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Re: Hashing of "switch/case" selections
- To: Zack Weinberg <zackw at stanford dot edu>
- Subject: Re: Hashing of "switch/case" selections
- From: Andy Walker <jawalker at stl dot quik dot com>
- Date: Sun, 07 Jan 2001 20:15:18 -0600
- CC: GCC general mailing list <gcc at gcc dot gnu dot org>
- References: <3A4AC4FC.35E70BEE@stl.quik.com> <20010104013910.F12948@wolery.stanford.edu>
Ok. I will.
Andy
Zack Weinberg wrote:
> On Wed, Dec 27, 2000 at 10:43:40PM -0600, Andy Walker wrote:
> [much interesting stuff]
> > My experience as a programmer is that programs are almost never written
> > with switches to more than a few hundred cases. I personally have never
> > seen one. More than that, and the programmer finds a more efficient,
> > more readable, more maintainable solution, and he can do so because he
> > has a deep knowledge of the problem that is unavailable to the
> > compiler. My seat-of-pants estimate is that 400 cases is a good, maybe
> > even high, maximum for Hash evaluations. A program containing a switch
> > statement with more than 400 cases in it probably has enough other
> > severe design problems that it will never be worth running anyway.
>
> This is true in my experience for code written by humans, but not
> necessarily for machine-generated code. Take a look at insn-attrtab.c
> in your GCC build directory, or at cp/parse.c in the source tree.
>
> zw