LoongArch: Fix relocation of ignored undefined symbols
Corrects how ignored undefined symbols are handled in LoongArch to prevent BFD assertions.
This patch resolves an issue in LoongArch where ignored undefined symbols, when not resolved locally, were treated as dynamically resolved. This led to a BFD assertion failure when branch and call relocations requested non-existent PLT entries. The fix classifies ignored symbols without dynamic entries as constants, while those with dynamic entries remain dynamically resolved to maintain compatibility with shared links.
In Details
This patch modifies elfnn-loongarch.c to correctly handle ignored undefined symbols in LoongArch. Previously, symbols marked RM_IGNORE that didn't resolve locally were treated as dynamic, leading to PLT lookups and assertion failures. The change differentiates between ignored symbols with and without dynamic entries: those without dynamic entries are now treated as constants, preventing unnecessary PLT resolution. This is crucial for branch and call instructions targeting such symbols.
- relocation
- Information in an object file that describes how to modify (relocate) certain memory addresses when the code or data is loaded into memory at a different address than the one it was compiled for. This is crucial for position-independent code and dynamic linking.
- undefined symbol
- A symbol (like a function or variable name) that is referenced in one object file but not defined within it. The linker's job is to resolve these references to definitions in other object files or libraries.
- PLT
- Procedure Linkage Table. A table in an executable or shared library used to resolve calls to functions in dynamically linked libraries at runtime.
- BFD assertion
- An assertion failure within the Binary File Descriptor (BFD) library, which is part of binutils. Assertions are checks that must be true for the program to function correctly; failure indicates a bug.
- dynamic symbol entry
- An entry in the symbol table of an object file that provides information for dynamic linking, such as the symbol's value and whether it needs to be resolved at runtime.