Move the list of registers into CodeGenRegBank.

Also move the sub-register index computations from RegisterInfoEmitter
into CodeGenRegBank.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132865 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 253 insertions, 207 deletions

diff --git a/utils/TableGen/CodeGenRegisters.cpp b/utils/TableGen/CodeGenRegisters.cpp
index 22fc25b61a..a4504e4f5e 100644
--- a/utils/TableGen/CodeGenRegisters.cpp
+++ b/utils/TableGen/CodeGenRegisters.cpp
@@ -14,6 +14,7 @@
 
 #include "CodeGenRegisters.h"
 #include "CodeGenTarget.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
 
 using namespace llvm;
@@ -22,14 +23,111 @@ using namespace llvm;
 //                              CodeGenRegister
 //===----------------------------------------------------------------------===//
 
-CodeGenRegister::CodeGenRegister(Record *R) : TheDef(R) {
-  CostPerUse = R->getValueAsInt("CostPerUse");
-}
+CodeGenRegister::CodeGenRegister(Record *R, unsigned Enum)
+  : TheDef(R),
+    EnumValue(Enum),
+    CostPerUse(R->getValueAsInt("CostPerUse")),
+    SubRegsComplete(false)
+{}
 
 const std::string &CodeGenRegister::getName() const {
   return TheDef->getName();
 }
 
+namespace {
+  struct Orphan {
+    CodeGenRegister *SubReg;
+    Record *First, *Second;
+    Orphan(CodeGenRegister *r, Record *a, Record *b)
+      : SubReg(r), First(a), Second(b) {}
+  };
+}
+
+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);
+    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));
+  }
+
+  // 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;
+}
+
 //===----------------------------------------------------------------------===//
 //                            CodeGenRegisterClass
 //===----------------------------------------------------------------------===//
@@ -104,19 +202,45 @@ const std::string &CodeGenRegisterClass::getName() const {
 //===----------------------------------------------------------------------===//
 
 CodeGenRegBank::CodeGenRegBank(RecordKeeper &Records) : Records(Records) {
-  // Read in the user-defined (named) sub-register indices. More indices will
-  // be synthesized.
+  // Read in the user-defined (named) sub-register indices.
+  // More indices will be synthesized later.
   SubRegIndices = Records.getAllDerivedDefinitions("SubRegIndex");
   std::sort(SubRegIndices.begin(), SubRegIndices.end(), LessRecord());
   NumNamedIndices = SubRegIndices.size();
+
+  // 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)
+    Registers.push_back(CodeGenRegister(Regs[i], i + 1));
 }
 
-Record *CodeGenRegBank::getCompositeSubRegIndex(Record *A, Record *B) {
+CodeGenRegister *CodeGenRegBank::getReg(Record *Def) {
+  if (Def2Reg.empty())
+    for (unsigned i = 0, e = Registers.size(); i != e; ++i)
+      Def2Reg[Registers[i].TheDef] = &Registers[i];
+
+  if (CodeGenRegister *Reg = Def2Reg[Def])
+    return Reg;
+
+  throw TGError(Def->getLoc(), "Not a known Register!");
+}
+
+Record *CodeGenRegBank::getCompositeSubRegIndex(Record *A, Record *B,
+                                                bool create) {
+  // Look for an existing entry.
+  Record *&Comp = Composite[std::make_pair(A, B)];
+  if (Comp || !create)
+    return Comp;
+
+  // None exists, synthesize one.
   std::string Name = A->getName() + "_then_" + B->getName();
-  Record *R = new Record(Name, SMLoc(), Records);
-  Records.addDef(R);
-  SubRegIndices.push_back(R);
-  return R;
+  Comp = new Record(Name, SMLoc(), Records);
+  Records.addDef(Comp);
+  SubRegIndices.push_back(Comp);
+  return Comp;
 }
 
 unsigned CodeGenRegBank::getSubRegIndexNo(Record *idx) {
@@ -126,3 +250,63 @@ unsigned CodeGenRegBank::getSubRegIndexNo(Record *idx) {
   return (i - SubRegIndices.begin()) + 1;
 }
 
