1//=-- BPFMCInstLower.cpp - Convert BPF MachineInstr to an MCInst ------------=//
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 contains code to lower BPF MachineInstrs to their corresponding
11// MCInst records.
12//
13//===----------------------------------------------------------------------===//
14
15#include "BPFMCInstLower.h"
16#include "llvm/CodeGen/AsmPrinter.h"
17#include "llvm/CodeGen/MachineBasicBlock.h"
18#include "llvm/CodeGen/MachineInstr.h"
19#include "llvm/MC/MCAsmInfo.h"
20#include "llvm/MC/MCContext.h"
21#include "llvm/MC/MCExpr.h"
22#include "llvm/MC/MCInst.h"
23#include "llvm/Support/ErrorHandling.h"
24#include "llvm/Support/raw_ostream.h"
25using namespace llvm;
26
27MCSymbol *
28BPFMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
29  return Printer.getSymbol(MO.getGlobal());
30}
31
32MCOperand BPFMCInstLower::LowerSymbolOperand(const MachineOperand &MO,
33                                             MCSymbol *Sym) const {
34
35  const MCExpr *Expr = MCSymbolRefExpr::create(Sym, Ctx);
36
37  if (!MO.isJTI() && MO.getOffset())
38    llvm_unreachable("unknown symbol op");
39
40  return MCOperand::createExpr(Expr);
41}
42
43void BPFMCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
44  OutMI.setOpcode(MI->getOpcode());
45
46  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
47    const MachineOperand &MO = MI->getOperand(i);
48
49    MCOperand MCOp;
50    switch (MO.getType()) {
51    default:
52      MI->dump();
53      llvm_unreachable("unknown operand type");
54    case MachineOperand::MO_Register:
55      // Ignore all implicit register operands.
56      if (MO.isImplicit())
57        continue;
58      MCOp = MCOperand::createReg(MO.getReg());
59      break;
60    case MachineOperand::MO_Immediate:
61      MCOp = MCOperand::createImm(MO.getImm());
62      break;
63    case MachineOperand::MO_MachineBasicBlock:
64      MCOp = MCOperand::createExpr(
65          MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx));
66      break;
67    case MachineOperand::MO_RegisterMask:
68      continue;
69    case MachineOperand::MO_GlobalAddress:
70      MCOp = LowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));
71      break;
72    }
73
74    OutMI.addOperand(MCOp);
75  }
76}
77