1 //===-- BPFMCCodeEmitter.cpp - Convert BPF code to machine code -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the BPFMCCodeEmitter class.
12 //===----------------------------------------------------------------------===//
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"
26 #define DEBUG_TYPE "mccodeemitter"
29 class BPFMCCodeEmitter : public MCCodeEmitter {
30 BPFMCCodeEmitter(const BPFMCCodeEmitter &) = delete;
31 void operator=(const BPFMCCodeEmitter &) = delete;
32 const MCRegisterInfo &MRI;
35 BPFMCCodeEmitter(const MCRegisterInfo &mri) : MRI(mri) {}
37 ~BPFMCCodeEmitter() {}
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;
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;
51 uint64_t getMemoryOpValue(const MCInst &MI, unsigned Op,
52 SmallVectorImpl<MCFixup> &Fixups,
53 const MCSubtargetInfo &STI) const;
55 void EncodeInstruction(const MCInst &MI, raw_ostream &OS,
56 SmallVectorImpl<MCFixup> &Fixups,
57 const MCSubtargetInfo &STI) const override;
61 MCCodeEmitter *llvm::createBPFMCCodeEmitter(const MCInstrInfo &MCII,
62 const MCRegisterInfo &MRI,
63 const MCSubtargetInfo &STI,
65 return new BPFMCCodeEmitter(MRI);
68 unsigned BPFMCCodeEmitter::getMachineOpValue(const MCInst &MI,
70 SmallVectorImpl<MCFixup> &Fixups,
71 const MCSubtargetInfo &STI) const {
73 return MRI.getEncodingValue(MO.getReg());
75 return static_cast<unsigned>(MO.getImm());
79 const MCExpr *Expr = MO.getExpr();
80 MCExpr::ExprKind Kind = Expr->getKind();
82 assert(Kind == MCExpr::SymbolRef);
84 if (MI.getOpcode() == BPF::JAL)
86 Fixups.push_back(MCFixup::Create(0, Expr, FK_SecRel_4));
87 else if (MI.getOpcode() == BPF::LD_imm64)
88 Fixups.push_back(MCFixup::Create(0, Expr, FK_SecRel_8));
91 Fixups.push_back(MCFixup::Create(0, Expr, FK_PCRel_2));
96 // Emit one byte through output stream
97 void EmitByte(unsigned char C, unsigned &CurByte, raw_ostream &OS) {
102 // Emit a series of bytes (little endian)
103 void EmitLEConstant(uint64_t Val, unsigned Size, unsigned &CurByte,
105 assert(Size <= 8 && "size too big in emit constant");
107 for (unsigned i = 0; i != Size; ++i) {
108 EmitByte(Val & 255, CurByte, OS);
113 // Emit a series of bytes (big endian)
114 void EmitBEConstant(uint64_t Val, unsigned Size, unsigned &CurByte,
116 assert(Size <= 8 && "size too big in emit constant");
118 for (int i = (Size - 1) * 8; i >= 0; i -= 8)
119 EmitByte((Val >> i) & 255, CurByte, OS);
122 void BPFMCCodeEmitter::EncodeInstruction(const MCInst &MI, raw_ostream &OS,
123 SmallVectorImpl<MCFixup> &Fixups,
124 const MCSubtargetInfo &STI) const {
125 unsigned Opcode = MI.getOpcode();
126 // Keep track of the current byte being emitted
127 unsigned CurByte = 0;
129 if (Opcode == BPF::LD_imm64) {
130 uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI);
131 EmitByte(Value >> 56, CurByte, OS);
132 EmitByte(((Value >> 48) & 0xff), CurByte, OS);
133 EmitLEConstant(0, 2, CurByte, OS);
134 EmitLEConstant(Value & 0xffffFFFF, 4, CurByte, OS);
136 const MCOperand &MO = MI.getOperand(1);
137 uint64_t Imm = MO.isImm() ? MO.getImm() : 0;
138 EmitByte(0, CurByte, OS);
139 EmitByte(0, CurByte, OS);
140 EmitLEConstant(0, 2, CurByte, OS);
141 EmitLEConstant(Imm >> 32, 4, CurByte, OS);
143 // Get instruction encoding and emit it
144 uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI);
145 EmitByte(Value >> 56, CurByte, OS);
146 EmitByte((Value >> 48) & 0xff, CurByte, OS);
147 EmitLEConstant((Value >> 32) & 0xffff, 2, CurByte, OS);
148 EmitLEConstant(Value & 0xffffFFFF, 4, CurByte, OS);
152 // Encode BPF Memory Operand
153 uint64_t BPFMCCodeEmitter::getMemoryOpValue(const MCInst &MI, unsigned Op,
154 SmallVectorImpl<MCFixup> &Fixups,
155 const MCSubtargetInfo &STI) const {
157 const MCOperand Op1 = MI.getOperand(1);
158 assert(Op1.isReg() && "First operand is not register.");
159 Encoding = MRI.getEncodingValue(Op1.getReg());
161 MCOperand Op2 = MI.getOperand(2);
162 assert(Op2.isImm() && "Second operand is not immediate.");
163 Encoding |= Op2.getImm() & 0xffff;
167 #include "BPFGenMCCodeEmitter.inc"