//===- 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/TableGen/Error.h"
#include "llvm/ADT/IntEqClasses.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// CodeGenSubRegIndex
//===----------------------------------------------------------------------===//
CodeGenSubRegIndex::CodeGenSubRegIndex(Record *R, unsigned Enum)
: TheDef(R), EnumValue(Enum) {
Name = R->getName();
if (R->getValue("Namespace"))
Namespace = R->getValueAsString("Namespace");
}
CodeGenSubRegIndex::CodeGenSubRegIndex(StringRef N, StringRef Nspace,
unsigned Enum)
: TheDef(0), Name(N), Namespace(Nspace), EnumValue(Enum) {
}
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)
throw TGError(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)
throw TGError(TheDef->getLoc(), "Ambiguous ComposedOf entries");
}
std::vector<Record*> Parts =
TheDef->getValueAsListOfDefs("CoveringSubRegIndices");
if (!Parts.empty()) {
if (Parts.size() < 2)
throw TGError(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);
}
}
void CodeGenSubRegIndex::cleanComposites() {
// Clean out redundant mappings of the form this+X -> X.
for (CompMap::iterator i = Composed.begin(), e = Composed.end(); i != e;) {
CompMap::iterator j = i;
++i;
if (j->first == j->second)
Composed.erase(j);
}
}
//===----------------------------------------------------------------------===//
// CodeGenRegister
//===----------------------------------------------------------------------===//
CodeGenRegister::CodeGenRegister(Record *R, unsigned Enum)
: TheDef(R),
EnumValue(Enum),
CostPerUse(R->getValueAsInt("CostPerUse")),
CoveredBySubRegs(R->getValueAsBit("CoveredBySubRegs")),
NumNativeRegUnits(0),
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())
throw TGError(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 {
return TheDef->getName();
}
namespace {
// Iterate over all register units in a set of registers.
class RegUnitIterator {
CodeGenRegister::Set::const_iterator RegI, RegE;
CodeGenRegister::RegUnitList::const_iterator UnitI, UnitE;
public:
RegUnitIterator(const CodeGenRegister::Set &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
// Merge two RegUnitLists maintaining the order and removing duplicates.
// Overwrites MergedRU in the process.
static void mergeRegUnits(CodeGenRegister::RegUnitList &MergedRU,
const CodeGenRegister::RegUnitList &RRU) {
CodeGenRegister::RegUnitList LRU = MergedRU;
MergedRU.clear();
std::set_union(LRU.begin(), LRU.end(), RRU.begin(), RRU.end(),
std::back_inserter(MergedRU));
}
// Return true of this unit appears in RegUnits.
static bool hasRegUnit(CodeGenRegister::RegUnitList &RegUnits, unsigned Unit) {
return std::count(RegUnits.begin(), RegUnits.end(), Unit);
}
// Inherit register units from subregisters.
// Return true if the RegUnits changed.
bool CodeGenRegister::inheritRegUnits(CodeGenRegBank &RegBank) {
unsigned OldNumUnits = RegUnits.size();
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.
mergeRegUnits(RegUnits, SR->RegUnits);
}
return OldNumUnits != RegUnits.size();
}
const CodeGenRegister::SubRegMap &
CodeGenRegister::computeSubRegs(CodeGenRegBank &RegBank) {
// Only compute this map once.
if (SubRegsComplete)
return SubRegs;
SubRegsComplete = true;
// 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)
throw TGError(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);
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();
throw TGError(Loc, "Register " + getName() +
" has itself as a sub-register");
}
// 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();
throw TGError(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];
// Explicit sub-registers are usually disjoint, so this is a good way of
// computing the union. We may pick up a few duplicates that will be
// eliminated below.
unsigned N = RegUnits.size();
RegUnits.append(SR->RegUnits.begin(), SR->RegUnits.end());
std::inplace_merge(RegUnits.begin(), RegUnits.begin() + N, RegUnits.end());
}
RegUnits.erase(std::unique(RegUnits.begin(), RegUnits.end()), RegUnits.end());
// 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.push_back(Unit);
AR->RegUnits.push_back(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.push_back(RegBank.newRegUnit(this));
// We have now computed the native register units. More may be adopted later
// for balancing purposes.
