Author: leonid
Date: 16:46:24 11/02/99
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On November 02, 1999 at 12:38:43, Heiner Marxen wrote: >I agree completely! > >Once upon a time ... well, 20 years ago I wrote a chess problem program >(precursor of CHEST) completely in assembler (IBM 370), and I did optimize >it really thoroughly. I performed my own nanoseconds timing of all the >important instructions, etc. I used even self modifying code <g>. > >When I later compared to the speed of compiled Fortran, I found a factor >of roughly 2, which I still consider to be comparatively large (i.e. my >hand optimizations were good). > >Algorithmic changes quickly saved much more than just a factor of 2, >once I changed to C, while the compiled (and optimized) code were still >rather good. For years I had the habit of manually inspecting the assembler >code generated by the C compiler, and most of the time I didn´t find >anything dramatic. Nowadays I rarely inspect the generated assembler. > >Of course, it helps to know a bit about the way the compiler produces code. > >Overall, I will never ever fall back to writing non-trivial code in assembler. >It is far too hard to maintain, a factor of 2 is not worth the hassle. >Also, portability is a great issue for me: what would I do with highly >optimized IBM/370 assembler, today? [I still have those paper listings.] > >IMO, YMMV. > >Heiner What are the main characteristics of those IBM/370? The speed and width of register. Leonid.
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