Re: LTO vs GCC 8

[Freddie Chopin <freddie_chopin@op.pl>]

On Fri, 2018-05-11 at 18:51 +0200, Richard Biener wrote:
> That's an interesting result. Do you have any non-LTO objects?
> Basically I'm curious what ld eliminates that gcc with LTO doesn't. 

Whole project is compiled with LTO, part of the project is provided as
a library (which is archived with arm-none-eabi-gcc-ar). Only non-LTO
stuff in the final executable are objects from standard toolchain
libraries and I suppose they are the culprit here - the toolchain is
compiled with -ffunction-sections -fdata-sections, but without -flto.
Maybe I should actually compile the whole toolchain with -flto -ffat-
lto-objects? Is this a sane idea?

> As to a workaround for the ld bug you can try keeping all .debug_*
> sections. IIRC 2.30 has the bug fixed (on the branch). 

Indeed - "keeping" all the debug sections is a viable alternative. I've
found out that it is enough to "keep" just these:

	/* DWARF 2 */
	.debug_info 0 : { KEEP(*(.debug_info .gnu.linkonce.wi.*)); }
	 ...
	.debug_frame 0 : { KEEP(*(.debug_frame)); }

I have to check whether debugging something like that is actually
possible (; Thanks for the workaround!

Regards,
FCh