NumNativeRegUnits = RegUnits.size();
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)
throw TGError(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);
}
// Compute overlapping registers.
//
// The standard set is all super-registers and all sub-registers, but the
// target description can add arbitrary overlapping registers via the 'Aliases'
// field. This complicates things, but we can compute overlapping sets using
// the following rules:
//
// 1. The relation overlap(A, B) is reflexive and symmetric but not transitive.
//
// 2. overlap(A, B) implies overlap(A, S) for all S in supers(B).
//
// Alternatively:
//
// overlap(A, B) iff there exists:
// A' in { A, subregs(A) } and B' in { B, subregs(B) } such that:
// A' = B' or A' in aliases(B') or B' in aliases(A').
//
// Here subregs(A) is the full flattened sub-register set returned by
// A.getSubRegs() while aliases(A) is simply the special 'Aliases' field in the
// description of register A.
//
// This also implies that registers with a common sub-register are considered
// overlapping. This can happen when forming register pairs:
//
// P0 = (R0, R1)
// P1 = (R1, R2)
// P2 = (R2, R3)
//
// In this case, we will infer an overlap between P0 and P1 because of the
// shared sub-register R1. There is no overlap between P0 and P2.
//
void CodeGenRegister::computeOverlaps(CodeGenRegister::Set &Overlaps,
const CodeGenRegBank &RegBank) const {
assert(!RegUnits.empty() && "Compute register units before overlaps.");
// Register units are assigned such that the overlapping registers are the
// super-registers of the root registers of the register units.
for (unsigned rui = 0, rue = RegUnits.size(); rui != rue; ++rui) {
const RegUnit &RU = RegBank.getRegUnit(RegUnits[rui]);
ArrayRef<const CodeGenRegister*> Roots = RU.getRoots();
for (unsigned ri = 0, re = Roots.size(); ri != re; ++ri) {
const CodeGenRegister *Root = Roots[ri];
Overlaps.insert(Root);
ArrayRef<const CodeGenRegister*> Supers = Root->getSuperRegs();
Overlaps.insert(Supers.begin(), Supers.end());
}
}
}
// Get the sum of this register's unit weights.
unsigned CodeGenRegister::getWeight(const CodeGenRegBank &RegBank) const {
unsigned Weight = 0;
for (RegUnitList::const_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) {
std::vector<Record*> Indices = Def->getValueAsListOfDefs("SubRegIndices");
unsigned Dim = Indices.size();
ListInit *SubRegs = Def->getValueAsListInit("SubRegs");
if (Dim != SubRegs->getSize())
throw TGError(Def->getLoc(), "SubRegIndices and SubRegs size mismatch");
if (Dim < 2)
throw TGError(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]);
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.
for (unsigned i = 0, e = Proto->getSuperClasses().size(); i != e; ++i)
NewReg->addSuperClass(Proto->getSuperClasses()[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
//===----------------------------------------------------------------------===//
CodeGenRegisterClass::CodeGenRegisterClass(CodeGenRegBank &RegBank, Record *R)
: TheDef(R),
Name(R->getName()),
TopoSigs(RegBank.getNumTopoSigs()),
EnumValue(-1) {
// 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"))
throw "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.insert(Reg);
TopoSigs.set(Reg->getTopoSig());
}
// 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);
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))
throw TGError(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 : EVT(VTs[0]).getSizeInBits();
SpillAlignment = R->getValueAsInt("Alignment");
CopyCost = R->getValueAsInt("CopyCost");
Allocatable = R->getValueAsBit("isAllocatable");
AltOrderSelect = R->getValueAsString("AltOrderSelect");
}
// 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(0),
Name(Name),
TopoSigs(RegBank.getNumTopoSigs()),
EnumValue(-1),
SpillSize(Props.SpillSize),
SpillAlignment(Props.SpillAlignment),
CopyCost(0),
Allocatable(true) {
for (CodeGenRegister::Set::iterator I = Members.begin(), E = Members.end();
I != E; ++I)
TopoSigs.set((*I)->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;
// 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 Members.count(Reg);
}
namespace llvm {
raw_ostream &operator<<(raw_ostream &OS, const CodeGenRegisterClass::Key &K) {
OS << "{ S=" << K.SpillSize << ", A=" << K.SpillAlignment;
for (CodeGenRegister::Set::const_iterator I = K.Members->begin(),
E = K.Members->end(); I != E; ++I)
OS << ", " << (*I)->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);
if (*Members != *B.Members)
return *Members < *B.Members;
if (SpillSize != B.SpillSize)
return SpillSize < B.SpillSize;
return SpillAlignment < 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(),
CodeGenRegister::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 int TopoOrderRC(const void *PA, const void *PB) {
const CodeGenRegisterClass *A = *(const CodeGenRegisterClass* const*)PA;
const CodeGenRegisterClass *B = *(const CodeGenRegisterClass* const*)PB;
if (A == B)
return 0;
// Order by ascending spill size.
