[SelectionDAG] move constant or splat functions to common location

rL347502 moved the null sibling, so we should group all of these
together. I'm not sure why these aren't methods of the SDValue
class itself, but that's another patch if that's possible.

llvm-svn: 347523

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

@@ -1613,11 +1613,21 @@ ConstantSDNode *isConstOrConstSplat(SDValue N, bool AllowUndefs = false);
 /// Returns the SDNode if it is a constant splat BuildVector or constant float.
 ConstantFPSDNode *isConstOrConstSplatFP(SDValue N, bool AllowUndefs = false);
 
-/// Determines if it is a constant null integer or a splatted vector of a
-/// constant null integer (with no undefs).
+/// Return true if the value is a constant 0 integer or a splatted vector of
+/// a constant 0 integer (with no undefs).
 /// Build vector implicit truncation is not an issue for null values.
 bool isNullOrNullSplat(SDValue V);
 
+/// Return true if the value is a constant 1 integer or a splatted vector of a
+/// constant 1 integer (with no undefs).
+/// Does not permit build vector implicit truncation.
+bool isOneOrOneSplat(SDValue V);
+
+/// Return true if the value is a constant -1 integer or a splatted vector of a
+/// constant -1 integer (with no undefs).
+/// Does not permit build vector implicit truncation.
+bool isAllOnesOrAllOnesSplat(SDValue V);
+
 class GlobalAddressSDNode : public SDNode {
   friend class SelectionDAG;
 

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -911,29 +911,6 @@ static bool isConstantOrConstantVector(SDValue N, bool NoOpaques = false) {
   return true;
 }
 
-// Determines if it is a constant integer of one or a splatted vector of a
-// constant integer of one (with no undefs).
-// Do not permit build vector implicit truncation.
-static bool isOneConstantOrOneSplatConstant(SDValue N) {
-  // TODO: may want to use peekThroughBitcast() here.
-  unsigned BitWidth = N.getScalarValueSizeInBits();
-  if (ConstantSDNode *Splat = isConstOrConstSplat(N))
-    return Splat->isOne() && Splat->getAPIntValue().getBitWidth() == BitWidth;
-  return false;
-}
-
-// Determines if it is a constant integer of all ones or a splatted vector of a
-// constant integer of all ones (with no undefs).
-// Do not permit build vector implicit truncation.
-static bool isAllOnesConstantOrAllOnesSplatConstant(SDValue N) {
-  N = peekThroughBitcasts(N);
-  unsigned BitWidth = N.getScalarValueSizeInBits();
-  if (ConstantSDNode *Splat = isConstOrConstSplat(N))
-    return Splat->isAllOnesValue() &&
-           Splat->getAPIntValue().getBitWidth() == BitWidth;
-  return false;
-}
-
 // Determines if a BUILD_VECTOR is composed of all-constants possibly mixed with
 // undef's.
 static bool isAnyConstantBuildVector(const SDNode *N) {
@@ -1911,11 +1888,10 @@ SDValue DAGCombiner::foldBinOpIntoSelect(SDNode *BO) {
   // and (select Cond, 0, -1), X --> select Cond, 0, X
   // or X, (select Cond, -1, 0) --> select Cond, -1, X
   auto BinOpcode = BO->getOpcode();
-  bool CanFoldNonConst = (BinOpcode == ISD::AND || BinOpcode == ISD::OR) &&
-                         (isNullOrNullSplat(CT) ||
-                          isAllOnesConstantOrAllOnesSplatConstant(CT)) &&
-                         (isNullOrNullSplat(CF) ||
-                          isAllOnesConstantOrAllOnesSplatConstant(CF));
+  bool CanFoldNonConst =
+      (BinOpcode == ISD::AND || BinOpcode == ISD::OR) &&
+      (isNullOrNullSplat(CT) || isAllOnesOrAllOnesSplat(CT)) &&
+      (isNullOrNullSplat(CF) || isAllOnesOrAllOnesSplat(CF));
 
   SDValue CBO = BO->getOperand(SelOpNo ^ 1);
   if (!CanFoldNonConst &&
@@ -2084,7 +2060,7 @@ SDValue DAGCombiner::visitADD(SDNode *N) {
     //   add (zext i1 X), -1 -> sext (not i1 X)
     // because most (?) targets generate better code for the zext form.
     if (N0.getOpcode() == ISD::SIGN_EXTEND && N0.hasOneUse() &&
-        isOneConstantOrOneSplatConstant(N1)) {
+        isOneOrOneSplat(N1)) {
       SDValue X = N0.getOperand(0);
       if ((!LegalOperations ||
            (TLI.isOperationLegal(ISD::XOR, X.getValueType()) &&
@@ -2175,7 +2151,7 @@ SDValue DAGCombiner::visitADD(SDNode *N) {
     return DAG.getNode(ISD::OR, DL, VT, N0, N1);
 
