On Thu, Feb 13, 2003 at 12:07:57PM -0800, Long Li wrote:
> I am using a gcc 3.0.4 MIPS crosscompiler on Redhat. I
> found something interesting: when I use specifly -O1
> for compilation, and I can use memcpy function even I
> did not tell the compiler where I declard it or define
> it. However, when I specify -O0, then the compiler
> tells me undefined reference to this memcpy function.
> So my questions are:
> 1. Is memcpy a built-in function for gcc? But why not
> for optimization level 0?
Because using it is an optimization.
> 2. Besides memcpy, is there any other functions built
> in too?
Lots. The list varies depending on the GCC version; see the manual.
MontaVista Software Debian GNU/Linux Developer