I think it might have been done to handle the case where i is volatile. It might also be needed for code dealing with auto decrement coupled with pointer dereferencing and the computing of pointer involves an expression having side effects.
Murthy -----Original Message----- From: Gilmore, Doug [mailto:doug.gilm...@amd.com] Sent: Wednesday, September 29, 2010 10:39 AM To: "C. Bergström"; open64-devel Subject: Re: [Open64-devel] WHIRL question I suspect that the translation is done in a way that that ensures correctness. The temp is not needed in your example, but it is needed for: j = i-- + i-- Doug > -----Original Message----- > From: "C. Bergström" [mailto:cbergst...@pathscale.com] > Sent: Wednesday, September 29, 2010 7:15 AM > To: open64-devel > Subject: [Open64-devel] WHIRL question > > (forwarding this question) > > This code > j = --i + i--; > > Is transformed into this (pseudo)WHIRL: > > STID(i) - ADD - LDID(i) ; this is the side > \ INTCONST(-1) ; effect of the --i > expression > > STID(preg_I4) - LDID(i) ; storage of the > previous > ; i value > > STID(i) - ADD - LDID(i) ; this is the side > \ INTCONST(-1) ; effect of the i-- > expression > > STID(j) - ADD - LDID(preg_I4) ; the actual > \ LDID(i) ; j = .... expression > > what is the advantage of this WHIRL instead of > > STID(i) - ADD - LDID(i) ; this is the side > \ INTCONST(-1) ; effect of the --i > expression > > STID(j) - ADD - LDID(i) ; the actual > \ LDID(i) ; j = .... expression > > STID(i) - ADD - LDID(i) ; this is the side > \ INTCONST(-1) ; effect of the --i > expression > > > the first version just uses one more WHIRL node and one more variable. > why is it used? is it because it's easier to rewrite C -> WHIRL in that > way? > > > ----------------------------------------------------------------------- > ------- > Start uncovering the many advantages of virtual appliances > and start using them to simplify application deployment and > accelerate your shift to cloud computing. > http://p.sf.net/sfu/novell-sfdev2dev > _______________________________________________ > Open64-devel mailing list > Open64-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/open64-devel ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Open64-devel mailing list Open64-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/open64-devel ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Open64-devel mailing list Open64-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/open64-devel