if (A->SpillSize < B->SpillSize)
return -1;
if (A->SpillSize > B->SpillSize)
return 1;
// Order by ascending spill alignment.
if (A->SpillAlignment < B->SpillAlignment)
return -1;
if (A->SpillAlignment > B->SpillAlignment)
return 1;
// 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 -1;
if (A->getMembers().size() < B->getMembers().size())
return 1;
// Finally order by name as a tie breaker.
return StringRef(A->getName()).compare(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) {
ArrayRef<CodeGenRegisterClass*> RegClasses = RegBank.getRegClasses();
// Visit backwards so sub-classes are seen first.
for (unsigned rci = RegClasses.size(); rci; --rci) {
CodeGenRegisterClass &RC = *RegClasses[rci - 1];
RC.SubClasses.resize(RegClasses.size());
RC.SubClasses.set(RC.EnumValue);
// Normally, all subclasses have IDs >= rci, unless RC is part of a clique.
for (unsigned s = rci; s != RegClasses.size(); ++s) {
if (RC.SubClasses.test(s))
continue;
CodeGenRegisterClass *SubRC = RegClasses[s];
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 (unsigned s = rci - 1; s && testSubClass(&RC, RegClasses[s - 1]); --s)
RC.SubClasses.set(s - 1);
}
// Compute the SuperClasses lists from the SubClasses vectors.
for (unsigned rci = 0; rci != RegClasses.size(); ++rci) {
const BitVector &SC = RegClasses[rci]->getSubClasses();
for (int s = SC.find_first(); s >= 0; s = SC.find_next(s)) {
if (unsigned(s) == rci)
continue;
RegClasses[s]->SuperClasses.push_back(RegClasses[rci]);
}
}
// 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 (unsigned rci = 0; rci != RegClasses.size(); ++rci)
if (!RegClasses[rci]->getDef())
RegClasses[rci]->inheritProperties(RegBank);
}
void
CodeGenRegisterClass::getSuperRegClasses(CodeGenSubRegIndex *SubIdx,
BitVector &Out) const {
DenseMap<CodeGenSubRegIndex*,
SmallPtrSet<CodeGenRegisterClass*, 8> >::const_iterator
FindI = SuperRegClasses.find(SubIdx);
if (FindI == SuperRegClasses.end())
return;
for (SmallPtrSet<CodeGenRegisterClass*, 8>::const_iterator I =
FindI->second.begin(), E = FindI->second.end(); I != E; ++I)
Out.set((*I)->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 (unsigned i = 0, e = SubRegIndices.size(); i != e; ++i)
SubRegIndices[i]->updateComponents(*this);
// Read in the register definitions.
std::vector<Record*> Regs = Records.getAllDerivedDefinitions("Register");
std::sort(Regs.begin(), Regs.end(), LessRecord());
Registers.reserve(Regs.size());
// 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 (unsigned i = 0, e = Tups.size(); i != e; ++i) {
const std::vector<Record*> *TupRegs = Sets.expand(Tups[i]);
for (unsigned j = 0, je = TupRegs->size(); j != je; ++j)
getReg((*TupRegs)[j]);
}
// Now all the registers are known. Build the object graph of explicit
// register-register references.
for (unsigned i = 0, e = Registers.size(); i != e; ++i)
Registers[i]->buildObjectGraph(*this);
// Precompute all sub-register maps.
