Date: Thu, 8 May 2014 08:11:26 +0300 From: Timo Teras <timo.teras@....fi> To: musl@...ts.openwall.com Cc: dalias@...c.org, scjthm@...e.com Subject: Re: Linking musl with ld.gold On Wed, 7 May 2014 21:06:05 -0400 Rich Felker <dalias@...c.org> wrote: > On Wed, May 07, 2014 at 01:04:43PM +0300, Timo Teras wrote: > > Is perhaps -ffunction-sections and/or -fdata-sections added > > automatically? Those would break musl like experienced. > > They should not break musl; if they do, it's a compiler bug. The > strong symbol that overrides the weak symbol elsewhere is not unused > and available for garbage collection because it's referenced. > > I suspect your claim is just wrong, since IIRC people have > successfully used these options with musl. -fdata-sections breaks things to my understanding. stdin.c (and others), have: FILE *const stdin = &f; FILE *const __stdin_used = &f; And __stdin_used is only ever referenced via weak alias. -fdata-section makes each symbol go to different section, and if linker has gc-sections, it'll remove any unreferenced section. This means __stdin_used will never get pulled in causing problems like described in the original mail. With -ffunction-sections/-fdata-sections/-Wl,--gc-sections it is no longer valid assumption that if compilation unit gets pulled in, all of the symbols defined in it will get pulled in. Of course this does not affect .so as visible exported symbols are reachable and not GCd. But static build would be effected. - Timo
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