This topic only applies to Intel® Many Integrated Core Architecture (Intel® MIC Architecture).
You can write functions that you intend to run on a target, and sections of offloaded code, to take advantage of target-specific functions.
When the compiler generates code for the coprocessor, it defines the macro __MIC__. You can write target-specific code within a !DIR$ if defined __MIC__ section.
Note
Do not use the __MIC__ macro inside the statement following a !DIR$ OMP OFFLOAD statement. You can, however, use this macro in a subprogram called from the directive.
Example
The implementation of the class F32vec is specialized for the CPU and the coprocessor. The offloaded code can use the specialized version if it runs on the coprocessor. If the offload fails and the construct runs on the CPU, it uses the CPU version.
!DIR$ ATTRIBUTES OFFLOAD : mic :: foo
integer function foo()
implicit none
!DIR$ if defined (__MIC__)
foo = 1 ! Code is running on coprocessor
!DIR$ else
foo = 0 ! Code is running on host
!DIR$ endif
end function foo
program main
implicit none
! Local variables
integer :: result
integer :: foo
!DIR$ ATTRIBUTES OFFLOAD : mic :: foo
! Call foo on host
result = foo()
! Print results
if ( result ) then
write (*,*) "Code ran on coprocessor"
else
write (*,*) "Code ran on host"
end if
! Call foo on MIC
!DIR$ OFFLOAD TARGET(mic)
result = foo()
! Print results
if ( result ) then
write (*,*) "Code ran on coprocessor"
else
write (*,*) "Code ran on host"
end if
end program main
