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