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(TheBPFTarget);
87 }
88