1 //===- Relocations.h -------------------------------------------*- C++ -*-===//
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
7 //===----------------------------------------------------------------------===//
9 #ifndef LLD_ELF_RELOCATIONS_H
10 #define LLD_ELF_RELOCATIONS_H
12 #include "lld/Common/LLVM.h"
13 #include "llvm/ADT/DenseMap.h"
21 class InputSectionBase;
25 // Represents a relocation type, such as R_X86_64_PC32 or R_ARM_THM_CALL.
26 using RelType = uint32_t;
28 // List of target-independent relocation types. Relocations read
29 // from files are converted to these types so that the main code
30 // doesn't have to know about architecture-specific details.
51 R_RELAX_TLS_GD_TO_IE_ABS,
52 R_RELAX_TLS_GD_TO_IE_GOT_OFF,
53 R_RELAX_TLS_GD_TO_IE_GOTPLT,
55 R_RELAX_TLS_GD_TO_LE_NEG,
58 R_RELAX_TLS_LD_TO_LE_ABS,
74 // The following is abstract relocation types used for only one target.
76 // Even though RelExpr is intended to be a target-neutral representation
77 // of a relocation type, there are some relocations whose semantics are
78 // unique to a target. Such relocation are marked with R_<TARGET_NAME>.
79 R_AARCH64_GOT_PAGE_PC,
81 R_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC,
82 R_AARCH64_TLSDESC_PAGE,
87 R_MIPS_GOT_LOCAL_PAGE,
101 // Architecture-neutral representation of relocation.
110 // This function writes undefined symbol diagnostics to an internal buffer.
111 // Call reportUndefinedSymbols() after calling scanRelocations() to emit
113 template <class ELFT> void scanRelocations(InputSectionBase &);
115 template <class ELFT> void reportUndefinedSymbols();
119 struct InputSectionDescription;
123 // Return true if Thunks have been added to OutputSections
124 bool createThunks(ArrayRef<OutputSection *> outputSections);
126 // The number of completed passes of createThunks this permits us
127 // to do one time initialization on Pass 0 and put a limit on the
128 // number of times it can be called to prevent infinite loops.
132 void mergeThunks(ArrayRef<OutputSection *> outputSections);
134 ThunkSection *getISDThunkSec(OutputSection *os, InputSection *isec,
135 InputSectionDescription *isd, uint32_t type,
138 ThunkSection *getISThunkSec(InputSection *isec);
140 void createInitialThunkSections(ArrayRef<OutputSection *> outputSections);
142 std::pair<Thunk *, bool> getThunk(InputSection *isec, Relocation &rel,
145 ThunkSection *addThunkSection(OutputSection *os, InputSectionDescription *,
148 bool normalizeExistingThunk(Relocation &rel, uint64_t src);
150 // Record all the available Thunks for a (Symbol, addend) pair, where Symbol
151 // is represented as a (section, offset) pair. There may be multiple
152 // relocations sharing the same (section, offset + addend) pair. We may revert
153 // a relocation back to its original non-Thunk target, and restore the
154 // original addend, so we cannot fold offset + addend. A nested pair is used
155 // because DenseMapInfo is not specialized for std::tuple.
156 llvm::DenseMap<std::pair<std::pair<SectionBase *, uint64_t>, int64_t>,
157 std::vector<Thunk *>>
158 thunkedSymbolsBySectionAndAddend;
159 llvm::DenseMap<std::pair<Symbol *, int64_t>, std::vector<Thunk *>>
162 // Find a Thunk from the Thunks symbol definition, we can use this to find
163 // the Thunk from a relocation to the Thunks symbol definition.
164 llvm::DenseMap<Symbol *, Thunk *> thunks;
166 // Track InputSections that have an inline ThunkSection placed in front
167 // an inline ThunkSection may have control fall through to the section below
168 // so we need to make sure that there is only one of them.
169 // The Mips LA25 Thunk is an example of an inline ThunkSection.
170 llvm::DenseMap<InputSection *, ThunkSection *> thunkedSections;
173 // Return a int64_t to make sure we get the sign extension out of the way as
174 // early as possible.
175 template <class ELFT>
176 static inline int64_t getAddend(const typename ELFT::Rel &rel) {
179 template <class ELFT>
180 static inline int64_t getAddend(const typename ELFT::Rela &rel) {