[Proposed patch] Huge performance regression in ld -r since binutils >= 2.21

[H.J. Lu]

On Tue, Nov 10, 2015 at 1:17 AM, Alan Modra <amodra@gmail.com> wrote:
> On Tue, Nov 10, 2015 at 12:24:32AM -0800, H.J. Lu wrote:
>> On Mon, Nov 9, 2015 at 10:51 PM, Alan Modra <amodra@gmail.com> wrote:
>> > On Mon, Nov 09, 2015 at 10:04:42AM +0100, Romain Geissler wrote:
>>>> Indeed, much better idea. I will use your patch and apply it to x86/64 as
>> >> well.
>> >
>> > On checking I found I'd made a mistake in the previous patch, so
>> > decided to go with the safer approach of copying relocs at the end of
>> > the loop.  Also, I'm not renaming "rel" to "rrel".
>> >
>> >         * elf64-ppc.c (ppc64_elf_relocate_section): Use read and write
>> >         pointers to reloc array, rather than memmove when deleting a
>> >         reloc.  Don't use RELOC_AGAINST_DISCARDED_SECTION.  Adjust
>> >         reloc counts at end of loop.
>> >         * elf32-ppc.c (ppc_elf_relocate_section): Likewise.
>> >
>>
>> I checked in a similar, but a little different, patch to fix i386 and
>> x86-64.
>
> You deleted a comment line, and need to look at all the "continue"
> statements.  I see one that must copy relocs, and more that should
> copy *or* you should remove the copying code at the end of the loop.
>
> To clarify, I decided to add what is dead code to the powerpc backend
> in case we ever remove relocs when !relocatable.  The only copying
> that is really needed is this one:
>
>       if (bfd_link_relocatable (info))
>         {
>           if (wrel != rel)
>             *wrel = *rel;
>           continue;
>         }

I have checked a patch into x86 backends,

> and you need to add the missing VTINHERIT/VTENTRY copy..
>

Done,

Thanks,

-- 
H.J.