[SelectionDAG] Add a OPC_CheckChild2CondCode to SelectionDAGISel to remove a MoveChild and MoveParent pair.

OPC_CheckCondCode is always used as operand 2 of a setcc. And its always surrounded by a MoveChild2 and a MoveParent. By having a dedicated opcode for this case we can reduce the number of bytes needed for this pattern from 4 bytes to 2.

This saves ~3000 bytes in the X86 table.

llvm-svn: 354763

include/llvm/CodeGen/SelectionDAGISel.h

@@ -143,7 +143,7 @@ public:
     OPC_CheckInteger,
     OPC_CheckChild0Integer, OPC_CheckChild1Integer, OPC_CheckChild2Integer,
     OPC_CheckChild3Integer, OPC_CheckChild4Integer,
-    OPC_CheckCondCode,
+    OPC_CheckCondCode, OPC_CheckChild2CondCode,
     OPC_CheckValueType,
     OPC_CheckComplexPat,
     OPC_CheckAndImm, OPC_CheckOrImm,

lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -2756,6 +2756,14 @@ CheckCondCode(const unsigned char *MatcherTable, unsigned &MatcherIndex,
       (ISD::CondCode)MatcherTable[MatcherIndex++];
 }
 
+LLVM_ATTRIBUTE_ALWAYS_INLINE static inline bool
+CheckChild2CondCode(const unsigned char *MatcherTable, unsigned &MatcherIndex,
+                    SDValue N) {
+  if (2 >= N.getNumOperands())
+    return false;
+  return ::CheckCondCode(MatcherTable, MatcherIndex, N.getOperand(2));
+}
+
 LLVM_ATTRIBUTE_ALWAYS_INLINE static inline bool
 CheckValueType(const unsigned char *MatcherTable, unsigned &MatcherIndex,
                SDValue N, const TargetLowering *TLI, const DataLayout &DL) {
@@ -2871,6 +2879,9 @@ static unsigned IsPredicateKnownToFail(const unsigned char *Table,
   case SelectionDAGISel::OPC_CheckCondCode:
     Result = !::CheckCondCode(Table, Index, N);
     return Index;
+  case SelectionDAGISel::OPC_CheckChild2CondCode:
+    Result = !::CheckChild2CondCode(Table, Index, N);
+    return Index;
   case SelectionDAGISel::OPC_CheckValueType:
     Result = !::CheckValueType(Table, Index, N, SDISel.TLI,
                                SDISel.CurDAG->getDataLayout());
@@ -3359,6 +3370,9 @@ void SelectionDAGISel::SelectCodeCommon(SDNode *NodeToMatch,
     case OPC_CheckCondCode:
       if (!::CheckCondCode(MatcherTable, MatcherIndex, N)) break;
       continue;
+    case OPC_CheckChild2CondCode:
+      if (!::CheckChild2CondCode(MatcherTable, MatcherIndex, N)) break;
+      continue;
     case OPC_CheckValueType:
       if (!::CheckValueType(MatcherTable, MatcherIndex, N, TLI,
                             CurDAG->getDataLayout()))

utils/TableGen/DAGISelMatcher.cpp

@@ -211,6 +211,11 @@ void CheckCondCodeMatcher::printImpl(raw_ostream &OS, unsigned indent) const {
   OS.indent(indent) << "CheckCondCode ISD::" << CondCodeName << '\n';
 }
 
+void CheckChild2CondCodeMatcher::printImpl(raw_ostream &OS,
+                                           unsigned indent) const {
+  OS.indent(indent) << "CheckChild2CondCode ISD::" << CondCodeName << '\n';
+}
+
 void CheckValueTypeMatcher::printImpl(raw_ostream &OS, unsigned indent) const {
   OS.indent(indent) << "CheckValueType MVT::" << TypeName << '\n';
 }

utils/TableGen/DAGISelMatcher.h

@@ -66,6 +66,7 @@ public:
     CheckInteger,         // Fail if wrong val.
     CheckChildInteger,    // Fail if child is wrong val.
     CheckCondCode,        // Fail if not condcode.
+    CheckChild2CondCode,  // Fail if child is wrong condcode.
     CheckValueType,
     CheckComplexPat,
     CheckAndImm,
@@ -121,6 +122,7 @@ public:
     case CheckInteger:
     case CheckChildInteger:
     case CheckCondCode:
+    case CheckChild2CondCode:
     case CheckValueType:
     case CheckAndImm:
     case CheckOrImm:
@@ -625,6 +627,27 @@ private:
   }
 };
 
