[LLVMdev] Code generation support in llvm for windows phone

Sun Jun 8 00:38:24 PDT 2014

Wow ... I did a git pull on llvm and clang compiled my c file
clang  -target thumbv7-windows -c  -O0  a.c -oa.obj
dumpbin /all on a.obj now shows "thumb instructions" ..... I'll try running
this tomorrow and post back.

Regards,
Kashyap

On Sun, Jun 8, 2014 at 9:39 AM, Saleem Abdulrasool <compnerd at compnerd.org>
wrote:

> On Sat, Jun 7, 2014 at 8:03 PM, C K Kashyap <ckkashyap at gmail.com> wrote:
>
>> Thank you so much Saleem,
>> The target is Windows phone 8.1 (ARM). I'll update the crash details
>> tomorrow.
>>
>
> Please rebuild the tree after SVN r210415 when you test it again.  It
> seems that link.exe needs the IMAGE_SCN_MEM_16BIT set in order to select
> the function as a thumb function rather than silently assuming that all
> functions are thumb (which was something that I suspected but hadn't tested
> since I haven't been using that linker for my testing).
>
> If you were seeing an "Invalid Instruction" exception, that was caused by
> the application switching into ARM mode execution (rather than staying in
> thumb mode as it should).
>
> Please let met know what the result is with your test, as I do want to
> ensure that this does play well with the Visual Studio toolchain.
>
> One big problem is that I have to use a physical windows phone for
>> execution.
>>
> I wonder if it is possible to execute such "exes" using qemu.
>>
>
> Please let me know if you get that to work somehow (I don't know if there
> is a way to do that currently).
>
>
>> Regards,
>> Kashyap
>>
>>
>>
>> On Sun, Jun 8, 2014 at 2:53 AM, Saleem Abdulrasool <compnerd at compnerd.org
>> > wrote:
>>
>>> On Sat, Jun 7, 2014 at 10:06 AM, C K Kashyap <ckkashyap at gmail.com>
>>> wrote:
>>>
>>>> Hi Saleem,
>>>> I have a similar situation - I'd appreciate your inputs on it. I
>>>> noticed that the obj file generated using llvm does not contain "thumb"
>>>> instructions. I suspect that is what is causing runtime crash for me.
>>>>
>>>>
>>>> Here's what I've tried -
>>>> Start with a.c (on my linux machine where I have llvm/clang built as of
>>>> yesterday)
>>>>                       int add(int i, int j) {int k = i + j; return k; }
>>>> clang  -S  -O0  a.c
>>>>
>>>
>>> This targets the default target, which may not necessarily be the target
>>> that you want.
>>>
>>>
>>>> llc -filetype=obj -mtriple=thumbv7-windows -O0 a.ll
>>>>
>>>
>>> This is a bit round-about to generate the object-file.
>>>
>>> You can actually generate the object file directly from clang at this
>>> point, which may not have been the case when you first started looking at
>>> this.
>>>
>>> $ clang -target armv7-windows -c a.c -o a.obj
>>>
>>> If you look at the generated assembly, you will find that it will
>>> generate a thumb function, even though the object file may be missing the
>>> appropriate flag in the case of the public llvm repository (Ill look into
>>> that btw).
>>>
>>> I get a.obj from the above steps.
>>>>
>>>> I take this a.obj over to my windows 8.1 machine where I have VS2013
>>>> update 2 installed
>>>>
>>>> I open up a command window and run
>>>> C:\Users\kck\arm>"c:\Program Files (x86)\Microsoft Visual Studio
>>>> 12.0\vc\bin\x86_arm\vcvarsx86_arm.bat"
>>>>
>>>> I create a file file m.c
>>>> int main() { return add(20,30);}
>>>>
>>>
>>> This might cause an issue.  You are not providing a declaration for the
>>> symbol.  If cl ends up converting it to a dllimport'ed symbol, the
>>> generated application will not execute.
>>>
>>>
>>>> I build the whole thing like this -
>>>>
>>>> cl m.c a.obj
>>>>
>>>
>>> That seems right; I will note that all my testing with cl has been with
>>> /MD.
>>>
>>>
>>>> Things seem  to work fine and m.exe gets generated.
>>>>
>>>> However I noticed a difference in the dumpbin output for a.obj and
>>>> m.obj - In m.obj, I can see "Thumb instructions" where as in a.obj, I don't
>>>> see that.
>>>>
>>>
>>> I'll look into that, but, I suspect that this is not the cause of the
>>> crash.
>>>
>>>
>>>> I'd appreciate any pointers on this.
>>>>
>>>
>>> Can you specify what the target environment is?  (Device, Windows
>>> version, etc).
>>>
>>> Actual details of the crash may also be relevant.  Also of interest
>>> would be how you are loading the generated binary onto the device.  The
>>> only way that I know of accomplishing that involves the use of Visual
