1 files changed, 70 insertions, 74 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 306a659c983..daf141bfcec 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -4858,19 +4858,6 @@ static bool ShouldXformToMOVLP(SDNode *V1, SDNode *V2,
   return true;
 }
 
-/// isSplatVector - Returns true if N is a BUILD_VECTOR node whose elements are
-/// all the same.
-static bool isSplatVector(SDNode *N) {
-  if (N->getOpcode() != ISD::BUILD_VECTOR)
-    return false;
-
-  SDValue SplatValue = N->getOperand(0);
-  for (unsigned i = 1, e = N->getNumOperands(); i != e; ++i)
-    if (N->getOperand(i) != SplatValue)
-      return false;
-  return true;
-}
-
 /// isZeroShuffle - Returns true if N is a VECTOR_SHUFFLE that can be resolved
 /// to an zero vector.
 /// FIXME: move to dag combiner / method on ShuffleVectorSDNode
@@ -5779,18 +5766,22 @@ static SDValue LowerVectorBroadcast(SDValue Op, const X86Subtarget* Subtarget,
       return SDValue();
 
     case ISD::BUILD_VECTOR: {
-      // The BUILD_VECTOR node must be a splat.
-      if (!isSplatVector(Op.getNode()))
+      auto *BVOp = cast<BuildVectorSDNode>(Op.getNode());
+      BitVector UndefElements;
+      SDValue Splat = BVOp->getSplatValue(&UndefElements);
+
+      // We need a splat of a single value to use broadcast, and it doesn't
+      // make any sense if the value is only in one element of the vector.
+      if (!Splat || (VT.getVectorNumElements() - UndefElements.count()) <= 1)
         return SDValue();
 
-      Ld = Op.getOperand(0);
+      Ld = Splat;
       ConstSplatVal = (Ld.getOpcode() == ISD::Constant ||
-                     Ld.getOpcode() == ISD::ConstantFP);
+                       Ld.getOpcode() == ISD::ConstantFP);
 
-      // The suspected load node has several users. Make sure that all
-      // of its users are from the BUILD_VECTOR node.
-      // Constants may have multiple users.
-      if (!ConstSplatVal && !Ld->hasNUsesOfValue(VT.getVectorNumElements(), 0))
+      // Make sure that all of the users of a non-constant load are from the
+      // BUILD_VECTOR node.
+      if (!ConstSplatVal && !BVOp->isOnlyUserOf(Ld.getNode()))
         return SDValue();
       break;
     }
@@ -9375,8 +9366,13 @@ X86TargetLowering::LowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG) const {
   bool Commuted = false;
   // FIXME: This should also accept a bitcast of a splat?  Be careful, not
   // 1,1,1,1 -> v8i16 though.
-  V1IsSplat = isSplatVector(V1.getNode());
-  V2IsSplat = isSplatVector(V2.getNode());
+  BitVector UndefElements;
+  if (auto *BVOp = dyn_cast<BuildVectorSDNode>(V1.getNode()))
+    if (BVOp->getConstantSplatNode(&UndefElements) && UndefElements.none())
+      V1IsSplat = true;
+  if (auto *BVOp = dyn_cast<BuildVectorSDNode>(V2.getNode()))
+    if (BVOp->getConstantSplatNode(&UndefElements) && UndefElements.none())
+      V2IsSplat = true;
 
   // Canonicalize the splat or undef, if present, to be on the RHS.
   if (!V2IsUndef && V1IsSplat && !V2IsSplat) {
@@ -15171,10 +15167,9 @@ static SDValue LowerScalarImmediateShift(SDValue Op, SelectionDAG &DAG,
   SDValue Amt = Op.getOperand(1);
 
   // Optimize shl/srl/sra with constant shift amount.
-  if (isSplatVector(Amt.getNode())) {
-    SDValue SclrAmt = Amt->getOperand(0);
-    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(SclrAmt)) {
-      uint64_t ShiftAmt = C->getZExtValue();
+  if (auto *BVAmt = dyn_cast<BuildVectorSDNode>(Amt)) {
+    if (auto *ShiftConst = BVAmt->getConstantSplatNode()) {
+      uint64_t ShiftAmt = ShiftConst->getZExtValue();
 
       if (VT == MVT::v2i64 || VT == MVT::v4i32 || VT == MVT::v8i16 ||
           (Subtarget->hasInt256() &&
@@ -19423,28 +19418,34 @@ static SDValue PerformSELECTCombine(SDNode *N, SelectionDAG &DAG,
           Other->getOpcode() == ISD::SUB && DAG.isEqualTo(OpRHS, CondRHS))
         return DAG.getNode(X86ISD::SUBUS, DL, VT, OpLHS, OpRHS);
 
