CodeGen: Remove PointerLikeRegClass handling from codegen

All uses have been migrated to RegClassByHwMode. This is now
an implementation detail of InstrInfoEmitter for pseudoinstructions.

Author: arsenm

llvm/include/llvm/MC/MCInstrDesc.h

@@ -49,8 +49,7 @@ enum OperandConstraint {
 /// private, all access should go through the MCOperandInfo accessors.
 /// See the accessors for a description of what these are.
 enum OperandFlags {
-  LookupPtrRegClass = 0,
-  LookupRegClassByHwMode,
+  LookupRegClassByHwMode = 0,
   Predicate,
   OptionalDef,
   BranchTarget
@@ -90,9 +89,6 @@ class MCOperandInfo {
   /// operand is a register. If LookupRegClassByHwMode is set, then this is an
   /// index into a table in TargetInstrInfo or MCInstrInfo which contains the
   /// real register class ID.
-  ///
-  /// If isLookupPtrRegClass is set, then this is an index that is passed to
-  /// TargetRegisterInfo::getPointerRegClass(x) to get a dynamic register class.
   int16_t RegClass;
 
   /// These are flags from the MCOI::OperandFlags enum.
@@ -104,13 +100,6 @@ class MCOperandInfo {
   /// Operand constraints (see OperandConstraint enum).
   uint16_t Constraints;
 
-  /// Set if this operand is a pointer value and it requires a callback
-  /// to look up its register class.
-  // TODO: Deprecated in favor of isLookupRegClassByHwMode
-  bool isLookupPtrRegClass() const {
-    return Flags & (1 << MCOI::LookupPtrRegClass);
-  }
-
   /// Set if this operand is a value that requires the current hwmode to look up
   /// its register class.
   bool isLookupRegClassByHwMode() const {

llvm/include/llvm/Target/Target.td

@@ -918,16 +918,23 @@ def slice;
 def encoder;
 def decoder;
 
-/// PointerLikeRegClass - Values that are designed to have pointer width are
-/// derived from this. TableGen treats the register class as having a symbolic
-/// type that it doesn't know, and resolves the actual regclass to use by using
-/// the TargetRegisterInfo::getPointerRegClass() hook at codegen time.
-///
-/// This is deprecated in favor of RegClassByHwMode.
+/// PointerLikeRegClass - Pseudoinstruction operands that are designed
+/// to have pointer width are derived from this. This should only be
+/// used by StandardPseudoInstruction instructions. No target specific
+/// instruction should use this.
 class PointerLikeRegClass<int Kind> {
   int RegClassKind = Kind;
 }
 
+/// ptr_rc definition - Mark this operand as being a pointer value
+/// whose register class needs to be defined by the target. Targets
+/// should provide instruction definition overrides which substitute
+/// the uses of this with the backend defined RegisterClass or
+/// RegClassByHwMode to use for pointer virtual registers for a
+/// particular opcode (typically by defining a subsitute instruction
+/// with RemapPointerOperands).
+def ptr_rc : PointerLikeRegClass<0>;
+
 /// RegClassByHwMode - Operands that change the register class based
 /// on the subtarget are derived from this. TableGen
 /// treats the register class as having a symbolic kind that it
@@ -941,13 +948,6 @@ class RegClassByHwMode<list<HwMode> Modes,
   list<RegisterClass> Objects = RegClasses;
 }
 
-/// ptr_rc definition - Mark this operand as being a pointer value whose
-/// register class is resolved dynamically via a callback to TargetInstrInfo.
-/// FIXME: We should probably change this to a class which contain a list of
-/// flags. But currently we have but one flag.
-// Deprecated, use RegClassByHwMode instead.
-def ptr_rc : PointerLikeRegClass<0>;
-
 /// unknown definition - Mark this operand as being of unknown type, causing
 /// it to be resolved by inference in the context it is used.
 class unknown_class;

llvm/lib/CodeGen/TargetInstrInfo.cpp

@@ -67,10 +67,6 @@ TargetInstrInfo::getRegClass(const MCInstrDesc &MCID, unsigned OpNum,
   const MCOperandInfo &OpInfo = MCID.operands()[OpNum];
   int16_t RegClass = getOpRegClassID(OpInfo);
 
