1 files changed, 415 insertions, 0 deletions
diff --git a/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp b/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
new file mode 100644
index 0000000..46b8221
--- /dev/null
+++ b/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
@@ -0,0 +1,415 @@
+//===-- AArch64ISelDAGToDAG.cpp - A dag to dag inst selector for AArch64 --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines an instruction selector for the AArch64 target.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "aarch64-isel"
+#include "AArch64.h"
+#include "AArch64InstrInfo.h"
+#include "AArch64Subtarget.h"
+#include "AArch64TargetMachine.h"
+#include "Utils/AArch64BaseInfo.h"
+#include "llvm/ADT/APSInt.h"
+#include "llvm/CodeGen/SelectionDAGISel.h"
+#include "llvm/IR/GlobalValue.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+//===--------------------------------------------------------------------===//
+/// AArch64 specific code to select AArch64 machine instructions for
+/// SelectionDAG operations.
+///
+namespace {
+
+class AArch64DAGToDAGISel : public SelectionDAGISel {
+  AArch64TargetMachine &TM;
+  const AArch64InstrInfo *TII;
+
+  /// Keep a pointer to the AArch64Subtarget around so that we can
+  /// make the right decision when generating code for different targets.
+  const AArch64Subtarget *Subtarget;
+
+public:
+  explicit AArch64DAGToDAGISel(AArch64TargetMachine &tm,
+                               CodeGenOpt::Level OptLevel)
+    : SelectionDAGISel(tm, OptLevel), TM(tm),
+      TII(static_cast<const AArch64InstrInfo*>(TM.getInstrInfo())),
+      Subtarget(&TM.getSubtarget<AArch64Subtarget>()) {
+  }
+
+  virtual const char *getPassName() const {
+    return "AArch64 Instruction Selection";
+  }
+
+  // Include the pieces autogenerated from the target description.
+#include "AArch64GenDAGISel.inc"
+
+  template<unsigned MemSize>
+  bool SelectOffsetUImm12(SDValue N, SDValue &UImm12) {
+    const ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N);
+    if (!CN || CN->getZExtValue() % MemSize != 0
+        || CN->getZExtValue() / MemSize > 0xfff)
+      return false;
+
+    UImm12 =  CurDAG->getTargetConstant(CN->getZExtValue() / MemSize, MVT::i64);
+    return true;
+  }
+
+  template<unsigned RegWidth>
+  bool SelectCVTFixedPosOperand(SDValue N, SDValue &FixedPos) {
+    return SelectCVTFixedPosOperand(N, FixedPos, RegWidth);
+  }
+
+  bool SelectFPZeroOperand(SDValue N, SDValue &Dummy);
+
+  bool SelectCVTFixedPosOperand(SDValue N, SDValue &FixedPos,
+                                unsigned RegWidth);
+
+  bool SelectInlineAsmMemoryOperand(const SDValue &Op,
+                                    char ConstraintCode,
+                                    std::vector<SDValue> &OutOps);
+
+  bool SelectLogicalImm(SDValue N, SDValue &Imm);
+
+  template<unsigned RegWidth>
+  bool SelectTSTBOperand(SDValue N, SDValue &FixedPos) {
+    return SelectTSTBOperand(N, FixedPos, RegWidth);
+  }
+
+  bool SelectTSTBOperand(SDValue N, SDValue &FixedPos, unsigned RegWidth);
+
+  SDNode *TrySelectToMoveImm(SDNode *N);
+  SDNode *LowerToFPLitPool(SDNode *Node);
+  SDNode *SelectToLitPool(SDNode *N);
+
+  SDNode* Select(SDNode*);
+private:
+};
+}
+
+bool
+AArch64DAGToDAGISel::SelectCVTFixedPosOperand(SDValue N, SDValue &FixedPos,
+                                              unsigned RegWidth) {
+  const ConstantFPSDNode *CN = dyn_cast<ConstantFPSDNode>(N);
+  if (!CN) return false;
+
+  // An FCVT[SU] instruction performs: convertToInt(Val * 2^fbits) where fbits
+  // is between 1 and 32 for a destination w-register, or 1 and 64 for an
+  // x-register.
+  //
+  // By this stage, we've detected (fp_to_[su]int (fmul Val, THIS_NODE)) so we
+  // want THIS_NODE to be 2^fbits. This is much easier to deal with using
+  // integers.
+  bool IsExact;
+
+  // fbits is between 1 and 64 in the worst-case, which means the fmul
+  // could have 2^64 as an actual operand. Need 65 bits of precision.