// This will create Composite entries for all inferred sub-register indices.
for (unsigned i = 0, e = Registers.size(); i != e; ++i)
Registers[i]->computeSubRegs(*this);
// Infer even more sub-registers by combining leading super-registers.
for (unsigned i = 0, e = Registers.size(); i != e; ++i)
if (Registers[i]->CoveredBySubRegs)
Registers[i]->computeSecondarySubRegs(*this);
// After the sub-register graph is complete, compute the topologically
// ordered SuperRegs list.
for (unsigned i = 0, e = Registers.size(); i != e; ++i)
Registers[i]->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())
throw std::string("No 'RegisterClass' subclasses defined!");
// Allocate user-defined register classes.
RegClasses.reserve(RCs.size());
for (unsigned i = 0, e = RCs.size(); i != e; ++i)
addToMaps(new CodeGenRegisterClass(*this, RCs[i]));
// Infer missing classes to create a full algebra.
computeInferredRegisterClasses();
// Order register classes topologically and assign enum values.
array_pod_sort(RegClasses.begin(), RegClasses.end(), TopoOrderRC);
for (unsigned i = 0, e = RegClasses.size(); i != e; ++i)
RegClasses[i]->EnumValue = i;
CodeGenRegisterClass::computeSubClasses(*this);
}
// Create a synthetic CodeGenSubRegIndex without a corresponding Record.
CodeGenSubRegIndex*
CodeGenRegBank::createSubRegIndex(StringRef Name, StringRef Namespace) {
CodeGenSubRegIndex *Idx = new CodeGenSubRegIndex(Name, Namespace,
SubRegIndices.size() + 1);
SubRegIndices.push_back(Idx);
return Idx;
}
CodeGenSubRegIndex *CodeGenRegBank::getSubRegIdx(Record *Def) {
CodeGenSubRegIndex *&Idx = Def2SubRegIdx[Def];
if (Idx)
return Idx;
Idx = new CodeGenSubRegIndex(Def, SubRegIndices.size() + 1);
SubRegIndices.push_back(Idx);
return Idx;
}
CodeGenRegister *CodeGenRegBank::getReg(Record *Def) {
CodeGenRegister *&Reg = Def2Reg[Def];
if (Reg)
return Reg;
Reg = new CodeGenRegister(Def, Registers.size() + 1);
Registers.push_back(Reg);
return Reg;
}
void CodeGenRegBank::addToMaps(CodeGenRegisterClass *RC) {
RegClasses.push_back(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::Set *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.
CodeGenRegisterClass *NewRC = new CodeGenRegisterClass(*this, Name, K);
addToMaps(NewRC);
return NewRC;
}
CodeGenRegisterClass *CodeGenRegBank::getRegClass(Record *Def) {
if (CodeGenRegisterClass *RC = Def2RC[Def])
return RC;
throw TGError(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();
for (unsigned i = 1, e = Parts.size(); i != e; ++i) {
Name += '_';
Name += Parts[i]->getName();
}
return Idx = createSubRegIndex(Name, Parts.front()->getNamespace());
}
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 (unsigned i = 0, e = Registers.size(); i != e; ++i) {
CodeGenRegister *Reg1 = Registers[i];
// 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());
}
}
}
// We don't care about the difference between (Idx1, Idx2) -> Idx2 and invalid
// compositions, so remove any mappings of that form.
for (unsigned i = 0, e = SubRegIndices.size(); i != e; ++i)
SubRegIndices[i]->cleanComposites();
}
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::Set 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 std::vector<CodeGenRegister*> &Registers = RegBank.getRegisters();
// The Register EnumValue is one greater than its index into Registers.
assert(Registers.size() == Registers[Registers.size()-1]->EnumValue &&
"register enum value mismatch");
// For simplicitly make the SetID the same as EnumValue.
