Add initial support for creating executables that use symbol versioning#670
Add initial support for creating executables that use symbol versioning#670parth-07 wants to merge 1 commit intoqualcomm:mainfrom
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This commit adds primitive support for creating executables that use shared libraries with symbol versioning information. Signed-off-by: Parth Arora <partaror@qti.qualcomm.com>
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some initial comments
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| #ifdef ELD_ENABLE_SYMBOL_VERSIONING | ||
| if (PInfo.isDyn() && PInfo.outSymbol() && PInfo.outSymbol()->shouldIgnore()) | ||
| return false; |
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When for a default versioned symbol such as foo@@V1, both the canonical foo@V1 and the non-canonical foo symbols are selected by the symbol resolution, then we need to discard the non-canonical symbol so that we do not have duplicates in the symbol table. The symbols that were resolving to the non-canonical foo are made to resolve to the canonical symbol foo@V1. All of this happens during the symbol normalization (IRBuilder::normalizeSymbols).
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| void setDynStrTabSection(ELFSection *S) { DynStrTabSection = S; } | ||
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| llvm::StringRef getDynStringTable() const; |
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Move it out of symbol versioning for DynStrTabSection and getDynStringTable
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Can we move it out of ELD_ENABLE_SYMBOL_VERSIONING block when it is required? Currently, we only need these functions for symbol versioning.
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| template <class ELFT> | ||
| llvm::StringRef getSymbolVersionName(uint32_t SymIdx, | ||
| ResolveInfo::Desc SymDesc) const { |
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can we pass in ResolveInfo here ?
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No, this function is called before the ResolveInfo for the symbol is properly created. And also, here we are referring to the input symbol. With ResolveInfo, we refer to the output symbol.
| auto VerNameOffset = | ||
| reinterpret_cast<const typename ELFT::Verdef *>(VerDefs[SymVerID]) | ||
| ->getAux() | ||
| ->vda_name; |
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Is there a function that we can use instead ?
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This functionality is directly from the LLVM. vda_name member is as specified in the official Elf_Verdaux data structure. Why would a function be better here?
| return VerSyms[SymIdx] == getSymbolVersionID(SymIdx); | ||
| } | ||
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| uint16_t getOutputVernAuxID(uint16_t InputVerID) { |
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It cannot be a const function, it may need to resize an internal member.
| uint16_t getOutputVernAuxID(uint16_t InputVerID) { | ||
| if (InputVerID >= OutputVernAuxIDMap.size()) | ||
| OutputVernAuxIDMap.resize(InputVerID + 1, 0); | ||
| return OutputVernAuxIDMap[InputVerID]; |
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Dont use [ as it will create an unnecessary bucket, find and return the value
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The line numbers 98-99 ensures that [ will not create a new bucket.
| OutputVernAuxIDMap[InputVerID] = OutputVerID; | ||
| } | ||
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| const std::vector<uint16_t> &getOutputVernAuxIDMap() const { |
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Adding comments around functions would be helpful to see how it needs to be used
| return OutputVernAuxIDMap; | ||
| } | ||
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| const void *getVerDef(uint16_t InputVerID) { |
2 participants
This commit adds primitive support for creating executables that use
shared libraries with symbol versioning information.