BPFInstPrinter.cpp revision 360784 
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/MCSymbol.h"
18#include "llvm/Support/ErrorHandling.h"
19#include "llvm/Support/FormattedStream.h"
20using namespace llvm;
21
22#define DEBUG_TYPE "asm-printer"
23
24// Include the auto-generated portion of the assembly writer.
25#include "BPFGenAsmWriter.inc"
26
27void BPFInstPrinter::printInst(const MCInst *MI, uint64_t Address,
28                               StringRef Annot, const MCSubtargetInfo &STI,
29                               raw_ostream &O) {
30  printInstruction(MI, Address, O);
31  printAnnotation(O, Annot);
32}
33
34static 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
51void 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
65void 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
86void 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
97void 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