1 //===- Target.cpp ---------------------------------------------------------===//
2 //
3 // The LLVM Linker
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Machine-specific things, such as applying relocations, creation of
11 // GOT or PLT entries, etc., are handled in this file.
12 //
13 // Refer the ELF spec for the single letter variables, S, A or P, used
14 // in this file.
15 //
16 // Some functions defined in this file has "relaxTls" as part of their names.
17 // They do peephole optimization for TLS variables by rewriting instructions.
18 // They are not part of the ABI but optional optimization, so you can skip
19 // them if you are not interested in how TLS variables are optimized.
20 // See the following paper for the details.
21 //
22 // Ulrich Drepper, ELF Handling For Thread-Local Storage
23 // http://www.akkadia.org/drepper/tls.pdf
24 //
25 //===----------------------------------------------------------------------===//
26
27 #include "Target.h"
28 #include "InputFiles.h"
29 #include "OutputSections.h"
30 #include "SymbolTable.h"
31 #include "Symbols.h"
32 #include "lld/Common/ErrorHandler.h"
33 #include "llvm/Object/ELF.h"
34
35 using namespace llvm;
36 using namespace llvm::object;
37 using namespace llvm::ELF;
38 using namespace lld;
39 using namespace lld::elf;
40
41 TargetInfo *elf::Target;
42
toString(RelType Type)43 std::string lld::toString(RelType Type) {
44 StringRef S = getELFRelocationTypeName(elf::Config->EMachine, Type);
45 if (S == "Unknown")
46 return ("Unknown (" + Twine(Type) + ")").str();
47 return S;
48 }
49
getTarget()50 TargetInfo *elf::getTarget() {
51 switch (Config->EMachine) {
52 case EM_386:
53 case EM_IAMCU:
54 return getX86TargetInfo();
55 case EM_AARCH64:
56 return getAArch64TargetInfo();
57 case EM_AMDGPU:
58 return getAMDGPUTargetInfo();
59 case EM_ARM:
60 return getARMTargetInfo();
61 case EM_AVR:
62 return getAVRTargetInfo();
63 case EM_HEXAGON:
64 return getHexagonTargetInfo();
65 case EM_MIPS:
66 switch (Config->EKind) {
67 case ELF32LEKind:
68 return getMipsTargetInfo<ELF32LE>();
69 case ELF32BEKind:
70 return getMipsTargetInfo<ELF32BE>();
71 case ELF64LEKind:
72 return getMipsTargetInfo<ELF64LE>();
73 case ELF64BEKind:
74 return getMipsTargetInfo<ELF64BE>();
75 default:
76 llvm_unreachable("unsupported MIPS target");
77 }
78 case EM_MSP430:
79 return getMSP430TargetInfo();
80 case EM_PPC:
81 return getPPCTargetInfo();
82 case EM_PPC64:
83 return getPPC64TargetInfo();
84 case EM_RISCV:
85 return getRISCVTargetInfo();
86 case EM_SPARCV9:
87 return getSPARCV9TargetInfo();
88 case EM_X86_64:
89 if (Config->EKind == ELF32LEKind)
90 return getX32TargetInfo();
91 return getX86_64TargetInfo();
92 }
93 llvm_unreachable("unknown target machine");
94 }
95
getErrPlace(const uint8_t * Loc)96 template <class ELFT> static ErrorPlace getErrPlace(const uint8_t *Loc) {
97 for (InputSectionBase *D : InputSections) {
98 auto *IS = cast<InputSection>(D);
99 if (!IS->getParent())
100 continue;
101
102 uint8_t *ISLoc = IS->getParent()->Loc + IS->OutSecOff;
103 if (ISLoc <= Loc && Loc < ISLoc + IS->getSize())
104 return {IS, IS->template getLocation<ELFT>(Loc - ISLoc) + ": "};
105 }
