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Date: Mon, 04 Aug 2008 12:48:26 +0300
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Subject: Re: [sqlite-dev] VM optimization inside sqlite3VdbeExec
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Marco Bambini wrote:
> Inside sqlite3VdbeExec there is a very big switch statement.
> In order to increase performance with few modifications to the  
> original code, why not use this technique ?
> http://docs.freebsd.org/info/gcc/gcc.info.Labels_as_Values.html
>
> With a properly defined "instructions" array, instead of the switch  
> statement you can use something like:
> goto * instructions[pOp->opcode];
> ---
> Marco Bambini
> http://www.sqlabs.net
> http://www.sqlabs.net/blog/
> http://www.sqlabs.net/realsqlserver/
>
>
>
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> sqlite-dev mailing list
> sqlite-dev@sqlite.org
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>   
All the world's not a VAX.  This technique is GCC-specific. The SQLite 
source must be as portable as possible thus tying it to a specific 
compiler is out of the question. While one could conceivably use some 
preprocessor magic to provide alternate implementations, that would be 
impractical considering the sheer size of the code affected.
On the other hand - perhaps you could benchmark the change and provide 
some data on whether this actually improves performance?


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