IntEqClasses UberSetIDs(Registers.size()+1);
std::set<unsigned> AllocatableRegs;
for (unsigned i = 0, e = RegBank.getRegClasses().size(); i != e; ++i) {
CodeGenRegisterClass *RegClass = RegBank.getRegClasses()[i];
if (!RegClass->Allocatable)
continue;
const CodeGenRegister::Set &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 (CodeGenRegister::Set::const_iterator I = llvm::next(Regs.begin()),
E = Regs.end(); I != E; ++I) {
AllocatableRegs.insert((*I)->EnumValue);
UberSetIDs.join(USetID, (*I)->EnumValue);
}
}
// Combine non-allocatable regs.
for (unsigned i = 0, e = Registers.size(); i != e; ++i) {
unsigned RegNum = Registers[i]->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());
for (unsigned i = 0, e = Registers.size(); i != e; ++i) {
const CodeGenRegister *Reg = Registers[i];
unsigned USetID = UberSetIDs[Reg->EnumValue];
if (!USetID)
USetID = ZeroID;
else if (USetID == ZeroID)
USetID = 0;
UberRegSet *USet = &UberSets[USetID];
USet->Regs.insert(Reg);
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 = llvm::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 = 0;
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;
// Update the set weight.
I->Weight = MaxWeight;
// Find singular determinants.
for (CodeGenRegister::Set::iterator RegI = I->Regs.begin(),
RegE = I->Regs.end(); RegI != RegE; ++RegI) {
if ((*RegI)->getRegUnits().size() == 1
&& (*RegI)->getWeight(RegBank) == I->Weight)
mergeRegUnits(I->SingularDeterminants, (*RegI)->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,
std::set<unsigned> &NormalRegs,
CodeGenRegister::RegUnitList &NormalUnits,
CodeGenRegBank &RegBank) {
bool Changed = false;
if (!NormalRegs.insert(Reg->EnumValue).second)
return Changed;
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().front();
if (Reg->getRegUnits().size() != 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.
mergeRegUnits(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 (unsigned i = 0, e = Registers.size(); i != e; ++i) {
CodeGenRegister::RegUnitList NormalUnits;
std::set<unsigned> NormalRegs;
Changed |= normalizeWeight(Registers[i], 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.
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;
const RegUnitSet &SuperSet = RegUnitSets[SuperIdx];
if (isRegUnitSubSet(SubSet.Units, SuperSet.Units)
&& (SubSet.Units.size() + 3 > SuperSet.Units.size())) {
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() {
// Compute a unique RegUnitSet for each RegClass.
const ArrayRef<CodeGenRegisterClass*> &RegClasses = getRegClasses();
unsigned NumRegClasses = RegClasses.size();
for (unsigned RCIdx = 0, RCEnd = NumRegClasses; RCIdx != RCEnd; ++RCIdx) {
if (!RegClasses[RCIdx]->Allocatable)
continue;
// Speculatively grow the RegUnitSets to hold the new set.
RegUnitSets.resize(RegUnitSets.size() + 1);
RegUnitSets.back().Name = RegClasses[RCIdx]->getName();
// Compute a sorted list of units in this class.
RegClasses[RCIdx]->buildRegUnitSet(RegUnitSets.back().Units);
// Find an existing RegUnitSet.
std::vector<RegUnitSet>::const_iterator SetI =
findRegUnitSet(RegUnitSets, RegUnitSets.back());
if (SetI != llvm::prior(RegUnitSets.end()))
RegUnitSets.pop_back();
}
// Iteratively prune unit sets.
pruneUnitSets();
// 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 != llvm::prior(RegUnitSets.end()))
RegUnitSets.pop_back();
}
}
// Iteratively prune unit sets after inferring supersets.
pruneUnitSets();
// For each register class, list the UnitSets that are supersets.
RegClassUnitSets.resize(NumRegClasses);
for (unsigned RCIdx = 0, RCEnd = NumRegClasses; RCIdx != RCEnd; ++RCIdx) {
if (!RegClasses[RCIdx]->Allocatable)
continue;
// Recompute the sorted list of units in this class.
std::vector<unsigned> RegUnits;
RegClasses[RCIdx]->buildRegUnitSet(RegUnits);
// Don't increase pressure for unallocatable regclasses.
if (RegUnits.empty())
continue;
// Find all supersets.
