Re: Switch statement code generation

"glen herrmannsfeldt" <gah@ugcs.caltech.edu> wrote in message
> Joshua Cranmer <Pidgeot18@verizon.invalid> wrote:
>> I'm trying to put together a list of various methods to do code generate
>> for switch statements.
>


<snip>


> I believe that JVM also has a special instruction for this
> operation, as the above likely don't work there.
>


I think both the JVM and MSIL/CIL have special instructions for jump
tables...




>> [I think I've seen hashing into branch tables. -John]
>
> Sounds better than branching into hash tables.
>
> -- glen
> [On machines with condition codes, I've seen binary searches expanded
> into code with compare and branch instructions; after the comparison
> you can do a three way branch on less, equal, or greater. -John]


yeah...


in my compiler (on x86 and x64) I ended up using condition codes to
implement a trinary jump of this sort.


I had intended this for implementing slightly faster switches (errm...
because my compiler does not have jump tables... lame, I know, just never
got around to it...).


from what I remember, I do a binary lookup to handle switches.




then again, I am still not using my compiler as a "general purpose" C
compiler, and so there are still a few deficiencies I have never really
gotten around to fixing.


so many other things to work on, such as the x86 interpreter (now works ok,
and is ~170x slower than native, but still lacks a good deal in terms of API
bindings, me left thinking I may need some sort of IDL-like technology for
this, ...), ...


maybe just a whole lot of busywork, I don't know...

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