[RISCV] Add SDNode patterns for vandn.[vv,vx]

Unfortunately we can't use the standard splat_vector and vnot PatFrags because
they are preprocessed to vmv.v.x's, so we need to define helpers to catch
those. We can't use SplatPat either because we need to nest another fragment
inside of it.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D155433

Author: lukel97

llvm/lib/Target/RISCV/RISCVInstrInfoZvk.td

@@ -182,6 +182,8 @@ let Predicates = [HasStdExtZvksh], RVVConstraint = NoConstraint in {
 // Pseudo instructions
 //===----------------------------------------------------------------------===//
 
+defm PseudoVANDN : VPseudoVALU_VV_VX;
+
 multiclass VPseudoUnaryV_V {
   foreach m = MxList in {
     let VLMul = m.value in {
@@ -215,6 +217,34 @@ multiclass VPatUnarySDNode_V<SDPatternOperator op, string instruction_name> {
   }
 }
 
+// Helpers for detecting splats since we preprocess splat_vector to vmv.v.x
+// This should match the logic in RISCVDAGToDAGISel::selectVSplat
+def riscv_splat_vector : PatFrag<(ops node:$rs1),
+                                 (riscv_vmv_v_x_vl undef, node:$rs1, srcvalue)>;
+def riscv_vnot : PatFrag<(ops node:$rs1), (xor node:$rs1,
+                                               (riscv_splat_vector -1))>;
+
+foreach vti = AllIntegerVectors in {
+  let Predicates = !listconcat([HasStdExtZvbb],
+                               GetVTypePredicates<vti>.Predicates) in {
+    def : Pat<(vti.Vector (and (riscv_vnot vti.RegClass:$rs1),
+                               vti.RegClass:$rs2)),
+              (!cast<Instruction>("PseudoVANDN_VV_"#vti.LMul.MX)
+                 (vti.Vector (IMPLICIT_DEF)),
+                 vti.RegClass:$rs2,
+                 vti.RegClass:$rs1,
+                 vti.AVL, vti.Log2SEW, TA_MA)>;
+    def : Pat<(vti.Vector (and (riscv_splat_vector
+                                 (not vti.ScalarRegClass:$rs1)),
+                               vti.RegClass:$rs2)),
+              (!cast<Instruction>("PseudoVANDN_VX_"#vti.LMul.MX)
+                 (vti.Vector (IMPLICIT_DEF)),
+                 vti.RegClass:$rs2,
+                 vti.ScalarRegClass:$rs1,
+                 vti.AVL, vti.Log2SEW, TA_MA)>;
+  }
+}
+
 defm : VPatUnarySDNode_V<bitreverse, "PseudoVBREV">;
 defm : VPatUnarySDNode_V<bswap, "PseudoVREV8">;
 defm : VPatUnarySDNode_V<ctlz, "PseudoVCLZ">;