// Compute sets of 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 CodeGenRegBank::
computeOverlaps(std::map<const CodeGenRegister*, CodeGenRegister::Set> &Map) {
assert(Map.empty());
// Collect overlaps that don't follow from rule 2.
for (unsigned i = 0, e = Registers.size(); i != e; ++i) {
CodeGenRegister *Reg = Registers[i];
CodeGenRegister::Set &Overlaps = Map[Reg];
// Reg overlaps itself.
Overlaps.insert(Reg);
// All super-registers overlap.
const CodeGenRegister::SuperRegList &Supers = Reg->getSuperRegs();
Overlaps.insert(Supers.begin(), Supers.end());
// Form symmetrical relations from the special Aliases[] lists.
std::vector<Record*> RegList = Reg->TheDef->getValueAsListOfDefs("Aliases");
for (unsigned i2 = 0, e2 = RegList.size(); i2 != e2; ++i2) {
CodeGenRegister *Reg2 = getReg(RegList[i2]);
CodeGenRegister::Set &Overlaps2 = Map[Reg2];
const CodeGenRegister::SuperRegList &Supers2 = Reg2->getSuperRegs();
// Reg overlaps Reg2 which implies it overlaps supers(Reg2).
Overlaps.insert(Reg2);
Overlaps.insert(Supers2.begin(), Supers2.end());
Overlaps2.insert(Reg);
Overlaps2.insert(Supers.begin(), Supers.end());
}
}
// Apply rule 2. and inherit all sub-register overlaps.
for (unsigned i = 0, e = Registers.size(); i != e; ++i) {
CodeGenRegister *Reg = Registers[i];
CodeGenRegister::Set &Overlaps = Map[Reg];
const CodeGenRegister::SubRegMap &SRM = Reg->getSubRegs();
for (CodeGenRegister::SubRegMap::const_iterator i2 = SRM.begin(),
e2 = SRM.end(); i2 != e2; ++i2) {
CodeGenRegister::Set &Overlaps2 = Map[i2->second];
Overlaps.insert(Overlaps2.begin(), Overlaps2.end());
}
}
}
const CodeGenRegister::SubRegMap &
CodeGenRegister::getSubRegs(CodeGenRegBank &RegBank) {
// Only compute this map once.
if (SubRegsComplete)
return SubRegs;
SubRegsComplete = true;
std::vector<Record*> SubList = TheDef->getValueAsListOfDefs("SubRegs");
std::vector<Record*> Indices = TheDef->getValueAsListOfDefs("SubRegIndices");
if (SubList.size() != Indices.size())
throw TGError(TheDef->getLoc(), "Register " + getName() +
" SubRegIndices doesn't match SubRegs");
// First insert the direct subregs and make sure they are fully indexed.
for (unsigned i = 0, e = SubList.size(); i != e; ++i) {
CodeGenRegister *SR = RegBank.getReg(SubList[i]);
if (!SubRegs.insert(std::make_pair(Indices[i], SR)).second)
throw TGError(TheDef->getLoc(), "SubRegIndex " + Indices[i]->getName() +
" appears twice in Register " + getName());
}
// Keep track of inherited subregs and how they can be reached.
SmallVector<Orphan, 8> Orphans;
// Clone inherited subregs and place duplicate entries on Orphans.
// Here the order is important - earlier subregs take precedence.
for (unsigned i = 0, e = SubList.size(); i != e; ++i) {
CodeGenRegister *SR = RegBank.getReg(SubList[i]);
const SubRegMap &Map = SR->getSubRegs(RegBank);
// Add this as a super-register of SR now all sub-registers are in the list.
// This creates a topological ordering, the exact order depends on the
// order getSubRegs is called on all registers.
SR->SuperRegs.push_back(this);
for (SubRegMap::const_iterator SI = Map.begin(), SE = Map.end(); SI != SE;
++SI) {
if (!SubRegs.insert(*SI).second)
Orphans.push_back(Orphan(SI->second, Indices[i], SI->first));
// Noop sub-register indexes are possible, so avoid duplicates.
if (SI->second != SR)
SI->second->SuperRegs.push_back(this);
}
}
// Process the composites.
ListInit *Comps = TheDef->getValueAsListInit("CompositeIndices");
for (unsigned i = 0, e = Comps->size(); i != e; ++i) {
DagInit *Pat = dynamic_cast<DagInit*>(Comps->getElement(i));
if (!Pat)
throw TGError(TheDef->getLoc(), "Invalid dag '" +
Comps->getElement(i)->getAsString() +
"' in CompositeIndices");
DefInit *BaseIdxInit = dynamic_cast<DefInit*>(Pat->getOperator());
if (!BaseIdxInit || !BaseIdxInit->getDef()->isSubClassOf("SubRegIndex"))
throw TGError(TheDef->getLoc(), "Invalid SubClassIndex in " +
Pat->getAsString());
// Resolve list of subreg indices into R2.
CodeGenRegister *R2 = this;
for (DagInit::const_arg_iterator di = Pat->arg_begin(),
de = Pat->arg_end(); di != de; ++di) {
DefInit *IdxInit = dynamic_cast<DefInit*>(*di);
if (!IdxInit || !IdxInit->getDef()->isSubClassOf("SubRegIndex"))
throw TGError(TheDef->getLoc(), "Invalid SubClassIndex in " +
Pat->getAsString());
const SubRegMap &R2Subs = R2->getSubRegs(RegBank);
SubRegMap::const_iterator ni = R2Subs.find(IdxInit->getDef());
if (ni == R2Subs.end())
throw TGError(TheDef->getLoc(), "Composite " + Pat->getAsString() +
" refers to bad index in " + R2->getName());
R2 = ni->second;
}
// Insert composite index. Allow overriding inherited indices etc.
