1//===-- BPFMCCodeEmitter.cpp - Convert BPF code to machine code -----------===// 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 implements the BPFMCCodeEmitter class. 11// 12//===----------------------------------------------------------------------===// 13 14#include "MCTargetDesc/BPFMCTargetDesc.h" 15#include "llvm/MC/MCCodeEmitter.h" 16#include "llvm/MC/MCFixup.h" 17#include "llvm/MC/MCInst.h" 18#include "llvm/MC/MCInstrInfo.h" 19#include "llvm/MC/MCRegisterInfo.h" 20#include "llvm/MC/MCSubtargetInfo.h" 21#include "llvm/MC/MCSymbol.h" 22#include "llvm/ADT/Statistic.h" 23#include "llvm/Support/raw_ostream.h" 24using namespace llvm; 25 26#define DEBUG_TYPE "mccodeemitter" 27 28namespace { 29class BPFMCCodeEmitter : public MCCodeEmitter { 30 BPFMCCodeEmitter(const BPFMCCodeEmitter &) = delete; 31 void operator=(const BPFMCCodeEmitter &) = delete; 32 const MCRegisterInfo &MRI; 33 34public: 35 BPFMCCodeEmitter(const MCRegisterInfo &mri) : MRI(mri) {} 36 37 ~BPFMCCodeEmitter() {} 38 39 // getBinaryCodeForInstr - TableGen'erated function for getting the 40 // binary encoding for an instruction. 41 uint64_t getBinaryCodeForInstr(const MCInst &MI, 42 SmallVectorImpl<MCFixup> &Fixups, 43 const MCSubtargetInfo &STI) const; 44 45 // getMachineOpValue - Return binary encoding of operand. If the machin 46 // operand requires relocation, record the relocation and return zero. 47 unsigned getMachineOpValue(const MCInst &MI, const MCOperand &MO, 48 SmallVectorImpl<MCFixup> &Fixups, 49 const MCSubtargetInfo &STI) const; 50 51 uint64_t getMemoryOpValue(const MCInst &MI, unsigned Op, 52 SmallVectorImpl<MCFixup> &Fixups, 53 const MCSubtargetInfo &STI) const; 54 55 void EncodeInstruction(const MCInst &MI, raw_ostream &OS, 56 SmallVectorImpl<MCFixup> &Fixups, 57 const MCSubtargetInfo &STI) const override; 58}; 59} 60 61MCCodeEmitter *llvm::createBPFMCCodeEmitter(const MCInstrInfo &MCII, 62 const MCRegisterInfo &MRI, 63 MCContext &Ctx) { 64 return new BPFMCCodeEmitter(MRI); 65} 66 67unsigned BPFMCCodeEmitter::getMachineOpValue(const MCInst &MI, 68 const MCOperand &MO, 69 SmallVectorImpl<MCFixup> &Fixups, 70 const MCSubtargetInfo &STI) const { 71 if (MO.isReg()) 72 return MRI.getEncodingValue(MO.getReg()); 73 if (MO.isImm()) 74 return static_cast<unsigned>(MO.getImm()); 75 76 assert(MO.isExpr()); 77 78 const MCExpr *Expr = MO.getExpr(); 79 80 assert(Expr->getKind() == MCExpr::SymbolRef); 81 82 if (MI.getOpcode() == BPF::JAL) 83 // func call name 84 Fixups.push_back(MCFixup::Create(0, Expr, FK_SecRel_4)); 85 else if (MI.getOpcode() == BPF::LD_imm64) 86 Fixups.push_back(MCFixup::Create(0, Expr, FK_SecRel_8)); 87 else 88 // bb label 89 Fixups.push_back(MCFixup::Create(0, Expr, FK_PCRel_2)); 90 91 return 0; 92} 93 94// Emit one byte through output stream 95void EmitByte(unsigned char C, unsigned &CurByte, raw_ostream &OS) { 96 OS << (char)C; 97 ++CurByte; 98} 99 100// Emit a series of bytes (little endian) 101void EmitLEConstant(uint64_t Val, unsigned Size, unsigned &CurByte, 102 raw_ostream &OS) { 103 assert(Size <= 8 && "size too big in emit constant"); 104 105 for (unsigned i = 0; i != Size; ++i) { 106 EmitByte(Val & 255, CurByte, OS); 107 Val >>= 8; 108 } 109} 110 111// Emit a series of bytes (big endian) 112void EmitBEConstant(uint64_t Val, unsigned Size, unsigned &CurByte, 113 raw_ostream &OS) { 114 assert(Size <= 8 && "size too big in emit constant"); 115 116 for (int i = (Size - 1) * 8; i >= 0; i -= 8) 117 EmitByte((Val >> i) & 255, CurByte, OS); 118} 119 120void BPFMCCodeEmitter::EncodeInstruction(const MCInst &MI, raw_ostream &OS, 121 SmallVectorImpl<MCFixup> &Fixups, 122 const MCSubtargetInfo &STI) const { 123 unsigned Opcode = MI.getOpcode(); 124 // Keep track of the current byte being emitted 125 unsigned CurByte = 0; 126 127 if (Opcode == BPF::LD_imm64 || Opcode == BPF::LD_pseudo) { 128 uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI); 129 EmitByte(Value >> 56, CurByte, OS); 130 EmitByte(((Value >> 48) & 0xff), CurByte, OS); 131 EmitLEConstant(0, 2, CurByte, OS); 132 EmitLEConstant(Value & 0xffffFFFF, 4, CurByte, OS); 133 134 const MCOperand &MO = MI.getOperand(1); 135 uint64_t Imm = MO.isImm() ? MO.getImm() : 0; 136 EmitByte(0, CurByte, OS); 137 EmitByte(0, CurByte, OS); 138 EmitLEConstant(0, 2, CurByte, OS); 139 EmitLEConstant(Imm >> 32, 4, CurByte, OS); 140 } else { 141 // Get instruction encoding and emit it 142 uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI); 143 EmitByte(Value >> 56, CurByte, OS); 144 EmitByte((Value >> 48) & 0xff, CurByte, OS); 145 EmitLEConstant((Value >> 32) & 0xffff, 2, CurByte, OS); 146 EmitLEConstant(Value & 0xffffFFFF, 4, CurByte, OS); 147 } 148} 149 150// Encode BPF Memory Operand 151uint64_t BPFMCCodeEmitter::getMemoryOpValue(const MCInst &MI, unsigned Op, 152 SmallVectorImpl<MCFixup> &Fixups, 153 const MCSubtargetInfo &STI) const { 154 uint64_t Encoding; 155 const MCOperand Op1 = MI.getOperand(1); 156 assert(Op1.isReg() && "First operand is not register."); 157 Encoding = MRI.getEncodingValue(Op1.getReg()); 158 Encoding <<= 16; 159 MCOperand Op2 = MI.getOperand(2); 160 assert(Op2.isImm() && "Second operand is not immediate."); 161 Encoding |= Op2.getImm() & 0xffff; 162 return Encoding; 163} 164 165#include "BPFGenMCCodeEmitter.inc" 166