llvm dev - Jan 2016 - r250501 adds dependancy to ole32.dll on MSVC

On Wed, Dec 23, 2015 at 9:38 PM, Aaron Ballman <aaron at aaronballman.com>
wrote:
> On Wed, Dec 23, 2015 at 3:28 PM, Reid Kleckner <rnk at google.com>
wrote:
>> On Wed, Dec 23, 2015 at 11:25 AM, Aaron Ballman via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>>>
>>> On Wed, Dec 23, 2015 at 1:55 PM, Jakob Bornecrantz <wallbraker
at gmail.com>
>>> wrote:
>>> > On Wed, Dec 23, 2015 at 5:49 PM, Aaron Ballman <aaron at
aaronballman.com>
>>> > wrote:
>>> >> On Wed, Dec 23, 2015 at 11:29 AM, Jakob Bornecrantz via
llvm-dev
>>> >> <llvm-dev at lists.llvm.org> wrote:
>>> >>> I'm building on Windows x64 using cmake, Ninja and
VS 2013 express on
>>> >>> Windows 7.
>>> >>>
>>> >>> So I have been using the LLVMSharp method on getting a
usable loadable
>>> >>> LLVM.dll[1][2].
>>
>>
>> One day, I would like to make it easier to make LLVM.dll...
We (not I) have rewritten the powershell script into a python
script[1] and where hoping that we could commit that to LLVM and have
it make a DLL during regular MSVC builds. And if possible shipping
that DLL with the Windows package (and Windows snapshot builds[2]).
>>
>>>
>>> > Further investigation show that for the MinGW build OLE32 is
added to
>>> > the dependencies for LLVMSupport.lib in the CMakeLists.txt
file, there
>>> > are a couple of other libraries added as well. This lead me to
find
>>> > that those where added for the MSVC build with a pragma(lib,
xx), so I
>>> > added such a pragma for OLE32 and that fixes my script that is
>>> > generating LLVM.dll, will also fix other peoples problems with
OLE32
>>> > missing as well.
>>>
>>> Generally speaking, static libraries like LLVMSupport are just an
>>> archive of a bunch of compiled object files, and whatever
ultimately
>>> consumes that library is responsible for providing external
>>> definitions. So, for instance, clang.exe consumes LLVMSupport.lib
and
>>> so it also links in OLE32. I believe that we usually only use
>>> #pragma(lib) to signal that non-standard libraries need to be
linked
>>> in, otherwise every source file in an archive would wind up with an
>>> unwieldy number of pragmas for all its imports, or you would have
to
>>> manually maintain that list in some common header file. I don't
think
>>> that the pragma(lib) for advapi32.lib should be there either, FWIW,
>>> but I don't know that we've ever had a hard-and-fast rule
for this
>>> sort of thing.
>>
>>
>> Sure, but the fact that static libraries can't encode their
dependencies has
>> always been an annoying missing feature, not something that we want to
>> follow if we can avoid it.
>
> Agreed.
>
>>>
>>> I'm not opposed to this patch, per se, but it feels like a
slippery
>>> slope as to what makes the cut and what does not. I would rather
see
>>> *less* non-standard pragma usage instead of more.
>>
>>
>> For these kinds of DLLs that are available on all modern versions of
>> Windows, I think it's perfectly reasonable to use the 'pragma
comment lib'
>> auto linking mechanism. Realistically, no consumer of LLVMSupport.lib
is
>> going to be surprised if it needs ole32.dll.
>
> I think we're making the same point -- no consumer of LLVMSupport.lib
> should expect to work if it doesn't use the stock set of library
> dependencies. So use #pragma(lib) for everything that's not in that
> set, but expect consumers to at least be using the stock set. Unless
> you're suggesting we stick a #pragma(lib, user32) (et al) somewhere as
> well?
So ole32 and friends are added by default by cmake[3] which is why you
are seeing them on the executables.

Looking through the source I find advapi32.lib, psapi.lib, shell32.lib
and dbghelp.lib are added via pragmas. Of these psapi.lib and
dghelp.lib are not added to the default libs by cmake[3]. So just
removing the pragmas would break the build without adding them back
into the linking libs in cmake. Tho it would break all non-cmake based
builds (that are using LLVM components) out there that don't happen to
also link those libs. That is for versions < 3.8 non-cmake builds
worked magically thanks to the pragmas.