+void CodeGenRegBank::computeComposites() {
+  // 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].getSubRegs(*this);
+
+  for (unsigned i = 0, e = Registers.size(); i != e; ++i) {
+    CodeGenRegister *Reg1 = &Registers[i];
+    const CodeGenRegister::SubRegMap &SRM1 = Reg1->getSubRegs(*this);
+    for (CodeGenRegister::SubRegMap::const_iterator i1 = SRM1.begin(),
+         e1 = SRM1.end(); i1 != e1; ++i1) {
+      Record *Idx1 = i1->first;
+      CodeGenRegister *Reg2 = i1->second;
+      // Ignore identity compositions.
+      if (Reg1 == Reg2)
+        continue;
+      const CodeGenRegister::SubRegMap &SRM2 = Reg2->getSubRegs(*this);
+      // Try composing Idx1 with another SubRegIndex.
+      for (CodeGenRegister::SubRegMap::const_iterator i2 = SRM2.begin(),
+           e2 = SRM2.end(); i2 != e2; ++i2) {
+        std::pair<Record*, Record*> IdxPair(Idx1, i2->first);
+        CodeGenRegister *Reg3 = i2->second;
+        // Ignore identity compositions.
+        if (Reg2 == Reg3)
+          continue;
+        // OK Reg1:IdxPair == Reg3. Find the index with Reg:Idx == Reg3.
+        for (CodeGenRegister::SubRegMap::const_iterator i1d = SRM1.begin(),
+             e1d = SRM1.end(); i1d != e1d; ++i1d) {
+          if (i1d->second == Reg3) {
+            std::pair<CompositeMap::iterator, bool> Ins =
+              Composite.insert(std::make_pair(IdxPair, i1d->first));
+            // Conflicting composition? Emit a warning but allow it.
+            if (!Ins.second && Ins.first->second != i1d->first) {
+              errs() << "Warning: SubRegIndex " << getQualifiedName(Idx1)
+                     << " and " << getQualifiedName(IdxPair.second)
+                     << " compose ambiguously as "
+                     << getQualifiedName(Ins.first->second) << " or "
+                     << getQualifiedName(i1d->first) << "\n";
+            }
+          }
+        }
+      }
+    }
+  }
+
+  // We don't care about the difference between (Idx1, Idx2) -> Idx2 and invalid
+  // compositions, so remove any mappings of that form.
+  for (CompositeMap::iterator i = Composite.begin(), e = Composite.end();
+       i != e;) {
+    CompositeMap::iterator j = i;
+    ++i;
+    if (j->first.second == j->second)
+      Composite.erase(j);
+  }
+}
+
+void CodeGenRegBank::computeDerivedInfo() {
+  computeComposites();
+}
+
diff --git a/utils/TableGen/CodeGenRegisters.h b/utils/TableGen/CodeGenRegisters.h
index 0dba925afe..09341f00d0 100644
--- a/utils/TableGen/CodeGenRegisters.h
+++ b/utils/TableGen/CodeGenRegisters.h
@@ -15,24 +15,43 @@
 #ifndef CODEGEN_REGISTERS_H
 #define CODEGEN_REGISTERS_H
 
+#include "Record.h"
 #include "llvm/CodeGen/ValueTypes.h"
 #include "llvm/ADT/DenseMap.h"
+#include <cstdlib>
+#include <map>
 #include <string>
-#include <vector>
 #include <set>
-#include <cstdlib>
+#include <vector>
 
 namespace llvm {
-  class Record;
-  class RecordKeeper;
+  class CodeGenRegBank;
 
   /// CodeGenRegister - Represents a register definition.
   struct CodeGenRegister {
     Record *TheDef;
-    const std::string &getName() const;
     unsigned EnumValue;
     unsigned CostPerUse;
-    CodeGenRegister(Record *R);
+
+    // Map SubRegIndex -> Register.
+    typedef std::map<Record*, CodeGenRegister*, LessRecord> SubRegMap;
+
+    CodeGenRegister(Record *R, unsigned Enum);
+
+    const std::string &getName() const;
+
+    // Get a map of sub-registers computed lazily.
+    // This includes unique entries for all sub-sub-registers.
+    const SubRegMap &getSubRegs(CodeGenRegBank&);
+
+    const SubRegMap &getSubRegs() const {
+      assert(SubRegsComplete && "Must precompute sub-registers");
+      return SubRegs;
+    }
+
+  private:
+    bool SubRegsComplete;
+    SubRegMap SubRegs;
   };
 
