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Pre-Processers for Inlined C Code?

Posted by Cliff on from the taking-two-steps-instead-of-one dept.

Scott Snell asks: "I have inherited the C code for an embedded system project that has run out of code space. The source code is highly fragmented and the compiler doesnt generate efficient code for stack handling. Ideally I would direct the compiler to 'inline' a lot of the functions but unfortunately it doesnt support the inline keyword. Using macros is dangerous and manually inlining is driving me crazy! What I need is a tool that will take the source files, look for the 'inline' keyword and generate new source files that are inlined. Any ideas?"

5 of 62 comments (clear)

  1. Use macros by adb · · Score: 3, Interesting

    Unless I'm on crack, inlining all calls to a function is pretty much the same as replacing the function with a macro. The main difference between inlining and macros would be that the compiler can decide not to inline a function if it doesn't make sense (e.g., if the function is recursive and the compiler isn't up to iterative-izing it), whereas with macros you just can't do recursion safely.

  2. GCC? by dhilvert · · Score: 1, Interesting

    Is using GCC not an option?

  3. Re:Port it. by aridhol · · Score: 3, Interesting

    I believe the GNU toolchain can generate code for several embedded systems.

    --
    I can't say that I don't give a fuck. I've just run out of fuck to give.
  4. Perhaps Embedded C++ by jpkazarian · · Score: 2, Interesting

    Green Hills has proposed an Embedded C++ standard which is essentially ANSI C++ without exception handling, mutiple inheritance, namespaces, run time type identification, templates, or virtual base classes. It does support the C++ inline keyword. So the compiler will, when possible, expand functions as macros. This results in faster performance at the expense of larger code space, but smaller stack space.

    There are few problems porting code from C to C++. It's actually more difficult to port from pre- to post-ANSI C++, e.g. because of changes to the definition of the for statement. A C++ compiler is more type strict then a C compiler, meaning that more operations between different fundamental data types will be flagged as errors.

    EC++ won't result in tremendous code bloat, either. About the same order of ANSI C. Plus if this system continues to evolve, one can take advantage of easier memory allocation with new and delete as opposed to malloc and free.

    Granted the original post asked about inlining C functions. But moving to C++ gives one portability, since the inline keyword is part of the ANSI C++ standard.

  5. Complete Solution Available by Euphonious+Coward · · Score: 5, Interesting
    Assuming that Gcc doesn't target your platform (otherwise you could just switch to Gcc) you can get an excellent inlining preprocessor from Comeau Computing (look it up on Google), at a very reasonable price.

    Their preprocessor happens also to be a complete C++ compiler. You don't have to use the rest of the C++ features. (You might, for example, want to turn off exception handling.)

    Any half-assed preprocessor that just folds function bodies into line is likely to be much worse than using macros. The worst possible outcome is code that's in some weird private language that only your weird private tools understand. (Cf. Qt/KDE)