Re: When/why did function calls get cheap?

Peter Seibel wrote:
> My understanding is that in Olden Times, Real Programmers avoided
> using lots of small functions because the overhead of a function call
> was considered high. But then, somewhere along the way, the compiler
> writers got clever and made function calls cheap so now nobody worries
> about it. Is that more or less correct?


Partly. First, programmers accepted the overhead, simply because it
made code maintainable that wasn't. Then, programmers simply forgot
about the cost, taking subroutine calls for granted. [1] A few years
after that, compilers that routinely did inlining became commonplace.


[1] I did, myself. I once wondered why my Atari ST was printing so
slowly in graphics mode. I fired up the machine-level debugger and
traced through the kernel, discovering that the Atari went through
about half a dozen subroutine calls before hitting actual hardware. I
still suspected nothing, but counted CPU cycles anyway - and found
that the printer interface was waiting about 80% of the time! I then
inlined the system code, making the CPU wait 80% of the time...


Regards,
Joachim

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