+// 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);
+}
+