On Wed, Sep 30, 2020 at 03:13:15PM -0700, H.J. Lu via Binutils wrote:
> On Mon, Sep 28, 2020 at 6:28 AM Jozef Lawrynowicz
> <jozef.l@mittosystems.com> wrote:
> >
> > The attached patch is version 2 of the SHF_GNU_RETAIN patch that was
> > previously discussed here:
> > https://sourceware.org/pipermail/binutils/2020-September/113406.html
> >
> > The following changes have been made:
> > - Removed the .retain directive
> > - The assembler will create different input sections for sections with
> >   the same name but SHF_GNU_RETAIN set/unset (thanks to H.J. for that).
> >   This means the linker will be able to do a better job garbage
> >   collecting input sections, as the "retain" attribute applied to a
> >   symbol declaration in the source code will not cause other parts of
> >   the program that are not required, but are in the same section, to be
> >   unnecessarily retained.
> > - Added GNU OSABI handling (also thanks to H.J.).
> >
> > I've successfully regtested the patch for the Binutils, GAS and LD
> > testsuites for the following targets:
> >
> > aarch64-elf arc-elf arm-eabi arm-elf avr-elf bfin-elf cr16-elf cris-elf
> > crx-elf csky-elf d10v-elf d30v-elf dlx-elf epiphany-elf fr30-elf frv-elf
> > ft32-elf h8300-elf hppa-elf i386-elf ip2k-elf iq2000-elf lm32-elf
> > m32c-elf m32r-elf m68hc11-elf m68hc12-elf m68k-elf mcore-elf mep-elf
> > metag-elf microblaze-elf mips-elf moxie-elf msp430-elf mt-elf nios2-elf
> > or1k-elf pj-elf ppc-elf pru-elf riscv-elf rl78-elf rx-elf s12z-elf
> > score-elf sh-elf sparc-elf spu-elf tic6x-elf tilegx-elf tilepro-elf
> > v850-elf visium-elf wasm32-elf xgate-elf xstormy16-elf xtensa-elf
> > z80-elf.
> >
> > The new tests only run for the targets that use the GNU OSABI. From the
> > above list, arm-elf, hppa-elf, msp430-elf, visium-elf do not use the GNU
> > OSABI, so do not support SHF_GNU_RETAIN.
> >
> > Ok to apply?
> >
> > Thanks,
> > Jozef
> 
> +# SHF_GNU_RETAIN requires the GNU OSABI.
> +if { [check_gc_sections_available] && [supports_gnu_osabi] } {
> +    run_ld_link_tests [list \
> + [list "SHF_GNU_RETAIN 1" \
> +     "--gc-sections -e _start --print-gc-sections" "" "" \
> +     {retain1.s} \
> +     {{ ld retain1.msg }} \
> +     "retain1.exe"] \
> + [list "SHF_GNU_RETAIN 3 (keep sections referenced by retained sections)" \
> +     "--gc-sections -e _start --print-gc-sections" "" "" \
> +     {retain3.s} {} \
> +     "retain3.exe"] \
> + [list "SHF_GNU_RETAIN 4 (keep orphaned sections when not discarding)" \
> +     "--gc-sections -e _start --print-gc-sections
> --orphan-handling=place" "" "" \
> +     {retain4.s} {} \
> +     "retain4.exe"] \
> + [list "Build libretain5.a" \
> +     "" "" "" \
> +     {retain5lib.s} {} "libretain5.a"] \
> + [list "SHF_GNU_RETAIN 5 (don't pull SHF_GNU_RETAIN section out of lib)" \
> +     "--gc-sections -e _start --print-gc-sections" "-Ltmpdir -lretain5" "" \
> +     {retain5main.s} {} \
> +     "retain5.exe"] \
> + [list "Build libretain6.a" \
> +     "" "" "" \
> +     {retain6lib.s} {} "libretain6.a"] \
> + [list "SHF_GNU_RETAIN 6 (pull section out of lib required by
> SHF_GNU_RETAIN section)" \
> +     "--gc-sections -e _start --print-gc-sections" "-Ltmpdir -lretain6" "" \
> +     {retain6main.s} \
> +     {{ ld retain6.msg }} \
> +     "retain6.exe"] \
> + ]
> +}
> +
> 
> Can you use *.d files like
> 
> retain6.d:
> #ld: --gc-sections --print-gc-sections -e _start
> #warning_output: retain6.l
> #target: [check_gc_sections_available]
> 
> instead?

Fixed in the attached patch.

Thanks,
Jozef
> 
> -- 
> H.J.