BPFInstPrinter.cpp revision 353358 
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, raw_ostream &O,
28                               StringRef Annot, const MCSubtargetInfo &STI) {
29  printInstruction(MI, O);
30  printAnnotation(O, Annot);
31}
32
33static void printExpr(const MCExpr *Expr, raw_ostream &O) {
34#ifndef NDEBUG
35  const MCSymbolRefExpr *SRE;
36
37  if (const MCBinaryExpr *BE = dyn_cast<MCBinaryExpr>(Expr))
38    SRE = dyn_cast<MCSymbolRefExpr>(BE->getLHS());
39  else
40    SRE = dyn_cast<MCSymbolRefExpr>(Expr);
41  assert(SRE && "Unexpected MCExpr type.");
42
43  MCSymbolRefExpr::VariantKind Kind = SRE->getKind();
44
45  assert(Kind == MCSymbolRefExpr::VK_None);
46#endif
47  O << *Expr;
48}
49
50void BPFInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
51                                  raw_ostream &O, const char *Modifier) {
52  assert((Modifier == 0 || Modifier[0] == 0) && "No modifiers supported");
53  const MCOperand &Op = MI->getOperand(OpNo);
54  if (Op.isReg()) {
55    O << getRegisterName(Op.getReg());
56  } else if (Op.isImm()) {
57    O << formatImm((int32_t)Op.getImm());
58  } else {
59    assert(Op.isExpr() && "Expected an expression");
60    printExpr(Op.getExpr(), O);
61  }
62}
63
64void BPFInstPrinter::printMemOperand(const MCInst *MI, int OpNo, raw_ostream &O,
65                                     const char *Modifier) {
66  const MCOperand &RegOp = MI->getOperand(OpNo);
67  const MCOperand &OffsetOp = MI->getOperand(OpNo + 1);
68
69  // register
70  assert(RegOp.isReg() && "Register operand not a register");
71  O << getRegisterName(RegOp.getReg());
72
73  // offset
74  if (OffsetOp.isImm()) {
75    auto Imm = OffsetOp.getImm();
76    if (Imm >= 0)
77      O << " + " << formatImm(Imm);
78    else
79      O << " - " << formatImm(-Imm);
80  } else {
81    assert(0 && "Expected an immediate");
82  }
83}
84
85void BPFInstPrinter::printImm64Operand(const MCInst *MI, unsigned OpNo,
86                                       raw_ostream &O) {
87  const MCOperand &Op = MI->getOperand(OpNo);
88  if (Op.isImm())
89    O << formatImm(Op.getImm());
90  else if (Op.isExpr())
91    printExpr(Op.getExpr(), O);
92  else
93    O << Op;
94}
95
96void BPFInstPrinter::printBrTargetOperand(const MCInst *MI, unsigned OpNo,
97                                       raw_ostream &O) {
98  const MCOperand &Op = MI->getOperand(OpNo);
99  if (Op.isImm()) {
100    int16_t Imm = Op.getImm();
101    O << ((Imm >= 0) ? "+" : "") << formatImm(Imm);
102  } else if (Op.isExpr()) {
103    printExpr(Op.getExpr(), O);
104  } else {
105    O << Op;
106  }
107}
108