+  APSInt IntVal(65, true);
+  CN->getValueAPF().convertToInteger(IntVal, APFloat::rmTowardZero, &IsExact);
+
+  // N.b. isPowerOf2 also checks for > 0.
+  if (!IsExact || !IntVal.isPowerOf2()) return false;
+  unsigned FBits = IntVal.logBase2();
+
+  // Checks above should have guaranteed that we haven't lost information in
+  // finding FBits, but it must still be in range.
+  if (FBits == 0 || FBits > RegWidth) return false;
+
+  FixedPos = CurDAG->getTargetConstant(64 - FBits, MVT::i32);
+  return true;
+}
+
+bool
+AArch64DAGToDAGISel::SelectInlineAsmMemoryOperand(const SDValue &Op,
+                                                 char ConstraintCode,
+                                                 std::vector<SDValue> &OutOps) {
+  switch (ConstraintCode) {
+  default: llvm_unreachable("Unrecognised AArch64 memory constraint");
+  case 'm':
+    // FIXME: more freedom is actually permitted for 'm'. We can go
+    // hunting for a base and an offset if we want. Of course, since
+    // we don't really know how the operand is going to be used we're
+    // probably restricted to the load/store pair's simm7 as an offset
+    // range anyway.
+  case 'Q':
+    OutOps.push_back(Op);
+  }
+
+  return false;
+}
+
+bool
+AArch64DAGToDAGISel::SelectFPZeroOperand(SDValue N, SDValue &Dummy) {
+  ConstantFPSDNode *Imm = dyn_cast<ConstantFPSDNode>(N);
+  if (!Imm || !Imm->getValueAPF().isPosZero())
+    return false;
+
+  // Doesn't actually carry any information, but keeps TableGen quiet.
+  Dummy = CurDAG->getTargetConstant(0, MVT::i32);
+  return true;
+}
+
+bool AArch64DAGToDAGISel::SelectLogicalImm(SDValue N, SDValue &Imm) {
+  uint32_t Bits;
+  uint32_t RegWidth = N.getValueType().getSizeInBits();
+
+  ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N);
+  if (!CN) return false;
+
+  if (!A64Imms::isLogicalImm(RegWidth, CN->getZExtValue(), Bits))
+    return false;
+
+  Imm = CurDAG->getTargetConstant(Bits, MVT::i32);
+  return true;
+}
+
+SDNode *AArch64DAGToDAGISel::TrySelectToMoveImm(SDNode *Node) {
+  SDNode *ResNode;
+  DebugLoc dl = Node->getDebugLoc();
+  EVT DestType = Node->getValueType(0);
+  unsigned DestWidth = DestType.getSizeInBits();
+
+  unsigned MOVOpcode;
+  EVT MOVType;
+  int UImm16, Shift;
+  uint32_t LogicalBits;
+
+  uint64_t BitPat = cast<ConstantSDNode>(Node)->getZExtValue();
+  if (A64Imms::isMOVZImm(DestWidth, BitPat, UImm16, Shift)) {
+    MOVType = DestType;
+    MOVOpcode = DestWidth == 64 ? AArch64::MOVZxii : AArch64::MOVZwii;
+  } else if (A64Imms::isMOVNImm(DestWidth, BitPat, UImm16, Shift)) {
+    MOVType = DestType;
+    MOVOpcode = DestWidth == 64 ? AArch64::MOVNxii : AArch64::MOVNwii;
+  } else if (DestWidth == 64 && A64Imms::isMOVNImm(32, BitPat, UImm16, Shift)) {
+    // To get something like 0x0000_0000_ffff_1234 into a 64-bit register we can
+    // use a 32-bit instruction: "movn w0, 0xedbc".
+    MOVType = MVT::i32;
+    MOVOpcode = AArch64::MOVNwii;
+  } else if (A64Imms::isLogicalImm(DestWidth, BitPat, LogicalBits))  {
+    MOVOpcode = DestWidth == 64 ? AArch64::ORRxxi : AArch64::ORRwwi;
+    uint16_t ZR = DestWidth == 64 ? AArch64::XZR : AArch64::WZR;
+
+    return CurDAG->getMachineNode(MOVOpcode, dl, DestType,
+                              CurDAG->getRegister(ZR, DestType),
+                              CurDAG->getTargetConstant(LogicalBits, MVT::i32));
+  } else {
+    // Can't handle it in one instruction. There's scope for permitting two (or
+    // more) instructions, but that'll need more thought.
