[AIE2] Helper function for creating VSHUFFLE instructions

Author: ValentijnvdBeek

llvm/lib/Target/AIE/AIE2PreLegalizerCombiner.cpp

@@ -152,6 +152,39 @@ bool AIE2PreLegalizerCombinerImpl::tryToCombineIntrinsic(
   return false;
 }
 
+bool createVShuffle(MachineInstr &MI, const LLT TargetTy, const uint8_t Mode) {
+  MachineIRBuilder MIB(MI);
+  MachineRegisterInfo &MRI = *MIB.getMRI();
+  const Register DstReg = MI.getOperand(0).getReg();
+  const LLT DstTy = MRI.getType(DstReg);
+
+  if (DstTy != TargetTy)
+    return false;
+
+  const Register Src1 = MI.getOperand(1).getReg();
+  const Register Src2 = MI.getOperand(2).getReg();
+  const Register ShuffleModeReg =
+      MRI.createGenericVirtualRegister(LLT::scalar(32));
+
+  // This combiner only cares about the lower bits, so we can pad the
+  // vector to cover the case where two separate vectors are shuffled.
+  // together
+  MIB.buildConstant(ShuffleModeReg, Mode);
+  if (MRI.getType(Src1) == TargetTy) {
+    MIB.buildInstr(AIE2::G_AIE_VSHUFFLE, {DstReg},
+                   {Src1, Src2, ShuffleModeReg});
+  } else {
+    // We reuse the same register since we ignore the high part of the vector
+    const Register TmpRegister = MRI.createGenericVirtualRegister(TargetTy);
+    MIB.buildConcatVectors(TmpRegister, {Src1, Src2});
+    MIB.buildInstr(AIE2::G_AIE_VSHUFFLE, {DstReg},
+                   {TmpRegister, TmpRegister, ShuffleModeReg});
+  }
+
+  MI.eraseFromParent();
+  return true;
+}
+
 CombinerHelper::GeneratorType sectionGenerator(const int32_t From,
                                                const int32_t To,
                                                const int32_t Partitions,

llvm/lib/Target/AIE/AIEInstrGISel.td

@@ -96,6 +96,12 @@ def G_AIE_BROADCAST_VECTOR : AIEGenericInstruction {
   let hasSideEffects = false;
 }
 
+def G_AIE_VSHUFFLE : AIEGenericInstruction {
+  let OutOperandList = (outs type0:$dst);
+  let InOperandList = (ins type0:$src1, type0:$src2, type1:$mode);
+  let hasSideEffects = false;
+}
+
 // Create a larger vector by padding undefined values in the high bits
 def G_AIE_PAD_VECTOR_UNDEF : AIEGenericInstruction {
   let OutOperandList = (outs type0:$dst);