From: Xi Ruoyao <xry111@xry111.site>
To: binutils@sourceware.org
Cc: liuzhensong@loongson.cn, mengqinggang@loongson.cn,
i.swmail@xen0n.name, maskray@google.com, hejinyang@loongson.cn,
cailulu@loongson.cn
Subject: Ping: [PATCH] LoongArch: Allow la.got -> la.pcrel relaxation for shared object
Date: Fri, 15 Dec 2023 20:22:47 +0800 [thread overview]
Message-ID: <5c9d7da55b80be8e6ff11894fcd0c225416859ca.camel@xry111.site> (raw)
In-Reply-To: <20231205190547.52950-1-xry111@xry111.site>
Ping.
On Wed, 2023-12-06 at 03:05 +0800, Xi Ruoyao wrote:
> Even in shared objects, la.got -> la.pcrel relaxation can still be
> performed for symbols with hidden visibility. For example, if a.c is:
>
> extern int x;
> int f() { return x++; }
>
> and b.c is:
>
> int x = 114514;
>
> If compiling and linking with:
>
> gcc -shared -fPIC -O2 -fvisibility=hidden a.c b.c
>
> Then the la.got in a.o should be relaxed to la.pcrel, and the resulted f
> should be like:
>
> pcaddi $t0, x
> ldptr.w $a0, $t0, 0
> addi.w $t1, $a0, 1
> stptr.w $t1, $t0, 0
> ret
>
> Remove bfd_link_executable from the condition of la.got -> la.pcrel
> relaxation so this will really happen. The SYMBOL_REFERENCES_LOCAL
> check is enough not to wrongly relax preemptable symbols (for e.g.
> when -fvisibility=hidden is not used).
>
> Note that on x86_64 this is also relaxed and the produced code is like:
>
> lea x(%rip), %rdx
> mov (%rdx), %rax
> lea 1(%rax), %ecx
> mov %ecx, (%rdx)
> ret
>
> Tested by running ld test suite, bootstrapping and regtesting GCC with
> the patched ld, and building and testing Glibc with the patched ld. No
> regression is observed.
>
> Signed-off-by: Xi Ruoyao <xry111@xry111.site>
> ---
> bfd/elfnn-loongarch.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
> index 024c5d4cd96..80739b817ab 100644
> --- a/bfd/elfnn-loongarch.c
> +++ b/bfd/elfnn-loongarch.c
> @@ -3986,8 +3986,7 @@ loongarch_elf_relax_section (bfd *abfd, asection *sec,
> else
> continue;
>
> - if (h && bfd_link_executable (info)
> - && SYMBOL_REFERENCES_LOCAL (info, h))
> + if (h && SYMBOL_REFERENCES_LOCAL (info, h))
> local_got = true;
> symtype = h->type;
> }
--
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University
next prev parent reply other threads:[~2023-12-15 12:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-05 19:05 Xi Ruoyao
2023-12-15 12:22 ` Xi Ruoyao [this message]
2023-12-19 7:48 ` Ping: " mengqinggang
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