for (unsigned USIdx = 0, USEnd = RegUnitSets.size();
USIdx != USEnd; ++USIdx) {
if (isRegUnitSubSet(RegUnits, RegUnitSets[USIdx].Units))
RegClassUnitSets[RCIdx].push_back(USIdx);
}
assert(!RegClassUnitSets[RCIdx].empty() && "missing unit set for regclass");
}
}
void CodeGenRegBank::computeDerivedInfo() {
computeComposites();
// 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();
}
//
// 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) {
for (unsigned rci = 0, rce = RegClasses.size(); rci != rce; ++rci) {
CodeGenRegisterClass *RC1 = RC;
CodeGenRegisterClass *RC2 = RegClasses[rci];
if (RC1 == RC2)
continue;
// Compute the set intersection of RC1 and RC2.
const CodeGenRegister::Set &Memb1 = RC1->getMembers();
const CodeGenRegister::Set &Memb2 = RC2->getMembers();
CodeGenRegister::Set Intersection;
std::set_intersection(Memb1.begin(), Memb1.end(),
Memb2.begin(), Memb2.end(),
std::inserter(Intersection, Intersection.begin()),
CodeGenRegister::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<CodeGenSubRegIndex*, CodeGenRegister::Set,
CodeGenSubRegIndex::Less> SubReg2SetMap;
// Compute the set of registers supporting each SubRegIndex.
SubReg2SetMap SRSets;
for (CodeGenRegister::Set::const_iterator RI = RC->getMembers().begin(),
RE = RC->getMembers().end(); RI != RE; ++RI) {
const CodeGenRegister::SubRegMap &SRM = (*RI)->getSubRegs();
for (CodeGenRegister::SubRegMap::const_iterator I = SRM.begin(),
E = SRM.end(); I != E; ++I)
SRSets[I->first].insert(*RI);
}
// Find matching classes for all SRSets entries. Iterate in SubRegIndex
// numerical order to visit synthetic indices last.
for (unsigned sri = 0, sre = SubRegIndices.size(); sri != sre; ++sri) {
CodeGenSubRegIndex *SubIdx = SubRegIndices[sri];
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,
unsigned FirstSubRegRC) {
SmallVector<std::pair<const CodeGenRegister*,
const CodeGenRegister*>, 16> SSPairs;
BitVector TopoSigs(getNumTopoSigs());
// Iterate in SubRegIndex numerical order to visit synthetic indices last.
for (unsigned sri = 0, sre = SubRegIndices.size(); sri != sre; ++sri) {
CodeGenSubRegIndex *SubIdx = SubRegIndices[sri];
// 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 (CodeGenRegister::Set::const_iterator RI = RC->getMembers().begin(),
RE = RC->getMembers().end(); RI != RE; ++RI) {
const CodeGenRegister *Super = *RI;
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.
for (unsigned rci = FirstSubRegRC, rce = RegClasses.size(); rci != rce;
++rci) {
CodeGenRegisterClass *SubRC = RegClasses[rci];
// Topological shortcut: SubRC members have the wrong shape.
if (!TopoSigs.anyCommon(SubRC->getTopoSigs()))
continue;
// Compute the subset of RC that maps into SubRC.
CodeGenRegister::Set SubSet;
for (unsigned i = 0, e = SSPairs.size(); i != e; ++i)
if (SubRC->contains(SSPairs[i].second))
SubSet.insert(SSPairs[i].first);
if (SubSet.empty())
continue;
// RC injects completely into SubRC.
if (SubSet.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, &SubSet, RC->getName() +
"_with_" + SubIdx->getName() +
"_in_" + SubRC->getName());
}
}
}
//
// Infer missing register classes.
//
void CodeGenRegBank::computeInferredRegisterClasses() {
// 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.
unsigned FirstNewRC = RegClasses.size();
// Visit all register classes, including the ones being added by the loop.
for (unsigned rci = 0; rci != RegClasses.size(); ++rci) {
CodeGenRegisterClass *RC = RegClasses[rci];
// 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 (rci + 1 == FirstNewRC) {
unsigned NextNewRC = RegClasses.size();
for (unsigned rci2 = 0; rci2 != FirstNewRC; ++rci2)
inferMatchingSuperRegClass(RegClasses[rci2], FirstNewRC);
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);
ArrayRef<CodeGenRegisterClass*> RCs = getRegClasses();
const CodeGenRegisterClass *FoundRC = 0;
for (unsigned i = 0, e = RCs.size(); i != e; ++i) {
const CodeGenRegisterClass &RC = *RCs[i];
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 0;
// 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 0;
}
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;
}