Revert r305465: [X86][AVX512] Improve lowering of AVX512 compare intr…

…insics (remove redundant shift left+right instructions).

This is causing windows buildbot failures

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305470 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86ISelLowering.cpp

@@ -5059,20 +5059,6 @@ static SDValue insert256BitVector(SDValue Result, SDValue Vec, unsigned IdxVal,
   return insertSubVector(Result, Vec, IdxVal, DAG, dl, 256);
 }
 
-// Return true if the instruction zeroes the unused upper part of the
-// destination and accepts mask.
-static bool isMaskedZeroUpperBitsvXi1(unsigned int Opcode) {
-  switch (Opcode) {
-  default:
-    return false;
-  case X86ISD::PCMPEQM:
-  case X86ISD::PCMPGTM:
-  case X86ISD::CMPM:
-  case X86ISD::CMPMU:
-    return true;
-  }
-}
-
 /// Insert i1-subvector to i1-vector.
 static SDValue insert1BitVector(SDValue Op, SelectionDAG &DAG,
                                 const X86Subtarget &Subtarget) {
@@ -5105,22 +5091,6 @@ static SDValue insert1BitVector(SDValue Op, SelectionDAG &DAG,
   // 3. Subvector should be inserted in the middle (for example v2i1
   //    to v16i1, index 2)
 
-  // If this node widens - by concatenating zeroes - the type of the result
-  // of a node with instruction that zeroes all upper (irrelevant) bits of the
-  // output register, mark this node as legal to enable replacing them with
-  // the v8i1 version of the previous instruction during instruction selection.
-  // For example, VPCMPEQDZ128rr instruction stores its v4i1 result in a k-reg,
-  // while zeroing all the upper remaining 60 bits of the register. if the
-  // result of such instruction is inserted into an allZeroVector, then we can
-  // safely remove insert_vector (in instruction selection) as the cmp instr
-  // already zeroed the rest of the register.
-  if (ISD::isBuildVectorAllZeros(Vec.getNode()) && IdxVal == 0 &&
-      (isMaskedZeroUpperBitsvXi1(SubVec.getOpcode()) ||
-       (SubVec.getOpcode() == ISD::AND &&
-        (isMaskedZeroUpperBitsvXi1(SubVec.getOperand(0).getOpcode()) ||
-         isMaskedZeroUpperBitsvXi1(SubVec.getOperand(1).getOpcode())))))
-    return Op;
-
   // extend to natively supported kshift
   MVT MinVT = Subtarget.hasDQI() ? MVT::v8i1 : MVT::v16i1;
   MVT WideOpVT = OpVT;
@@ -7943,60 +7913,6 @@ static SDValue LowerAVXCONCAT_VECTORS(SDValue Op, SelectionDAG &DAG) {
   return concat256BitVectors(V1, V2, ResVT, NumElems, DAG, dl);
 }
 
-// Return true if all the operands of the given CONCAT_VECTORS node are zeros
-// except for the first one. (CONCAT_VECTORS Op, 0, 0,...,0)
-static bool isExpandWithZeros(const SDValue &Op) {
-  assert(Op.getOpcode() == ISD::CONCAT_VECTORS &&
-         "Expand with zeros only possible in CONCAT_VECTORS nodes!");
-
-  for (unsigned i = 1; i < Op.getNumOperands(); i++)
-    if (!ISD::isBuildVectorAllZeros(Op.getOperand(i).getNode()))
-      return false;
-
-  return true;
-}
-
-// Returns true if the given node is a type promotion (by concatenating i1
-// zeros) of the result of a node that already zeros all upper bits of
-// k-register.
-static SDValue isTypePromotionOfi1ZeroUpBits(SDValue Op) {
-  unsigned Opc = Op.getOpcode();
-
-  assert(Opc == ISD::CONCAT_VECTORS &&
-         Op.getSimpleValueType().getVectorElementType() == MVT::i1 &&
-         "Unexpected node to check for type promotion!");
-
-  // As long as we are concatenating zeros to the upper part of a previous node
-  // result, climb up the tree until a node with different opcode is
-  // encountered
-  while (Opc == ISD::INSERT_SUBVECTOR || Opc == ISD::CONCAT_VECTORS) {
-    if (Opc == ISD::INSERT_SUBVECTOR) {
-      if (ISD::isBuildVectorAllZeros(Op.getOperand(0).getNode()) &&
-          Op.getConstantOperandVal(2) == 0)
-        Op = Op.getOperand(1);
-      else
-        return SDValue();
-    } else { // Opc == ISD::CONCAT_VECTORS
-      if (isExpandWithZeros(Op))
-        Op = Op.getOperand(0);
-      else
-        return SDValue();
-    }
-    Opc = Op.getOpcode();
-  }
-
-  // Check if the first inserted node zeroes the upper bits, or an 'and' result
-  // of a node that zeros the upper bits (its masked version).
-  if (isMaskedZeroUpperBitsvXi1(Op.getOpcode()) ||
-      (Op.getOpcode() == ISD::AND &&
-       (isMaskedZeroUpperBitsvXi1(Op.getOperand(0).getOpcode()) ||
-        isMaskedZeroUpperBitsvXi1(Op.getOperand(1).getOpcode())))) {
-    return Op;
-  }
-
-  return SDValue();
-}
-
 static SDValue LowerCONCAT_VECTORSvXi1(SDValue Op,
                                        const X86Subtarget &Subtarget,
                                        SelectionDAG & DAG) {
@@ -8007,17 +7923,6 @@ static SDValue LowerCONCAT_VECTORSvXi1(SDValue Op,
   assert(isPowerOf2_32(NumOfOperands) &&
          "Unexpected number of operands in CONCAT_VECTORS");
 
-  // If this node promotes - by concatenating zeroes - the type of the result
-  // of a node with instruction that zeroes all upper (irrelevant) bits of the
-  // output register, mark it as legal and catch the pattern in instruction
-  // selection to avoid emitting extra insturctions (for zeroing upper bits).
-  if (SDValue Promoted = isTypePromotionOfi1ZeroUpBits(Op)) {
-    SDValue ZeroC = DAG.getConstant(0, dl, MVT::i64);
-    SDValue AllZeros = DAG.getSplatBuildVector(ResVT, dl, ZeroC);
-    return DAG.getNode(ISD::INSERT_SUBVECTOR, dl, ResVT, AllZeros, Promoted,
-                       ZeroC);
-  }
-
   SDValue Undef = DAG.getUNDEF(ResVT);
   if (NumOfOperands > 2) {
     // Specialize the cases when all, or all but one, of the operands are undef.