LTO vs. default section alignment vs. relocatable links.

[H.J. Lu]

On Tue, Feb 1, 2011 at 1:44 PM, Dave Korn <dave.korn.cygwin@gmail.com> wrote:
>
>    Hi all,
>
>  LTO IR sections need to have 1-byte alignment, and that is how we get them
> from GAS.  So far so good, but when we do a -r link of two object files, the
> placement of the LTO sections is handle by orphan handling, since there aren't
> any LTO section output statements in any of the default linker scripts (yet).
>
>  In practice, this leads (at least on i686-pc-cygwin) to the sections being
> placed after .rodata, and they get the default section alignment.  That causes
> their sizes to be rounded up to 4 with padding, which fatally confuses the
> zlib decompressor in lto1 when we come to stream them back in later.
>
>  Rather than modifying all the default linker scripts, can we handle this by
> creating a synthetic output statement of some kind at LD start-up?  Or should
> this be considered a weakness of orphan placement; should it notice the
> alignment of the input section and create a similarly aligned orphan output
> section?

It isn't a problem on Linux. Is this a cygwin specific problem?


-- 
H.J.