On 11/5/20 7:34 AM, H.J. Lu via Gcc-patches wrote: > On Thu, Nov 5, 2020 at 3:37 AM Jozef Lawrynowicz > <joze...@mittosystems.com> wrote: >> On Thu, Nov 05, 2020 at 06:21:21AM -0500, Hans-Peter Nilsson wrote: >>> On Wed, 4 Nov 2020, H.J. Lu wrote: >>>> .retain is ill-defined. For example, >>>> >>>> [hjl@gnu-cfl-2 gcc]$ cat /tmp/x.c >>>> static int xyzzy __attribute__((__used__)); >>>> [hjl@gnu-cfl-2 gcc]$ ./xgcc -B./ -S /tmp/x.c -fcommon >>>> [hjl@gnu-cfl-2 gcc]$ cat x.s >>>> .file "x.c" >>>> .text >>>> .retain xyzzy <<<<<<<<< What does it do? >>>> .local xyzzy >>>> .comm xyzzy,4,4 >>>> .ident "GCC: (GNU) 11.0.0 20201103 (experimental)" >>>> .section .note.GNU-stack,"",@progbits >>>> [hjl@gnu-cfl-2 gcc]$ >>> To answer that question: it's up to the assembler, but for ELF >>> and SHF_GNU_RETAIN, it seems obvious it'd tell the assembler to >>> set SHF_GNU_RETAIN for the section where the symbol ends up. >>> We both know this isn't rocket science with binutils. >> Indeed, and my patch handles it trivially: >> https://sourceware.org/pipermail/binutils/2020-November/113993.html >> >> +void >> +obj_elf_retain (int arg ATTRIBUTE_UNUSED) >> .... snip .... >> + sym = get_sym_from_input_line_and_check (); >> + symbol_get_obj (sym)->retain = 1; >> >> @@ -2624,6 +2704,9 @@ elf_frob_symbol (symbolS *symp, int *puntp) >> } >> } >> >> + if (symbol_get_obj (symp)->retain) >> + elf_section_flags (S_GET_SEGMENT (symp)) |= SHF_GNU_RETAIN; >> + >> /* Double check weak symbols. */ >> if (S_IS_WEAK (symp)) >> { >> >> We could check that the symbol named in the .retain directive has >> already been defined, however this isn't compatible with GCC >> mark_decl_preserved handling, since mark_decl_preserved is called >> emitted before the local symbols are defined in the assembly output >> file. >> >> GAS should at least validate that the symbol named in the .retain >> directive does end up as a symbol though. >> > Don't add .retain.
Why? I don't see why you find it so objectionable. jeff
