[LLVM][AArch64] Fix invalid use of AArch64ISD::UZP2 in performConcatVectorsCombine. (llvm#104774)

UZP2 requires both operands to match the result type but the combine tries to replace a truncate by passing the pre-truncated operands directly to an UZP2 with the truncated result type. This patch nop-casts the operands to keep the DAG consistent.  There should be no changes to the generated code, which is fine as it.

This patch also enables more target specific getNode() validation for fixed length vector types.

Author: paulwalker-arm

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -19852,15 +19852,15 @@ static SDValue performConcatVectorsCombine(SDNode *N,
     // This optimization reduces instruction count.
     if (N00Opc == AArch64ISD::VLSHR && N10Opc == AArch64ISD::VLSHR &&
         N00->getOperand(1) == N10->getOperand(1)) {
-
       SDValue N000 = N00->getOperand(0);
       SDValue N100 = N10->getOperand(0);
       uint64_t N001ConstVal = N00->getConstantOperandVal(1),
                N101ConstVal = N10->getConstantOperandVal(1),
                NScalarSize = N->getValueType(0).getScalarSizeInBits();
 
       if (N001ConstVal == N101ConstVal && N001ConstVal > NScalarSize) {
-
+        N000 = DAG.getNode(AArch64ISD::NVCAST, dl, VT, N000);
+        N100 = DAG.getNode(AArch64ISD::NVCAST, dl, VT, N100);
         SDValue Uzp = DAG.getNode(AArch64ISD::UZP2, dl, VT, N000, N100);
         SDValue NewShiftConstant =
             DAG.getConstant(N001ConstVal - NScalarSize, dl, MVT::i32);
@@ -29344,8 +29344,10 @@ void AArch64TargetLowering::verifyTargetSDNode(const SDNode *N) const {
     assert(OpVT.getSizeInBits() == VT.getSizeInBits() &&
            "Expected vectors of equal size!");
     // TODO: Enable assert once bogus creations have been fixed.
-    // assert(OpVT.getVectorElementCount() == VT.getVectorElementCount()*2 &&
-    //       "Expected result vector with half the lanes of its input!");
+    if (VT.isScalableVector())
+      break;
+    assert(OpVT.getVectorElementCount() == VT.getVectorElementCount() * 2 &&
+           "Expected result vector with half the lanes of its input!");
     break;
   }
   case AArch64ISD::TRN1:
@@ -29362,7 +29364,9 @@ void AArch64TargetLowering::verifyTargetSDNode(const SDNode *N) const {
     assert(VT.isVector() && Op0VT.isVector() && Op1VT.isVector() &&
            "Expected vectors!");
     // TODO: Enable assert once bogus creations have been fixed.
-    // assert(VT == Op0VT && VT == Op1VT && "Expected matching vectors!");
+    if (VT.isScalableVector())
+      break;
+    assert(VT == Op0VT && VT == Op1VT && "Expected matching vectors!");
     break;
   }
   }