From: Rich Felker <dalias@libc.org>
To: Jiahao XU <Jiahao_XU@outlook.com>
Cc: "musl@lists.openwall.com" <musl@lists.openwall.com>
Subject: Re: [musl] Can’t build musl with lto=thin
Date: Sat, 30 Jan 2021 15:12:31 -0500 [thread overview]
Message-ID: <20210130201227.GP23432@brightrain.aerifal.cx> (raw)
In-Reply-To: <SYBP282MB0202FA24200DAEBF962C59088AB99@SYBP282MB0202.AUSP282.PROD.OUTLOOK.COM>
On Fri, Jan 29, 2021 at 12:19:42PM +0000, Jiahao XU wrote:
> musl-1.2.2 compilation with clang-11 failed to build libc.so at the final linking stage:
>
> ld.lld: error: undefined hidden symbol: __dls2
> >>> referenced by ld-temp.o
> >>> lto.tmp:(_dlstart_c)
> >>> did you mean: __dls3
> >>> defined in: lto.tmp
>
> I am using CFLAGS=‘-march=native -mtune=native -Oz -flto
> -fmerge-all-constants -fomit-frame-pointer’ and LDFLAGS=‘-flto
^^^^^^^^^^^^^^^^^^^^^
The -fmerge-all-constants option gives non-conforming language
semantics and should not be used, but that's a separate issue.
> -fuse-ld=lld -Wl,—plugin-opt=O3,-O3,—icf=safe’.
> No configure option is supplied.
Otherwise, it's a known issue that LTO misses references from asm
(both top-level and in functions). I think dlstart.lo and a few other
files should just be built with LTO disabled; any LTO-type
optimization in code that runs at this stage is inherently invalid,
anyway. So something like (in config.mak):
obj/ldso/dlstart.lo: CFLAGS_ALL += -fno-lto
Rich
next prev parent reply other threads:[~2021-01-30 20:12 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-29 12:19 Jiahao XU
2021-01-29 20:04 ` Szabolcs Nagy
2021-01-29 20:53 ` Fangrui Song
2021-01-30 20:12 ` Rich Felker [this message]
2021-01-30 20:59 ` Леонид Юрьев (Leonid Yuriev)
[not found] ` <SYBP282MB020277E08EB49C9AC9BF90888AB89@SYBP282MB0202.AUSP282.PROD.OUTLOOK.COM>
2021-01-30 23:30 ` Rich Felker
[not found] ` <SYBP282MB0202BF16DD08A2F1537FD5428AB89@SYBP282MB0202.AUSP282.PROD.OUTLOOK.COM>
2021-01-31 5:01 ` Rich Felker
2021-01-31 5:32 ` Jiahao XU
2021-01-31 21:01 ` Rich Felker
2021-01-31 22:29 ` Jiahao XU
2021-02-01 0:22 ` Jiahao XU
2021-02-01 0:31 ` Jiahao XU
2021-02-01 0:44 ` Jiahao XU
2021-02-01 0:50 ` Jiahao XU
2021-02-01 13:20 ` Jiahao XU
2021-02-01 16:55 ` Nick Bray
2021-02-01 17:53 ` Rich Felker
2021-02-01 18:06 ` Fangrui Song
2021-02-01 21:20 ` Jiahao XU
2021-02-13 17:54 ` Tim Tassonis
2021-02-14 5:59 ` Markus Wichmann
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