On Mon, 2006-12-11 at 22:53 -0500, Robert Baruch wrote: > Hi Scott, > > Well, I'm interested mainly in the 12-bit PIC architecture. I know > that T. Scott Dattalo has worked on the 14- and 16-bit architectures, > however I'm not sure he's still actively developing. Also, he's added > further complication by adding pCode on top of iCode, so it's not > like it would be any easier to understand :/
I'm still around, but I don't develop for SDCC anymore. In hindsight, adding pCode to SDCC was a mistake. It should have been added to the linker (and if I can *ever* get ahead on the simulator I'd like to port pCode to gplink or even a stand alone optimizer). But at the time I started gplink was just being developed and PIC relocatable code was little used. Things have changed. However, the pCode design still retains an abstraction that enables subsequent optimization in the context of machine code. It's somewhat analogous to gcc's RTL in this regard although totally different. BTW, Ralph has put more work than I have into the PIC port. He's fixed major bugs, gotten the relocatable code generation work and has maintained the code for the last 4 years. > What gets me is that looking at the different back ends, they all > seem to have a main, a register allocation, and a generator. Many > pieces of each back end look almost the same, but with some > differences that are hard for me to make sense out of, since I'm not > even sure what the common portions are supposed to do. All compilers that support multiple architectures are similarly designed (at least the few I've seen). At the machine generation stage, there really is no other practical choice. > I have some vague ideas about some pieces, such as the asmop set of > functions which generate assembly code for operands, but I'm not even > sure how that relates to the register allocation, or how the whole > contraption determines what symbols are spillable, rematerializable, > and so on. I didn't see a question in your message, but I think you're asking how to add 12-bit support to SDCC. Someone privately just asked what it would take to do this and I said 6 man months. Fortunately, the 12-bit port has the luxury of building off of the 14-bit port. Who knows, maybe the pCode generation can accommodate both! Scott ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Sdcc-user mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/sdcc-user
