llvm dev - Mar 2009 - [LLVMdev] Question about llvm/llvm-gcc visibility

Gurus-

Do llvm/llvm-gcc support pragma definitions for visibility like:

#pragma GCC visibility push(hidden)

If so, what are the options I need to set when configuring llvm and
llvm-gcc?

I'm able to compile the module with llvm-gcc (with the above pragma
included), but the kernel still rejects the module at load time saying the
module is compiled with PLT/GOT.

Any Inputs, Insights?

Thanks in advance,
-KC
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Hi, Mark
> #pragma GCC visibility push(hidden)
In theory - yes.
> If so, what are the options I need to set when configuring llvm and
> llvm-gcc?
Well... No extra options are needed.
> I'm able to compile the module with llvm-gcc (with the above pragma
> included), but the kernel still rejects the module at load time saying the
> module is compiled with PLT/GOT.
Visibility != w/o PLT/GOT, it only reduces calls / accesses via PLT/GOT.
> Any Inputs, Insights?
Please consider filling a PR in llvm bugzilla with sources in question
and/or generated LLVM IR (you can grab it supplying -emit-llvm option
to llvm-gcc)

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University

On Thu, Mar 19, 2009 at 1:46 AM, Anton Korobeynikov <anton at
korobeynikov.info
> wrote:
> Hi, Mark
>
> > #pragma GCC visibility push(hidden)
> In theory - yes.
>
> > If so, what are the options I need to set when configuring llvm and
> > llvm-gcc?
> Well... No extra options are needed.
>
> > I'm able to compile the module with llvm-gcc (with the above
pragma
> > included), but the kernel still rejects the module at load time saying
> the
> > module is compiled with PLT/GOT.
> Visibility != w/o PLT/GOT, it only reduces calls / accesses via PLT/GOT.

I agree, though initially I thought otherwise.

The symbol in question here is a memcpy (introduced by the compiler probably
at codegen) for a "big" copy. The memcpy thus introduced is somehow of
type
R_X86_64_PLT32 instead of it being a R_X86_64_PC32. Without the "bad"
memcpy, things seem to work, the module loads and works.

I'll investigate some more and then file a PR. Thanks for your help!

-KC

> > Any Inputs, Insights?
> Please consider filling a PR in llvm bugzilla with sources in question
> and/or generated LLVM IR (you can grab it supplying -emit-llvm option
> to llvm-gcc)
>
> --
> With best regards, Anton Korobeynikov
> Faculty of Mathematics and Mechanics, Saint Petersburg State University
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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