1//===-- SystemZMCObjectWriter.cpp - SystemZ ELF writer --------------------===//
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#include "MCTargetDesc/SystemZMCTargetDesc.h"
11#include "MCTargetDesc/SystemZMCFixups.h"
12#include "llvm/MC/MCELFObjectWriter.h"
13#include "llvm/MC/MCExpr.h"
14#include "llvm/MC/MCValue.h"
15
16using namespace llvm;
17
18namespace {
19class SystemZObjectWriter : public MCELFObjectTargetWriter {
20public:
21  SystemZObjectWriter(uint8_t OSABI);
22
23  virtual ~SystemZObjectWriter();
24
25protected:
26  // Override MCELFObjectTargetWriter.
27  unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
28                        bool IsPCRel) const override;
29};
30} // end anonymous namespace
31
32SystemZObjectWriter::SystemZObjectWriter(uint8_t OSABI)
33  : MCELFObjectTargetWriter(/*Is64Bit=*/true, OSABI, ELF::EM_S390,
34                            /*HasRelocationAddend=*/ true) {}
35
36SystemZObjectWriter::~SystemZObjectWriter() {
37}
38
39// Return the relocation type for an absolute value of MCFixupKind Kind.
40static unsigned getAbsoluteReloc(unsigned Kind) {
41  switch (Kind) {
42  case FK_Data_1: return ELF::R_390_8;
43  case FK_Data_2: return ELF::R_390_16;
44  case FK_Data_4: return ELF::R_390_32;
45  case FK_Data_8: return ELF::R_390_64;
46  }
47  llvm_unreachable("Unsupported absolute address");
48}
49
50// Return the relocation type for a PC-relative value of MCFixupKind Kind.
51static unsigned getPCRelReloc(unsigned Kind) {
52  switch (Kind) {
53  case FK_Data_2:                return ELF::R_390_PC16;
54  case FK_Data_4:                return ELF::R_390_PC32;
55  case FK_Data_8:                return ELF::R_390_PC64;
56  case SystemZ::FK_390_PC16DBL:  return ELF::R_390_PC16DBL;
57  case SystemZ::FK_390_PC32DBL:  return ELF::R_390_PC32DBL;
58  case SystemZ::FK_390_PLT16DBL: return ELF::R_390_PLT16DBL;
59  case SystemZ::FK_390_PLT32DBL: return ELF::R_390_PLT32DBL;
60  }
61  llvm_unreachable("Unsupported PC-relative address");
62}
63
64// Return the R_390_TLS_LE* relocation type for MCFixupKind Kind.
65static unsigned getTLSLEReloc(unsigned Kind) {
66  switch (Kind) {
67  case FK_Data_4: return ELF::R_390_TLS_LE32;
68  case FK_Data_8: return ELF::R_390_TLS_LE64;
69  }
70  llvm_unreachable("Unsupported absolute address");
71}
72
73// Return the PLT relocation counterpart of MCFixupKind Kind.
74static unsigned getPLTReloc(unsigned Kind) {
75  switch (Kind) {
76  case SystemZ::FK_390_PC16DBL: return ELF::R_390_PLT16DBL;
77  case SystemZ::FK_390_PC32DBL: return ELF::R_390_PLT32DBL;
78  }
79  llvm_unreachable("Unsupported absolute address");
80}
81
82unsigned SystemZObjectWriter::GetRelocType(const MCValue &Target,
83                                           const MCFixup &Fixup,
84                                           bool IsPCRel) const {
85  MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
86  unsigned Kind = Fixup.getKind();
87  switch (Modifier) {
88  case MCSymbolRefExpr::VK_None:
89    if (IsPCRel)
90      return getPCRelReloc(Kind);
91    return getAbsoluteReloc(Kind);
92
93  case MCSymbolRefExpr::VK_NTPOFF:
94    assert(!IsPCRel && "NTPOFF shouldn't be PC-relative");
95    return getTLSLEReloc(Kind);
96
97  case MCSymbolRefExpr::VK_GOT:
98    if (IsPCRel && Kind == SystemZ::FK_390_PC32DBL)
99      return ELF::R_390_GOTENT;
100    llvm_unreachable("Only PC-relative GOT accesses are supported for now");
101
102  case MCSymbolRefExpr::VK_PLT:
103    assert(IsPCRel && "@PLT shouldt be PC-relative");
104    return getPLTReloc(Kind);
105
106  default:
107    llvm_unreachable("Modifier not supported");
108  }
109}
110
111MCObjectWriter *llvm::createSystemZObjectWriter(raw_ostream &OS,
112                                                uint8_t OSABI) {
113  MCELFObjectTargetWriter *MOTW = new SystemZObjectWriter(OSABI);
114  return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/false);
115}
116