================
@@ -940,6 +940,92 @@ ELFFile<ELFT>::decodeBBAddrMap(const Elf_Shdr &Sec, const
Elf_Shdr *RelaSec,
return std::move(AddrMapsOrErr);
}
+template <class ELFT>
+Expected<std::vector<FuncMap>>
+ELFFile<ELFT>::decodeFuncMap(const Elf_Shdr &Sec,
+ const Elf_Shdr *RelaSec) const {
+ bool IsRelocatable = this->getHeader().e_type == ELF::ET_REL;
+
+ // This DenseMap maps the offset of each function (the location of the
+ // reference to the function in the SHT_LLVM_FUNC_MAP section) to the
+ // addend (the location of the function in the text section).
+ llvm::DenseMap<uint64_t, uint64_t> FunctionOffsetTranslations;
+ if (IsRelocatable && RelaSec) {
+ assert(RelaSec &&
+ "Can't read a SHT_LLVM_FUNC_ADDR_MAP section in a relocatable "
+ "object file without providing a relocation section.");
+ Expected<typename ELFFile<ELFT>::Elf_Rela_Range> Relas =
+ this->relas(*RelaSec);
+ if (!Relas)
+ return createError("unable to read relocations for section " +
+ describe(*this, Sec) + ": " +
+ toString(Relas.takeError()));
+ for (typename ELFFile<ELFT>::Elf_Rela Rela : *Relas)
+ FunctionOffsetTranslations[Rela.r_offset] = Rela.r_addend;
----------------
jh7370 wrote:
Not all relocations function in the same way. Naively assuming that the
`r_addend` and `r_offset` work like this is not going to be correct in some
cases. The ELF gABI only describes `r_addend` as a "constant addend used to
compute the value".
Have you looked into the Object/RelocationResolver.h? It's used elsewhere by
llvm-readobj to calculate the values of relocations and may be of some use (see
`printRelocatableStackSizes` for an example usage).
https://github.com/llvm/llvm-project/pull/124333
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