Re: [fpc-pascal] question about _fpc_local_unwind

[Sven Barth via fpc-pascal]

Am 02.02.2018 18:12 schrieb "Matias Vara" :

Hello,

2018-02-02 17:17 GMT+01:00 Sven Barth via fpc-pascal <
fpc-pascal@lists.freepascal.org>:

> Am 02.02.2018 15 <02%2002%2020%2018%2015>:50 schrieb "Matias Vara" <
> matiasev...@gmail.com>:
>
> Thanks for the answer, I will imitate in Toro the behavior of Win64.
>
>
> Maybe it wound be better if you try to use the i386-embedded or
> x86_64-embedded targets. The non-embedded targets are simply not geared
> towards usage on a bare platform
>
>
Thanks for the suggestion, I don't think I am able to do that since the
whole kernel  compiles well by using the Win64 target. So I am not planing
to change the target. I notice that the code is in rtl/win64/seh64.inc so I
am starting to try to understand it.

Most of the exception handling and unwinding is done by Windows, relying on
specific sections in the binary. You essentially picked one of the worst
targets to implement your kernel with...
Another plus of the embedded target: you can disable RTL features that you
don't need (e.g. RTTI, threading, etc.).

Regards,
Sven

Regards,
Sven
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Re: [fpc-pascal] question about _fpc_local_unwind

[Matias Vara]

Hello,

2018-02-02 17:17 GMT+01:00 Sven Barth via fpc-pascal <
fpc-pascal@lists.freepascal.org>:

> Am 02.02.2018 15 <02%2002%2020%2018%2015>:50 schrieb "Matias Vara" <
> matiasev...@gmail.com>:
>
> Thanks for the answer, I will imitate in Toro the behavior of Win64.
>
>
> Maybe it wound be better if you try to use the i386-embedded or
> x86_64-embedded targets. The non-embedded targets are simply not geared
> towards usage on a bare platform
>
>
Thanks for the suggestion, I don't think I am able to do that since the
whole kernel  compiles well by using the Win64 target. So I am not planing
to change the target. I notice that the code is in rtl/win64/seh64.inc so I
am starting to try to understand it.

Matias



> Regards,
> Sven
>
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Re: [fpc-pascal] question about _fpc_local_unwind

[Sven Barth via fpc-pascal]

Am 02.02.2018 15:50 schrieb "Matias Vara" :

Thanks for the answer, I will imitate in Toro the behavior of Win64.


Maybe it wound be better if you try to use the i386-embedded or
x86_64-embedded targets. The non-embedded targets are simply not geared
towards usage on a bare platform.

Regards,
Sven
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Re: [fpc-pascal] question about _fpc_local_unwind

[Matias Vara]

Thanks for the answer, I will imitate in Toro the behavior of Win64.

Matias


2018-02-01 20:49 GMT+01:00 Jonas Maebe :

> On 01/02/18 16:24, Matias Vara wrote:
>
>> I partial answered my question by reading https://www.freepascal.org/doc
>> s-html/ref/refse114.html. So I think _fpc_local_unwind() is used to call
>> the finally section when "Exit" is executed in the "Try" section. It is not
>> clear yet what the parameters "frame,target: Pointer" are meant to. I
>> checked the code generated in Linux and is a bit different. It is base on
>> the functions FPC_PUSHEXCEPTADDR and FPC_POPADDRSTACK, which It seems much
>> more clear. Is it possible to generate a similar code in the case of Win64?
>> In other words, is it possible to tell the compiler "generate the
>> 'try-finally-end' block as in Linux"? I don't think so but It is worth to
>> ask.
>>
>
> No, it is not possible. On Win64 the compiler and RTL use so-called
> structured exception handling (SEH), which is required to interoperate with
> code generated by other compilers. See https://msdn.microsoft.com/en-
> us/library/windows/desktop/ms680657(v=vs.85).aspx for more information.
>
>
> Jonas
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Re: [fpc-pascal] question about _fpc_local_unwind

[Jonas Maebe]

On 01/02/18 16:24, Matias Vara wrote:
I partial answered my question by reading 
https://www.freepascal.org/docs-html/ref/refse114.html. So I think 
_fpc_local_unwind() is used to call the finally section when "Exit" is 
executed in the "Try" section. It is not clear yet what the parameters 
"frame,target: Pointer" are meant to. I checked the code generated in 
Linux and is a bit different. It is base on the functions 
FPC_PUSHEXCEPTADDR and FPC_POPADDRSTACK, which It seems much more clear. 
Is it possible to generate a similar code in the case of Win64? In other 
words, is it possible to tell the compiler "generate the 
'try-finally-end' block as in Linux"? I don't think so but It is worth 
to ask.


No, it is not possible. On Win64 the compiler and RTL use so-called 
structured exception handling (SEH), which is required to interoperate 
with code generated by other compilers. See 
https://msdn.microsoft.com/en-us/library/windows/desktop/ms680657(v=vs.85).aspx 
for more information.



Jonas
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Re: [fpc-pascal] question about _fpc_local_unwind

[Matias Vara]

Hello,
I partial answered my question by reading
https://www.freepascal.org/docs-html/ref/refse114.html. So I think
_fpc_local_unwind() is used to call the finally section when "Exit" is
executed in the "Try" section. It is not clear yet what the parameters
"frame,target: Pointer" are meant to. I checked the code generated in Linux
and is a bit different. It is base on the functions FPC_PUSHEXCEPTADDR
and FPC_POPADDRSTACK, which It seems much more clear. Is it possible to
generate a similar code in the case of Win64? In other words, is it
possible to tell the compiler "generate the 'try-finally-end' block as in
Linux"? I don't think so but It is worth to ask.

Thanks, Matias.


2018-01-31 11:17 GMT+01:00 Matias Vara :

> Hello eveyryone,
>
> in my rtl for torokernel, I have to implement "_fpc_local_unwind()"
> however I am not sure about the expected behavior of this function. It
> appers in the code when I use "Exit" inside a "try finally" structure. I
> would like to know what this function should do. So if someone can point me
> to some documetation would be very helpful,
>
> Thanks, Matias.
>
>
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[fpc-pascal] question about _fpc_local_unwind

[Matias Vara]

Hello eveyryone,

in my rtl for torokernel, I have to implement "_fpc_local_unwind()" however
I am not sure about the expected behavior of this function. It appers in
the code when I use "Exit" inside a "try finally" structure. I would like
to know what this function should do. So if someone can point me to some
documetation would be very helpful,

Thanks, Matias.
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