llvm dev - Feb 2015 - [LLVMdev] How to specify displacement range of a target instruction to llc

Hi,

I'm working on a project that use llvm openrisc beckend (currently not part
of the upstream). Right now I'm looking at a bug where llc generates memory
instructions that has out-of-range displacement, for example

l.sb 37668(r1), r2    in which 37668 is a 17 bit signed integer, but the
instruction only allows 16 bit signed displacement. As a result, after
running through the assembler, 37668 is encoded wrongly into -27668 because
it's being sign extended.

Can someone point to me where should I add code to do the check, any API I
can use ?

Thanks,
Patrick
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Any help ???

2015-02-18 13:43 GMT-05:00 Ziqiang Patrick Huang <
ziqiang.huang1001 at gmail.com>:
> Hi,
>
> I'm working on a project that use llvm openrisc beckend (currently not
> part of the upstream). Right now I'm looking at a bug where llc
generates
> memory instructions that has out-of-range displacement, for example
>
> l.sb 37668(r1), r2    in which 37668 is a 17 bit signed integer, but the
> instruction only allows 16 bit signed displacement. As a result, after
> running through the assembler, 37668 is encoded wrongly into -27668 because
> it's being sign extended.
>
> Can someone point to me where should I add code to do the check, any API I
> can use ?
>
> Thanks,
> Patrick
>


-- 
*Ziqiang Huang*
*Electrical and Computer Engineering*
*Hudson 213c, Duke University*
*Tel: 919-491-3677*
*Email: ziqiang.huang at duke.edu <ziqiang.huang at duke.edu>*
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You'd need to ask the authors of this backend, not here.

On Thu, Feb 19, 2015 at 7:48 PM, Ziqiang Patrick Huang
<ziqiang.huang1001 at gmail.com> wrote:
> Any help ???
>
> 2015-02-18 13:43 GMT-05:00 Ziqiang Patrick Huang
> <ziqiang.huang1001 at gmail.com>:
>
>> Hi,
>>
>> I'm working on a project that use llvm openrisc beckend (currently
not
>> part of the upstream). Right now I'm looking at a bug where llc
generates
>> memory instructions that has out-of-range displacement, for example
>>
>> l.sb 37668(r1), r2    in which 37668 is a 17 bit signed integer, but
the
>> instruction only allows 16 bit signed displacement. As a result, after
>> running through the assembler, 37668 is encoded wrongly into -27668
because
>> it's being sign extended.
>>
>> Can someone point to me where should I add code to do the check, any
API I
>> can use ?
>>
>> Thanks,
>> Patrick
>
>
>
>
> --
> Ziqiang Huang
> Electrical and Computer Engineering
> Hudson 213c, Duke University
> Tel: 919-491-3677
> Email: ziqiang.huang at duke.edu
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>


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