[llvm-dev] Should we switch to --hash-style=both by default in LLD ?

[Rui Ueyama via llvm-dev]

To wrap up, looks like this is what we should do:

 - Use -hash-style=both as a default except MIPS.
 - For MIPS, use -hash-style=sysv as a default.

We'll make a change accordingly.

On Mon, Oct 2, 2017 at 4:22 PM, Rui Ueyama <ruiu at google.com> wrote:

> On Mon, Oct 2, 2017 at 4:15 PM, Rafael Avila de Espindola <
> rafael.espindola at gmail.com> wrote:
>
>> I don't think there is much value in being different from the gnu
>> linkers in here since the common case is to have the compiler driver
>> pass an explicit option.
>>
>> So +1 to changing the default to "both".
>>
>
> ... except for MIPS, as the way how we need to sort .gnu.hash section
> contents is not compatible with a MIPS ABI requirement.
>
> Cheers,
>> Rafael
>>
>> George Rimar <grimar at accesssoftek.com> writes:
>>
>> > Hi !
>> >
>> > During linking LLD and other linkers builds a static hash table for
>> dynamic symbols,
>> > so that in runtime dynamic linker can use this table and find symbols
>> faster.
>> >
>> > --hash-style=style linker option is used to select the hash type:
>> > "Set the type of linker's hash table(s). style can be either "sysv" for
>> classic ELF ".hash" section,
>> > "gnu" for new style GNU ".gnu.hash" section or "both" for both the
>> classic ELF ".hash" and new
>> > style GNU ".gnu.hash" hash tables. The default is "sysv"."
>> >
>> > GNU_HASH format is a better version of hash table (
>> https://sourceware.org/ml/binutils/2006-10/msg00377.html).
>> >
>> > We have --hash-style=sysv currently set by default in LLD.
>> > Though recently (see https://bugs.llvm.org//show_bug.cgi?id=34712) GNU
>> linkers switched to use
>> > ".gnu.hash" section format in addition to normally used classic ".hash".
>> > So they defaults --hash-style to "both" and this looks to be released
>> with binutils 2.30.
>> >
>> > I think we can switch LLD either to "both" or probably to "gnu" by
>> default as well.
>> > Initial version of patch that changes default to "both" is here: D38407
>> >
>> > Any thoughts ?
>> >
>> > Best regards,
>> > George | Developer | Access Softek, Inc
>>
>
>
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