Thomas Martitz <thomas.martitz@xxxxxxxxxxxxxxxxxxxxx> writes: > Am 08.02.2011 00:04, schrieb Ian Lance Taylor: >> ali hagigat<hagigatali@xxxxxxxxx> writes: >> >>> A necessary feature for GCC is to compile C/Assembly programs without >>> standard libraries for Intel architectures. >> This feature can not and will not be implemented. Some supporting >> routines are always required, particularly for gcc extensions like >> nested functions and __attribute__ ((cleanup)). > > IIRC the functions Ali mentioned (mem*) are the only required ones to > build working binaries without C library (i.e. for bare metal > targets). We do it this way at Rockbox. > > But I wonder why, the mem* functions are trivial to implement in plain > C so why does one need to provide them? I took ali to be asking to build without any libraries at all, including libgcc, which is what you get when you use -nostdlib. That can't work. I think you are talking about the case where we do use libgcc, but don't use libc. In other words: why don't we provide memcpy, etc., in libgcc, or, rather, just call libgcc-specific routines? The answer is that we expect the library provider to have a highly optimized version of those functions. That is certainly the case when using glibc on GNU/Linux. Since the library provider should already have a highly optimized version, gcc doesn't bother providing one itself. Of course we could still arrange to provide simple versions in some additional library which is only linked after libc. I would not be opposed to that. Real C programs, though, almost always call memcpy and friends themselves, and real C programs always require some level of supporting code. The current situation doesn't really bother me. Ian
