[fpc-devel] Request info on static single use

[Vincent Snijders]

Jonas Maebe schreef:
> 
> On 8 nov 2006, at 17:46, Micha Nelissen wrote:
> 
>>
>> Is SSU easier to implement than SSA ?
> 
> No, it's a bit more work.
> 
>> Aren't variables often more used than assigned (so more generated 
>> variables by SSU) ?
> 
> Yes.
> 
>> How do the achieved optimizations compare ?
> 
> SSU gives somewhat better results on register-starved architectures. The 
> change from SSA to SSU didn't make any difference for PPC for the 
> compiler+rtl (it can give a difference for large procedures with a lot 
> of variables which are used in different "phases" of course). It saves 
> about 5kb on the compiler on Linux/i386 compared to SSA-only.
> 
>

Will you be working on SSA and/or SSU with control blocks (e.g. using 
SSA in procedures where a for loop is used) before 2.2? Or will that be 
released only in a later version.

A synthetic example that will benefit is the CalculatePoint procedure of 
http://svn.freepascal.org/svn/fpc/trunk/tests/bench/shootout/src/mandelbrot.pp

Vincent