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, Xi Ruoyao <xry111@xry111.site>
Subject: [PATCH] LoongArch: Allow la.got -> la.pcrel relaxation for shared object
Date: Wed, 6 Dec 2023 03:05:47 +0800 [thread overview]
Message-ID: <20231205190547.52950-1-xry111@xry111.site> (raw)
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;
}
--
2.43.0
next reply other threads:[~2023-12-05 19:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-05 19:05 Xi Ruoyao [this message]
2023-12-15 12:22 ` Ping: " Xi Ruoyao
2023-12-19 7:48 ` mengqinggang
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