From: Fangrui Song <i@maskray.me>
To: Alan Modra <amodra@gmail.com>
Cc: Tatsuyuki Ishi <ishitatsuyuki@gmail.com>, binutils@sourceware.org
Subject: Re: [PATCH 0/4] gas: Add support for LLVM addrsig and addrsig_sym.
Date: Wed, 25 May 2022 00:59:49 -0700 [thread overview]
Message-ID: <DS7PR12MB57651E20FBD3D8859C53E38ECBD69@DS7PR12MB5765.namprd12.prod.outlook.com> (raw)
In-Reply-To: <Yo3cGWMfe92mIU2n@squeak.grove.modra.org>
On Wed, May 25, 2022 at 12:34 AM Alan Modra <amodra@gmail.com> wrote:
>
> On Wed, May 25, 2022 at 12:19:24AM -0700, Fangrui Song wrote:
> > I have to be fair, the design of SHT_LLVM_ADDRSIG has a major problem
> > that it does not work with objcopy and ld -r:
>
> So, discard the section on ld -r and objcopy if symbols change?
In llvm-project, llvm-objcopy does not recognize/discard SHT_LLVM_ADDRSIG.
Both GNU objcopy and llvm-objcopy will set sh_link to 0 for the
unrecognized section.
ld.lld --icf=safe prints a warning [1] for SHT_LLVM_ADDRSIG when
sh_link==0 (--icf=all does not need SHT_LLVM_ADDRSIG).
The users I need to serve use -Wl,--fatal-warnings to convert warnings
to errors, so we need to do `objcopy --remove-section=.llvm_addrsig`
in a few places.
objcopy discarding SHT_LLVM_ADDRSIG would be more ergonomic, but it
raises a question whether it is better for the user to be aware of the
problem and discard the section by themselves.
[1]: https://github.com/llvm/llvm-project/blob/main/lld/test/ELF/icf-safe.s#L92
next prev parent reply other threads:[~2022-05-25 8:07 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-25 6:42 Tatsuyuki Ishi
2022-05-25 6:42 ` [PATCH 1/4] elf: Add definition for SHT_LLVM_ADDRSIG Tatsuyuki Ishi
2022-05-26 10:03 ` Jan Beulich
2022-05-26 10:13 ` Tatsuyuki Ishi
2022-05-26 10:19 ` Jan Beulich
2022-05-26 10:36 ` Tatsuyuki Ishi
2022-05-27 17:28 ` Peter Collingbourne
2022-05-25 6:42 ` [PATCH 2/4] gas: Add support for LLVM addrsig and addrsig_sym directives on ELF Tatsuyuki Ishi
2022-05-25 7:23 ` Alan Modra
2022-05-25 7:49 ` Jan Beulich
2022-05-25 7:58 ` Tatsuyuki Ishi
2022-05-25 8:07 ` Fangrui Song
2022-05-25 8:34 ` Jan Beulich
2022-05-25 8:41 ` Tatsuyuki Ishi
2022-05-25 6:42 ` [PATCH 3/4] bfd: Output SH_LINK to .symtab for SHT_LLVM_ADDRSIG Tatsuyuki Ishi
2022-05-25 7:46 ` Jan Beulich
2022-05-25 6:42 ` [PATCH 4/4] gas: Add basic test for addrsig Tatsuyuki Ishi
2022-05-25 7:30 ` Alan Modra
2022-05-25 7:19 ` [PATCH 0/4] gas: Add support for LLVM addrsig and addrsig_sym Fangrui Song
2022-05-25 7:34 ` Alan Modra
2022-05-25 7:59 ` Fangrui Song [this message]
2022-05-25 8:01 ` Tatsuyuki Ishi
2022-05-25 6:46 Tatsuyuki Ishi
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