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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 
16 using namespace llvm;
17 
18 namespace {
19 class SystemZObjectWriter : public MCELFObjectTargetWriter {
20 public:
21   SystemZObjectWriter(uint8_t OSABI);
22 
23   ~SystemZObjectWriter() override;
24 
25 protected:
26   // Override MCELFObjectTargetWriter.
27   unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
28                         const MCFixup &Fixup, bool IsPCRel) const override;
29 };
30 } // end anonymous namespace
31 
SystemZObjectWriter(uint8_t OSABI)32 SystemZObjectWriter::SystemZObjectWriter(uint8_t OSABI)
33   : MCELFObjectTargetWriter(/*Is64Bit=*/true, OSABI, ELF::EM_S390,
34                             /*HasRelocationAddend=*/ true) {}
35 
~SystemZObjectWriter()36 SystemZObjectWriter::~SystemZObjectWriter() {
37 }
38 
39 // Return the relocation type for an absolute value of MCFixupKind Kind.
getAbsoluteReloc(unsigned Kind)40 static 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.
getPCRelReloc(unsigned Kind)51 static 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   }
59   llvm_unreachable("Unsupported PC-relative address");
60 }
61 
62 // Return the R_390_TLS_LE* relocation type for MCFixupKind Kind.
getTLSLEReloc(unsigned Kind)63 static unsigned getTLSLEReloc(unsigned Kind) {
64   switch (Kind) {
65   case FK_Data_4: return ELF::R_390_TLS_LE32;
66   case FK_Data_8: return ELF::R_390_TLS_LE64;
67   }
68   llvm_unreachable("Unsupported absolute address");
69 }
70 
71 // Return the R_390_TLS_LDO* relocation type for MCFixupKind Kind.
getTLSLDOReloc(unsigned Kind)72 static unsigned getTLSLDOReloc(unsigned Kind) {
73   switch (Kind) {
74   case FK_Data_4: return ELF::R_390_TLS_LDO32;
75   case FK_Data_8: return ELF::R_390_TLS_LDO64;
76   }
77   llvm_unreachable("Unsupported absolute address");
78 }
79 
80 // Return the R_390_TLS_LDM* relocation type for MCFixupKind Kind.
getTLSLDMReloc(unsigned Kind)81 static unsigned getTLSLDMReloc(unsigned Kind) {
82   switch (Kind) {
83   case FK_Data_4: return ELF::R_390_TLS_LDM32;
84   case FK_Data_8: return ELF::R_390_TLS_LDM64;
85   case SystemZ::FK_390_TLS_CALL: return ELF::R_390_TLS_LDCALL;
86   }
87   llvm_unreachable("Unsupported absolute address");
88 }
89 
90 // Return the R_390_TLS_GD* relocation type for MCFixupKind Kind.
getTLSGDReloc(unsigned Kind)91 static unsigned getTLSGDReloc(unsigned Kind) {
92   switch (Kind) {
93   case FK_Data_4: return ELF::R_390_TLS_GD32;
94   case FK_Data_8: return ELF::R_390_TLS_GD64;
95   case SystemZ::FK_390_TLS_CALL: return ELF::R_390_TLS_GDCALL;
96   }
97   llvm_unreachable("Unsupported absolute address");
98 }
99 
100 // Return the PLT relocation counterpart of MCFixupKind Kind.
getPLTReloc(unsigned Kind)101 static unsigned getPLTReloc(unsigned Kind) {
102   switch (Kind) {
103   case SystemZ::FK_390_PC16DBL: return ELF::R_390_PLT16DBL;
104   case SystemZ::FK_390_PC32DBL: return ELF::R_390_PLT32DBL;
105   }
106   llvm_unreachable("Unsupported absolute address");
107 }
108 
getRelocType(MCContext & Ctx,const MCValue & Target,const MCFixup & Fixup,bool IsPCRel) const109 unsigned SystemZObjectWriter::getRelocType(MCContext &Ctx,
110                                            const MCValue &Target,
111                                            const MCFixup &Fixup,
112                                            bool IsPCRel) const {
113   MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
114   unsigned Kind = Fixup.getKind();
115   switch (Modifier) {
116   case MCSymbolRefExpr::VK_None:
117     if (IsPCRel)
118       return getPCRelReloc(Kind);
119     return getAbsoluteReloc(Kind);
120 
121   case MCSymbolRefExpr::VK_NTPOFF:
122     assert(!IsPCRel && "NTPOFF shouldn't be PC-relative");
123     return getTLSLEReloc(Kind);
124 
125   case MCSymbolRefExpr::VK_INDNTPOFF:
126     if (IsPCRel && Kind == SystemZ::FK_390_PC32DBL)
127       return ELF::R_390_TLS_IEENT;
128     llvm_unreachable("Only PC-relative INDNTPOFF accesses are supported for now");
129 
130   case MCSymbolRefExpr::VK_DTPOFF:
131     assert(!IsPCRel && "DTPOFF shouldn't be PC-relative");
132     return getTLSLDOReloc(Kind);
133 
134   case MCSymbolRefExpr::VK_TLSLDM:
135     assert(!IsPCRel && "TLSLDM shouldn't be PC-relative");
136     return getTLSLDMReloc(Kind);
137 
138   case MCSymbolRefExpr::VK_TLSGD:
139     assert(!IsPCRel && "TLSGD shouldn't be PC-relative");
140     return getTLSGDReloc(Kind);
141 
142   case MCSymbolRefExpr::VK_GOT:
143     if (IsPCRel && Kind == SystemZ::FK_390_PC32DBL)
144       return ELF::R_390_GOTENT;
145     llvm_unreachable("Only PC-relative GOT accesses are supported for now");
146 
147   case MCSymbolRefExpr::VK_PLT:
148     assert(IsPCRel && "@PLT shouldt be PC-relative");
149     return getPLTReloc(Kind);
150 
151   default:
152     llvm_unreachable("Modifier not supported");
153   }
154 }
155 
createSystemZObjectWriter(raw_pwrite_stream & OS,uint8_t OSABI)156 MCObjectWriter *llvm::createSystemZObjectWriter(raw_pwrite_stream &OS,
157                                                 uint8_t OSABI) {
158   MCELFObjectTargetWriter *MOTW = new SystemZObjectWriter(OSABI);
159   return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/false);
160 }
161