I have no real say in what path you should take here. Pragmas for me
would be the easiest for me, since they just magically works, tho I
appreciate the technical ugliness they present. That said if you
remove the pragmas the list of libraries needed should be documented
somewhere and probably also be returned by llvm-config.exe.

If we keep the pragmas I guess we could have does link.exe add the
libs by default as a basis for which pragmas we should add in. I can't
experiment right now but user32, kernel32 and friends seems be
included by default by link.exe or they are pragmas in the MSVC
headers that the LLVM build picks.

Thanks again for your time.

Cheers, Jakob.

[1] https://github.com/VoltLang/GenLLVMDLLPy/blob/master/GenLLVMDLL.py
[2] http://llvm.org/builds/
[3]
https://cmake.org/gitweb?p=cmake.git;a=blob;f=Modules/Platform/Windows-MSVC.cmake

On Thu, Dec 24, 2015 at 1:28 AM, Jakob Bornecrantz <wallbraker at
gmail.com> wrote:
> On Wed, Dec 23, 2015 at 9:38 PM, Aaron Ballman <aaron at
aaronballman.com> wrote:
>> On Wed, Dec 23, 2015 at 3:28 PM, Reid Kleckner <rnk at
google.com> wrote:
>>> On Wed, Dec 23, 2015 at 11:25 AM, Aaron Ballman via llvm-dev
>>> <llvm-dev at lists.llvm.org> wrote:
>>>>
>>>> On Wed, Dec 23, 2015 at 1:55 PM, Jakob Bornecrantz
<wallbraker at gmail.com>
>>>> wrote:
>>>> > On Wed, Dec 23, 2015 at 5:49 PM, Aaron Ballman <aaron
at aaronballman.com>
>>>> > wrote:
>>>> >> On Wed, Dec 23, 2015 at 11:29 AM, Jakob Bornecrantz
via llvm-dev
>>>> >> <llvm-dev at lists.llvm.org> wrote:
>>>> >>> I'm building on Windows x64 using cmake, Ninja
and VS 2013 express on
>>>> >>> Windows 7.
>>>> >>>
>>>> >>> So I have been using the LLVMSharp method on
getting a usable loadable
>>>> >>> LLVM.dll[1][2].
>>>
>>>
>>> One day, I would like to make it easier to make LLVM.dll...
>
> We (not I) have rewritten the powershell script into a python
> script[1] and where hoping that we could commit that to LLVM and have
> it make a DLL during regular MSVC builds. And if possible shipping
> that DLL with the Windows package (and Windows snapshot builds[2]).
>
>>>
>>>>
>>>> > Further investigation show that for the MinGW build OLE32
is added to
>>>> > the dependencies for LLVMSupport.lib in the CMakeLists.txt
file, there
>>>> > are a couple of other libraries added as well. This lead
me to find
>>>> > that those where added for the MSVC build with a
pragma(lib, xx), so I
>>>> > added such a pragma for OLE32 and that fixes my script
that is
>>>> > generating LLVM.dll, will also fix other peoples problems
with OLE32
>>>> > missing as well.
>>>>
>>>> Generally speaking, static libraries like LLVMSupport are just
an
>>>> archive of a bunch of compiled object files, and whatever
ultimately
>>>> consumes that library is responsible for providing external
>>>> definitions. So, for instance, clang.exe consumes
LLVMSupport.lib and
>>>> so it also links in OLE32. I believe that we usually only use
>>>> #pragma(lib) to signal that non-standard libraries need to be
linked
>>>> in, otherwise every source file in an archive would wind up
with an
>>>> unwieldy number of pragmas for all its imports, or you would
have to
>>>> manually maintain that list in some common header file. I
don't think
>>>> that the pragma(lib) for advapi32.lib should be there either,
FWIW,
>>>> but I don't know that we've ever had a hard-and-fast
rule for this
>>>> sort of thing.
>>>
>>>
>>> Sure, but the fact that static libraries can't encode their
dependencies has
>>> always been an annoying missing feature, not something that we want
to
>>> follow if we can avoid it.
>>
>> Agreed.
>>
>>>>
>>>> I'm not opposed to this patch, per se, but it feels like a
slippery
>>>> slope as to what makes the cut and what does not. I would
rather see
>>>> *less* non-standard pragma usage instead of more.
>>>
>>>
>>> For these kinds of DLLs that are available on all modern versions
of
>>> Windows, I think it's perfectly reasonable to use the
'pragma comment lib'
>>> auto linking mechanism. Realistically, no consumer of
LLVMSupport.lib is
>>> going to be surprised if it needs ole32.dll.
>>
>> I think we're making the same point -- no consumer of
LLVMSupport.lib
>> should expect to work if it doesn't use the stock set of library
>> dependencies. So use #pragma(lib) for everything that's not in that
>> set, but expect consumers to at least be using the stock set. Unless
>> you're suggesting we stick a #pragma(lib, user32) (et al) somewhere
as
>> well?
>
> So ole32 and friends are added by default by cmake[3] which is why you
> are seeing them on the executables.
>
> Looking through the source I find advapi32.lib, psapi.lib, shell32.lib
> and dbghelp.lib are added via pragmas. Of these psapi.lib and
> dghelp.lib are not added to the default libs by cmake[3]. So just
> removing the pragmas would break the build without adding them back
> into the linking libs in cmake. Tho it would break all non-cmake based
> builds (that are using LLVM components) out there that don't happen to
> also link those libs. That is for versions < 3.8 non-cmake builds
> worked magically thanks to the pragmas.
>
> I have no real say in what path you should take here. Pragmas for me
> would be the easiest for me, since they just magically works, tho I
> appreciate the technical ugliness they present. That said if you
> remove the pragmas the list of libraries needed should be documented
> somewhere and probably also be returned by llvm-config.exe.
>
> If we keep the pragmas I guess we could have does link.exe add the
> libs by default as a basis for which pragmas we should add in. I can't
> experiment right now but user32, kernel32 and friends seems be
> included by default by link.exe or they are pragmas in the MSVC
> headers that the LLVM build picks.
>
> Thanks again for your time.
Ping?

