[LLVMdev] LLVM IR on different platforms

[Sandeep Kumar Singh]

Hi Andreas,

Thanks for detailed explanation. Now it is very clear to me that I should
write first platform independent code to make it work correct.
As I know, Java is platform independent, will I face the same issue with it?

Thanks and Regards,
Sandeep

On Tue, Jul 7, 2015 at 1:14 PM, Andreas Weber <andreas.c.weber at gmail.com>
wrote:

> Hi Sandeep,
>
> As far as I know, it depends: If you have portable C/C++ source (e.g. with
> ifdefs to handle platform specific stuff) you can compile this source with
> the Linux-defines on Linux to generate a working Linux binary or you can
> compile the same source on Windows with the Windows-defines to generate a
> working Windows binary.
>
> As LLVM/clang is inherently a cross-compiler you can also generate the
> windows object files on Linux when you pass the correct target triple and
> the Windows-defines to your Linux-clang or vice-versa. Note that this will
> only give you object files which you still need to link to obtain a working
> executable (usually with your system linker, link.exe on Windows, ld on
> Linux).
>
> What will not work is compiling the source with a Linux target triple and
> Linux-defines into bitcode and then compile this bitcode into a Windows
> object file and expect it to link and run correctly. The reason is that the
> bitcode already encodes target specific information as it represents
> preprocessed code and was generated to target a specific platform ABI
> defining stuff like name mangeling, struct and vtable layout, exception
> handling, calling convention, etc.
>
> You might get away compiling a Linux-bitcode file into a working Windows
> object file when you restrict yourself to platform independent C (the
> preprocessed source is identical on Windows on Linux) and have only scalar
> values as function parameters but I would not recommend this approach.
>
> Best regards
> Andreas
>
> 2015-07-07 8:13 GMT+02:00 Sandeep Kumar Singh <deepdondo007 at gmail.com>:
>
>> Hi,
>>
>> I am curious to know about LLVM IR as platform independent feature.
>> I have compiler some C and C++ applications that compiled on Linux 64bit
>> machine, now I want to generate bit code file on Windows 64bit machine.
>>
>> 1) Will this execute without any issues?
>> 2) Do I pass any option for making it operating system portable?
>> 3) Can I generate bit code file also on Linux machine and then run on
>> Windows machine?
>>
>> Please give me some pointers?
>>
>> Any help will be highly appreciated.
>>
>>
>> Thanks and Regards,
>> Sandeep
>>
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>>
>


-- 

Thanks and Regards,
Sandeep Kumar Singh
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