1 //===-- BPFISelDAGToDAG.cpp - A dag to dag inst selector for BPF ----------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines a DAG pattern matching instruction selector for BPF, 11 // converting from a legalized dag to a BPF dag. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "BPF.h" 16 #include "BPFRegisterInfo.h" 17 #include "BPFSubtarget.h" 18 #include "BPFTargetMachine.h" 19 #include "llvm/CodeGen/MachineConstantPool.h" 20 #include "llvm/CodeGen/MachineFrameInfo.h" 21 #include "llvm/CodeGen/MachineFunction.h" 22 #include "llvm/CodeGen/MachineInstrBuilder.h" 23 #include "llvm/CodeGen/MachineRegisterInfo.h" 24 #include "llvm/CodeGen/SelectionDAGISel.h" 25 #include "llvm/IR/IntrinsicInst.h" 26 #include "llvm/Support/Debug.h" 27 #include "llvm/Support/ErrorHandling.h" 28 #include "llvm/Support/raw_ostream.h" 29 #include "llvm/Target/TargetMachine.h" 30 using namespace llvm; 31 32 #define DEBUG_TYPE "bpf-isel" 33 34 // Instruction Selector Implementation 35 namespace { 36 37 class BPFDAGToDAGISel : public SelectionDAGISel { 38 public: 39 explicit BPFDAGToDAGISel(BPFTargetMachine &TM) : SelectionDAGISel(TM) {} 40 41 const char *getPassName() const override { 42 return "BPF DAG->DAG Pattern Instruction Selection"; 43 } 44 45 private: 46 // Include the pieces autogenerated from the target description. 47 #include "BPFGenDAGISel.inc" 48 49 void Select(SDNode *N) override; 50 51 // Complex Pattern for address selection. 52 bool SelectAddr(SDValue Addr, SDValue &Base, SDValue &Offset); 53 bool SelectFIAddr(SDValue Addr, SDValue &Base, SDValue &Offset); 54 }; 55 } 56 57 // ComplexPattern used on BPF Load/Store instructions 58 bool BPFDAGToDAGISel::SelectAddr(SDValue Addr, SDValue &Base, SDValue &Offset) { 59 // if Address is FI, get the TargetFrameIndex. 60 SDLoc DL(Addr); 61 if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) { 62 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64); 63 Offset = CurDAG->getTargetConstant(0, DL, MVT::i64); 64 return true; 65 } 66 67 if (Addr.getOpcode() == ISD::TargetExternalSymbol || 68 Addr.getOpcode() == ISD::TargetGlobalAddress) 69 return false; 70 71 // Addresses of the form Addr+const or Addr|const 72 if (CurDAG->isBaseWithConstantOffset(Addr)) { 73 ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1)); 74 if (isInt<32>(CN->getSExtValue())) { 75 76 // If the first operand is a FI, get the TargetFI Node 77 if (FrameIndexSDNode *FIN = 78 dyn_cast<FrameIndexSDNode>(Addr.getOperand(0))) 79 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64); 80 else 81 Base = Addr.getOperand(0); 82 83 Offset = CurDAG->getTargetConstant(CN->getSExtValue(), DL, MVT::i64); 84 return true; 85 } 86 } 87 88 Base = Addr; 89 Offset = CurDAG->getTargetConstant(0, DL, MVT::i64); 90 return true; 91 } 92 93 // ComplexPattern used on BPF FI instruction 94 bool BPFDAGToDAGISel::SelectFIAddr(SDValue Addr, SDValue &Base, SDValue &Offset) { 95 SDLoc DL(Addr); 96 97 if (!CurDAG->isBaseWithConstantOffset(Addr)) 98 return false; 99 100 // Addresses of the form Addr+const or Addr|const 101 ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1)); 102 if (isInt<32>(CN->getSExtValue())) { 103 104 // If the first operand is a FI, get the TargetFI Node 105 if (FrameIndexSDNode *FIN = 106 dyn_cast<FrameIndexSDNode>(Addr.getOperand(0))) 107 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64); 108 else 109 return false; 110 111 Offset = CurDAG->getTargetConstant(CN->getSExtValue(), DL, MVT::i64); 112 return true; 113 } 114 115 return false; 116 } 117 118 void BPFDAGToDAGISel::Select(SDNode *Node) { 119 unsigned Opcode = Node->getOpcode(); 120 121 // Dump information about the Node being selected 122 DEBUG(dbgs() << "Selecting: "; Node->dump(CurDAG); dbgs() << '\n'); 123 124 // If we have a custom node, we already have selected! 125 if (Node->isMachineOpcode()) { 126 DEBUG(dbgs() << "== "; Node->dump(CurDAG); dbgs() << '\n'); 127 return; 128 } 129 130 // tablegen selection should be handled here. 131 switch (Opcode) { 132 default: break; 133 case ISD::SDIV: { 134 DebugLoc Empty; 135 const DebugLoc &DL = Node->getDebugLoc(); 136 if (DL != Empty) 137 errs() << "Error at line " << DL.getLine() << ": "; 138 else 139 errs() << "Error: "; 140 errs() << "Unsupport signed division for DAG: "; 141 Node->dump(CurDAG); 142 errs() << "Please convert to unsigned div/mod.\n"; 143 break; 144 } 145 case ISD::INTRINSIC_W_CHAIN: { 146 unsigned IntNo = cast<ConstantSDNode>(Node->getOperand(1))->getZExtValue(); 147 switch (IntNo) { 148 case Intrinsic::bpf_load_byte: 149 case Intrinsic::bpf_load_half: 150 case Intrinsic::bpf_load_word: { 151 SDLoc DL(Node); 152 SDValue Chain = Node->getOperand(0); 153 SDValue N1 = Node->getOperand(1); 154 SDValue Skb = Node->getOperand(2); 155 SDValue N3 = Node->getOperand(3); 156 157 SDValue R6Reg = CurDAG->getRegister(BPF::R6, MVT::i64); 158 Chain = CurDAG->getCopyToReg(Chain, DL, R6Reg, Skb, SDValue()); 159 Node = CurDAG->UpdateNodeOperands(Node, Chain, N1, R6Reg, N3); 160 break; 161 } 162 } 163 break; 164 } 165 166 case ISD::FrameIndex: { 167 int FI = cast<FrameIndexSDNode>(Node)->getIndex(); 168 EVT VT = Node->getValueType(0); 169 SDValue TFI = CurDAG->getTargetFrameIndex(FI, VT); 170 unsigned Opc = BPF::MOV_rr; 171 if (Node->hasOneUse()) { 172 CurDAG->SelectNodeTo(Node, Opc, VT, TFI); 173 return; 174 } 175 ReplaceNode(Node, CurDAG->getMachineNode(Opc, SDLoc(Node), VT, TFI)); 176 return; 177 } 178 } 179 180 // Select the default instruction 181 SelectCode(Node); 182 } 183 184 FunctionPass *llvm::createBPFISelDag(BPFTargetMachine &TM) { 185 return new BPFDAGToDAGISel(TM); 186 } 187
