Cheng Renquan schrieb: > From: Andrew Haley <aph@xxxxxxxxxx> >> It's an interesting point. Do you think that the gccint manual should >> assume some knowledge of how optimizing compilers work? >> It's explained in >> Advanced Compiler Design and Implementation, Steven Muchnick, ISBN 1558603204 >> and >> http://en.wikipedia.org/wiki/Static_single_assignment_form >> We have never to my knowledge included links to Wikipedia in gcc >> documentation, but this might be a good time to start. >> >> Andrew. > > Thank you, I've also found SSA 's meaning through its abbrev wikipedia entry, > > http://en.wikipedia.org/wiki/SSA > > but for PHI, I still did't find a good entry, > > http://en.wikipedia.org/wiki/PHI > > Someone know what PHI means, please tell, thank you. My native language > is not English, sorry for my understanding, but if someone really know > "PHI", please tell, I will thank you; > > All through gccint manual, I only find one paragraph, looks like a > definition for "PHI function" or "PHI node", but it also doesn't explain > what "PHI" abbrev for? is "PHI" part of some word, or initial letter of > three words? PHI is Phi-Function where Phi stands for uppercase greek Phi, i.e. Φ in HTML or \Phi in TeX. It's a concept rather that an abbrev. Suppose you have C code like if (a) x = 1; else x = 2; In SSA form each variable must not be set more than once (statically). So new names are introduced for x like x_1 and x_2 if (a) x_1 = 1; else x_2 = 2; These two values have to be "merged" again to get x. The magic which does (or expresses) this is denoted as PHI and called "Phi-Function": if (a) x_1 = 1; else x_2 = 2; x = PHI (x_1, x_2) > I mean: if gccint has a terminology index or table, at least explain > what it abbreviated for, maybe that would look better; > just like any technology book has a term glossary, at the end; Yes, a glossary would be great. Georg
