[ARM] Add ARMISD::VLD1DUP to match vld1_dup more consistently.

Currently, there are substantial problems forming vld1_dup even if the
VDUP survives legalization. The lack of an actual node
leads to terrible results: not only can we not form post-increment vld1_dup
instructions, but we form scalar pre-increment and post-increment
loads which force the loaded value into a GPR. This patch fixes that
by combining the vdup+load into an ARMISD node before DAGCombine
messes it up.

Also includes a crash fix for vld2_dup (see testcase @vld2dupi8_postinc_variable).

Differential Revision: https://reviews.llvm.org/D27694

llvm-svn: 289703

1 files changed, 58 insertions, 16 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
index e35ec3f8a3a..e257f2faf83 100644
--- a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -222,10 +222,11 @@ private:
                        const uint16_t *QOpcodes);
 
   /// SelectVLDDup - Select NEON load-duplicate intrinsics.  NumVecs
-  /// should be 2, 3 or 4.  The opcode array specifies the instructions used
+  /// should be 1, 2, 3 or 4.  The opcode array specifies the instructions used
   /// for loading D registers.  (Q registers are not supported.)
   void SelectVLDDup(SDNode *N, bool isUpdating, unsigned NumVecs,
-                    const uint16_t *Opcodes);
+                    const uint16_t *DOpcodes,
+                    const uint16_t *QOpcodes = nullptr);
 
   /// SelectVTBL - Select NEON VTBL and VTBX intrinsics.  NumVecs should be 2,
   /// 3 or 4.  These are custom-selected so that a REG_SEQUENCE can be
@@ -1761,6 +1762,12 @@ static bool isVLDfixed(unsigned Opc)
   case ARM::VLD1q16wb_fixed : return true;
   case ARM::VLD1q32wb_fixed : return true;
   case ARM::VLD1q64wb_fixed : return true;
+  case ARM::VLD1DUPd8wb_fixed : return true;
+  case ARM::VLD1DUPd16wb_fixed : return true;
+  case ARM::VLD1DUPd32wb_fixed : return true;
+  case ARM::VLD1DUPq8wb_fixed : return true;
+  case ARM::VLD1DUPq16wb_fixed : return true;
+  case ARM::VLD1DUPq32wb_fixed : return true;
   case ARM::VLD2d8wb_fixed : return true;
   case ARM::VLD2d16wb_fixed : return true;
   case ARM::VLD2d32wb_fixed : return true;
@@ -1815,6 +1822,12 @@ static unsigned getVLDSTRegisterUpdateOpcode(unsigned Opc) {
   case ARM::VLD1d64Qwb_fixed: return ARM::VLD1d64Qwb_register;
   case ARM::VLD1d64TPseudoWB_fixed: return ARM::VLD1d64TPseudoWB_register;
   case ARM::VLD1d64QPseudoWB_fixed: return ARM::VLD1d64QPseudoWB_register;
+  case ARM::VLD1DUPd8wb_fixed : return ARM::VLD1DUPd8wb_register;
+  case ARM::VLD1DUPd16wb_fixed : return ARM::VLD1DUPd16wb_register;
+  case ARM::VLD1DUPd32wb_fixed : return ARM::VLD1DUPd32wb_register;
+  case ARM::VLD1DUPq8wb_fixed : return ARM::VLD1DUPq8wb_register;
+  case ARM::VLD1DUPq16wb_fixed : return ARM::VLD1DUPq16wb_register;
+  case ARM::VLD1DUPq32wb_fixed : return ARM::VLD1DUPq32wb_register;
 
   case ARM::VST1d8wb_fixed: return ARM::VST1d8wb_register;
   case ARM::VST1d16wb_fixed: return ARM::VST1d16wb_register;
@@ -2255,8 +2268,9 @@ void ARMDAGToDAGISel::SelectVLDSTLane(SDNode *N, bool IsLoad, bool isUpdating,
 }
 
 void ARMDAGToDAGISel::SelectVLDDup(SDNode *N, bool isUpdating, unsigned NumVecs,
-                                   const uint16_t *Opcodes) {
-  assert(NumVecs >=2 && NumVecs <= 4 && "VLDDup NumVecs out-of-range");
+                                   const uint16_t *DOpcodes,
+                                   const uint16_t *QOpcodes) {
+  assert(NumVecs >= 1 && NumVecs <= 4 && "VLDDup NumVecs out-of-range");
   SDLoc dl(N);
 
   SDValue MemAddr, Align;
@@ -2284,19 +2298,21 @@ void ARMDAGToDAGISel::SelectVLDDup(SDNode *N, bool isUpdating, unsigned NumVecs,
   }
   Align = CurDAG->getTargetConstant(Alignment, dl, MVT::i32);
 
