RC);
// Synthesize answers for getCommonSubClass().
inferCommonSubClass(RC);
// Synthesize answers for getMatchingSuperRegClass().
inferMatchingSuperRegClass(RC);
// New register classes are created while this loop is running, and we need
// to visit all of them. I particular, inferMatchingSuperRegClass needs
// to match old super-register classes with sub-register classes created
// after inferMatchingSuperRegClass was called. At this point,
// inferMatchingSuperRegClass has checked SuperRC = [0..rci] with SubRC =
// [0..FirstNewRC). We need to cover SubRC = [FirstNewRC..rci].
if (I == FirstNewRC) {
auto NextNewRC = std::prev(RegClasses.end());
for (auto I2 = RegClasses.begin(), E2 = std::next(FirstNewRC); I2 != E2;
++I2)
inferMatchingSuperRegClass(&*I2, E2);
FirstNewRC = NextNewRC;
}
}
}
/// getRegisterClassForRegister - Find the register class that contains the
/// specified physical register. If the register is not in a register class,
/// return null. If the register is in multiple classes, and the classes have a
/// superset-subset relationship and the same set of types, return the
/// superclass. Otherwise return null.
const CodeGenRegisterClass*
CodeGenRegBank::getRegClassForRegister(Record *R) {
const CodeGenRegister *Reg = getReg(R);
const CodeGenRegisterClass *FoundRC = nullptr;
for (const auto &RC : getRegClasses()) {
if (!RC.contains(Reg))
continue;
// If this is the first class that contains the register,
// make a note of it and go on to the next class.
if (!FoundRC) {
FoundRC = &RC;
continue;
}
// If a register's classes have different types, return null.
if (RC.getValueTypes() != FoundRC->getValueTypes())
return nullptr;
// Check to see if the previously found class that contains
// the register is a subclass of the current class. If so,
// prefer the superclass.
if (RC.hasSubClass(FoundRC)) {
FoundRC = &RC;
continue;
}
// Check to see if the previously found class that contains
// the register is a superclass of the current class. If so,
// prefer the superclass.
if (FoundRC->hasSubClass(&RC))
continue;
// Multiple classes, and neither is a superclass of the other.
// Return null.
return nullptr;
}
return FoundRC;
}
BitVector CodeGenRegBank::computeCoveredRegisters(ArrayRef<Record*> Regs) {
SetVector<const CodeGenRegister*> Set;
// First add Regs with all sub-registers.
for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
CodeGenRegister *Reg = getReg(Regs[i]);
if (Set.insert(Reg))
// Reg is new, add all sub-registers.
// The pre-ordering is not important here.
Reg->addSubRegsPreOrder(Set, *this);
}
// Second, find all super-registers that are completely covered by the set.
for (unsigned i = 0; i != Set.size(); ++i) {
const CodeGenRegister::SuperRegList &SR = Set[i]->getSuperRegs();
for (unsigned j = 0, e = SR.size(); j != e; ++j) {
const CodeGenRegister *Super = SR[j];
if (!Super->CoveredBySubRegs || Set.count(Super))
continue;
// This new super-register is covered by its sub-registers.
bool AllSubsInSet = true;
const CodeGenRegister::SubRegMap &SRM = Super->getSubRegs();
for (CodeGenRegister::SubRegMap::const_iterator I = SRM.begin(),
E = SRM.end(); I != E; ++I)
if (!Set.count(I->second)) {
AllSubsInSet = false;
break;
}
// All sub-registers in Set, add Super as well.
// We will visit Super later to recheck its super-registers.
if (AllSubsInSet)
Set.insert(Super);
}
}
// Convert to BitVector.
BitVector BV(Registers.size() + 1);
for (unsigned i = 0, e = Set.size(); i != e; ++i)
BV.set(Set[i]->EnumValue);
return BV;
}