questions about builtin Functions

[Altera_Forum]

hi.i need some information about builtin Functions,is there any online resources available? And where to find?thank you so much to provide me with a web page link:)

[Altera_Forum]

added:builtin function of nios 2

[Altera_Forum]

http://www.altera.com/literature/hb/nios2/n2sw_nii52010.pdf 

 Hope this helps.

[Altera_Forum]

I am also looking information about builtin functions such as __builtin_rdctl, which seems to me like a wrapper function from assembly makro rdctl to C code. Actualy I wonder if they are defined in a file, I couldn't find the definiton or any related document about it. 

 Also would it be a problem if I redefine it in my projects?

[Altera_Forum]

They are defined in the C sources for gcc, writing asm macros for them is a SMOP (and understanding the gcc asm statement rules).