106 return {};
107 }
108
getErrorPlace(const uint8_t * Loc)109 ErrorPlace elf::getErrorPlace(const uint8_t *Loc) {
110 switch (Config->EKind) {
111 case ELF32LEKind:
112 return getErrPlace<ELF32LE>(Loc);
113 case ELF32BEKind:
114 return getErrPlace<ELF32BE>(Loc);
115 case ELF64LEKind:
116 return getErrPlace<ELF64LE>(Loc);
117 case ELF64BEKind:
118 return getErrPlace<ELF64BE>(Loc);
119 default:
120 llvm_unreachable("unknown ELF type");
121 }
122 }
123
~TargetInfo()124 TargetInfo::~TargetInfo() {}
125
getImplicitAddend(const uint8_t * Buf,RelType Type) const126 int64_t TargetInfo::getImplicitAddend(const uint8_t *Buf, RelType Type) const {
127 return 0;
128 }
129
usesOnlyLowPageBits(RelType Type) const130 bool TargetInfo::usesOnlyLowPageBits(RelType Type) const { return false; }
131
needsThunk(RelExpr Expr,RelType Type,const InputFile * File,uint64_t BranchAddr,const Symbol & S) const132 bool TargetInfo::needsThunk(RelExpr Expr, RelType Type, const InputFile *File,
133 uint64_t BranchAddr, const Symbol &S) const {
134 return false;
135 }
136
adjustPrologueForCrossSplitStack(uint8_t * Loc,uint8_t * End,uint8_t StOther) const137 bool TargetInfo::adjustPrologueForCrossSplitStack(uint8_t *Loc, uint8_t *End,
138 uint8_t StOther) const {
139 llvm_unreachable("Target doesn't support split stacks.");
140 }
141
inBranchRange(RelType Type,uint64_t Src,uint64_t Dst) const142 bool TargetInfo::inBranchRange(RelType Type, uint64_t Src, uint64_t Dst) const {
143 return true;
144 }
145
writeIgotPlt(uint8_t * Buf,const Symbol & S) const146 void TargetInfo::writeIgotPlt(uint8_t *Buf, const Symbol &S) const {
147 writeGotPlt(Buf, S);
148 }
149
adjustRelaxExpr(RelType Type,const uint8_t * Data,RelExpr Expr) const150 RelExpr TargetInfo::adjustRelaxExpr(RelType Type, const uint8_t *Data,
151 RelExpr Expr) const {
152 return Expr;
153 }
154
relaxGot(uint8_t * Loc,uint64_t Val) const155 void TargetInfo::relaxGot(uint8_t *Loc, uint64_t Val) const {
156 llvm_unreachable("Should not have claimed to be relaxable");
157 }
158
relaxTlsGdToLe(uint8_t * Loc,RelType Type,uint64_t Val) const159 void TargetInfo::relaxTlsGdToLe(uint8_t *Loc, RelType Type,
160 uint64_t Val) const {
161 llvm_unreachable("Should not have claimed to be relaxable");
162 }
163
relaxTlsGdToIe(uint8_t * Loc,RelType Type,uint64_t Val) const164 void TargetInfo::relaxTlsGdToIe(uint8_t *Loc, RelType Type,
165 uint64_t Val) const {
166 llvm_unreachable("Should not have claimed to be relaxable");
167 }
168
relaxTlsIeToLe(uint8_t * Loc,RelType Type,uint64_t Val) const169 void TargetInfo::relaxTlsIeToLe(uint8_t *Loc, RelType Type,
170 uint64_t Val) const {
171 llvm_unreachable("Should not have claimed to be relaxable");
172 }
173
relaxTlsLdToLe(uint8_t * Loc,RelType Type,uint64_t Val) const174 void TargetInfo::relaxTlsLdToLe(uint8_t *Loc, RelType Type,
175 uint64_t Val) const {
176 llvm_unreachable("Should not have claimed to be relaxable");
177 }
178
getImageBase()179 uint64_t TargetInfo::getImageBase() {
180 // Use -image-base if set. Fall back to the target default if not.
181 if (Config->ImageBase)
182 return *Config->ImageBase;
183 return Config->Pic ? 0 : DefaultImageBase;
184 }
185