+/// CheckChild2CondCodeMatcher - This checks to see if child 2 node is a
+/// CondCodeSDNode with the specified condition, if not it fails to match.
+class CheckChild2CondCodeMatcher : public Matcher {
+  StringRef CondCodeName;
+public:
+  CheckChild2CondCodeMatcher(StringRef condcodename)
+    : Matcher(CheckChild2CondCode), CondCodeName(condcodename) {}
+
+  StringRef getCondCodeName() const { return CondCodeName; }
+
+  static bool classof(const Matcher *N) {
+    return N->getKind() == CheckChild2CondCode;
+  }
+
+private:
+  void printImpl(raw_ostream &OS, unsigned indent) const override;
+  bool isEqualImpl(const Matcher *M) const override {
+    return cast<CheckChild2CondCodeMatcher>(M)->CondCodeName == CondCodeName;
+  }
+};
+
 /// CheckValueTypeMatcher - This checks to see if the current node is a
 /// VTSDNode with the specified type, if not it fails to match.
 class CheckValueTypeMatcher : public Matcher {

utils/TableGen/DAGISelMatcherEmitter.cpp

@@ -554,6 +554,11 @@ EmitMatcher(const Matcher *N, unsigned Indent, unsigned CurrentIdx,
        << cast<CheckCondCodeMatcher>(N)->getCondCodeName() << ",\n";
     return 2;
 
+  case Matcher::CheckChild2CondCode:
+    OS << "OPC_CheckChild2CondCode, ISD::"
+       << cast<CheckChild2CondCodeMatcher>(N)->getCondCodeName() << ",\n";
+    return 2;
+
   case Matcher::CheckValueType:
     OS << "OPC_CheckValueType, MVT::"
        << cast<CheckValueTypeMatcher>(N)->getTypeName() << ",\n";
@@ -995,6 +1000,7 @@ static StringRef getOpcodeString(Matcher::KindTy Kind) {
   case Matcher::CheckInteger: return "OPC_CheckInteger"; break;
   case Matcher::CheckChildInteger: return "OPC_CheckChildInteger"; break;
   case Matcher::CheckCondCode: return "OPC_CheckCondCode"; break;
+  case Matcher::CheckChild2CondCode: return "OPC_CheckChild2CondCode"; break;
   case Matcher::CheckValueType: return "OPC_CheckValueType"; break;
   case Matcher::CheckComplexPat: return "OPC_CheckComplexPat"; break;
   case Matcher::CheckAndImm: return "OPC_CheckAndImm"; break;

utils/TableGen/DAGISelMatcherOpt.cpp

@@ -55,9 +55,13 @@ static void ContractNodes(std::unique_ptr<Matcher> &MatcherPtr,
       if (MC->getChildNo() < 4)  // Only have CheckChildSame0...3
         New = new CheckChildSameMatcher(MC->getChildNo(), CS->getMatchNumber());
 
-    if (CheckIntegerMatcher *CS = dyn_cast<CheckIntegerMatcher>(MC->getNext()))
+    if (CheckIntegerMatcher *CI = dyn_cast<CheckIntegerMatcher>(MC->getNext()))
       if (MC->getChildNo() < 5)  // Only have CheckChildInteger0...4
-        New = new CheckChildIntegerMatcher(MC->getChildNo(), CS->getValue());
+        New = new CheckChildIntegerMatcher(MC->getChildNo(), CI->getValue());
+
+    if (auto *CCC = dyn_cast<CheckCondCodeMatcher>(MC->getNext()))
+      if (MC->getChildNo() == 2)  // Only have CheckChild2CondCode
+        New = new CheckChild2CondCodeMatcher(CCC->getCondCodeName());
 
     if (New) {
       // Insert the new node.