[Bug rtl-optimization/67532] Add -fno-plt=file and -fno-plt=[symbol,...]

[tmsriram at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67532

--- Comment #1 from Sriraman Tallam <tmsriram at google dot com> ---
On Wed, Sep 9, 2015 at 3:24 PM, hjl.tools at gmail dot com <
gcc-bugzilla@gcc.gnu.org> wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67532
>
>             Bug ID: 67532
>            Summary: Add -fno-plt=file and -fno-plt=[symbol,...]
>            Product: gcc
>            Version: 6.0
>             Status: UNCONFIRMED
>           Severity: normal
>           Priority: P3
>          Component: rtl-optimization
>           Assignee: unassigned at gcc dot gnu.org
>           Reporter: hjl.tools at gmail dot com
>                 CC: tmsriram at google dot com
>   Target Milestone: ---
>
> Drawbacks with -fno-plt and noplt attribute are
>
> 1. -fno-plt may force locally defined functions to be called via
> their GOT slots through indirect branch, instead of direct branch.
> 2. noplt attribute doesn't work on libcalls of builtin functions.
>

I am being bitten by this and want to fix it.  I am working on a patch.


> 3. noplt attribute requires modifying source codes which may not
> be desirable for third party source packages.
>
> We can add -fno-plt=file and -fno-plt=[symbol,...] options to specify
> which external functions should be called via their GOT slots to avoid
> PLT.
>

Yes, I second this idea and I proposed doing -fno-plt=symbol originally but
was shot down because it was felt using mangled symbols on command line is
not desirable. This should be helpful however.

Thanks
Sri


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