Cheers, Jakob.
>
> [1] https://github.com/VoltLang/GenLLVMDLLPy/blob/master/GenLLVMDLL.py
> [2] http://llvm.org/builds/
> [3]
https://cmake.org/gitweb?p=cmake.git;a=blob;f=Modules/Platform/Windows-MSVC.cmake

r257499

On Sun, Jan 10, 2016 at 1:23 PM, Jakob Bornecrantz <wallbraker at
gmail.com>
wrote:
> On Thu, Dec 24, 2015 at 1:28 AM, Jakob Bornecrantz <wallbraker at
gmail.com>
> wrote:
> > On Wed, Dec 23, 2015 at 9:38 PM, Aaron Ballman <aaron at
aaronballman.com>
> wrote:
> >> On Wed, Dec 23, 2015 at 3:28 PM, Reid Kleckner <rnk at
google.com> wrote:
> >>> On Wed, Dec 23, 2015 at 11:25 AM, Aaron Ballman via llvm-dev
> >>> <llvm-dev at lists.llvm.org> wrote:
> >>>>
> >>>> On Wed, Dec 23, 2015 at 1:55 PM, Jakob Bornecrantz <
> wallbraker at gmail.com>
> >>>> wrote:
> >>>> > On Wed, Dec 23, 2015 at 5:49 PM, Aaron Ballman <
> aaron at aaronballman.com>
> >>>> > wrote:
> >>>> >> On Wed, Dec 23, 2015 at 11:29 AM, Jakob
Bornecrantz via llvm-dev
> >>>> >> <llvm-dev at lists.llvm.org> wrote:
> >>>> >>> I'm building on Windows x64 using cmake,
Ninja and VS 2013
> express on
> >>>> >>> Windows 7.
> >>>> >>>
> >>>> >>> So I have been using the LLVMSharp method on
getting a usable
> loadable
> >>>> >>> LLVM.dll[1][2].
> >>>
> >>>
> >>> One day, I would like to make it easier to make LLVM.dll...
> >
> > We (not I) have rewritten the powershell script into a python
> > script[1] and where hoping that we could commit that to LLVM and have
> > it make a DLL during regular MSVC builds. And if possible shipping
> > that DLL with the Windows package (and Windows snapshot builds[2]).
> >
> >>>
> >>>>
> >>>> > Further investigation show that for the MinGW build
OLE32 is added
> to
> >>>> > the dependencies for LLVMSupport.lib in the
CMakeLists.txt file,
> there
> >>>> > are a couple of other libraries added as well. This
lead me to find
> >>>> > that those where added for the MSVC build with a
pragma(lib, xx),
> so I
> >>>> > added such a pragma for OLE32 and that fixes my
script that is
> >>>> > generating LLVM.dll, will also fix other peoples
problems with OLE32
> >>>> > missing as well.
> >>>>
> >>>> Generally speaking, static libraries like LLVMSupport are
just an
> >>>> archive of a bunch of compiled object files, and whatever
ultimately
> >>>> consumes that library is responsible for providing
external
> >>>> definitions. So, for instance, clang.exe consumes
LLVMSupport.lib and
> >>>> so it also links in OLE32. I believe that we usually only
use
> >>>> #pragma(lib) to signal that non-standard libraries need to
be linked
> >>>> in, otherwise every source file in an archive would wind
up with an
> >>>> unwieldy number of pragmas for all its imports, or you
would have to
> >>>> manually maintain that list in some common header file. I
don't think
> >>>> that the pragma(lib) for advapi32.lib should be there
either, FWIW,
> >>>> but I don't know that we've ever had a
