[LegalizeTypes] Legalize vector rotate operations

Lower vector rotate operations as long as the legalization occurs outside of LegalizeVectorOps.

This fixes https://bugs.llvm.org/show_bug.cgi?id=47320

Patch By: @rsanthir.quic (Ryan Santhirarajan)

Differential Revision: https://reviews.llvm.org/D89497

llvm/include/llvm/CodeGen/TargetLowering.h

@@ -4309,9 +4309,12 @@ public:
 
   /// Expand rotations.
   /// \param N Node to expand
+  /// \param AllowVectorOps expand vector rotate, this should only be performed
+  ///        if the legalization is happening outside of LegalizeVectorOps
   /// \param Result output after conversion
   /// \returns True, if the expansion was successful, false otherwise
-  bool expandROT(SDNode *N, SDValue &Result, SelectionDAG &DAG) const;
+  bool expandROT(SDNode *N, bool AllowVectorOps, SDValue &Result,
+                 SelectionDAG &DAG) const;
 
   /// Expand float(f32) to SINT(i64) conversion
   /// \param N Node to expand

llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp

@@ -3523,7 +3523,7 @@ bool SelectionDAGLegalize::ExpandNode(SDNode *Node) {
     break;
   case ISD::ROTL:
   case ISD::ROTR:
-    if (TLI.expandROT(Node, Tmp1, DAG))
+    if (TLI.expandROT(Node, true /*AllowVectorOps*/, Tmp1, DAG))
       Results.push_back(Tmp1);
     break;
   case ISD::SADDSAT:

llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp

@@ -1122,7 +1122,7 @@ SDValue DAGTypeLegalizer::PromoteIntRes_SRL(SDNode *N) {
 SDValue DAGTypeLegalizer::PromoteIntRes_Rotate(SDNode *N) {
   // Lower the rotate to shifts and ORs which can be promoted.
   SDValue Res;
-  TLI.expandROT(N, Res, DAG);
+  TLI.expandROT(N, true /*AllowVectorOps*/, Res, DAG);
   ReplaceValueWith(SDValue(N, 0), Res);
   return SDValue();
 }
@@ -4068,7 +4068,7 @@ void DAGTypeLegalizer::ExpandIntRes_Rotate(SDNode *N,
                                            SDValue &Lo, SDValue &Hi) {
   // Lower the rotate to shifts and ORs which can be expanded.
   SDValue Res;
-  TLI.expandROT(N, Res, DAG);
+  TLI.expandROT(N, true /*AllowVectorOps*/, Res, DAG);
   SplitInteger(Res, Lo, Hi);
 }
 

llvm/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp

@@ -800,7 +800,7 @@ void VectorLegalizer::Expand(SDNode *Node, SmallVectorImpl<SDValue> &Results) {
     break;
   case ISD::ROTL:
   case ISD::ROTR:
-    if (TLI.expandROT(Node, Tmp, DAG)) {
+    if (TLI.expandROT(Node, false /*AllowVectorOps*/, Tmp, DAG)) {
       Results.push_back(Tmp);
       return;
     }

llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

@@ -6302,8 +6302,8 @@ bool TargetLowering::expandFunnelShift(SDNode *Node, SDValue &Result,
 }
 
 // TODO: Merge with expandFunnelShift.
-bool TargetLowering::expandROT(SDNode *Node, SDValue &Result,
-                               SelectionDAG &DAG) const {
+bool TargetLowering::expandROT(SDNode *Node, bool AllowVectorOps,
+                               SDValue &Result, SelectionDAG &DAG) const {
   EVT VT = Node->getValueType(0);
   unsigned EltSizeInBits = VT.getScalarSizeInBits();
   bool IsLeft = Node->getOpcode() == ISD::ROTL;
@@ -6322,11 +6322,12 @@ bool TargetLowering::expandROT(SDNode *Node, SDValue &Result,
     return true;
   }
 
-  if (VT.isVector() && (!isOperationLegalOrCustom(ISD::SHL, VT) ||
-                        !isOperationLegalOrCustom(ISD::SRL, VT) ||
-                        !isOperationLegalOrCustom(ISD::SUB, VT) ||
-                        !isOperationLegalOrCustomOrPromote(ISD::OR, VT) ||
-                        !isOperationLegalOrCustomOrPromote(ISD::AND, VT)))
+  if (!AllowVectorOps && VT.isVector() &&
+      (!isOperationLegalOrCustom(ISD::SHL, VT) ||
+       !isOperationLegalOrCustom(ISD::SRL, VT) ||
+       !isOperationLegalOrCustom(ISD::SUB, VT) ||
+       !isOperationLegalOrCustomOrPromote(ISD::OR, VT) ||
+       !isOperationLegalOrCustomOrPromote(ISD::AND, VT)))
     return false;
 
   unsigned ShOpc = IsLeft ? ISD::SHL : ISD::SRL;

llvm/test/CodeGen/AArch64/expand-vector-rot.ll

@@ -0,0 +1,22 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=aarch64-linux-android | FileCheck %s
+
+declare <2 x i16> @llvm.fshl.v2i16(<2 x i16>, <2 x i16>, <2 x i16>)
+
+define <2 x i16>  @rotlv2_16(<2 x i16> %vec2_16, <2 x i16> %shift) {
+; CHECK-LABEL: rotlv2_16:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    neg v3.2s, v1.2s
+; CHECK-NEXT:    movi v4.2s, #15
+; CHECK-NEXT:    movi d2, #0x00ffff0000ffff
+; CHECK-NEXT:    and v3.8b, v3.8b, v4.8b
+; CHECK-NEXT:    and v2.8b, v0.8b, v2.8b
+; CHECK-NEXT:    and v1.8b, v1.8b, v4.8b
+; CHECK-NEXT:    neg v3.2s, v3.2s
+; CHECK-NEXT:    ushl v2.2s, v2.2s, v3.2s
+; CHECK-NEXT:    ushl v0.2s, v0.2s, v1.2s
+; CHECK-NEXT:    orr v0.8b, v0.8b, v2.8b
+; CHECK-NEXT:    ret
+  %1 = call <2 x i16> @llvm.fshl.v2i16(<2 x i16> %vec2_16, <2 x i16> %vec2_16, <2 x i16> %shift)
+  ret <2 x i16> %1
+}