-  // TODO: Remove isLookupPtrRegClass in favor of isLookupRegClassByHwMode
-  if (OpInfo.isLookupPtrRegClass())
-    return TRI->getPointerRegClass(RegClass);
-
   // Instructions like INSERT_SUBREG do not have fixed register classes.
   if (RegClass < 0)
     return nullptr;

llvm/tools/llvm-exegesis/lib/MCInstrDescView.cpp

@@ -120,7 +120,7 @@ Instruction::create(const MCInstrInfo &InstrInfo,
     Operand.IsDef = (OpIndex < Description->getNumDefs());
     Operand.IsEarlyClobber =
         (Description->getOperandConstraint(OpIndex, MCOI::EARLY_CLOBBER) != -1);
-    // TODO(gchatelet): Handle isLookupPtrRegClass.
+    // TODO(gchatelet): Handle LookupRegClassByHwMode.
     if (OpInfo.RegClass >= 0)
       Operand.Tracker = &RATC.getRegisterClass(OpInfo.RegClass);
     int TiedToIndex = Description->getOperandConstraint(OpIndex, MCOI::TIED_TO);

llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp

@@ -1830,10 +1830,6 @@ bool TreePatternNode::UpdateNodeTypeFromInst(unsigned ResNo,
     return UpdateNodeType(ResNo, getValueTypeByHwMode(R, T.getHwModes()), TP);
   }
 
-  // PointerLikeRegClass has a type that is determined at runtime.
-  if (Operand->isSubClassOf("PointerLikeRegClass"))
-    return UpdateNodeType(ResNo, MVT::iPTR, TP);
-
   // Both RegisterClass and RegisterOperand operands derive their types from a
   // register class def.
   const Record *RC = nullptr;
@@ -2412,12 +2408,6 @@ static TypeSetByHwMode getImplicitType(const Record *R, unsigned ResNo,
     const CodeGenHwModes &CGH = CDP.getTargetInfo().getHwModes();
     return TypeSetByHwMode(getValueTypeByHwMode(T, CGH));
   }
-  if (R->isSubClassOf("PointerLikeRegClass")) {
-    assert(ResNo == 0 && "Regclass can only have one result!");
-    TypeSetByHwMode VTS(MVT::iPTR);
-    TP.getInfer().expandOverloads(VTS);
-    return VTS;
-  }
 
   if (R->getName() == "node" || R->getName() == "srcvalue" ||
       R->getName() == "zero_reg" || R->getName() == "immAllOnesV" ||
@@ -3649,8 +3639,7 @@ void CodeGenDAGPatterns::FindPatternInputsAndOutputs(
 
     if (Val->getDef()->isSubClassOf("RegisterClassLike") ||
         Val->getDef()->isSubClassOf("ValueType") ||
-        Val->getDef()->isSubClassOf("RegisterOperand") ||
-        Val->getDef()->isSubClassOf("PointerLikeRegClass")) {
+        Val->getDef()->isSubClassOf("RegisterOperand")) {
       if (Dest->getName().empty())
         I.error("set destination must have a name!");
       if (!InstResults.insert_or_assign(Dest->getName(), Dest).second)

llvm/utils/TableGen/Common/InstructionEncoding.cpp

@@ -35,9 +35,6 @@ InstructionEncoding::findOperandDecoderMethod(const Record *Record) {
     Decoder = "Decode" + Record->getName().str() + "RegisterClass";
   } else if (Record->isSubClassOf("RegClassByHwMode")) {
     Decoder = "Decode" + Record->getName().str() + "RegClassByHwMode";
-  } else if (Record->isSubClassOf("PointerLikeRegClass")) {
-    Decoder = "DecodePointerLikeRegClass" +
-              utostr(Record->getValueAsInt("RegClassKind"));
   }
 
   return {Decoder, true};

llvm/utils/TableGen/DAGISelMatcherGen.cpp

@@ -240,7 +240,6 @@ void MatcherGen::EmitLeafMatchCode(const TreePatternNode &N) {
   if ( // Handle register references.  Nothing to do here, they always match.
       LeafRec->isSubClassOf("RegisterClassLike") ||
       LeafRec->isSubClassOf("RegisterOperand") ||
-      LeafRec->isSubClassOf("PointerLikeRegClass") ||
       LeafRec->isSubClassOf("SubRegIndex") ||
       // Place holder for SRCVALUE nodes. Nothing to do here.
       LeafRec->getName() == "srcvalue")

llvm/utils/TableGen/InstrInfoEmitter.cpp

@@ -183,12 +183,8 @@ InstrInfoEmitter::GetOperandInfo(const CodeGenInstruction &Inst) {
       // Fill in applicable flags.
       Res += "0";
 
-      if (OpR->isSubClassOf("RegClassByHwMode")) {
+      if (OpR->isSubClassOf("RegClassByHwMode"))
         Res += "|(1<<MCOI::LookupRegClassByHwMode)";
-      } else if (OpR->isSubClassOf("PointerLikeRegClass")) {
-        // Ptr value whose register class is resolved via callback.
-        Res += "|(1<<MCOI::LookupPtrRegClass)";
-      }
 
       // Predicate operands.  Check to see if the original unexpanded operand
       // was of type PredicateOp.