SubRegs[BaseIdxInit->getDef()] = R2;
// R2 is no longer an orphan.
for (unsigned j = 0, je = Orphans.size(); j != je; ++j)
if (Orphans[j].SubReg == R2)
Orphans[j].SubReg = 0;
}
// Now Orphans contains the inherited subregisters without a direct index.
// Create inferred indexes for all missing entries.
for (unsigned i = 0, e = Orphans.size(); i != e; ++i) {
Orphan &O = Orphans[i];
if (!O.SubReg)
continue;
SubRegs[RegBank.getCompositeSubRegIndex(O.First, O.Second, true)] =
O.SubReg;
}
return SubRegs;
}
const CodeGenRegister::SubRegMap &
CodeGenRegister::getSubRegs(CodeGenRegBank &RegBank) {
// Only compute this map once.
if (SubRegsComplete)
return SubRegs;
SubRegsComplete = true;
std::vector<Record*> SubList = TheDef->getValueAsListOfDefs("SubRegs");
std::vector<Record*> IdxList = TheDef->getValueAsListOfDefs("SubRegIndices");
if (SubList.size() != IdxList.size())
throw TGError(TheDef->getLoc(), "Register " + getName() +
" SubRegIndices doesn't match SubRegs");
// First insert the direct subregs and make sure they are fully indexed.
SmallVector<CodeGenSubRegIndex*, 8> Indices;
for (unsigned i = 0, e = SubList.size(); i != e; ++i) {
CodeGenRegister *SR = RegBank.getReg(SubList[i]);
CodeGenSubRegIndex *Idx = RegBank.getSubRegIdx(IdxList[i]);
Indices.push_back(Idx);
if (!SubRegs.insert(std::make_pair(Idx, SR)).second)
throw TGError(TheDef->getLoc(), "SubRegIndex " + Idx->getName() +
" appears twice in Register " + getName());
}
// 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 = SubList.size(); i != e; ++i) {
CodeGenRegister *SR = RegBank.getReg(SubList[i]);
const SubRegMap &Map = SR->getSubRegs(RegBank);
// Add this as a super-register of SR now all sub-registers are in the list.
// This creates a topological ordering, the exact order depends on the
// order getSubRegs is called on all registers.
SR->SuperRegs.push_back(this);
for (SubRegMap::const_iterator SI = Map.begin(), SE = Map.end(); SI != SE;
++SI) {
if (!SubRegs.insert(*SI).second)
Orphans.insert(SI->second);
// Noop sub-register indexes are possible, so avoid duplicates.
if (SI->second != SR)
SI->second->SuperRegs.push_back(this);
}
}
// 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.
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->getSubRegs(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);
}
}
// Process the composites.
ListInit *Comps = TheDef->getValueAsListInit("CompositeIndices");
for (unsigned i = 0, e = Comps->size(); i != e; ++i) {
DagInit *Pat = dynamic_cast<DagInit*>(Comps->getElement(i));
if (!Pat)
throw TGError(TheDef->getLoc(), "Invalid dag '" +
Comps->getElement(i)->getAsString() +
"' in CompositeIndices");
DefInit *BaseIdxInit = dynamic_cast<DefInit*>(Pat->getOperator());
if (!BaseIdxInit || !BaseIdxInit->getDef()->isSubClassOf("SubRegIndex"))
throw TGError(TheDef->getLoc(), "Invalid SubClassIndex in " +
Pat->getAsString());
CodeGenSubRegIndex *BaseIdx = RegBank.getSubRegIdx(BaseIdxInit->getDef());
// Resolve list of subreg indices into R2.
CodeGenRegister *R2 = this;
for (DagInit::const_arg_iterator di = Pat->arg_begin(),
de = Pat->arg_end(); di != de; ++di) {
DefInit *IdxInit = dynamic_cast<DefInit*>(*di);
if (!IdxInit || !IdxInit->getDef()->isSubClassOf("SubRegIndex"))
throw TGError(TheDef->getLoc(), "Invalid SubClassIndex in " +
Pat->getAsString());
CodeGenSubRegIndex *Idx = RegBank.getSubRegIdx(IdxInit->getDef());
const SubRegMap &R2Subs = R2->getSubRegs(RegBank);
SubRegMap::const_iterator ni = R2Subs.find(Idx);
if (ni == R2Subs.end())
throw TGError(TheDef->getLoc(), "Composite " + Pat->getAsString() +
" refers to bad index in " + R2->getName());
R2 = ni->second;
}
// Insert composite index. Allow overriding inherited indices etc.
SubRegs[BaseIdx] = R2;
// R2 is no longer an orphan.
Orphans.erase(R2);
}
// 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 neccessarily 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->getSubRegs(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;
}
// Initialize RegUnitList. A register with no subregisters creates its own
// unit. Otherwise, it inherits all its subregister's units. Because
// getSubRegs is called recursively, this processes the register hierarchy in
// postorder.
//
// TODO: We currently assume all register units correspond to a named "leaf"
// register. We should also unify register units for ad-hoc register
// aliases. This can be done by iteratively merging units for aliasing
// registers using a worklist.
assert(RegUnits.empty() && "Should only initialize RegUnits once");
if (SubRegs.empty()) {
RegUnits.push_back(RegBank.newRegUnit());
}
else {
for (SubRegMap::const_iterator I = SubRegs.begin(), E = SubRegs.end();
I != E; ++I) {
// Strangely a register may have itself as a subreg (self-cycle) e.g. XMM.
CodeGenRegister *SR = I->second;
if (SR == this) {
if (RegUnits.empty())
RegUnits.push_back(RegBank.newRegUnit());
continue;
}
// Merge the subregister's units into this register's RegUnits.
mergeRegUnits(RegUnits, SR->RegUnits);
}
}
return SubRegs;
}