>>> Studio's remote debugging functionality.
>>>
>>>
>>>> Regards,
>>>> Kashyap
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Fri, May 30, 2014 at 10:45 PM, Saleem Abdulrasool <abdulras at fb.com>
>>>> wrote:
>>>>
>>>>>
>>>>> On May 28, 2014, at 5:18 AM, Rajat Mahajan <rmahajan at adobe.com> wrote:
>>>>>
>>>>> > I am talking about Windows Mobile 8 and 8.1 and not CE.
>>>>> > Not sure though that the Windows 8 (ARM NT) is similar to Windows
>>>>> Mobile 8 platform.
>>>>> >
>>>>> > I used the following command to generate the obj file
>>>>> >    Llc.exe -mtriple=thumbv7-windows  -filetype=obj  <some_name>.bc
>>>>> >
>>>>> > The object file generated in the above object doesn't get linked
>>>>> when I try to link it with the windows mobile library as it fails to
>>>>> recognize the object format.  ( Not a valid object file )
>>>>> >
>>>>> > Hope I am clear.
>>>>>
>>>>> Unfortunately, you have merely repeated your previous statement.  I
>>>>> don’t have enough here to diagnose nor even speculate what is going on.
>>>>>
>>>>> If you can provide the object file, it would be helpful as I am unable
>>>>> to reproduce this issue.  Although, I ran it via clang, I see no reason
>>>>> that the output would be different as the backend is the same.
>>>>>
>>>>> The triple is certainly correct (particularly for llc, clang will
>>>>> treat armv7-windows as thumbv7-windows).  How did you generate the bit
>>>>> code?  My testing has usually started from C or LLVM IR rather than bit
>>>>> code, but, I suspect that shouldn’t be a real issue.
>>>>>
>>>>> With the given information, the only thing that comes to mind is that
>>>>> your environment is setup improperly, resulting in the wrong link.exe being
>>>>> invoked.
>>>>>
>>>>> > ~rajat
>>>>> >
>>>>> > -----Original Message-----
>>>>> > From: Saleem Abdulrasool [mailto:abdulras at fb.com]
>>>>> > Sent: Friday, May 16, 2014 11:23 PM
>>>>> > To: Rajat Mahajan
>>>>> > Cc: llvmdev at cs.uiuc.edu
>>>>> > Subject: Re: [LLVMdev] Code generation support in llvm for windows
>>>>> phone
>>>>> >
>>>>> >
>>>>> > On May 16, 2014, at 6:53 AM, Rajat Mahajan <rmahajan at adobe.com>
>>>>> wrote:
>>>>> >
>>>>> >> Hi,
>>>>> >>
>>>>> >> Is there support available in llc to convert llvm bytecode to
>>>>> Windows Mobile binary?
>>>>> >> I have tried triples like arm-pc-win32 , thumbv7-window ... but the
>>>>> object file generated is not getting linked to the windows native project.
>>>>> >> Any pointers will be greatly appreciated?
>>>>> >
>>>>> > As Reid mentioned, I have been working on this recently.  Just to
>>>>> make sure that we are talking about the same environment, I assume that you
>>>>> are talking about Windows 8 (ARM NT) rather than the Windows CE based
>>>>> environment.
>>>>> >
>>>>> > Can you please explain what exactly you mean by "the object file
>>>>> generated is not getting linked to the windows native project".  The object
>>>>> file that we generate should be pretty compatible with MSVC.  If you have
>>>>> specific cases where we are generating something that is incompatible, I
>>>>> would be quite interested in hearing about that.
>>>>> >
>>>>> >> Thanks,
>>>>> >> ~rajat
>>>>> >> _______________________________________________
>>>>> >> LLVM Developers mailing list
>>>>> >> LLVMdev at cs.uiuc.edu
>>>>> https://urldefense.proofpoint.com/v1/url?u=http://llvm.cs.uiuc.edu/&k=ZVNjlDMF0FElm4dQtryO4A%3D%3D%0A&r=CchYc4lrV44%2BZqxZADw0BQ%3D%3D%0A&m=4sS%2FRJsOxjeRZpxwDsr85CHzLMrTV5IeD%2Bf2OnxlCFY%3D%0A&s=64253b311de373a46904eada51eb8c9f732f8f65d14f0551223b2a7c769f135a
>>>>> >>
>>>>> https://urldefense.proofpoint.com/v1/url?u=http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev&k=ZVNjlDMF0FElm4dQtryO4A%3D%3D%0A&r=CchYc4lrV44%2BZqxZADw0BQ%3D%3D%0A&m=4sS%2FRJsOxjeRZpxwDsr85CHzLMrTV5IeD%2Bf2OnxlCFY%3D%0A&s=5c75919fb4cc3458c6e733d0d672d937dca015122c56ab7b826bc6b5ae74a594
>>>>> >
>>>>> > --
>>>>> > Saleem Abdulrasool
>>>>> > abdulras (at) fb (dot) com
>>>>> >
>>>>> >
>>>>> >
>>>>> >
>>>>> >
>>>>>
>>>>> --
>>>>> Saleem Abdulrasool
>>>>> abdulras (at) fb (dot) com
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> LLVM Developers mailing list
>>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>
>>>>
>>>
>>>
>>> --
>>> Saleem Abdulrasool
>>> compnerd (at) compnerd (dot) org
>>>
>>
>>
>
>
> --
> Saleem Abdulrasool
> compnerd (at) compnerd (dot) org
>
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