[LLVMdev] Broken PLT on ARM from R183966

[Anton Korobeynikov]

LGTM

On Wed, Aug 21, 2013 at 1:51 PM, Logan Chien <tzuhsiang.chien at gmail.com> wrote:
> 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
>> > >
>> > >
>> > > _______________________________________________
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>> > >
>>
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>
>
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-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University