 
@@ -104,26 +123,41 @@ namespace llvm {
   // them.
   class CodeGenRegBank {
     RecordKeeper &Records;
-
-    // Sub-register indices. The first NumNamedIndices are defined by the user
-    // in the .td files. The rest are synthesized such that all sub-registers
-    // have a unique name.
     std::vector<Record*> SubRegIndices;
-
     unsigned NumNamedIndices;
+    std::vector<CodeGenRegister> Registers;
+    DenseMap<Record*, CodeGenRegister*> Def2Reg;
+
+    // Composite SubRegIndex instances.
+    // Map (SubRegIndex, SubRegIndex) -> SubRegIndex.
+    typedef DenseMap<std::pair<Record*, Record*>, Record*> CompositeMap;
+    CompositeMap Composite;
+
+    // Populate the Composite map from sub-register relationships.
+    void computeComposites();
 
   public:
     CodeGenRegBank(RecordKeeper&);
 
+    // Sub-register indices. The first NumNamedIndices are defined by the user
+    // in the .td files. The rest are synthesized such that all sub-registers
+    // have a unique name.
     const std::vector<Record*> &getSubRegIndices() { return SubRegIndices; }
-
     unsigned getNumNamedIndices() { return NumNamedIndices; }
 
     // Map a SubRegIndex Record to its enum value.
     unsigned getSubRegIndexNo(Record *idx);
 
-    // Create a new sub-register index representing the A+B composition.
-    Record *getCompositeSubRegIndex(Record *A, Record *B);
+    // Find or create a sub-register index representing the A+B composition.
+    Record *getCompositeSubRegIndex(Record *A, Record *B, bool create = false);
+
+    const std::vector<CodeGenRegister> &getRegisters() { return Registers; }
+
+    // Find a register from its Record def.
+    CodeGenRegister *getReg(Record*);
+
+    // Computed derived records such as missing sub-register indices.
+    void computeDerivedInfo();
   };
 }
 
diff --git a/utils/TableGen/CodeGenTarget.cpp b/utils/TableGen/CodeGenTarget.cpp
index e337b56406..a0c64ffa8c 100644
--- a/utils/TableGen/CodeGenTarget.cpp
+++ b/utils/TableGen/CodeGenTarget.cpp
@@ -163,19 +163,6 @@ CodeGenRegBank &CodeGenTarget::getRegBank() const {
   return *RegBank;
 }
 
-void CodeGenTarget::ReadRegisters() const {
-  std::vector<Record*> Regs = Records.getAllDerivedDefinitions("Register");
-  if (Regs.empty())
-    throw std::string("No 'Register' subclasses defined!");
-  std::sort(Regs.begin(), Regs.end(), LessRecord());
-
-  Registers.reserve(Regs.size());
-  Registers.assign(Regs.begin(), Regs.end());
-  // Assign the enumeration values.
-  for (unsigned i = 0, e = Registers.size(); i != e; ++i)
-    Registers[i].EnumValue = i + 1;
-}
-
 void CodeGenTarget::ReadRegisterClasses() const {
   std::vector<Record*> RegClasses =
     Records.getAllDerivedDefinitions("RegisterClass");
@@ -189,7 +176,7 @@ void CodeGenTarget::ReadRegisterClasses() const {
 /// getRegisterByName - If there is a register with the specific AsmName,
 /// return it.
 const CodeGenRegister *CodeGenTarget::getRegisterByName(StringRef Name) const {
-  const std::vector<CodeGenRegister> &Regs = getRegisters();
+  const std::vector<CodeGenRegister> &Regs = getRegBank().getRegisters();
   for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
     const CodeGenRegister &Reg = Regs[i];
     if (Reg.TheDef->getValueAsString("AsmName") == Name)
diff --git a/utils/TableGen/CodeGenTarget.h b/utils/TableGen/CodeGenTarget.h
index 86050fb7fa..1f1c34cb98 100644
--- a/utils/TableGen/CodeGenTarget.h
+++ b/utils/TableGen/CodeGenTarget.h
@@ -66,10 +66,8 @@ class CodeGenTarget {
 
   mutable DenseMap<const Record*, CodeGenInstruction*> Instructions;
   mutable CodeGenRegBank *RegBank;
-  mutable std::vector<CodeGenRegister> Registers;
   mutable std::vector<CodeGenRegisterClass> RegisterClasses;
   mutable std::vector<MVT::SimpleValueType> LegalValueTypes;
-  void ReadRegisters() const;
   void ReadRegisterClasses() const;
   void ReadInstructions() const;
   void ReadLegalValueTypes() const;
@@ -101,8 +99,7 @@ public:
   CodeGenRegBank &getRegBank() const;
 
   const std::vector<CodeGenRegister> &getRegisters() const {
-    if (Registers.empty()) ReadRegisters();
-    return Registers;
+    return getRegBank().getRegisters();
   }
 
