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