1 //===-- BPFInstPrinter.cpp - Convert BPF MCInst to asm syntax -------------===//
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 class prints an BPF MCInst to a .s file.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "MCTargetDesc/BPFInstPrinter.h"
14 #include "llvm/MC/MCAsmInfo.h"
15 #include "llvm/MC/MCExpr.h"
16 #include "llvm/MC/MCInst.h"
17 #include "llvm/MC/MCRegister.h"
18 #include "llvm/MC/MCSymbol.h"
19 #include "llvm/Support/Casting.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include "llvm/Support/FormattedStream.h"
22 using namespace llvm;
23 
24 #define DEBUG_TYPE "asm-printer"
25 
26 // Include the auto-generated portion of the assembly writer.
27 #include "BPFGenAsmWriter.inc"
28 
29 void BPFInstPrinter::printInst(const MCInst *MI, uint64_t Address,
30                                StringRef Annot, const MCSubtargetInfo &STI,
31                                raw_ostream &O) {
32   printInstruction(MI, Address, O);
33   printAnnotation(O, Annot);
34 }
35 
36 static void printExpr(const MCExpr *Expr, raw_ostream &O) {
37 #ifndef NDEBUG
38   const MCSymbolRefExpr *SRE;
39 
40   if (const MCBinaryExpr *BE = dyn_cast<MCBinaryExpr>(Expr))
41     SRE = dyn_cast<MCSymbolRefExpr>(BE->getLHS());
42   else
43     SRE = dyn_cast<MCSymbolRefExpr>(Expr);
44   assert(SRE && "Unexpected MCExpr type.");
45 
46   MCSymbolRefExpr::VariantKind Kind = SRE->getKind();
47 
48   assert(Kind == MCSymbolRefExpr::VK_None);
49 #endif
50   O << *Expr;
51 }
52 
53 void BPFInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
54                                   raw_ostream &O, const char *Modifier) {
55   assert((Modifier == nullptr || Modifier[0] == 0) && "No modifiers supported");
56   const MCOperand &Op = MI->getOperand(OpNo);
57   if (Op.isReg()) {
58     O << getRegisterName(Op.getReg());
59   } else if (Op.isImm()) {
60     O << formatImm((int32_t)Op.getImm());
61   } else {
62     assert(Op.isExpr() && "Expected an expression");
63     printExpr(Op.getExpr(), O);
64   }
65 }
66 
67 void BPFInstPrinter::printMemOperand(const MCInst *MI, int OpNo, raw_ostream &O,
68                                      const char *Modifier) {
69   const MCOperand &RegOp = MI->getOperand(OpNo);
70   const MCOperand &OffsetOp = MI->getOperand(OpNo + 1);
71 
72   // register
73   assert(RegOp.isReg() && "Register operand not a register");
74   O << getRegisterName(RegOp.getReg());
75 
76   // offset
77   if (OffsetOp.isImm()) {
78     auto Imm = OffsetOp.getImm();
79     if (Imm >= 0)
80       O << " + " << formatImm(Imm);
81     else
82       O << " - " << formatImm(-Imm);
83   } else {
84     assert(0 && "Expected an immediate");
85   }
86 }
87 
88 void BPFInstPrinter::printImm64Operand(const MCInst *MI, unsigned OpNo,
89                                        raw_ostream &O) {
90   const MCOperand &Op = MI->getOperand(OpNo);
91   if (Op.isImm())
92     O << formatImm(Op.getImm());
93   else if (Op.isExpr())
94     printExpr(Op.getExpr(), O);
95   else
96     O << Op;
97 }
98 
99 void BPFInstPrinter::printBrTargetOperand(const MCInst *MI, unsigned OpNo,
100                                        raw_ostream &O) {
101   const MCOperand &Op = MI->getOperand(OpNo);
102   if (Op.isImm()) {
103     int16_t Imm = Op.getImm();
104     O << ((Imm >= 0) ? "+" : "") << formatImm(Imm);
105   } else if (Op.isExpr()) {
106     printExpr(Op.getExpr(), O);
107   } else {
108     O << Op;
109   }
110 }
111