SystemZMCObjectWriter.cpp revision 360784 
1//===-- SystemZMCObjectWriter.cpp - SystemZ ELF writer --------------------===//
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#include "MCTargetDesc/SystemZMCFixups.h"
10#include "MCTargetDesc/SystemZMCTargetDesc.h"
11#include "llvm/BinaryFormat/ELF.h"
12#include "llvm/MC/MCELFObjectWriter.h"
13#include "llvm/MC/MCExpr.h"
14#include "llvm/MC/MCFixup.h"
15#include "llvm/MC/MCObjectWriter.h"
16#include "llvm/MC/MCValue.h"
17#include "llvm/Support/ErrorHandling.h"
18#include <cassert>
19#include <cstdint>
20
21using namespace llvm;
22
23namespace {
24
25class SystemZObjectWriter : public MCELFObjectTargetWriter {
26public:
27  SystemZObjectWriter(uint8_t OSABI);
28  ~SystemZObjectWriter() override = default;
29
30protected:
31  // Override MCELFObjectTargetWriter.
32  unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
33                        const MCFixup &Fixup, bool IsPCRel) const override;
34};
35
36} // end anonymous namespace
37
38SystemZObjectWriter::SystemZObjectWriter(uint8_t OSABI)
39  : MCELFObjectTargetWriter(/*Is64Bit_=*/true, OSABI, ELF::EM_S390,
40                            /*HasRelocationAddend_=*/ true) {}
41
42// Return the relocation type for an absolute value of MCFixupKind Kind.
43static unsigned getAbsoluteReloc(unsigned Kind) {
44  switch (Kind) {
45  case FK_Data_1: return ELF::R_390_8;
46  case FK_Data_2: return ELF::R_390_16;
47  case FK_Data_4: return ELF::R_390_32;
48  case FK_Data_8: return ELF::R_390_64;
49  }
50  llvm_unreachable("Unsupported absolute address");
51}
52
53// Return the relocation type for a PC-relative value of MCFixupKind Kind.
54static unsigned getPCRelReloc(unsigned Kind) {
55  switch (Kind) {
56  case FK_Data_2:                return ELF::R_390_PC16;
57  case FK_Data_4:                return ELF::R_390_PC32;
58  case FK_Data_8:                return ELF::R_390_PC64;
59  case SystemZ::FK_390_PC12DBL:  return ELF::R_390_PC12DBL;
60  case SystemZ::FK_390_PC16DBL:  return ELF::R_390_PC16DBL;
61  case SystemZ::FK_390_PC24DBL:  return ELF::R_390_PC24DBL;
62  case SystemZ::FK_390_PC32DBL:  return ELF::R_390_PC32DBL;
63  }
64  llvm_unreachable("Unsupported PC-relative address");
65}
66
67// Return the R_390_TLS_LE* relocation type for MCFixupKind Kind.
68static unsigned getTLSLEReloc(unsigned Kind) {
69  switch (Kind) {
70  case FK_Data_4: return ELF::R_390_TLS_LE32;
71  case FK_Data_8: return ELF::R_390_TLS_LE64;
72  }
73  llvm_unreachable("Unsupported absolute address");
74}
75
76// Return the R_390_TLS_LDO* relocation type for MCFixupKind Kind.
77static unsigned getTLSLDOReloc(unsigned Kind) {
78  switch (Kind) {
79  case FK_Data_4: return ELF::R_390_TLS_LDO32;
80  case FK_Data_8: return ELF::R_390_TLS_LDO64;
81  }
82  llvm_unreachable("Unsupported absolute address");
83}
84
85// Return the R_390_TLS_LDM* relocation type for MCFixupKind Kind.
86static unsigned getTLSLDMReloc(unsigned Kind) {
87  switch (Kind) {
88  case FK_Data_4: return ELF::R_390_TLS_LDM32;
89  case FK_Data_8: return ELF::R_390_TLS_LDM64;
90  case SystemZ::FK_390_TLS_CALL: return ELF::R_390_TLS_LDCALL;
91  }
92  llvm_unreachable("Unsupported absolute address");
93}
94
95// Return the R_390_TLS_GD* relocation type for MCFixupKind Kind.
96static unsigned getTLSGDReloc(unsigned Kind) {
97  switch (Kind) {
98  case FK_Data_4: return ELF::R_390_TLS_GD32;
99  case FK_Data_8: return ELF::R_390_TLS_GD64;
100  case SystemZ::FK_390_TLS_CALL: return ELF::R_390_TLS_GDCALL;
101  }
102  llvm_unreachable("Unsupported absolute address");
103}
104
105// Return the PLT relocation counterpart of MCFixupKind Kind.
106static unsigned getPLTReloc(unsigned Kind) {
107  switch (Kind) {
108  case SystemZ::FK_390_PC12DBL: return ELF::R_390_PLT12DBL;
109  case SystemZ::FK_390_PC16DBL: return ELF::R_390_PLT16DBL;
110  case SystemZ::FK_390_PC24DBL: return ELF::R_390_PLT24DBL;
111  case SystemZ::FK_390_PC32DBL: return ELF::R_390_PLT32DBL;
112  }
113  llvm_unreachable("Unsupported absolute address");
114}
115
116unsigned SystemZObjectWriter::getRelocType(MCContext &Ctx,
117                                           const MCValue &Target,
118                                           const MCFixup &Fixup,
119                                           bool IsPCRel) const {
120  MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
121  unsigned Kind = Fixup.getKind();
122  switch (Modifier) {
123  case MCSymbolRefExpr::VK_None:
124    if (IsPCRel)
125      return getPCRelReloc(Kind);
126    return getAbsoluteReloc(Kind);
127
128  case MCSymbolRefExpr::VK_NTPOFF:
129    assert(!IsPCRel && "NTPOFF shouldn't be PC-relative");
130    return getTLSLEReloc(Kind);
131
132  case MCSymbolRefExpr::VK_INDNTPOFF:
133    if (IsPCRel && Kind == SystemZ::FK_390_PC32DBL)
134      return ELF::R_390_TLS_IEENT;
135    llvm_unreachable("Only PC-relative INDNTPOFF accesses are supported for now");
136
137  case MCSymbolRefExpr::VK_DTPOFF:
138    assert(!IsPCRel && "DTPOFF shouldn't be PC-relative");
139    return getTLSLDOReloc(Kind);
140
141  case MCSymbolRefExpr::VK_TLSLDM:
142    assert(!IsPCRel && "TLSLDM shouldn't be PC-relative");
143    return getTLSLDMReloc(Kind);
144
145  case MCSymbolRefExpr::VK_TLSGD:
146    assert(!IsPCRel && "TLSGD shouldn't be PC-relative");
147    return getTLSGDReloc(Kind);
148
149  case MCSymbolRefExpr::VK_GOT:
150    if (IsPCRel && Kind == SystemZ::FK_390_PC32DBL)
151      return ELF::R_390_GOTENT;
152    llvm_unreachable("Only PC-relative GOT accesses are supported for now");
153
154  case MCSymbolRefExpr::VK_PLT:
155    assert(IsPCRel && "@PLT shouldt be PC-relative");
156    return getPLTReloc(Kind);
157
158  default:
159    llvm_unreachable("Modifier not supported");
160  }
161}
162
163std::unique_ptr<MCObjectTargetWriter>
164llvm::createSystemZObjectWriter(uint8_t OSABI) {
165  return std::make_unique<SystemZObjectWriter>(OSABI);
166}
167