-      // If the RHS is a constant we have to reverse the const canonicalization.
-      // x > C-1 ? x+-C : 0 --> subus x, C
-      if (CC == ISD::SETUGT && Other->getOpcode() == ISD::ADD &&
-          isSplatVector(CondRHS.getNode()) && isSplatVector(OpRHS.getNode())) {
-        APInt A = cast<ConstantSDNode>(OpRHS.getOperand(0))->getAPIntValue();
-        if (CondRHS.getConstantOperandVal(0) == -A-1)
-          return DAG.getNode(X86ISD::SUBUS, DL, VT, OpLHS,
-                             DAG.getConstant(-A, VT));
-      }
-
-      // Another special case: If C was a sign bit, the sub has been
-      // canonicalized into a xor.
-      // FIXME: Would it be better to use computeKnownBits to determine whether
-      //        it's safe to decanonicalize the xor?
-      // x s< 0 ? x^C : 0 --> subus x, C
-      if (CC == ISD::SETLT && Other->getOpcode() == ISD::XOR &&
-          ISD::isBuildVectorAllZeros(CondRHS.getNode()) &&
-          isSplatVector(OpRHS.getNode())) {
-        APInt A = cast<ConstantSDNode>(OpRHS.getOperand(0))->getAPIntValue();
-        if (A.isSignBit())
-          return DAG.getNode(X86ISD::SUBUS, DL, VT, OpLHS, OpRHS);
-      }
+      if (auto *OpRHSBV = dyn_cast<BuildVectorSDNode>(OpRHS))
+        if (auto *OpRHSConst = OpRHSBV->getConstantSplatNode()) {
+          if (auto *CondRHSBV = dyn_cast<BuildVectorSDNode>(CondRHS))
+            if (auto *CondRHSConst = CondRHSBV->getConstantSplatNode())
+              // If the RHS is a constant we have to reverse the const
+              // canonicalization.
+              // x > C-1 ? x+-C : 0 --> subus x, C
+              if (CC == ISD::SETUGT && Other->getOpcode() == ISD::ADD &&
+                  CondRHSConst->getAPIntValue() ==
+                      (-OpRHSConst->getAPIntValue() - 1))
+                return DAG.getNode(
+                    X86ISD::SUBUS, DL, VT, OpLHS,
+                    DAG.getConstant(-OpRHSConst->getAPIntValue(), VT));
+
+          // Another special case: If C was a sign bit, the sub has been
+          // canonicalized into a xor.
+          // FIXME: Would it be better to use computeKnownBits to determine
+          //        whether it's safe to decanonicalize the xor?
+          // x s< 0 ? x^C : 0 --> subus x, C
+          if (CC == ISD::SETLT && Other->getOpcode() == ISD::XOR &&
+              ISD::isBuildVectorAllZeros(CondRHS.getNode()) &&
+              OpRHSConst->getAPIntValue().isSignBit())
+            // Note that we have to rebuild the RHS constant here to ensure we
+            // don't rely on particular values of undef lanes.
+            return DAG.getNode(
+                X86ISD::SUBUS, DL, VT, OpLHS,
+                DAG.getConstant(OpRHSConst->getAPIntValue(), VT));
+        }
     }
   }
 
@@ -20152,16 +20153,15 @@ static SDValue PerformSHLCombine(SDNode *N, SelectionDAG &DAG) {
   // vector operations in many cases. Also, on sandybridge ADD is faster than
   // shl.
   // (shl V, 1) -> add V,V
-  if (isSplatVector(N1.getNode())) {
-    assert(N0.getValueType().isVector() && "Invalid vector shift type");
-    ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1->getOperand(0));
-    // We shift all of the values by one. In many cases we do not have
-    // hardware support for this operation. This is better expressed as an ADD
-    // of two values.
-    if (N1C && (1 == N1C->getZExtValue())) {
-      return DAG.getNode(ISD::ADD, SDLoc(N), VT, N0, N0);
+  if (auto *N1BV = dyn_cast<BuildVectorSDNode>(N1))
+    if (auto *N1SplatC = N1BV->getConstantSplatNode()) {
+      assert(N0.getValueType().isVector() && "Invalid vector shift type");
+      // We shift all of the values by one. In many cases we do not have
+      // hardware support for this operation. This is better expressed as an ADD
+      // of two values.
+      if (N1SplatC->getZExtValue() == 1)
+        return DAG.getNode(ISD::ADD, SDLoc(N), VT, N0, N0);
     }
-  }
 
