On Samstag 24 Oktober 2009, Ullrich von Bassewitz wrote: > On Sat, Oct 24, 2009 at 07:59:13PM +0200, Groepaz wrote: > > mmmmh, is that optimizer purely rule based? > > I'm not sure what you mean with that. It's code, so there are definitely > rules. But this is probably not what you're talking about. > > The code generator stores the code in an abstract form. Several other parts > supply more information. As an example, for each instruction (even > subroutine calls if possible), information about register usage is > collected. The backend knows which registers are used and which ones are > destroyed. On request (for steps that need it), information about register > and zero page contents is generated. As posted a few days ago, this takes > also branches into account. If the contents of a register have the same > value in all execution paths leading to some line of code, the backend > knows the value at this point. And so on ... ah yes ok. by "rule based" i ment the classic peephole optimizer approach by matching patterns of code (usually textbased) without further analysis of register values, flags etc. -- http://www.hitmen-console.org http://magicdisk.untergrund.net http://www.pokefinder.org http://ftp.pokefinder.org Es ist nie ganz richtig irgend etwas für ganz falsch zu halten. <Heinz Pol> ---------------------------------------------------------------------- To unsubscribe from the list send mail to majordomo@musoftware.de with the string "unsubscribe cc65" in the body(!) of the mail.Received on Sat Oct 24 20:28:40 2009
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