[LLVMdev] Broken PLT on ARM from R183966

[Logan Chien]

Hi,

  I have created a workaround to deal with the PIC function call.  With
this patch, the FastISel will switch back to DAG lowering mechanism if (1)
there is a function call in the basic block and (2) the relocation model is
PIC.  Please have a look.  Hoping the patch will help.

Sincerely,
Logan


On Wed, Aug 21, 2013 at 10:17 AM, Gordon Keiser <gkeiser at arxan.com> wrote:

> Cool, I'll file a bug tomorrow at work and add you to the CC list.
>
> Thanks!
> Gordon Keiser
> Software Development Engineer
> Arxan Technologies
> gkeiser at arxan.com  www.arxan.com
> Protecting the App EconomyT
>
> > -----Original Message-----
> > From: Eric Christopher [mailto:echristo at gmail.com]
> > Sent: Tuesday, August 20, 2013 9:47 PM
> > To: Gordon Keiser
> > Cc: llvmdev at cs.uiuc.edu; JF Bastien
> > Subject: Re: [LLVMdev] Broken PLT on ARM from R183966
> >
> > Filing a bug would be a good start, go ahead and cc me and
> jfb at google.com.
> >
> > Thanks!
> >
> > -eric
> >
> > On Tue, Aug 20, 2013 at 6:10 PM, Gordon Keiser <gkeiser at arxan.com>
> > wrote:
> > > For ARM targets on linux, revision 183966 made Fast ISel default.
> > > Unfortunately, Fast ISel is broken in terms of applying the
> > > ARMII::MO_PLT flags to calls in PIC mode (at least when emitting
> > > assembly);  it never does this.  The normal ISel pass handles this
> > > situation correctly so a temporary local change to disable FastISel
> > > for linux / NaCl targets is working for me right now.
> > >
> > >
> > >
> > > I'm not very familiar with the ISel passes.  I'm guessing the correct
> > > thing to do here would be to apply the attribute correctly in FastISel
> > > so it works, but I'm kind of unfamiliar with this part of the code and
> > > won't have time to dig into it right now, although I'm willing to do
> > > it if someone points me to the right area of code.
> > >
> > >
> > >
> > > In the meantime, would it be worthwhile to submit in a modification to
> > > disable FastISel for non-darwin targets, or is it likely to be fixed
> > > quickly?
> > >
> > >
> > >
> > > -Gordon
> > >
> > >
> > > _______________________________________________
> > > 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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