   /// getRegisterByName - If there is a register with the specific AsmName,
diff --git a/utils/TableGen/RegisterInfoEmitter.cpp b/utils/TableGen/RegisterInfoEmitter.cpp
index 27835b7b23..5a441e285e 100644
--- a/utils/TableGen/RegisterInfoEmitter.cpp
+++ b/utils/TableGen/RegisterInfoEmitter.cpp
@@ -168,159 +168,6 @@ static void addSubSuperReg(Record *R, Record *S,
       addSubSuperReg(R, *I, SubRegs, SuperRegs, Aliases);
 }
 
-struct RegisterMaps {
-  // Map SubRegIndex -> Register
-  typedef std::map<Record*, Record*, LessRecord> SubRegMap;
-  // Map Register -> SubRegMap
-  typedef std::map<Record*, SubRegMap> SubRegMaps;
-
-  SubRegMaps SubReg;
-  SubRegMap &inferSubRegIndices(Record *Reg, CodeGenTarget &);
-
-  // Composite SubRegIndex instances.
-  // Map (SubRegIndex,SubRegIndex) -> SubRegIndex
-  typedef DenseMap<std::pair<Record*,Record*>,Record*> CompositeMap;
-  CompositeMap Composite;
-
-  // Compute SubRegIndex compositions after inferSubRegIndices has run on all
-  // registers.
-  void computeComposites();
-};
-
-// Calculate all subregindices for Reg. Loopy subregs cause infinite recursion.
-RegisterMaps::SubRegMap &RegisterMaps::inferSubRegIndices(Record *Reg,
-                                                        CodeGenTarget &Target) {
-  SubRegMap &SRM = SubReg[Reg];
-  if (!SRM.empty())
-    return SRM;
-  std::vector<Record*> SubRegs = Reg->getValueAsListOfDefs("SubRegs");
-  std::vector<Record*> Indices = Reg->getValueAsListOfDefs("SubRegIndices");
-  if (SubRegs.size() != Indices.size())
-    throw "Register " + Reg->getName() + " SubRegIndices doesn't match SubRegs";
-
-  // First insert the direct subregs and make sure they are fully indexed.
-  for (unsigned i = 0, e = SubRegs.size(); i != e; ++i) {
-    if (!SRM.insert(std::make_pair(Indices[i], SubRegs[i])).second)
-      throw "SubRegIndex " + Indices[i]->getName()
-        + " appears twice in Register " + Reg->getName();
-    inferSubRegIndices(SubRegs[i], Target);
-  }
-
-  // Keep track of inherited subregs and how they can be reached.
-  // Register -> (SubRegIndex, SubRegIndex)
-  typedef std::map<Record*, std::pair<Record*,Record*>, LessRecord> OrphanMap;
-  OrphanMap Orphans;
-
-  // Clone inherited subregs. Here the order is important - earlier subregs take
-  // precedence.
-  for (unsigned i = 0, e = SubRegs.size(); i != e; ++i) {
-    SubRegMap &M = SubReg[SubRegs[i]];
-    for (SubRegMap::iterator si = M.begin(), se = M.end(); si != se; ++si)
-      if (!SRM.insert(*si).second)
-        Orphans[si->second] = std::make_pair(Indices[i], si->first);
-  }
-
-  // Finally process the composites.
-  ListInit *Comps = Reg->getValueAsListInit("CompositeIndices");
-  for (unsigned i = 0, e = Comps->size(); i != e; ++i) {
-    DagInit *Pat = dynamic_cast<DagInit*>(Comps->getElement(i));
-    if (!Pat)
-      throw "Invalid dag '" + Comps->getElement(i)->getAsString()
-        + "' in CompositeIndices";
-    DefInit *BaseIdxInit = dynamic_cast<DefInit*>(Pat->getOperator());
-    if (!BaseIdxInit || !BaseIdxInit->getDef()->isSubClassOf("SubRegIndex"))
-      throw "Invalid SubClassIndex in " + Pat->getAsString();
-
-    // Resolve list of subreg indices into R2.
-    Record *R2 = Reg;
-    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 "Invalid SubClassIndex in " + Pat->getAsString();
-      SubRegMap::const_iterator ni = SubReg[R2].find(IdxInit->getDef());
-      if (ni == SubReg[R2].end())
