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Re: linker plugin api limitation
- From: Rafael EspÃndola <rafael dot espindola at gmail dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Binutils <binutils at sourceware dot org>, Cary Coutant <ccoutant at gmail dot com>, Evgenii Stepanov <eugeni dot stepanov at gmail dot com>
- Date: Mon, 22 Feb 2016 11:40:12 -0500
- Subject: Re: linker plugin api limitation
- Authentication-results: sourceware.org; auth=none
- References: <CAG3jReJDT2ZDNRh-cYSSBG76FnrReQWbgFgfsA_gvLdb5zmEEw at mail dot gmail dot com> <CAMe9rOqQnyagQ=4BdfkNgPiAzc9X4B0=BNibChyhJfd3osCcmw at mail dot gmail dot com> <CAG3jRe+BBQ-oSU9gu8h26jWZYh1ET03cAunVxsFyUomyC8XJZA at mail dot gmail dot com> <CAMe9rOoRMbnbn+WQ2OYfFDOjqedOQb7z0kcPLpGOAn8RZd01cQ at mail dot gmail dot com>
>> I don't think it is implemented in BFD ld. The idea is that using
>> $ ld ... --start-lib <objs> --end-lib
>> should be equivalent to
>> $ ar rc foo.a <objs>
>> $ ld ... foo.a
>> ar is normally very fast, but when doing a fully distributed build one
>> would still need to copy <objs> to a node just to create foo.a. Using
>> --start-lib/--end-lib saves that step.
> Have you tried the AR equivalent with gold?
I did not, but I am pretty sure what happens: The plugin is never even
asked to look at the member since gold only needs the archive index to
know the member is not used.
The difference with --start-lib/--end-lib is that gold has to use the
plugin to find out the symbols defined by a file to know if it is
needed in the link or not.