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[Bug rtl-optimization/67532] Add -fno-plt=file and -fno-plt=[symbol,...]
- From: "tmsriram at google dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 09 Sep 2015 22:30:50 +0000
- Subject: [Bug rtl-optimization/67532] Add -fno-plt=file and -fno-plt=[symbol,...]
- Auto-submitted: auto-generated
- References: <bug-67532-4 at http dot gcc dot gnu dot org/bugzilla/>
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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