lib/Target/BPF/BPFMCInstLower.cpp

   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 *
  27 BPFMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
  28   return Printer.getSymbol(MO.getGlobal());
  29 }
  30
  31 MCSymbol *
  32 BPFMCInstLower::GetExternalSymbolSymbol(const MachineOperand &MO) const {
  33   return Printer.GetExternalSymbolSymbol(MO.getSymbolName());
  34 }
  35
  36 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
  47 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 }