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"
24 using namespace llvm;
25
26 MCSymbol *
GetGlobalAddressSymbol(const MachineOperand & MO) const27 BPFMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
28 return Printer.getSymbol(MO.getGlobal());
29 }
30
31 MCSymbol *
GetExternalSymbolSymbol(const MachineOperand & MO) const32 BPFMCInstLower::GetExternalSymbolSymbol(const MachineOperand &MO) const {
33 return Printer.GetExternalSymbolSymbol(MO.getSymbolName());
34 }
35
LowerSymbolOperand(const MachineOperand & MO,MCSymbol * Sym) const36 MCOperand 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
Lower(const MachineInstr * MI,MCInst & OutMI) const47 void 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