1//=-- BPFMCInstLower.cpp - Convert BPF MachineInstr to an MCInst ------------=//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains code to lower BPF MachineInstrs to their corresponding
10// MCInst records.
11//
12//===----------------------------------------------------------------------===//
13
14#include "BPFMCInstLower.h"
15#include "llvm/CodeGen/AsmPrinter.h"
16#include "llvm/CodeGen/MachineBasicBlock.h"
17#include "llvm/CodeGen/MachineInstr.h"
18#include "llvm/MC/MCAsmInfo.h"
19#include "llvm/MC/MCContext.h"
20#include "llvm/MC/MCExpr.h"
21#include "llvm/MC/MCInst.h"
22#include "llvm/Support/ErrorHandling.h"
23#include "llvm/Support/raw_ostream.h"
24using namespace llvm;
25
26MCSymbol *
27BPFMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
28  return Printer.getSymbol(MO.getGlobal());
29}
30
31MCSymbol *
32BPFMCInstLower::GetExternalSymbolSymbol(const MachineOperand &MO) const {
33  return Printer.GetExternalSymbolSymbol(MO.getSymbolName());
34}
35
36MCOperand BPFMCInstLower::LowerSymbolOperand(const MachineOperand &MO,
37                                             MCSymbol *Sym) const {
38
39  const MCExpr *Expr = MCSymbolRefExpr::create(Sym, Ctx);
40
41  if (!MO.isJTI() && MO.getOffset())
42    llvm_unreachable("unknown symbol op");
43
44  return MCOperand::createExpr(Expr);
45}
46
47void BPFMCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
48  OutMI.setOpcode(MI->getOpcode());
49
50  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
51    const MachineOperand &MO = MI->getOperand(i);
52
53    MCOperand MCOp;
54    switch (MO.getType()) {
55    default:
56      MI->print(errs());
57      llvm_unreachable("unknown operand type");
58    case MachineOperand::MO_Register:
59      // Ignore all implicit register operands.
60      if (MO.isImplicit())
61        continue;
62      MCOp = MCOperand::createReg(MO.getReg());
63      break;
64    case MachineOperand::MO_Immediate:
65      MCOp = MCOperand::createImm(MO.getImm());
66      break;
67    case MachineOperand::MO_MachineBasicBlock:
68      MCOp = MCOperand::createExpr(
69          MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx));
70      break;
71    case MachineOperand::MO_RegisterMask:
72      continue;
73    case MachineOperand::MO_ExternalSymbol:
74      MCOp = LowerSymbolOperand(MO, GetExternalSymbolSymbol(MO));
75      break;
76    case MachineOperand::MO_GlobalAddress:
77      MCOp = LowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));
78      break;
79    }
80
81    OutMI.addOperand(MCOp);
82  }
83}
84