BPFMCInstLower.cpp
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//=-- BPFMCInstLower.cpp - Convert BPF MachineInstr to an MCInst ------------=//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains code to lower BPF MachineInstrs to their corresponding
// MCInst records.
//
//===----------------------------------------------------------------------===//
#include "BPFMCInstLower.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
MCSymbol *
BPFMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
return Printer.getSymbol(MO.getGlobal());
}
MCSymbol *
BPFMCInstLower::GetExternalSymbolSymbol(const MachineOperand &MO) const {
return Printer.GetExternalSymbolSymbol(MO.getSymbolName());
}
MCOperand BPFMCInstLower::LowerSymbolOperand(const MachineOperand &MO,
MCSymbol *Sym) const {
const MCExpr *Expr = MCSymbolRefExpr::create(Sym, Ctx);
if (!MO.isJTI() && MO.getOffset())
llvm_unreachable("unknown symbol op");
return MCOperand::createExpr(Expr);
}
void BPFMCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
OutMI.setOpcode(MI->getOpcode());
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
MCOperand MCOp;
switch (MO.getType()) {
default:
MI->print(errs());
llvm_unreachable("unknown operand type");
case MachineOperand::MO_Register:
// Ignore all implicit register operands.
if (MO.isImplicit())
continue;
MCOp = MCOperand::createReg(MO.getReg());
break;
case MachineOperand::MO_Immediate:
MCOp = MCOperand::createImm(MO.getImm());
break;
case MachineOperand::MO_MachineBasicBlock:
MCOp = MCOperand::createExpr(
MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx));
break;
case MachineOperand::MO_RegisterMask:
continue;
case MachineOperand::MO_ExternalSymbol:
MCOp = LowerSymbolOperand(MO, GetExternalSymbolSymbol(MO));
break;
case MachineOperand::MO_GlobalAddress:
MCOp = LowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));
break;
}
OutMI.addOperand(MCOp);
}
}