cblas.h function declarations should include calling convention specifier

[Arech]

Hi there!
I'm trying to use OpenBLAS in my code in MSVC2015 (@ Win7 x64). The code uses __vectorcall calling convention by default, and therefore any external function declared (such as that in cblas.h) are expected to conform this calling convention (extern "C" doesn't influence on that). At the same time, OpenBLAS is built with __cdecl calling convention and therefore it can't be used until cblas.h function declarations are hacked with proper __cdecl calling convention.

For example,

void cblas_dgemm(OPENBLAS_CONST enum .....bla-bla-bla);

should be declared as:

void __cdecl cblas_dgemm(OPENBLAS_CONST enum .....bla-bla-bla);

in order to be used in code with non-cdecl calling convention.

__cdecl keyword might be Microsoft specific, but you can make generic workaround with preprocessor macros.

Could you please update function declarations of cblas.h?
Thanks!

[Arech]

I'm using cblas.h from precompiled package http://sourceforge.net/projects/openblas/files/v0.2.14/OpenBLAS-v0.2.14-Win64-int32.zip/download

[xianyi]

@Arech , Thank you for the suggestion.

[brada4]

__cdecl is default calling convention in visual studio.
#define WINAPI __cdecl
is completely redundant, and will break other code that defined it other way probably for purpose.

[Arech]

@brada4, I don't get, what's the point of your comment?

__cdecl is default calling convention in visual studio.

__cdecl is indeed the default calling convention, which means that once you switch you project away from the default (it can be done with any compiler), you will not be able to compile a code, that relies on external library that doesn't specify it's calling convention (our case).

#define WINAPI __cdecl
is completely redundant, and will break other code that defined it other way probably for purpose.

WINAPI macros is reserved by Windows SDK and mustn't be redefined unless you want hurt yourself.
OpenBLAS should probably define its own macro, like
#define OPENBLAS_CALL __cdecl
and use it in function declarations, like
void OPENBLAS_CALL cblas_dgemm(...

[brada4]

You mean netlib cblas.h should become non-portable windows-only header file?
You are free to compile openblas dll with any calling convention you imagine.

[Arech]

I mean there is no need to upset users of any compilers, who wish to use OpenBLAS from a code with a non-cdecl calling convention. Netlib just ignored existence of over9000 of other calling convention methods, but should we adopt their blindness?

The easiest workaround is to define a macro with OpenBLAS specific calling convention and prepend it to any function declaration (the age-old technique of good coding style used by all mature libraries)

The problem with __cdecl might being a Microsoft specific keyword is easily solved with some compiler determination #if's (also age-old technique of being friendly to any compiler - it's kinda dirty, but you have no other options).

[brada4]

Which means that either you compile your openblas9000 with your calling convention (which should come logical)
Or set calling convention aroound including cblas.h
Or netlib adds 9000 #ifdef-s with redundant defaults for all compilers in the world.
Which sounds most viable solution?

[Arech]

Which means that either you compile your openblas9000 with your calling convention (which should come logical)

According to this "logic" we also should recompile any external components should we want to use non-default calling convention in our app. Which is to tell the least - strange and impractical. There's absolutely no reason to do it if these external libs have correct function declarations. If they don't (like in OpenBLAS case) the only logical solution is to improve function declarations.

Or set calling convention aroound including cblas.h

Oh, really? How are you going to do that?

Or netlib adds 9000 #ifdef-s with redundant defaults for all compilers in the world.

First: friend, looks like you forgot that we're talking inside of OpenBLAS's bugtracker about OpenBLAS, not Netlib's and not about Netlib.

Second:

#ifdef _MSC_VER
#define OPENBLAS_CALL __cdecl
#else
#define OPENBLAS_CALL 
#endif

Is it really so f@$%n hard to do and the reason to f$!k up users?

Which sounds most viable solution?

I'm sorry, but sounds like you don't really understand neither the problem nor the solution. I'm not going to continue the discussion with you anymore.

[brada4]

cblas.h is nearly verbatim copy of netlib BLAS.
Do you think all 3 functions added should specify calling convention? Just to fix your override of WINAPI ?

Or you just fix your build problem yourself. Even 1st grade student knows that 32bit dll will not load in 64bit process.