Add OPC_CheckChildSame0-3 to the DAG isel matcher. This replaces sequences of MoveChild, CheckSame, MoveParent. Saves 846 bytes from the X86 DAG isel matcher, ~300 from ARM, ~840 from Hexagon.

llvm-svn: 191940

llvm/include/llvm/CodeGen/SelectionDAGISel.h

@@ -113,6 +113,8 @@ public:
     OPC_MoveChild,
     OPC_MoveParent,
     OPC_CheckSame,
+    OPC_CheckChild0Same, OPC_CheckChild1Same,
+    OPC_CheckChild2Same, OPC_CheckChild3Same,
     OPC_CheckPatternPredicate,
     OPC_CheckPredicate,
     OPC_CheckOpcode,

llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -2097,6 +2097,18 @@ CheckSame(const unsigned char *MatcherTable, unsigned &MatcherIndex,
   return N == RecordedNodes[RecNo].first;
 }
 
+/// CheckChildSame - Implements OP_CheckChildXSame.
+LLVM_ATTRIBUTE_ALWAYS_INLINE static bool
+CheckChildSame(const unsigned char *MatcherTable, unsigned &MatcherIndex,
+             SDValue N,
+             const SmallVectorImpl<std::pair<SDValue, SDNode*> > &RecordedNodes,
+             unsigned ChildNo) {
+  if (ChildNo >= N.getNumOperands())
+    return false;  // Match fails if out of range child #.
+  return ::CheckSame(MatcherTable, MatcherIndex, N.getOperand(ChildNo),
+                     RecordedNodes);
+}
+
 /// CheckPatternPredicate - Implements OP_CheckPatternPredicate.
 LLVM_ATTRIBUTE_ALWAYS_INLINE static bool
 CheckPatternPredicate(const unsigned char *MatcherTable, unsigned &MatcherIndex,
@@ -2211,6 +2223,13 @@ static unsigned IsPredicateKnownToFail(const unsigned char *Table,
   case SelectionDAGISel::OPC_CheckSame:
     Result = !::CheckSame(Table, Index, N, RecordedNodes);
     return Index;
+  case SelectionDAGISel::OPC_CheckChild0Same:
+  case SelectionDAGISel::OPC_CheckChild1Same:
+  case SelectionDAGISel::OPC_CheckChild2Same:
+  case SelectionDAGISel::OPC_CheckChild3Same:
+    Result = !::CheckChildSame(Table, Index, N, RecordedNodes,
+                        Table[Index-1] - SelectionDAGISel::OPC_CheckChild0Same);
+    return Index;
   case SelectionDAGISel::OPC_CheckPatternPredicate:
     Result = !::CheckPatternPredicate(Table, Index, SDISel);
     return Index;
@@ -2508,6 +2527,14 @@ SelectCodeCommon(SDNode *NodeToMatch, const unsigned char *MatcherTable,
     case OPC_CheckSame:
       if (!::CheckSame(MatcherTable, MatcherIndex, N, RecordedNodes)) break;
       continue;
+
+    case OPC_CheckChild0Same: case OPC_CheckChild1Same:
+    case OPC_CheckChild2Same: case OPC_CheckChild3Same:
+      if (!::CheckChildSame(MatcherTable, MatcherIndex, N, RecordedNodes,
+                            Opcode-OPC_CheckChild0Same))
+        break;
+      continue;
+
     case OPC_CheckPatternPredicate:
       if (!::CheckPatternPredicate(MatcherTable, MatcherIndex, *this)) break;
       continue;

llvm/utils/TableGen/DAGISelMatcher.cpp

@@ -134,6 +134,10 @@ void CheckSameMatcher::printImpl(raw_ostream &OS, unsigned indent) const {
   OS.indent(indent) << "CheckSame " << MatchNumber << '\n';
 }
 
+void CheckChildSameMatcher::printImpl(raw_ostream &OS, unsigned indent) const {
+  OS.indent(indent) << "CheckChild" << ChildNo << "Same\n";
+}
+
 void CheckPatternPredicateMatcher::
 printImpl(raw_ostream &OS, unsigned indent) const {
   OS.indent(indent) << "CheckPatternPredicate " << Predicate << '\n';

llvm/utils/TableGen/DAGISelMatcher.h

@@ -55,6 +55,7 @@ public:
 