   return SDValue();
 }
@@ -20180,10 +20180,9 @@ static SDValue performShiftToAllZeros(SDNode *N, SelectionDAG &DAG,
 
   SDValue Amt = N->getOperand(1);
   SDLoc DL(N);
-  if (isSplatVector(Amt.getNode())) {
-    SDValue SclrAmt = Amt->getOperand(0);
-    if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(SclrAmt)) {
-      APInt ShiftAmt = C->getAPIntValue();
+  if (auto *AmtBV = dyn_cast<BuildVectorSDNode>(Amt))
+    if (auto *AmtSplat = AmtBV->getConstantSplatNode()) {
+      APInt ShiftAmt = AmtSplat->getAPIntValue();
       unsigned MaxAmount = VT.getVectorElementType().getSizeInBits();
 
       // SSE2/AVX2 logical shifts always return a vector of 0s
@@ -20193,7 +20192,6 @@ static SDValue performShiftToAllZeros(SDNode *N, SelectionDAG &DAG,
       if (ShiftAmt.trunc(8).uge(MaxAmount))
         return getZeroVector(VT, Subtarget, DAG, DL);
     }
-  }
 
   return SDValue();
 }
@@ -20387,9 +20385,10 @@ static SDValue WidenMaskArithmetic(SDNode *N, SelectionDAG &DAG,
 
   // The right side has to be a 'trunc' or a constant vector.
   bool RHSTrunc = N1.getOpcode() == ISD::TRUNCATE;
-  bool RHSConst = (isSplatVector(N1.getNode()) &&
-                   isa<ConstantSDNode>(N1->getOperand(0)));
-  if (!RHSTrunc && !RHSConst)
+  ConstantSDNode *RHSConstSplat;
+  if (auto *RHSBV = dyn_cast<BuildVectorSDNode>(N1))
+    RHSConstSplat = RHSBV->getConstantSplatNode();
+  if (!RHSTrunc && !RHSConstSplat)
     return SDValue();
 
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
@@ -20399,9 +20398,9 @@ static SDValue WidenMaskArithmetic(SDNode *N, SelectionDAG &DAG,
 
   // Set N0 and N1 to hold the inputs to the new wide operation.
   N0 = N0->getOperand(0);
-  if (RHSConst) {
+  if (RHSConstSplat) {
     N1 = DAG.getNode(ISD::ZERO_EXTEND, DL, WideVT.getScalarType(),
-                     N1->getOperand(0));
+                     SDValue(RHSConstSplat, 0));
     SmallVector<SDValue, 8> C(WideVT.getVectorNumElements(), N1);
     N1 = DAG.getNode(ISD::BUILD_VECTOR, DL, WideVT, C);
   } else if (RHSTrunc) {
@@ -20547,12 +20546,9 @@ static SDValue PerformOrCombine(SDNode *N, SelectionDAG &DAG,
       unsigned EltBits = MaskVT.getVectorElementType().getSizeInBits();
       unsigned SraAmt = ~0;
       if (Mask.getOpcode() == ISD::SRA) {
-        SDValue Amt = Mask.getOperand(1);
-        if (isSplatVector(Amt.getNode())) {
-          SDValue SclrAmt = Amt->getOperand(0);
-          if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(SclrAmt))
-            SraAmt = C->getZExtValue();
-        }
+        if (auto *AmtBV = dyn_cast<BuildVectorSDNode>(Mask.getOperand(1)))
+          if (auto *AmtConst = AmtBV->getConstantSplatNode())
+            SraAmt = AmtConst->getZExtValue();
       } else if (Mask.getOpcode() == X86ISD::VSRAI) {
         SDValue SraC = Mask.getOperand(1);
         SraAmt  = cast<ConstantSDNode>(SraC)->getZExtValue();