warnings in 1.60 when compiling with nvcc

[Alex Grund <a.grund@…>]

I'm compiling a larger project ( ​https://github.com/ComputationalRadiationPhysics/picongpu/ current dev) which uses boost heavily. However a lot of warnings are issued. Since we are quite agnostic to warnings (compiling with many warnings enabled and -Werror) this is troubling and it would be great, if those are fixed in future versions. If I remember correctly older versions (1.58) did not had them.

CUDA 7.0

boost/smart_ptr/detail/sp_counted_base_gcc_x86.hpp(49): warning: "cc" clobber ignored

boost/smart_ptr/detail/sp_counted_base_gcc_x86.hpp(65): warning: "cc" clobber ignored

boost/smart_ptr/detail/sp_counted_base_gcc_x86.hpp(91): warning: "cc" clobber ignored

boost/smart_ptr/detail/sp_counted_base_gcc_x86.hpp(75): warning: variable "tmp" was set but never used

CUDA 7.5

boost/smart_ptr/detail/sp_counted_base_gcc_x86.hpp(75): warning: variable "tmp" was set but never used

[k.ljunngkvist@…]

I can repeat that this last warning appears for CUDA 7.5 when using BOOST.

[anonymous]

This issue is still present in Boost 1.61.0

[Peter Dimov]

Can someone suggest a fix?

[anonymous]

Idea would be to list 'tmp' as an input operand not as an output operand or using something like '"r" (new)' to create an unnamed register, although I'm not that firm in inline asm. (Background: The warning arises from an inline asm block, that uses compare-and-exchange where tmp is used as a temporary in that block but listed as an output param)

[Peter Dimov]

I'd rather not touch a working inline asm block. How about something like (void)tmp; after that?

[Flamefire]

Define 'working' if it mentions a temporary as an 'output' which should be either a new temporary register or an input if that is not possible. I'd consider this a bug and instead of crafting a work-around by 'using' an unused variable I'd rather fix that bug.