+    return NULL;
+  }
+
+  ResNode = CurDAG->getMachineNode(MOVOpcode, dl, MOVType,
+                                   CurDAG->getTargetConstant(UImm16, MVT::i32),
+                                   CurDAG->getTargetConstant(Shift, MVT::i32));
+
+  if (MOVType != DestType) {
+    ResNode = CurDAG->getMachineNode(TargetOpcode::SUBREG_TO_REG, dl,
+                          MVT::i64, MVT::i32, MVT::Other,
+                          CurDAG->getTargetConstant(0, MVT::i64),
+                          SDValue(ResNode, 0),
+                          CurDAG->getTargetConstant(AArch64::sub_32, MVT::i32));
+  }
+
+  return ResNode;
+}
+
+SDNode *AArch64DAGToDAGISel::SelectToLitPool(SDNode *Node) {
+  DebugLoc DL = Node->getDebugLoc();
+  uint64_t UnsignedVal = cast<ConstantSDNode>(Node)->getZExtValue();
+  int64_t SignedVal = cast<ConstantSDNode>(Node)->getSExtValue();
+  EVT DestType = Node->getValueType(0);
+  EVT PtrVT = TLI.getPointerTy();
+
+  // Since we may end up loading a 64-bit constant from a 32-bit entry the
+  // constant in the pool may have a different type to the eventual node.
+  ISD::LoadExtType Extension;
+  EVT MemType;
+
+  assert((DestType == MVT::i64 || DestType == MVT::i32)
+         && "Only expect integer constants at the moment");
+
+  if (DestType == MVT::i32) {
+    Extension = ISD::NON_EXTLOAD;
+    MemType = MVT::i32;
+  } else if (UnsignedVal <= UINT32_MAX) {
+    Extension = ISD::ZEXTLOAD;
+    MemType = MVT::i32;
+  } else if (SignedVal >= INT32_MIN && SignedVal <= INT32_MAX) {
+    Extension = ISD::SEXTLOAD;
+    MemType = MVT::i32;
+  } else {
+    Extension = ISD::NON_EXTLOAD;
+    MemType = MVT::i64;
+  }
+
+  Constant *CV = ConstantInt::get(Type::getIntNTy(*CurDAG->getContext(),
+                                                  MemType.getSizeInBits()),
+                                  UnsignedVal);
+  SDValue PoolAddr;
+  unsigned Alignment = TLI.getDataLayout()->getABITypeAlignment(CV->getType());
+  PoolAddr = CurDAG->getNode(AArch64ISD::WrapperSmall, DL, PtrVT,
+                             CurDAG->getTargetConstantPool(CV, PtrVT, 0, 0,
+                                                         AArch64II::MO_NO_FLAG),
+                             CurDAG->getTargetConstantPool(CV, PtrVT, 0, 0,
+                                                           AArch64II::MO_LO12),
+                             CurDAG->getConstant(Alignment, MVT::i32));
+
+  return CurDAG->getExtLoad(Extension, DL, DestType, CurDAG->getEntryNode(),
+                            PoolAddr,
+                            MachinePointerInfo::getConstantPool(), MemType,
+                            /* isVolatile = */ false,
+                            /* isNonTemporal = */ false,
+                            Alignment).getNode();
+}
+
+SDNode *AArch64DAGToDAGISel::LowerToFPLitPool(SDNode *Node) {
+  DebugLoc DL = Node->getDebugLoc();
+  const ConstantFP *FV = cast<ConstantFPSDNode>(Node)->getConstantFPValue();
+  EVT PtrVT = TLI.getPointerTy();
+  EVT DestType = Node->getValueType(0);
+
+  unsigned Alignment = TLI.getDataLayout()->getABITypeAlignment(FV->getType());
+  SDValue PoolAddr;
+
+  assert(TM.getCodeModel() == CodeModel::Small &&
+         "Only small code model supported");
+  PoolAddr = CurDAG->getNode(AArch64ISD::WrapperSmall, DL, PtrVT,
+                             CurDAG->getTargetConstantPool(FV, PtrVT, 0, 0,
+                                                         AArch64II::MO_NO_FLAG),
+                             CurDAG->getTargetConstantPool(FV, PtrVT, 0, 0,
+                                                           AArch64II::MO_LO12),
+                             CurDAG->getConstant(Alignment, MVT::i32));
+
+  return CurDAG->getLoad(DestType, DL, CurDAG->getEntryNode(), PoolAddr,
+                         MachinePointerInfo::getConstantPool(),
+                         /* isVolatile = */ false,
+                         /* isNonTemporal = */ false,
+                         /* isInvariant = */ true,
+                         Alignment).getNode();
+}
+
+bool
+AArch64DAGToDAGISel::SelectTSTBOperand(SDValue N, SDValue &FixedPos,
+                                       unsigned RegWidth) {
+  const ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N);
+  if (!CN) return false;
+
+  uint64_t Val = CN->getZExtValue();
+
+  if (!isPowerOf2_64(Val)) return false;
+
+  unsigned TestedBit = Log2_64(Val);
+  // Checks above should have guaranteed that we haven't lost information in
+  // finding TestedBit, but it must still be in range.