-  unsigned OpcodeIndex;
+  unsigned Opc;
   switch (VT.getSimpleVT().SimpleTy) {
   default: llvm_unreachable("unhandled vld-dup type");
-  case MVT::v8i8:  OpcodeIndex = 0; break;
-  case MVT::v4i16: OpcodeIndex = 1; break;
+  case MVT::v8i8:  Opc = DOpcodes[0]; break;
+  case MVT::v16i8: Opc = QOpcodes[0]; break;
+  case MVT::v4i16: Opc = DOpcodes[1]; break;
+  case MVT::v8i16: Opc = QOpcodes[1]; break;
   case MVT::v2f32:
-  case MVT::v2i32: OpcodeIndex = 2; break;
+  case MVT::v2i32: Opc = DOpcodes[2]; break;
+  case MVT::v4f32:
+  case MVT::v4i32: Opc = QOpcodes[2]; break;
   }
 
   SDValue Pred = getAL(CurDAG, dl);
   SDValue Reg0 = CurDAG->getRegister(0, MVT::i32);
-  SDValue SuperReg;
-  unsigned Opc = Opcodes[OpcodeIndex];
   SmallVector<SDValue, 6> Ops;
   Ops.push_back(MemAddr);
   Ops.push_back(Align);
@@ -2304,6 +2320,8 @@ void ARMDAGToDAGISel::SelectVLDDup(SDNode *N, bool isUpdating, unsigned NumVecs,
     // fixed-stride update instructions don't have an explicit writeback
     // operand. It's implicit in the opcode itself.
     SDValue Inc = N->getOperand(2);
+    if (NumVecs <= 2 && !isa<ConstantSDNode>(Inc.getNode()))
+      Opc = getVLDSTRegisterUpdateOpcode(Opc);
     if (!isa<ConstantSDNode>(Inc.getNode()))
       Ops.push_back(Inc);
     // FIXME: VLD3 and VLD4 haven't been updated to that form yet.
@@ -2322,14 +2340,18 @@ void ARMDAGToDAGISel::SelectVLDDup(SDNode *N, bool isUpdating, unsigned NumVecs,
   ResTys.push_back(MVT::Other);
   SDNode *VLdDup = CurDAG->getMachineNode(Opc, dl, ResTys, Ops);
   cast<MachineSDNode>(VLdDup)->setMemRefs(MemOp, MemOp + 1);
-  SuperReg = SDValue(VLdDup, 0);
 
   // Extract the subregisters.
-  static_assert(ARM::dsub_7 == ARM::dsub_0 + 7, "Unexpected subreg numbering");
-  unsigned SubIdx = ARM::dsub_0;
-  for (unsigned Vec = 0; Vec < NumVecs; ++Vec)
-    ReplaceUses(SDValue(N, Vec),
-                CurDAG->getTargetExtractSubreg(SubIdx+Vec, dl, VT, SuperReg));
+  if (NumVecs == 1) {
+    ReplaceUses(SDValue(N, 0), SDValue(VLdDup, 0));
+  } else {
+    SDValue SuperReg = SDValue(VLdDup, 0);
+    static_assert(ARM::dsub_7 == ARM::dsub_0 + 7, "Unexpected subreg numbering");
+    unsigned SubIdx = ARM::dsub_0;
+    for (unsigned Vec = 0; Vec < NumVecs; ++Vec)
+      ReplaceUses(SDValue(N, Vec),
+                  CurDAG->getTargetExtractSubreg(SubIdx+Vec, dl, VT, SuperReg));
+  }
   ReplaceUses(SDValue(N, NumVecs), SDValue(VLdDup, 1));
   if (isUpdating)
     ReplaceUses(SDValue(N, NumVecs + 1), SDValue(VLdDup, 2));
@@ -3269,6 +3291,15 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
     return;
   }
 
+  case ARMISD::VLD1DUP: {
+    static const uint16_t DOpcodes[] = { ARM::VLD1DUPd8, ARM::VLD1DUPd16,
+                                         ARM::VLD1DUPd32 };
+    static const uint16_t QOpcodes[] = { ARM::VLD1DUPq8, ARM::VLD1DUPq16,
+                                         ARM::VLD1DUPq32 };
+    SelectVLDDup(N, false, 1, DOpcodes, QOpcodes);
+    return;
+  }
+
   case ARMISD::VLD2DUP: {
     static const uint16_t Opcodes[] = { ARM::VLD2DUPd8, ARM::VLD2DUPd16,
                                         ARM::VLD2DUPd32 };
@@ -3292,6 +3323,17 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
     return;
   }
 
+  case ARMISD::VLD1DUP_UPD: {
+    static const uint16_t DOpcodes[] = { ARM::VLD1DUPd8wb_fixed,
+                                         ARM::VLD1DUPd16wb_fixed,
+                                         ARM::VLD1DUPd32wb_fixed };
+    static const uint16_t QOpcodes[] = { ARM::VLD1DUPq8wb_fixed,
+                                         ARM::VLD1DUPq16wb_fixed,
+                                         ARM::VLD1DUPq32wb_fixed };
+    SelectVLDDup(N, true, 1, DOpcodes, QOpcodes);
+    return;
+  }
+
   case ARMISD::VLD2DUP_UPD: {
     static const uint16_t Opcodes[] = { ARM::VLD2DUPd8wb_fixed,
                                         ARM::VLD2DUPd16wb_fixed,