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From: haitex@pnet01.cts.com (Wade Bickel)
Newsgroups: comp.sys.amiga
Subject: Re: M2Amiga, a new Modula-2 compiler
Message-ID: <2010@crash.CTS.COM>
Date: Mon, 16-Nov-87 21:36:14 EST
Article-I.D.: crash.2010
Posted: Mon Nov 16 21:36:14 1987
Date-Received: Thu, 19-Nov-87 19:53:58 EST
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dillon@CORY.BERKELEY.EDU (Matt Dillon) writes:
>:The code for a ROM call is exactly the same as the code for a procedure call
>:to a prodecure of an other module. The placing of parameters into registers
>:doesn't make a big difference. With other compilers you have an external call
>:to the assembler stub popping parameters into registers and eventually pushing
>:results back on the stack again and the basic ROM call.
>:
>:Simplified: The time others arrive in their stubs we arrive at the function in
>:ROM. 
>:
>:A German jounalist doing some reseach on this came up with following figures.
>:machine cycles for a Library Call.
>:TDI ~250, Manx ~140, M2Amiga 94, he complained because the optimal Assembler
>:call only uses 74 cycles. This still leaves some space for improvement :-) 
>
>	Well, I wouldn't get too caught up in it.  For one thing, those 
>numbers are obviously averages over quite a few different calls, because 
>things like Remove() from assembly take maybe 22 cycles of overhead
>(loadregister-4, jsr-18) in the call... common RTS and meat not included.
>If you look carefully, I think you will find that the library calls that run
>quickest take fewer arguments and thus less overhead, and the library calls 
>that take more arguments generally take longer to complete anyway, so the 
>overhead can almost be thought of as a straight percentage of the execution
>time for the call.
>
>	This straight percentage is going to be very low, so optimizing
>from 140 to 74 isn't going to be noticeable at all.
>
>				-Matt
>	


        Seems to me any cycles are important.  Perhaps not for general
    code, but when it comes to the decision as to weather or not to use
    assembly, this could make a difference.

                                                Wade.

        PS: Matt, have you tried Modula-2?  I know your a C programmer, 
                and just wondered if you'd given M2 a look.


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