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Alan Modra authored
dwarf2.c code reasonably assumes that debug info is local to a file, an assumption now violated by gcc, resulting in "DWARF error: invalid abstract instance DIE ref" or wrong details when attempting to print linker error messages with file, function and line reported. This is because find_abstract_instance is only prepared to handle DW_FORM_ref_addr when the .debug_info section referenced is in the current file. When that isn't the case, relocations to access another file's .debug_info will typically be against a symbol defined at the start of that .debug_info section, plus an addend. Since the dwarf2.c code only considers the current file's debug info, that symbol will be undefined, resolving to zero. In effect the ref_addr will wrongly resolve to the current file's .debug_info. This patch avoids the problem by treating relocations in debug sections against undefined symbols in a similar manner to the way relocations against symbols defined in discarded sections are resolved. They result in a zero value (except in .debug_ranges) regardless of the addend. PR 23425 * reloc.c (bfd_generic_get_relocated_section_contents): Zero reloc fields in debug sections when reloc is against an undefined symbol and called from bfd_simple_get_relocated_section_contents or similar. * dwarf2.c (find_abstract_instance): Return true for zero offset DW_FORM_ref_addr without returning values.
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