     // Predicate checking.
     CheckSame,            // Fail if not same as prev match.
+    CheckChildSame,       // Fail if child not same as prev match.
     CheckPatternPredicate,
     CheckPredicate,       // Fail if node predicate fails.
     CheckOpcode,          // Fail if not opcode.
@@ -122,6 +123,7 @@ public:
     switch (getKind()) {
     default: return false;
     case CheckSame:
+    case CheckChildSame:
     case CheckPatternPredicate:
     case CheckPredicate:
     case CheckOpcode:
@@ -392,6 +394,34 @@ private:
   virtual unsigned getHashImpl() const { return getMatchNumber(); }
 };
 
+/// CheckChildSameMatcher - This checks to see if child node is exactly the same
+/// node as the specified match that was recorded with 'Record'.  This is used
+/// when patterns have the same name in them, like '(mul GPR:$in, GPR:$in)'.
+class CheckChildSameMatcher : public Matcher {
+  unsigned ChildNo;
+  unsigned MatchNumber;
+public:
+  CheckChildSameMatcher(unsigned childno, unsigned matchnumber)
+    : Matcher(CheckChildSame), ChildNo(childno), MatchNumber(matchnumber) {}
+
+  unsigned getChildNo() const { return ChildNo; }
+  unsigned getMatchNumber() const { return MatchNumber; }
+
+  static inline bool classof(const Matcher *N) {
+    return N->getKind() == CheckChildSame;
+  }
+
+  virtual bool isSafeToReorderWithPatternPredicate() const { return true; }
+
+private:
+  virtual void printImpl(raw_ostream &OS, unsigned indent) const;
+  virtual bool isEqualImpl(const Matcher *M) const {
+    return cast<CheckChildSameMatcher>(M)->ChildNo == ChildNo &&
+           cast<CheckChildSameMatcher>(M)->MatchNumber == MatchNumber;
+  }
+  virtual unsigned getHashImpl() const { return (MatchNumber << 2) | ChildNo; }
+};
+
 /// CheckPatternPredicateMatcher - This checks the target-specific predicate
 /// to see if the entire pattern is capable of matching.  This predicate does
 /// not take a node as input.  This is used for subtarget feature checks etc.

llvm/utils/TableGen/DAGISelMatcherEmitter.cpp

@@ -242,6 +242,12 @@ EmitMatcher(const Matcher *N, unsigned Indent, unsigned CurrentIdx,
        << cast<CheckSameMatcher>(N)->getMatchNumber() << ",\n";
     return 2;
 
+  case Matcher::CheckChildSame:
+    OS << "OPC_CheckChild"
+       << cast<CheckChildSameMatcher>(N)->getChildNo() << "Same, "
+       << cast<CheckChildSameMatcher>(N)->getMatchNumber() << ",\n";
+    return 2;
+
   case Matcher::CheckPatternPredicate: {
     StringRef Pred =cast<CheckPatternPredicateMatcher>(N)->getPredicate();
     OS << "OPC_CheckPatternPredicate, " << getPatternPredicate(Pred) << ',';
@@ -753,6 +759,7 @@ void MatcherTableEmitter::EmitHistogram(const Matcher *M,
     case Matcher::MoveChild: OS << "OPC_MoveChild"; break;
     case Matcher::MoveParent: OS << "OPC_MoveParent"; break;
     case Matcher::CheckSame: OS << "OPC_CheckSame"; break;
+    case Matcher::CheckChildSame: OS << "OPC_CheckChildSame"; break;
     case Matcher::CheckPatternPredicate:
       OS << "OPC_CheckPatternPredicate"; break;
     case Matcher::CheckPredicate: OS << "OPC_CheckPredicate"; break;

llvm/utils/TableGen/DAGISelMatcherOpt.cpp

@@ -52,6 +52,10 @@ static void ContractNodes(OwningPtr<Matcher> &MatcherPtr,
           CT->getResNo() == 0)     // CheckChildType checks res #0
         New = new CheckChildTypeMatcher(MC->getChildNo(), CT->getType());
 
+    if (CheckSameMatcher *CS = dyn_cast<CheckSameMatcher>(MC->getNext()))
+      if (MC->getChildNo() < 4)  // Only have CheckChildSame0...3
+        New = new CheckChildSameMatcher(MC->getChildNo(), CS->getMatchNumber());
+
     if (New) {
       // Insert the new node.
       New->setNext(MatcherPtr.take());