[Vm-dev] Exporting module symbols on windows

[Henrik Sperre Johansen]

On 10.02.2013 13:52, Igor Stasenko wrote:
>   
>
>
> On 10 February 2013 01:51, Eliot Miranda <eliot.miranda at gmail.com> wrote:
>>
>>
>> On Sat, Feb 9, 2013 at 3:18 PM, Igor Stasenko <siguctua at gmail.com> wrote:
>>>
>>> Hi, Eliot
>>>
>>> i thought about it, and i don't like it.
>>> I am in favor of exporting stuff explicitly, rather than implicitly by
>>> compiler..
>>> because with implicit exports, you never know whether given symbol
>>> will be visible or not..
>>> and you have to guess and hope instead of being confident.
>>>
>>> It would be nice if we could have a way to export all functions and variables
>>> which has <api> pragma.. because exporting everything , first is not
>>> needed, second
>>> it will expose some symbols which are really private to VM which is
>>> not very good from design perspective.
>>
>> I agree. All you need to do on WIndows is to collect all the functions that are either marked as api, export: true or in requiredMethodNames and write a .def file.  The syntax of the def file is easy enough (just a list of names IIRC) that a Makefile could munge it to produce a set of flags for a linker (but it's a *lot* of flags :) ).  You might look at where the CodeGenerator produces cointerp.h and cogit.h and add the generation there.
>>
> There's already support for that in codebase
> all we need is to use  __declspec( dllexport )  as recommended in [1].
>
> (btw, it is already used by EXPORT() macro,
> but this macro suitable only for declarations with known return type
> (btw why?), so i took a freedom to add a new)..
>
> - added VM_EXPORT macro
>    in sq.h:
>
> #define VM_EXPORT  /*nothing*/
>
>    in win32/vm/sqPlatformSpecific.h:
>
> #undef VM_EXPORT
> #define VM_EXPORT __declspec( dllexport )
>
> (in both cases right under EXPORT() macro definition)
>
> - changed 3 methods in VMMaker, mainly to emit corresponding macros in
> .headers (see attached)
>
> i wonder, if it is syntactically correct to use
> EXPORT() macro e.g. without parameter.. then VM_EXPORT not needed since
> will be expanded into
> EXPORT(/*nothing*/) =>  __declspec( dllexport ) /*nothing*/
>
>
> And now running in windoze, i  can do:
>
>   NativeBoost loadSymbol: #CFramePointer fromModule: NativeBoost VMModule
> 	 @ 16r5A5710
>
> or:
>   NativeBoost loadSymbol: #suppressHeartbeatFlag fromModule: NativeBoost VMModule
> 	 @ 16r5A56EC
> 	
>
> voila!
>
>
> [1] https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/4/html/Using_ld_the_GNU_Linker/win32.html
>
>
There's also an equivalent in GCC >= 4, in a dll I wrote some time ago I 
used:

#if defined _WIN32 || defined __CYGWIN__
   #define API __declspec(dllexport)
   #define PRIVATE  //Methods not visible by default when compiling 
using CYGWIN or MSVC
#else
   #if __GNUC__ >= 4

     #define API __attribute__ ((visibility("default")))
     #define PRIVATE __attribute__ ((visibility("hidden")))

Used gcc on OSX though, so not sure what the same would be for clang.

Cheers,
Henry

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.squeakfoundation.org/pipermail/vm-dev/attachments/20130211/29688951/attachment.htm