[LLVMdev] [DragonEgg] Why Fortran's "call flush()" is converted to "call void bitcast (void (...)* @_gfortran_flush_i4 to void (i8*)*)(i8* null) nounwind" ?

[Anton Korobeynikov]

Dmitry,

> This is probably a question for Fortran/DragonEGG experts:
>
> Why Fortran's "call flush()" is converted to "call void bitcast (void (...)*
> @_gfortran_flush_i4 to void (i8*)*)(i8* null) nounwind" ? Why it needs
> bitcast?
Just a wild guess (basing from my llvm-gcc knwoledge though): there is
a bug with in gcc fortran frontend where it fails to create the
function TREEs with proper types. It might easily be possible that
e.g. call of function with type with no args is performed with some
amount of args, etc. It's pretty fine in gcc, but not in LLVM, the
latter is much more strict wrt this.

The only solution / workaround for this was to emit the function
definition as variadic and do bitcast at a call site (there are some
other fortran-specific stuff involved here, e.g dummy args)...

See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33097 for more info.

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University