[fpc-devel] Request info on static single use
vsnijders at quicknet.nl
Wed Nov 8 20:13:03 CET 2006
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) ?
>> 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
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