https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100593
--- Comment #2 from Fangrui Song <i at maskray dot me> --- (In reply to Alexander Monakov from comment #1) > It is not necessary to change -fno-pic code generation to gain most of the > -Bsymbolic benefit It is necessary, otherwise the function address taken from the -Bsymbolic/-Bsymbolic-functions/-Bsymbolic-global-functions shared object may be different from the address taken from the -fno-pic code. The ELF hack is called canonical PLT entry, similar to copy relocations. > as you say, the most important point is to avoid jumping > via PLT trampolines (or, with -fno-plt, GOT loads) for function calls, so > the linker could do -Bsymbolic relaxation for sites where address doesn't > matter (calls and jumps) while keeping a dynamic relocation for address > loads? Under some new option of course, like -Bsymbolic-plt. Right? There are two points: (1) R_*_JUMP_SLOT symbol lookup cost (2) whether call sites get penalized by the PLT indirection. -fno-pic code must use GOT (instead of an absolute relocation) for default visibility external function access to be compatible with a -Bsymbolic/-Bsymbolic-functions/-Bsymbolic-global-functions shared object.