+  if (TestedBit >= RegWidth) return false;
+
+  FixedPos = CurDAG->getTargetConstant(TestedBit, MVT::i64);
+  return true;
+}
+
+SDNode *AArch64DAGToDAGISel::Select(SDNode *Node) {
+  // Dump information about the Node being selected
+  DEBUG(dbgs() << "Selecting: "; Node->dump(CurDAG); dbgs() << "\n");
+
+  if (Node->isMachineOpcode()) {
+    DEBUG(dbgs() << "== "; Node->dump(CurDAG); dbgs() << "\n");
+    return NULL;
+  }
+
+  switch (Node->getOpcode()) {
+  case ISD::FrameIndex: {
+    int FI = cast<FrameIndexSDNode>(Node)->getIndex();
+    EVT PtrTy = TLI.getPointerTy();
+    SDValue TFI = CurDAG->getTargetFrameIndex(FI, PtrTy);
+    return CurDAG->SelectNodeTo(Node, AArch64::ADDxxi_lsl0_s, PtrTy,
+                                TFI, CurDAG->getTargetConstant(0, PtrTy));
+  }
+  case ISD::ConstantPool: {
+    // Constant pools are fine, just create a Target entry.
+    ConstantPoolSDNode *CN = cast<ConstantPoolSDNode>(Node);
+    const Constant *C = CN->getConstVal();
+    SDValue CP = CurDAG->getTargetConstantPool(C, CN->getValueType(0));
+
+    ReplaceUses(SDValue(Node, 0), CP);
+    return NULL;
+  }
+  case ISD::Constant: {
+    SDNode *ResNode = 0;
+    if (cast<ConstantSDNode>(Node)->getZExtValue() == 0) {
+      // XZR and WZR are probably even better than an actual move: most of the
+      // time they can be folded into another instruction with *no* cost.
+
+      EVT Ty = Node->getValueType(0);
+      assert((Ty == MVT::i32 || Ty == MVT::i64) && "unexpected type");
+      uint16_t Register = Ty == MVT::i32 ? AArch64::WZR : AArch64::XZR;
+      ResNode = CurDAG->getCopyFromReg(CurDAG->getEntryNode(),
+                                       Node->getDebugLoc(),
+                                       Register, Ty).getNode();
+    }
+
+    // Next best option is a move-immediate, see if we can do that.
+    if (!ResNode) {
+      ResNode = TrySelectToMoveImm(Node);
+    }
+
+    if (ResNode)
+      return ResNode;
+
+    // If even that fails we fall back to a lit-pool entry at the moment. Future
+    // tuning may change this to a sequence of MOVZ/MOVN/MOVK instructions.
+    ResNode = SelectToLitPool(Node);
+    assert(ResNode && "We need *some* way to materialise a constant");
+
+    // We want to continue selection at this point since the litpool access
+    // generated used generic nodes for simplicity.
+    ReplaceUses(SDValue(Node, 0), SDValue(ResNode, 0));
+    Node = ResNode;
+    break;
+  }
+  case ISD::ConstantFP: {
+    if (A64Imms::isFPImm(cast<ConstantFPSDNode>(Node)->getValueAPF())) {
+      // FMOV will take care of it from TableGen
+      break;
+    }
+
+    SDNode *ResNode = LowerToFPLitPool(Node);
+    ReplaceUses(SDValue(Node, 0), SDValue(ResNode, 0));
+
+    // We want to continue selection at this point since the litpool access
+    // generated used generic nodes for simplicity.
+    Node = ResNode;
+    break;
+  }
+  default:
+    break; // Let generic code handle it
+  }
+
+  SDNode *ResNode = SelectCode(Node);
+
+  DEBUG(dbgs() << "=> ";
+        if (ResNode == NULL || ResNode == Node)
+          Node->dump(CurDAG);
+        else
+          ResNode->dump(CurDAG);
+        dbgs() << "\n");
+
+  return ResNode;
+}
+
+/// This pass converts a legalized DAG into a AArch64-specific DAG, ready for
+/// instruction scheduling.
+FunctionPass *llvm::createAArch64ISelDAG(AArch64TargetMachine &TM,
+                                         CodeGenOpt::Level OptLevel) {
+  return new AArch64DAGToDAGISel(TM, OptLevel);
+}