On Fri, 2012-06-08 at 16:54 +0800, Bin.Cheng wrote: > Hi all, > In micro-controller applications, code size is critical and the size > problem is worse if library is linked. > For example, most c programs call printf to format output data, that > means floating point code get linked even the program only want to > output non-floating point numbers. Currently, we rely on end-user to > call iprintf if the program does not want floating point. > > I noticed that GCC now can check format string of printf functions, so > I am wondering if it is possible to take advantage of this utility, by > making gcc detect whether printf prints floating point number and then > generate assembly directive in backend to pull in floating point > functions only if necessary. > > The problem is: > The check is done in front end, so how should I expose the check > result to back-end. Is there any hook utility? > > In the future, could this feature be supported by GCC in upstream? I > assuming mcu backends may have interests in this. >
Wouldn't it be much simpler and easier to just provide a customized printf implementation in the C runtime/std lib which does not use floating point types or simply prints a hex number when doing a '%f' or something like that? Another idea could be to try using a variadic template printf, if you can get the C code to compile as C++ :) Cheers, Oleg