hard-and-fast rule for this
> >>>> sort of thing.
> >>>
> >>>
> >>> Sure, but the fact that static libraries can't encode
their
> dependencies has
> >>> always been an annoying missing feature, not something that we
want to
> >>> follow if we can avoid it.
> >>
> >> Agreed.
> >>
> >>>>
> >>>> I'm not opposed to this patch, per se, but it feels
like a slippery
> >>>> slope as to what makes the cut and what does not. I would
rather see
> >>>> *less* non-standard pragma usage instead of more.
> >>>
> >>>
> >>> For these kinds of DLLs that are available on all modern
versions of
> >>> Windows, I think it's perfectly reasonable to use the
'pragma comment
> lib'
> >>> auto linking mechanism. Realistically, no consumer of
LLVMSupport.lib
> is
> >>> going to be surprised if it needs ole32.dll.
> >>
> >> I think we're making the same point -- no consumer of
LLVMSupport.lib
> >> should expect to work if it doesn't use the stock set of
library
> >> dependencies. So use #pragma(lib) for everything that's not in
that
> >> set, but expect consumers to at least be using the stock set.
Unless
> >> you're suggesting we stick a #pragma(lib, user32) (et al)
somewhere as
> >> well?
> >
> > So ole32 and friends are added by default by cmake[3] which is why you
> > are seeing them on the executables.
> >
> > Looking through the source I find advapi32.lib, psapi.lib, shell32.lib
> > and dbghelp.lib are added via pragmas. Of these psapi.lib and
> > dghelp.lib are not added to the default libs by cmake[3]. So just
> > removing the pragmas would break the build without adding them back
> > into the linking libs in cmake. Tho it would break all non-cmake based
> > builds (that are using LLVM components) out there that don't
happen to
> > also link those libs. That is for versions < 3.8 non-cmake builds
> > worked magically thanks to the pragmas.
> >
> > I have no real say in what path you should take here. Pragmas for me
> > would be the easiest for me, since they just magically works, tho I
> > appreciate the technical ugliness they present. That said if you
> > remove the pragmas the list of libraries needed should be documented
> > somewhere and probably also be returned by llvm-config.exe.
> >
> > If we keep the pragmas I guess we could have does link.exe add the
> > libs by default as a basis for which pragmas we should add in. I
can't
> > experiment right now but user32, kernel32 and friends seems be
> > included by default by link.exe or they are pragmas in the MSVC
> > headers that the LLVM build picks.
> >
> > Thanks again for your time.
>
> Ping?
>
> Cheers, Jakob.
>
> >
> > [1] https://github.com/VoltLang/GenLLVMDLLPy/blob/master/GenLLVMDLL.py
> > [2] http://llvm.org/builds/
> > [3]
>
https://cmake.org/gitweb?p=cmake.git;a=blob;f=Modules/Platform/Windows-MSVC.cmake
>
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