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GCC Compiler Finally Supplanted by PCC?

Posted by ScuttleMonkey on from the all-good-things-must-end dept.

Sunnz writes "The leaner, lighter, faster, and most importantly, BSD Licensed, Compiler PCC has been imported into OpenBSD's CVS and NetBSD's pkgsrc. The compiler is based on the original Portable C Compiler by S. C. Johnson, written in the late 70's. Even though much of the compiler has been rewritten, some of the basics still remain. It is currently not bug-free, but it compiles on x86 platform, and work is being done on it to take on GCC's job."

3 of 546 comments (clear)

  1. Re:Interesting... by Anonymous Coward · · Score: 5, Insightful

    Would you like to compile Linux using a microsoft compiler? :) If it produced the best code, why not? People already compile Linux using the Intel compiler.

  2. Re:The licence is just the top of the iceberg by Anonymous+Conrad · · Score: 5, Insightful

    The whole design of GCC is perverted so that someone cannot easily extract a front-end or back-end. This is broken by design, as the GPL people do believe this would make it easier for commercial entities to `steal' a front-end or back-end and attach it to a proprietary code-generator (or language). That's entirely wrong. RMS has been worried about this, and he (through the FSF who own the copyright) have previously objected to any patches that serialize the GCC's intermediate state for just this reason. (Although GCC's new link-time optimization work will change this.)

    GCC's intermediate formats GIMPLE and GENERIC are based on a research compiler, not a deliberate perversion. There's no technical steps to stop reuse, and indeed it has been done - Sun distribute the GCC 4.0.4 front-end altered to use their own SPARC code generator as a back-end.
  3. Re:Interesting... by Anonymous Coward · · Score: 5, Insightful

    I am the GPP, incidentally, and while I'm pleased I got modded up, I certainly wasn't going for funny :). I'm sorry, but C is just a poor choice for ensuring correctness.

    First of all, open up your copy of the C standard (any of them will do) and grep for the phrase "undefined behaviour". C was standardized in a time when everyone and their dog had their own C compiler. Each C compiler did things in a different way, often in contradictory ways. The C standard came along and said "hey, you know what? You're ALL right". I'm being facetious, and the C standard has done a great job in promoting C, but the C standard has really not evolved very far in terms of guaranteeing semantics.

    I don't mean to bring this up to say that "you can't write correct code" in C or such nonsense. Obviously it's easy with good habits (I recommend comp.lang.c as the best place to pick up these habits) to write conforming and well-defined code. But, if you're trying to verify code that's already been written, either by hand or via some automated tool like a static analyzer, it is painful.

    The second problem with C is that it allows a lot of features that make verification of semantics difficult. Pointer aliasing, global variables (even "extern" global variables!!), etc. make static analysis dreadful. If you want to perform static analysis properly on C programs, it's hard to get around whole-program analysis, which is why no one uses static analysis with C code :). Seriously, what does C have beyond lint? How many people even use lint? It's not very useful.

    Of course static analysis is not the end-all be-all of ensuring correct code. There's good coding habits and testing and profiling and whatnot too. But, I would argue that whatever effort can be put into verifying C code can be better put into code in other languages. The semantics of C are sometimes loosely defined, and very often far-reaching, preventing the use of modular reasoning. Whole-program analysis is not your friend.

    What would be really cool is to see from someone like the OpenBSD crowd, if they're so keen on C, develop some verification tools that maybe only work on a very, very restricted subset of C. Any code which does not conform to this restricted "more easily verifiable" subset of C in the core OS would be rejected. I don't know how practical it would be, but it would be cool to see :). I mean as an academic, obviously I think we should all be using Z, but I understand this doesn't make good sense in a lot of real-world projects. But you want to get serious about correctness, don't pussy foot around: get serious about correctness.