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      1 //===-- BPFAsmPrinter.cpp - BPF LLVM assembly writer ----------------------===//
      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 a printer that converts from our internal representation
     11 // of machine-dependent LLVM code to the BPF assembly language.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "BPF.h"
     16 #include "BPFInstrInfo.h"
     17 #include "BPFMCInstLower.h"
     18 #include "BPFTargetMachine.h"
     19 #include "InstPrinter/BPFInstPrinter.h"
     20 #include "llvm/CodeGen/AsmPrinter.h"
     21 #include "llvm/CodeGen/MachineModuleInfo.h"
     22 #include "llvm/CodeGen/MachineFunctionPass.h"
     23 #include "llvm/CodeGen/MachineConstantPool.h"
     24 #include "llvm/CodeGen/MachineInstr.h"
     25 #include "llvm/MC/MCAsmInfo.h"
     26 #include "llvm/MC/MCInst.h"
     27 #include "llvm/MC/MCStreamer.h"
     28 #include "llvm/MC/MCSymbol.h"
     29 #include "llvm/Support/TargetRegistry.h"
     30 #include "llvm/Support/raw_ostream.h"
     31 using namespace llvm;
     32 
     33 #define DEBUG_TYPE "asm-printer"
     34 
     35 namespace {
     36 class BPFAsmPrinter : public AsmPrinter {
     37 public:
     38   explicit BPFAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
     39       : AsmPrinter(TM, std::move(Streamer)) {}
     40 
     41   const char *getPassName() const override { return "BPF Assembly Printer"; }
     42 
     43   void printOperand(const MachineInstr *MI, int OpNum, raw_ostream &O,
     44                     const char *Modifier = nullptr);
     45   void EmitInstruction(const MachineInstr *MI) override;
     46 };
     47 }
     48 
     49 void BPFAsmPrinter::printOperand(const MachineInstr *MI, int OpNum,
     50                                  raw_ostream &O, const char *Modifier) {
     51   const MachineOperand &MO = MI->getOperand(OpNum);
     52 
     53   switch (MO.getType()) {
     54   case MachineOperand::MO_Register:
     55     O << BPFInstPrinter::getRegisterName(MO.getReg());
     56     break;
     57 
     58   case MachineOperand::MO_Immediate:
     59     O << MO.getImm();
     60     break;
     61 
     62   case MachineOperand::MO_MachineBasicBlock:
     63     O << *MO.getMBB()->getSymbol();
     64     break;
     65 
     66   case MachineOperand::MO_GlobalAddress:
     67     O << *getSymbol(MO.getGlobal());
     68     break;
     69 
     70   default:
     71     llvm_unreachable("<unknown operand type>");
     72   }
     73 }
     74 
     75 void BPFAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     76 
     77   BPFMCInstLower MCInstLowering(OutContext, *this);
     78 
     79   MCInst TmpInst;
     80   MCInstLowering.Lower(MI, TmpInst);
     81   EmitToStreamer(*OutStreamer, TmpInst);
     82 }
     83 
     84 // Force static initialization.
     85 extern "C" void LLVMInitializeBPFAsmPrinter() {
     86   RegisterAsmPrinter<BPFAsmPrinter> X(TheBPFleTarget);
     87   RegisterAsmPrinter<BPFAsmPrinter> Y(TheBPFbeTarget);
     88   RegisterAsmPrinter<BPFAsmPrinter> Z(TheBPFTarget);
     89 }
     90