Procedure Inlining

• Inlining: replace a function call by that function source code

• Advantages:

  • increase opportunities for processor optimizations
  • more opportunities for Loop Nest optimizations

• Candidates for inlining are modules that:

  • “small” i.e. not much source code
  • are called very often (typically in a loop)
  • do not take much time per call

• Inhibition to inlining:

  • mismatched in the subroutine arguments (type or shape)
  • no inlining across languages (e.g. Fortran calls C subroutine)
  • no static (SAVE) local variables
  • not varargs routines, no recursive routines
  • no functions with alternate entry points
  • no nested subroutines (like in F90)

DO I=1,N

call DO_WORK(A(I),C(I))

ENDDO

Subroutine DO_WORK(X,Y)

Y=1+X*(1+x*0.5)

END

-INLINE:list=[on|off] (default off)

-INLINE:must=sub1:never=sub2

-IPA:inline=[on|off] (default on)

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