1 //===-- BPFAsmPrinter.cpp - BPF LLVM assembly writer ----------------------===//
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 a printer that converts from our internal representation
10 // of machine-dependent LLVM code to the BPF assembly language.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "BPF.h"
15 #include "BPFInstrInfo.h"
16 #include "BPFMCInstLower.h"
17 #include "BPFTargetMachine.h"
18 #include "BTFDebug.h"
19 #include "MCTargetDesc/BPFInstPrinter.h"
20 #include "TargetInfo/BPFTargetInfo.h"
21 #include "llvm/CodeGen/AsmPrinter.h"
22 #include "llvm/CodeGen/MachineConstantPool.h"
23 #include "llvm/CodeGen/MachineFunctionPass.h"
24 #include "llvm/CodeGen/MachineInstr.h"
25 #include "llvm/CodeGen/MachineModuleInfo.h"
26 #include "llvm/IR/Module.h"
27 #include "llvm/MC/MCAsmInfo.h"
28 #include "llvm/MC/MCInst.h"
29 #include "llvm/MC/MCStreamer.h"
30 #include "llvm/MC/MCSymbol.h"
31 #include "llvm/MC/TargetRegistry.h"
32 #include "llvm/Support/raw_ostream.h"
33 using namespace llvm;
34
35 #define DEBUG_TYPE "asm-printer"
36
37 namespace {
38 class BPFAsmPrinter : public AsmPrinter {
39 public:
BPFAsmPrinter(TargetMachine & TM,std::unique_ptr<MCStreamer> Streamer)40 explicit BPFAsmPrinter(TargetMachine &TM,
41 std::unique_ptr<MCStreamer> Streamer)
42 : AsmPrinter(TM, std::move(Streamer)), BTF(nullptr) {}
43
getPassName() const44 StringRef getPassName() const override { return "BPF Assembly Printer"; }
45 bool doInitialization(Module &M) override;
46 void printOperand(const MachineInstr *MI, int OpNum, raw_ostream &O);
47 bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
48 const char *ExtraCode, raw_ostream &O) override;
49 bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNum,
50 const char *ExtraCode, raw_ostream &O) override;
51
52 void emitInstruction(const MachineInstr *MI) override;
53
54 private:
55 BTFDebug *BTF;
56 };
57 } // namespace
58
doInitialization(Module & M)59 bool BPFAsmPrinter::doInitialization(Module &M) {
60 AsmPrinter::doInitialization(M);
61
62 // Only emit BTF when debuginfo available.
63 if (MAI->doesSupportDebugInformation() && !M.debug_compile_units().empty()) {
64 BTF = new BTFDebug(this);
65 DebugHandlers.push_back(std::unique_ptr<BTFDebug>(BTF));
66 }
67
68 return false;
69 }
70
printOperand(const MachineInstr * MI,int OpNum,raw_ostream & O)71 void BPFAsmPrinter::printOperand(const MachineInstr *MI, int OpNum,
72 raw_ostream &O) {
73 const MachineOperand &MO = MI->getOperand(OpNum);
74
75 switch (MO.getType()) {
76 case MachineOperand::MO_Register:
77 O << BPFInstPrinter::getRegisterName(MO.getReg());
78 break;
79
80 case MachineOperand::MO_Immediate:
81 O << MO.getImm();
82 break;
83
84 case MachineOperand::MO_MachineBasicBlock:
85 O << *MO.getMBB()->getSymbol();
86 break;
87
88 case MachineOperand::MO_GlobalAddress:
89 O << *getSymbol(MO.getGlobal());
90 break;
91
92 case MachineOperand::MO_BlockAddress: {
93 MCSymbol *BA = GetBlockAddressSymbol(MO.getBlockAddress());
94 O << BA->getName();
95 break;
96 }
97
98 case MachineOperand::MO_ExternalSymbol:
99 O << *GetExternalSymbolSymbol(MO.getSymbolName());
100 break;
101
102 case MachineOperand::MO_JumpTableIndex:
103 case MachineOperand::MO_ConstantPoolIndex:
104 default:
105 llvm_unreachable("<unknown operand type>");
106 }
107 }
108
PrintAsmOperand(const MachineInstr * MI,unsigned OpNo,const char * ExtraCode,raw_ostream & O)109 bool BPFAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
110 const char *ExtraCode, raw_ostream &O) {
111 if (ExtraCode && ExtraCode[0])
112 return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, O);
113
114 printOperand(MI, OpNo, O);
115 return false;
116 }
117
PrintAsmMemoryOperand(const MachineInstr * MI,unsigned OpNum,const char * ExtraCode,raw_ostream & O)118 bool BPFAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
119 unsigned OpNum, const char *ExtraCode,
120 raw_ostream &O) {
121 assert(OpNum + 1 < MI->getNumOperands() && "Insufficient operands");
122 const MachineOperand &BaseMO = MI->getOperand(OpNum);
123 const MachineOperand &OffsetMO = MI->getOperand(OpNum + 1);
124 assert(BaseMO.isReg() && "Unexpected base pointer for inline asm memory operand.");
125 assert(OffsetMO.isImm() && "Unexpected offset for inline asm memory operand.");
126 int Offset = OffsetMO.getImm();
127
128 if (ExtraCode)
129 return true; // Unknown modifier.
130
131 if (Offset < 0)
132 O << "(" << BPFInstPrinter::getRegisterName(BaseMO.getReg()) << " - " << -Offset << ")";
133 else
134 O << "(" << BPFInstPrinter::getRegisterName(BaseMO.getReg()) << " + " << Offset << ")";
135
136 return false;
137 }
138
emitInstruction(const MachineInstr * MI)139 void BPFAsmPrinter::emitInstruction(const MachineInstr *MI) {
140 BPF_MC::verifyInstructionPredicates(MI->getOpcode(),
141 getSubtargetInfo().getFeatureBits());
142
143 MCInst TmpInst;
144
145 if (!BTF || !BTF->InstLower(MI, TmpInst)) {
146 BPFMCInstLower MCInstLowering(OutContext, *this);
147 MCInstLowering.Lower(MI, TmpInst);
148 }
149 EmitToStreamer(*OutStreamer, TmpInst);
150 }
151
152 // Force static initialization.
LLVMInitializeBPFAsmPrinter()153 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFAsmPrinter() {
154 RegisterAsmPrinter<BPFAsmPrinter> X(getTheBPFleTarget());
155 RegisterAsmPrinter<BPFAsmPrinter> Y(getTheBPFbeTarget());
156 RegisterAsmPrinter<BPFAsmPrinter> Z(getTheBPFTarget());
157 }
158