-        throw "Composite " + Pat->getAsString() + " refers to bad index in "
-          + R2->getName();
-      R2 = ni->second;
-    }
-
-    // Insert composite index. Allow overriding inherited indices etc.
-    SRM[BaseIdxInit->getDef()] = R2;
-
-    // R2 is now directly addressable, no longer an orphan.
-    Orphans.erase(R2);
-  }
-
-  // Now Orphans contains the inherited subregisters without a direct index.
-  // Create inferred indexes for all missing entries.
-  for (OrphanMap::iterator I = Orphans.begin(), E = Orphans.end(); I != E;
-       ++I) {
-    Record *&Comp = Composite[I->second];
-    if (!Comp)
-      Comp = Target.getRegBank().getCompositeSubRegIndex(I->second.first,
-                                                         I->second.second);
-    SRM[Comp] = I->first;
-  }
-
-  return SRM;
-}
-
-void RegisterMaps::computeComposites() {
-  for (SubRegMaps::const_iterator sri = SubReg.begin(), sre = SubReg.end();
-       sri != sre; ++sri) {
-    Record *Reg1 = sri->first;
-    const SubRegMap &SRM1 = sri->second;
-    for (SubRegMap::const_iterator i1 = SRM1.begin(), e1 = SRM1.end();
-         i1 != e1; ++i1) {
-      Record *Idx1 = i1->first;
-      Record *Reg2 = i1->second;
-      // Ignore identity compositions.
-      if (Reg1 == Reg2)
-        continue;
-      // If Reg2 has no subregs, Idx1 doesn't compose.
-      if (!SubReg.count(Reg2))
-        continue;
-      const SubRegMap &SRM2 = SubReg[Reg2];
-      // Try composing Idx1 with another SubRegIndex.
-      for (SubRegMap::const_iterator i2 = SRM2.begin(), e2 = SRM2.end();
-           i2 != e2; ++i2) {
-        std::pair<Record*,Record*> IdxPair(Idx1, i2->first);
-        Record *Reg3 = i2->second;
-        // OK Reg1:IdxPair == Reg3. Find the index with Reg:Idx == Reg3.
-        for (SubRegMap::const_iterator i1d = SRM1.begin(), e1d = SRM1.end();
-             i1d != e1d; ++i1d) {
-          // Ignore identity compositions.
-          if (Reg2 == Reg3)
-            continue;
-          if (i1d->second == Reg3) {
-            std::pair<CompositeMap::iterator,bool> Ins =
-              Composite.insert(std::make_pair(IdxPair, i1d->first));
-            // Conflicting composition? Emit a warning but allow it.
-            if (!Ins.second && Ins.first->second != i1d->first) {
-              errs() << "Warning: SubRegIndex " << getQualifiedName(Idx1)
-                     << " and " << getQualifiedName(IdxPair.second)
-                     << " compose ambiguously as "
-                     << getQualifiedName(Ins.first->second) << " or "
-                     << getQualifiedName(i1d->first) << "\n";
-            }
-          }
-        }
-      }
-    }
-  }
-
-  // We don't care about the difference between (Idx1, Idx2) -> Idx2 and invalid
-  // compositions, so remove any mappings of that form.
-  for (CompositeMap::iterator i = Composite.begin(), e = Composite.end();
-       i != e;) {
-    CompositeMap::iterator j = i;
-    ++i;
-    if (j->first.second == j->second)
-      Composite.erase(j);
-  }
-}
-
 class RegisterSorter {
 private:
   std::map<Record*, std::set<Record*>, LessRecord> &RegisterSubRegs;
@@ -340,6 +187,7 @@ public:
 void RegisterInfoEmitter::run(raw_ostream &OS) {
   CodeGenTarget Target(Records);
   CodeGenRegBank &RegBank = Target.getRegBank();
+  RegBank.computeDerivedInfo();
   EmitSourceFileHeader("Register Information Source Fragment", OS);
 
