On Thu, May 7, 2026 at 2:36 PM Georg-Johann Lay <[email protected]> wrote:
>
> This patch fixes -mno-call-main which did not work with LTO.
>
> Instead of emitting .global __call_main + __call_main=0 in some
> module, it uses a %{mno-call-main: --defsym __call_main=0} spec.
>
> The problem with the old implementation is that avr_no_call_main_p was
> set by cc1[plus] (in avr_insert_attributes) but used by lto1 (in
> avr_file_end).
> The new approach uses --defsym __call_main=0 in order to avoid link
> fails due to multiple definitions of __call_main in *.o and lib<mcu>.a.
In the patch the avr.opt and the avr_insert_attributes hunk shouldn't
be necessary?
That said, even w/o the patch the LTRANS invocations with -flto
should see -mno-call-main, but avr_insert_attributes might not
be called at LTO time. So if in avr_file_end you check
avropt_call_main instead of avr_no_call_main_p you should
get the .global emitted. Of course in every LTRANS object,
but I suppose the linker should merge multiple defs?
> This is for trunk. If you agree, I would also packport it.
>
> Johann
>
> --
>
> AVR: target/125194 - Make -mno-call-main work with -flto.
>
> Instead of emitting .global __call_main + __call_main=0 in some module,
> use a %{mno-call-main: --defsym __call_main=0} spec.
>
> The problem with the old implementation is that avr_no_call_main_p was set
> by cc1[plus] (in avr_insert_attributes) but used by lto1 (in avr_file_end).
> The new approach uses --defsym __call_main=0 in order to avoid link
> fails due to multiple definitions of __call_main in *.o and lib<mcu>.a.
>
> PR target/125194
> gcc/
> * config/avr/avr.cc (avr_no_call_main_p): Remove variable...
> (avr_file_end): ...and code that uses it.
> (avr_insert_attributes): Same. Add "used" to main attributes
> when -mno-call-main.
> * config/avr/avr.opt (-mcall-main): Add Save option flag.
> * config/avr/gen-avr-mmcu-specs.cc (print_mcu): Emit code
> for link_no_call_main specs.
> * config/avr/specs.h (LINK_SPEC): Add %(link_no_call_main).
