Re: [PATCH 3/3] LoongArch: Reword message for unresolvable PC-relative relocs

[Lulu Cai <cailulu@loongson.cn>]

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On 12/13/24 1:53 PM, Xi Ruoyao wrote:
> If we hit such a bad reloc, it means the programmer has somehow wrongly
> instructed the compiler to generate PC-relative relocs against external
> symbols.  "Recompiling with -fPIC" (or -fPIE) is just misleading.
>
> Signed-off-by: Xi Ruoyao <xry111@xry111.site>
> ---
>   bfd/elfnn-loongarch.c                                     | 4 ++++
>   ld/testsuite/ld-loongarch-elf/bad_pcala_hi20_global.d     | 2 +-
>   ld/testsuite/ld-loongarch-elf/bad_pcala_hi20_global_pie.d | 2 +-
>   ld/testsuite/ld-loongarch-elf/bad_pcala_hi20_weak.d       | 2 +-
>   ld/testsuite/ld-loongarch-elf/bad_pcala_hi20_weak_pie.d   | 2 +-
>   ld/testsuite/ld-loongarch-elf/bad_pcrel20_s2_global.d     | 2 +-
>   ld/testsuite/ld-loongarch-elf/bad_pcrel20_s2_weak.d       | 2 +-
>   7 files changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
> index 5d252bcccb9..93368275b46 100644
> --- a/bfd/elfnn-loongarch.c
> +++ b/bfd/elfnn-loongarch.c
> @@ -894,6 +894,10 @@ bad_static_reloc (struct bfd_link_info *info,
>         pic = _("; recompile with -fPIE");
>       }
>   
> +  if (r_type == R_LARCH_PCREL20_S2 || r_type == R_LARCH_PCALA_HI20)
> +    pic = _("; recompile with -mno-direct-extern-access and check the "
> +	    "symbol visibility");
> +
>     (*_bfd_error_handler)
>      (_("%pB:(%pA+%#lx): relocation %s against `%s` can not be used when making "
>         "%s%s"),

Perhaps the prompt here is not always appropriate. such as:
$ cat test.c

int a =1;
int main (void)
{
printf("%d\n",a);
}

$ gcc -fno-pic -c test.o
$ gcc -shared -o test test.o

Will get error message:
ld: test.o:(.text+0x10): relocation R_LARCH_PCALA_HI20 against `a` can 
not be used when making a shared object; recompile
with -mno-direct-extern-access and check the symbol visibility

If the user follows the prompts and uses "gcc -mno-direct-extern-access 
-c test.o" to compile and then link, an error will still be reported.
However, the problem is solved after recompiling and linking using "gcc 
-fpic -c test.o".

> diff --git a/ld/testsuite/ld-loongarch-elf/bad_pcala_hi20_global.d b/ld/testsuite/ld-loongarch-elf/bad_pcala_hi20_global.d
> index 6ecefd1d48a..fac02d036ba 100644
> --- a/ld/testsuite/ld-loongarch-elf/bad_pcala_hi20_global.d
> +++ b/ld/testsuite/ld-loongarch-elf/bad_pcala_hi20_global.d
> @@ -2,4 +2,4 @@
>   #source: bad_pcala_hi20_global.s
>   #target: [check_shared_lib_support]
>   #ld: -shared --defsym global_a=0x10 --defsym global_b=0x20
> -#error: .*: relocation R_LARCH_PCALA_HI20 against `global_b` can not be used when making a shared object; recompile with -fPIC
> +#error: .*: relocation R_LARCH_PCALA_HI20 against `global_b` can not be used when making a shared object; recompile with -mno-direct-extern-access and check the symbol visibility