Re: High Level Language vs Assembly

"T.Shackell" wrote:
> I wanted using C alone and I knew I was using the best (known)
> algorithms. When I dropped the inner loop of the rasterizer into ASM
> and carefully hand optimized it I found I got a performance increase
> of around 120%. I think the key was I was only trying to hand-code
> less than 10 lines of C in a loop the CPU was in 95% of the time.


And interestingly, the next level of performance optimization is to go
back to high level language, that is, using "online" compilation. The
idea is that you build an assembly program while running just to solve
the problem with all the parameters at hand. For example, you have a
series of graphic figures to draw, you can make a general C routine,
an assembly routine, or you can generate a section of assembly
(actually machine) code that specifically draws the
figures. Generating it is costly, but pays off in long redundant
sequences.


Thats how high level language can be faster than assembly code.
--
Scott A. Moore is samiam@cisco.com
[This is a swell idea, and it's very well known. Mainframe sort
programs were generating machine code for the inner loop by the early
1960s, and probably did so in the 1950s. -John]

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