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
14 #include "BPF.h"
15 #include "MCTargetDesc/BPFInstPrinter.h"
16 #include "llvm/MC/MCAsmInfo.h"
17 #include "llvm/MC/MCExpr.h"
18 #include "llvm/MC/MCInst.h"
19 #include "llvm/MC/MCRegister.h"
20 #include "llvm/MC/MCSymbol.h"
21 #include "llvm/Support/Casting.h"
22 #include "llvm/Support/ErrorHandling.h"
23 #include "llvm/Support/FormattedStream.h"
24 using namespace llvm;
25
26 #define DEBUG_TYPE "asm-printer"
27
28 // Include the auto-generated portion of the assembly writer.
29 #include "BPFGenAsmWriter.inc"
30
printInst(const MCInst * MI,uint64_t Address,StringRef Annot,const MCSubtargetInfo & STI,raw_ostream & O)31 void BPFInstPrinter::printInst(const MCInst *MI, uint64_t Address,
32 StringRef Annot, const MCSubtargetInfo &STI,
33 raw_ostream &O) {
34 printInstruction(MI, Address, O);
35 printAnnotation(O, Annot);
36 }
37
printExpr(const MCExpr * Expr,raw_ostream & O)38 static void printExpr(const MCExpr *Expr, raw_ostream &O) {
39 const MCSymbolRefExpr *SRE;
40
41 if (const MCBinaryExpr *BE = dyn_cast<MCBinaryExpr>(Expr))
42 SRE = dyn_cast<MCSymbolRefExpr>(BE->getLHS());
43 else
44 SRE = dyn_cast<MCSymbolRefExpr>(Expr);
45 if (!SRE)
46 report_fatal_error("Unexpected MCExpr type.");
47
48 #ifndef NDEBUG
49 MCSymbolRefExpr::VariantKind Kind = SRE->getKind();
50
51 assert(Kind == MCSymbolRefExpr::VK_None);
52 #endif
53 O << *Expr;
54 }
55
printOperand(const MCInst * MI,unsigned OpNo,raw_ostream & O,const char * Modifier)56 void BPFInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
57 raw_ostream &O, const char *Modifier) {
58 assert((Modifier == nullptr || Modifier[0] == 0) && "No modifiers supported");
59 const MCOperand &Op = MI->getOperand(OpNo);
60 if (Op.isReg()) {
61 O << getRegisterName(Op.getReg());
62 } else if (Op.isImm()) {
63 O << formatImm((int32_t)Op.getImm());
64 } else {
65 assert(Op.isExpr() && "Expected an expression");
66 printExpr(Op.getExpr(), O);
67 }
68 }
69
printMemOperand(const MCInst * MI,int OpNo,raw_ostream & O,const char * Modifier)70 void BPFInstPrinter::printMemOperand(const MCInst *MI, int OpNo, raw_ostream &O,
71 const char *Modifier) {
72 const MCOperand &RegOp = MI->getOperand(OpNo);
73 const MCOperand &OffsetOp = MI->getOperand(OpNo + 1);
74
75 // register
76 assert(RegOp.isReg() && "Register operand not a register");
77 O << getRegisterName(RegOp.getReg());
78
79 // offset
80 if (OffsetOp.isImm()) {
81 auto Imm = OffsetOp.getImm();
82 if (Imm >= 0)
83 O << " + " << formatImm(Imm);
84 else
85 O << " - " << formatImm(-Imm);
86 } else {
87 assert(0 && "Expected an immediate");
88 }
89 }
90
printImm64Operand(const MCInst * MI,unsigned OpNo,raw_ostream & O)91 void BPFInstPrinter::printImm64Operand(const MCInst *MI, unsigned OpNo,
92 raw_ostream &O) {
93 const MCOperand &Op = MI->getOperand(OpNo);
94 if (Op.isImm())
95 O << formatImm(Op.getImm());
96 else if (Op.isExpr())
97 printExpr(Op.getExpr(), O);
98 else
99 O << Op;
100 }
101
printBrTargetOperand(const MCInst * MI,unsigned OpNo,raw_ostream & O)102 void BPFInstPrinter::printBrTargetOperand(const MCInst *MI, unsigned OpNo,
103 raw_ostream &O) {
104 const MCOperand &Op = MI->getOperand(OpNo);
105 if (Op.isImm()) {
106 if (MI->getOpcode() == BPF::JMPL) {
107 int32_t Imm = Op.getImm();
108 O << ((Imm >= 0) ? "+" : "") << formatImm(Imm);
109 } else {
110 int16_t Imm = Op.getImm();
111 O << ((Imm >= 0) ? "+" : "") << formatImm(Imm);
112 }
113 } else if (Op.isExpr()) {
114 printExpr(Op.getExpr(), O);
115 } else {
116 O << Op;
117 }
118 }
119