   OS << "namespace llvm {\n\n";
@@ -866,9 +714,6 @@ void RegisterInfoEmitter::run(raw_ostream &OS) {
   // Calculate the mapping of subregister+index pairs to physical registers.
   // This will also create further anonymous indexes.
   unsigned NamedIndices = RegBank.getNumNamedIndices();
-  RegisterMaps RegMaps;
-  for (unsigned i = 0, e = Regs.size(); i != e; ++i)
-    RegMaps.inferSubRegIndices(Regs[i].TheDef, Target);
 
   // Emit SubRegIndex names, skipping 0
   const std::vector<Record*> &SubRegIndices = RegBank.getSubRegIndices();
@@ -901,16 +746,16 @@ void RegisterInfoEmitter::run(raw_ostream &OS) {
      << "  switch (RegNo) {\n"
      << "  default:\n    return 0;\n";
   for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
-    RegisterMaps::SubRegMap &SRM = RegMaps.SubReg[Regs[i].TheDef];
+    const CodeGenRegister::SubRegMap &SRM = Regs[i].getSubRegs();
     if (SRM.empty())
       continue;
     OS << "  case " << getQualifiedName(Regs[i].TheDef) << ":\n";
     OS << "    switch (Index) {\n";
     OS << "    default: return 0;\n";
-    for (RegisterMaps::SubRegMap::const_iterator ii = SRM.begin(),
+    for (CodeGenRegister::SubRegMap::const_iterator ii = SRM.begin(),
          ie = SRM.end(); ii != ie; ++ii)
       OS << "    case " << getQualifiedName(ii->first)
-         << ": return " << getQualifiedName(ii->second) << ";\n";
+         << ": return " << getQualifiedName(ii->second->TheDef) << ";\n";
     OS << "    };\n" << "    break;\n";
   }
   OS << "  };\n";
@@ -922,13 +767,13 @@ void RegisterInfoEmitter::run(raw_ostream &OS) {
      << "  switch (RegNo) {\n"
      << "  default:\n    return 0;\n";
    for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
-     RegisterMaps::SubRegMap &SRM = RegMaps.SubReg[Regs[i].TheDef];
+     const CodeGenRegister::SubRegMap &SRM = Regs[i].getSubRegs();
      if (SRM.empty())
        continue;
     OS << "  case " << getQualifiedName(Regs[i].TheDef) << ":\n";
-    for (RegisterMaps::SubRegMap::const_iterator ii = SRM.begin(),
+    for (CodeGenRegister::SubRegMap::const_iterator ii = SRM.begin(),
          ie = SRM.end(); ii != ie; ++ii)
-      OS << "    if (SubRegNo == " << getQualifiedName(ii->second)
+      OS << "    if (SubRegNo == " << getQualifiedName(ii->second->TheDef)
          << ")  return " << getQualifiedName(ii->first) << ";\n";
     OS << "    return 0;\n";
   }
@@ -937,7 +782,6 @@ void RegisterInfoEmitter::run(raw_ostream &OS) {
   OS << "}\n\n";
 
   // Emit composeSubRegIndices
-  RegMaps.computeComposites();
   OS << "unsigned " << ClassName
      << "::composeSubRegIndices(unsigned IdxA, unsigned IdxB) const {\n"
      << "  switch (IdxA) {\n"
@@ -945,8 +789,8 @@ void RegisterInfoEmitter::run(raw_ostream &OS) {
   for (unsigned i = 0, e = SubRegIndices.size(); i != e; ++i) {
     bool Open = false;
     for (unsigned j = 0; j != e; ++j) {
-      if (Record *Comp = RegMaps.Composite.lookup(
-                          std::make_pair(SubRegIndices[i], SubRegIndices[j]))) {
+      if (Record *Comp = RegBank.getCompositeSubRegIndex(SubRegIndices[i],
+                                                         SubRegIndices[j])) {
         if (!Open) {
           OS << "  case " << getQualifiedName(SubRegIndices[i])
              << ": switch(IdxB) {\n    default: return IdxB;\n";