   // fold (add (xor a, -1), 1) -> (sub 0, a)
-  if (isBitwiseNot(N0) && isOneConstantOrOneSplatConstant(N1))
+  if (isBitwiseNot(N0) && isOneOrOneSplat(N1))
     return DAG.getNode(ISD::SUB, DL, VT, DAG.getConstant(0, DL, VT),
                        N0.getOperand(0));
 
@@ -2245,8 +2221,7 @@ SDValue DAGCombiner::visitADDLike(SDValue N0, SDValue N1, SDNode *LocReference)
 
     // (add z, (and (sbbl x, x), 1)) -> (sub z, (sbbl x, x))
     // and similar xforms where the inner op is either ~0 or 0.
-    if (NumSignBits == DestBits &&
-        isOneConstantOrOneSplatConstant(N1->getOperand(1)))
+    if (NumSignBits == DestBits && isOneOrOneSplat(N1->getOperand(1)))
       return DAG.getNode(ISD::SUB, DL, VT, N0, AndOp0);
   }
 
@@ -2377,7 +2352,7 @@ SDValue DAGCombiner::visitUADDO(SDNode *N) {
                      DAG.getConstant(0, DL, CarryVT));
 
   // fold (uaddo (xor a, -1), 1) -> (usub 0, a) and flip carry.
-  if (isBitwiseNot(N0) && isOneConstantOrOneSplatConstant(N1)) {
+  if (isBitwiseNot(N0) && isOneOrOneSplat(N1)) {
     SDValue Sub = DAG.getNode(ISD::USUBO, DL, N->getVTList(),
                               DAG.getConstant(0, DL, VT),
                               N0.getOperand(0));
@@ -2613,7 +2588,7 @@ SDValue DAGCombiner::visitSUB(SDNode *N) {
   }
 
   // Canonicalize (sub -1, x) -> ~x, i.e. (xor x, -1)
-  if (isAllOnesConstantOrAllOnesSplatConstant(N0))
+  if (isAllOnesOrAllOnesSplat(N0))
     return DAG.getNode(ISD::XOR, DL, VT, N1, N0);
 
   // fold (A - (0-B)) -> A+B
@@ -3899,7 +3874,7 @@ SDValue DAGCombiner::foldLogicOfSetCCs(bool IsAnd, SDValue N0, SDValue N1,
   bool IsInteger = OpVT.isInteger();
   if (LR == RR && CC0 == CC1 && IsInteger) {
     bool IsZero = isNullOrNullSplat(LR);
-    bool IsNeg1 = isAllOnesConstantOrAllOnesSplatConstant(LR);
+    bool IsNeg1 = isAllOnesOrAllOnesSplat(LR);
 
     // All bits clear?
     bool AndEqZero = IsAnd && CC1 == ISD::SETEQ && IsZero;
@@ -5946,7 +5921,7 @@ SDValue DAGCombiner::unfoldMaskedMerge(SDNode *N) {
   assert(N->getOpcode() == ISD::XOR);
 
   // Don't touch 'not' (i.e. where y = -1).
-  if (isAllOnesConstantOrAllOnesSplatConstant(N->getOperand(1)))
+  if (isAllOnesOrAllOnesSplat(N->getOperand(1)))
     return SDValue();
 
   EVT VT = N->getValueType(0);
@@ -5963,7 +5938,7 @@ SDValue DAGCombiner::unfoldMaskedMerge(SDNode *N) {
     SDValue Xor0 = Xor.getOperand(0);
     SDValue Xor1 = Xor.getOperand(1);
     // Don't touch 'not' (i.e. where y = -1).
-    if (isAllOnesConstantOrAllOnesSplatConstant(Xor1))
+    if (isAllOnesOrAllOnesSplat(Xor1))
       return false;
     if (Other == Xor0)
       std::swap(Xor0, Xor1);

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -8381,8 +8381,22 @@ ConstantFPSDNode *llvm::isConstOrConstSplatFP(SDValue N, bool AllowUndefs) {
 
 bool llvm::isNullOrNullSplat(SDValue N) {
   // TODO: may want to use peekThroughBitcast() here.
-  ConstantSDNode *Splat = isConstOrConstSplat(N);
-  return Splat && Splat->isNullValue();
+  ConstantSDNode *C = isConstOrConstSplat(N);
+  return C && C->isNullValue();
+}
+
+bool llvm::isOneOrOneSplat(SDValue N) {
+  // TODO: may want to use peekThroughBitcast() here.
+  unsigned BitWidth = N.getScalarValueSizeInBits();
+  ConstantSDNode *C = isConstOrConstSplat(N);
+  return C && C->isOne() && C->getValueSizeInBits(0) == BitWidth;
+}
+
+bool llvm::isAllOnesOrAllOnesSplat(SDValue N) {
+  N = peekThroughBitcasts(N);
+  unsigned BitWidth = N.getScalarValueSizeInBits();
+  ConstantSDNode *C = isConstOrConstSplat(N);
+  return C && C->isAllOnesValue() && C->getValueSizeInBits(0) == BitWidth;
 }
 
 HandleSDNode::~HandleSDNode() {