Fwd: What is the xawt sizer wrapper, really?

[Artem Ananiev]

Hi, guys,

unfortunately, not many of the current AWT engineers can provide 
valuable information on the wrapper generator. Many thanks to Yuri (in 
CC), he digged up the following bug:

6185483: AMD64: xawt 32-bit build should not require running a 64-bit 
executable

It's hidden on bugs.sun.com, unfortunately.

In a few words, on Solaris, we used to build single rt.jar for both 32- 
and 64-bit platforms, because we couldn't have two rt.jar files in 
solaris-i586 and solaris-amd64. So we had to build rt.jar on 32-bit 
platform, which at that time lacked support for cross-compilation for 
64-bits (Solaris 8, Solaris Studio 8 didn't support 64-bit code 
generation for x86).

Another problem was that when we introduced support for solaris-amd64, 
we followed the same pattern as with solaris-sparc/sparcv9. At the 
promotion time, 32-bit image was copied over 64-bit one - that was fine 
for sparc/sparcv9, as the files were actually the same, but different in 
i586/amd64 case.

Decision was made to calculate 64-bit field offsets in advance and store 
them in the workspace, so we can have 32/64 classes.

There was another discussion a few years ago about the same topic, but I 
don't remember any details. Most likely we decided to leave sizes.64 as 
is...

Given that we now build using SS12, we should check if we can drop 
sizes.64 and calculate 64-bit offsets the same way as we do for 32-bits.

Thanks,

Artem

On 6/14/2012 3:01 PM, Magnus Ihse Bursie wrote:
> On 2012-06-14 12:49, Artem Ananiev wrote:
>>
>>
>> Generation process include creating a new sizer.c file for each
>> structure described in "xlibtypes", compiling it and calling the
>> resulted binary to get offsets for all the structure fields.
>
> How is this supposed to work when cross-compiling?
>
> And why do you need to to this for another platform than the one we are
> compiling for? (E.g., if we are generating a 64-bit macosx build, we
> also do this for 32-bit macosx)
>
>> I don't remember the exact issue about Solaris-x64, why it's handled
>> separately and includes manual generation.
> The information I was able to dig up indicated that the weirdness of how
> this was compiled had caused breakage previously, and this was added as
> some kind of regression test. (It was appearantly designed to catch the
> error of compiling with 64-bit when 32-bit was intended, or vice versa
> -- or something like that).
>> What are exact issues you observe with the wrapper generator?
>
> Portability and cross-compilations issues. The main problem is: why is
> it compiled for anything else than the build platform? If it is supposed
> to just run on the build system, why do we need more than one? And if it
> is supposed to run on the target system (!), then it will not work when
> cross-compiling.
>
> /Magnus